JP4714658B2 - Steel heating method - Google Patents

Description

  The present invention relates to a method for heating a steel material.

  For example, in a hot rolling process for steel sheets, a cast slab is heated in a heating furnace and then roughly rolled in a roughing mill. A rough bar formed by rough rolling is finish-rolled in a finishing mill, and a steel plate having a target thickness is wound on a winder. These processes are performed in a series of hot rolling lines, and in this hot rolling line, a large number of slabs are continuously conveyed and processed one by one.

  By the way, the rough bar immediately after the rough rolling has a non-uniform temperature distribution, and if finish rolling is performed as it is, the material properties such as mechanical properties vary. In general, for example, in the width direction of the coarse bar (the direction substantially perpendicular to the length direction (movement direction)), the temperature becomes the highest on the edge side (side part) than the central part of the coarse bar. The edge of the coarse bar has the most heat, so it is the coldest. In addition, the temperature distribution in the width direction of the coarse bar is often asymmetric (not symmetrical with respect to the center in the width direction).

  In order to make the temperature distribution in the width direction of such a coarse bar uniform, a configuration having a plurality of heaters for partially heating the coarse bar has been conventionally proposed (see Patent Document 1). That is, in Patent Document 1, a heating pattern (heating profile) by the heater in the width direction of the coarse bar is stored in a computer in advance for each width of the coarse bar, each heater movement amount (shift amount), and each temperature increase amount. In addition, a thermometer is placed upstream of the heater in the direction of movement of the coarse bar, and the temperature distribution in the width direction of the coarse bar before heating the coarse bar with the heater is ascertained from the thermometer measurement results. A configuration is shown in which a difference from the target temperature distribution in the width direction of the rough bar is obtained, and the moving amount of the heater and the temperature increase amount are selected by a computer so that the difference is heated. In addition, the computer commands the sequencer (generally called PLC (Programmable Logic Controller)) of the heater movement amount and the temperature increase amount selected by the computer to instruct the heater movement amount and the temperature increase amount. A configuration for adjusting the amount is shown.

JP 2004-195497 A

  The first problem of the present invention is that even if the temperature distribution in the width direction of the coarse bar is asymmetrical, the temperature of the coarse bar is made uniform by appropriately controlling the temperature in the width direction and the length direction. That is. That is, in the conventional heating method, when the temperature distribution in the width direction of the coarse bar is asymmetrical, it is difficult to control the temperature distribution in the length direction. For example, Patent Document 1 describes a method of making a temperature distribution uniform when the temperature distribution in the width direction of the coarse bar is symmetric, but it is made uniform when the temperature distribution is asymmetrical. It does not explain how to do this.

  By the way, for example, when the method of Patent Document 1 is applied to control a temperature distribution that is asymmetric in the width direction, a matrix that includes data for each temperature increase amount of each heater for controlling the temperature distribution that is asymmetrical to the left and right. It is necessary to search and extract appropriate values from the matrix so that the movement amount and heating amount of each heater are individually adjusted. However, if such heating control is actually performed, the storage area and the number of steps for retrieval extraction become enormous and cannot be processed in the PLC. If an attempt is made to link a computer and a PLC, problems such as a long calculation time of the computer, a large variation in the calculation time, and a long data transfer time between the computer and the PLC occur, and it is difficult to appropriately perform sequence control at a constant cycle.

  That is, generally, in sequence control, the control cycle is 10 ms to 100 ms, and the calculation step in the PLC is about 20K steps. It is necessary to keep this control cycle constant, and for this purpose, it is preferable that there is little variation in the transfer cycle for transferring data from the computer to the PLC. When the time is long or the variation in calculation time is large, there is a problem that the transfer cycle becomes long or the variation occurs. In order to keep the control cycle constant, it is preferable to perform the calculation only in the PLC, rather than performing the calculation in the computer and transferring the data to the PLC, but the storage area for storing the heating profile, matrix, etc. Therefore, it is difficult to store and calculate the heating profile, matrix, etc. using only the PLC. In particular, when the temperature distribution in the width direction of the coarse bar is asymmetrical, the information contained in the matrix, that is, the required storage area is further increased. It was difficult. Therefore, it is necessary to install a computer separately from the PLC. However, as such a computer, a high-performance computer with a high calculation speed and data transfer speed must be used, and there is a concern that the equipment cost increases. .

  In general, for example, a relational expression (empirical expression) that expresses the relationship between the amount of movement of the heater, the output, the amount of temperature rise, etc. is created in advance, and calculation is performed using this relational expression. A method of deriving the amount of movement of the heater, the output, etc., that can obtain a temperature increase amount of 10% is also conceivable. However, such a relational expression generally has to be solved by using an implicit method (a method for obtaining a solution by repeatedly performing calculation until convergence to a certain value), and the calculation speed varies. Is likely to occur. In addition, it takes a transfer time to calculate by a computer separately from the PLC and send the result to the PLC, and this method is also unsuitable for sequence control.

  Furthermore, when controlling a plurality of transverse heaters side by side as in the premise of the present invention, there is a phenomenon in which the state of the heating area (distribution of induced current, etc.) changes as the output of each heater changes. As a result, interference of the induction current between the heaters occurs, and the accuracy of temperature distribution control decreases.

  In order to reduce the influence of the heating area of each heater on each other, it seems that the distance between the heaters (distance between the cores) in the length direction of the coarse bar should be sufficiently wide. In this case, since the temperature of the portion heated by the upstream heater moves to the downstream heater side, the temperature of the portion is greatly reduced, so that the heating efficiency is reduced and the accuracy of temperature distribution control is reduced. Problems arise. That is, the distance that can be provided between the heaters in the length direction of the coarse bar is limited, and it is not desirable to make the distance larger than a certain distance (for example, about 3 m). Therefore, it is difficult to adjust the distance to reduce the influence of the heating regions on each other.

  That is, the present invention has been made in view of the above points, and an object thereof is to provide a heating method capable of controlling both the temperature distribution in the width direction and the temperature distribution in the moving direction of a steel material such as a rough bar. . In particular, when the temperature distribution in the width direction is asymmetrical, when performing sequence control, or when using a transverse induction heating device as a heater, etc., heating that can suitably control the temperature distribution of the steel material It aims to provide a method.

  When performing temperature control in the length direction of a steel material (rough bar, etc.), the inventors set the heater output to be the same for a location (predetermined position) in the same length direction, and the heater in the width direction. It was found that by adjusting the position of each, it becomes possible to control at a constant cycle even in a temperature distribution that is asymmetric in the width direction, and the temperature controllability in the width direction and length direction of the steel material becomes extremely high. In view of this, the following steel material heating method was invented.

That is, in order to solve the above-described problem, according to the present invention, a method of heating a steel material by a plurality of heaters before finish rolling in a hot rolling process, while moving the steel material along the length direction, The steel material is heat-treated in this order by a first heater, a second heater, and a third heater, and the first heater, the second heater, and the third heater are transverse induction heating devices. And any one of said 1st heater, 2nd heater, and 3rd heater is a heater for center parts arrange | positioned so that a core may face the center part in the width direction of the said steel materials, Either one is a first side heater arranged so that the core faces one edge in the width direction of the steel material, and either one is a core in the width direction of the steel material. Arranged to face the other edge A second side heater, a first interval formed between the core of the first side heater and the central portion of the steel material; and the core of the second side heater And the second gap formed between the steel material and the central part of the steel material can be changed, respectively, and is given to the central part of the steel material by the heat treatment over the length direction of the steel material. target value of NoboriAtsushiryou [Delta] T _C being, with the temperature Yutakaryou [Delta] T _C and heating amount given by the heat treatment on the first lateral portion positioned between the central portion and one edge of the steel the target value of the Atsushi Nobori amount difference Delta] E _R, and a central portion and a second said the Atsushi Nobori amount given by the heat treatment on the side portion temperature Yutakaryou located between the other edge of the steel based on the target value of the temperature rise amount difference Delta] E _L and [Delta] T _C, the target value of the output of the central unit heater, said first The target value of the output of the side heater, the target value of the output of the second side heater, the target value of the first interval, and the target value of the second interval are obtained, and the length of the steel material Output of the central heater when the core of the central heater faces a predetermined position in the direction, the first when the core of the first side heater faces the predetermined position While the output of the side heater is the same as the output of the second side heater when the core of the second side heater faces the predetermined position, the first interval, and A method for heating a steel material is provided, wherein the second interval is adjusted.

In the heating method of the steel, the the temperature Yutakaryou [Delta] T _C, the same output from each other, and the first distance, the first relational expression indicating a relationship between the second interval using The target value of the same output, the target value of the first interval, and the target value of the second interval may be obtained. Wherein the first relationship is the temperature Yutakaryou [Delta] T _C, the temperature increase amount given to the central portion of the steel material in the predetermined position by the central heater, said first side heater The amount of temperature increase given to the central portion of the steel material at the predetermined position by the second side heater and the amount of temperature increase given to the central portion of the steel material at the predetermined position by the second side heater It may be expressed by a linearly coupled expression. The amount of temperature increase given to the central portion of the steel material at the predetermined position by the first side heater may be expressed using a second-order polynomial with the first interval as a variable. The amount of temperature rise given to the central portion of the steel material at the predetermined position by the second side heater may be expressed using a second-order polynomial with the second interval as a variable.

Further, the same output is obtained by using a second relational expression representing the relationship between the temperature increase difference ΔE _R , the same output, the first interval, and the second interval. Target value of the first interval, target value of the first interval, and target value of the second interval may be obtained. In the second relational expression, the temperature rise difference ΔE _R is calculated based on the temperature rise amount given to the first side portion at the predetermined position by the heating by the center heater and the center portion. By the heating amount difference from the heating amount given to the central portion of the steel material at the predetermined position by the heating by the heater, and by the heating of the first side heater and the second side heater The center of the steel material at the predetermined position by the heating amount given to the first side portion at the predetermined position and the heating of the first side heater and the second side heater. The difference in temperature rise from the temperature rise given to the part may be expressed by a linearly coupled expression. A heating amount applied to the first side portion at the predetermined position by heating of the first side heater and the second side heater, the first side heater, and The difference in temperature rise from the temperature rise given to the central portion of the steel material at the predetermined position by the heating of the second side heater is a variable between the first interval and the second interval. May be expressed using a first-order polynomial.

Moreover, the the heating amount difference Delta] E _L, the same output from each other, with said first distance, a third relational expression indicating a relationship between the second gap, the mutually identical output The target value for the first interval, the target value for the first interval, and the target value for the second interval may be obtained. The third relational expression, the Atsushi Nobori amount difference Delta] E _L, said second side for the central portion and the Atsushi Nobori amount given to portions in the predetermined position by heating by the heater for the center portion By the heating amount difference from the heating amount given to the central portion of the steel material at the predetermined position by the heating by the heater, and by the heating of the first side heater and the second side heater The center of the steel material at the predetermined position by the heating amount given to the second side portion at the predetermined position and the heating of the first side heater and the second side heater. The difference in temperature rise from the temperature rise given to the part may be expressed by a linearly coupled expression. A heating amount given to the second side portion at the predetermined position by heating of the first side heater and the second side heater, the first side heater, The difference in temperature rise from the temperature rise given to the central portion of the steel material at the predetermined position by the heating of the second side heater is a variable between the first interval and the second interval. May be expressed using a first-order polynomial.

A target value of the output of the central heater, a target value of the output of the first side heater, a target value of the output of the second side heater, a target value of the first interval, and The target value of the second interval is
ΔT _C = (K1 + γ · K3 · _XL ² + γ · K3 · X _R ² + γ · K4) · α
ΔE _R = (K2 + γ · K51 · X _R + γ · K52 · X _L + γ · K6) · α
ΔE _L = (K2 + γ · K51 · X _L + γ · K52 · X _R + γ · K6) · α
(K1, K2, K3, K4, K51, K52, K6: coefficient depending on the width of the steel material, γ: the state of the heating region by the first heater, the state of the heating region by the second heater, and the first A coefficient related to the state of the heating area by the three heaters, X _R : the first interval, X _L : the second interval, α: the output of the central heater with respect to the maximum output of the central heater The ratio of the output of the first side heater to the maximum output of the first side heater, and the second side heater to the maximum output of the second side heater. It may be obtained using the output ratio).

  The target value for the first interval and the target value for the second interval may be the same. Further, a target value of the output of the central heater, a target value of the output of the first side heater, a target value of the output of the second side heater, a target value of the first interval, The target value of the second interval may be calculated by an explicit method. The central heater, the first side heater, and the second side heater may be controlled at a constant cycle.

Before performing the heat treatment, the temperature T _C of the central part of the steel material, the temperature T _{RE of} the first side part, the temperature T _LE of the second side part are detected, the temperature T _C , and , A target value of the temperature rise ΔT _C is obtained from the target temperature T _t by the heat treatment, a target value of the temperature rise difference ΔE _R is obtained from the temperatures T _C , T _RE , and the temperatures T _C , T A target value of the temperature increase amount difference ΔE _L may be obtained from _LE .

According to the present invention, for example, even when the temperature of the steel material changes in the width direction and the length direction (when the temperature distribution varies in both the width direction and the length direction of the steel material) target value of [Delta] T _C, the target value of the temperature rise amount difference Delta] E _L, based on the target value of the temperature rise amount difference Delta] E _R, the output of the heater for the center portion, the output of the first side heater, a second side The temperature distribution in the width direction of the steel material can be suitably controlled by adjusting the output of the heater, the first interval, and the second interval. Even if the steel material has an asymmetric temperature distribution in the width direction by adjusting the target value of the output of each heater (target value of the output ratio) for the predetermined position in the length direction of the steel material, it is constant. Each target value can be calculated in the calculation time. Thereby, the sequence control can be performed at a constant cycle.

Hereinafter, preferred embodiments of the present invention will be described. First, when examining the present embodiment, the inventors examined the rough bar H as a steel material (see FIG. 1) before heating (after rough rolling in a roughing mill 11 described later) and then in the soaking section 13. The temperature distribution in the length direction (before soaking) was analyzed, and it was confirmed that it had a temperature distribution as shown in FIGS. In addition, the inventors have found that there is the following relationship with respect to the temperature rise required to control the temperature distribution to obtain a uniform temperature distribution in the width direction. That is, should the temperature rise margin of the center portion _{P C} of the crude bar H (central portion in the width direction D2) and (described later NoboriAtsushiryou [Delta] T _C), a crude bar H described later side portions _P R _{(P L)} between the central portion P difference required temperature increase margin due to the temperature difference _C (temperature increase amount difference below ΔE R _{(ΔE L)),} it has been found that there is a rough linear relationship. Further, the output of the central heater (for example, the second heater 32 described later) and the output of the side heater (for example, the first heater 31 and the third heater 33 described later) are set to the length of the coarse bar H. It was found that it is suitable to make the same output for the same position in the vertical direction.

First, the temperature distribution of the coarse bar will be described. Temperature distribution of the coarse bar H after being rough rolling in a rough rolling mill 11, for example, as shown in solid lines in FIG. 2, gradually becomes hot as it goes from the center P _C on the left and right edges side, side portions P _R, has become (maximum temperature at the highest temperature, the left half of the crude bar H in the right half of the crude bar H) locally hottest near P _L, right and left edges often heat dissipation So it is the coldest. Here, the side portions P _R, outside the central portion P _C of the crude bars H (right edge side), a portion positioned inside the right edge of the rough bar H, for example, have a width of 1200mm in crude bar H, it is along the length portion of the crude bar H at about 150mm about inside the right edge (portion along the longitudinal direction at about 450mm about the outside from the central portion P _C). Side portions P _L is outside the central portion P _C of the crude bars H (left edge side), a portion positioned inside the left edge of the rough bar H, for example, crude bar H having a width of 1200mm in a along the length portion of the crude bar H at about 150mm about inside the left edge (the portion along the length in approximately 450mm about the outside from the central portion P _C).

  Note that the temperature distribution in the width direction D2 of the coarse bar H is left-right asymmetric (temperature distribution forming a substantially asymmetrical M-shaped curve on the graph with the horizontal axis being the position in the width direction and the vertical axis being the temperature). There are many cases. For example, if the temperature difference between the maximum temperature in the right half of the coarse bar H and the maximum temperature in the left half is 2 ° C. or more, it is defined as a bilaterally asymmetric temperature distribution. It can be said that it has an asymmetric temperature distribution over the entire length. In the illustrated example, the highest temperature in the width direction D2 of the coarse bar H is the highest temperature in the right half of the coarse bar H, and is higher than the highest temperature in the left half of the coarse bar H.

That is, in the illustrated example, the temperature _{T C} of the center portion _{P C} of the crude bar H, the temperature _{T RE} lateral portion _{P R,} relationship between the temperature _{T LE} of the side portion _{P L is, T C <T} LE _{<T It is RE} . In other words, the target value [Delta] T _Ct of NoboriAtsushiryou [Delta] T _C to be given by the soaking treatment to the central portion _{P C} of the crude bars _{H (= T t -T C,} T t: target temperature after soaking) target value [Delta] T _REt of NoboriAtsushiryou [Delta] T _RE should be given by the soaking treatment against lateral portion _{P R} of crude bars _{H (= T t -T RE)} , Hitoshi against side portions _{P L} of crude bar H The relationship between the target value ΔT _LEt (= T _t −T _LE ) of the _temperature increase ΔT _LE to be given by the heat treatment is ΔT _REt <ΔT _LEt <ΔT _Ct .

Further, as indicated by a solid line in FIG. 3, the temperature distribution in the length direction of the rough bar H after rough rolling in the roughing mill 11 is such that the temperature is between the front end portion and the rear end portion. It is in the state where the part which becomes low temperature and the part which becomes high temperature exist alternately. That is, the temperature T _C of the center portion P _C is often up and down alternating in the longitudinal direction. Similarly, the temperature _{T RE} lateral portion _{P R,} even if the temperature _{T LE} of the side portions _{P L,} often up and down alternating in the longitudinal direction.

The inventor also shows how the temperature distribution in the width direction of the rough bar H after rough rolling in the rough rolling mill 11 changes in the length direction (how it is different at different positions in the length direction). Was analyzed). As a result, when the temperature _{T C} of the center portion Pc is low, the lateral portions _P R, the temperature _T RE of _{P L, T LE} was also found that there is less tendency respectively. _Further , it has been found that the target values ΔT _REt and ΔT _LEt described above are substantially proportional to the target value ΔT _Ct . In other words, the difference between the target value [Delta] T _Ct and the target value [Delta] T _REt, i.e., the target value Delta] E _Rt of heated amount difference _{ΔE R (= ΔT Ct -ΔT REt} = (T t -T C) - (T t - _{T RE) = T RE -T C} ) also be substantially proportional to the target value [Delta] T _Ct, and the difference between the target value [Delta] T _Ct and the target value [Delta] T _LET, i.e., the target value Delta] E _Lt of heated amount difference Delta] E _{L (= ΔT Ct -ΔT LEt = (} T t -T C) - (T t -T LE) = T LE -T C) was also found that almost proportional to the target value [Delta] T _Ct (see FIG. 4).

Note that, from FIG. 4, a linear gradient (proportional constant k _R ) approximating the relationship between the temperature rise (target value) ΔT _Ct and the temperature rise difference (target value) ΔE _Rt and the temperature rise (target value) ΔT _It can be seen that the slope of the straight line (proportional constant k _L ) approximating the relationship between _Ct and the temperature rise difference (target value) ΔE _Lt is different from each other. There are also variations in actual measured values with respect to the approximate straight line.

  Incidentally, the tendency of the temperature distribution as shown in FIG. 2, FIG. 3, and FIG. 4 is as follows. Heating in the heating furnace 10 described later, rough rolling by the roughing mill 11, heat removal on the transport roll 18, etc. Is thought to have influenced.

On the basis of the characteristics of the temperature distribution as described above, the inventors during soaking, when increasing the NoboriAtsushiryou [Delta] T _C of the central portion P _C is KakuNoboru Yutakaryou difference Delta] E _R, Delta] E _L even temperature respectively by controlling so as to increase in proportion to the temperature amount [Delta] T _C, the central portion P _C and the side portions P _R also in the length direction of the rough bar _H, variations in the temperature of the P _L is small (the temperature T _C, It was found that a temperature distribution (with high uniformity of T _RE and T _LE ) can be obtained. Further, in order to finely control the temperature distribution, such as adjustment corresponding to the difference between the proportional constants k _R and k _L , the central heater 32 is fixed, and the left and right heaters 31 and 33 are individually arranged in the width direction. It has been found that it is necessary to adjust the distance X _R and X _L (which will be described later) by adjusting the position to the position, and the present embodiment has been completed.

  Next, the equipment configuration used in the present invention will be described below. FIG. 5 is a schematic diagram showing an outline of the configuration of the hot rolling facility 1 in which hot rolling is performed. The hot rolling equipment 1 includes, for example, a heating furnace 10, a rough rolling mill 11, a cutting machine 12, a soaking section 13, an edge heater 15, a finishing rolling mill group 16 and a winding machine that realize the heating method according to the present embodiment. A hot rolling line L provided with machines 17 and the like arranged in this order in the horizontal direction is configured. Moreover, the conveyance roll 18 which conveys the steel material H along the moving direction D1 (passing plate direction, the length direction of the steel material H) of the horizontal direction toward the winder 17 from the heating furnace 10 is provided. In the present embodiment, the steel material H that is a rolled material is referred to as a slab H, a rough bar H, and a steel plate H according to the rolling stage. Further, the hot rolling facility 1 includes a first temperature detector 21 that detects the temperature of the coarse bar H before adjusting the temperature distribution of the coarse bar H in the soaking section 13, a second temperature detector 22, A third temperature detector 23 and a speedometer 24 for detecting the transport speed of the transport roll 18 are provided. Moreover, the control apparatus 25 which controls the soaking | uniform-heating part 13 based on the temperature detection value by the temperature detectors 21,22,23 is provided.

  The heating furnace 10 is, for example, a walking beam type continuous heating furnace, and can reheat the cast slab H to a temperature necessary for rolling. The rough rolling mill 11 forms the rough bar H by rolling the slab H to a thickness suitable for finish rolling. The coarse bar H is transported on the transport roll 18. The soaking part 13 can control the temperature distribution of the coarse bar H. The configuration of the soaking part 13 will be described in detail later. The edge heater 15 heats the left and right edges in the width direction of the coarse bar H. The finish rolling mill group 16 is composed of a plurality of finish rolling mills arranged along the hot rolling line L, and the steel bar H can be formed by rolling the coarse bar H to a target final product thickness. The winder 17 is configured to wind up the finish-rolled steel sheet H in a coil shape.

  Next, the configuration of the soaking part 13 will be described in detail. The soaking unit 13 includes a first heater 31 as a first side heater, a second heater 32 as a center heater, and a third heater 33 as a second side heater. The rough bar H is partially heated by the heaters 31, 32, and 33, whereby a predetermined heat treatment, that is, a soaking process can be performed on the rough bar H.

  Each of the heaters 31, 32, and 33 is a heater made of, for example, a transverse induction heating device, and has substantially the same configuration, and is substantially the same heater. As shown in FIG. 6, the heater 31 (32, 33) includes a core (upper iron core) 41 disposed above the transport roll 18 and a core (lower iron core) 42 disposed below the transport roll 18. I have. Although not shown, the heaters 31 and 33 are provided with a heater moving mechanism for integrally moving the core 41 and the core 42 relative to the transport roll 18. In the present embodiment, since the heater 32 is not moved with respect to the transport roll 18, the heater 32 need not be provided with a heater moving mechanism.

  The core 41 has, for example, a substantially U-shape, and is arranged so that both end portions 41a and 41b are directed downward, and the both end portions 41a and 41b are arranged front and rear in the movement direction D1. Coils 43a and 43b through which a current is passed are wound around the outer periphery of the end portions 41a and 41b, respectively. The core 42 also has, for example, a substantially U-shape, and is arranged so that both end portions 42a and 42b are directed upward, and the both end portions 42a and 42b are arranged front and rear in the movement direction D1. Coils 44a and 44b through which a current is passed are wound around the outer periphery of the end portions 42a and 42b, respectively. The end 41a of the core 41 and the end 42a of the core 42 pass, and the end 41b of the core 41 and the end 42b of the core 42 pass through the coarse bar H conveyed by the conveying roll 18, respectively. They are arranged so as to face each other up and down across the space. The widths of the cores 41 and 42 in the width direction of the coarse bar H (the width of the lower surface of the end portion 41a, the width of the lower surface of the end portion 41b, the width of the upper surface of the end portion 42a, and the width of the upper surface of the end portion 42b) May be about 1/2 to about 1/3 of the width of the coarse bar H. For example, when the width of the coarse bar H is about 1100 mm to 1800 mm, it may be about 600 mm, for example. On the other hand, the lengths of the cores 41 and 42 in the moving direction D1 (the width between the upstream edge of the lower surface of the end portion 41a and the downstream edge of the lower surface of the end portion 41b, and the upstream of the upper surface of the end portion 42a) The width between the side edge and the downstream edge on the upper surface of the end 42b) may be about 700 mm to 750 mm, for example.

  The coarse bar H on the transport roll 18 passes through between the end 41a and the end 42a and between the end 41b and the end 42b in this order, and is transported in the moving direction D1. . When the coarse bar H passes between the core 41 and the core 42, if current is supplied to the coils 43a, 43b, 44a, 44b, the magnetic flux penetrating in the thickness direction of the coarse bar H, that is, A magnetic flux Φ is generated from the end portion 41a toward the end portion 42a and from the end portion 42b to the end portion 41b. Due to the electromagnetic induction effect, as shown in FIG. (Eddy current) occurs. The rough bar H is heated by the energy of the induced current.

  In addition, the heating area | region by the heater 31 (32, 33) is the range where the induced current produced by the magnetic flux (PHI) of the cores 41 and 42 is distributed. The heating region is formed so that the rough bar H extends not only to the portion facing the end portions 41a, 41b, 42a, 42b but also to the outside of the end portions 41a, 41b, 42a, 42b. Further, since the induced current gradually decreases as the distance from the cores 41 and 42 increases, the amount of heating applied to the coarse bar H decreases as the distance from the cores 41 and 42 increases. Further, when a plurality of heaters 31, 32, 33 are provided side by side as in the present embodiment, the induced currents generated by the magnetic flux Φ of the cores 41, 42 overlap and influence each other, and the heating regions Can affect each other (interfere). In particular, the heating regions of adjacent heaters, that is, the heating region of the heater 31 and the heating region of the heater 32, and the heating region of the heater 32 and the heating region of the heater 33 tend to have a relatively large influence. Therefore, the output G of each heater 31, 32, 33 (that is, the magnitude of the current supplied to the coils 43a, 43b, 44a, 44b) can be set in consideration of the influence of the heating regions on each other. desirable. A method for considering the interference of the heating area will be described later.

As shown in FIG. 8, the heater 31 is configured to intensively heat the right side of the coarse bar H (the right side when viewed from the upstream side (first cutting machine 12 side) in the moving direction D1). That is, the cores 41 and 42 of the heater 31 face the right side of the cores 41 and 42 of the heaters 32 and 33 described later, that is, the portion close to the right edge side, which is one edge of the coarse bar H ( (In a position overlapping the right side of the coarse bar H in plan view). Specifically, the lower surface center portion (the lower surface center portion of the end portion 41a, the lower surface center portion of the end portion 41b) of the core 41 is more than the center portion P _C (width direction center portion) of the rough bar H in the width direction D2. disposed on the right side, also, the upper surface center portion of the core 42 (the upper surface center portion of the end portion 42a, the upper surface center portion of the end portion 42b) is adapted to be placed on the right side of the center portion P _C. At least, the central portion P _C and the first lateral portion P _{R (portion} where the temperature in the coarse bar H before soaking is relatively at high temperature) located between the right edge of the rough bar H and at a position opposed to between the central portion P _C, it is preferable to be able to move the core 41 (42).

Moreover, spacing is formed between the lower surface center portion of the core 41 of the central portion P _C and the heater 31 in a plan view (upper surface center portion of the core 42), i.e., the first interval X _R in the width direction D2, It is variable. That is, a heater moving mechanism (not shown) is driven by a control command of the control device 25, and the core 41 and the core 42 of the heater 31 are integrally formed relative to the coarse bar H along the width direction D2. It can be moved left and right.

The heater 32 is disposed so that the central portion and around P _C of the crude bar H can be heated intensively. In other words, the core 41, 42 (at a position overlapping the center portion P _C of the crude bar H in a plan view) as to face the center portion P _C is disposed. Specifically, the upper surface center portion of the lower surface center and the core 42 of the core 41 are arranged so that each faces the central part P _C.

The heater 33 is configured to intensively heat the left side of the coarse bar H (left side as viewed from the upstream side in the moving direction D1). That is, the cores 41 and 42 of the heater 33 are opposed to the left side of the cores 41 and 42 of the heaters 31 and 32, that is, the portion close to the left edge side which is the other edge of the coarse bar H (in plan view). At a position overlapping the left side of the coarse bar H). Specifically, the upper surface center portion of the lower surface center and the core 42 of the core 41, and is disposed on the left side of the center portion P _C. At least, the central portion P _C and the second lateral portion P _{L (the} portion where the temperature in the coarse bar H before soaking is relatively at high temperature) which is located between the left edge of the rough bar H and at a position opposed to between the central portion P _C, it is preferable to be able to move the core 41 (42).

Moreover, spacing is formed between the lower surface center portion of the core 41 of the central portion P _C and the heater 33 in a plan view (upper surface center portion of the core 42), i.e., the second interval X _L in the width direction D2, It is variable. That is, a heater moving mechanism (not shown) is driven by a control command of the control device 25, and the core 41 and the core 42 of the heater 33 are integrally formed along the width direction D2 relative to the coarse bar H. It can be moved left and right.

As mentioned above, two heaters 31 and 33 are adapted to be heated on the opposite side intensively to each other across the central portion P _C in the width direction of the rough bar H, the distance (shift amount) X _R , X _L can each be changed individually. Further, the core 41 (42) of the heater 31 and the core 41 (42) of the heater 33 are respectively disposed before and after the core 41 (42) of the heater 32 in the moving direction D1. In the moving direction D1, the distance between the core 41 (42) of the heater 31 and the core 41 (42) of the heater 32 and the distance between the core 41 (42) of the heater 32 and the core 41 (42) of the heater 33 Are set at approximately the same distance from each other. That is, the central portion of the core 41 provided in the heater 31 and the central portion of the core 41 provided in the heater 32 (the central portion between the lower surface front edge portion of the end portion 41a and the lower surface rear edge portion of the end portion 41b). , The central portion of the core 42 provided in the heater 31 (the central portion between the upper surface front edge portion of the end portion 42a and the upper surface rear edge portion of the end portion 42b) and the core provided in the heater 32 42, the distance between the central portion of the core 41 provided in the heater 32 and the central portion of the core 41 provided in the heater 33, the central portion of the core 42 provided in the heater 32. And the central portion of the core 42 provided in the heater 33 have the same distance Y.

  If the distance Y is too small, the heating regions by the heaters 31, 32, 33 interfere too strongly with each other, making it difficult to accurately control the heating amount by the heaters 31, 32, 33. It is desirable that the size be such that the interference between the heating regions is sufficiently reduced. On the other hand, if the distance Y is too large, the heat applied to the coarse bar H after being heated by the upstream heater 31 (32) in the moving direction D1 and before being heated by the downstream heater 32 (33). Will diffuse and the temperature of the coarse bar H will drop significantly, and in this case, too, it will be difficult to control the temperature distribution of the coarse bar H. Therefore, it is desirable that the distance Y be in a range that can be heated on the downstream side before the temperature is significantly reduced. For example, when the width of each core 41 (42) of the heaters 31, 32, 33 in the direction along the moving direction D1 is about 700 mm, the distance Y may be about 1400 mm. When the width of each core 41 (42) of the heaters 31, 32, 33 in the direction along the moving direction D1 is about 750 mm, the distance Y may be about 1500 mm.

The output G (the ratio α (= G / G _MAX ) with respect to the maximum output G _MAX ) of each heater 31, 32, 33 is variable. That is, the output of each heater 31, 32, 33 is adjusted by adjusting the magnitude of the current supplied to the coils 43a, 43b, 44a, 44b in each heater 31, 32, 33 by the control command of the control device 25. Each G is adjusted.

Next, the configuration of the temperature control system in the present embodiment will be described. As shown in FIG. 5, the temperature detectors 21, 22, and 23 are provided, for example, behind the rough rolling mill 11. That is, the temperature detection by the temperature detectors 21, 22, and 23 is performed on the coarse bar H placed on the transport roll 18 before the soaking process is performed in the soaking unit 13. . Further, as shown in FIG. 9, the temperature detectors 21, 22, and 23 are arranged in a line along the width direction D <b> 2 of the coarse bar H. Temperature detector 21 is arranged to detect the temperature T _C of the center portion P _C. Temperature detector 22, on the right side of the temperature detector 21, for example, is arranged to detect the temperature T _RE lateral portion P _R. Temperature detector 23, the left side of the temperature detector 21, for example, is arranged to detect the temperature T _LE of the side portion P _L. That is, a predetermined position h in the length direction of the coarse bar H (a position moved from the front end portion of the coarse bar H to the rear end side by a predetermined distance and substantially linear (or substantially) along the width direction D2. The temperature T _C , T _RE , and T _LE can be measured at the same time in a portion that forms a band), in other words, a portion that is the same point in a side view). The temperature detection values T _C , T _RE and T _LE are transmitted from the temperature detectors 21, 22 and 23 to the control device 25 (calculation unit 25 a described later). The temperature detector 21, 22 is not limited to those arranged differently, for example, a central portion _{P C} in the width direction of the rough bar H, the side portions _P R, a plurality of positions including _{P L} the temperature established the single thermometer that can measure the portion for detecting the temperature of the center portion P _C at the thermometer, the portion for detecting the temperature of the side portion P _R, detects the temperature of the side portion P _L These portions may be used as the temperature detectors 21, 22, and 23, respectively.

  As shown in FIG. 5, the speedometer 24 is provided, for example, behind the rough rolling mill 11. The detected value of the conveyance speed by the speedometer 24 is sequentially monitored by the control device 25 (calculation unit 25a described later).

  The control device 25 is, for example, a PLC (sequencer), and includes a calculation unit 25a that performs calculations such as calculation of various target values related to the heat equalization unit 13, and a heat equalization control unit 25b that controls the heat equalization unit 13. ing.

The arithmetic unit 25 a receives the temperature detection values T _C , T _RE , T _LE detected by the temperature detectors 21, 22, 23, the detection value of the conveying speed of the coarse bar H by the speedometer 24, and the like. Then, by monitoring the detected temperature value T _C and the transport speed, it can detect the temperature distribution of the center portion P _C in the longitudinal direction of the rough bar H. Further, by monitoring the detected temperature value T _RE and transport speed, it detects the temperature distribution in the lateral portion P _R in the longitudinal direction of the rough bar H, or monitoring the temperature detection value T _LE and the conveying speed it is, it is possible to detect the temperature distribution in the lateral portion P _L in the length direction of the rough bar H.

Also, temperature detection value _{T C, T RE, T LE} and, by monitoring the conveying speed, the central portion temperature difference between _{P C} and the side portions _{P R (T RE -T C)} , and a central portion temperature difference between P _C and the side portions _{P L} a _(T LE -T _C) can be detected. That is, the state of the temperature distribution in the width direction D2 of the coarse bar H can be estimated. For example, it can be determined whether or not the temperature distribution is asymmetrical. For example, as shown in FIG. 1, a plurality of predetermined positions h in the length direction of the coarse bar H, that is, substantially straight lines that are substantially parallel to each other along the width direction D2 of the coarse bar H, are predetermined in the length direction. Portions h set so as to be arranged at intervals (equal intervals) (in the example shown, h ₁ , h ₂ ,..., H _k ,..., H _n , k = 1, from the front end side) 2,..., N), the temperature distribution at each predetermined position h is confirmed by detecting the temperature detection values T _C , T _RE , and T _LE .

Further, the calculation unit 25a includes a target value α _t (output G target value G _t = α · G _MAX ), a target value X _Rt of the interval X _R , and an output ratio α of each heater 31, 32, 33, and It has a function of calculating a target value X _Lt of the interval X _L. That is, a program for calculating each target value α _t , X _Rt , and X _Lt is stored, and an operation is performed according to this program.

Next, the structure of the formula used for the program used for the calculation of the calculation unit 25a will be described. In deriving this equation, the inventor found the following.
1) As described above, if the outputs G (ratio α) of the three heaters 31, 32, 33 are made the same at the same position h in the length direction of the coarse bar H, both in the width direction and the length direction, Easy to control temperature distribution.
To improve the accuracy of 2) further temperature control, but moves the two right and left heater 31, 33, NoboriAtsushiryou [Delta] T _C of the central portion _{P C} At this time, the interval _X R, the effect of _{X L} And can be expressed by using a quadratic function of the intervals X _R and X _L.
3) Although the temperature rise amounts ΔT _RE and ΔT _LE at the side portions P _R and P _L are affected by the heating of the heaters 31, 32 and 33, the temperature rise amount differences ΔE _R and ΔE _L are equal to the interval X _R, it can be expressed using a linear function of X _L.
4) Using these relations, the output G (percentage alpha) and distance _X R, _{X L} of the heaters 31, 32, 33, it is possible to determine without the iterative calculation, the calculation time constant Can be processed in the PLC.

As shown in FIG. 10, in the calculation unit 25a, the target value ΔT _{Ct of} the temperature increase ΔT _C , the target value ΔE _Rt of the temperature increase difference ΔE _R , and the target value ΔE of the temperature increase difference ΔE _{L at} a certain predetermined position h. _Lt is obtained from the temperature detection values T _C , T _RE , T _LE and a target temperature T _t by soaking stored in a storage area provided in advance in the calculation unit 25a. That is, the temperature detection value _{T C} and the target temperature _{T t,} it is possible to obtain the target value [Delta] T _Ct of NoboriAtsushiryou _{ΔT C (= T t -T C} ). Further, the target value ΔE _Rt (= (T _t −T _C ) − (T _t −T _RE ) = T _RE −T _C ) of the temperature increase difference ΔE _R is obtained from the temperature detection values T _C and T _RE. Can do. Further, the detected temperature value _{T C,} from _{T LE,} the target value Delta] E _Lt of heated amount difference _{ΔE L (= (T t -T} C) - (T t -T LE) = T LE -T C) to obtain the Can do.

Target value Delta] E _Rt Atsushi Nobori amount difference Delta] E _R thus _obtained, the target value Delta] E _Lt of heated amount difference Delta] E _L, for example, the following three relational expressions as shown, i.e., the first relational expression (1) By substituting ΔE _R = ΔE _Rt , ΔE _R = ΔE _Rt , ΔE _L = ΔE _{Lt into} the second relational expression (2) and the third relational expression (3), as shown below The first equation (4), the second equation (5), and the third equation (6) are obtained. That is, a cubic simultaneous equation consisting of equations (4), (5), and (6) having three unknowns α _t , X _Rt , and X _Lt is obtained. Then, by solving these equations (4), (5), and (6) within the ranges of α _t ≧ 0, X _Rt ≧ 0, and X _Lt ≧ 0, the target value α _{t at} the predetermined position h, X _Rt and X _Lt can be calculated.

ΔT _C = (K1 + γ · K3 · X _R ² + γ · K3 · X _L ² + γ · K4) · α (1)
ΔE _R = (K2 + γ · K51 · X _R + γ · K52 · X _L + γ · K6) · α (2)
ΔE _L = (K2 + γ · K51 · X _L + γ · K52 · X _R + γ · K6) · α (3)

ΔT _Ct = (K1 + γ · K3 · X _Rt ² + γ · K3 · X _Lt ² + γ · K4) · α _t (4)
ΔE _Rt = (K2 + γ · K51 · X _Rt + γ · K52 · X _Lt + γ · K6) · α _t (5)
ΔE _Lt = (K2 + γ · K51 · X _Lt + γ · K52 · X _Rt + γ · K6) · α _t (6)

  Here, K1, K2, K3, K4, K51, K52, and K6 are coefficients (constants) that depend on the width of the coarse bar H. γ is a correction coefficient (constant) that takes into consideration the influence of the heating region by the heater 31, the heating region by the heater 32, and the heating region by the heater 33 (that is, the state of the heating region by the heater 31 and the heater 32). The coefficient relating to the state of the heating region and the state of the heating region by the heater 33).

The coefficient K1, K2, K3, K4, K51, K52, K6 is previously for rough bar H of various widths, spacing _X R, the relationship between the Atsushi Nobori amount of _{X L} and each of the heaters 31, 32, 33 It may be obtained by checking and stored in the calculation unit 25a. Also, the coefficient γ can be obtained in advance by, for example, examining the output ratio α of each heater 31, 32, 33 and the state of the heating area of each heater 31, 32, 33, etc., and stored in the computing unit 25a. It ’s fine. Incidentally, the coefficient γ is a coefficient depending on the distance Y and the maximum value of the temperature rise given to the rough bar H by the heater 31 (32, 33), and may be a constant value industrially. For example, in this embodiment, when the distance Y is about 1400 mm, the width of the core 41 (42) in the moving direction D1 is about 700 mm, and the maximum value of the temperature rise by the heaters 31 (32, 33) is 50 ° C. γ may be about 1.1.

Here, the theory from which the relational expression (1) is derived will be described. The graph shown in FIG. 11 shows that heating is performed using only one heater 50A (output G is the maximum output G _MAX (α = 1) (constant)) having substantially the same configuration as the heater 31 (32, 33). In the case of performing (see FIG. 12), the temperature rise given to the predetermined position h of the coarse bar H is simulated. In the graph shown in FIG. 11, the position of the core 41, 42 of the central portion _{P C} as a reference (0 mm), i.e., the lower surface center portion of the center portion _{P C} and the core 41 (the upper surface center portion of the core 42) the distance X ₁ [mm] in the width direction D2 between the horizontal axis, the vertical axis the NoboriAtsushiryou ΔT C _{(α = 1) 'given} to the central portion P _C of the position h by heating of the heater 50A Represents. Incidentally, the horizontal axis, the interval X ₁ is a bottom central portion of the core 41 if (top center of the core 42) is located on the right side of the center portion P _C is a positive value, when positioned on the left side is a negative value It is expressed as Further, in the example of FIG. 12, the width of the rough bar H is 1200 mm, the side portions _{P R,} the position of the right edge than 150mm inner rough bar H (central _{P C} side), the side portions _{P L} coarse The position was 150 mm inside from the left edge of the bar H. The width of the cores 41 and 42 in the width direction D2 was about 600 mm.

As shown in FIG. 11, the curve representing the change in NoboriAtsushiryou ΔT C _{(α = 1) 'when} changing the X _1, convex quadratic curve on which an apex of the X 1 _{= 0} ( Parabola). That is, NoboriAtsushiryou ΔT _{C (α = 1)} 'can be represented by the quadratic polynomial in which the _{X 1} and variable ^{_{(K3 · X 1 2 + K1}} , K1> 0, K3 <0). In other words, it is expressed by a quadratic function (ΔTC _{(α = 1)} ′ = K3 · X ₁ ² + K1) where X ₁ is an independent variable and the temperature increase ΔTC _{(α = 1)} ′ is a dependent variable. Can do.

Using the above relationship, the temperature given to the central portion P _C of a predetermined position h when sequentially heated predetermined position h by the three sets of heater 31, 32, 33 in the present embodiment (both alpha = 1) temperature An equation for the quantity ΔTC _{(α = 1)} can be derived. That is, when the outputs of the heaters 31, 32 and 33 are the same and constant (α = 1), the temperature increase amount ΔTC _{(α = 1)} given to the predetermined position h is three temperature increase amounts. the superimposed formula, that is, polynomial K3 _· ^X R 2 + K1 secondary to NoboriAtsushiryou _{(X R} variables given to the central portion _{P C} of the position h by heating the heater 31, ie, X _R = _{X 1} and then, the expression) derived by replacing the heater 50A to the heater 31, NoboriAtsushiryou given to the central portion _{P C} of the position h by heating of the heater 32 (constant K1, _{i.e., X} 1 = 0, and the equation) derived by replacing the heater 50A to the heater 32, the heater 33 a _(X L = -X ₁₎ NoboriAtsushiryou _{(X L} given to the central portion _{P C} of the position h by heating second-order polynomial to the variable K3 _· ^X L 2 + K1 That is, the X L ₌ -X _1, the heater 50A and equation) derived by replacing the heater 33, it (the approximation can be represented by a were linear combinations (sum by a constant multiple) polynomial). Therefore, the following expression (1-a) is obtained.
ΔTC _{(α = 1)} = K1 + γ · (K3 · X _R ² + K1) + γ · (K3 · X _L ² + K1)
= K1 + γ · K3 · X _R ² + γ · K3 · X _L ² + γ · K4 (1-a)
Thus, NoboriAtsushiryou ΔT _{C (α = 1)} can be represented by a two-variable function of _{X R} and _{X L} (second order polynomial).

Further, NoboriAtsushiryou [Delta] T C given to the central portion P _C by heating a single heater 50A in which the ratio of the output α variable _', the secondary polynomial and heater 50A where the X ₁ of the above as a variable (Multiplication), that is, α · (K3 · X ₁ ² + K1). Using this, when the predetermined position h of the coarse bar H is sequentially heated while the ratio α of the outputs of the heaters 31, 32, 33 is the same and variable with each other, the heater 31, 32, 33 heats the central portion. it can be derived equation for NoboriAtsushiryou [Delta] T _C given to P _C. That is, the temperature Yutakaryou [Delta] T _C In this case, the formula obtained by superimposing three heating amount, that is, the NoboriAtsushiryou (X _R given to the central portion P _C of the position h by heating of the heater 31 formula expressed using a ratio alpha of the output of the secondary of the polynomial and the heater 31 which is a variable, and α · (K3 · X R 2 + K1)), the central portion P _C of the position h by heating of the heater 32 (formula expressed by using a ratio of the output alpha of K1 and the heater 32, alpha · K1) is given NoboriAtsushiryou for the, temperature given to the central portion P _C of the position h by heating of the heater 33 represented by warm weight (formula expressed using a ratio alpha of the output of the X _L to a variable the quadratic polynomial and the heater 33, α · (K3 · X L 2 + K1)) and was allowed to linear combinations polynomials Can be approximated. From this, NoboriAtsushiryou [Delta] T _C, the ratio of the output alpha, spacing _X R, the first relational expression indicating a relationship between _{X L} (1) is obtained.
ΔT _C = α · K1 + γ · α · (K3 · X _R ² + K1) + γ · α · (K3 · X _L ² + K1)
= (K1 + γ · K3 · X _R ² + γ · K3 · X _L ² + γ · K4) · α
... (1)
In other words, [Delta] T _C can be expressed using a ΔT _{C (α = 1)} and _{α (ΔT C = α · ΔT} C (α = 1)).

Next, the theory from which the relational expression (2) is derived will be described. The graph shown in FIG. 13 is another graph related to the above simulation, and the horizontal axis is the same as that of FIG. One of the two curves in the graph, a curve representing the variation of NoboriAtsushiryou [Delta] T C described above _{(α = 1) ',} the other curves, the side at a predetermined position h in the case of changing the X ₁ against square section _{P R} is a curve representing the variation of NoboriAtsushiryou [Delta] T _RE given by heating of the heater 50A _{(α = 1) '.} When X 1 _{= 0} (i.e., when the central portion of the bottom surface of the core 41 (the upper surface center portion of the core 42) is in a position facing the center portion P _C), given to the central portion P _C at a predetermined position h heated amount difference between NoboriAtsushiryou (K1 [℃]) and heating amount given to the lateral portion P _R at a predetermined position h is K2 [° C.].

On the other hand, the graph shown in FIG. 14 shows two heaters 50B and 50C having substantially the same configuration as the heater 31 (32, 33) (the output G is the maximum output G _MAX (α = 1) (constant), respectively. ) In the case of heating (see FIG. 15), a simulation of the temperature rise difference given to the predetermined position h of the coarse bar H is performed. In the graph shown in FIG. 14, the central portion P _C and the lower surface center portion of the core 41 of the heater 50B (the upper surface center portion of the core 42) Interval X ₂ [mm] in the width direction D2 between the horizontal axis (core lower surface central portion 41 if (top center of the core 42) is located on the right side of the center portion P _C is a positive value, when positioned on the left side is a negative value), the heater 50B, the temperature caused by the heating of 50C temperature amount difference _{ΔE R (α = 1) '} ( the heater 50B, NoboriAtsushiryou ΔT _{C (α = 1} given to the central portion _{P C} at the position h by heating _50C)' and the heater 50B, 50C heating represents NoboriAtsushiryou given to the lateral portion P _R [Delta] T _RE heated amount difference between _{(α = 1) ')} as a vertical axis in a predetermined position h by. Five curves in the graph, changing the lower surface center portion of the core 41 of the central portion P _C and the heater 50C spacing X ₃ [mm] in the width direction D2 between the (upper surface center portion of the core 42) in four steps when in the _{(X 3 = -300, -200,} -100,0 ( lower surface center portion of the core 41 (a negative value if the upper surface center portion of the core 42) is located on the left side of the center portion _{P C)),} lines representing each relationship between the distance X ₂ and heated amount difference _{ΔE R (α = 1) '} , and a curve representing the average of these. In the example of FIG. 15, as in the example of FIG. 12, the width of the rough bar H is 1200 mm, the side portions _{P R,} the position of 150mm inside the right edge of the rough bar H (central _{P C} side) The side portion P _L is positioned 150 mm inside from the left edge of the coarse bar H. The width of the cores 41 and 42 in the width direction D2 was about 600 mm.

As shown in FIG. 14, the temperature increase amount difference ΔE _{R (α = 1)} ′ is smaller when X ₂ is a positive value than when it is a negative value. In other words, than the core 41 of the heater 50B which (42) is in a position near the left side with respect to the central portion P _C, it is better when it is in position near the right side decreases. In the range of X ₂ ≧ 0, the temperature increase difference ΔE _{R (α = 1)} ′ gradually decreases as X ₂ increases, that is, as the cores 41 and 42 of the heater 50B move to the right side. Furthermore, the curve of the temperature rise difference ΔE _{R (α = 1)} ′ (X ₂ ≧ 0) can be approximated to a straight line that decreases in proportion to an increase in X ₂ . That is, it can be represented (approximate) by a first order polynomial (K51 · X ₂ + K6 ′, K51 <0, K6 ′> 0, X ₂ ≧ 0) with X ₂ as a variable. In other words, it can be approximated by a linear function (ΔE _{R (α = 1)} ′ = K51 · X ₂ + K6 ′) with X ₂ as an independent variable and a temperature increase difference ΔE _{R (α = 1)} ′ as a dependent variable. . Further, considering the effect of X ₃ , the temperature increase difference ΔE _{R (α = 1)} ′ (X ₂ > 0, X ₃ <0) is a first-order polynomial (K51 · X3) with X ₂ and X ₃ as variables. X ₂ + K52 · | X ₃ | + K6). In other words, a linear function (ΔE _{R (α = 1)} ′ = K51 · X ₂ + K52 · | with X ₂ and X ₃ as independent variables and a temperature increase difference ΔE _{R (α = 1)} ′ as a dependent variable. X ₃ | + K6). Note that 'the influence of _{X 3} with respect to the very small, for example K52 ≒ 0, K6 ≒ K6' heated amount difference ΔE _{R (α = 1)} may be.

From the graph above in FIGS. 13 and 14, the central portion P _C of a predetermined position h when sequentially heated predetermined position h by the three sets of heater 31, 32, 33 in the present embodiment (both alpha = 1) can be derived equation for temperature rise amount difference between the heating amount given the temperature increase amount given to the side portion P _R at a predetermined position _{h ΔE R (α = 1)} . That is, when the outputs of the heaters 31, 32, and 33 are the same and constant (α = 1), the temperature rise difference ΔE _{R (α = 1)} generated at the predetermined position h is the difference between the two temperature rise differences. superimposed formula, that is, Atsushi Nobori amount difference caused by heating of the heater 32 (the aforementioned K2 (see FIG. 13), i.e., the X 1 _{= 0,} constant derived by replacing the heater 50A to the heater 32)
) And, the heater 31 and temperature increase amount difference caused in position h by heating of the heater 33 _(X R, X _L scratch was variable order polynomial _{K51 · X R + K52 · X} L + K6, _i.e., X R = _{X 2} , X _L = | X ₃ | and the equations derived by replacing the heaters 50B and 50C with the heaters 31 and 33, respectively, and a linearly coupled polynomial (can be approximated). That is, the following formula (2-a) is obtained.
ΔE _{R (α = 1)} = K2 + γ · ΔE _{R (α = 1)} ′
= K2 + γ · K51 · X _R + γ · K52 · X _L + γ · K6 (2-a)
Thus, temperature increase amount difference ΔE _{R (α = 1)} can be represented by a two-variable function of _{X R} and _{X L} (primary polynomial).

Further, the temperature rise difference ΔE _R 'generated at the predetermined position h by the heating of the two heaters 50B and 50C having the same and variable output ratio α is the first order using the above X ₂ and X ₃ as variables. It can be expressed by an equation expressed by using a polynomial and the output ratio α of each heater 50B, 50C, that is, α · (K51 · X ₂ + K52 · | X ₃ | + K6). Using this, when the predetermined position h of the coarse bar H is sequentially heated while the ratio α of the outputs of the heaters 31, 32, 33 is the same and variable with each other, the temperature rise difference ΔE _R generated at the predetermined position h. The formula for can be derived. That is, the temperature rise difference ΔE _R in this case is obtained by superposing two temperature rise amount differences, that is, the temperature rise difference (K2 and the output ratio α of the heater 32) generated by the heating of the heater 32. And the first order polynomial using the difference in temperature rise (X _R , _XL as a variable) and the output ratio α of the heaters 31, 33 (Α · (K51 · X _R + K52 · X _L + K6)) can be expressed by a linearly coupled polynomial expression (can be approximated). From this, heated amount difference Delta] E _R, the ratio of the output alpha, spacing X _R, the second relational expression indicating a relationship between X _L (2) is obtained.
ΔE _R = α · K2 + γ · ΔE _R '
= Α · K2 + γ · α · (K51 · X _R + K52 · X _L + K6)
= (K2 + γ · K51 · X _R + γ · K52 · X _L + γ · K6) · α (2)
In other words, ΔE _R can be expressed using ΔE _{R (α = 1)} and α (ΔE _R = α · ΔE _{R (α = 1)} ).

Next, the theory from which equation (3) is derived will be described. Equation (3) can be derived in substantially the same manner as equation (2). For example, in the graph shown in FIG. 12, the curve representing the change in NoboriAtsushiryou given to the lateral portion P _L at a predetermined position h when changing the distance X ₁ of the heater 50A, the side of the predetermined position h against the curve representing the change in NoboriAtsushiryou given to parts P _R, represented in a line symmetric shape around the X 1 _{= 0.} Therefore, NoboriAtsushiryou the heater 50A (X 1 = ₀₎ heating amount given to the central portion P _C of a predetermined position h from the temperature increase amount given to the lateral portion P _L at a predetermined position h The difference is also K2 [° C.]. Also, a certain proportion of the output alpha two sets of heater 50B was (alpha = 1), NoboriAtsushiryou [Delta] T C given to the central portion P _C of a predetermined position h in the case of heating by 50C _{(α = 1)} The temperature increase amount difference ΔE _{L (α = 1)} ′ between “and the temperature increase amount ΔT _{LE (α = 1)} ” given to the side portion P _{L at} the predetermined position h is a variable of X ₂ and X ₃ . The first order polynomial (K51 · | X ₃ | + K52 · X ₂ + K6) can be expressed (can be approximated).

From the above equations, the Atsushi Nobori amount given to the central portion P _C of a predetermined position h when sequentially heated predetermined position h by the three sets of heater 31, 32, 33 in the present embodiment (both alpha = 1) It is possible to derive an expression relating to the temperature increase amount difference ΔE _{L (α = 1) from} the temperature increase amount given to the side portion P _L at the predetermined position h. That is, when the outputs of the heaters 31, 32, 33 are the same and constant (α = 1), the temperature rise difference ΔEL _{(α = 1)} generated at the predetermined position h is the difference between the two temperature rise differences. Overlaid formula, that is, a temperature rise difference (K2) caused by heating of the heater 32 and a temperature rise difference (X _R , X _L) generated at a predetermined position h by heating of the heater 31 and the heater 33 as variables. Of the polynomial K51 · X _L + K52 · X _R + K6, ie, X _R = X ₂ , X _L = | X ₃ | and the heaters 50B and 50C are replaced by the heaters 31 and 33, respectively, and the linear equation) It can be represented (approximate) by a combined polynomial. That is, the following formula (3-a) is obtained.
ΔE _{L (α = 1)} = K2 + γ · ΔE _{L (α = 1)} ′
= K2 + γ · K51 · X _L + γ · K52 · X _R + γ · K6 (3-a)
Thus, temperature increase amount difference ΔE _{L (α = 1)} can also be represented by a two-variable function of _{X R} and _{X L.}

Further, the temperature rise difference ΔE _L ′ generated at the predetermined position h by the heating of the two heaters 50B and 50C having the same and variable output ratio α is a first order using the above X ₂ and X ₃ as variables. It can be expressed by an equation expressed by using a polynomial and the output ratio α of each heater 50B, 50C, that is, α · (K51 · | X ₃ | + K52 · X ₂ + K6). Using this, when the predetermined position h of the coarse bar H is sequentially heated while the ratio α of the outputs of the heaters 31, 32, 33 is the same and variable with each other, the temperature rise difference ΔE _R generated at the predetermined position h. The formula for can be derived. In other words, the temperature increase amount difference ΔE _R in this case is an equation obtained by superimposing two temperature increase amount differences, that is, the temperature increase amount difference (α · K2) generated by the heating of the heater 32, and the heater 31 and the heater 33. heating amount difference caused by heating _(X R, _X formula expressed using a ratio alpha of the output of the _L and the variable was first order polynomial and the heater _{31,33, α · (K51 · X} L + K52 · X R + K6 )) Can be expressed by a linearly coupled polynomial (can be approximated). Than this, heated amount difference Delta] E _L, the ratio of the output alpha, spacing X _R, the third relational expression indicating the relationship X _L (3) is obtained.
ΔE _L = α · K2 + γ · ΔE _L '
= Α · K2 + γ · α · (K51 · X _L + K52 · X _R + K6)
= (K2 + γ · K51 · X _L + γ · K52 · X _R + γ · K6) · α (3)
In other words, ΔE _L can be expressed using ΔE _{L (α = 1)} and α (ΔE _L = α · ΔE _{L (α = 1)} ).

That is, according to the present embodiment, the output ratio α of the heater 31 when the cores 41 and 42 are arranged to face the predetermined position h, and the cores 41 and 42 with respect to the predetermined position h. The output ratio α of the heater 32 when arranged so as to oppose each other, and the output ratio α of the heater 33 when the cores 41 and 42 are arranged so as to oppose the predetermined position h, respectively. by setting the mutually same value at each predetermined position h, and variables used to control the temperature distribution of the coarse bar _H, α, X R, can be reduced to only three X _{L. Then,} α, X R, a relatively simple relationship for _{X L (1), (2} ), (3) using _a, α, X R, the target value of _{X L α t, X Rt,} X Lt Can be easily calculated. Therefore, the temperature distribution can be easily controlled.

The simultaneous equations composed of the above equations (4), (5), and (6) can be directly solved by the explicit method. That is, the target values α _t , X _Rt , and X _Lt are obtained by an explicit method. In this case, there is an effect that the calculation time in the calculation unit 25a, that is, the calculation time for calculating the target values α _t , X _Rt , and X _Lt for each predetermined position h is constant. That is, the target values α _t , X _Rt , and X _Lt are calculated at a constant cycle, and the heaters 31, 32, and 33 can be controlled at a constant cycle (output ratio α and intervals X _R and _XL ). For example, when fitting calculation or implicit method is used, the calculation time required to calculate the target values α _t , X _Rt , and X _Lt for each predetermined position h is different for each predetermined position h (ie, for example, temperature detection value T _C , T _RE , and T _LE ) greatly differ, and calculation within a certain time and control with a certain period become impossible.

The soaking control unit 25b transmits a control signal to each of the heaters 31, 32, 33 based on data such as the target values α _t , X _Rt , X _Lt calculated by the calculation unit 25a. That is, as the output of the heaters 31, 32, 33 becomes equal to the target value calculated in the calculating section 25a (as percentage alpha is the target value alpha _t), the coils 43a of each heater 31, 32, 33, 43 b, 44a, function of adjusting the magnitude of the current to be supplied to 44b, the ability to regulate the driving of the heater moving mechanism (not shown) of the heater 31 so that the distance X _R is the calculated target value X _Rt, and has the function of adjusting the driving of the heater moving mechanism (not shown) of the heater 33 so that the target value X _Lt interval X _L is calculated.

  Next, the hot rolling method of the steel H performed by the hot rolling equipment 1 configured as described above will be described. First, the slab H is heated in the heating furnace 10. The slab H heated in the heating furnace 10 is transported to the roughing mill 11 by the transporting roll 18 and rough-rolled and processed into a rough bar H.

After the rough rolling, the rough bar H is moved from the roughing mill 11 to the cutting machine 12 by the conveying roll 18 and further from the cutting machine 12 to the soaking section 13 with the length direction set to the moving direction D1, It is transported at a predetermined transport speed. While the coarse bar H is conveyed toward the cutting machine 12, the temperature detectors 21, 22, and 23 sequentially detect the temperature of the coarse bar H. That is, the temperatures at a plurality of positions in the length direction of the coarse bar H, that is, the predetermined positions h (h1, h2,...) (See FIG. 1) are sequentially detected from the front end side. In addition, three temperature detection values T _C , T _RE , and T _{LE at} each predetermined position h are detected simultaneously. The temperature detection values T _C , T _RE , and T _LE of the temperature detectors 21, 22, and 23 are sequentially transmitted to the calculation unit 25 a of the control device 25.

In the calculation unit 25a, the conveyance speed of the coarse bar H transmitted from the speedometer 24 and the temperature detection values T _C , T _RE , and T _LE are detected. Further, the detected temperature at each predetermined position h _{T C,} T _RE, based on _{T LE,} the target value Delta] E _Rt target value [Delta] T _Ct, heated amount difference Delta] E _R of the temperature Yutakaryou [Delta] T _C at each predetermined position h , The target value ΔE _Lt of the temperature increase difference ΔE _L is calculated, and the calculation using the above formulas (1), (2), (3) is performed. That is, for each predetermined position h, the target value alpha _t the proportion of the output at the soaking section 13, the target value _{X Rt} interval _{X R,} the target value _{X Lt} distance _{X L} obtained respectively. In this way, the target values α _t , X _Rt , and X _Lt for each predetermined position h obtained by the calculation unit 25a are sequentially transferred to the soaking control unit 25b.

Note that the calculation unit 25a calculates target values α _t , X _Rt , and X _Lt for each predetermined position h by a direct solution. Therefore, the target values α _t , X _Rt , and X _Lt for each predetermined position h can be calculated at regular time intervals, and the data of the target values α _t , X _Rt , and X _Lt for each predetermined position h are obtained from the calculation unit 25a. The heat equalization control unit 25b is sequentially transferred at a constant cycle. That is, a control command can be transmitted from the soaking control unit 25b to each of the heaters 31, 32, 33 at a constant period. That is, the heaters 31, 32, and 33 can be favorably controlled while keeping the control cycle of the sequence control by the control device 25 constant.

In the soaking part 13, the rough bar H is moved along the moving direction D1, and a plurality of predetermined positions h are made to enter in order from the front end side (that is, in the order of the parts h ₁ , h ₂ ,...). It will be. The coarse bar H is heated in this order by the heaters 31, 32, 33 while being moved along the moving direction D1. Ratio alpha, spacing _X R, _{X L} of the output of each heater 31, 32, 33, with the movement of the coarse bars H (position h), are sequentially controlled. That is, the calculating section 25a so that the target value alpha _t ratio alpha output obtained respectively for each predetermined position h is achieved by the control of the soaking controller 25b, in each of the heaters 31, 32, 33 The magnitude of the current supplied to the coils 43a, 43b, 44a, 44b is adjusted sequentially. Further, as the target value _{X Rt} interval _{X R} obtained respectively for each position h by calculating the arithmetic unit 25a, the target value _{X Lt} distance _{X L} is realized, the illustration of the heaters 31 and 33 The driving of the heater moving mechanism that is not performed is sequentially adjusted.

For example, the predetermined position h _k will be described as a representative. The predetermined position h _k is first moved to a position (FIG. 16) sandwiched between the cores 41 and 42 of the heater 31. In other words, the core 41 of the heater 31 is disposed so as to face the right side of the predetermined position _{h k.} In this case, the ratio α of the output of the heater 31, (calculated on the basis of a predetermined position _{h k} detected temperature value _T C obtained _for, T _{RE, T LE)} to the predetermined position _{h k} obtained for the target value It is matched to the α _t. The distance _{X R} is aligned with the target value _{X Rt} determined for a given position _{h k.} By heat is applied centrally by such a heater 31, in the vicinity of a predetermined position h _k and before and after, the temperature of the right side is intensively heated the central portion P _C.

Next, the predetermined position h _k is moved to a position (FIG. 17) sandwiched between the cores 41 and 42 of the heater 32. In other words, the core 41 of the heater 32, (in other words so as to face the central portion of the predetermined position _{h k,} adjacent in the width direction D2 with respect to the portion that passes between the core 41 and the heater 31 (Or so as to face the overlapping part). At this time, the output ratio α of the heater 32 is set to the target value α _t obtained for the predetermined position h _k (in other words, at a position _{where the} predetermined position h _k is sandwiched between the cores 41 and 42 of the heater 31). And the same value as the target value α _t of the heater 31 at the time. By heat is applied centrally by such a heater 32, in the vicinity of a predetermined position h _k and before and after, the temperature of the center portion P _C vicinity is intensively heated.

Thereafter, the predetermined position h _k is moved to a position (FIG. 18) sandwiched between the cores 41 and 42 of the heater 33. That is, the cores 41 and 42 of the heater 33 are opposed to the left side of the predetermined position h _k (in other words, between the cores 41 and 42 of the heater 31 and between the cores 41 and 42 of the heater 32). It arrange | positions so that it may oppose the part which adjoins or overlaps in the width direction D2 with respect to a part. At this time, the output ratio α of the heater 33 is set at the target value α _t obtained for the predetermined position h _k (in other words, at a position _{where the} predetermined position h _k is sandwiched between the cores 41 and 42 of the heater 31). is the same value as the target value alpha _t of the heater 31 when the, also, and the target value alpha _t of the heater 32 when the predetermined position h _k is disposed at a position sandwiched between the core 41 and the heater 32 The same value). Further, the interval X _L is set to the target value X _Lt obtained for the predetermined position h _k . By such intensive heat by the heater 33 in the state is given, in the vicinity of a predetermined position h _k and before and after, the temperature of the left side is intensively heated the central portion P _C.

Thus, by a predetermined position _{h k} are sequentially heated by the heater 31, 32, 33, in the central part _{P C} of a predetermined position _{h k,} heating of the obtained target value [Delta] T _Ct for a given position _{h k} is (See FIG. 2). In addition, the side portions _{P R} at a predetermined position _{h k,} NoboriAtsushiryou [Delta] T _C NoboriAtsushiryou [Delta] T _REt from the target value [Delta] T _Ct by subtracting the target value Delta] E _Rt of heated amount difference Delta] E _R, i.e., [Delta] T _Ct A temperature increase of -ΔE _Rt is given. The side portions _{P L} at a predetermined position _{h k,} NoboriAtsushiryou [Delta] T _LET minus the target value Delta] E _Lt of heated amount difference Delta] E _L from the target value [Delta] T _Ct of NoboriAtsushiryou [Delta] T _C, i.e., ΔT _Ct -ΔE A temperature rise amount of _Lt is given. As a result, the central portion P _C , the side portion P _R , and the side portion P _{L at} the predetermined position h _k are each heated to the target temperature T _t . Depending on Similarly, other portions at a predetermined position h _k, i.e., between the central portion P _C and the side portions P _R, also between the center portion P _C and the side portions P _L, the width direction position Thus, an appropriate temperature increase amount is given. Therefore, the temperature of the whole between the side portions P _R at a predetermined position h _k to the side portion P _L is equalized to be substantially the target temperature T _t.

Similarly, heating by the heaters 31, 32, 33 is sequentially performed at other positions h ₁ , h ₂ ,... Other than the predetermined position h _k . That is, the target values ΔT _Ct , ΔE _Rt , ΔE _Lt are sequentially obtained over the length direction of the coarse bar H, and based on these target values ΔT _Ct , ΔE _Rt , ΔE _Lt , the target value α _t (G _t ), X _Rt , X _Lt are obtained, and the intervals X _R , _XL are adjusted while the ratio α (output G) of the heaters 31, 32, 33 is adjusted to be the same for each predetermined position h. The

Thus, by the heaters 31, 32, 33, each predetermined position h is raised appropriately, the coarse bar H is the inner portion excluding the right and left edges, i.e. the side portion _P R, between the _{P L,} FIG. 2, the temperature distribution in the width direction D2 is made uniform. Further, as each predetermined position h is moved in the moving direction D1 while being sequentially heated by the heaters 31, 32, 33, as shown by the dotted line in FIG. The distribution is made uniform sequentially.

By soaking in the soaking part 13 as described above, the temperature distribution of the coarse bar H is substantially uniformized to a predetermined target temperature T _t except for the left and right edges. Further, as described above, in the soaking process, the target value α _t of the output ratio α of each heater 31, 32, 33 is set at each predetermined position h (that is, the rough bar H is set on the right edge side, for example). Control is performed so that they are the same for each part that is substantially the same in the side view. The time change of the output ratio α of the heater 32 is the same as the time change of the output ratio α of the heater 31, but with respect to the time change of the ratio α of the heater 31 only by the time corresponding to the conveying speed of the coarse bar H. It will change later. That is, for example, the predetermined position h _k is the same as the ratio α of the heater 31 while being delayed by the time required to move from the position facing the cores 41, 42 of the heater 31 to the position facing the cores 41, 42 of the heater 32. To change. Similarly, the time change of the output ratio α of the heater 33 is the same as the time change of the ratio α of the heater 32, but the time of the output ratio α of the heater 32 is equal to the time corresponding to the conveying speed of the coarse bar H. It changes with a delay with respect to the change. That is, for example, the predetermined position h _k is the same as the ratio α of the heater 32 while being delayed by the time required to move from the position facing the cores 41, 42 of the heater 32 to the position facing the cores 41, 42 of the heater 33. To change.

After soaking, the coarse bar H is conveyed to the edge heater 15. The edge heater 15, the left and right edges of the crude bars H (side portions P _R, outside portion of P _L) is heated. Thus, as indicated by a chain line in FIG. 2, to the left and right edges of the crude bar H, it is substantially equalized to a predetermined target temperature T _t. In this way, the temperature distribution of the entire coarse bar H can be suitably made uniform.

  After the edge is heated in the edge heater 15, the rough bar H is conveyed to the finish rolling mill group 16 and finish-rolled to a predetermined target thickness. The finish-rolled steel sheet H is wound around the winder 17 in a coil shape. Thus, a series of hot rolling processes is completed. In the hot rolling line L, a plurality of steel materials H are continuously conveyed at a predetermined pitch, and the hot rolling process is performed on each steel material H.

  The preferred embodiment of the present invention has been described above with reference to the accompanying drawings, but the present invention is not limited to such an example. It is obvious for those skilled in the art that various changes and modifications can be conceived within the scope of the technical idea described in the claims. It is understood that it belongs to.

  For example, in the above embodiment, the hot rolling line L includes devices such as the heating furnace 10, the roughing mill 11, the cutting machine 12, the soaking unit 13, the edge heater 15, the finishing mill group 16, and the winder 17. Although the arrangement is provided in this order in the movement direction D1, the arrangement of the devices is not limited to this.

In the above embodiments, the target temperature of the coarse bar H in the heating of the soaking section 13 is set to a predetermined target temperature T _t, the target temperature and the both end portions P _L in the central portion P _C of the crude bar _H, P _R The target temperatures at may be different from each other. The target temperature for heating by the heater 31 and the target temperature for heating by the heater 32 may be different from each other. Further, the target temperatures at the predetermined positions h may be different from each other. That is, the target state of the temperature distribution after performing the soaking process by the soaking unit 13 and the edge heating process by the edge heater 15 is the entire length direction and the entire width direction as shown in FIGS. The temperature distribution is not limited to a uniform temperature distribution, and an arbitrary temperature distribution can be set as a target.

In the above embodiment, a central portion heater for the heater 32 heats the central portion P _C, the heater 31, 33 lateral portions P _L, was to be a side heater for heating the P _R side, It is not limited to such a form. The center heater may be any one of the three heaters 31, 32, 33. For example, the heater 33 may be a center heater and the other two heaters 31, 32 may be side heaters. good. In particular, for example, when the descaling device is not located in front of the soaking part 13 (upstream in the moving direction D1) but only behind the soaking part 13 (downstream in the moving direction D1), etc. There is a possibility that the scale peels off from the coarse bar H in the hot part 13 (particularly the rearmost heater) and rolls up, adversely affecting the heater and the like. Therefore, maintainability improves if the rearmost heater is not fixed and moved in the center.

In the above embodiment, the temperature distribution in the width direction D2 of the rough bar H before the soaking by the soaking part 13 is asymmetric in the left and right directions, but at any one of the predetermined positions h, for example, the predetermined position h _k . When the temperature difference between the right side temperature T _RE and the left side temperature T _LE is small, the temperature distribution in the width direction D2 at the predetermined position h _k may be considered to have good left-right symmetry. Further, the calculating unit 25a, the position _h heating amount difference in _k Delta] E _R target value _{ΔE Rt (= T RE -T C} ) between the target value Delta] E _Lt of heated amount difference ΔE _{L (= T LE} - T _C ) may be calculated as the same target value ΔE _t (= ΔE _Rt = ΔE _Lt ). In this way, it is possible to a target value _{X Lt} of the target value _{X Rt} and spacing _{X L} interval _{X R} on the same target value _{X t.} That is, the unknown can be reduced to two (α _t , X _Rt = X _Lt = X _t ), and the relational expression used to derive the unknown can be reduced to two. That is, the following two relational expressions, that is, the first special relational expression (1) ^* and the second special relational expression (2) that can be used when the left-right symmetry of the temperature distribution at the predetermined position h is good. ^*, the target value [Delta] t _Ct of NoboriAtsushiryou [Delta] t _C, and, by substituting the target value Delta] E _t of heated amount difference Delta] E _R, Delta] E _L, equation ⁽⁴⁾ shown below *, two consisting of ^{(5) *} The target values α _t and X _t (special solutions) can be calculated by solving the following simultaneous equations. In (1) ^* and (2) ^* , X = X _R = X _L and ΔE = ΔE _R = ΔE _L.
ΔT _C = (K1 + 2 · γ · K3 · X ² + γ · K4) · α (1) ^*
ΔE = (K2 + (γ · K51 + γ · K52) · X + γ · K6) · α
= (K2 + γ · K5 · X + γ · K6) · α (2) ^*
ΔT _Ct = (K1 + 2 · γ · K3 · X _t ² + γ · K4) · α _t (4) ^*
ΔE _t = (K2 + γ · K5 · X _t + γ · K6) · α _t (5) ^*
In other words, [Delta] T _C can be expressed using the X of quadratic polynomial (K1 + 2 · γ · K3 · X 2 + γ · K4) α, ΔE R is X primary polynomial (K2 + γ · K5 X + γ · K6) and α can be used for the expression.

In this way, by the same target value of the target value and the distance X _L interval X _R, can be further simplified to equation, calculation can be easily performed. For example, as shown in the graph of FIG. 19, the linearity of a part of the curve indicating the temperature increase difference ΔE _{R (α = 1)} ′ is improved. That is, compared with the curve shown in FIG. 14, the curve becomes closer to a straight line, and an approximate straight line (ΔE _{R (α = 1)} ′ = K5 · X ₂ + K6 _{) of} the temperature rise difference ΔE _{R (α = 1)} ′. ) Less error. Although not shown, the linearity of a part of the curve showing the temperature increase difference ΔE _{L (α = 1)} ′ is also improved. That is, an error from the approximate straight line of the temperature increase difference ΔE _{L (α = 1)} ′ is reduced. Therefore, the target values α _t and X _t can be calculated appropriately, and the temperature distribution of the coarse bar H can be adjusted with higher accuracy.

Note that the graph of FIG. 19 shows the difference in temperature rise and temperature rise given to the coarse bar H when heating is performed with _two heaters 50B and 50C (α = 1, X ₂ = −X ₃ ). This is a simulation. In the graph of FIG. 19, the horizontal axis is the same as the horizontal axis of the graph of FIG. Three curves in the graph, NoboriAtsushiryou given to the central portion _{P C ΔT C (α = 1} ) '(= 2 · K3 · X 2 2 + γ · K4), with respect to the lateral portion _{P R} given Te NoboriAtsushiryou _{ΔT RE (α = 1) '} , heated amount difference _{ΔE R (α = 1)'} (= ΔT C (α = 1) '-ΔT RE (α = 1)') to represent each ing.

Further, a control method based on the relational expressions (1), (2), (3) (the first control method, that is, the target value α _t using the relational expressions (1), (2), (3)). , _{X Rt,} and a method) for calculating the _{X Lt,} equation ⁽¹⁾ *, ⁽²⁾ a method (a second method of controlling based on ^*, i.e., equation ⁽¹⁾ *, ^{(2) *} And the method of calculating the target values α _t and X _t using) according to the temperature distribution state at each predetermined position h. In this case, for example, it may be selected which control method is used depending on whether or not the temperature difference between the temperature T _RE and the temperature T _{LE at} each predetermined position h is within a predetermined range. For example, if the temperature difference at the predetermined position h _k is 2 ℃ or more _{(| T RE -T LE | ≧} 2 ℃, i.e., if it can be determined that the left and right symmetry of the temperature distribution is not good), the first control When the temperature difference at the predetermined position h _k is less than 2 ° C. (| T _RE −T _LE | <2 ° C.) using the method (that is, when it is determined that the temperature distribution has good left-right symmetry), Two control methods may be used. Further, such a determination may be performed in the calculation unit 25a based on the temperature detection values T _RE and T _LE .

Also, for example, when it is known in advance that the temperature distribution of the coarse bar H is good, the first control method and the second control method are not used properly, and only the second control method is performed. Also good. That is, while always the same size of the size and spacing X _L interval X _R, in accordance with the movement of the rough bar H is varied, may be subjected to heat.

The inventors conducted a heating experiment of the coarse bar H using the heaters 31, 32, and 33. The width of the coarse bar H was 1100 mm to 1800 mm. The thickness of each coarse bar H was 30 mm. The positions of the side portions P _R and P _L were both 150 mm inside from the right edge (left edge) of the coarse bar H. Further, the distance Y in the soaking part 13 is 1400 mm, the width of each core 41 (42) of the heaters 31, 32, 33 in the width direction D2 is 600 mm, and the maximum temperature rise amount by the heaters 31 (32, 33) is 50. It was assumed to be ° C.

As the PLC used for the control device 25, a PLC capable of executing 20K steps in a cycle of 50 ms was used. In the sequence control program executed by the PLC, for example, in the program of the control method (control method based on the relational expressions (1) ^* and (2) ^* ) when the temperature distribution of the coarse bar H is good, first, equation ^{(5) *} _X t a _{(= X} Rt = X _Lt) derives the expressed expression as a function of alpha _t from the expression into equation ^{(4) *,} to seek now to alpha _t I made it. Then, it was to obtain the X _t by substituting the α _t. In this case, the number of steps is about 100 or less, and the number of steps is constant. The calculation time is about 0.25 ms or less, and this calculation time is also constant.

(Experiment 1)
An example is shown in which a heating experiment is performed by a control method when the temperature distribution of the coarse bar H is good, that is, by a control method based on the relational expressions (1) ^* and (2) ^* . The width of the coarse bar H was about 1200 mm, the thickness was about 30 mm, and the material was low-carbon aluminum silicon killed steel. Then, the soaking process is performed by the heaters 31, 32, 33 over the length direction of about 40 m or more. Note that the constants K1, K2, K3, K4, K5, and K6 of the relational expressions (1) ^* and (2) ^* are the values for the width of 1200 mm shown in the table of FIG. Incidentally, the values shown in FIG. 20 are examples of values obtained by the present inventors through experiments, simulations, and the like.

First, the temperature of the crude bar H before soaking, a plurality of locations of the center portion P _C, a plurality of locations of the side portion P _R, measured at a plurality of positions of the side portions P _L, the length direction of the center portion P _C temperature distribution in the temperature distribution in the length direction of the side portion P _R, the temperature distribution in the length direction of the side portions P _L were investigated, respectively. The result is shown in FIG. Further, from these results, the standard deviation of the temperature distribution of the center portion P _C, the standard deviation of the temperature distribution in the lateral portion P _R, the standard deviation of the temperature distribution in the lateral portions P _L, the standard deviation of the temperature distribution in the width direction Examined. As a result, the standard deviation of the temperature in the length direction was about 7.2 ° C. The standard deviation of the temperature in the width direction was about 4.0 ° C.

Next, equation ⁽¹⁾ *, ⁽²⁾ after soaking by the heater 31, 32 and 33 while controlling based on ^*, the temperature of the crude bar H, a plurality of locations of the center portion _{P C,} side a plurality of locations of square section P _R, measured at a plurality of positions of the side portions P _L, the temperature distribution in the longitudinal direction of the central portion P _C, the temperature distribution in the length direction of the side portion P _R, the side portions P _L The temperature distribution in the length direction of each was investigated. The result is shown in FIG. Further, from these results, the standard deviation of the temperature distribution of the center portion P _C, the standard deviation of the temperature distribution in the lateral portion P _R, the standard deviation of the temperature distribution in the lateral portions P _L, the standard deviation of the temperature distribution in the width direction Examined. As a result, the standard deviation of the temperature in the length direction was about 3.3 ° C. The standard deviation of the temperature in the width direction was about 3.6 ° C.

Based on the above results, the standard deviation of the temperature in the length direction of the coarse bar H, that is, the temperature variation in the length direction, is subjected to soaking by control based on the relational expressions (1) ^* and (2) ^*. As a result, it was found that it can be greatly reduced. In addition, the standard deviation of the temperature in the width direction of the rough bar H, that is, the temperature variation in the width direction, is also greatly reduced by performing soaking with control based on the relational expressions (1) ^* and (2) ^*. I knew it was possible.

(Experiment 2)
An example in which a heating experiment using a control method in the case where the temperature distribution of the coarse bar H is not good, that is, a control method based on the relational expressions (1), (2), and (3) will be described. The conditions and the like of the coarse bar H were the same as those shown in Experiment 1 above. The values shown in the table of FIG. 23 were used for the constants K1, K2, K3, K4, K51, K52, and K6 in the relational expressions (1), (2), and (3).

After performing soaking with the heaters 31, 32, 33 while controlling the coarse bar H based on the relational expressions (1), (2), (3), the center of the coarse bar H is the same as in Experiment 1. temperature distribution and standard deviation in the length direction of the parts P _C, the temperature distribution in the length direction of the side portion P _R and its standard deviation, the temperature distribution in the length direction of the side portions P _L and the standard deviation, respectively Examined. As a result, the standard deviation of the temperature in the length direction was about 3.0 ° C. The standard deviation of the temperature in the width direction was about 2.5 ° C.

  From the above results, even by performing soaking by control based on the relational expressions (1), (2), and (3), the temperature variation in the length direction of the coarse bar H and the temperature variation in the width direction are It was found that each can be greatly reduced.

(Comparative example)
The present inventors have studied a method for retrieving α _t, X _Rt , and X _Lt from a matrix prepared in advance by applying the method disclosed in Patent Document 1 (Japanese Patent Laid-Open No. 2004-195497). The following findings were obtained. For example, when the control ranges of the temperature increase amount ΔT _Ct , the temperature increase amount differences ΔE _Rt , and ΔE _Lt are 150 ° C. (1 ° C. intervals), the data of the temperature increase amount ΔT _Ct , the temperature increase amount differences ΔE _Rt , ΔE _Lt are Since 150 pieces are required for each, a storage area capable of storing at least 150 × 150 × 150 = 3375000 pieces of data is required. In this case, since the storage capacity is insufficient in the PLC, it is necessary to store the matrix in a computer provided separately from the PLC. That is, it is necessary to retrieve α _t, X _Rt , and X _Lt from the matrix in the computer and transfer the results to the PLC. In this case, it is considered that the total processing time required for a series of processes (including the calculation time required for the search and the transfer time) is about 1 second. Therefore, it can be seen that the time intervals for obtaining the target values α _t, X _Rt , and X _Lt are significantly longer than in the method of the present embodiment.

When the coarse bar H is moving at a speed of, for example, 60 m / min (that is, 1 m / sec), in the control method of the present embodiment, for example, about 0.05 m in the length direction of the coarse bar H. It is possible to adjust the interval X _R of the heater 31, the interval X _{L of} the heater 33, and the output ratio α of each heater 31, 32, 33 (that is, the pitch of the predetermined position h is set to about 0.05 m). However, in the control method using the search of the matrix, it is possible to adjust only about every 1 m at the minimum (that is, the pitch of the predetermined position h can only be set to about 1 m at the minimum). That is, according to the method of the present embodiment, the pitch of the predetermined position h can be reduced to about 1/20 as compared with the control method using matrix search, in other words, the temperature distribution in the length direction. It can be said that the controllability can be improved about 20 times. As described above, according to the method of this embodiment, the temperature distribution can be controlled with extremely high accuracy.

  The present invention can be applied to a method of heating a steel material.

It is a schematic plan view of a coarse bar. It is a graph which shows the temperature distribution in the width direction of a rough bar. It is a graph which shows the temperature distribution in the length direction of a rough bar. It is a graph which shows the relationship between temperature rising amount and temperature rising amount difference. It is a schematic diagram which shows the outline of a structure of a hot rolling facility. It is a schematic longitudinal cross-sectional view explaining the structure of a 1st heater, a 2nd heater, and a 3rd heater. It is explanatory drawing explaining the mode of the magnetic flux and eddy current which generate | occur | produce by the effect | action of a 1st heater, a 2nd heater, or a 3rd heater. It is a schematic plan view which shows the positional relationship of each core of a 1st heater, a 2nd heater, and a 3rd heater. It is a schematic plan view which shows the position where temperature is detected by the 1st temperature detector, the 2nd temperature detector, and the 3rd temperature detector. It is explanatory drawing explaining the calculating method in a control apparatus. In the case of heating only by a single heater and movable (alpha = 1) the core of the crude bar, NoboriAtsushiryou ΔT C _{(α = 1) 'and} the distance X given to the central portion P _{C 1} is a graph showing a relationship with ₁ . It is a top view explaining a mode that it heats only with one heater which made the core movable with respect to the coarse bar. In the case of heating only by a single heater and movable (alpha = 1) the core of the crude bar, NoboriAtsushiryou ΔT C _{(α = 1) 'and} the distance X given to the central portion P _C relationship between _1, and is a graph showing the relationship between the Atsushi Nobori amount given the distance X ₁ with respect to the lateral portion P _R. In the case of heating in two sets of heater and movable (alpha = 1) the core of the crude bar, temperature given to heating amount given to the central portion P _C and the side portions P _R it is a graph showing the relation between the temperature rise amount difference Delta] E R and _{(α = 1) 'and} distance X ₂ between the temperature amount. It is a top view explaining a mode that it heats with two heaters ((alpha) = 1) which made the core movable with respect to a rough bar. It is a perspective view showing a state in which a predetermined position h _k is moved in a portion opposed to the core of the first heater. It is a perspective view showing a state in which a predetermined position h _k is moved in a portion opposed to the core of the second heater. It is a perspective view showing a state in which a predetermined position h _k is moved to a portion facing the core of the third heater. Is a graph relating to the heating method according to another embodiment, in the case of heating in two sets of heater and movable core against crude bar (alpha = 1), the temperature given to the central portion P _C temperature the amount ΔT _{C (α = 1)} 'and the relationship between the distance _{X 2, ΔT RE (α =} 1)' relationship between the distance _{X 2,} heated amount difference ΔE _{R (α = 1)} 'and the intervals _{X 2} It is the graph which showed this relationship. 6 is a table showing an example of constants K1, K2, K3, K4, K5, and K6 used in relational expressions (1) ^* and (2) ^* in Experiment 1 of the example. In Experiment 1 of Example, the temperature distribution in the longitudinal direction of the central portion P _C before soaking, the temperature distribution in the length direction of the side portion P _R, the temperature distribution in the length direction of the side portions P _L measurements It is a graph which shows the result. In Experiment 1 of Example, the temperature distribution in the longitudinal direction of the central portion P _C after soaking, the temperature distribution in the length direction of the side portion P _R, the temperature distribution in the length direction of the side portions P _L measurements It is a graph which shows the result. It is the table | surface which showed an example of constant K1, K2, K3, K4, K51, K52, K6 used by relational expression (1), (2), (3) in Experiment 2 of an Example.

Explanation of symbols

C Center part D1 Movement direction D2 Width direction H Coarse bar (slab, steel plate)
_{h (h 1, h 2,} ··· h k ···) predetermined position in the length direction P _C central P _{R, P L} side sections X _{R, X L} interval 1 hot rolling mill 10 heating furnace 11 Rough rolling mill 12 First cutting machine 13 Soaking part 15 Edge heater 16 Finishing mill group 18 Transport rolls 21, 22, 23 Temperature detector 25 Controller 31, 32, 33 Heater 41, 42 Core

Claims (8)

A method of heating a steel material with a plurality of heaters before finish rolling in a hot rolling process,
While moving the steel material along the length direction, the steel material is heated in this order by the first heater, the second heater, and the third heater,
The first heater, the second heater, and the third heater are transverse type induction heating devices,
Any one of the first heater, the second heater, and the third heater is a heater for a central portion that is disposed so that the core faces the central portion in the width direction of the steel material. One is a first side heater arranged so that the core faces one edge in the width direction of the steel material, and one of the other is the other edge in the width direction of the steel material. A second side heater arranged to face the side,
A first gap formed between the core of the first side heater and the central portion of the steel material; and a gap between the core of the second side heater and the central portion of the steel material. Each second interval that is formed can be varied,
Over the length direction of the steel, the target value of NoboriAtsushiryou [Delta] T _C provided by the heat treatment on the central portion of the steel, first located between the central portion and one edge of the steel target value of the temperature rise amount difference Delta] E _R of temperature increase amount given by the heat treatment on the side portion and the temperature Yutakaryou [Delta] T _C, and, located between the central portion and the other edge of the steel based on the target value of the temperature rise amount difference Delta] E _L between the second said temperature Yutakaryou [Delta] T _C and heating amount given by the heat treatment on the side portions of the target value of the output of the heater for the center portion, Obtaining a target value of the output of the first side heater, a target value of the output of the second side heater, a target value of the first interval, and a target value of the second interval;
The output of the central heater when the core of the central heater faces a predetermined position in the length direction of the steel material, when the core of the first side heater faces the predetermined position The output of the first side heater and the output of the second side heater when the core of the second side heater faces the predetermined position are made the same, A method for heating steel material, characterized by adjusting one interval and the second interval. Wherein the temperature Yutakaryou [Delta] T _C, and the same output from each other, said the first interval using a first relational expression indicating a relationship between the second interval, the same output target value with each other , To determine a target value for the first interval and a target value for the second interval;
Wherein the first relationship is the temperature Yutakaryou [Delta] T _C, the temperature increase amount given to the central portion of the steel material in the predetermined position by the central heater, said first side heater The amount of temperature increase given to the central part of the steel material at the predetermined position by the second side heater and the amount of temperature increase given to the central part of the steel material at the predetermined position by the second side heater Represented by a linearly coupled expression,
The amount of temperature rise given to the central portion of the steel material at the predetermined position by the first side heater is expressed using a second-order polynomial with the first interval as a variable,
The temperature rise given to the central part of the steel material at the predetermined position by the second side heater is expressed using a second-order polynomial with the second interval as a variable. The method for heating a steel material according to claim 1. Using the second relational expression representing the relationship between the temperature rise difference ΔE _R , the same output, the first interval, and the second interval, the same output target A value, a target value for the first interval, and a target value for the second interval;
In the second relational expression, the temperature rise difference ΔE _R is calculated based on the temperature rise amount given to the first side portion at the predetermined position by the heating by the center heater and the center portion. By the heating amount difference from the heating amount given to the central portion of the steel material at the predetermined position by the heating by the heater, and by the heating of the first side heater and the second side heater The center of the steel material at the predetermined position by the heating amount given to the first side portion at the predetermined position and the heating of the first side heater and the second side heater. The difference in temperature rise from the temperature rise given to the part is expressed by a linearly coupled equation.
A heating amount applied to the first side portion at the predetermined position by heating of the first side heater and the second side heater, the first side heater, and The difference in temperature rise from the temperature rise given to the central portion of the steel material at the predetermined position by the heating of the second side heater is variable for the first interval and the second interval. The method for heating a steel material according to claim 1 or 2, characterized by using a first order polynomial. Wherein a temperature increasing amount difference Delta] E _L, and the same output from each other, said the first interval, using a third relational expression indicating a relationship between the second interval, the target of the mutually identical output A value, a target value for the first interval, and a target value for the second interval;
The third relational expression, the Atsushi Nobori amount difference Delta] E _L, said second side for the central portion and the Atsushi Nobori amount given to portions in the predetermined position by heating by the heater for the center portion By the heating amount difference from the heating amount given to the central portion of the steel material at the predetermined position by the heating by the heater, and by the heating of the first side heater and the second side heater The center of the steel material at the predetermined position by the heating amount given to the second side portion at the predetermined position and the heating of the first side heater and the second side heater. The difference in temperature rise from the temperature rise given to the part is expressed by a linearly coupled equation.
A heating amount given to the second side portion at the predetermined position by heating of the first side heater and the second side heater, the first side heater, The difference in temperature rise from the temperature rise given to the central portion of the steel material at the predetermined position by the heating of the second side heater is variable for the first interval and the second interval. The method for heating a steel material according to any one of claims 1 to 3, wherein the heating method is expressed using a first order polynomial. A target value of the output of the central heater, a target value of the output of the first side heater, a target value of the output of the second side heater, a target value of the first interval, and The target value of the second interval is
ΔT _C = (K1 + γ · K3 · _XL ² + γ · K3 · X _R ² + γ · K4) · α
ΔE _R = (K2 + γ · K51 · X _R + γ · K52 · X _L + γ · K6) · α
ΔE _L = (K2 + γ · K51 · X _L + γ · K52 · X _R + γ · K6) · α
(K1, K2, K3, K4, K51, K52, K6: coefficients depending on the width of the steel material,
γ: coefficient X _R relating to the state of the heating region by the first heater, the state of the heating region by the second heater, and the state of the heating region by the third heater: the first interval,
X _L : the second interval,
α: the ratio of the output of the central heater to the maximum output of the central heater, the ratio of the output of the first side heater to the maximum output of the first side heater, and the first Ratio of the output of the second side heater to the maximum output of the second side heater)
It calculates | requires using, The heating method of the steel materials in any one of Claims 1-4 characterized by the above-mentioned. The method for heating a steel material according to any one of claims 1 to 5, wherein the target value of the first interval and the target value of the second interval are the same. A target value of the output of the central heater, a target value of the output of the first side heater, a target value of the output of the second side heater, a target value of the first interval, and A target value for the second interval is calculated by explicit method;
The method for heating a steel material according to any one of claims 1 to 6, wherein the central heater, the first side heater, and the second side heater are controlled at a constant cycle. . Before performing the heat treatment, the temperature T _C of the central part of the steel material, the temperature T _{RE of} the first side part, and the temperature T _LE of the second side part are detected,
The temperature _{T C,} and, from the target temperature _{T t} by the heat treatment, obtains a target value of the temperature Yutakaryou [Delta] T _C,
From the temperatures T _C and T _RE , a target value of the temperature increase difference ΔE _R is obtained,
The temperature T _C, from T _LE, and obtains a target value of the Atsushi Nobori amount difference Delta] E _L, the heating method of the steel according to any one of claims 1 to 7.

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