JPH0688043B2 - Slab width reduction method - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a method for reducing the width dimension of a slab, which is a material for hot rolling.

[Background of the Invention]

In recent years, most of slab materials for hot rolling have been produced by a continuous casting machine (hereinafter referred to as a continuous casting machine). However, the current continuous casting machine forms the slab material through the mold and cannot change the slab width rapidly, so
There is a drawback that slabs of various widths cannot be produced efficiently. Therefore, in order to efficiently produce slabs with various strip widths, it is considered to produce slabs with a constant strip width in a continuous casting machine and reduce the slab to a strip width required in a hot rolling line. Therefore, in the hot rolling line,
There is a demand for a technology that enables a wide range of plate width adjustment.

As one of the techniques for reducing the slab width, there is a vertical rolling mill. This is because the pair of rolls rolls down the width direction of the slab, and therefore has the following drawbacks.

(1) A raised portion having a thickness called a dog bone is formed near both ends in the width direction of the slab, and when horizontal rolling is performed in a subsequent horizontal rolling mill, the width return amount becomes large.

(2) The buckling phenomenon in the plate width direction is likely to occur in the slab, and the width cannot be significantly reduced by one pass, and the width needs to be gradually reduced over several passes.

(3) A crop portion called a "fit tail" is formed at the front end portion and the rear end portion of the slab in the longitudinal direction, which deteriorates the yield.

Another method for reducing the slab width is disclosed in Japanese Patent Laid-Open No. 56-68504.
There is one described in the publication. This method is to reduce the slab width by a vertical rolling mill after prepress-forming the leading end portion and the trailing end portion of the slab with a pair of press tools having a tapered portion or a rounded portion and a linear portion. Is. However, this method can prevent the above-mentioned fishtail of (3), but cannot compensate for the other drawbacks of (1) and (2).

Therefore, the inventors have used a pair of press tools having a pressing surface parallel to the side surface of the slab while continuously moving the slab in the longitudinal direction to periodically compress the slab in the width direction to reduce the width dimension. We devised a press-type slab width reduction method to achieve this (Japanese Patent Application No. 57-209367). According to this method, the raised portion of the thickness of the dock bone is closer to the center in the width direction, and the amount thereof is reduced. Moreover, the slab width can be significantly reduced. However, also in this method, a tongue-shaped clip portion called a tongue is formed at the front end portion and the rear end portion of the slab. Therefore, the inventors applied for Japanese Patent Application No. Sho 58-201502 in order to compensate for this drawback, and include a surface parallel to the side surface of the slab and a rounded portion that is inclined outwardly toward the slab entry side with respect to this surface. It was confirmed by a test that a pair of pressing surfaces, which are opposed to each other, vibrate to press the side surface of the slab by vibrating it and devise a method to reduce the width, and it is possible to significantly reduce the slab front and rear end clips. . However, when the inventors reduce the width over the entire length of the slab by this method, it becomes intermittent because the feeding of the slab must be performed during the opening operation of the pair of pressing tools facing each other. If the shape, especially the length of the surface parallel to the slab side of the press tool is short,
It has been found that it is difficult to secure a predetermined width accuracy because unevenness occurs on the side surface of the slab after the width is reduced.

[Object of the Invention]

It is an object of the present invention to provide a slab width reducing method capable of improving the width dimension accuracy when the slab width is reduced by periodically pressing the slab using a pair of press tools.

[Outline of Invention]

The present invention relates to a slab conveyed in the longitudinal direction, a pair of press tools provided with a parallel portion parallel to the slab side surface and an inclined portion inclined toward the slab entry side in a direction away from the side surface. Is arranged on both sides in the width direction of the slab, and when the slab is cyclically pressed in the width direction by this press tool to perform width reduction processing, the length of the slab in each pressing step of pressing against the slab. By setting the amount of movement in the direction to be less than 1/2 of the parallel length of the press tool, each portion of the side surface of the slab is pressed at least twice and the width is sequentially reduced over the entire length of the slab. The slab is processed so that the width dimension accuracy of the slab can be improved.

Example of Invention

A preferred embodiment of the slab width reducing method according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 shows a pair of press tools each having a parallel portion parallel to the side surface of the slab and a drawing portion whose slab entry side is gradually separated from the slab. 1 is a schematic diagram showing a method of reducing the slab width by periodically pressing the slab side surface with a pair of press tools while intermittently conveying the slab material. As shown in FIG. 2 (a), the slab 10 before width reduction is intermittently conveyed rightward in FIG. 2 as indicated by an arrow 12, and the side surface is pressed by the pair of press tools 14 and 16, and the width is reduced. After Slab 18
Becomes The slab width of the slab 10 before width reduction is W ₀ , the slab width of the slab 18 after width reduction is W _1, and the width reduction amount is ΔW.
Is. Further, a portion of the press tools 14, 16 parallel to the slab material, that is, the length of the parallel portion is _S , the opening angle of the narrowed portion is θ, the amplitude of the pair of press tools 14 and 16 is 2a, and the frequency of vibration is Let L be the amount of movement (feed amount) of the slab in the longitudinal direction.

Now, as shown in FIG. 2A, when the width reduction amount ΔW / 2 on one side obtained by being pressed by the press tools 14, 16 is larger than the amplitude a of the press tool on one side, the press tools 14, 16
The amount of advance of the slab when the slab is in an open state, that is, the feed amount L of the slab can advance until the narrowed and inclined portion of the slab contacts the open tools 14 and 16, L ≦ a / tan θ can be set as (1). Then, when the slab advances by L, the A ₀ point advances to the A ₁ point, and if the length l _S of the straight part (parallel part) of the press tools 14, 16 is l _S <L ...... (2), As shown in Fig. 2 (b), point A ₁ advances to the outside of the press tool, and the non-width adjustment portion B is generated. Therefore, the parallel part length l _S of the press tool must be l _S > L (3).

Therefore, the inventors set a model (test material; hot steel dimension 22 mm thickness x 150 mm width) of about 1/10 of the actual size as l _S > L + α (0 <α <L) (4) As a result of fabrication and experimentation, even if the parallel part length l _S satisfies the formula (4), the width is reduced as shown in FIG. 3, and then the side surface of the slab is uneven along the longitudinal direction. I discovered a phenomenon that occurs. Therefore, the inventors Also, when the experiment was carried out by changing the value of l _S while keeping the feed amount L once and constant, the results shown in FIG. 4 were obtained. That is, when the feed amount L is 32 mm, when the opening angle θ of the press tool is 12 degrees and the parallel part length l _S = 45 mm, the processing history received at the parallel part at the point A ₀ is once and l _S = 90 mm. In the case of l _S = 110 mm, the number of times is three, and the more the processing history is, the better the width accuracy is. However, when the processing history is two or more times, a large difference in width accuracy is not recognized, and a value of this level can be sufficiently corrected by the width rolling machine in the finishing rolling facility in the post process.

The above explanation is as shown in FIG. The case has been explained, but as shown in FIG. The same is true in the case of.

On the other hand, the inventors obtained the result of FIG. 5 when the relationship between the number of times of processing in the width reducing method and the temperature of the slab material was obtained by calculation and confirmed by actual measurement. That is, 1150
When the slab material at 0 ° C. is processed by the press tools 14 and 16, the temperature decreases due to heat conduction at the contact portion with the press tools. Then, it has become clear that the more the number of times of contact, that is, the number of times of processing, is, the more the temperature decreases remarkably, and the number of times of processing is preferably smaller from the viewpoint of preventing the temperature decrease of the slab material. That is, if the temperature of the slab material is remarkably lowered, the rolling energy in the subsequent step causes an increase in processing energy due to an increase in deformation resistance, which is disadvantageous in terms of cost, so the temperature of the slab material is not reduced as much as possible. It is desirable to do so.

From the above, it is necessary to receive the processing history at least twice in the parallel portion of the press tool in terms of the width dimension accuracy, but the processing history should be three times or less from the viewpoint of preventing the slab material temperature from decreasing. It became clear that it was desirable.

FIG. 6 shows a press machine for carrying out the slab width reducing method described above. In Fig. 6, slab 10 before width reduction
Is sent to the pressing device 22 by the pinch roller 20, is pressed in the width direction by the press tools 14 and 16, and is connected to the slab 18 after the width is reduced and pulled out by the pinch roller 24.
The press tools 14 and 16 each have a dovetail groove 28 on the tool support 26.
Has been inserted into. The tool support base 26 is connected to the piston 32 of the cylinder 30 so that it can move inside the housing 34 at right angles to the traveling direction of the slab. Also,
The press tools 14 and 16 are provided with engaging portions 36 adjacent to the tool supporting base 26 on the inlet side and the outlet side of the slab, and the engaging hooks 36 are engaged with a fixed hook 38 having a crank shape. I am fit. The fixed hook 38 is pivotally supported by a bracket 42 provided on the tool support 26 at an intermediate portion via a pin 40 and at a rear end by a piston 48 of a cylinder 46 via a pin 44. . In the cylinder 46, the fixed hook 38 and the engaging portion 36 can be engaged and disengaged by introducing the hydraulic oil into the oil holes 50 and 52.

The cylinder 30 is provided with a position detector 54 and oil holes 56 and 58. Pipes 62, 64 communicating with the servo valve 60 are connected to the oil holes 56, 58. The servo valve 60 is connected to the oil tank 66 and the pump 68, and is operated by a command device 72 via a controller 70 that receives a detection signal from the position detector 54.

The cylinder 30 is fixed to a guide 76 connected to the screw 74, and moves in the housing 34 integrally with the guide 76 as the screw 74 operates. The screw 74 penetrates a casing 78 provided in the housing 34, and a screw portion 80 is screwed with a worm wheel 82 provided in the casing 78. Then, the worm wheel 82 rotates around the screw 74 as the worm 84 rotates, and moves the screw 74 at right angles to the traveling direction of the slab.

The pinch rollers 20, 24 arranged in front of and behind the housing 34 are
The bearings 86 and 88 are rotatably supported, respectively, and are connected to drive motors 94 and 96 via speed reducers 90 and 92, respectively. The rotation speeds n ₁ and n ₂ of the drive motors 94 and 96 are given by inputting command values of the command devices 98 and 100 to a motor drive power source (not shown) via the controllers 102 and 104. Further, the drive motors 94, 96 are respectively equipped with tachometers 106, 108, the actual number of rotations of the pinch rollers 20, 24 is detected and fed back to the controllers 102, 104, and compared with the command values of the command devices 98, 100, always. The correct rotation speeds n ₁ and n ₂ are set.

As shown in FIG. 7, the press tools 14 and 16 have parallel portions 110 and 112 and narrowed portions 114 and 116 on the slab side (inside), respectively. The parallel portions 110 and 112 are formed from the substantial center of the press tools 14 and 16 to the slab exit side, and the surfaces of the parallel portions 110 and 112 are parallel to the side surfaces of the slab. Further, the diaphragm units 114 and 116 are
The press tools 14 and 16 are formed so as to gradually narrow the slab width from the slab entrance end to the substantially center. This diaphragm
The inclination angle θ of 114 and 116 is preferably 6 to 20 degrees and may be a curved surface.

The reduction of the slab width by the press device configured as described above is performed as follows. The pinch rollers 20 and 24 are rotationally driven by drive motors 94 and 96 via speed reducers 90 and 92, and jointly convey the slab material to the right in Fig. 6 intermittently. On the other hand, the command device 72 opens and closes the servo valve 60 at a predetermined cycle via the controller 70. Then, the pump 68 operates the hydraulic oil in the oil tank 66 by a servo valve.
According to the open / closed state of 60, it is pressure-fed to the cylinder 30 through the pipe 62 or the pipe 64. That is, when the hydraulic oil is introduced into the oil hole 56 through the pipe 62 by the pump 68, the piston 32 moves to the cylinder 30.
Then, the press tools 14 and 16 are opened and the hydraulic oil in the cylinder 30 is transferred from the oil hole 58 through the pipe 64 to the oil tank 66.
Return to. Further, when the hydraulic oil is introduced into the cylinder 30 from the oil hole 58 through the pipe 64, the piston 32 is pushed out of the cylinder 30, and the press tools 14 and 16 are brought close to each other to reduce the width of the slab 10 before width reduction. Press in the direction to reduce the width to form the slab 18.

A single feed amount L for conveying these slab materials and a press tool
The relationship between the length l _S of the parallel portions 110 and 112 of 14, 16 and the rotational speeds n ₁ and n ₂ of the pinch rollers 20 and 24 is as follows. As shown in FIG. 1, the one-sided amplitude a of the press tools 14 and 16, the closing operation time t ₁ second, the opening operation time t ₂ seconds, the one-sided width reduction amount of the slab Is determined according to the width reduction schedule. Then, during the opening operation of the press tools 14 and 16 (t ₂ seconds), the slab material is transported by the feed amount L in the longitudinal direction by the pinch rollers 20 and 24, and during the closing operation of the press tools 14 and 16 (t ₁ second). ), The width is reduced by ΔW. Number of rotations of the pinch roller 20 in this case
The n ₁ and the rotation speed n ₂ of the pinch roller 24 are determined as follows.

The diameter of the pinch roller 20 is D ₁ and the diameter of the pinch roller 24 is D ₂
Then, L = πD ₁ n ₁ t ₂ (5) or L = πD ₂ n ₂ t ₂ (6) On the other hand, as described above, in order to obtain good width accuracy of the slab, Must be pressed more than once in the parallel portions 110, 112 of the press tools 14, 16, so that L <l _S / 2 (7). Further, the feed amount L is preferably set to l _S / 3 <L <l _S / 2 (8) in consideration of the prevention of temperature decrease of the slab material. Therefore, (5), (6),
From the formula (8), the rotation speed n ₁ of the pinch roller 20 and the pinch roller
The rotation speed n _{2 of} 24 is as follows.

Therefore, by inputting the values of n ₁ and n ₂ to the commanders 98 and 100, it is possible to obtain the feed amount L required to obtain good width accuracy. The above embodiment has described the method of giving the limit value of the feed amount L of the slab material required to obtain good width accuracy based on the length l _S of the parallel portions 110, 112 of the press tools 14, 16. As will be described below, the length l _S of the parallel part of the press tool can be obtained from the limit of the production amount, that is, the feed amount L of the slab required to obtain the determined production amount.

Now, assuming that the feed rate of the slab material required to obtain a certain production amount is v _P , the slab material moves only during the opening operation of the press tools 14 and 16, so v _P ≤L / t ₂ …… (11 ) Must. Therefore, from equations (7) and (11), l _S > 2v _P t ₂ (12) is obtained, and the lower limit of the length l _S of the parallel part of the press tools 14, 16 is determined. . When the plate width of the slab, which is a hot-rolled material, is reduced by the relationship between the feed amount L and the length l _S of the parallel portion, the yield is improved by reducing the crop portion at the rear end of the slab, and the horizontal level is improved. In addition to reducing the width return amount during rolling, good width accuracy can be secured over the entire length of the slab.

〔The invention's effect〕

As described above, according to the present invention, the width dimension accuracy of the slab can be improved when the width direction of the slab is periodically pressed to reduce the slab width.

[Brief description of drawings]

FIG. 1 is an explanatory view of an embodiment of a slab width reducing method according to the present invention, and FIGS. 2 (a) to (c) are views showing the relationship between the feed amount of the slab and the length of the parallel portion of the press tool, FIG. Fig. 3 is a schematic diagram showing the variation in the width dimension of the slab, Fig. 4 is a characteristic diagram of the width accuracy with respect to the parallel portion length of the press tool when the feed amount of the slab is constant, and Fig. 5 shows the press tool and the slab. Fig. 6 is a characteristic view showing the temperature change of the slab with the number of contacts of Fig. 6, Fig. 6 is a plan view showing a cross section of a part of a press device for implementing the slab width reducing method according to the present invention, and Fig. 7 is an embodiment of a press tool FIG. 10 …… Slab before width reduction, 14,16 …… Press tool, 18 ……
After width reduction Slab, 30 …… Cylinder, 32 …… Piston, 11
0,112 …… Parallel part, 114,116 …… Throttle part, L …… Feed amount,
l _S …… Length of parallel part.

Claims (2)

[Claims] 1. A slab that is conveyed in the longitudinal direction, is disposed on both sides in the width direction of the slab, and is parallel to a side surface of the slab and a direction that separates from the side surface toward the slab entry side. In a slab width reducing method of cyclically pressing and reducing the slab in a width direction by a pair of press tools having an inclined slant portion, the length of the slab in each pressing step of pressing against the slab. A slab width reduction method characterized in that the amount of movement in the direction is set to be smaller than 1/2 of the length of the parallel part of the press tool, and the width reduction process is sequentially performed over the entire length of the slab. 2. The amount of movement of the slab in the longitudinal direction of the slab per pressing process is less than 1/2 and more than 1/3 of the length of the parallel portion of the press tool. The slab width reducing method according to claim 1.