JPH0636935B2 - Hot seat bar heating device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a hot sheet bar heating apparatus, and more particularly to a hot sheet bar heating apparatus for heating and rolling a sheet bar.

[Conventional technology]

Explaining the rolling method of the hot sheet bar in the steel strip rolling that has been conventionally performed, in the meantime, in the hot rolling, the heated slab having a thickness of 120 to 300 mm is made to have a thickness of 15 to 60 mm by a rough rolling mill. Rolled into a sheet bar
This is further rolled by a finishing mill to the required product thickness.

Here, as shown in FIG. 7, the hot sheet bar rolled by the rough rolling mill 1 is transferred to the crop shear 4 by the transport table roller 5, and the tip portion of the sheet bar is sheared. Then, the sheet bar 3 is transferred to a high-pressure jet type scaling device 11 having a nozzle 8 for removing the surface scale, and then the finish bar 2 is used to finish-roll the sheet bar 3.

During this processing step from rough rolling to finish rolling, part of the heat retained by the hot sheet bar is dissipated into the atmosphere. Since the amount of heat radiated increases in proportion to the time required for processing, there is a difference in the amount of heat radiated into the atmosphere between the widthwise side end and the center of the hot sheet bar, and the temperature of the hot sheet bar is The temperature at the widthwise side end becomes lower than that at the widthwise central part. For this reason,
There is a problem in that the quality of the finished rolled product deteriorates due to a material defect at the side end portion.

Therefore, in order to solve such a problem, as shown in FIG. 7, an edge heater 10 which is a hot seat bar heating device for compensating for a temperature drop at both end portions of the seat bar 3 is installed. However, it has been proposed to locally raise the temperature of the edge portion of the hot sheet bar to compensate for the temperature drop of the edge portion (for example, "Iron and Steel," No. 72 of 1972 (1986),
Pp. 177-178).

In this edge heater, as shown in FIG. 7, a plurality of pairs of upper and lower induction heating coils 10A are installed on both edge portions of the hot seat bar 3. The pair of upper and lower induction heating coils 10A has a mechanism that follows the position corresponding to the edge portion of the hot sheet bar 3 even if the width of the hot sheet bar 3 changes.

As described above, in the above-mentioned conventional example, the edge heater is used in order to prevent occurrence of uneven temperature distribution in the width direction of the hot sheet bar 3 between the rough rolling mill 1 and the finish rolling mill 2. .

[Problems to be Solved by the Invention]

However, as a result of diligent studies by the present inventors, heat dissipation from the seat bar occurs not only in the width direction end part but also in the longitudinal direction end part (front end / rear end) of the seat bar, resulting in various problems. I found that.

That is, the first of the problems is a defective material at the front and rear ends of the seat bar. The finish rolling temperature is usually set so that the rolling is completed at the Ar ₃ transformation point or higher. However, in the above-described conventional sheet bar rolling method, the local temperature drop portions at the front and rear ends of the sheet bar become Ar ₃ points or less, and abnormal growth of crystal grains, so-called grain loss occurs. As a result, not only the workability of the product is lowered, but also cold rolling property, which is often performed continuously in recent years, is deteriorated.

The second of the above problems is roll flaws. In the case of a steel type sheet bar having a high deformation resistance, when the temperature drop occurs, the roll is plastically deformed when the tip of the sheet bar is caught in the finish rolling mill. For this reason, roll flaws are transferred to the surface of the product, which may cause surface defects, resulting in defective products. Therefore, it is necessary to suddenly replace the rolls, which reduces the operating rate.

In order to prevent the above problem, the longitudinal end portion of the sheet bar, that is, the front and rear ends must be cut off, but this has a problem that the yield of the product is reduced.

Therefore, in order to solve such a problem, the present invention improves the yield by preventing the material defect of the end portion in the longitudinal direction of the seat bar, and prevents the occurrence of roll flaws to improve the operation rate. It is an object of the present invention to provide a heating device for a hot seat bar.

[Means for Solving the Problems]

In order to achieve the above object, the heating device of the hot sheet bar according to the present invention, by heating the width direction side end of the hot sheet bar conveyed from the hot rough rolling mill on the entry side of the finishing rolling mill. In the hot sheet bar heating device, the sheet bar end detecting means for detecting that the longitudinal end portion of the sheet bar has reached the heating region of the heating device, and the end portion in the longitudinal direction of the sheet bar by the detecting means. When the arrival of the sheet bar is detected, the sheet bar conveyance speed control means for stopping or decelerating the conveyance of the sheet bar for a predetermined time, and the heating device is moved in the sheet bar width direction during the stop or deceleration period of the sheet bar conveyance. And a heating device movement control means.

[Action]

According to the above invention, the sheet bar end portion detecting means detects the sheet bar longitudinal direction end portion, and the sheet bar conveying speed control means detects the arrival of the sheet bar longitudinal direction end portion of the sheet bar. The conveyance is stopped or decelerated for a predetermined time, and in the heating device movement control means, as a result of heating by moving the sheet bar in the width direction, not only the edge portion of the sheet bar but also the longitudinal end portion is heated before finish rolling,
Since the temperature drop in this portion can be compensated, abnormal growth of crystal grains can be prevented, and as a result, the material defect does not occur at the longitudinal end portion of the sheet bar. Therefore, as compared with the conventional hot sheet bar rolling method, it is possible to improve workability and cold rollability in finish rolling while improving yield.

Further, as a result of preventing the material defect, the roll is not plastically deformed when the tip of the steel type sheet bar having a high deformation resistance is bitten by the roll, so that the roll can be prevented from being flawed.

〔Example〕

Next, embodiments according to the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a block diagram of an embodiment of the device of the present invention. Instead of the edge heater 10 shown in FIG.
An induction heating device 6 is provided for heating both the width direction side end portion (edge portion) and the longitudinal direction end portion (front end / rear end) thereof. As shown in the side view of FIG. 1 (a), the induction heating device 6 includes a pair of upper and lower induction heating coils 30A, 3A.
0B, the induction heating device 6 is further shown in FIG.
As shown in the plan view of (b), two units are provided in parallel with the width direction of the seat bar 3 (6A, 6B). The output of these induction heating coils can be controlled separately, and the moving position of the seat bar 3 in the width direction can be adjusted.

Next, FIG. 2 shows a block diagram of the above-mentioned FIG. The same parts as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted. FIG. 2 is a side view of the rolling equipment. To explain the configuration, a high frequency power supply 27 is connected to each of the induction heating coils of the induction heating device 6. Further, the induction heating coil has a coil drive circuit 2 for moving the induction heating device 6 in the width direction of the seat bar 3.
2 is connected. The coil drive circuit 22 and the high frequency power supply 27 are connected to the controller 21.

Provided on the upstream side of the induction heating device 6 are a front end detector 25 for detecting passage of the front end of the seat bar 3 and a temperature sensor 26 for detecting the temperature of the seat bar 3, and the front end detector 25 and the temperature sensor. 26 is connected to the controller 21.

Further, one of the conveying rollers 5 is connected to a measuring roll 23 for measuring the moving amount of the sheet bar 3, and one of the conveying rollers 5 is for detecting the moving speed of the sheet bar 3. Speed detector 24 is provided. The measuring roll 23 and the speed detector 24 are connected to the controller 21.

The controller 21 is composed of, for example, a microcomputer, and an interface (not shown)
A temperature setting circuit (not shown) is connected and a target temperature value to be raised by the induction heating device 6 can be set.

As shown in the side view of FIG. 3, the induction heating apparatus used in this embodiment has a pair of upper and lower induction heating coils 30A and 30A.
B, the upper induction heating coil 30A is fixed to the tip of the upper support arm 31A. A lower induction heating coil 30B is fixed to the tip of the lower support arm 31B. The pair of upper and lower support arms 31A and 31B are
It is swingably fixed to the left end of the support 38 of the carriage 32. An opening / closing cylinder 35 is installed on the right side of the upper support arm 31A.
An opening / closing cylinder 36 is also installed at the right end of the. 33 is a rail formed at right angles to the rolling line, and 34 is a wheel for moving the carriage 32 along the rail. In addition, 40 is a bearing of the conveyance roller 5.

An electric motor for rotating the wheels 34 is housed in the carriage 32, and the electric motor can be controlled based on an output signal from the drive circuit 22.

Support arms 31A and 31B of the induction heating apparatus shown in FIG.
Is an induction heating coil 30A, 30B provided at the left end
Is formed to have a sufficient length to move the sheet bar 3 to the center of the seat bar 3. This induction heating device uses rail 3
The sheet 3 can be moved at a right angle in the conveying direction of the sheet bar 3. That is, when the induction heating coils 30A and 30B are moved to the widthwise center of the seat bar 3,
By running on the rail 33 toward the seat bar, it is possible to move these induction heating coils toward the center portion in the width direction of the seat bar. If the seat bar 3 is warped, the induction heating coil may be destroyed. Therefore, by driving the opening / closing cylinders 35 and 36, the support arms 31A and 31B can swing around the support shaft 39. .

Next, the operation of the embodiment shown in FIG. 2 will be described based on the flowchart of FIG.

In FIG. 2, the sheet bar 3 is conveyed rightward in the drawing, and the tip of the sheet bar 3 has a tip detector 2.
When it reaches 5 (for example, an infrared sensor), the detector 25 detects the infrared rays of the seat bar 3 to control the signal of the theoretical value (1) indicating that the tip of the seat bar 3 has arrived. 21 is output. That is, in the step of FIG. 4, it is determined whether or not the signal S ₁ output from the detector 25 to the controller 21 has the theoretical value (1).

If it is determined in the above step that the signal S ₁ = “1”, the process proceeds to step. In this step, the temperature sensor 26 detects the temperature of the tip portion of the seat bar 3 and sends the detected signal to the controller 21. An infrared thermometer, for example, can be used as the temperature sensor. The controller 21 reads the seat bar tip temperature T _K according to a signal from the temperature sensor 26 based on a storage table stored in advance in a storage device.
Further, when the controller 21 detects the tip of the seat bar 3 by the signal S ₁ from the detector 25, the warp of the tip of the hot seat bar 3 does not damage the pair of upper and lower induction heating coils 30A and 30B. In this way, the induction heating coils 30A and 30B are moved in the direction in which they are separated from each other.

Then, the process proceeds to step. The speed detector 24 detects the detection signal composed of the number of pulses according to the rotation speed of the transport roller 5.
Outputs S _3, the controller 21 reads the detection signal S _3, calculates the conveying speed of the sheet bar 3 to count the number of pulses.

Then move to step and measure roll 23
Outputs to the controller 21 a detection signal S ₂ consisting of a pulse signal corresponding to the carry amount of the sheet bar 3. The controller 21 calculates the amount of movement of the sheet bar from the time when the leading edge detector 25 detects the leading edge of the sheet bar by counting the number of pulses. Therefore, by storing the distance from the tip detector 25 to the induction heating coil 6 in the storage device of the controller 21 in advance, the time when the tip of the seat bar 3 reaches the induction heating coil 6 is detected. can do.

Next, when it is determined that the leading end of the sheet bar 3 has reached the induction heating coil 6 in the above step, the controller 21 outputs a signal to a conveyance control device for the sheet bar 3 (not shown), The tip of 3 is stopped between the induction heating coils 30A and 30B for a predetermined time.

Next, the process proceeds to step, and the target temperature preset in the controller 21 is read by the setter. The target temperature referred to here is the target temperature at the tip of the seat bar 3 after being heated by the coil 6.

Then, the process proceeds to step. In the controller 21, the tip temperature of the sheet bar read in the above step
The difference between T _K and the target temperature T _M read in the above step is calculated.

Next, the process proceeds to step, and from the temperature difference (T _M −T _K ) in the above step and the thickness of the seat bar and the material of the seat bar 3 which are preset in the controller 21,
The output of the high frequency power supply 27 that determines the output of the induction heating coil 6 is controlled based on a storage table stored in advance in the storage device of the controller 21. That is, the controller 2
In No. 1, the output of the high frequency power supply 27 is controlled so that the temperature at the tip of the seat bar 3 detected by the temperature sensor 26 matches the target temperature according to the material and thickness of the seat bar 3 and further the transport speed. To do.

Then, the process proceeds to step. In step, the controller 21 outputs a control signal to the coil drive circuit 22,
Control is performed to move the induction heating coil 6 in the width direction of the seat bar 3. At this time, as shown in FIG. 5 (A), the induction heating coils 6A and 6B existing on both side ends of the seat bar 3 are connected to the induction heating coil 6A as shown in FIG. 5 (B). The heating coil 6B is approached to its approach limit value. As for the amount of movement of the induction heating coil in the seat bar width direction in FIG. 3, the induction heating device is equipped with a potentiometer that outputs a voltage signal according to the amount of movement of the carriage 32. The output signal from this potentiometer and the coil driving from the controller 21 are used. By calculating the difference from the control signal output to the circuit 22 and outputting the control signal from the coil driving circuit 22 to the induction heating coil 6 so that this difference becomes zero, the induction heating device 6 in the seat bar width direction. The amount of movement can be determined.

Then, as shown in FIG. 5 (C), the induction heating coil 6A
After moving 6B and 6B together toward the right in the drawing, the induction heating coil 6B is further moved toward the left in the drawing, as shown in FIG. 5D. As a result, seat bar 3
Since the entire width direction of the tip end portion is heated by the induction heating coil 6, the temperature drop at the tip end portion can be compensated.

The induction heating coil 6 is for heating the seat bar 3 by generating an induced current. The capacity of the induction heating coil can be reduced as the expected warp amount (permissible amount) of the tip portion of the seat bar 3 is smaller. However, when the permissible value of the warp amount is increased, a large capacity is required. It is necessary to use the induction heating coil. Further, as in the present embodiment, when induction heating is performed while the seat bar 3 is running instead of stopping the seat bar 3 to perform induction heating, a large capacity induction heating device is required.

Next, as shown in FIG. 5 (D), the induction heating coil 6 is moved to the edge portion of the seat bar from the central portion in the width direction of the seat bar.

Next, the process shifts to step, and it is determined whether or not the sheet bar conveyance stop period has reached a predetermined time. If it is determined that the predetermined time has elapsed, that is, time up, the process proceeds to step.

In this step, the conveyance of the sheet bar is restarted, and as shown in FIG. 5 (D), the edge heating of the sheet bar is continuously performed by the induction heating coils 6A and 6B which are moved to both end portions in the width direction of the sheet bar. To do. After the tip of the hot seat bar 3 passes through the induction heating coil 6, the controller 21 outputs a control signal to the coil drive circuit 22 so as to narrow the space between the induction heating coils 30A and 30B. Thereby, the heating efficiency is significantly improved.

Next, the process proceeds to step, it is determined whether or not the control is ended, and if it is determined that the control is ended, the above operation is ended.

Although the heating of the tip portion of the seat bar 3 has been described in this embodiment, the heating of the rear end portion of the seat bar 3 can be performed in the same manner as the above-mentioned tip portion. At this time, it is necessary to detect the rear end portion of the seat bar 3. This is because the length of the seat bar 3 is preset in the controller 21 and the amount of movement of the seat bar 3 is determined by the measuring roll 23. Since it is constantly monitored, it is possible to easily heat the rear end portion of the seat bar 3.

According to the present embodiment described above, since the temperature at the tip portion of the seat bar 3 can be accurately raised to the target temperature, the temperature drop in the seat bar 3 can be compensated.
It is possible to prevent abnormal growth of crystal grains and prevent material defects at the longitudinal ends of the sheet bar.

In this embodiment, the induction heating coil 6 constitutes a heating device, and the operation of the tip detector 25 and the step constitutes a sheet bar edge detecting means.
The sheet bar transport speed control means is formed by the step operation, and the heating device movement control means is constituted by the coil drive circuit 22 and the step and step operation.

On the upstream side of the induction heating coil shown in FIG. 2, a pinch roller for correcting the warp of the tip portion of the sheet bar 3 can be provided. Since the warp of the tip of the sheet bar 3 is corrected and flattened by the pinch roller, the gap between the upper induction heating coil and the lower induction heating coil in the induction heating device 6 can be set to be small. it can. Therefore, it is possible to significantly reduce the capacity of these heating coils and reduce the equipment cost.
Further, it is not necessary to make the heating coil movable so as to move vertically toward the seat bar 3.

Next, specific examples will be described. FIG. 6 is a graph showing the amount of temperature drop at the longitudinal ends of the 1050 ° C. sheet bar roughly rolled by the hot rough rolling mill. The graphs of FIGS. 6 (A) and (C) show the amount of temperature drop at the tip of the seat bar, and FIG. 6 (B).
And (D) are graphs showing the amount of temperature drop at the rear end of the seat bar. Furthermore, FIGS. 6 (A) and (B)
The graph of (3) is a case where only the edge portion of the sheet bar is heated, and the graphs of (C) and (D) are based on the apparatus shown in FIG. 2 and both the edge portion and the front and rear end portions of the sheet bar are heated. It is a graph when it did. The sixth
In the figure, FET indicates the temperature on the entrance side of the finish rolling mill, and FD
T represents the temperature at the exit side of the finish rolling mill.

The sheet bar thickness used in this example is 35 mm,
The product thickness finished by the finish rolling mill is 2 mm.

Usually, when the temperature drop amount at the longitudinal end portion of the sheet bar exceeds 30 ° C., a defective material due to grain loss usually occurs in that portion. Therefore, as shown in FIG. 6 (A), a defective material region at the tip of the seat bar is close to 5 m (product conversion length, the same applies hereinafter). Also, the sixth
As shown in FIG. 3B, the defective material portion at the rear end of the seat bar extends up to 2 m. On the other hand, as shown in FIG. 6 (C), when the temperature of the tip of the sheet bar is increased by 40 ° C., the defective portion is reduced to within 2 m from the tip. Further, as shown in FIG. 6 (D), the material defect portion at the rear end of the seat bar is reduced to within 1 m. Therefore, in the general low carbon material having a longitudinal direction of 1000 m, by heating the longitudinal end portion of the seat bar by 40 ° C., in the conventional example in which the longitudinal end portion of the seat bar is not heated,
The front end was cut off by 5 m and the rear end was cut off by 2 m. By heating the front and rear ends of the sheet bar, the front end was cut down to 2 m and the rear end was cut down to 1 m. To do. As a result, seat bar 1
Since the cutting amount is reduced by 3 m at the leading end and by 1 m at the trailing end per 000 m, the yield improvement margin is 0.4%, which leads to a significant cost reduction.

Further, even when the sheet bar made of a steel type having high deformation resistance in which the front and rear ends of the sheet bar were heated at 40 ° C. as described above was caught in the finish rolling roll 60 times, the roll was not flawed. On the other hand, based on the conventional example in which the front and rear ends were not heated, a sheet bar made of a steel type having high deformation resistance was bitten into the finish rolling roll 10 times, and it was confirmed that the roll had a flaw. .

As can be seen from this specific example, the heating region at the end in the longitudinal direction of the sheet bar is about 200 mm at the tip.
It can be seen that it is only necessary to heat the width of the strong (sheet-bar-converted length) and to heat the width of about 100 mm at the rear end (sheet-bar-converted length). However, it does not prevent heating of the width more than this.

As described above, according to the present embodiment, it is possible to prevent the material defect at the end portion in the longitudinal direction of the seat bar, improve the yield, and prevent the roll from being flawed.

In this example, one induction heating device was used in combination for heating for heating the end portion in the longitudinal direction of the sheet bar and for edge heating.However, these functions are separated and heating for edge heating is performed. The device and the heating device for heating the longitudinal ends can be provided separately.

Further, although the heating device is installed in front of the crop shear in this embodiment, the present invention is not limited to this and can be installed after the crop shear.

Further, the number of induction heating devices installed is not limited to that of this embodiment, and a plurality of heating devices can be arranged.

Further, in the present embodiment, the arrival of the tip portion of the seat bar is detected by the infrared sensor, but the present invention is not limited to this, and other optical sensors can be used.

Further, in the present embodiment, the rear end of the seat bar is detected based on the distance tracking method by the microcomputer, but other optical sensors can be used to detect the passage of the rear end of the seat bar.

Further, in the present embodiment, both the front end and the rear end of the seat bar are heated, but from the viewpoint that it is necessary to prevent the occurrence of roll flaws and improve the yield to some extent, only the front end of the seat bar is heated. However, it is also possible not to heat the rear end.

Furthermore, although the induction heating is described in the present embodiment, the present invention is not limited to this, and the same purpose can be achieved by using other heating means.

Further, in this embodiment, the conveyance of the sheet bar is stopped,
Although the tip end portion of the sheet bar is heated, the present invention is not limited to this, and the tip end portion of the sheet bar may be heated by reducing the conveying speed of the sheet bar for a predetermined time.

〔The invention's effect〕

As described above, according to the heating device for a hot sheet bar according to the present invention, not only the edge portion of the hot sheet bar but also the longitudinal end portion is heated. As a result of prevention, it is possible to avoid the occurrence of material defects in such portions. Therefore, the area where the front and rear ends of the seat bar are cut off is greatly reduced, and as a result, the yield is improved. Further, in the case of a steel type sheet bar having high deformation resistance, the occurrence of roll flaws can be prevented, and as a result, sudden replacement of rolls can be avoided and the operating rate is improved.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a hot sheet bar rolling apparatus according to the present invention, FIG. 2 is a block configuration diagram of FIG. 1, and FIG. 3 is a side view showing the configuration of an induction heating device. FIG. 4 is a flow chart showing the operation of FIG. 2, FIG. 5 is a front view showing a method of moving the induction heating coil, and FIG. 6 is a relation between the sheet bar converted length or product converted length and the temperature drop amount. FIG. 7 is a side view showing the configuration of a conventional hot sheet bar rolling apparatus. In the figure, 1 is a hot rough rolling mill, 2 is a finish rolling mill, 3 is a sheet bar, 5 is a conveying roller, 6 is an induction heating device, 10 is an edge heater, 21 is a controller, 22 is a coil drive circuit, and 23 is Measuring roll, 24 is a speed detector,
Reference numeral 25 is a tip detector, 26 is a temperature sensor, and 27 is a high frequency power source.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Takashi Kawase 1 Kawasaki-cho, Chiba-shi, Chiba Inside Kawasaki Steel Co., Ltd. (72) Inventor Hideyuki Yuzawa 1 Kawasaki-cho, Chiba-shi Kawasaki Steel Co., Ltd. Chiba Steel In-house

Claims (1)

[Claims] 1. A heating device for a hot sheet bar, comprising heating the widthwise side end of the hot sheetbar on the entry side of the finishing mill, wherein the longitudinal end of the sheetbar is a heating region of the heating device. And a sheet bar conveying speed for stopping or decelerating the conveying of the sheet bar for a predetermined time when the arrival of the longitudinal end of the sheet bar is detected by the detecting means. A heating device for a hot sheet bar, comprising: a control device; and a heating device movement control device that moves the heating device in the width direction of the sheet bar during a stop or deceleration period of the conveyance of the sheet bar.