JPH026007A - Heater for hot sheet bar - Google Patents

Abstract

PURPOSE:To improve the yield of a sheet bar by detecting the arrival of the longitudinal end of the sheet bar at a heating region with a device for heating the transverse ends of the sheet bar and stopping or decelerating the transport of the sheet bar, then moving the heater in the transverse direction of the sheet bar. CONSTITUTION:The longitudinal end of the sheet bar is detected by a means for detecting the end of the sheet bar 3 and the transport of the sheet bar is stopped or decelerated for a prescribed period of time by a means of controlling the transport speed of the sheet bar. The induction heater 6 is moved in the transverse direction of the sheet bar by a means of moving the heater and the sheet bar is heated, as a result of which, the longitudinal ends of the sheet bar are heated as well prior to finish rolling. As a result, the generation of material defects in the longitudinal ends of the sheet bar is obviated. In addition, the plastic deformation of rolls does not arise at the time when the front end of the sheet bar of a steel kind having high deformation resistance is bitten into the rolls and, therefore, the generation of flaws in the rolls is prevented. The discarding regions of the front and rear ends of the sheet bar are decreased and the yield is improved in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a hot sheet bar heating device, and more particularly to a hot sheet bar heating device for heating and rolling a sheet bar.

[Conventional technology]

To explain the conventional method of rolling a hot sheet bar in copper strip rolling, generally speaking, in hot rolling, a heated slab with a thickness of 120 to 300 mm is rolled into a slab with a thickness of 15 to 6011 mm by a rough rolling mill. It is rolled into a sheet bar, which is further rolled to the required product thickness using a finishing mill.

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 conveyance table roller 5, and the tip of the sheet bar is sheared. Next, the sheet bar 3 is transferred to a high-pressure injection type scaling device 11 having a nozzle 8 for removing surface scale, and then the sheet bar 3 is finished rolled by a finishing mill 2 .

During the processing steps from rough rolling to finish rolling, part of the heat held by the hot sheet bar is dissipated into the atmosphere. This amount of heat dissipated increases in proportion to the processing time, so there is a difference in the amount of heat dissipated into the atmosphere between the widthwise side ends and the center of the hot sheet bar, and the temperature of the hot sheet bar is The side end portions in the width direction are lower in temperature than the center portion in the width direction. For this reason, there was a problem in that material defects occurred at the side edges, and the quality of the finish-rolled product deteriorated.

Therefore, in order to solve this problem, as shown in FIG. 7, a circular heater 10, which is a hot seat bar heating device, is used to compensate for the temperature drop at both ends of the seat bar 3. It has been proposed to compensate for the temperature drop at the edge by locally increasing the temperature at the edge of the hot sheet bar (for example, "Tetsu to Hagane" 72nd year (1986), Vol. 2).
No. 1711'7-178).

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

As described above, in the conventional example described above, edge heaters are used to prevent uneven temperature distribution in the width direction of the hot sheet bar 3 between the rough rolling mill 1 and the finishing mill 2. .

[Problem to be solved by the invention]

However, the inventors of the present invention have conducted extensive studies and found that heat dissipation from the seat bar occurs not only at the widthwise ends but also at the longitudinal ends (leading and trailing ends) of the seat bar, resulting in various problems. I found out that

That is, the first problem is that the material at the front and rear ends of the seat bar is defective. The finishing rolling process is normally carried out so that rolling is completed at a temperature higher than Ar=transformation point. However, in the above-mentioned conventional sheet bar rolling method, the local temperature drops at the front and rear ends of the sheet bar are under Ar, which causes abnormal growth of crystal grains, so-called grain gloss. As a result,
In addition to reducing the workability of the product, it also reduces the cold rolling properties, which are often carried out in succession to hot rolling in recent years.

The second problem mentioned above is roll flaws. In a sheet bar made of a steel with high deformation resistance, when the above temperature drop occurs, the roll is plastically deformed when the tip of the sheet bar is bitten by a finishing rolling mill. For this reason, roll flaws may be transferred to the product surface, which may become surface defects and result in defective products. Therefore, it becomes necessary to suddenly replace the rolls, which lowers the operating rate.

In order to prevent the above-mentioned problem, it is necessary to cut off the longitudinal ends of the sheet bar, that is, the front and rear ends, but this poses a problem in that the yield of the product decreases.

Therefore, in order to solve these problems, the present invention improves the yield by preventing material defects at the longitudinal ends of the sheet bar, and also improves the operating rate by preventing the occurrence of roll defects. The object of the present invention is to provide a heating device for a hot sheet bar.

[Means for Solving the Problems] In order to achieve the above object, the hot sheet bar heating device according to the present invention heats the widthwise side ends of the hot sheet bar carried out from the hot rough rolling mill. A heating device for a hot sheet bar heated on the entry side of a finishing rolling machine, comprising sheet bar end detection means for detecting when a longitudinal end of the sheet bar reaches a heating region of the heating device; When the detection means detects the arrival of the longitudinal end of the sheet bar, the conveyance of the sheet bar is stopped or decelerated for a predetermined period of time.
- A bar conveyance speed control means, and a heating device movement control means for moving the heating device across the width direction of the sheet bar during a period when conveyance of the sheet bar is stopped or decelerated.

[Operation] According to the present invention, when the sheet bar end detection means detects the sheet bar longitudinal end, and the sheet bar conveyance speed control means detects the arrival of the sheet bar longitudinal end, The conveyance of the sheet bar is stopped or decelerated for a predetermined period of time, and the heating device movement control means moves the sheet bar in the width direction and heats it. As a result, not only the edges but also the longitudinal ends of the sheet bar are heated before finish rolling. Since it is possible to compensate for the temperature drop in this portion by heating, abnormal growth of crystal grains can be prevented, and as a result, material defects at the longitudinal ends of the sheet bar will not occur. Therefore, compared to conventional hot sheet bar rolling methods, it is possible to improve walkability and improve workability and cold rollability in finish rolling.

Further, as a result of preventing material defects, the roll is not plastically deformed when the tip of the sheet bar made of a steel with high deformation resistance is bitten by the roll, so it is possible to prevent flaws from occurring in the roll.

〔Example〕

Next, embodiments of 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 apparatus of the present invention, in which a seat bar 3 is used instead of the edge heater 10 shown in FIG.
The edges in the width direction (edges) and the edges in the longitudinal direction (
An induction heating device 6 is provided for heating both the front end and the rear end. As shown in the side view of FIG. 1 (al), this induction heating device 6 includes a pair of upper and lower induction heating coils 30A,
30B, this induction heating device 6 further includes a first
As shown in the plan view of Figure (b), two sets are provided in parallel in the width direction of the seat bar 3 (6A, 6B). The output of these induction heating coils can be controlled separately, and the movement 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. 1. Note that the same parts as in FIG. 1 are designated by the same reference numerals, and the explanation thereof will be omitted. FIG. 2 is a side view of the rolling equipment, and to explain its configuration, a high frequency power source 27 is connected to each of the induction heating coils of the induction heating device 6. Furthermore, the induction heating coil includes a coil drive circuit 22 for moving the induction heating device 6 in the width direction of the seat bar 3.
is connected. These coil drive circuit 22 and high frequency power source 27 are connected to the controller 21.

On the upstream side of the induction heating device 6, a tip detector 25 for detecting passage of the tip of the seat bar 3 and a temperature sensor 26 for detecting the temperature of the seat bar 3 are provided. 26 is connected to the controller 21 mentioned above.

Furthermore, a measuring roll 23 for measuring the amount of movement of the sheet bar 3 is connected to one of the transport rollers 5, and a measuring roll 23 for measuring the movement speed of the sheet bar 3 is connected to one of the transport rollers 5. A speed detector 24 is provided. These measuring rolls 23 and speed detector 2
4 is connected to the controller 21.

The controller 21 is configured by a microcomputer, for example, and has 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.

The induction heating device used in this embodiment has a pair of upper and lower induction heating coils 30A, 30, as shown in the side view of FIG.
The upper induction heating coil 3OA is fixed to the tip of the upper support arm 31A. Furthermore, a lower induction heating coil 30B is fixed to the tip of the lower support arm 31B. This pair of upper and lower support arms 31A, 31B are
It is swingably fixed to the left end of the support base 38 of the trolley 32. An opening/closing cylinder 35 is installed on the right side of the upper support arm 31A, and a cylinder 35 for opening and closing is installed on the right side of the upper support arm 31A.
Similarly, an opening/closing cylinder 36 is installed at the right end of the opening/closing cylinder 36 . 33 is a rail formed perpendicular to the rolling line, and 34 is a wheel for moving the cart 32 along the rail.

In addition, 40 is a bearing of the conveyance roller 5.

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

Support arm 31A of the induction heating device shown in FIG.

31B is an induction heating coil 30A provided at the left end;
The length is sufficient to move 30B to the center of the seat bar 3. This induction heating device can be moved on the rail 33 at right angles to the conveyance direction of the sheet bar 3. That is, when moving the induction heating coils 30A and 30B to the widthwise center of the seat bar 3, by running the induction heating coils 30A and 30B toward the seat bar on the rail 33, these induction heating coils are moved to the widthwise center of the seat bar. It is possible to move towards. Note that if the seat bar 3 is warped, the induction heating coil may be destroyed, so by driving the opening/closing cylinders 35 and 36, the supporting arms 31A, 3
1B can be swung around the support shaft 39.

Next, the operation of the embodiment shown in FIG. 2 will be explained based on the flowchart in FIG. 4.

In FIG. 2, the sheet bar 3 is conveyed toward the right side of the drawing, and the tip of the sheet bar 3 is detected by the tip detector 2.
5 (consisting of an infrared sensor, for example), the detector 25 detects the infrared rays of the seat bar 3, and sends a signal of the theoretical value (1) indicating that the tip of the seat bar 3 has arrived to the controller. Output to 21. That is, in step (2) in FIG. 4, it is determined whether the signal SI output from the detector 25 to the controller 21 is the theoretical value (1).

If it is determined that the signal Sl = "IJ" in step ■ above, the process moves to step ■.
Here, the temperature sensor 26 detects the temperature at the tip of the seat bar 3 and sends the detected signal to the controller 21. Note that as the temperature sensor, for example, an infrared thermometer can be used. The controller 21 controls the temperature sensor 2 based on a storage table stored in advance in a storage device.
According to the signal from 6, read the seat bar tip temperature TK. Further, when the controller 21 detects the tip of the sheet bar 3 based on the signal SI from the detector 25, the controller 21 prevents the upper and lower pair of induction heating coils 30A and 30B from being damaged due to the warping of the tip of the hot sheet bar 3. Then, the induction heating coils 30A and 30B are both moved in a direction to be separated from each other.

Next, proceed to step (2). The speed detector 24 outputs a detection signal S3 consisting of a number of pulses corresponding to the rotational speed of the conveyance roller 5, and the controller 21 reads this detection signal S3 and determines the conveyance speed of the sheet bar 3 by counting the number of pulses. calculate.

Next, move to step ■, measuring roll 23
outputs a detection signal S2 consisting of a pulse signal according to the conveyance amount of the sheet bar 3 to the controller 21. By counting the number of pulses, the controller 21 calculates the amount of movement of the seat bar from the point in time when the tip end detector 25 detects the tip of the seat bar. Therefore, by storing the distance from the tip detector 25 to the induction heating coil 6 in advance in the storage device of the controller 21, the time when the tip of the sheet bar 3 reaches the induction heating coil 6 can be detected. can do.

Next, the process moves to step (2), and when it is determined in step (2) that the tip of the sheet bar 3 has reached the induction heating coil 6, the controller 21 outputs a signal to a conveyance control device for the sheet bar 3 (not shown), The tip of the seat bar 3 is stopped between the induction heating coils 30A and 30B for a predetermined period of time.

Next, the process moves to step (2), in which the target temperature previously set in the controller 21 is read by the setting device. Note that the target temperature here refers to the target temperature at the tip of the seat bar 3 after being heated and heated by the coil 6.

Next, the process moves to step (2). In the controller 21, the seat bar tip temperature T read in step
The difference between K and the target temperature T read in step (2) above is calculated.

Next, the process moves to step (2), and the temperature difference (in TeeT) in the above step (2) and the thickness of the sheet bar and the material of the sheet par 3, which are preset in the controller 21, are stored in the storage device of the controller 21 in advance. Based on the stored table, the output of the high frequency power supply 27 which determines the output of the induction heating coil 6 is controlled. That is, the controller 21 controls the high frequency type 'a27 so that the temperature at the tip of the sheet bar 3 detected by the temperature sensor 26 matches the target temperature according to the material and thickness of the sheet bar 3 as well as the conveyance speed. Control output.

Next, proceed to step (2). 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.
A, 6B causes the induction heating coil 6A to approach the induction heating coil 6B to its approach limit value, as shown in FIG. 5(B). The amount of movement of the induction heating coil in the width direction of the seat bar in FIG. By calculating the difference between the control signal and the control signal output to the drive circuit 22 and outputting the control signal from the coil drive circuit 22 to the induction heating coil 6 so that this difference becomes zero, the width direction of the sheet bar of the induction heating device 6 is calculated. The amount of movement can be determined.

Next, as shown in FIG. 5(C), the induction heating coil 6A
and 6B together toward the drawing cloth, and then, as shown in FIG. 5(D), the induction heating coil 6B is further moved toward the left side of the drawing. As a result, seat bar 3
Since the entire widthwise region of the tip portion is heated by the induction heating coil 6, it is possible to compensate for the temperature drop at the tip portion.

The induction heating coil 6 generates an induced current in the seat bar 3 to heat it. The capacity of the induction heating coil can be made smaller as the expected amount of warpage (tolerance) of the tip of the seat bar 3 is smaller. It is necessary to use an induction heating coil. Furthermore, in the case where induction heating is performed with the seat bar 3 running instead of stopping the seat bar 3 and performing induction heating as in this embodiment, a large-capacity induction heating device is required.

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

Next, the process moves to step [phase], where it is determined whether the conveyance stop period of the sheet bar has reached a predetermined time, and if it is determined that the predetermined time has elapsed, that is, time is up, step
to move to.

In this step (2), the conveyance of the sheet bar is resumed, and as shown in FIG. Do it on purpose. Note that after the tip of the hot sheet 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 gap between the induction heating coils 30A and 30B. This greatly improves heating efficiency.

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

In this embodiment, heating of the tip of the seat bar 3 has been described, but the rear end of the seat bar 3 can be heated in the same manner as the tip. At this time, it is necessary to detect the rear end of the seat bar 3, but this is done by setting the length of the seat bar 3 in the controller 21 in advance and adjusting the amount of movement of the seat bar 3 using the measuring roll 23. Since it is constantly monitored, the rear end of the seat bar 3 can be easily heated.

According to the above embodiment, the temperature at the tip of the sheet bar 3 can be accurately raised to the target temperature, so that the temperature drop in the sheet bar 3 can be compensated for, and as a result, abnormal growth of crystal grains can be prevented. , it is possible to prevent material defects at the longitudinal ends of the seat bar.

In this embodiment, the heating device is configured by the induction heating coil 6, and the sheet bar end detection means is configured by the tip end detector 25 and the operation of step (2).
The sheet bar conveyance speed control means is formed by the operation in step (2), and the heating device movement control means is formed by the coil drive circuit 22 and the operations in steps (2) and (2).

A pinch roller can be provided upstream of the induction heating coil shown in FIG. 2 for correcting the warpage of the tip of the sheet bar 3. By correcting the warpage of the tip of the sheet bar 3 and flattening it by the pinch roller, the gap between the upper induction heating coil and the lower induction heating coil in the induction heating device 6 and the sheet bar 3 passing through can be set small. I can do it. Therefore, the capacity of these heating coils can be significantly reduced to reduce equipment costs. Further, there is no need to make the heating coil a movable type that moves 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 end of a sheet bar at 1050° C. that has been rough rolled in a hot rough rolling mill. The graphs in FIGS. 6(A) and (C) show the amount of temperature drop at the tip of the seat bar.
B) and (D) are graphs showing the amount of temperature drop at the rear end of the seat bar. Furthermore, FIGS. 6(A) and C
Graph B) is for heating only the edge portion of the sheet bar, and graphs (C) and (D) are for heating the edge portion and the leading and trailing ends of the sheet bar based on the apparatus shown in FIG. This is a graph when both are heated. In addition,
In FIG. 6, FET indicates the finishing rolling machine entrance temperature,
FDT indicates the finish rolling mill outlet temperature.

The thickness of the sheet bar used in this example was 35 m, and the thickness of the product finished rolled by the finishing mill was 2 mm.

Normally, when the temperature drop at the longitudinal end of the seat bar exceeds 30"C, material defects due to grain gloss usually occur in that part. Therefore, as shown in Figure 6 (A), the tip of the seat bar The material defect area in the area is 5m (
Product equivalent length (the same applies hereinafter)). Further, as shown in FIG. 6(B), the material defective portion at the rear end of the seat bar extends to 2 m. On the other hand, when the temperature is increased by 40'C at the tip of the sheet bar as shown in FIG. 6(C), the defective material portion is reduced to within 2 m from the tip. Further, as shown in FIG. 6(D), the defective material portion at the rear end of the seat bar is reduced to within a range of 1 m. Therefore, by raising the temperature at the longitudinal end of the sheet bar by 40°C, in the case of a general low carbon material with a length of 1,000 m in the longitudinal direction, in the conventional example in which the longitudinal end of the sheet bar is not heated, the temperature at the tip of the sheet bar can be increased by 5 m. And, 2m was cut off at the rear end, but by heating the front and rear end of the sheet bar, the amount of cutting off at the front end is reduced to 2m, and the amount of cutting off at the rear end is reduced to 1m. As a result, the cut-off amount is reduced by 3 m at the leading end and 1 m at the rear end per 1000 m of the seat bar, resulting in a play improvement margin of 0.4%, leading to a significant cost reduction.

In addition, even when a sheet bar made of a steel with high deformation resistance with the leading and trailing ends of the sheet bar heated to 40°C as described above was bitten by a finishing roll 60 times, no flaws were generated in the roll. On the other hand, when a sheet bar made of a steel with high deformation resistance was bitten into a finishing roll 10 times based on a conventional example in which the leading and trailing ends were not heated, it was confirmed that flaws occurred in the roll. .

As can be seen from this specific example, the heating area at the longitudinal end of the sheet bar is approximately 200 mm at the tip.
It can be seen that it is sufficient to heat a width of a little over ++n (sheet bar equivalent length), and it is sufficient to heat a width of about 100 mm (sheet bar equivalent length) at the rear end. However, this does not preclude heating a wider area.

As explained above, according to this embodiment, material defects at the longitudinal end portions of the sheet bar are prevented, and as a result, the yield is improved and it is possible to prevent the rolls from being scratched.

Note that in this example, one induction heating device was used for heating the longitudinal ends of the sheet bar and for edge heating, but these functions were separated and used for edge heating. The device and the heating device for longitudinal end heating can be provided separately.

Further, in this embodiment, the heating device is installed before the crop shear, but the heating device is not limited to this, and it can also be installed after the crop shear.

Furthermore, the number of induction heating devices installed is not limited to that of this embodiment, and more than one heating device can be installed.

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

Further, in this embodiment, the rear end of the seat bar is detected based on a distance tracking method using a microcomputer, but the passage of the rear end of the seat bar can be detected using another optical sensor.

Furthermore, in this example, both the leading and trailing ends of the sheet bar are heated, but from the standpoint of preventing roll flaws and improving performance to some extent, only the leading end of the sheet bar is heated. However, it is also possible not to heat the rear end.

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

In addition, in this embodiment, the conveyance of the sheet bar is stopped,
Although the tip of the sheet bar is heated, the present invention is not limited thereto, and the tip of the sheet bar may be heated by reducing the conveyance speed of the sheet bar for a predetermined period of time.

〔Effect of the invention〕

As explained above, according to the heating device for a hot sheet bar according to the present invention, not only the edge portions of the hot sheet bar but also the longitudinal ends are heated, so that the grain gloss at the longitudinal ends is reduced. As a result, the occurrence of material defects in such portions can be avoided. Therefore, the area where the front and rear ends of the seat bar are cut off is greatly reduced, and as a result, the stop is improved. In addition, in sheet bars made of steel with high deformation resistance, the occurrence of roll flaws can be prevented, and as a result, sudden roll replacement can be avoided, and the operating rate can be improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a hot sheet bar rolling apparatus according to the present invention, FIG. 2 is a block diagram of FIG. 1, and FIG. 3 is a side view showing the configuration of an induction heating device. , Figure 4 is a flowchart showing the operation of Figure 2 above, Figure 5 is a front view showing the method of moving the induction heating coil, and Figure 6 is the sheet bar equivalent length or product equivalent length and temperature drop. FIG. 7 is a side view showing the configuration of a conventional hot sheet bar rolling apparatus. In the figure, l is a hot rough rolling mill, 2 is a finishing mill, 3 is a sheet bar, 5 is a conveyance roller, 6 is an induction heating device 2, 10 is an edge heater, 21 is a controller, 22 is a coil drive circuit, 23 is a measure Ring roll, 24 is a speed detector,
25 is a tip detector, 26 is a temperature sensor, and 27 is a high frequency power source. Figure 1 (G) (b)

Claims (1)

[Claims] (1) In a heating device for a hot sheet bar that heats the widthwise end of the hot sheet bar on the entry side of a finishing rolling machine, the longitudinal end of the sheet bar reaches the heating area of the heating device. a sheet bar end detection means for detecting the arrival of the sheet bar end in the longitudinal direction; and a sheet bar conveyance speed control means for stopping or decelerating the conveyance of the sheet bar for a predetermined period of time when the arrival of the longitudinal direction end of the sheet bar is detected by the detection means. A heating device for a hot sheet bar, comprising: heating device movement control means for moving the heating device across the width direction of the sheet bar during a period when conveyance of the sheet bar is stopped or decelerated.