JPH0221329B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention mainly relates to a method of controlling a coiler disposed on the exit side of a final finishing stand of a hot rolling line or the like.

After passing through a finishing stand, the strip produced on a hot rolling line is cooled to a predetermined temperature via pinch rolls and then wound onto a coiler without any slack. It is necessary to wind the strip with appropriate tension applied to it. For this reason, the circumferential speed of the pinch roll is normally controlled in synchronization with the final finishing stand, and the winding speed of the coiler is controlled so that the tension of the strip is appropriate. The strip is wound between the final finishing stand, the pinch roll and the coiler, and after the tail of the strip leaves the final finishing stand, tension is applied between the pinch roll and the coiler and the strip is wound onto the coiler. It turns out. By the way, during rolling in the finishing mill, tension is applied to the strip by the coiler while being constrained by the finishing mill and pinch rolls, so the constraining force is strong and the tension is stable, but the tail of the strip is in the final finishing stand. After breaking out of the strip, tension is applied by the coiler under the restraint of the pinch rolls, but due to reasons such as the responsiveness of the rotational speed control of the pinch rolls, the restraining force becomes unstable, the strip is suddenly accelerated, and the coiler There were problems such as variations in the temperature at which the strip was wound and winding errors.

Conventionally, as a countermeasure against this problem, when the tail of the strip leaves the final stand of the finishing mill, the hot run table interposed between the coiler and the pinch roll is decelerated to reduce the friction between the strip and the table roll. A method of using force as a restraining force on the strip to balance the tension by the coiler, a method of tightening the side guides of the strip to balance the tension,
A method of increasing the responsiveness of speed control to the pinch roll to offset the acceleration of the strip, a method of reducing the tension to be applied to the strip, etc. have been proposed.

However, in the above method, slipping occurs between the roll of the hot run table and the strip, which causes scratches on the back side of the strip, and also shortens the life of the roll itself. In addition, when the strip is thin, no binding force can be expected, and warpage occurs on the strip.On the other hand, when the strip is thick, binding force is obtained, but the strip has side flaws and the guide has There is a problem of wear. With the method described above, it is difficult to set the reduction ratio for the pinch rolls, and if the reduction ratio is extremely reduced, there is a risk of slipping between the pinch rolls and the strip, resulting in slip defects.Furthermore, since the method is a preset method, it is difficult to set the reduction ratio for the pinch rolls. This may lead to problems such as sagging of the strip.

The present invention has been made in view of the above circumstances, and its object is to provide a method for controlling a coiler that winds up a strip while applying tension to the strip that is unwound from the final stand of a finishing mill via a pinch roll. , detects the rotational speed of the pinch roll just before and after the tail of the strip leaves the final stand, stores the speed of the pinch roll just before the tail leaves the final stand, and then detects the rotational speed of the pinch roll just before the tail of the strip leaves the final stand. A method for controlling a coiler, characterized in that the speed of the coiler is controlled in accordance with the stored speed, and the speed of the coiler is controlled in accordance with a difference between the stored speed and a pinch roll speed. It is about providing.

The method of the present invention will be specifically explained below based on the drawings showing its implementation state.

The drawing is a schematic diagram showing the implementation state of the method of the present invention together with its control circuit, and in the drawing, 1 is a finishing mill, 2 is a pinch roll, 3 is a coiler, and S is a strip. The strip S is transferred from the direction of the white arrow, passes through a finishing mill 1, a pinch roll 2 driven by a motor _M1 , and then a coiler ₃ driven by a motor M2 with the required tension applied. It's like it's being wound up. Of the stands ST ₁ ... ST ₅ and ST ₆ that make up the finishing mill 1, the final stand ST ₆ is equipped with a command speed generator PG ₁ , and the pinch roll 2 is equipped with a command generator PG ₂ . At times, the output of the finger speed generator PG ₁ is read into the speed control circuit 4 of the pinch roll 2 via a normally closed contact B ₁ inserted in the middle, and also a normally closed contact.
Through B ₂ , the latest data is sequentially replaced with the old data and stored in the memory 5, while the finger speed generator
The output of PG ₂ is input to one terminal of subtracter 6.

The speed control circuit 4 outputs a speed control signal to the motor _M1 to drive the pinch roll 2 at a speed corresponding to the read value of the command generator _PG1 ,
The pinch roll 2 is driven in synchronization with the speed of the final finishing stand ST ₆ . 8 is a tension setting device for the strip S, and when a signal corresponding to the tension to be applied to the strip S is inputted,
The tension control signal is inputted to the tension control circuit 11 via the subtracter 9 and the amplifier 10, and from there a tension control signal according to the set value is output to the motor _M2 of the coiler 3, which drives the coiler 3 at a predetermined speed. It is designed to be wound up while applying appropriate tension.

When the tail of strip S passes through the final stand ST ₆ of finishing mill 1, it is
Detected by a signal from a load detector (not shown) attached to ST ₆ , normally closed contacts B ₁ and B ₂ are opened, respectively, and the memory 5 and command circuit 12 are opened.
the normally open contact A ₁ interposed between the subtractor 6 and the normally open contact A 1 interposed between the
The normally open contact A ₂ interposed between the amplifier 13 and the amplifier 13 is closed.

When the normally closed contact B ₁ is opened, the speed detection value of the finger speed generator PG ₁ attached to the final finishing stand ST ₆ is input to the speed control circuit 4, and when the normally closed contact B ₂ is opened, The input of the detected speed value of the command generator PG ₁ to the memory 5 is cut off. Then, by closing the normally closed contact _A1 , the memory 5
The detected speed value of the finger speed generator PG ₁ just before the tail of the strip S exits the stand ST ₆ stored in is outputted to the command circuit 12 via the normally open contact A ₁ , and the command circuit 12 uses the detected value as the detected value. A corresponding signal is output to the speed control circuit 4, and the speed control circuit 4 outputs a speed corresponding to the signal, in other words, a speed corresponding to the roll speed of the stand ST ₆ just before the tail of the strip S leaves the final finishing stand ST ₆ . A control signal is output to the motor _M1 to maintain the pinch roll 2 at the same time.

However, as mentioned above, due to the delay in the response of the pinch roll speed, etc., the tail of the strip S
By exiting ST ₆ , the restraint of the finishing mill 1 on the strip S is released, so the tension balance of the strip S is disrupted, the strip S is rapidly accelerated toward the coiler 3, and the pinch roll 2 is also increased from the set value. It is in an accelerated state. Therefore, the finger speed generator PG ₂ attached to the pinch roll 2
, and the finger speed generator immediately before the tail of the strip S stored in the memory 5.
The difference with the speed detection value of PG ₁ is calculated by subtractor 6,
A signal corresponding to the speed increase of the pinch roll 2 is input to the amplifier 13 from the normally open contact A ₂ and is amplified.
The subtracter 9 subtracts the signal currently input to the tension setting device 8, calculates the current value for the motor _M2 of the coiler 3 necessary to eliminate the speed increase of the pinch roll 2, and then calculates the current value for the motor M2 of the coiler 3. through motor
A control signal is output to M ₂ to decelerate motor M ₂ , in other words, coiler 3 . This reduces the tension on the strip S, resulting in pinch roll 2
The speed increase is canceled, and the pinch roll 2 is maintained at a normal speed based on the control signal from the speed control circuit 4.

A feedback circuit is provided in the amplifier 13 to prevent the correction output from the subtracter 6 from becoming too large and the tension command signal to the motor _M2 becoming too small, causing the coiler 3 to stop or the tension to the strip S to be insufficient. It is set as.

As described above, in the method of the present invention, when the tail of the strip leaves the finishing mill, the speed of the pinch rolls is controlled in accordance with the memorized speed, and the speed of the pinch rolls is controlled in accordance with the memorized speed. Since the speed of the coiler is controlled according to the difference in speed, the tension of the strip,
The present invention has excellent effects in that the speed is effectively controlled, the strip is stably wound around the coiler all the way to its tail, and there is no variation in the temperature of the strip.

[Brief explanation of drawings]

The drawing is a schematic diagram showing the implementation state of the method of the present invention together with its control system. 1... Finishing mill, 2... Pinch roll, 3... Coiler, 4... Speed control circuit, 5... Memory, 6... Subtractor, 8... Coiler speed setting device, 9... Subtractor, 1
0, 13...Amplifier, 11...Tension control circuit, 12...
Command circuit.

Claims (1)

[Claims] 1. A method for controlling a coiler that winds a strip unwound from the final stand of a finishing mill via a pinch roll while applying tension to the strip,
Detects the rotation speed of the pinch roll just before and after the tail of the strip leaves the final stand, stores the speed of the pinch roll just before the tail leaves the final stand, and after the tail of the strip leaves the final stand, detects the rotation speed of the pinch roll. A method for controlling a coiler, comprising controlling the speed of the coiler in accordance with the stored speed, and controlling the speed of the coiler in accordance with a difference between the stored speed and a pinch roll speed.