JPH04210809A - Method for controlling speed of continuous mill - Google Patents

Abstract

PURPOSE:To stably hold tension between stands by making the best use of the high responsiveness of AC motor by switching a pivot stand to another rolling stand after the tip part of strip reaches a rolling stand on the downstream side from the pivot stand which is taken as speed basis. CONSTITUTION:Each of rolling stands #1, #2, #3 is respectively driven with driving devices 3a, 3b, 3c, the driving device 3c is composed of an AC motor and the driving devices 3a, 3b, etc., are composed of DC motors. One rolling stand of plural rolling stands of rolling mill is determined as a pivot stand for speed basis and the pivot stand is switched to another stand after the tip part of strip 1 reaches the stand on the downstream side from the above- mentioned pivot stand. In this way, at the time of passing of strip that high responsiveness is required as the driving device for continuous mill, the property of AC motor is made the best use, the best use of the property of DC motor is made possible after passing of strip that gradual acceleration is required and tension between stands can be stably held.

Description

[Detailed description of the invention]

[00011

[Industrial Application Field] The present invention defines one rolling stand among a plurality of rolling stands of a continuous rolling mill as a rolling stand that is the key to rolling speed, that is, a pivot stand, and uses the rolling speed of the rolling stand as a reference. The present invention relates to a speed control method for a continuous rolling mill, in which the speeds of the upstream and downstream rolling stands are controlled using suscessive speed correction signals, respectively. [0002] [0002] Conventionally, as a speed control method in a continuous rolling mill, one of the rolling stands constituting the continuous rolling mill is
One rolling stand is defined as a pivot stand whose rolling speed is treated as the reference speed, and the speeds of the other rolling stands on the upstream and downstream sides are determined according to the rolling speed of the pivot stand, and the speed control range of the other rolling stands is determined. A method has been proposed in which, when the rolling stand exceeds its capacity, the pivot stand is changed to another stand to control the speed of all rolling stands within their respective capacities (Japanese Patent Laid-Open No. 58-86).
Publication No. 920). [0003] Conventionally, as a driving device for a rolling mill,
Direct current motors, which are advantageous in terms of speed control, have been used for a long time, but with the recent development of power electronics and computers, AC motors with excellent responsiveness are also being used. In order to improve the thickness and width accuracy of the material, an AC motor is used for the downstream rolling stand, and is used in combination with a DC motor for the upstream rolling stand. [0004]

[Problems to be Solved by the Invention] When continuous rolling is performed, the driving device of the rolling mill is required to have high responsiveness in order to quickly stabilize the tension of the strip during threading.
In addition, in order to maintain the tension of the strip at a constant level under steady operating conditions after the completion of strip threading, the rolling mill must maintain a gradual speed pattern, that is, a well-controlled rolling speed pattern from the front rolling stand to the rear rolling stand. This is necessary. [0005] However, in the conventional speed control method of a continuous rolling mill, the pivot stand is changed when the control range of another rolling stand exceeds the capacity, and the above-mentioned strip threading is Since the rolling mill is changed independently of the operating condition of the continuous rolling mill, such as during regular operation or during steady operation, the following problems arise. That is, [0006]a
) For example, if you select a rolling mill stand driven by a DC motor as a pivot stand, you can take advantage of the high responsiveness of the AC motor and quickly stabilize the strip tension when threading the strip, but at the same time it is difficult to maintain steady operation after threading is complete. Under these conditions, due to the difference in responsiveness between the AC motor and the DC motor, the gradual speed between rolling stands cannot be maintained, resulting in fluctuations in strip tension. [0007] b) In addition, if a rolling stand driven by an AC motor is selected as a pivot stand, the gradual speed can be maintained under steady operating conditions, but during sheet threading, the control is performed by a DC motor with poor response. It takes time for the strip tension to stabilize. [0008] The present invention has been made in view of the above circumstances, and its object is to switch the pivot stand according to the position of the tip of the strip,
In transient conditions such as threading, the high responsiveness of the AC motor is utilized to quickly stabilize the strip tension, and in steady-state operation, the strip tension is maintained stably by maintaining the gradual speed between the stands. The present invention provides a rolling mill control method that can control plate thickness and width with high accuracy. [0009]

[Means for Solving the Problems 1] A speed control method for a continuous rolling mill according to the present invention is such that one rolling stand among a plurality of rolling stands of a continuous rolling mill is a pivot stand that uses the rolling speed of the stand as a speed reference. In a speed control method for a continuous rolling mill in which suscessive speed correction is performed from the pivot stand to an upstream stand and a downstream stand, respectively, the tip of the material to be rolled is placed in a rolling stand downstream from the pivot stand. After reaching the point, the pivot stand is switched to a pond rolling stand. [00101] [Function] According to the method of the present invention, the characteristics of the AC motor can be utilized as a driving device for a continuous rolling mill when high responsiveness is required such as during sheet threading, and gradual speed is required. After threading, etc., it is possible to take advantage of the characteristics of the DC motor. [00111] [Examples] The present invention will be specifically described below with reference to drawings showing examples thereof. FIG. 1 is a block diagram showing equipment for implementing the speed control method for a continuous rolling mill according to the present invention, and #1 in the figure. #2. #3... indicates a rolling stand, 1 indicates a strip, and 2 indicates a winding machine. Strip 1 is unwound from upstream equipment or a coil (not shown), guided to a continuous rolling mill in the direction of the outlined arrow, passes through multiple stands, exits final rolling stand #3, and is wound up by winding machine 2. It looks like this. [0012] Each rolling stand 31. #2. #3 are individually driven by drive devices 3a, 3b, and 3c, respectively. Drive unit 3 of final rolling stand #3
C is constituted by an AC motor, and drive devices 3a, 3b, etc. in the rolling stand on the upstream side thereof are constituted by DC motors. Each drive device 3a, 3b
, 3c are controlled by speed setters 4a and 4b, respectively.
, 4c, and when the strip 1 is threaded, rolling stand #2 is used as the pivot stand to control the speed, and after strip 1 is threaded, the rolling stand #3 is used as the pivot stand. Speed control is performed by a speed control system described below. [0013] The speed control system includes a speed command device 5, a switch 6, calculation correctors 7a, 7b, 7c, adders 8a, 8b,
8c, corrector 11a, llb, 11c1 multiplier 1
2a, 12b, 12c, etc. The speed command device 5 outputs a reference speed for the continuous rolling mill as a speed command signal to the adders 8c, 8a and the multiplier 12b. The switch 6 is configured to switch from the contact 6a to the contact 6b based on the signal from the timing indicator 10, and the holder 9 switches the input at that point when the instruction signal from the timing indicator 10 is input. It is configured to hold the speed command signal that has been set and output the held speed command signal thereafter. [0014] The timing indicator 10 receives a signal from a tracking device (not shown) at the tip of the strip 1;
At the same time or immediately after the leading end of the strip 1 reaches the winder 2, the switch 6. It is configured to output an instruction signal to the cage 9, and the strip 1 to the continuous rolling mill is
When threading the strip, the switch 6 is set to the 6a side and the retainer 9 is set to the non-operating state.On the other hand, after threading is completed, that is, after the tip of the strip 1 is attached to the winder 2, the switch 6 is set to the 6a side. is set to the 6b side, and the retainer 9 is set to the operating state. [0015] The timing indicator 10 transmits the instruction signal not only before or after the end of the passing of the strip 1, but also on the downstream side of the rolling stand #2 where the tip of the strip 1 is a pivot stand. The rolling stand #3 may be opened at any time from the time it reaches the rolling stand #3 located at the rolling stand #3 until it is mounted on the winder 2. Corrector 11a, l
For lb and llc, speed correction coefficients unique to each rolling stand #1 to #3 are set according to rolling conditions based on a rolling schedule. Arithmetic corrector 7a, 7b, 7
c is applied to each rolling stand #1 to # according to changes in rolling conditions due to strip 1 thickness, temperature, looper torque disturbance, etc.
It is configured to calculate the corrected speed of No. 3 and output it. The settings of the pivot stand in the continuous rolling mill will be explained separately for the time of strip passing and the time of steady operation. [0016] <When passing strip 1> When passing strip 1, stand #2 uses a DC motor as drive device 3b.
Use it as a pivot stand to control the speed. Therefore, the switch 6 keeps its contact piece in contact with the contact point 6a. The speed command signal output from the speed command device 5 is input to the multiplier 12b via the switch 6, multiplied by the speed correction coefficient input from the speed corrector 11b, and then sent to the speed setter 4b.
and controls the drive device 3b, rolling stand #2
drive the rolls at a predetermined speed. [0017] Also, the speed command signal output from the speed command device 5 is input to adders 8a and 8c, and the calculation corrector 7a
, 7c and then multiplier 12
a, 12c, and after being multiplied by the speed correction coefficient from the corrector 11a, llc, the speed setter 4a, 4
c, the drive device 3a using a DC motor and the drive device 3C using an AC motor are driven and controlled to roll stand #1. Drive roll #3 at respective speeds. By using the rolling stand #2 driven by the drive device 3b using a DC motor as a pivot stand, the high responsiveness of the rolling stand #3 driven by the drive device 3C using an AC motor can be improved. By taking advantage of this, it is possible to quickly stabilize the tension. [0018] <After the threading of the strip 1 is completed> When the leading end of the strip 1 reaches the winder 2 and is fixed thereto, a switching signal is output from the timing indicator 10 to the switching device 6 and the retainer 9, The contact piece of the switch 6 is brought into contact with the contact point 6b, and the holder 9 holds the speed command signal at that time,
Thereafter, a speed command signal will be emitted from the holder 9 instead of the speed command device 5. The speed command signal output from the holder 9 is input to the multiplier 12c, multiplied by the speed correction coefficient from the corrector 11C, and output to the drive device 3C, thereby driving the rolling stand #3 as a pivot stand. [0019] Also, the speed command signal output from the retainer 9 is input to the adder 8b, and after adding the correction signal from the calculation corrector 7b, it is input to the multiplier 12b and the adder 8a via the switch 6. be done. The speed command signal input to the multiplier 12b is multiplied by the speed correction coefficient from the corrector 11b, and input to the speed setter 4b, which controls the drive device 3b to adjust the rolling speed of rolling stand #3, which is a pivot stand. Rolling stand #2 is driven and controlled at the speed set as the reference speed. [00201 On the other hand, the speed command signal input to the adder 8a is added with the correction signal input from the calculation corrector 7a, and further multiplied by the speed correction coefficient from the corrector 11a in the multiplier 12a. This is input to the setting device 4a, and the driving device 3a is controlled to drive and control the rolling stand #1 at a speed when the rolling speed of the rolling stand #3, which is a pivot stand, is set as the reference speed. The rolling stand #3 is driven by a drive device 3c using an AC motor.
By using this as a pivot stand, it is possible to maintain the gradual speed of the other rolling stands #2, #1, etc. with respect to this, and it becomes possible to easily maintain a steady operating state. Note that speed control similar to that described above is performed for other rolling stands of the continuous rolling mill (not shown). [00211 In addition, in the above-described embodiment, the case was explained in which the rolling stand #2 was used as a pivot stand during sheet passing, and the rolling stand #3 was used as a pivot stand during steady operation.
For example, the rolling stand #1 in a continuous rolling mill that uses a DC motor as a drive device, or other rolling stands as a pivot stand during sheet passing, is not limited to this.
It goes without saying that another rolling stand using an AC motor as a drive device (preferably a rolling stand downstream of the rolling stand that was previously used as a pivot stand) may be used as a pivot stand during steady operation. . [0022] [Effects of the Invention] As described above, in the present invention, since the rolling stand defined as a pivot stand is changed depending on the position of the tip of the material to be rolled, the AC The high responsiveness of the electric motor makes it possible to quickly stabilize the tension, and during steady operation, it is easy to maintain the gradual speed of the rolling stands, and the tension between the stands can be maintained stably. It is effective.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing equipment for implementing the method of the invention.

[Explanation of symbols]

1 Strip 2 Winding machine 3a-3c　　　Drive device 4a~4c Speed setting device 5 Speed command device 6 Switcher 7a-7c Arithmetic corrector 8a~8C adder 9 Cage 10 Timing indicator 11a~11C corrector 12a-12c Multiplier

Claims (1)

[Claims] Claim 1: One rolling stand among a plurality of rolling stands of a continuous rolling mill is defined as a pivot stand that uses the rolling speed of the stand as a speed reference, and a suscessive roll is made from the pivot stand to an upstream stand and a downstream stand, respectively. A speed control method for a continuous rolling mill that performs speed correction, characterized in that the pivot stand is switched to another rolling stand after the tip of the material to be rolled reaches a rolling stand downstream from the pivot stand. How to control the speed of a continuous rolling mill.