JPS63160713A - Automatic plate thickness control method for rolling mill - Google Patents

Abstract

PURPOSE:To improve the accuracy in plate thickness, to reduce an offgage and to improve a yield by outputting a calculated correction value with feedback by synchronizing it with the rolling speed of a plate stock. CONSTITUTION:At the time when sampling times are judged to come up to a specified set value by measuring an inlet side plate length, outlet side plate thickness and rolling speed, it is decided as to whether the set value exceeds an observed value or not by comparing the set value of a speed with the observed rolling speed. In the case of a observed value is lower than a set value, a correction value is calculated by using the set value. The rolling reduction amt. to be corrected is decided so as to make the plate thickness deviation zero always due to the difference being the plate thickness deviation by comparing the calculated inlet side estimated plate thickness with observed inlet side plate thickness and an electro-hydraulic servo valve 30 is controlled according to this rolling reduction amt. The plate thickness accuracy at rolling start time is improved and an offgage is reduced by performing said control procedures until completion of specific passes.

Description

[Detailed description of the invention] [Industrial application field]

The present invention is an automatic rolling mill J! Regarding the Xff and lI control method, measure the decrease in off-gauge of the plate material during acceleration and deceleration of the holding method,
The present invention relates to an improvement in an automatic plate thickness control method for a rolling mill, which is suitable for use in improving plate thickness accuracy. BACKGROUND OF THE INVENTION When manufacturing plate materials such as steel plates, it is necessary to consider plate thickness, plate width, etc. as quality control items. Regarding the technology for controlling the thickness of the plate material, the applicant has already proposed in Japanese Unexamined Patent Application Publication No. 181711/1983 the difference between the calculated outlet thickness deviation and the measured plate thickness deviation, which is averaged over a constant length of the rolled material. A method for automatically controlling the reduction rate of a rolling mill is shown in which the factor of plate thickness error is eliminated by using this value as a feedback correction amount. In this M-holding method, in order to eliminate the steady-state error generated by feedforward control, feedback is provided using the plate thickness deviation (difference between the set value and the actual value of plate thickness) on the rolling slope side as shown below. Control. That is, from the inlet side plate thickness deviation ΔGi, the calculated outlet plate thickness deviation ΔGi (1-r) is calculated by setting the rolling reduction rate as . The thickness deviation (actual output side (U difference) ΔCO) is compared and a correction value is calculated to eliminate the difference, that is, the steady error.In this case, if the comparison is made every sampling, the feedforward Since the predictive control loop for control and the control loop for comparison may interfere and worsen the plate thickness accuracy, a value n is set as the sampling period,
The correction value C is calculated using the following equation (1) for each plurality of samplings. C=(ΣΔcr.Koshi1-fΔG; ・(1-r)), /n・----(t
) 4 work 1 Then, the calculated correction value C is outputted to the plate thickness control system at regular intervals to eliminate error factors.

[Problems to be solved by the invention]

By the way, in the conventional automatic plate thickness ff1j, since the correction value C is determined every time the set value is sampled zero times, feedback correction is performed at a fixed pitch over the entire length of the plate material, for example, the coil. Therefore, at the start of rolling of a plate material, the first feedback correction is not performed unless rolling for a predetermined length is carried out, and while the rolling of the predetermined length is being carried out, deviations in plate thickness and off-gauge are likely to occur. When accelerating or decelerating the rolling speed, the plate thickness, rolling speed, and rolling condition are unstable, so it is necessary to increase the frequency of feedback correction compared to during steady operation. However, with the conventional automatic plate thickness control described above, Since feedback correction is performed, there is a problem in that it is not possible to respond to a request to increase the frequency of feedback correction.

[Purpose of the invention]

The present invention has been made to solve the above conventional problems, and improves plate thickness accuracy by optimizing the output frequency of feedback correction amounts during acceleration and deceleration of rolling where rolling speed and rolling condition are unstable. Another object of the present invention is to provide an automatic plate thickness control method for a rolling mill that can reduce off-gauge plate thickness.

[Means to solve the problem]

The present invention controls a rolling mill with a plate thickness control system so that a predetermined plate thickness is obtained for the plate material to be rolled, detects the actual thickness of the plate material on the exit side of the rolling machine, and calculates the detected actual plate thickness and the target thickness. A rolling mill that calculates a correction value for disturbances in the plate W and control by averaging the difference between plate thicknesses over a certain length, and outputs the calculated correction value as feedback to the plate thickness control system to control the plate thickness. In the automatic plate thickness Mu method, the above object is achieved by feedback outputting the calculated correction value in synchronization with the rolling speed of the plate material.

[Effect]

In the present invention, when performing automatic plate thickness control of a rolling mill, a correction value for the plate thickness control system is fed back and output in synchronization with the rolling speed of the plate material. Therefore, when the rolling speed and rolling condition of the rolling mill are unstable and the rolling acceleration/deceleration is performed, the frequency of feedback output is set to 1 and appropriate, thereby making it possible to improve plate thickness accuracy and reduce off-gauge.

【Example】

Embodiments of the present invention will be described in detail below with reference to the drawings. This example uses the M81I procedure as shown in Fig. 1 to control an automatic plate thickness control device as shown in Fig. 2 to optimize the plate thickness during rolling acceleration. It is something. The reversible rolling mill shown in FIG. 2 includes a payoff reel 12 for unwinding the copper strip 10, a deflector roll 14 for delivering the copper strip 10, and a work roll 16 for rolling the delivered copper strip 10. and a backup roll 18, a deflector roll 20 around which the rolled copper strip 10 is wound, and a tension reel 22 for winding up the rolled copper strip 10.
and will be provided. Further, the automatic plate thickness control device for controlling the reversible rolling mill includes an entry side plate length gauge 24 for detecting the plate length of the steel strip 10 on the entry side of the rolling mill, and An entry side thickness meter 26 for detecting the thickness, a hydraulic cylinder 28 for applying a reduction blade to the backup roll 18, and a hydraulic cylinder 28 for converting an input electric signal into control hydraulic pressure and supplying it to the hydraulic cylinder 28. Electro-hydraulic servo valve 30 and rolled copper strip 10
an exit side thickness gauge 32 for detecting the thickness of the copper strip 10, an exit plate length gauge 34 for detecting the length of the copper strip 10 on the exit side, an input side plate length gauge 24 and an output side plate length gauge 24, and an output side plate length gauge 34 for detecting the length of the copper strip 10 on the exit side. The input side plate thickness is determined from the counter 36 for counting the output Ll and LO signals of the J plate length meter 34 to determine the plate length, and the outputs Hi and h of the input side thickness gauge 26 and the output side thickness gauge 32. A plate thickness deviation output circuit 38 for calculating the deviation ΔGi and the actual output side plate thickness deviation ΔCO, a rolling speed meter 40 for detecting the rolling speed V of the work roll 16, the counter 36, and a plate thickness deviation output circuit. 3
8, and a control device 42 for controlling the electro-hydraulic servo valve 30 based on the output of the rolling speed detector 40 to automatically control the plate thickness. The operation of this embodiment will be explained below. The automatic plate thickness control device shown in FIG. 2 is controlled by executing the control procedure shown in the flow chart shown in FIG. This control procedure is a control procedure for automatically controlling the thickness of the steel strip 10, including during rolling acceleration in the second pass, in a reversible rolling mill as shown in FIG. When using this control procedure in a rolling mill, it is sufficient to first execute this control procedure in the stand. That is, when the control procedure shown in the figure starts, first step 110
So, the length of the entrance board of the bus is 12IJ, step 120
At step 130, the exit side plate thickness GOJ is measured, and at step 130, the rolling speed VJ is measured. The subscript J of these measured values J2ij, GOJ, VJ
indicates the number of sampling times, and when the 0 judgment result of determining whether the sampling number g&j is equal to a predetermined set value n in step 140 is positive, that is, the number of sampling times j has become from zero to the predetermined set value n. When it is determined, the process proceeds to step 150. In step 150, the speed setting value vn corresponding to the setting value n and the actually measured rolling speed V are determined.
n is compared to determine whether the set value vn is equal to or higher than the measured rolling speed vn. The 0 judgment result is positive, that is, the set value V
When fi and the measured rolling speed vn satisfy Vn≦vn, the process proceeds to step 160, and a correction value C is calculated using the above-mentioned equation (1) using the set value n. On the other hand, when the judgment results in the previous steps 140 and 150 are negative, that is, the sampling number j does not reach the set value n, or the actual rolling speed vl is greater than the set value 70 (vn
>vn), the conditions for calculating the correction value C are not yet satisfied, so the process returns to step 110 and continues sampling. And as a result of sampling,
When the conditions of steps 140 and 150 are satisfied, the process advances to step 160 and the process of step 160 is performed. Incidentally, in this control procedure, the relationship between the set value n of the number of samplings for each loop and the set value vl of the speed corresponding to the set value n is as shown in the following table, for example. From Table 1, in the first loop, 1i11 in Figure 1
When the control procedure is executed, when the sampling number j is its set value n = 20 (switch 140), it is determined in step 150 whether the actual rolling speed vn is 201 I/min or less, and if the determination result is positive, At that point, step 160
In step 170, the predicted inlet thickness Gic is corrected using the calculated correction value C and the following equation (2). G>c=(Lo/LI)・(Gos+ΔG+(1−r)l+C・(2) However, COS is the set plate thickness on the exit side. Then, the calculated predicted plate thickness Glc on the input side and the actual measurement The entry side thickness Gi is compared, and since the difference is the thickness deviation to be corrected, the reduction amount ΔX to be corrected is determined so that the thickness deviation is always zero, and the electric oil is adjusted according to the reduction amount ΔX. Controls the servo valve 30. If the set value n = 20 in the first loop and the measured rolling speed v6 = 20 m/min is not entered, the second loop is entered, sampling is continued, and the set value n = 40. If the zero determination result for determining whether the actual rolling speed Vn is 4011/min or less is positive, at that point the correction value C is calculated and the rolling reduction amount ΔX is output. In the subsequent loop, the first The loops shown in the table are executed sequentially and the control procedure shown in Fig. 1 is repeated.Since the sampling set value n is changed for each loop shown in Table 1 as shown in 0 or more, it is synchronized with the rolling speed Vn. It becomes possible to output the reduction amount ΔX as a feedback. In addition, when executing the above control procedure, if the value of the set value n in the first loop is made too small, the feedback it
l+r 0+1 may interfere with the feedforward control loop and may even worsen the plate thickness accuracy. In addition, if the value of the set value n is too large, the set value n is
There is no point in changing it. Therefore, it is necessary to empirically select the optimum setting value n and execute the above control procedure. Table 1 is an example of a far set value n found empirically, and other values can be obtained as appropriate depending on the operating conditions. The above control procedure is performed until the end of the bus (step 18).
0) To improve the accuracy of the plate J at the time of accelerating rolling, for example at the start of rolling, and to reduce off-gauge. Next, the results of controlling the thickness of the copper strip using the method of the present invention are shown below.
s430, a plate width of 1000 nn, and a plate thickness of 1°0111, and the plate thickness was controlled during rolling. As a result of control, the ratio of the plate length where the plate thickness deviation with respect to the plate metal fitting falls within the target plate thickness deviation, that is, the on-gauge rate, is 97.
．． It was 3%. On the other hand, when automatic plate thickness control was performed using the conventional technology that determined the correction value C for each sampling, the off-gauge rate was 96.5%, which was more than 0. Therefore, the method of the present invention was used. In this case, it can be confirmed that the on-gauge rate is improved, that is, the off-gauge rate is decreased, and the yield is improved. In the above embodiments, the method of the present invention was applied to an automatic plate thickness control device of a reversible rolling mill, but the scope of the present invention is not limited to this, and for example, the method of the present invention is applied to an automatic plate thickness control device of a continuous rolling mill. It is clear that the same can be applied to a control device as well. Further, in the above embodiment, the automatic plate thickness control was performed during acceleration, but when carrying out the method of the present invention, it is not limited to only during acceleration, but also applies to rolling mills during transient operation including during deceleration. Automatic board thickness II! Can be adopted by the government.

【Effect of the invention】

As explained above, according to the present invention, it is possible to optimize the feedback output frequency of correction values during rolling acceleration/deceleration when the rolling speed and rolling condition of the rolling mill are unstable, thereby improving plate thickness accuracy and reducing off-gauge. As a result, excellent effects such as an improvement in the on-gauge rate and yield of the entire plate material can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a flowchart showing the plate thickness control procedure of the automatic plate thickness control device in which the present invention is implemented, and FIG. 2 is a cross-sectional diagram including a partial block diagram showing the overall configuration of the automatic plate thickness control device of the embodiment It is a front view. 10... Copper strip, 16... Work roll, 18... Backup roll, 24... Entrance side plate length gauge, 26... Entrance side thickness gauge,
28... Hydraulic cylinder, 30... Electro-hydraulic servo valve, 32... Outlet side thickness gauge, 34... Outlet side plate length gauge, 38... Plate thickness deviation output circuit, 40... Rolling Speed detector, 42...control device.

Claims (1)

[Claims] (1) The rolling mill is controlled by a plate thickness control system so that the plate material to be rolled has a predetermined thickness, and the actual plate thickness of the plate material on the outlet side of the rolling machine is detected, and the detected actual plate thickness and target plate thickness are Automatic plate thickness control of a rolling mill that calculates a correction value for disturbances in plate thickness control by adding and averaging the difference between the two over a certain length, and outputs the calculated correction value as feedback to the plate thickness control system to control the plate thickness. An automatic plate thickness control method for a rolling mill, characterized in that the calculated correction value is output as feedback in synchronization with the rolling speed of the plate material.