JPS602926B2 - Control device for correcting warping and warping of rolled plates - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rolling mill, and more particularly to a warpage/downward warpage correction control device for correcting the vertical warpage of a plate material during rolling.

Generally, when rolling a plate material, the tip of the plate material warps upward or downward due to the temperature difference between the front and back surfaces of the material, the difference in the diameter of the upper and lower rolls, the difference in the circumferential speed of the upper and lower rolls, the amount of pickup by the lower work roll, etc. When such upward or downward warping occurs, the former case causes damage to equipment and a reduction in rolling efficiency, while the latter case causes small waves in the sheet, resulting in a reduction in quality. That is, as shown in FIG. 1, the upper backup roll 31 and the lower backup roll 32
Apply vertical pressure to the upper workpiece. When the rolled material 37 is rolled between the roll 33 and the lower work roll 34 and formed into a predetermined thickness, for example, if the lower work roll 34 rotates farther than the upper work roll 33, or the rolled material itself If factors that cause warpage, such as temperature deviation between the upper and lower surfaces, are included, upward warpage will occur as shown in the figure. Note 35,
36 is a motor driven by the upper work roll 33 and the lower work roll 34. Conventionally, a method of controlling the difference in rotational speed between upper and lower work rolls of a rolling mill has been well known in the past in order to solve problems such as upward and downward warping.

However, the conventional method of controlling this rotation speed difference is
The method used was to adjust the rotation speed of one of the rolls based on the rotation speed of the other roll. For example, when accelerating to correct warpage, when the rolling torque was high, Since the current is already flowing close to the current limit, acceleration is not possible and warping cannot be corrected. Therefore, a method was devised in which instead of accelerating one roll, the other roll was decelerated. However, if a difference in roll rotation speed is created using this method, a torque difference will occur between the upper and lower rolls, and the load balance control of the lower roll will be activated, resulting in a torque difference created to correct the warpage. This has the drawback that the rotation speed is controlled in a direction that reduces the warpage, making it impossible to provide a rotational speed difference for correcting warpage. Therefore, if the material temperature is higher on the front side than on the back side, the deformation resistance will be higher on the back side than on the front side, and the top roll load will be smaller than the bottom roll load, so in this state, the conventional top roll and bottom roll are contradictory. If the material is controlled in such a manner that the material warps downward, the lower roll rotational speed is further reduced by the action of load balance control, resulting in the inconvenience that the downward warping is promoted. In contrast, a method has been considered in which a so-called load balance unfavorable zone is provided in which load balance control is stopped if the difference in load (torque) between the upper roll and the lower roll is within a predetermined range.

However, even with this method, the correction effect is not noticeable when the dead zone area is small, and when the dead zone area is increased, the load factor of the drive motor of one roll becomes high, reaching 90% to 100%. It has the following drawbacks. SUMMARY OF THE INVENTION An object of the present invention is to provide a control device for correcting upward and downward warpage of a rolled plate, which can accurately correct upward and downward warpage during rolling within the maximum allowable range of the load factor of the drive motor. .

The present invention has a load balance control function that eliminates the torque difference between the upper and lower rolls due to the difference in circumferential speed between the upper roll and the lower roll and maintains the load balance. The load balance control operation is stopped by controlling the rotational speed of the upper roll and lower roll in opposite ways based on the torque difference between the upper roll and lower roll within a range corresponding to the load rate, thereby preventing upward or downward warpage. The aim is to correct it appropriately.

Examples of the present invention will be described below. FIG. 2 shows an embodiment of the rolling mill warping/downward warping correction control device according to the present invention.

In the figure, an upper and lower roll rotation speed setting circuit 20 is connected to the upper roll speed setting circuit 1 and the lower roll speed setting circuit 2. An upper and lower roll rotation speed command circuit 19 is connected to this upper and lower roll rotation speed setting circuit 2. This upper and lower roll rotation speed command circuit 19 outputs the upper and lower roll rotation speed setting value to the upper and lower roll rotation speed stage setting circuit 20, and outputs the upper and lower roll rotation speed setting values to the upper and lower roll diameter values K and the rolling torque J.
is configured to input. This upper and lower roll rotation speed command circuit 19 uses set values of the upper roll rotation speed V and lower roll rotation speed V2 as command signals based on the value K of the upper roll and lower roll diameters and the value of J at the time of rolling torque. The setting circuit 20' outputs this. Based on the command signal from the upper and lower roll rotation speed setting circuit 20 and the upper and lower roll rotation speed command circuit 19, the upper roll speed setting circuit 1 and the lower roll speed setting circuit 2 are provided with an upper roll rotation speed setting value V,' and a lower roll rotation speed setting value, respectively. It outputs V2'. An upper roll current control circuit 3 is connected to the output end of the upper roll speed setting circuit 1, and an upper roll voltage control circuit 5 is connected to this upper roll current control circuit 3. The output device of this upper roll voltage control circuit 5 is an upper roll thyristor device 7.
is connected to the upper roll thyristor device 7, and an upper roll drive motor 9 is connected to the upper roll thyristor device 7. The upper roll speed setting circuit 1 sets the upper roll speed based on the upper roll rotation speed setting value V,' outputted from the upper and lower roll rotation speed setting circuit 20 and the output value △N, from the load balance dead zone control circuit 12, which will be described later. This value is output to the upper roll current control circuit 3 as a value. The upper roll current control circuit 3 outputs a current value corresponding to the signal from the upper roll speed setting circuit 1 to the upper roll voltage control circuit 5; A voltage value V corresponding to an output current value 1 of is outputted to the upper roll thyristor device 7. The upper roll thyristor device 7 converts the output voltage from the upper roll voltage control circuit 5 into a pulse that determines the firing angle for opening and closing the gates of the plurality of thyristors constituting the upper roll thyristor device 7. The gate is opened and closed, and its output N is supplied to the outside of the upper roll drive motor. On the other hand, a lower roll rotation speed setting value V2' set by the upper and lower roll rotation speed setting circuits 2 is input to the lower roll speed setting circuit 2, which will be described later.

ΔN2 from the -dobalance unfavorable zone control circuit 12 is inputted and outputted to the lower roll current control circuit 4 as a lower roll speed setting value based on these two input values. This lower roll current control circuit 4 outputs a current value 12 corresponding to the lower roll speed setting value from the lower roll speed setting circuit 2 to the lower roll voltage control circuit 6. The lower roll voltage control circuit 6 outputs a voltage value corresponding to the output current value from the lower roll current control circuit 4 to the lower roll thyristor device 8. The lower roll thyristor device 8 converts the output voltage from the lower roll voltage control circuit 6 into a pulse having a conduction rate corresponding to the output voltage, and the on-duty of this pulse opens and closes the gate of the thyristor, and the output value N2 drives the lower roll. Mo-
It will be output on 10pm. The upper roll drive motor 9 and the lower roll drive motor 10' are each provided with an upper roll load factor meter 21 and a lower roll load factor meter 22, respectively. The output terminals of the upper roll load factor meter 21 and the lower roll load factor meter 22 are connected to the load factor determination logic circuit 13. A load balance dead zone setting circuit 14 is connected to this load factor judgment logic circuit 13, and a load balance dead zone setting circuit 14 is connected to one input terminal of a comparator 18 of a load balance dead zone correction control circuit 16. There is. This upper roll load factor meter 21 and lower roll load factor meter 2
Reference numeral 2 detects the load factors of the drive motors of the upper roll and lower roll, respectively, and both of the detected values are input to the load factor determination logic circuit 13. This load factor determination logic circuit 13 determines to which of a plurality of predetermined level ranges the load factor values output by the upper and lower roll load factor meters 21 and 22 belong, and the range to which it belongs is used for load balancing. This is output to the Fuwazai zone setting circuit 14. This load balance dead zone setting circuit 14 determines the load balance dead zone corresponding to the value of the belonging range outputted from the load factor determination logic circuit 13, and this determined value is applied to the comparator 18 of the load balance dead zone control correction circuit 16. is input to one input terminal of. Therefore, for example, if the load factor value is A, in the load factor judgment logic circuit 13, AZ90%,
80%SA<90%, 70%SA<80%, A<70%
The load factor values output from the upper and lower load factor meters 21 and 22 are determined to which category they belong, and are output to the load balance dead zone setting circuit 14. Rate A≧90%
Then, the dead zone is 25%, and if the load factor value A is 80%SA<90%, the dead zone is 50%, and the load factor value A is 70%SA.
If <80%, the dead zone is 75%, and the load factor A is A<70%.
If so, a value corresponding to 100% of the dead zone is output to the comparator 18. The load balance error zone correction circuit 16 includes a load balance error zone detection circuit 17 and a comparator 18.

This load balance unfavorable zone detection circuit 17 detects the current unfavorable zone area, and its detected value is inputted to the other input terminal of the comparator 18. This comparator 18 compares the output value from the load balance unfavorable zone setting circuit 14 and the detected value from the load balance unfavorable zone detection circuit 17, and the difference signal is sent to the load balance unfavorable zone control circuit 12 as △DZ. is output to. The load balance dead zone control circuit 12 has a function of widening or narrowing the current dead zone area based on the output control value from the load balance dead zone correction control circuit 16. In addition, this load balance dead zone control circuit 12 includes a load balance control circuit 1
1 is connected to the load balance control circuit 11, and the output signals from the upper roll speed setting circuit 1 and the lower roll speed setting circuit 2 are input to this load balance control circuit 11. Based on the output signals from the upper roll speed setting circuit 1 and the lower roll speed setting circuit 2, the load balance control circuit 11 performs control so that the torque difference between the upper roll and the lower roll is eliminated. In addition, the load balance unfavorable zone control circuit 12
is for temporarily stopping the load balance control of the load balance control circuit 11, and has a function of widening or narrowing the unfavorable zone area based on the output signal from the load balance unfavorable zone correction control circuit 16, and changes the variable value to It is configured such that the corresponding speed setting values are inputted as △N and △N2 to other input terminals of the upper roll speed setting circuit and the lower roll speed setting circuit 2. If the rolled plate does not warp, the upper and lower roll speed setting circuits 1 and 2, the upper and lower roll current control circuits 3 and 4, and the upper and lower roll voltage control circuits are set based on the upper and lower roll rotation speed setting values preset by the upper and lower roll meters. 5,6
, the upper and lower roll thyristor devices 7 and 8, and the upper and lower roll drive motors 9 and 10 rotate the upper and lower rolls to a set value.

If warpage occurs in the rolled plate, the load factor judgment logic circuit 1 is activated based on the outputs from the upper and lower roll load factor meters 21 and 22.
The level range divided in step 3 is detected, and the load balance dead zone setting circuit 14 outputs the load balance dead zone area to the load balance dead zone correction control circuit 16, where it is compared with the current load balance dead zone and the comparison value is set as the load balance dead zone. It is output to the balance dead zone control circuit 12, and the load balance dead zone control circuit 12 corrects the current load balance dead zone and outputs the corrected value to the upper roll speed setting circuit 1 and the lower roll speed setting circuit 2. . In that case, even if the output signals from the upper roll speed setting circuit 1 and the lower roll speed setting circuit 2 are output to the load balance control circuit 11, the load balance control action is locked by the load balance control circuit 12. Put it away. Therefore, according to this embodiment, upward warping and downward warping can be corrected and controlled within the allowable range of the load factor of the upper and lower roll drive motors.

Further, according to this embodiment, it is possible to significantly improve equipment damage and reduction in rolling efficiency due to upward warpage, as well as damage to equipment and deterioration of the quality of rolled material due to downward warpage.

As explained above, according to the present invention, it is possible to accurately correct upward and downward warping during rolling within the maximum allowable range of the load factor of the drive motors for the upper and lower rolls.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing rolling conditions, and FIG. 2 is a circuit diagram showing an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Upper roll speed setting circuit, 2... Lower roll speed setting circuit, 3... Upper roll current control circuit, 4... Lower roll current control circuit, 5... Upper roll voltage control circuit, S.
...Lower roll voltage control circuit, 7...Top roll thyristor device, 8...Lower roll thyristor device, 9...Top roll drive motor, 10...Lower roll drive motor, 1
DESCRIPTION OF SYMBOLS 1... Load balance control circuit, 12... Load balance unfavorable zone control circuit, 13... Load factor determination logic circuit, 14... Load balance unfavorable zone setting circuit, 15...
- Load factor increase alarm, 16... Load balance dead zone correction control circuit, 17... Load balance dead zone detection circuit, 18... Comparator, 19... Upper/lower roll rotation speed command circuit, 20.・・Upper and lower roll rotation speed setting circuit, 21
... Upper roll load factor meter, 22... Lower roll load factor meter. Figure 1 Figure 2

Claims (1)

[Claims] 1 It has a load balance control function that maintains the load balance by eliminating the torque difference between the upper and lower rolls due to the difference in peripheral speed between the upper and lower rolls. A rolling plate that corrects upward or downward warping by providing a dead zone in which the load balance control operation is stopped within a certain range of torque difference between the rolls, and controlling the rotational speed of the upper roll and the lower roll in opposite directions in the dead zone. A control device for correcting upward and downward warpage of a rolled plate, characterized in that the dead zone of the load balance control can be varied in accordance with the load factor of the vertical drive motor.