JPS5951364B2 - Looper control device for hot rolling mill - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of a looper control device for a hot rolling mill.

In continuous hot rolling mills, the strip tension value between each stand has a large effect on the finished plate thickness accuracy, plate width accuracy 1, and plate shape, and it is necessary to control this tension value constant against various rolling disturbances. has been done.

For this reason, a looper device is installed between each stand.

In addition, in rolling operations, it is also strongly required that the looper position during its operation has a small swing width.

An outline of the looper mechanism and an example of its control using current technology are shown in FIG. 1, and its operation will be briefly described.

In FIG. 1, 1 is a strip, 2 and 3 are rolling stands, 4 is a looper, 5 is a looper system kia, 6 is a looper angle detector, 7 is a looper drive torque calculation device, 8 is a looper drive torque control device, 9 10 is a looper motor current control system, 11 is a looper angle control device, 12 is a mill motor speed control device, and 13 is a mill motor.

In FIG. 1, the chain line frame A is the looper device dynamic system, and the inter-stand strip length (
The inter-stand strip tension value is determined by the looper operating angle θ, the distance between the stands, the loop length (forced length) determined by the mechanical specifications of the looper mechanism, and the Young's modulus of the plate material.

The looper angle also changes depending on the difference between the load torque value on the looper arm, which is determined by the generated tension value and the looper angle, and the generated torque of the looper drive device (hydraulic drive, electric drive).

Next, the chain line frame B is a block for controlling the torque generated by the drive device, and the function is to control the torque amount to always maintain the tension setting value a* in accordance with the operating angle θ (in addition, it controls the amount of torque generated by the strip itself, the looper arm weight, and the torque loss). (including corrections).

The part enclosed by chain line C is the looper angle control (position control) system, which corrects the rolling speed of the adjacent stand according to the difference between the detected looper angle and its set value θ*, and controls the rolling speed by adjusting the strip length between the stands. Feedback control is performed so that the looper angle stably returns to and maintains its set position.

As mentioned above, in the current technology, the raper angle is controlled through the mill rolling speed and the looper system, so the strip tension value fluctuates during the recovery process. The problem was that the response speed was slow and sufficient performance could not be achieved against fast disturbances.

In this regard, there have been attempts to improve this low responsiveness using detectors of strip tension values, and the present invention seeks to provide a more advanced control device for a looper device with a looper angle detector and a strip tension detector. That is.

Now, regarding typical looper machine specifications, regarding changes in mill rolling mill speed and changes in generated torque of the looper drive system,
The frequency characteristics of the influence on the strip tension value σ and the looper angle θ were calculated, and the results were as shown in FIGS. 2 and 3.

If we compare the influences of the rolling speed change command V* and the looper torque command q* on the strip tension value σ from Fig. 2 (in terms of gain characteristics and phase characteristics), we can also see from Fig. Comparing the influences of the rolling speed command V* and the looper torque value command q* on the angle θ, the following fact becomes clear.

i) S) The response of the IJ tube tension value σ is faster when the rolling speed is modified ■*.

ii) The control of the looper angle θ has a faster response when the looper drive device torque amount correction q* is used.

Furthermore, the following facts are important.

1ii) In tension value control, the fluctuation of the looper angle θ is smaller when the rolling speed is corrected than when the torque amount is corrected.

iv) In looper angle control, modifying the looper torque amount has a smaller effect on the strip tension value σ than modifying the rolling speed.

The above properties do not depend on the dimensions of the looper mechanical system, the responsiveness of the mill/looper drive system, or the rolling conditions, and are universal characteristics that always hold true for both hydraulic loopers and electric loopers.

Therefore, it is clear that the looper control device according to the present invention is superior to the conventional method in that it can control the tension value deviation by modifying the rolling speed and control the looper angle by modifying the looper torque amount, and can expect high-speed response in both cases. Furthermore, when using both control functions together, it is a big advantage that the influence of each on the other (mutual interference) is small, which improves the accuracy of finished plate thickness,
This can make an extremely large contribution to sheet width accuracy, shape change, and sheet threading stability.

A fourth embodiment of the looper control device for a hot rolling mill of the present invention is shown in the fourth embodiment.
As shown in the figure.

The looper angle control device 11 adjusts the amount of torque of the looper drive device according to the difference between the signal from the looper angle detector 6 and its reference angle θ*, and maintains the looper operating position appropriately.

The tension control device 15 adjusted the stand rolling speed according to the difference between the signal from the tension detection device 14 and its standard set value a*, and maintained the strip tension value σ appropriately.

The principle of tension value detection is that it is possible to use a looper device or to use the estimated calculation results from the rolling torque, rolling force, mill motor rotation speed, etc. in the front and rear stands. This is applicable to both loopers.

As described above, according to the present invention, in the looper device installed for controlling the strip tension value in a continuous hot rolling mill, when the detected tension value has a deviation from the set value, the adjacent tension value is adjusted according to this deviation. This was corrected by adjusting the rolling speed of the stand, and when the looper operating angle position deviated from the set position, it was corrected by adjusting the amount of torque generated by the looper drive device according to this deviation. Therefore, it is possible to realize a looper control device for a hot rolling mill with high precision and quick response.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the looper control device of a conventional hot rolling mill, Fig. 2 is a diagram showing the frequency characteristics of the effect of looper torque change q and rolling speed change V on strip tension value σ, and Fig. 3 4 is a diagram showing the frequency characteristics of the influence of the looper torque amount q and rolling speed V on the looper angle θ, and FIG. 4 is a block diagram showing an embodiment of a looper control device for a hot rolling mill according to the present invention. In the figure, 1 is a strip, 2 and 3 are rolling stands, 4 is a looper, 5 is a looper system gear, 6 is a looper angle detector, 7 is a looper drive torque calculation device, 8 is a looper drive torque control device, and 9 is a looper drive torque controller. Looper motor current control system, 10
11 is a looper motor, 11 is a looper angle control device, 12 is a mill motor speed control device, 13 is a mill motor, 14 is a tension value detection device, and 15 is a tension control device. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] 1. In a looper device installed to control the strip tension value in a continuous hot rolling mill, when the detected tension value has a deviation from the set value, the rolling speed of the adjacent stand is adjusted according to this deviation. This is corrected, and when the looper operating angle position deviates from the set position, it is corrected by adjusting the amount of torque generated by the looper drive device according to this deviation. looper control device.