JPH0386303A - Rolling reduction control device for rolling mill - Google Patents

Abstract

PURPOSE:To control a hydraulic cylinder at a target position with good accuracy by finding the steady state deviation of the target position and actual position of the hydraulic cylinder in non-rolling stage of a rolling cycle and controlling the position of the hydraulic cylinder based on the corrected steady state deviation in a rolling stage with its correction by a preset quantity. CONSTITUTION:A steady state deviation is subjected to sampling by comparing the set target position and actual position of a hydraulic cylinder in a nonrolling stage on each rolling cycle. A corrected steady state deviation is then found by correcting the steady state deviation by a preset quantity. The position control of the hydraulic cylinder is then performed based on the corrected steady state deviation in a rolling stage. Consequently, the steady state deviation generated in a rolling cycle can actually be offset and the position of the hydraulic cylinder can be controlled with good accuracy at a target position command value.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a reduction control device for a rolling mill, and in particular to a hydraulic reduction control device for a mandrel mill that controls a hydraulic cylinder for positioning a reduction roll. Regarding a control device.

(Prior art) In general, in hot seamless steel pipe manufacturing lines that use stretch reducers in the final finishing process, the cropping allowance becomes large due to the phenomenon of thickening of the tube end due to the stretch reducers, and as a result, the product quality increases significantly. Yield will decrease.

For this reason, during rolling in a mandrel mill, which is a pre-process of the stretch reducer, the tube end of the rolled blank tube is formed thin in advance into a tapered shape to offset the phenomenon of thickening of the tube end in the stretch reducer.

By the way, in a mandrel mill, a plurality of rolling rolls are arranged so as to surround the rolled raw pipe, each rolling roll is driven by a hydraulic cylinder, and the hydraulic cylinder is driven and controlled according to the passage of the rolled raw pipe. The ends of the rolled blank tube are formed into a thin, tapered shape using a reduction roll.

Here, the main points of the conventional reduction control device will be explained with reference to FIG. 4.

During the rolling cycle by the mandrel mill, a target position command value of a hydraulic cylinder (not shown) and a detected position value of the hydraulic cylinder (for example, the position of the hydraulic cylinder is detected by a position sensor) are given to the subtractor 41, and the target position is Subtraction is performed between the command value and the detected position value. As a result, the subtracter 41 outputs the deviation Δε. The deviation Δε is gain compensated by the proportional gain compensator 42 and given to a servo valve (not shown) as a control amount (servo valve opening command value), and the servo valve adjusts its opening according to this servo valve opening command value. degree is adjusted. As a result, the hydraulic pressure sent to the hydraulic cylinder is controlled, and the positioning of the reduction roll is controlled.

(Problem to be Solved by the Invention) By the way, in the case of the conventional pressure reduction control device, since the control is simply performed by feedback control, the deviation in the opening of the servo valve due to changes in oil temperature (neutral (NUL) of the servo valve)
L) Positional deviation), drift of the proportional gain compensator, and disturbances such as friction of the mandrel mill cause a so-called steady position deviation (steady deviation) in the position control of the hydraulic cylinder. That is, as shown in FIG. 5, there is always an isolation between the actual hydraulic cylinder position (indicated by A) and the target position command value (indicated by B) by the amount of the steady position deviation.

As described above, the conventional lowering control device cannot precisely control the position detection value to the target position command value. For this reason, there is a problem that the rolled blank pipe cannot be rolled with high accuracy, resulting in a decrease in product quality and a decrease in yield. In particular, if the positional accuracy of the hydraulic cylinder is poor, tearing or swelling of the tube may occur at the end of the rolled blank tube, making the tube unusable as a product.

An object of the present invention is to provide a rolling mill fI4m device that can control the position of a hydraulic cylinder to a target position command value with extremely high accuracy during a rolling cycle.

(Means for Solving the Problems) According to the present invention, a plurality of reduction rolls arranged in a rolling line are positioned using hydraulic cylinders, and the reduction rolls are positioned in a rolling cycle having a rolling process section and a non-rolling process section. In a rolling control device that is used in a rolling mill that rolls a material in a rolling machine and performs feedback control of the hydraulic cylinder by comparing a preset target position and an actual position of the hydraulic cylinder, a switch means for sampling a steady deviation between a position and the actual position; and a steady deviation correcting means for receiving the steady deviation and correcting the steady deviation by a predetermined amount to obtain a corrected steady deviation; A reduction control device for a rolling mill is obtained, characterized in that the hydraulic cylinder is controlled in the rolling process section based on the corrected steady-state deviation.

(Function) In the present invention, in the non-rolling process section in each rolling cycle,
Sample the steady-state deviation above. Then, this steady-state deviation is corrected by a predetermined amount to obtain a corrected steady-state deviation, and the position of the hydraulic cylinder is controlled in the rolling cycle based on this corrected steady-state deviation.

As mentioned above, the steady-state deviation is corrected in advance to obtain a corrected steady-state deviation so that the steady-state deviation can be compensated for, and the position of the hydraulic cylinder is controlled based on this corrected steady-state deviation in the rolling process section, so the rolling cycle It is possible to substantially cancel out the steady-state deviation that occurs in the position of the hydraulic cylinder, and to control the position of the hydraulic cylinder to the target position command value with extremely high accuracy.

(Example) The present invention will be explained below with reference to Examples.

Referring to FIG. 1, the hydraulic pressure reduction control device according to the present invention includes a deviation calculator (subtractor) 11, a steady deviation compensation circuit 12, and a proportional gain compensator 13, and the steady deviation compensation circuit 12 is equipped with a switch 12a. and a steady-state deviation correction section 12b.

Referring also to FIG. 2, the rolling cycle by the mandrel mill includes a non-rolling process section 22 and a rolling process section 21 following the non-rolling process section 22, and the rolling process section 21 has a standby operation section 21a1 rolling as shown in the figure. It has a tip operating section 21b1 that rolls the tip of the raw tube, a steady rolling section 21C1, and a rear end operating section 21d that rolls the rear end of the rolled tube. In the mandrel mill, when the non-rolling process section 22 is finished, the standby operation section 21a is carried out just before the rolled raw pipe is bitten by the rolling rollers, the tip operation section 21b is carried out at the timing of biting, and then the steady rolling section 21c is carried out. to move to. Then, just before the rolled blank pipe is removed, the rear end operation section 21d is performed, and one rolling cycle is completed. In this way, the rolling cycle is repeated for a plurality of rolled raw pipes in sequence.

As shown in FIG. 1, a target position command value of a hydraulic cylinder (not shown) and a detected position value of the hydraulic cylinder (for example, the position of the hydraulic cylinder is detected by a position sensor) are input to the subtracter 11. Here, the deviation is determined.

In the non-rolling process section 22, this deviation is given to the proportional gain compensator 13, where it receives gain compensation and is input to a servo valve (not shown) as a control deviation (servo valve opening command value). . Then, the valve opening degree of the servo valve is adjusted according to this control deviation, and hydraulic pressure is applied to the hydraulic cylinder via the servo valve. This causes the hydraulic cylinder to position the rolling rolls.

When controlling the hydraulic cylinder as described above, the detected position value does not match the target position command value due to disturbances applied to the control system, and there is always a deviation between the detected position value and the target position command value. reach the state. In other words, a steady-state deviation occurs. In particular, when the hydraulic cylinder is preset, steady-state deviation occurs due to the influence of the above-mentioned disturbance.

Therefore, the switch 12a is closed at the starting point of the non-rolling process section 22. As a result, the steady deviation Δε from the subtractor 11
is applied to the steady-state deviation correction section 12b via the switch 12. Then, at the end point of the non-rolling process section 22, the switch 1
2a is opened, that is, 2m5ec in the non-rolling process section 22,
The steady-state deviation Δε is sampled at each time.

The steady deviation correction section 12b includes a limiter 121 and an integrator 12.
It is equipped with 2. A threshold value (for example, ±1 μm) is set in the limiter 121 in advance, and the limit steady deviation α is output to the integrator 122. This limit steady deviation α is input to an integrator 122, integrated by the integrator 122, and output as an integral value β. Note that the integrator 12
2 has a predetermined threshold value (for example, ±500 μm
) is provided with a limiter (not shown), and as a result, the integral value β is suppressed to this threshold value (
For example, ±500 μm).

In the rolling process section 21, the integral value β is added to the steady-state deviation Δε by an adder 123, and the result is output as a corrected steady-state deviation γ. This corrected steady deviation is gain compensated by the proportional gain compensator 13, and the corrected control deviation (corrected servo valve opening command value) is
as a servo valve. The opening degree of the servo valve is adjusted according to the correction control deviation, and hydraulic pressure corresponding to the correction control deviation is applied to the hydraulic cylinder.

Thereafter, by feedback control, the subtractor 11 sequentially obtains the steady-state deviation Δε, adds the integral value β to obtain a corrected steady-state deviation, and controls the hydraulic cylinder based on this corrected steady-state deviation.

The switch 12a is closed again at the starting point of the non-rolling process section 22 of one rolling cycle, and the steady deviation Δε from the subtractor 11 is
′ is sampled. Thereafter, the switch 12a is opened at the end point of the non-rolling process section 22. The integrator 122 outputs an integral value β' based on the steady-state deviation Δε'. An adder 123 adds the steady deviation Δε' and the integral value β' to output a corrected steady deviation γ'. In the rolling process section 21, the hydraulic cylinders are controlled based on the corrected steady-state deviation γ'.

Similarly, in the non-rolling process section 22, the subtracter 11
The steady-state deviation from the normal deviation is sampled to obtain a corrected steady-state deviation, and the hydraulic cylinder is controlled in the rolling process section 21 based on the corrected steady-state deviation.

In addition, in the non-rolling process section 22, control synchronization is normally 2 m.
Since it exists every 5ec, sampling is performed every 2m5ec. Also, for example, the integrator 122
If the value input to the limiter exceeds ±500 μm, a steady deviation abnormal signal may be output as an alarm.

As described above, since the hydraulic cylinders are controlled in the rolling process section 21 based on the corrected steady-state deviation, the steady-state deviation can be substantially suppressed to near zero. That is, as shown in FIG. 3, the position of the hydraulic cylinder (indicated by C) can be made to accurately follow the target position (indicated by D). Furthermore, even if the disturbance or the like changes in the non-rolling process section 22, that is, even if the steady deviation changes, the corrected steady deviation is calculated based on the steady deviation, so the steady deviation can be corrected with high accuracy. Moreover, since the steady-state deviation is measured during non-rolling, it is possible to capture the true steady-state deviation without being affected by the operation during rolling.

In the above-described embodiments, the case where the present invention is applied to a mandrel mill has been described, but the present invention can be similarly applied to a rolling mill equipped with a rolling roll and a hydraulic cylinder.

(Effects of the Invention) As explained above, in the present invention, the steady deviation is corrected in advance so that the steady deviation can be compensated for, and the corrected steady deviation is obtained.
In the rolling process section, the position of the hydraulic cylinder is controlled based on this corrected steady-state deviation, so the steady-state deviation that occurs during the rolling cycle can be substantially canceled out, and the position of the hydraulic cylinder can be adjusted to the target position command value. This has the effect of allowing extremely precise control.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an embodiment of the hydraulic pressure reduction control device according to the present invention, Fig. 2 is a diagram for explaining a rolling cycle, and Fig. 3 is a diagram showing the hydraulic pressure when using the hydraulic pressure reduction control device according to the present invention. A diagram showing the relationship between the position of the cylinder and the target position, Fig. 4 is a block diagram showing an example of a conventional hydraulic pressure reduction control device, and Fig. 5 shows the position of the hydraulic cylinder when using the conventional hydraulic pressure reduction control device. It is a figure showing the relationship with a target position. 11... Subtractor, 12... Steady-state deviation compensation circuit, 13
...Proportional gain compensator.

Claims (1)

[Claims] 1. A hydraulic cylinder is used to position a plurality of reduction rolls arranged in a rolling line, and used in a rolling mill that rolls material with the reduction rolls in a rolling cycle having a rolling process section and a non-rolling process section. In a rolling control device that performs feedback control of the hydraulic cylinder by comparing a set target position and the actual position of the hydraulic cylinder, a switch that samples a steady deviation between the target position and the actual position in the non-rolling process section. and steady-state deviation correcting means for receiving the steady-state deviation and correcting the steady-state deviation by a predetermined amount to obtain a corrected steady-state deviation; A reduction control device for a rolling mill, characterized in that it controls a cylinder.