JPS6321566B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for setting the roll opening of a rolling mill, and in particular, it is suitable for initially setting the roll opening of a thick plate rolling mill. This invention relates to an improvement in a method for setting the roll opening of a rolling mill using both a mechanism and a hydraulic reduction mechanism.

Generally, in a reversible rolling mill, the roll opening degree, side guides, etc. are set for each rolling pass, and the time required for this initial setting is a very important factor related to rolling efficiency.

Conventionally, as an initial setting method for the roll opening degree, in an electric rolling mill, the initial setting is performed by switching between a rough reduction motor and a fine reduction motor. That is, a high-speed roughing down motor is used in a pass that requires a large stroke, and a roughing down motor is used in a rolling pass that requires a small stroke and setting accuracy, but each motor has its advantages and disadvantages. That is,
Although the coarse reduction motor has high speed, it does not provide high setting accuracy. On the other hand, the coarse reduction motor has high setting accuracy but is slow. Therefore, the stroke is large,
In passes that require setting accuracy (for example, the final tenter pass), settings must be made at the expense of either accuracy or setting time.

Even in hydraulic rolling mills, since the stroke of the hydraulic cylinder is limited, the initial setting of rolling is generally performed by electric rolling, which also has the above-mentioned drawbacks.

To solve the above-mentioned drawbacks, Japanese Patent Application Laid-Open No. 55-73412 discloses a roll opening control method for a rolling mill in which an upper roll and a lower roll are rolled down by an electric rolling mechanism and a hydraulic rolling mechanism. to roughly set the roll opening, and while the operation of the electric rolling down mechanism has not completely stopped, the hydraulic rolling down mechanism starts finely setting the roll opening, thereby setting the roll opening of the upper roll and the lower roll. A system has been proposed in which both of the above mechanisms are used. However, in this roll opening degree control method, not only is a specific control method for the hydraulic reduction mechanism not disclosed, but also regarding the control method for the electric reduction mechanism, there is a positional deviation between the reduction setting value and the roll opening degree. Since the deceleration output is not output to the screw down motor until the final set value is reached, and the deceleration output is immediately brought to zero when the position deviation falls within a predetermined value, the overshoot of the electric screw down tends to be excessive. It had a point.

The present invention has been made in order to eliminate the above-mentioned conventional drawbacks, and provides a method for setting the roll opening of a rolling mill, which allows highly accurate rolling reduction setting in a short time, and which causes less overshoot. With the goal.

The present invention provides a roll opening setting method for a rolling mill in which the roll opening is set by both an electric rolling down mechanism and a hydraulic rolling down mechanism, in which the deviation between the rolling set value RGr, that is, the target value of the roll opening and the roll opening RGf is provided. ε
(=RGr−RGf), a maximum speed command is output to the rough reduction motor of the electric reduction mechanism until the deviation ε becomes below the first predetermined value, and the deviation ε becomes below the first predetermined value. After the deviation ε becomes equal to or less than a second predetermined value, a deceleration command is output to the coarse reduction motor, and when the deviation ε becomes equal to or less than a second predetermined value, a stop command is output to the coarse reduction motor. The above objective was achieved by outputting a cylinder position command CPr expressed by the following formula CPr=α∫εdt+βε (α is an integral gain, β is a proportional gain) to the hydraulic cylinder of the hydraulic lowering mechanism. It is something.

Here, CPr is the manipulated variable of the PI (proportional, integral) feedback control system. That is, it is a PI controller output for making the deviation ε between the control target value (RGr) and the process actual value (RGf) zero.

The overshoot of the electric lowering mechanism is RGr
This is one factor that causes the discrepancy between RGf and RGf. It is clear from feedback control theory that the PI controller can control ε to zero without generating an offset. Therefore, it is also clear that equation (2), which is the PI controller output, provides the operation amount (that is, the hydraulic cylinder movement amount) that compensates for the overshoot.

Although Equation (2) does not give an integral limit, this depends on the dynamic characteristics of the plant to which the present invention is applied (response of the pressure reduction system response controller, sampling time during digital control, etc.), so it is intentionally expressed. Not yet. Whether an integration limit is provided or not is not directly related to the gist of the present invention.

Embodiments of the present invention will be described in detail below with reference to the drawings. In this embodiment, as shown in FIG. 1, an upper work roll 12a, an upper back-up roll 14a, a lower work roll 12b, which are respectively arranged above and below the rolled material 10, roll down the rolled material 10.
The upper work roll 12a is passed through the lower back up roll 14b and the upper back up roll 14a.
A screw-down screw 18 that lowers the screw, a rough-down motor 20 that drives the screw-down screw 18, and a rough-down motor speed control device 2 that controls the rough-down motor 20.
2 and the lower work roll 12b via the lower back up roll 14b.
A hydraulic pressure reduction mechanism 24 consisting of a hydraulic cylinder 26 that reduces (presses up) the hydraulic pressure, a hydraulic servo valve 28 that controls the flow rate and direction of oil supplied to the hydraulic cylinder 26, and a hydraulic pressure supply device (pump, tank, accumulator, etc.) 30. A plate rolling mill comprising: an electric rolling position detector 32 for detecting the amount of movement due to electric rolling of the upper work roll 12a from the rolling position of the rolling screw 18; A hydraulic cylinder position detector 34 detects the amount of movement due to hydraulic pressure reduction of the hydraulic cylinder position detector 12b, and a roll opening degree RGf (vertical Roll opening calculator 36 that calculates the work roll gap)
, a reduction setter 38 usually composed of a process computer, which calculates a reduction set value RGr (roll opening degree reference) from various rolling conditions, and a reduction setting value RGr output from the reduction setting device 38 and the roll opening degree calculator. Based on the roll opening degree RGf of the 36 output, the second
As shown in the figure, the deviation ε between the two calculated by the following formula ε=RGr−RGf (1) is equal to the first predetermined value ε ₁
A maximum speed command is output to the coarse reduction motor speed control device 22 of the electric reduction mechanism 16 until the deviation ε becomes equal to or less than the first predetermined value ε ₁ , and then the second predetermined value ε For example, a stepped deceleration command is output to the coarse reduction motor speed control _device 22 until the deviation ε becomes equal to or less than a second predetermined value ε ₀ , the coarse reduction motor speed is outputted. Control device 2
At the same time as outputting a stop command to 2, the target value for controlling the hydraulic cylinder 26 of the hydraulic pressure lowering mechanism 24 is expressed as follows: CPr=α∫εdt+βε (2) (α is integral gain, β is proportional gain) Outputs the cylinder position command CPr shown by
For example, depending on the roll opening control device 40 consisting of a microcontroller, and the deviation between the cylinder position command CPr output from the roll opening control device 40 and the hydraulic pressure reduction position output from the hydraulic cylinder position detector 34,
A hydraulic cylinder position control device 42 for controlling the valve opening degree of the hydraulic servo valve 28 of the hydraulic pressure lowering mechanism 24 is provided.

The action will be explained below. At the timing of starting the roll-down setting given by the roll-down setting device 38, the roll opening degree control device 40 first drives the rough-down motor 20 of the electric roll-down mechanism 16 to start rough setting. That is, the roll opening deviation ε is calculated from the roll opening setting value RGr output from the roll setting device 38 and the roll opening RGf output from the roll opening calculation unit 36 according to the equation (1) above.
A speed command for the roughing down motor 20 according to this deviation ε is output to the roughing down motor speed control device 22. Specifically, when controlling the roughening pressure digitally, for example, as shown in _FIG . After the deviation ε becomes equal to or less than the first predetermined value ε ₁ , the second predetermined value ε ₀ is output.
A step-like deceleration command is output to the coarse reduction motor speed control device 22 until the deviation ε becomes equal to or less than the second predetermined value ε ₀ , the coarse reduction motor speed control device 22 Outputs a stop command to. Here, the first predetermined value ε ₁ and the second predetermined value ε ₀ are appropriately determined based on the response characteristics of the roughening motor 20. For example, ε ₁ and ε ₀ are values that satisfy the following.

ε ₁ > ε ₀ ε ₁ : Determined by the response characteristics of the rough reduction motor. Deceleration/
If the amount of downward movement from when the stop command is output until the actual stop is ΔS, O<ε ₁ −ΔS<STmax However, STmax is determined within the range of hydraulic cylinder allowable stroke amount.

ε ₀ : determined in the range O<ε ₀ <STmax.

Approximate values of ε ₁ and ε ₀ are determined within the above range, and then determined by trial and error so that the rolling reduction setting time is minimized. However, with only the reduction setting using this electric reduction mechanism 16, even if a stop command is received, the rough reduction does not stop instantaneously due to inertia, etc., so there is a certain amount of overshoot, and this overshoot amount There are also variations in the time it takes to completely stop. Further, since this overshoot amount varies, ε ₀ for stopping the rough reduction according to the target value cannot be uniquely determined. Therefore, in the present invention, the hydraulic pressure reduction mechanism 2 is activated at the timing at which the stop command to the rough reduction motor 20 is output (that is, at the timing at which it is detected that the deviation ε has become equal to or less than the second predetermined value ε ₀ ).
4 starts controlling the hydraulic cylinder 26. That is,
The cylinder position command CPr is calculated by performing proportional integration as shown in the equation (2) above for ε obtained from the equation (1) above.
is determined and output to the hydraulic cylinder position control device 42. Here, the integral gain α and the proportional gain β in the above equation (2) are both determined by the responsiveness under rough pressure and under hydraulic pressure.

FIG. 3 shows the relationship between the movement of the upper and lower work rolls and the setting timing when using the roll opening setting method according to the present invention. In Fig. 3, the solid line A indicates the movement of the upper work roll due to the rough electric reduction, and the solid line B
indicates the movement of the lower work roll due to hydraulic pressure,
Time t ₁ is the timing to start rolling reduction setting, time t ₂ is the timing when the roll opening deviation ε = ε ₁ , and the timing to start decelerating the coarse electric reduction, and time t ₃ is the timing when the roll opening deviation ε = ε ₀ . , timing for outputting a stop signal for rough electric pressure reduction and starting control for hydraulic pressure reduction;
At time t ₄ , the gap between the upper and lower work rolls is the set value RGr
The setting completion timing according to the present invention, time _t5 , which is equal to , is the stop timing of the upper work roll, which was the conventional setting completion timing only by rough electric reduction. As is clear from the figure, with only coarse electric pressure reduction, after the stop signal is output, there is an overshoot by position C, and a setting error as shown in D remains, whereas according to the present invention, the time
The setting error has already been resolved at t ₄ . or,
Since the hydraulic cylinder is made to perform the same movement as the rough electric reduction from time _t4 onwards, there is no need to know the time _t5 when the rough electric reduction actually stopped, and the footback only needs to be the roll opening degree.

In the above embodiments, a hydraulic plate rolling machine in which a hydraulic cylinder drives a lower work roll is described, but a hydraulic plate rolling machine in which a hydraulic cylinder drives an upper work roll, or a general hydraulic plate rolling machine is described. It is clear that the present invention is similarly applicable to type rolling mills.

As explained above, according to the present invention, highly accurate reduction setting can be performed at high speed, and there is little overshoot. Further, since the setting time may be short, rolling efficiency is improved. Furthermore, since the setting accuracy is high, it has excellent effects such as improved plate thickness accuracy, yield, quality, etc.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the overall configuration of a plate rolling mill in which an embodiment of the roll opening setting method for a rolling mill according to the present invention is adopted, and FIG. 2 shows roll opening deviation in the embodiment. FIG. 3 is a diagram showing the relationship between the elapsed time and the position of the upper and lower work rolls in the same embodiment. 10... Material to be rolled, 12a, 12b... Work roll, 14a, 14b... Backup roll, 16... Electric rolling down mechanism, 18... Rolling screw, 20... Rough rolling motor, 22... Rough rolling motor Speed control device, 24...Hydraulic lowering mechanism, 26
......Hydraulic cylinder, 28...Hydraulic servo valve, 3
0...Hydraulic supply device, 32...Electric reduction position detector, 34...Hydraulic cylinder position detector, 36...
Roll opening degree calculator, 38... Roll setting device, 40...
...Roll opening degree control device, 42...Hydraulic cylinder position control device.

Claims (1)

[Scope of Claims] 1. In a rolling mill roll opening setting method in which the roll opening is set by both an electric rolling down mechanism and a hydraulic rolling down mechanism, the roll opening setting value RGr and the roll opening are
According to the deviation ε (=RGr−RGf) from RGf, a maximum speed command is output to the rough reduction motor of the electric reduction mechanism until the deviation ε becomes equal to or less than the first predetermined value, and the deviation ε After the deviation ε becomes equal to or less than the second predetermined value, a deceleration command is output to the coarse reduction motor until the deviation becomes equal to or less than the second predetermined value. In addition to outputting a stop command to the lowering motor, a cylinder position command CPr expressed by the following formula CPr=α∫εdt+βε (α is an integral gain and β is a proportional gain) is output to the hydraulic cylinder of the hydraulic lowering mechanism. A special method for setting the roll opening of a rolling mill.