JPS6030514A - Rolling machine control system - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control system for controlling the operation of a rolling mill to improve the running of material being rolled through the nip between the rolls of a rolling mill.

When rolling a metal workpiece, the workpiece must be rolled in a small amount (both 1
It passes between a pair of rolls on two rolling mill stands. The workpiece is passed forward and backward through the same rolling mill to gradually reduce the thickness of the workpiece, or through multiple stands arranged in tandem. In particular when rolling metal strips, tandem stands are used, it being observed that the speed with which the strip passes through the stands increases as the thickness of the strip decreases.

Therefore, in the last stand the strip may run at high speed. For effective rolling without failure,
It is important that the running strip passes approximately through the center of the two mill housings of each mill stand as it passes between the rolls. If this does not occur and the strip gradually moves from this central path towards one of the housings, the strip could hit the fixed side guides on the mill housing, damaging both the strip and the mill structure. be.

The rolling mill is equipped with a gauge control system that automatically controls the roll gap of the rolling mill stand to account for the elongation of the housing under load (5tretches) and changes in temperature and hardness of the strip material. It is well known that

In a rolling mill that has a fluid pressure cylinder in each housing to adjust the roll gap, the gauge setting required for the rolled material is determined by positioning the rolls that make up the roll gap and by adjusting the housing during rolling. This is done by measuring the load applied to the load using a separate transducer. These signals are modified by shaping circuits and scalers to represent the elongation of each mill housing.
Additionally, feedback is provided to a position control loop associated with each housing to compensate for rolling mill expansion with hydraulic cylinders. By controlling the magnitude of the signal fed back to each position control loop, the apparent stiffness of the rolling mill can be changed from a natural stiffness where the extension signal feedback is zero to infinite where the extension signal completely compensates for the actual extension of the rolling mill. Rigidity (1nfinitely
5tiff).

Rolls in rolling mills are eccentric to some degree, and even though modern rolls are made to high tolerances, there is always some eccentricity between the rolls when they are assembled into the bearings of a mill stand. When the gauge control circuit is activated and the apparent stiffness of the rolling mill approaches infinity, the effect of the eccentricity of the rolls is imprinted on the strip material, and the gauge of the strip material changes periodically along its length. do. In softer rolling mill housings, this eccentricity effect is less pronounced.

One object of the present invention is to
It is an object of the present invention to provide a control circuit for controlling the operation of a rolling mill in order to improve rolling mill acceleration.

Another object of the invention is to provide a control circuit for controlling the operation of a rolling mill having hydraulic cylinders within each housing to improve the strike of the workpiece being rolled.

In accordance with the present invention, a pair of housings, at least two rolls supported within the housing at opposite ends, and a pair of hydraulic cylinders, one associated with each housing to vary the roll gap, are provided. A control system for a rolling mill having a pair of control circuits for controlling the operation of each cylinder, means for generating a signal representative of the load applied to each housing, and means for generating an average value of the signals for each of the control circuits. and means for detecting a difference between the signals, if any, to generate a difference signal representing the difference, and supplying the difference signal to one of the control circuits; By providing signals of equal amplitude and opposite polarity to the other control circuit, the control circuit is configured to increase the load on the highest load housing and decrease the load on the lowest load housing.

In order that the invention may be more easily understood, it will be described below, by way of example only, with reference to the accompanying drawings, which schematically show a control system for a rolling mill.

A rolling mill 1 suitable for rolling metal workpieces such as aluminum strip strips has two spaced apart housings 3 rotatably supporting a pair of work rolls 5 . Each housing includes a hydraulic cylinder in the form of a capsule 7 which operates between a fixed part of the housing and a bearing chock of one of the rolls to adjust the roll gap 9 by adjusting the position of the rolls. do. Some form of device is provided within each housing to measure the load on each housing. This is a load cell or converter 11
, which produces an electrical signal indicative of the fluid pressure exerted on the capsule.

Each housing has a control circuit 13 associated with it. Each control circuit 13 basically automatically controls the gauge of the workpiece rolled in the rolling mill, and includes a summing amplifier 15, a scaler 17, and a backlash generator 1.
Contains 9. The signal from the transducer 11 representing the load on the housing is supplied to the scaler 17 after being slightly modified by a backlash generator 19 to account for the stiction present in the fluid pressure pump 7. .

This scaler 17 stores information representing the expansion of the rolling mill housing. The relationship between elongation and load is not linear and is based on test results of the rolling mill housing. Scaler 17
The signal supplied to the scaler 17 represents the load on the housing and the output of the scaler 17 represents the elongation of the housing. This output is fed to one input of summing amplifier 150. Another input receives a signal representative of the desired gauge of the workpiece.

The output of the summing amplifier is used to control a hydraulic cylinder within the housing to position the end of the roll within the housing.
act. Under normal rolling conditions, with the workpiece approximately in the center of the roll gap 9, the loads on the two housings are approximately equal. If the temperature of the incoming workpiece changes or the gauge on the entry side of the workpiece changes,
The load on the Ujifugu also varies and the capsule is controlled by a control circuit to produce a substantially constant gauge.

When the workpiece entering the rolling mill deviates from the center of the rolling mill toward one housing, the load applied to that housing increases slightly, and the load applied to the other housing decreases slightly. These load changes are detected by transducer 11 and a signal is sent to scaler 17 which produces an output signal representing the extension of the mill to the new load. By means of the summing amplifier 15, the capsule 7 is controlled in such a way that it further increases the load on the housing to which the workpiece approaches and further decreases the load on the other housing. However, the change in the signal from the summing amplifier 15 is controlled by the stretch of the rolling mill determined by the scaler 17, and the change in the load on the two housings is insufficient to return the workpiece to the center position of the nip. It is.

The control circuit of the invention includes a connection 21 between corresponding inputs of two summing amplifiers 15.

This means that the output signal from the scaler 17 is equalized and the same signal is applied to both summing amplifiers. In other words, an average value of the two outputs from the scaler is obtained and this average value is fed to each summing amplifier. Further, the two signals from the converter 11 are transmitted to the differential amplifier 2.
3, which produces an output signal representing the difference in the load on the two housings. The gain of the differential amplifier 23 is completely independent of the scaler 17, and its output is passed through a dead band filter 25 to one of the summing amplifiers 150.
Sent to input. The output of the deadband filter is also sent via inverter 27 to the other summing amplifier 150 input. The purpose of the inverter 270 is to combine two summing amplifiers 1
The purpose is to ensure that the inputs applied to the terminals 5 and 5 have the same amplitude and opposite polarity. Deadband filter 25 merely produces an output with unnecessary pull removed. The outputs of the differential amplifier 23 are configured such that a positive output is applied to the housing experiencing the most load to increase its load, and a negative output is applied to the housing experiencing the least load to decrease its load. . By appropriately adjusting the gain of the differential amplifier 15, the magnitude of the signal applied to the summing amplifier 15 can be varied enough to change the load on the housing to direct the workpiece to the correct path through the center of the mill. It will push back to

An example of the operation of the rolling mill is shown below.

(a1 If the present invention is not used, the rolling mill rolls the metal strip, and the load on each housing is 7
It weighs 36 tons. Findings from testing indicate that the extension of each housing under this load is 4.048 myn. To compensate for 100% of this elongation, the roll gap was increased to 4
．． The scaler is set to control the fluid pressure pulse in each housing to adjust by 0.048 mm. Therefore, the rolling mill elongation is. It is known that if the workpiece is displaced from the center of the rolling mill towards one housing, the load difference between the two housings is 50 tons.

It is reasonable to assume that one housing will be subjected to a load of 736+25=761) tons and the other will be subjected to a load of 736-25=711) tons.

The two control circuits try to squeeze the workpiece back to the center of the mill, but since the scaler 1T is set at 182 tons/mm, the load on one housing is equivalent to the mill extension. and the load on the other housing is reduced to correspond to the mill extension of .

Actually, this 4.18-3.90 = 0.28mm
It was found that the roll gap difference was insufficient for squeezing the workpiece back to the center of the rolling mill.

(b1 When using the present invention, the rolling mill rolls the metal strip, and the load on each housing is 7
It weighs 36 tons. Findings from testing indicate that the extension of each housing under this load will be 4.048 mm. To compensate for 100% of this elongation, the roll gap was set to 4-0.
The scaler is set to control the hydraulic cylinders in each housing to adjust by 48 mnt. therefore,
The elongation of the rolling mill is. It is known that if the workpiece is displaced from the center of the rolling mill towards one of the housings, the load difference between the two housings is 50 tons.

One housing receives a load of 761 tons and the other receives a load of 761 tons.
It is reasonable to estimate that it will carry a load of 11 tons.

However, the output of the differential amplifier 23 represents 50 tons, and the gain of this amplifier is adjusted until the workpiece is pushed back to the center of the mill. To do this,
Move each capsule by 0.28 mm to make the roll gap in one housing 4.048 + 0.28 = 4.
It was found that the roll gap in the other housing had to be varied to 4.048-0.28=3.76F3tnm. The differential amplifier 230 gain is completely independent of the output of the scaler 17 with a common (corrmon) stiffness setting.

The difference between the two capsules giving a roll gap difference of 0.56 mm would, without the present invention, be compensated for by more than 100 inches of mill elongation, i.e. by an amount greater than the roll elongation. can only be obtained by adjusting the roll gap. Such adjustment not only causes gauge errors in the rolled workpiece, but also increases the influence of roll eccentricity on the workpiece.

Although the control system described above operates the rolling mill in such a way as to prevent the workpiece from turning and shifting to either side of the housing, the control system of the present invention operates when rolling an all-pole workpiece. can be used in other ways to solve problems that often arise. When the cross section perpendicular to the length of the workpiece becomes tapered, the workpiece undergoes a "banana-shaped deformation" when leaving the rolling mill. That is, it curves toward the negative side. This is because conventional automatic gauge control systems attempt to level the workpiece (adjust the loads on the two housings).

This problem is solved by adjusting the output of the differential amplifier 23 to provide a positive output to the lowest load to increase it and a negative output to the highest load to decrease it. be able to. With this configuration, the so-called "banana" effect is avoided because the rolls of the rolling mill are tilted so that the roll gap matches the cross-section of the entering workpiece.

[Brief explanation of the drawing]

The figure schematically shows a control system for a rolling mill. DESCRIPTION OF SYMBOLS 1... Rolling mill, 3... Housing, 5... Work roll, 7... Capsule-shaped fluid pressure cylinder, 9... Roll gap, 11... Converter, 13... Control circuit ,1
7... Scaler, 23... Differential amplifier.

Claims (4)

[Claims] (1) having a pair of housings, at least two rolls supported within the housing at opposite ends, and a pair of hydraulic cylinders, one associated with each howe step, to vary the roll gap; In a rolling mill control system, a pair of control circuits for controlling the operation of each cylinder, means for generating a signal representative of the load applied to each housing K, and providing an average value of said signals to each of said control circuits. and means for detecting a difference, if any, between the signals to produce a difference signal representing the difference, the difference signal being supplied to one of the control circuits, and having an amplitude equal to that of the difference signal. A control system characterized in that the load on the highest load housing is increased and the load on the lowest load housing is decreased by supplying signals of opposite polarity to the other control circuit. (2) The difference signal is supplied directly to one side of the control circuit and to the other side via a positive/negative converter.
Control system described in ). (3) The control system according to claim (2), wherein each of said circuits includes means for compensating for stention within the cylinder. (4) a pair of housings, at least two rolls supported within the housing at opposite ends, a pair of hydraulic cylinders associated with each housing to vary the roll gap; and a rolling mill. A rolling mill having a control system for controlling the operation of each cylinder, the control system comprising: a control circuit for controlling the operation of each cylinder; and means for generating a signal indicative of the load on the respective housing;
means for supplying an average value of the signals to the control circuit; and means for generating a difference signal representing the difference by determining a difference, if any, between the signals; and is configured to increase the load on the highest load housing and decrease the load on the lowest load housing by supplying a signal of equal amplitude and opposite polarity to the difference signal to the other control circuit. A rolling mill characterized by: