JPS6320117A - Meandering control method and device therefor - Google Patents

Abstract

PURPOSE:To perform stable meandering controls even in a tensionless condition at the time of runouts by changing a control gain into a smaller control gain for a tensionless condition when the rear end of a rolled stock runs out from an upstream rolling mill for tandem rolling. CONSTITUTION:A meandering amount deviation signal 23 is composed so as to be loaded with a control gain KPT in a normal tensile condition as well as a control gain KP smaller than the KPT by a regulator bodies 27, 28. When the rear end of a rolled stock runs out from an upstream rolling mill, changeover switches 25, 26 are changed by a runout signal 37. As a result, draft correction signals 32 and 33, for which the deviation signal 23 is loaded with the control gain KP in a tensionless condition smaller than the normal control gain KPT, adjust a roll gap to regulate meanderings. Therefore, an overgain is prevented even in a tensionless condition at the time of runouts to perform stable meandering controls.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method and apparatus for controlling meandering of a rolled material.

[Prior Art] In rolling operations, there is a phenomenon in which the rolled material cannot remain in the center of the rolls due to the conditions during rolling, and moves toward the ends of the rolls as the rolling progresses, as shown in Figure 7. It is well known and called serpentine.

Here, to briefly explain the meandering of the rolled material, the sixth
The figure shows a situation in which the rolled material a has shifted from the center of the work roll b to the right side for some reason. When it becomes as shown in Figure 6, the roll gap becomes uneven on the left and right sides, and the roll gap on the right side becomes uneven. The gap is wider than on the left. By the way, although the circumferential speed of work roll b is uniform on the left and right sides, the gap on the side is wider, so the volumetric flow rate of the rolled material per unit time is larger on the right side.

Also, if the thickness of the rolled material at the entry side is symmetrical,
The material will be drawn in faster on the side with a higher volumetric flow rate. As a result, as shown in Fig. 7, the rolled material a shifts to the right on the entry side (Ax) and cambers (Ax) on the exit side.
A y) occurs. Therefore, the difference between the left and right roll gaps becomes even larger, and the rolling 'vJa' approaches the right end more rapidly, resulting in a meandering phenomenon. At the same time, camber also increases.

In order to prevent such meandering and the accompanying camber,
It is effective to roll the material under conditions that create a convex crown. However, in recent years, as demands for improving the quality and yield of rolled materials have become stricter, it has become necessary to reduce convex crowns (rolling with a uniform thickness distribution in both the longitudinal and width directions). Under such conditions, the rolled material tends to meander, making stable operation difficult.

In recent years, as one of the means to prevent meandering, when a rolled material meanders, the force applied to the left and right load cells c and d (see Figure 6) changes, so this is detected and the meandering is known.
A method has been proposed to prevent this by moving a rolling device to narrow the roll gap on the side where the load increases.

However, with the above-mentioned means, there are problems such as the output change due to meandering and the output change due to operating the lowering device being mixed, the control system is unstable and tends to cause divergent vibration, and the accuracy is insufficient. The drawback is that it is completely impractical.

Therefore, in order to solve the above problems, the inventors of the present invention,
For example, a meandering control means as shown in Japanese Patent Application No. 58-65109 was proposed. The meandering control means includes detectors for detecting the width end position of the rolled material on the work side and the drive side on the entry side of the rolling machine, and calculates the amount of meandering by calculating the difference between the output signals of each detector. and a setting device for giving a target position of the rolled material, a device for comparing and calculating the output signal of the computing device and a target signal of the setting device, and a device for processing the signal obtained by the device and communicating with the work side. A meandering control adjustment device is provided which outputs a rolling reduction correction signal on the driving side, and the roll gap on the working side and the driving side is changed by the signal for the rolling reduction correction. That is, as can be seen from the meandering mechanism described above, the roll gap on the meandering side of the rolled material is closed and the opposite side is opened by the same amount.

[Problems to be Solved by the Invention] However, when the above-mentioned meandering control means is applied to a tandem rolling mill, during steady state (when tension is applied to the rolled material)
Through theoretical studies and actual machine tests, the inventor discovered that the meandering cannot be corrected unless the control gain of the meandering control adjustment device is increased several times the theoretical value when the tension is zero. Therefore, if the rolled material can be handled by a predetermined rolling mill in this state, there will be no tension in the rolled material, resulting in overgain and a phenomenon in which meandering control becomes unstable at the tail end of the rolled material. The control gain referred to here is a proportional coefficient that determines how many microns of the roll gap change command is output when the meandering distance is 1 mm.If this is increased, the amount of roll gap change per i mm meandering amount is increased. As it grows larger, control becomes more effective.

The above reason will be explained with reference to FIGS. 8 and 9. When tension is applied to the rolled material a, the side where the rolled material a meandered due to the meandering control (the drive side in FIGS. 8 and 9) When the roll gap is closed and the rolled material a is returned to the center position of the rolling mill, the material on the meandering side stretches, and there is a tension in the width direction of the rolled material a at the entrance side of the rolling mill as shown in Figure 9. A distribution occurs. That is, the rear tension stress on the side where the roll gap is closed is lower than the rear tension stress on the side where the roll gap is opened. This is equivalent to an increase in deformation resistance on the side where the upper roll gap is closed (
(because the tension has decreased), the pressure reaction force on the rolls increases and the roll gap widens. Therefore, the meandering control results in the effect of closing the gap being canceled. In this way, when tension is applied, the leveling effect by meandering control is canceled by tension feedback, so the control gain of the meandering control adjustment device must be set considerably large to strengthen the leveling effect. On the other hand, when the tension in the rolled material is zero, the leveling effect of meandering control is not canceled by the tension, so if the control gain is left as it is when tension is applied, meandering control becomes effective. This makes it difficult to perform stable meandering control.

Figures 10(A) and 10(D) show the amount of meandering when the tail end of the rolled material is pulled out of the rolling mill.Figure 10(A)
This is the case where meandering control is not performed, and the tail end of the rolled material loses tension and deviates to one side by Yl. In addition, Fig. 10 (b) shows the meandering control, which controls the deviation of the tail end of the rolled material to one side, but when the tension is zero, the proportional gain is too large, so the meandering control is too effective, causing a large overshoot. Rolled material is Y2 to both sides
, Y:i, and meandering control becomes unstable.

The present invention is based on the above-mentioned findings, and an object of the present invention is to enable stable meandering control in a downstream rolling mill even after the tail end of a rolled material passes through an upstream rolling mill during rolling by a tandem rolling mill. This is what was done.

[Means for Solving the Problems] The present invention provides a method for determining the meandering amount of a rolled material from the width end position of the rolled material on at least one of the input side and exit side of the required rolling mill in a tandem rolling mill. , determine the left and right rolling reduction correction signals based on the control gain from the difference between the meandering amount and the target position of the rolled material, adjust the required left and right roll gap of the rolling mill using the reduction correction signal, and control the meandering of the rolled material. When performing this, if the tail end of the rolled material passes through a rolling mill upstream of the required rolling mill, the gain used to obtain the reduction correction signal of the required rolling mill in accordance with the timing of the tail end of the rolled material is nullified. Meandering control is performed by changing the gain when tension is applied.

[Function] The amount of meandering of the rolled material is determined from the width end position of the rolled material detected by the detector, and the left and right rolling correction signals are determined from the difference between the amount of meandering and the target position of the rolled material based on the control gain. , the left and right roll gap is adjusted by the rolling correction signal to perform meandering control, and when the tail end of the rolled material passes through the upstream rolling mill, the above-mentioned control gain is set to zero tension in accordance with the timing of the tail end of the rolled material. The gain is lowered to the current value, and meandering control is continued.

[Example] Embodiments of the present invention will be described below with reference to the drawings.

1 to 3 show an embodiment of the present invention, in which 1a is an upstream rolling mill, 1b is a downstream rolling mill, and 1C is an upstream rolling mill 1.
2 is a load detector for detecting the rolling load of the upstream rolling mill 1a.

The downstream rolling mill 1b includes upper and lower work rolls 3 and 4, upper and lower backup rolls 5 and 6, lower back-up roll chocks 7 and 8 that support both shaft ends of the upper and lower backup rolls 5 and 6, and each lower back-up roll. roll chock 7.8
It is equipped with hydraulic cylinders 9 and 10 that act on rolling blades to roll the rolled material 11, and the amount of pressure oil flowing into and out of the left and right hydraulic cylinders 9 and 10 is controlled by a servo valve 13.
．． 14 and a displacement detector 15 for detecting the movement of the piston of the hydraulic cylinder 9.10.
16 are attached to the hydraulic cylinders 9, 10, and a summing amplifier 17.18 is provided for comparing the signal from the displacement detector 15.16 with the signal from the meander control regulator 24.

The left and right roll gaps are set by controlling the amount of pressure oil flowing into and out of the hydraulic cylinders 9 and 10 using servo valves 13 and 14, and fluctuations in the roll gaps are controlled by the pistons of the hydraulic cylinders 9 and 10. The movement is indirectly measured by displacement detectors 15, 16, and compared with the set signal by addition amplifier 17, 18. If there is a difference, the servo valve 13, 14 is corrected using the difference. do. Further, meandering amount detectors 19a and 19b are installed on the left and right sides of the entrance side of the downstream rolling mill 1b to detect the width end position of the rolled material 110 based on the light emitted from the rolled material 110, and signals from the respective detectors 19a and 19b are installed. The difference, that is, the amount of meandering of the rolled material 11, is determined by the calculator 20, and the amount of meandering is calculated by the setting device 2.
A comparator 22 performs a comparison with the target signal from 1, and the obtained meandering amount deviation signal 23 is processed by a meandering control regulator 24.

The meandering control regulator 24 turns on the changeover switch 25 which turns off the tail end of the rolled material detected by the load detector 2 of the upstream rolling mill 1a by a signal 29 and turns it off by the signal @37 of a timer 36. a changeover switch 26, and a regulator main body 27, 28 that applies a control gain KPT or 2 to the meandering amount deviation signal 23.
When both the rolling mill a and the downstream rolling mill 1b are engaged, the signal output from the regulator main body 27 is added to the addition amplifier 17, 18 as the left and right rolling reduction correction signals 30, 31 so that 1q is applied. When the tail end of the rolled material 11 leaves the upstream rolling mill 1a, the signal output from the regulator main body 28 can be applied to the addition amplifier 17.18 as the left and right rolling reduction correction signals 32.33. do.

In addition, the output of the regulator 24 is, for example, in a direction in which when the rolled material 11 moves toward the working side, the roll gap on the working side is tightened and the roll gap on the driving side is listened to, or in a direction in which the rolled material 11 is If it approaches the side, the direction is determined so that the [1-le gap control is performed, contrary to the above, and the addition amplifier 17.
It is now possible to add 18.

During steady state, when the rolled material 11 is bitten by both the upstream rolling mill 1a and the downstream rolling mill 1b and tension is applied to the rolled material 11 on the inlet side of the downstream rolling mill 1b, the load of the upstream rolling mill 1a From the detector 2, there is a meandering control regulator 2 of the downstream rolling mill 1b.
4, the ash removal signal is not given. Therefore, in the meandering control regulator 24 of the downstream rolling mill 1b, the changeover switch 25 is
is turned on and the selector switch 26 is turned off.

The computing unit 20 calculates the meandering amount from the width end position of the rolled material 11 detected by the meandering amount detectors 19a and 19b, and the comparator 22 compares the meandering amount with the target value of the rolled material from the setting device 21. A meandering amount deviation is determined by comparison calculation, and the meandering amount detector @23 outputted from the comparison calculator 22 is given to the meandering control regulator 24, and via the changeover switch 25, the controller body 27 sets the control gain KPT. It is applied to the summing amplifier 17.18 as a reduction correction signal 30.31. Therefore, in the addition amplifier 17.18, the actual displacement signal of the screws 1 to 1 of the hydraulic cylinders 9, 10 is combined with the reduction correction signal. After the comparison is made, the servo valves 13 and 14 control the amount of pressure oil flowing into and out of the hydraulic cylinders 9 and 10 based on the difference signal.
As a result, the left and right roll gaps are changed, the meandering is prevented from further progressing by the mechanism described above, and the rolled material 11 is returned to the target value given by the setter 21.

When the tail end of the rolled material 11 is removed from the upstream rolling mill 1a, an ash removal signal 29 is activated from the load detector 2 of the upstream rolling mill 1a to the meandering control regulator 24 of the downstream rolling mill 1b. A signal 37 from a timer 36 is applied to turn off the changeover switch 25 and turn on the changeover switch 26. Therefore, the meandering amount deviation signal 23 from the comparator 22 passes through the changeover switch 26 to the controller body. 28
is multiplied by a control gain smaller than the control gain KPT, and the reduction correction signal is applied as signals 32 and 33 to the summing amplifiers 17 and 18, and meandering control is performed in the same manner as described above. In the example shown in FIG. 5 (a) middle), 1
This is the same time as when it is changed to ``crab''.

By the way, the hydraulic cylinders 10, 9 and the displacement detector 16°1
5. Since the rolling device composed of servo valves 14 and 13 has a response delay, even if the control gain KPT is changed to KP at the same time as the tail end of the rolled material 11 passes through the rolling mill 1C, the left and right roll gap does not change immediately, and it is difficult to correct the overgain condition. To solve this problem, the timer 36 is connected to the signal 37 from the timer 36.
However, it is preferable to set the rolling mill 1C so that the tail end of the rolled material 11 is outputted a little before it breaks.

FIG. 4 shows another example of the meandering control regulator 24 used in the present invention, in which the meandering amount deviation signal 23 from the comparator 22 of FIG.
can be added to the regulator body 27, and the regulator body 27
The output from the function generator 35 can be applied to the multiplier 34, and the output signal from the function generator 35 can be applied to the multiplier 34 via the changeover switch 26.

When tension is applied to the rolled material 11 on the inlet side of the downstream rolling Bib, the changeover switch 26 is turned off, so the meandering amount deviation signal 23 is multiplied by the control gain KPT by the regulator main body 27. It is output as a reduction correction signal through a multiplier 34, but when the drag plate at the tail end of the rolled material 11 receives a signal 37 from a timer 36 started by a signal 29 from a load detector of the upstream rolling mill, it activates the changeover switch 26. is turned on, the function generator 35 outputs a proportionality coefficient K that decreases over time and reaches a constant value after a certain period of time, the maximum value of which is smaller than 1, and is applied to the changeover switch 26h1 to the multiplier 34, and the The meandering amount deviation signal multiplied by the control gain KPT in the main body 27 is multiplied by the proportional coefficient K from the function generator 35 in the multiplier 34, and the result is output as a reduction correction signal. In this case, the control gain KP when no tension is applied to the tail end side of the rolled material is represented by □, = □, and □, which is illustrated in FIG. 5(c).

In the embodiment of the present invention, a case has been described in which the target position of the rolled material is given by the setting device 21, but it is also possible to memorize the initial biting position of the rolled material 11 into the rolling mill and give it as the control target. Or, it can be carried out by freely changing the setting so that the rolled material 11 passes through any position in the width direction of the rolled material, and if the rolled material is a cold rolled material, a light source is installed above or below the rolled material. Therefore, the present invention can be applied not only to four-high rolling mills but also to all types of rolling mills where meandering is a problem, the control circuit can be configured with software using a computer instead of hardware, and the amount of meandering It is also possible to attach detectors to both the inlet and outlet sides of the rolling mill and configure the control device of the present invention based on the signals from both sides, within the scope of the invention. Of course, various changes may be made.

[Effect of the Invention 1] According to the meandering control method and its device of the present invention, an excellent effect can be achieved in that stable meandering control can be performed even when the rolled material is under no tension.

[Brief explanation of the drawing]

Figures 1 to 3 are explanatory diagrams of one embodiment of the present invention, in which Figure 1 is an explanatory diagram of meandering control in steady state, Figure 2 is an explanatory diagram of meandering control in no tension, and Figure 3 is an explanatory diagram of meandering control in the absence of tension. A detailed view of the meandering control device, FIG. 4 is an explanatory diagram of another example of the meandering control regulator used in the present invention,
Figure 5 (A) is a graph showing the state in which the tail end of the rolled material changes from a state in which tension is applied to a state in which no tension is applied, and Figure 5 (O) (
c) is a graph showing the control gain when changing from a state where tension is applied to no tension as shown in Fig. 5 (a);
Fig. 6 is an explanatory diagram of the case where the rolled material snakes toward one end of the roll, Fig. 7 is a plan view of Fig. 6, and Figs. 8 and 9 are explanatory diagrams of the reason for reducing the control gain when no tension is applied. , Fig. 10 (a) is an explanatory drawing of meandering when the tail end of the rolled material is tensionless without meandering control, and Fig. 10 (0) is an illustration of the meandering when the tail end of the rolled material is under no tension when meandering control is performed. It is an explanatory view of meandering when the end becomes tensionless. In the figure, 1a is an upstream rolling mill, 1b is a downstream rolling mill, 1C is a rolling mill between 1a and 1b, 2 is a load detector, 9°10 is a hydraulic cylinder, 13.14 is a servo valve, 15.16 17.18 is a displacement detector, 17.18 is an addition amplifier, 19a and 19b are meandering amount detectors, 20 is an arithmetic unit, 21 is a setting device, 22 is a comparator, 24 is a meandering control regulator, and 25.26 is a changeover switch. , 27.28 is the regulator body, 34 is the multiplier, 3
5 indicates a function generator. Taste princess-υ

Claims (1)

[Claims] 1) In a tandem rolling mill, the amount of meandering of the rolled material is determined from the position of the width end of the rolled material on at least one of the input side and exit side of the required rolling mill, and the meandering amount and the rolled material are determined. The left and right roll correction signals are determined based on the control gain from the difference between the target position and the target position, and the left and right roll gaps of the rolling mill are adjusted according to the reduction correction signals. When the end passes through a rolling mill upstream of the required rolling mill, change the gain for obtaining the rolling reduction correction signal of the required rolling mill to the gain when no tension is applied at least by the time the end passes through the rolling mill. A meandering control method characterized in that meandering control is performed by: 2) A detector for detecting the position of the width end of the rolled material, which is installed on the working side or the drive side of at least one of the entry side and exit side of the required rolling mill in the tandem rolling mill, and the output of the detector. A meandering amount calculation device that calculates a meandering amount by calculating a difference between signals, a comparison calculation device that compares and calculates an output signal of the meandering amount calculation device and a target position signal of the rolled material, and a signal obtained by the comparison calculation device. The rolling correction signal for the work side and drive side is determined and output from the machine, and the rolled material passes through the upstream rolling mill.
A meandering control adjustment device is provided which is capable of changing the control gain of the meandering control to the set value at the time of no tension at least by that point, and the roll gap on the working side and the driving side is changed by the reduction correction signal. A meandering control device characterized by: