JPH04266414A - Device for controlling meandering in rolling - Google Patents

Abstract

PURPOSE:To surely prevent error of control and deterioration of accuracy from generating due to disturbance to detected load difference that is used for control regarding a device for controlling meandering of strip when rolling sheet with a hot strip mill or cold strip mill. CONSTITUTION:This device is characterized by that means 26 for detecting meandering which are provided on the inlet side and/or outlet side of the rolling mill and with which meandering of a strip 2 is detected and a logic switch 28 with which control output to rolling mill is turned to 'on' in the case the control direction of the roll gap of rolling mill doesn't conflict with the mendering direction of strip that is detected with the means 26 for detecting meandering and, contrarily, the control output to the rolling mill is turned to 'off' in the case the control direction of the roll gap of rolling mill is conflicts with the meandering direction of strip that is detected with the means 26 for detecting meandering are provided.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a strip meandering control device during rolling of a strip using a hot strip mill or a cold strip mill.

0002

[Prior Art] In general, strip meandering prevention technology is used to prevent misrolls caused by bumping against rolling mill housings or side guides, to prevent roll flaws caused by squeezing, and to prevent trimming troubles and yield declines in post-processes. Therefore, it is a very important technology.

[0003] As a control means for preventing such meandering, for example, as disclosed in Japanese Patent Publication No. 63-32525, the load difference between the left and right sides of the rolling mill due to meandering is detected, and the control means is controlled according to the load difference. Means for controlling the left and right roll gaps are known.

FIGS. 4 and 5 are a sectional view and a plan view, respectively, for explaining the meandering phenomenon. When meandering occurs in the strip 2, the balance of the moment of the rolling reaction force acting on the rolling mill is lost, and the rolling load PW (>PD) on the side where the strip 2 meanders (the left side in FIGS. 4 and 5) increases. . Therefore, in principle, meandering control is performed by tightening the roll gap on the side where the load is higher in accordance with the left and right rolling load difference ΔP (=PW-PD) generated in this way.

In FIGS. 4 and 5, 1 is the work roll, PW is the work side rolling load, PD is the drive side rolling load, hW is the work side plate thickness, hD is the drive side plate thickness, and Δh is the exit side plate. Thick wedge (=hW-h
D), W is the plate width of the strip 2, and Δθ is the rotation angle of the strip 2 on the entry side.

[0006]

[Problems to be Solved by the Invention] However, in the conventional meandering control means during plate rolling, when there is a wedge (difference in plate thickness in the width direction) in the entrance side plate thickness as shown in FIG. At the same time as the load on the side increases, the strip 2 tries to meander toward the thinner side, but as a control, it operates to tighten the roll gap on the thicker side of the plate where the load is higher. This will cause malfunctions, and as shown in FIG. 5, this will actually encourage meandering.

Therefore, in severe cases, the strip 2 may protrude beyond the work roll 1, or the strip 2 may
As a result, the strip 2 and the work roll 1 are damaged, resulting in large economic losses such as having to discard the product and replacing the roll.

Furthermore, even if squeezing does not occur, control in the correct direction will not start until the meandering progresses and the direction in which the load difference occurs is reversed, and additional rolls will occur due to the malfunction. Since the gap must be changed, the control delay increases, resulting in a significant loss of overall control effectiveness and control stability.

[0009] Here, the control operation and problems of the conventional means will be explained with reference to the control block diagram of the conventional means shown in FIG. In FIG. 6, 21 is a meandering phenomenon part that models the meandering phenomenon of the strip 2, 22 is a differential load generation part that models the generation of left-right load difference ΔP in the rolling mill, and 23 is a part that corresponds to the left-right load difference ΔP in the rolling mill. A meandering control calculation unit 24 that performs control calculations for tightening the roll gap on the side where the load is higher is a hydraulic pressure reduction system that operates in response to the control output ΔSC from the meandering control calculation unit 5.

[0010] Also, ΔS0 is the initial leveling deviation amount, Δ
S is the leveling change amount, ΔST is the leveling change amount, Δ
h is the exit side thickness wedge amount, ΔH is the entrance side thickness wedge amount,
h is the exit side plate thickness, H is the input side plate thickness, r is the rolling reduction rate, Δr is the difference in the left and right rolling reductions, vR is the circumferential speed of the work roll 1, Δθ is the rotation angle of the strip 2 on the input side, W is the board of the strip 2 Width, vi
is the input side speed, Δy0 is the meandering amount of the strip 2 on the input side, Δ
y is the meandering amount of the strip 2 directly under the work roll 1, ΔP
is the left and right load difference, ΔSC is the leveling change command value, ∂Δ
h/∂ΔS is the influence coefficient of ΔST on Δh, ∂Δh/
∂ΔH is the influence coefficient of ΔH on Δh, ∂ΔP/∂Δy
is the influence coefficient of Δy on ΔP, ∂ΔP/∂ΔH is ΔH
The influence coefficient on ΔP, ∂ΔP/∂ΔS, is the influence coefficient of ΔST on ΔP.
The influence coefficient on P, ∂Δh/∂Δy, is the influence coefficient of Δy on Δh.

As shown in the differential load generating section 22, the load difference Δ
P can be described using the meandering amount Δy, the entrance side plate thickness wedge ΔH, and the leveling change amount ΔST as shown in the following equation (1).

0012

[Math 1]

Therefore, the load difference ΔP is not caused only by meandering, but is also greatly influenced by the entry side plate thickness wedge ΔH and the leveling change amount ΔS for meandering control.

However, regarding the influence of ΔS, since the control amount ΔSC is known in advance, ΔPSC=(∂ΔP/∂ΔS)C
・ΔSC (
2) Using the following relationship, it is relatively easy to cancel the load difference ΔP due to leveling change by ΔPSC.

However, it is practically very difficult to accurately predict ΔH unless an actual value is obtained using a wedge meter or the like, and an error in ΔP due to ΔH is difficult to avoid using conventional control means.

The conventional control means and its operation will be explained in more detail with reference to FIGS. 7 and 8. Here, a case is shown in which the conventional means is applied to the F7 stand of a hot tandem rolling mill.

In FIG. 7, 3 is a backup roll;
4 and 5 are rolling cylinders that apply loads to both ends of the backup roll 3 to adjust the rolling position, and 6 and 7 are rolling positions Sw on the work side and drive side, respectively.
8 and 9 are load cells that detect the rolling loads Pw and Pd on the work side and the drive side, respectively. 10 and 11 are amplifiers 12 and 1, respectively.
Hydraulic servo which receives the command value from 3 and operates the reduction cylinders 4 and 5, and 14 and 15 are the reduction position detectors 6, respectively.
, 7, a computer that calculates a control command value for each of the cylinders 4 and 5 in response to the reduction command value SC0 and the output from a comparator 20 (to be described later); 16 is a drive side computer; A rolling position deviation calculator for calculating the difference Sdf between the rolling position Sd and the rolling position Sw on the work side, 17
18 is a load difference calculator that calculates the difference Pdf between the work side rolling load Pw and the drive side rolling load Pd, and 18 is a load difference calculator that calculates and outputs the leveling change amount based on the difference output Pdf from the load difference calculator 17. A leveling change output calculation unit 19 is a gain multiplier that multiplies the output from this leveling change output calculation unit 18 by a predetermined gain; 20 is a leveling change amount obtained by this gain multiplier 19 and a reduction position deviation calculation unit 16; A comparator 25 is a hydraulic pressure reduction control device which calculates the deviation from the difference output Sdf and outputs it to the calculators 14 and 15.

With this configuration, meandering control is performed by tightening the roll gap on the side where the load is higher according to the difference in rolling load Pdf between the left and right sides. As shown, although strip 2 snakes toward the work side at the entrance side of the F7 stand, the leveling control output is initially an output that tightens the drive side, and at the exit side of the F7 stand, the leveling control output is an output that tightens the drive side. The meandering progresses even more rapidly. As a result, the leveling control output is finally reversed to the original work side tightening side, but the control timing is too late and rolling is completed while the meandering on the exit side of the F7 stand remains large. In the example shown here, fortunately, no troubles such as narrowing have occurred, but the meandering has reached the point where it is on the verge of trouble.

The present invention aims to solve these problems, and provides a meandering control device during plate rolling that can reliably prevent control errors and deterioration of accuracy due to disturbances to the detected load difference used for control. The purpose is to

[0020]

[Means for Solving the Problems] In order to achieve the above object, the meandering control device during strip rolling of the present invention is provided with: a detecting means; (i) when the control direction of the roll gap in the rolling mill is consistent with the strip meandering direction detected by the meandering detecting means, the control output to the rolling mill is turned on; The rolling mill is characterized by comprising a logic switch that turns off the control output to the rolling mill when the control direction of the roll gap in the rolling machine is inconsistent with the strip meandering direction detected by the meandering detection means. .

[0021]

[Operation] In the above-mentioned meandering control device during plate rolling of the present invention, when the control direction of the roll gap is consistent with the detected meandering direction, for example, a control command to tighten the rolling on the right side of the rolling mill is output. At the same time, when the strip is meandering toward the right side of the rolling mill with respect to its neutral threading position, the control output is turned on by the logic switch.

On the other hand, if the control direction of the roll gap is inconsistent with the detected meandering direction, for example, even though a control command to tighten the rolling on the right side of the rolling mill has been output, the strip will not move through that direction. When the rolling mill is meandering toward the left side with respect to the plate neutral position, the control output is turned off by the logic switch.

[0023]

[Embodiment] A meandering control device during plate rolling as an embodiment of the present invention will be explained below with reference to the drawings. Fig. 1 is a circuit diagram showing a meandering control device as an embodiment of the present invention, and Fig. 2 is a circuit diagram showing the meandering control device as an embodiment of the present invention. It is a control block diagram of an embodiment, and in the drawing, the same reference numerals as those already described indicate the same parts, and therefore the explanation thereof will be omitted.

In FIGS. 1 and 2, reference numeral 26 indicates a meandering detector (meandering detection means) provided on the inlet side and/or outlet side of the rolling mill to detect meandering of the strip 2; A roll gap tightening direction determination circuit 28 receives the detection result and the leveling control output from the comparator 20 and determines whether or not the meandering direction and the leveling change direction match. This logic switch 28 is a logic switch that is turned on and off according to the determination result by the determination circuit 27. This logic switch 28 receives the determination result by the roll gap tightening direction determination circuit 27,
When the control direction of the roll gap in the rolling mill does not contradict the strip meandering direction detected by the meandering detector 26 (when the meandering generation direction and the leveling change direction match), the hydraulic reduction control device 25 (rolling mill ) is driven to turn on the control output of the rolling mill, and if the control direction of the roll gap in the rolling mill is inconsistent with the strip meandering direction detected by the meandering detector 26 (the meandering direction and leveling change (if the direction does not match)
At this time, the control output to the hydraulic rolling control device 25 (rolling mill) is turned off.

With the above configuration, when the control direction of the roll gap is consistent with the detected meandering direction, that is, for example, a control command to tighten the rolling on the right side of the rolling mill has been output, and the strip 2 is When the roll gap tightening direction determining circuit 27 determines that the meandering direction matches the leveling change direction, the logic switch 28 is turned on. , the leveling control output from the comparator 20 is input to the hydraulic pressure reduction control device 25.

On the other hand, if the control direction of the roll gap is inconsistent with the detected meandering direction, for example, even though a control command to tighten the roll on the right side of the rolling mill has been output, the strip will not move through that direction. When the strip is meandering toward the left side of the rolling mill with respect to the neutral position of the plate, and the roll gap tightening direction determining circuit 27 determines that the meandering direction and the leveling change direction do not match, the logic switch 28 is turned off. The leveling control output from the comparator 20 is not input to the hydraulic pressure reduction control device 25.

[0027] Therefore, the above-described erroneous control in which the meandering direction and the leveling operation direction are inconsistent with each other in the conventional example is eliminated, and extremely stable meandering control can be realized.

FIG. 3 shows the operation of the apparatus of this embodiment. As shown in FIG. 3, the meandering control starts to take effect at the timing when the entry meandering direction and the leveling control direction do not conflict, and as a result, the amount of meandering on the exit side of the F7 stand is controlled to an extremely small range. I understand.

In the above embodiment, the case where the apparatus of the present invention is applied to the F7 stand of a hot tandem rolling mill has been described, but the present invention is not limited thereto.

[0030]

As described in detail above, according to the meandering control device during strip rolling of the present invention, when the control direction of the roll gap in the rolling mill is consistent with the strip meandering direction detected by the meandering detection means, In this case, the control output to the rolling mill is set to "ON", and when the control direction of the roll gap in the rolling mill is inconsistent with the strip meandering direction detected by the meandering detection means, the control output to the rolling mill is set to "ON". Since the structure is configured such that the meandering direction is turned off, erroneous control where the meandering direction and the leveling operation direction contradict each other is eliminated, and extremely stable meandering control can be realized.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a meandering control device as an embodiment of the present invention.

FIG. 2 is a control block diagram of this embodiment.

FIG. 3 is a timing chart for explaining the operation of this embodiment.

FIG. 4 is a cross-sectional view for explaining the meandering phenomenon of the strip.

FIG. 5 is a plan view for explaining the meandering phenomenon of the strip.

FIG. 6 is a control block diagram using conventional means.

FIG. 7 is a circuit diagram showing an example of conventional means.

FIG. 8 is a timing chart for explaining the operation of conventional means.

[Explanation of symbols]

1 Work roll 2 Strip 3 Backup roll 4, 5 Reduction cylinder 6, 7 Reduction position detector 8, 9 Load cell 10, 11 Hydraulic servo 12, 13 Amplifier 14, 15 Calculator 16 Reduction position deviation calculator 17 Load difference calculator 18 Leveling change output calculator 19 Gain multiplier 20 Comparison calculator 21 Meandering phenomenon section 22 Differential load generation section 23 Meandering control calculation section 24 Hydraulic reduction system 25 Hydraulic reduction control device 26 Meandering detector (meandering detection means) 27
Roll gap tightening direction determination circuit 28 logic switch

Claims (1)

[Claims] 1. A meandering control device during plate rolling that controls the meandering of a strip using a load difference between left and right sides of a rolling mill, wherein the meandering control device is provided on the entry side and/or exit side of the rolling mill to detect the meandering of the strip. If the meandering detection means and the control direction of the roll gap in the rolling mill do not conflict with the strip meandering direction detected by the meandering detection means, the control output to the rolling mill is set to "on", while the rolling A logic switch is provided that turns off the control output to the rolling mill when the control direction of the roll gap in the rolling machine is inconsistent with the strip meandering direction detected by the meandering detection means. Meandering control device during plate rolling.