JPH02307613A - End drop control method for plate rolling - Google Patents

Abstract

PURPOSE:To decrease the number of times of shift of a work roll and to prevent the damage of a bearing part by deriving a difference of a detection value and a target value of the edge drop quantity and accumulating it successively, and correcting the work roll shift quantity, when the accumulated value exceeds a threshold limit value set in advance. CONSTITUTION:An X-ray plate crown meter 6 for detecting the edge drop quantity of a steel plate S is placed in the delivery of a rolling mill 1, and a detecting signal of the X-ray plate crown meter 6 is sent to an arithmetic unit 7. The arithmetic unit 7 derives a difference of the edge drop quantity and the target edge drop quantity, and subsequently, derives an evaluation function by accumulating successively the difference. Next, the evaluation function and an accumulated edge drop threshold limit value are compared, and based on an expression, whether the work roll shift quantity is corrected or not is judged. In the case the correction is required, the correction quantity is operated by the expression. The correction is outputted to a work roll shift 5 through a controller 8, and based on the correction quantity, a work roll 2 is shifted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of application in the FFI industry] This invention relates to an edge drop control method in plate rolling.

This invention is utilized for hot, warm or cold rolling of metal plates such as steel.

[Prior art] The plate thickness distribution (plate crown) in the width direction of a rolled plate is one of the important qualities of rolled products, and a flat or medium-high plate shape without edge drops is desired. . Requirements for such a plate shape are becoming stricter year by year.

As a rolling method for preventing edge drops, for example, the "shape control rolling method" disclosed in Japanese Patent Publication No. 60-51921 is known. This shape control rolling method is
A pair of work rolls each having a crown including a tapered grinding area at one end of a rolling roll cylinder are stacked vertically in an alternating arrangement at one end and are movable in the roll axis direction. Then, when performing rolling, the upper and lower work rolls are moved according to the width of the plate to be rolled, and both edges of the plate to be rolled are located in the tapered grinding areas of the upper and lower work rolls, respectively. Thereby, the contact pressure between the work roll and both edges of the rolled plate can be reduced, and rapid changes in roll flattening deformation at both edges can be alleviated. As a result, there is no peculiar metal flow at both edges, making it possible to effectively prevent the occurrence of edge drops.

[Problems to be Solved by the Invention] In conventional edge drop feedback control, the work roll shift is operated based on the difference between the edge drop amount detected on the exit side of the rolling mill and a target value. On the other hand, the edge drop amount, and therefore the above-mentioned difference, frequently fluctuates in the longitudinal direction of the plate. As a result, work roles traditionally had to be shifted frequently. Since the work rolls are shifted while a rolling load is applied to the work rolls, there is a problem in that if the work rolls are shifted frequently, the bearings of the work rolls will wear out and be damaged.

The present invention aims to provide a method for controlling tool drop in plate rolling without damaging the bearings of work rolls.

[Means for solving the problem] The edge drop control method in plate rolling of the present invention includes:
In rolling in which edge drop of a plate is controlled by shifting a work roll with a tapered roll body end in the width direction of the plate, the amount of edge drop is periodically detected on the exit side of the rolling mill. Then, the difference between the edge drop amount detected for each detection and the target edge drop amount and the target edge drop amount is sequentially accumulated, and when the cumulative value exceeds a preset limit value, the work roll shift amount is corrected.

This invention will be explained in more detail below.

The edge drop scale is generally expressed by the following equation (1).

D=hso h+s ''(1) Here, as shown in Figure 3, h, 5 is 15mm from the plate edge.
hso represents the thickness at a position 50+nm from the edge of the plate.

The edge drop amount D (kT) is detected at every sampling period T by a well-known X-ray or γ-ray plate crown meter placed on the exit side of the rolling mill (k·0, 1, 2, . . . ).

Although it varies depending on the rolling conditions and the dimensional accuracy required for the product, the sampling period T is, for example, 0.5 to 3' se
It is about c.

Edge drop amount D (k
T) and target edge drop scale. Difference ΔD (kT)
= D (kT) −D, −(2) is determined. Next, the evaluation function J is obtained by sequentially accumulating the differences ΔD (kT).

J = Hair ΔD (KT) ... (3)
k, 1 Next, the evaluation function J and the cumulative edge drop limit value J set in advance for each sampling. Compare with and make the following judgment.

If J>Jo, The amount of work roll shift is not modified.

Cumulative edge drop limit value J. is determined to a value such that the number of work roll shifts is, for example, several times per coil. Although it varies depending on the rolling conditions and the dimensional accuracy required for the product, the cumulative edge drop limit value J. is about 2 to 20 times the target edge drop measurement, l.

When correcting the work roll shift l-amount, the correction amount Δδ8
is determined by the following equations (5) and (6).

ΔδW=AΔF (6) Here, A is an influence coefficient. The influence coefficient A is determined in advance by experiment with an actual machine or by numerical calculation.

The above calculation is performed by, for example, a control computer. The calculation result is manually input to the controller, and the controller outputs the operation amount, that is, the correction amount ΔδW to the work roll shift.

[Operation] Work roll shift is activated only when the cumulative value of the difference between the detected edge drop amount and the target value exceeds a preset value. Therefore, compared to the case where the work roll shift is operated based on the difference between the detected edge drop amount and the target value, the number of work roll shifts is significantly reduced.

[Example] Cold rolling of a steel plate using a 6111 rolling mill will be described as an example.

FIG. 1 shows an example of a rolling mill embodying the present invention, and FIG. 2 shows the configuration of the rolling rolls of the rolling mill.

As shown in these drawings, the rolling mill 1 includes work rolls 2,
61 consisting of intermediate roll 3 and backup roll 4
It is a 1i rolling mill. The work roll 2 has a tapered end 2a at one end of the roll body, and is also provided with a work roll shift 5. The work roll shift 5 includes a hydraulic cylinder (not shown) and displaces the work roll 2 in the roll axis direction. The diameter and roll body length of each roll are: Work roll: φ 350 x 2020 mm
, intermediate roll: φ 600 x 2020 mm, backup roll: φ 1300 x 2020 mm.

An X-ray plate crown meter 6 for detecting the edge drop amount of the steel sheet S is arranged on the exit side of the rolling mill 1.

A detection signal from the X-ray plate crown meter 6 is sent to a calculation device 7. The calculation device 7 calculates the difference ΔD (kT) between the edge drop amount D (kT) and the target edge drop N Do,
Then, the evaluation function J is obtained by sequentially accumulating the differences ΔD (kT). Then, the evaluation function J and the cumulative edge drop limit value J. It is determined whether or not to correct the work roll shift amount based on equation (4). If correction is required, the correction amount Δδ is calculated using equations (5) and (6) above.
Calculate the value. The correction amount Δδ8 is output to the work roll shift 5 via the controller 8, and the work roll 2 is shifted based on the correction amount Δδ0.

A steel plate (plate thickness: 2.7 mm, plate width: 1200 mm) was cold rolled to a plate thickness of 1 and ε19 mm using the above rolling mill. The rolling conditions are as follows.

Reduction rate: 30* Front tension rolling σ, = 13kg/mm2 Rear force rolling length σh = 3kg/mm2 Target edge drop amount Do: 59m Sunblink period: 2sec Cumulative edge drop limit value: 10μm As a result of the above rolling, the conventional method The number of work roll shifts has been reduced to approximately 15 compared to the previous model. Furthermore, the amount of edge drop could be suppressed to approximately 5 IJm or less.

[Effects of the Invention] According to the present invention, the number of shifts of the work roll can be significantly reduced, so damage to the work roll bearing can be prevented.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an apparatus showing an example of a rolling mill implementing the present invention, FIG. 2 is a front view showing the configuration of the rolling rolls of the rolling mill shown in FIG. 1, and FIG. 3 is an explanatory diagram of an edge drop. It is. DESCRIPTION OF SYMBOLS 1... Rolling mill, 2... Work roll, 2a... Taper part of work roll, 3... Intermediate roll, 4...
Backup roll, 5...Work roll shift, 6
. . . Plate crown meter, 7. Arithmetic device, 8. Controller, S. Steel plate.

Claims (1)

[Claims] 1. In rolling where the edge drop of the plate is controlled by shifting a work roll with a tapered roll body end in the width direction of the plate, the amount of edge drop is periodically detected on the exit side of the rolling mill, and the amount of edge drop is periodically detected. In plate rolling, the difference between the detected edge drop amount and the target edge drop amount is determined and accumulated sequentially, and when the cumulative value exceeds a preset limit value, the work roll shift amount is corrected. Edge drop control method.