JP2659056B2 - Rolling force control method in temper rolling of steel strip - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling rolling force in temper rolling of a steel strip (hereinafter referred to as "strip").

[0002]

2. Description of the Related Art Generally, in a temper rolling mill, ear extension,
It is necessary to keep the strip shape such as belly stretch and cross buckle (bellows) and the plate surface roughness within a certain level. In this case, regarding ear growth and belly growth, crown control by a bender is common. Regarding the cross buckle, the buckling phenomenon in the width direction of the roll bite is the main cause, and thus it is generally adjusted by the output side tension of the rolling mill or the final stand rolling force. The surface roughness is adjusted by the final stand rolling force.

Here, the size of the cross buckle means a peak value obtained from a cross-sectional profile in the width direction when the sample is left standing on a horizontal plane, or (peak value) / (pitch between waves). As for the cross-sectional profile in the width direction, as shown in FIG. 6, it is generally used to move the stylus 11 in contact with the strip 1 in the width direction and to stack the stylus 11 from the vertical deviation of the stylus. The same method is generally used for the plate surface roughness.

By the way, many temper rolling mills are batch-type mills, and the line speed must be reduced at the leading and trailing ends of the coil. In addition, even in an in-line temper rolling mill of a continuous annealing path, it is general to install a looper on the inlet side of the temper rolling mill so as not to change the line speed in the annealing furnace during work roll change of the rolling mill. For this reason, the line speed in the temper rolling mill must be reduced at the leading end and the trailing end.

[0005] Here, since the strain rate is different between the high-speed part and the low-speed part, ear growth, belly expansion, cross buckle, and plate surface roughness change, leading to a problem of quality deterioration or yield reduction. At this time, the difference in the steepness in the width direction such as ear extension and belly extension is determined by adjusting the roll crown in accordance with the rolling speed, as disclosed in Japanese Patent Application Laid-Open No. Sho 62-230410. There is known a method for achieving the above.

[0006]

However, the method of adjusting the roll crown corresponding to the above-mentioned rolling speed has a problem that the size of the cross buckle and the surface roughness cannot be adjusted. An object of the present invention is to provide a method of controlling a rolling force in a temper rolling mill that can stabilize the size of a cross buckle and the surface roughness of a strip in temper rolling over the entire length of a strip.

[0007]

According to the present invention, in temper rolling of a steel strip, an appropriate rolling force is determined in advance in a final stand for keeping the size of a cross buckle constant in accordance with a rolling speed. A rolling force control method in temper rolling of a steel strip, wherein the final stand is lowered by a force.

[0008]

[Operation] The present inventors have conducted various investigations and found that the size (peak value) / (wave pitch) of the cross buckle was higher as the final stand rolling force was higher and the rolling speed was higher as shown in FIG. I found that the larger the later, the larger. Further, as shown in FIG. 2, it was found that the transfer rate of the roll roughness to the plate surface increased as the final stand rolling force was higher and the rolling speed was lower.

Therefore, according to the present invention, a target value for the size of the cross buckle is set, and an appropriate rolling force at each rolling speed is determined so as to reach the target value. Since the rolling force is controlled to the appropriate value for the cross buckle, the size of the cross buckle becomes constant over the entire length of the coil, and the plate surface roughness can be closer to the target value compared to a case where the rolling force control is not performed. .

[0010]

An embodiment of the present invention will be described with reference to the drawings. FIG. 3 is a graph in which an appropriate rolling force for keeping the size of the cross buckle constant according to the rolling speed is obtained in advance. As can be seen from FIG. 3, at a low rolling speed, the appropriate rolling force has a small value, so that the final stand is rolled with the proper rolling force to bring the surface roughness closer to a constant value. There is also an effect.

In the conventional method, as shown in FIG. 5, the size of the cross buckle and the plate surface roughness deviated from the target values in the low-speed rolling section. However, in the present invention, the rolling force is controlled in accordance with the rolling speed by the appropriate rolling force in which the cross buckle is made constant in accordance with the rolling speed in FIG. Good results were obtained in which the roughness was all within the target value over the entire length of the coil.

FIG. 5 is a block diagram of an embodiment of an apparatus suitable for implementing the method of the present invention. 1 in FIG.
Is a strip which is a temper rolled material, 2 is a two-stand tandem temper rolling mill, 2a and 2a 'are work rolls thereof,
The rolling mill is provided with a speed detector 3 and a rolling force detector 8.

The adjustment of the rolling force for the temper rolling to make the surface roughness of the strip 1 uniform over the entire area is performed by converting the speed signal detected by the speed detector 3 connected to the No. 2 stand work roll 2 into a signal. Is converted by the container 4. Then, a signal related to the speed, a material condition of the strip 1 and a rolling force signal sent from the rolling force detector 8 through the rolling force signal converter 9, and a signal input by the cross buckle target value setting input means 10. In consideration of the above, the storage operation device 5 calculates an appropriate rolling force according to the relationship shown in FIG. 3, and amplifies the output by the amplifying device 6 and outputs the amplified output to the rolling force control mechanism 7 to obtain a predetermined rolling force. I do.

[0014]

As described above, according to the present invention, since the rolling force is controlled in accordance with the rolling speed so that the size of the cross buckle is constant, the size of the cross buckle is made uniform over the entire length of the coil. it can. It also has the effect of reducing variations in plate surface roughness.

[Brief description of the drawings]

FIG. 1 is a graph showing a relationship between a final stand rolling force and a cross buckle size.

FIG. 2 is a graph showing the relationship between the final stand rolling force and the transfer rate of roughness at the final stand.

FIG. 3 is a graph showing an example of a relationship between a rolling speed and an appropriate rolling force with respect to a cross buckle in the present invention.

FIG. 4 is a diagram showing a specific example of a change in the size of the cross buckle and the plate surface roughness when the rolling force control of the present invention is performed.

FIG. 5 is a block diagram of one embodiment of an apparatus suitable for performing the method of the present invention.

FIG. 6 is a diagram showing an example of a change in the size of the cross buckle and the plate surface roughness when the rolling force control of the present invention is not performed.

FIG. 7 is an explanatory diagram of a method for measuring a cross buckle.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Strip 2 Temper rolling mill 2a Work roll 2a 'Work roll 3 Rolling speed detector 4 Rolling speed signal converter 5 Memory operation unit 6 Amplifying device 7 Rolling force control mechanism 8 Rolling force detector 9 Rolling force signal converter 10 Cross Buckle target value setting input means 11 Stylus

Claims (1)

(57) [Claims] In the temper rolling of a steel strip, an appropriate rolling force in a final stand for keeping the size of a cross buckle constant according to a rolling speed is determined in advance, and the final stand is reduced by the proper rolling force. A rolling force control method in temper rolling of a steel strip, characterized by the following.