JP2002282920A - Method for controlling of camber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method to manufacture a flat metal product free from camber efficiently at low cost in a method for plate rolling of a material. SOLUTION: When a rolling mill with at least two work rolls, one top and one bottom, having different axial directions, conducts reverse rolling, the method to rotate the top and the bottom work rolls at different circumferential speeds enables the manufacturing of the flat metal product free from camber.

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 a camber generated by rolling a sheet metal product.

[0002]

2. Description of the Related Art It is extremely important to accurately control a camber during rolling so that a planar shape of a plate to be rolled becomes almost rectangular in order to secure a high yield and to stabilize the shape. It is. Therefore, various online models for controlling the camber have been developed. For example, Japanese Unexamined Patent Publication
Japanese Patent Publication No. 182418 discloses a method of controlling the left and right roll gaps for each pass. This is because, in rolling of each pass, according to the sheet width, the sheet thickness, the rolling reduction, etc., the right and left rolling amount difference Δhdf of each pass for which the camber is to be corrected is determined. The roll gap difference Δgdf for realizing Δhdf is calculated.

[0003]

Problems to be Solved by the Invention
In the method for adjusting the roll gap as disclosed in Japanese Patent Publication No. 8 (1999) -1999, in addition to the sheet width and the sheet thickness and the rolling reduction, it is necessary to determine the difference Δhdf between the left and right rolling reductions in each pass. Therefore, it is necessary to obtain the roll gap difference Δgdf in consideration of the deformation of the mill, and there is a problem that a complicated calculation model is essential. Of course, empirically, Δ
gdf can also be obtained. In this case, the sheet thickness, sheet width, rolling reduction, camber amount to be corrected, Δhdf, Δgdf
, It is necessary to obtain all the relationships, and there is a problem that a huge amount of data processing is required.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention solves the above problem by performing upper and lower work rolls in different rolling directions when performing reverse rolling in a rolling mill in which two upper and lower work rolls have different axial directions. It is characterized in that it is rotated at a speed and rolled to correct the camber of the plate.

That is, the gist of the present invention is as follows.
It is as follows. In the camber control method, when reverse rolling is performed in a rolling mill in which at least two upper and lower work rolls have different axial directions, the upper and lower work rolls are rotated at different peripheral speeds, and rolling is performed so as to correct the plate camber. And a camber control method. Further, preferably, in the above-described camber control method, the work roll in which the direction of movement of the control target plate and the direction perpendicular to the roll body length direction coincide with each other at a larger peripheral speed than the other work roll. A camber control method characterized in that rolling is performed so as to correct the camber of a plate by rotating the camber. More preferably, in the above camber control method, in the path before the final path,
Rolling is performed by giving at least a difference between the upper and lower work roll peripheral speeds, and in the final pass, rolling is performed by matching the upper and lower work roll peripheral speeds, and rolling is performed so as to correct the plate camber. Is a control method.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.
This will be described in detail. FIG. 1 shows a rolling mill in which the upper and lower work rolls have different axial directions (hereinafter referred to as a cross roll mill).
Here, an example of performing reverse rolling will be described. The rolled material 3 is rolled by the upper work roll 1 and the lower work roll 2.

Here, 1/2 of the angle between the upper work roll 1 and the lower work roll 2 in the axial direction is called a cross angle. The purpose of giving such a cross angle (hereinafter, defined as θ) to a rolling mill is to control the sheet crown. Usually, the peripheral speed of the roll is equal in the upper and lower work rolls. In this case, even if the cross angle θ changes, the plate is symmetrical as shown in FIG. If there is no difference between the left and right of the inlet side plate thickness and the temperature distribution), the planar shape is left-right symmetric even after rolling. However, when the cross angle θ ≠ 0 °, if the upper and lower work rolls are rolled at different speeds (hereinafter referred to as different peripheral speed rolling), the plate 3 is bent and rolled as shown in FIG. It has been found that the planar shape becomes left-right asymmetric.

Accordingly, the inventors have further investigated in detail the cross angle θ, the roll peripheral speed, and the bending of the plate. As a result, it has been found that the bending direction of the plate is closely related to the cross angle and the roll peripheral speed, and that the plate bends in a direction perpendicular to the roll body length direction of the work roll having a high peripheral speed. For example, in the case of FIG. 2, since the lower work roll 2 has a high speed, the plate bends in a direction perpendicular to the body length direction of the lower work roll. Of course, as shown in FIG. 3, when the upper work roll 1 is at a high speed, it goes without saying that the upper work roll 1 bends in the opposite direction.

Even if the sheet thickness, rolling reduction, and sheet width slightly vary, if the cross angle is constant, the different peripheral speed rate で defined by the following equation (1) and the curvature of the generated curve are substantially constant. I also found something. It has also been found that, for the same cross angle, the curvature of the bend increases monotonously as the different peripheral speed increases. Therefore, in order to obtain the desired curvature of curvature, the relationship between the camber curvature and the different peripheral speed rate for each cross angle is obtained by an experiment or the like, a regression equation or a table is prepared, and rolling is performed based on the value. good. Further, if necessary, a detailed correction may be performed for the sheet thickness, the draft, the sheet width, and the steel type. Definition of different peripheral speed ratio χ χ = (upper roll speed-lower roll speed) / high-speed roll side speed (%) ... (1)

Further, as a result of investigating the relationship between the above characteristics and the controllability with respect to the camber, if a camber indicated by a dotted line in FIG. It has also been found that if a bend is given to a sheet by different peripheral speed rolling (solid line in FIG. 4), camber is eliminated as shown in FIG. 5 and a symmetric rolled material can be obtained. Therefore, in order to control the camber based on the above knowledge, the curvature of the generated camber is predicted (or measured in the previous pass), and a different peripheral speed rate for eliminating the curvature of the camber is given during rolling. I found something good.

[0011] When different peripheral speed rolling is performed, warpage occurs due to the vertical asymmetry. If the camber amount to be controlled is small, the different peripheral speed ratio to be applied is also small, so that the warpage is small and the occurrence of the warp may be ignored. However, if the camber amount to be controlled is large, the different peripheral speed ratio to be provided is also large, and the generated warpage is also large. Therefore, some countermeasures are necessary.

[0012] Therefore, the behavior of warpage was also investigated. The details are shown below. Different peripheral speed rolling with a cross angle was performed, and the warpage generation behavior was observed. As a result, it was found that the warpage occurred only at the leading end of each pass and did not occur at the tail end. Therefore, even if considerable warpage occurs in the previous pass, the warpage exists at the tail end in the next pass, and there was no problem in rolling in the next pass.

However, if different peripheral speed rolling is performed even in the final pass, warpage remains. Therefore, the camber was corrected by the pass before the final pass, and the same pass rolling was performed in the final pass. As a result, it was found that the warpage that had occurred up to the previous pass was eliminated in the final pass. Therefore, in the pass before the final pass, at least the upper and lower work roll speeds are given a difference to perform rolling to correct the camber, and in the final pass, rolling is performed so that the upper and lower work roll peripheral speeds match, so that the camber is also reduced. It has been found that a plate without warpage can be manufactured. If the curvature of the camber changes in the middle of the plate, the different peripheral speed ratio may be changed accordingly.

[0014]

EXAMPLE Hot rolling of a steel sheet was performed using a reverse rolling mill having a work roll diameter of 1000 mm. First of all,
The camber generated at that time was measured by changing the different peripheral speed ratio for each cross angle θ, and the graph shown in FIG. 6 was obtained. In addition, regarding the sign (positive / negative) of the camber, the bending direction shown in FIG. Table 1 shows the rolling conditions at this time. It can be seen that despite the considerable variations in plate thickness, plate width, and rolling reduction, the generated camber curvature can be better organized with different peripheral speed rates.

Next, with reference to FIG. 6, a control for eliminating camber generated in the previous pass by different peripheral speed rolling in the next pass was performed on 100 slabs. As a comparative example, rolling was performed at the same peripheral speed on the same rolling schedule as 100 slabs described above. Table 2 shows the average values of the absolute values of the camber curvatures of the example and the comparative example. In the example, it can be seen that the amount of camber generated is very small. On the other hand, in the comparative example, a large camber occurred.

[0016]

[Table 1]

[0017]

[Table 2]

[0018]

According to the method of the present invention, since the camber of the plate can be remarkably reduced, the planar shape of the product can be greatly improved, and a great effect can be obtained in reducing the rolling cost.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example in which rolling is performed in rolling mills having different axial directions of work rolls.

FIG. 2 is a diagram showing the bending of a plate when a lower roll is set to a high speed.

FIG. 3 is a view showing the bending of a plate when the upper roll is set to a high speed.

FIG. 4 is a diagram showing a method for eliminating camber by different peripheral speed rolling.

FIG. 5 is a diagram in which camber is eliminated by different peripheral speed rolling.

FIG. 6 is a diagram showing a relationship between different peripheral speed factors and camber curvature.

[Explanation of symbols]

 1 upper work roll 2 lower work roll 3 rolled material

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Tomoki Seki 1 Kimitsu, Kimitsu City, Chiba Prefecture Inside Nippon Steel Corporation (72) Inventor Takashi Hisatsune 1 Kimitsu, Kimitsu City, Chiba Prefecture Nippon Steel Corporation F term in the Kimitsu Works (reference) 4E024 AA06 CC04 DD20 EE02

Claims (3)

[Claims] In a camber control method, when reverse rolling is performed by a rolling mill in which at least two upper and lower work rolls have different axial directions, the upper and lower work rolls are rotated at different peripheral speeds, and the plate camber is rotated. A camber control method, characterized by rolling to straighten. 2. A cam roll of a plate is rotated by rotating a work roll whose direction of advance of a control target plate and a direction perpendicular to the roll body length direction coincide with each other at a larger peripheral speed than the other work roll. 2. The camber control method according to claim 1, wherein the rolling is performed as described above. 3. In the pass before the final pass, rolling is performed by giving at least a difference between the upper and lower work roll peripheral speeds, and in the final pass, rolling is performed by matching the upper and lower work roll peripheral speeds, and the plate 3. The camber control method according to claim 1, wherein rolling is performed so as to correct the camber.