JPH05185105A - Method for rolling thick plate - Google Patents

Abstract

PURPOSE:To provide a means for optimizing width shape and crop shape at the tip and rear end of a steel sheet after rolling. CONSTITUTION:At the time of executing rolling for thick plate by using a horizontal roll mill 2 and edger 1 jointly, edging is executed to the vicinity of the tip and rear end of product so that the vicinities of biting end and running-out end of the edger 1 are at a draft less than the reference rolling reduction in the middle part before, after, or in the process of cross rolling. In this way width drop in the vicinity of the tip and rear end of steel sheet after rolling can be prevented and also width shape and crop shape can be simultaneously optimized. The rectangular product with extremely small cut- down part and high yield can be manufactured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for rolling a thick plate including tenter rolling, which uses an edger to make the flat shape of the rolled steel sheet rectangular so as to reduce the cutting loss at both side ends and front and rear ends. ..

[0002]

2. Description of the Related Art Generally, in plate rolling, it is an object to obtain a flat rectangular steel plate having a predetermined width and length by rolling a flat rectangular slab in the width direction and then in the longitudinal direction. .. This thick plate rolling is usually performed by a horizontal rolling mill, but in the case of rolling only by a horizontal rolling mill, the plane shape of the steel sheet after rolling depends on the rolling conditions, and the plan shape is as shown in FIG. It becomes a dogleg shape as shown in (B). The claw-shaped planar shape is used when the width ratio (width of rolled steel sheet / width of slab before rolling) is small and the stretched length ratio (length of steel sheet after rolling / length of slab before rolling) is large. It occurs and has a tongue-shaped crop shape and a width expansion near the front and rear ends. Also, the taiko-shaped plane shape occurs when the width ratio is large and the stretch length ratio is small,
It has a narrow width near the front and rear ends and a fishtail-like crop shape.

In order to obtain a product steel sheet having a predetermined width and length from such a flat rolled steel sheet, an extra width and an extra length should be given to the rolled steel sheet in advance and the extra portion should be discarded. I have to. In order to reduce the cut-off loss, a method of using a horizontal rolling mill and an edger together to bring the planar shape closer to a rectangle (hereinafter referred to as “edger method”) is widely adopted in plate rolling. This edger method is a method of reducing the side crop amount and end crop amount by an edger (vertical roll) after forming pass or tenter rolling, and mainly reduces the end crop amount by edging in the longitudinal direction and the side crop amount by lateral edging. This is a method to control the amount of crop.

For example, FIG. 5 (A) illustrates a method for improving the splanchoid planar shape by the edger method. After horizontal rolling in the width direction of the steel sheet (hereinafter referred to as "tentering rolling"), Before and after or during the horizontal rolling of the steel sheet in the longitudinal direction (hereinafter referred to as "finish rolling"), edging portions that contact both side edges of the steel sheet (hereinafter referred to as "finish edging")
By doing so, the widened portion in the vicinity of the front and rear ends is caused to wrap around the front and rear ends, and the width spread and the tongue-shaped crop shape are improved. FIG. 5 (B) shows an example of a method for improving the planar shape of the trough shape. By edging the portion corresponding to the front and rear edges of the steel plate before and after or during the tenter rolling (hereinafter referred to as “tenter edging”). , The fishtail-shaped crop portion is wrapped around in the width direction to improve the fishtail-shaped crop and the narrowing.

[0005]

As described above, when the edger method is used, the plane shape of the steel sheet is significantly improved.
The conventional edger method has a limit in the planar shape improving effect. FIG. 6 (A) is an example in which a strong reduction is performed by finishing edging in order to improve the tongue-shaped crop in the zigzag planar shape. In this case, since the width of the biting end and the trailing edge at the time of edging is narrower than that of the central portion, such a strong reduction in finishing edging causes a decrease in width near the front and rear ends. Further, FIG. 6B is an example in which strong reduction is performed by tentering edging in order to improve the narrowing of the width in the vicinity of the front and rear ends in the planar shape of the trough. In this case, although the narrowing is improved, the crop becomes tongue-shaped. That is, in both cases shown in FIGS. 6A and 6B, the strong reduction of the edging leads to another planar shape defect different from the case where the edging is not performed. In other words, with the conventional edger method, it is impossible to simultaneously optimize the width shape and the crop shape near the front and rear ends.

On the other hand, Japanese Patent Publication No. 57-48286 proposes a method for improving the planar shape of a staggered shape or a trough shape. This method is a method in which the roll opening is continuously or stepwise changed in the same plate during finishing edging to obtain a product having the same width from the front end to the rear end. In addition, this method also has the effect of improving the tongue-shaped crop shape under the rolling conditions in which the planar shape when not edging is a staggered shape. However, there is a possibility that the leading and trailing edge cropped shapes may be deteriorated with respect to the flat shape of the trough, and it is not applicable to rolling with a large width-to-width ratio.

As described above, the conventional edger method has a limit in the effect of improving the planar shape, and it is impossible to simultaneously optimize the width shape and the leading and trailing edge cropping shape especially when the width ratio is large.

According to the present invention, as compared with the above-described conventional state, when the flat shape of the rolled steel sheet becomes a trough shape only by the horizontal rolling machine having a large width-drawing ratio, the width shape and the front and rear edges of the rolled steel sheet It is intended to propose a thick plate rolling method capable of optimizing the crop shape.

[0009]

According to the present invention, when a thick plate is rolled by using the edger method, before and after or in the middle of tenter rolling, the edge of the edger near the biting edge and the edge of the trailing edge are reduced by a reference pressure at the central portion. The gist of the invention is to edging the front and rear ends of the product so that the pressure is slightly lower than the amount.

[0010]

In the present invention, before and after or during the tenter rolling, the edges of the product are edged so that the edger biting end and the tail trailing end are lightly pressed down from the central reference amount. The reason is as follows. That is, in finishing edging, if the vicinity of the edger biting end and the butt trailing end is made equal to or stronger than the reference reduction amount of the central part, the width of the biting end and the butt trailing end at the time of edging becomes narrower than that of the central part. This is because the width of the front and rear ends is reduced. Therefore, by performing the tentering edging by the edger method of the present invention, it is possible to prevent the width reduction near the front and rear ends of the rolled steel sheet, and increase the edger opening degree when the edger is engaged and the trailing edge is removed, and the edging is performed. By reducing the pressure slightly, the width shape and the crop shape can be optimized at the same time. As a result, it is possible to obtain a rectangular product with a high yield and very little end crop without increasing the side crop.

FIG. 7 conceptually illustrates a comparison between the conventional edger method and the thick plate rolling method of the present invention. FIG. 7 (a) shows a steel sheet in the case of rolling at a width ratio with no edging. Plane shape change, (b) Plane shape change of steel sheet when tentered edging is performed, (c) Plane shape change of steel sheet when roll opening is changed during finishing edging, (d) Present invention The changes in the plane shape of the steel sheet by the method are shown respectively, and the shaded portion in the figure is the cut-out portion.

That is, in the case of (a), since only horizontal rolling occurs, side crops and end crops occur,
A large amount of steel sheet is discarded. In the case of (b), narrowing is improved, but the amount of tongue crop is large. In the case of (C), the shape of the front and rear end crops deteriorates, and the amount of steel sheet cut off is large. On the other hand, in the case of (d) according to the method of the present invention, it is possible to prevent the width fall near the front and rear ends of the rolled steel sheet by performing the tentering edging as described above, and at the time of edger biting and butt The width and crop shapes can be optimized at the same time by increasing the edger opening and lightly reducing it when it comes out, resulting in the loss of steel sheet cutting as shown in (a), (b), and (c). Rectangle products can be obtained without.

[0013]

FIG. 1 is a schematic view showing an example of the construction of an apparatus for carrying out the method of the present invention. 1 is an edger, 2 is a horizontal rolling mill,
3 is an edger control device, 4 is a horizontal rolling mill control device, and 5 is a computing device. FIG. 2 is a flowchart for calculating a rolling pass schedule, an edging timing, an edging pattern, etc., in the arithmetic unit of the above apparatus.

That is, when carrying out the method of the present invention, as shown in FIG. 1, the horizontal rolling pass schedule, the edging timing, the edging pattern, etc. are determined by the arithmetic unit 5, and the horizontal rolling mill control unit 4 and the edger are based on them. The control device 3 controls the horizontal rolling mill 2 and the edger 1.

The arithmetic unit 5 first determines a horizontal rolling pass schedule based on rolling conditions such as target dimensions of the slab and the rolled steel sheet. Next, from the determined horizontal rolling pass schedule, the shape of the steel sheet after rolling when horizontal rolling is performed is predicted, and the timing of the tentered edging and the rolling pattern are determined based on the predicted value. From the viewpoint of edging efficiency, it is preferable to carry out the edging timing at a stage where the plate thickness is large, that is, at the rolling upstream pass, unless there are restrictions such as facilities. In addition, finishing edging may be combined as necessary during finishing rolling after tenter rolling.

FIG. 3 shows a slab having a thickness of 235 mm, a width of 2000 mm and a length of 2250 mm, and a steel plate having a thickness of 16 mm.
It is an example of an optimum edging pattern when the method of the present invention is applied to a thick plate rolling of mm × width 4700 mm × length 14000 mm. The edging timing is before the tenter rolling. As shown in this figure, the flatness of the rolled steel sheet can be made rectangular by increasing the edging amount at the time of edger biting and at the time of slipping out and increasing the central portion.

Example 1 Comparison of the width cut-off amount and the front and rear end crop cut-off amount of a rolled steel sheet when the method of the present invention is applied to the production of thick plate rolling with various slab dimensions and steel sheet dimensions shown in Table 1 is compared with the conventional method. And shown in Table 2. In the figure, Conventional method 1 is a case where a normal edger method is applied (FIG. 7b), and Conventional method 2 is a case where the roll opening is changed during finishing edging (FIG. 7c).

As is clear from the results in Table 2, the width profile of the steel sheet can be optimized by the method of the present invention, while the leading edge and trailing edge crop configurations can be significantly improved. As a result, a high yield can be achieved and the cost of the thick steel sheet can be reduced. Has a great effect on.

[0019]

[Table 1]

[0020]

[Table 2]

[0021]

As described above, according to the method of the present invention, the width shape and the crop shape of the steel sheet can be optimized at the same time when the horizontal rolling machine and the edger are used together to perform the plate rolling. It is possible to obtain a rectangular product with a high yield and very little end crop without increasing the side crop, and it is very effective in reducing the manufacturing cost of thick steel plates.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an example of a device configuration for carrying out the method of the present invention.

FIG. 2 is a flowchart for calculating a rolling pass schedule, edging timing, edging pattern, etc. in the arithmetic unit of the above apparatus.

FIG. 3 is a diagram showing an example of an optimum width-cutting edging pattern when the method of the present invention is applied to actual thick plate rolling.

FIG. 4 is a view exemplifying a planar shape of a steel plate after rolling in a conventional thick plate rolling, in which (A) is a tabular planar shape and (B) is a plan view.
It is an explanatory view showing each horizontal plane shape.

FIG. 5 is a diagram illustrating a conventional planar shape improving method by an edger method, in which (A) is an explanatory view showing a method for improving a planar shape of a lump and (B) is an explanatory view showing a method for improving a flat planar shape. is there.

6A and 6B exemplify a conventional planar shape improving method by an edger method, in which FIG. 6A is a tongue-shaped crop improving method in a staggered planar shape, and FIG. It is explanatory drawing which each shows the narrowing improvement method.

FIG. 7 is a schematic view conceptually showing a comparison between the conventional edger method and the plate rolling method of the present invention.

[Explanation of symbols] 1 edger 2 horizontal rolling mill 3 edger control device 4 horizontal rolling mill control device 5 arithmetic unit

Claims (1)

[Claims] 1. When rolling a thick plate using a horizontal roll rolling mill and an edger, before and after or during the tenter rolling, the edger biting end and the tailing end are lightly reduced from the reference reduction amount at the center. The method of rolling a thick plate characterized by edging the front and rear ends of the product so that