JPH06262205A - Hot rolling method and hot rolling mill train - Google Patents

Abstract

PURPOSE:To produce a metal plate excellent in surface quality while avoiding a remarkable rise of cost by executing rolling while the surface of a work roll during rolling is ground through a mill which performs rolling in a specified range of a ratio Xi of a rolling reaction Pi to the width W of a material to be rolled. CONSTITUTION:When the ratio of the rolling reaction Pi to the width W of the material to be rolled is made Xi in the i-th mill of a hot tandem mill composed of 5-7 rolling mills, a work roll grinding equipment 3 is equipped in an object mill wherein rolling is performed in the area of Xi of <=1.3 at least. While a stainless steel is rolled, the surface of the work roll 1 is ground in stands F1, F2, F3. As a result, the high-quality metal plate excellent in surface property can be produced with a high efficiency and can be produced with a remarkably high efficiency and at a low cost. Only a small number of reformed mills serve the purpose even in the existing rolling line and a low cost plant and equipment investment will do.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot rolling method and a hot rolling mill train capable of efficiently producing a strip-shaped metal material having a good surface condition.

[0002]

2. Description of the Related Art For example, in rolling a metal material such as steel, a high rolling load is applied at a high temperature, so that the surface of a work roll is gradually roughened. Therefore, the rough surface of the work roll is transferred to the surface of the rolled plate material, and the surface quality of the plate material deteriorates. Once the surface of the plate material becomes rough, the surface of the plate material does not recover to a good surface even if it is later rolled with a work roll having a good surface. Therefore, it must be replaced with a work roll whose surface has been polished at an early stage. When the number of work roll reassembling increases, there is a problem that the production efficiency is greatly reduced.

In order to solve the above problems, the rolling mill entrance side thickness is reduced. Increase the temperature of the rolling material on the inlet side of the rolling mill. Lubricate the work rolls. Etc. are taken. However, when the thickness on the rolling entry side is reduced and the temperature on the rolling entry side is increased, it is necessary to significantly increase the heating temperature of the material to be rolled, resulting in a large cost increase in energy saving. Further, the method of injecting the lubricating oil to the work roll has a problem that the rolling roll slips at the start of rolling or during rolling, and a stable rolling state cannot be maintained.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a hot rolling method and equipment for producing a plate material having a good surface quality while avoiding a significant increase in cost.

[0005]

The gist of the present invention is as follows. (1) When the ratio of the rolling reaction force P _i (tonf) to the rolled material width W (mm) in the i-th rolling mill of the hot tandem rolling mill consisting of 5 to 7 rolling mills is X _i , A hot rolling method characterized in that, in a rolling mill that rolls at least in a region where X _i is 1.3 or more, rolling is performed while grinding the surface of a work roll being rolled.

(2) Rolling reaction force P _i (to in the i-th rolling mill of the hot tandem rolling mill consisting of 5 to 7 rolling mills)
When the ratio of nf) to the width W (mm) of the rolled material is X _i , the hot rolling is characterized by incorporating a roll grinding device into a rolling mill that rolls at least in the region where X _i is 1.3 or more. Machine train.

The reduction of the work roll surface is greatly influenced by the magnitude of the rolling reaction force, and has a strong correlation with the rolling reaction force X _i per unit width (i is a sign corresponding to the rolling mill) expressed by the following equation: X _i = P _i ÷ W P _i ; Rolling reaction force (tonf) W; Rolled material width (mm) The inventors of the present invention set the rolling condition in which the surface of the work roll is apt to be rough, that is, X as shown in FIG. It has been experimentally found that _i ≧ 1.3, and the present invention has been constituted in which the surface of the work roll is ground during rolling only by the rolling mill satisfying this condition. Figure 1 shows the occurrence rate of surface defects (scale defects, etc. due to rough surface of hot rolled sheet) of the final product sheet when stainless steel is hot-rolled and formed into a product sheet by a normal method ) Of the rolling reaction force per unit width during hot rolling (Max value of each stand). It is clear that the surface flaw occurrence rate sharply increases in the above range of X _i ≧ 1.3. is there. Since it is desirable to grind work rolls during rolling with as few rolling mills as possible, and the roll grinder itself is an expensive facility and a large investment is required to place it on all stands, so the minimum range is According to the present invention installed in the rolling mill of the present invention, the above problems can be better solved.

[0008]

FIG. 2 shows a hot rolling mill train according to an embodiment of the present invention.
In the figure, 1 is a work roll, 2 is a reinforcement roll, and 3 is an upstream side F1, F2, F of all stands (6 stands).
It is a work roll grinder provided on three stands.

The rolling mill specifications and rolling conditions are shown in Table 1. The work roll grinding device was installed in the target rolling mills (F1, F2, F3 stands) corresponding to the rolling conditions of X _i ≧ 1.3. As a result, the surface quality level of the material to be rolled after the rolling of 10 to 20 rolls has conventionally been lowered and the work rolls have to be recombined, whereas F1, F2,
By grinding the work roll surface with the F3 stand, the surface quality of the material to be rolled could be kept good even after rolling about 100 rolls. In the examples, an example in which the material to be rolled is stainless steel has been shown, but other steel grades have the same effect.

[0010]

[Table 1]

[0011]

By constructing and carrying out the present invention as described above, it is possible to produce a high-quality plate material having a good surface texture with high efficiency, and it is much more efficient and less costly than the prior art. Can be produced. Even with existing rolling lines, it is sufficient to modify only a few rolling mills, and low-cost capital investment is required.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between a surface quality of a material to be rolled and a rolling reaction force per unit width.

FIG. 2 is an explanatory diagram showing an embodiment of the present invention.

[Explanation of symbols]

 1 Work roll 2 Reinforcement roll 3 Work roll grinder

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Naoyoshi Kurahara 1 Kimitsu, Kimitsu-shi, Chiba Nippon Steel Corp. Kimitsu Steel Co., Ltd.

Claims (2)

[Claims] 1. A rolling reaction force P _i (tonf) in an i-th rolling mill of a hot tandem rolling mill comprising 5 to 7 rolling mills.
When the ratio of the rolled material width W (mm) to X _i is X _i , in a rolling mill that rolls at least in the region where X _i is 1.3 or more, it is necessary to roll while grinding the surface of the work roll being rolled. Characteristic hot rolling method. 2. A rolling reaction force P _i (tonf) in an i-th rolling mill of a hot tandem rolling mill comprising 5 to 7 rolling mills.
If the ratio of with respect to the rolled material width W (mm) was X _i, hot rolling mill train, characterized in that incorporates a roll grinding apparatus in the rolling mill at least X _i is rolled at 1.3 or more areas .