JPH0360803A - Cold rolling method for stainless steel strip - Google Patents

Abstract

PURPOSE:To equalize the elongation and to prevent the generation of chatter by rolling with the use of upper two intermedium driving rolls having smaller diameter than that of the lower two intermedium driving rolls. CONSTITUTION:A stainless steel strip 1 is wound by a tension reel 8 via a deflecting roll 7 after its rolling by a work roll 2. In that case, the cold rolling is executed by using the Sendzimir mill of the upper two intermedium driving rolls 4A having a smaller diameter than those of lower two intermedium driving rolls 4B. Consequently, the difference in the upper and lower forward slip of a stainless steel strip 2 can be made zero and the generation of chatter can be prevented.

Description

Detailed Description of the Invention <Industrial Application Field> The present invention is directed to the prevention of surface defects called chatter, which is a fine waving phenomenon that occurs on the front and back surfaces of copper strips during cold rolling of stainless steel strips, particularly rolling with a Sendzimir mill. The present invention relates to a rolling method suitable for preventing cracking.

<Prior Art> When a stainless steel strip is cold rolled by a Sendzimir mill, temporary undulation-like defects called chatter that are not accompanied by changes in the strip thickness occur. Chatter is a chatter mark with a wave height of several pH and a pitch of 5 to 30 III m, and is characterized in that it does not occur when the total rolling reduction during cold rolling is 40% or less.

Conventionally, as a preventive measure against this, Japanese Patent Application Laid-Open No. 58-11010
As disclosed in Publication No. 4, this does not occur when the total rolling reduction is less than 40%. Therefore, if the total rolling reduction does not exceed 40% and cold rolling is required, the following method should be used when the rolling reduction is less than 40%. This has been dealt with by a so-called two-step rolling method in which rolling is performed in separate rolling steps and an intermediate annealing step is provided in between. That is, the steps are: 1st rolling → intermediate annealing → 2nd rolling → final annealing.

<Problems to be Solved by the Invention> However, the above-mentioned two-step rolling method increases the step of intermediate annealing, resulting in energy loss, handling loss, and processing f! I! IflTA is an extension of time If! ff
was there.

The object of the present invention is to provide a method for cold rolling stainless steel strip that solves these problems.

Means for Solving the Problems The present invention is characterized in that when 4tF stainless steel is cold rolled by a Sendzimir mill, upper two intermediate drive rolls having a smaller diameter than the lower two intermediate drive rolls are used. This is a cold rolling method for stainless steel/11F, and the diameter of the upper two intermediate drive rolls is 0.3
Stainless steel w4 characterized by ~0.8% smaller size
This is a method of cold rolling a strip.

The present inventor has studied various mechanisms of occurrence of chatter, and found that when rolling stainless steel strips in a Sendzimir mill, the advance rate of the upper and lower surfaces is always equal to rolling = E, as shown in Fig. 2.
The advancement rate of the surface is large, in other words, the extension of the top surface is large,
Therefore, as shown in FIG. 3, it has been found that the material that leaves the work roll 2 is always lifted downward by l1f1, and then is moved by 1111 V in the opposite direction due to the winding tension of the tension reel, causing waviness in the board.

The present invention focuses on the fact that the cause of this chattering is due to the difference in elongation between the upper and lower rolling surfaces, and when cold rolling a stainless steel strip using a Sendzimir mill, the upper two intermediate drive rolls have a smaller diameter than the lower two intermediate drive rolls. By rolling at different speeds on the upper and lower surfaces, the elongation is made the same and the occurrence of chatter is prevented.

In addition, the present invention can improve stainless steel rolled in a Sendzimir mill by making the diameter of the upper two intermediate drive rolls 0.3 to 0.8% smaller than the diameter of the lower two intermediate drive rolls. I
It is now possible to reduce the difference between the upper and lower advance rates of F to zero, and the total rolling reduction rate does not exceed 40% without causing chattering.
could be cold rolled using the same method.

Here, the reason why the diameter of the upper two intermediate drive rolls is set to be 0.3 to 0.8% smaller than the diameter of the lower two intermediate drive rolls is that it is sufficient to make the roll diameter difference smaller than 0.3%. On the other hand, if it is made larger than 0.8%, there will be a problem in that the rolling advance ratio of the lower surface of the roll will be larger than that of the upper surface.

<Example> Embodiments of the present invention will be described based on the drawings.

To explain the roll arrangement of the Sendzimir mill using Fig. 1, work rolls 2 and 2 are placed from the stainless steel strip l side. There is an intermediate roll 3, followed by upper two intermediate drive rolls 4A, upper two intermediate idle rolls 5A, lower two intermediate drive rolls 4B,
The same idle roll 5B is arranged in the lower two, and a backup bearing 6 is provided at the end. stainless steel strip 1
is rolled by a work roll 2, passed through a deflector roll 7, and then wound up by a tensile reel 8.

Then, upper and lower two intermediate drive rolls 4A and 4B with the following dimensions
(In this example, the diameter of the upper 2 middle G11 drive roll 4A is about 0.6% smaller than the diameter of the lower 2 middle drive roll 4B). Diameter to: 180m Bottom 2 Diameter of intermediate drive roll 4B: 1B1wa JV 4f1m x width 1100 (1
Steel type 5US430 stainless steel M4tF with total reduction rate of 75
When cold rolling was performed by one-pass rolling at ~85%,
There was no occurrence of chatter, and the surface quality was good.

<Effects of the Invention> According to the present invention, as is clear from Example 1iii.
When cold rolling a stainless steel sheet using a Sendzimir mill, the occurrence of chatter can be prevented by rolling it using the upper two intermediate WJ rolls, which have a smaller diameter than the lower two intermediate drive rolls. The total rolling reduction rate that occurs is 4
In the case of rolling exceeding 0% °ζ, the conventional two-step rolling process can be reduced to one-step rolling process, and intermediate annealing and secondary rolling can be omitted, reducing energy and material handling to 2/3 of the conventional method. It has the effect of reducing

[Brief explanation of the drawings] Fig. 1 is an explanatory diagram schematically showing the roll arrangement of the Sendzimir mill, Fig. 2 is a diagram showing the advance rate of the upper and lower surfaces of the rolled plate in the Sendzimir mill, and Fig. 3 is a diagram showing the chatter in the Sendzimir mill. It is a cross-sectional view without showing the mechanism of occurrence. 1... Stainless steel"jjF. 2... Work roll, 3... First intermediate roll, 4A... Upper 2 intermediate drive rolls, 4B... Lower 2 intermediate drive rolls, 5A... Upper 2 intermediate idle rolls, 5B...lower 2 intermediate idle rolls, 6...buffer bearing, 7...deflect roll, 8...tension reel.

Claims (2)

[Claims] (1) A method for cold rolling a stainless steel strip, which comprises using upper two intermediate drive rolls having a smaller diameter than the lower two intermediate drive rolls when cold rolling the stainless steel strip using a Sendzimir mill. (2) The method for cold rolling a stainless steel strip according to claim 1, wherein the diameter of the upper two intermediate drive rolls is 0.3 to 0.8% smaller than the diameter of the lower two intermediate drive rolls.