JPS58202903A - Rolling method of strip - Google Patents

Abstract

PURPOSE:To prevent the wrapping and sagging of a strip and to roll the same stably under high rolling reduction in rolling with single stand and multiple passes by using work rolls of which the surface roughness is made successively coarser as the roll position is nearer the outlet side of a rolling mill. CONSTITUTION:Work rolls 1, 2-n, n+1 form rolling passes P1, P2-Pn with the adjacent rolls successively from the inlet side of a rolling mill. Backup rolls 11, 12 are disposed above and below the work roll train. A strip S is rolled in the passes P1-Pn while the same is wound approximately half-circumferentially on the work rolls 2-n. The surface roughness of the rolls 1-(n+1) in such roll constitution is determined at Rn+1>Rn>->R1 where said roughness (mean square root of roughness) is specified as R1, R2-Rn+1 respectively. The difference in the surface roughness of the adjacent work rolls in this case is kept preferably at about >=0.01mum.

Description

[Detailed description of the invention] The present invention relates to a method of rolling metal strip.

A method of rolling a strip by passing the material continuously through a stand (single-stand multi-pass rolling) so as to form two or more rolling passes [three or more work rolls are arranged in a row and these rolling passes]. law) is known.

During rolling, the strip is wrapped approximately half a circumference around the work roll. In this rolling method, one rolling stand can perform rolling for a plurality of rolling stands, so it has the advantage that the entire rolling equipment can be downsized and the equipment cost can be reduced.

When rolling a strip by arranging a plurality of rolling stands in tandem, the strip may break due to tension. Therefore, it is necessary to suppress the tension applied to the strip to a low value (for example, 20 kg/- or less). on the other hand,
If the tension is too low, the strip wraps around the work roll sag. When the slack of the strip increases, the strip moves (walks) in the width direction.

As the sagging progresses further, the (i) II lobes overlap in a wrinkled manner and pass through the roll gap, resulting in so-called squeezing, and finally the (i) IJ lobes break, resulting in the inability to roll.

In addition, sagging of the strip becomes more likely to occur as the rolling reduction ratio increases.

This invention was made in order to solve the above-mentioned problems in the one-stand multi-bus rolling method, and it is possible to prevent the strip from sagging when wound around the work roll and to stably roll the strip under high pressure. By providing a strip rolling method that can

In the sl-IJ shingle rolling method of the present invention, in one-stand multi-pass rolling, the shiss strip is rolled by work rolls whose surface roughness becomes progressively rougher as the roll position moves closer to the rolling mill side.

As mentioned above, if the surface roughness of the work roll on the rolling mill side (downstream side) is rough, the frictional force between the strip wound around the work roll on the downstream side and the work roll becomes large.

As a result, the strip becomes pulled by the downstream work roll.

Therefore, even if the tension applied to the strip is quite low, the winding of the strip around the work roll will not sag.

In this invention, as mentioned above, since the winding of the strip does not easily sag, the strip can be stably rolled even under a high rolling reduction ratio.・1. be able to.

Hereinafter, this one invention will be explained in detail.

FIG. 1 schematically shows the roll arrangement of a one-stand n-bus rolling mill. Work roll 1゜2...
n and n+1 form rolling passes PH+, P2, . . ., Pn sequentially from the entrance side of the rolling mill between adjacent ones. Backup roll II is placed above and below the work roll row.
, 12 are arranged. Strip S is work ct-
A, 2...Curve nK is rolled in each rolling pass P1...Pn'VC in a state where it is wound approximately semicircularly.

In the above role configuration, the work role...
...The surface roughness (root mean square roughness) of the roll surface of n+1 is R1+ R2...Rn+
If it is 1, then Rn+1〉Rn〉...〉The roll surface is processed so that it is bright.

It is desirable that the difference in surface roughness between adjacent work rolls is 0.01 μm or more. If the difference in surface roughness between the two work rolls is too small, there is a risk that the strip will sag. On the other hand, if the difference in surface roughness is too large, the surface roughness of work roll n+n+1 on the exit side of the rolling mill will be extremely rough, which will impair the surface quality of the product strip.

The difference in surface roughness (J) is determined by the required surface quality.

FIG. 2 is a diagram illustrating an example of the relationship between the surface roughness of the work roll, the rolling reduction ratio, and the slack of the strip. The rolls of the test rolling mill were arranged to form three rolling baths, and the surface roughness of each work roll is shown in Table 1.

Table 1 Further, rolling conditions are shown in Table 2.

As is clear from Table 2, Figure 2, in the case of Control Examples (A) and (B), the strip sagged relative to the work roll when the rolling reduction was 60% or less. On the other hand, in the case of the present invention, sagging of the strip occurs after the rolling reduction exceeds 70%.

[Brief explanation of drawings]

Fig. 1 is a drawing schematically showing the arrangement of rolls in one-stand multi-pass rolling, and Fig. 2 shows the roll surface roughness,
FIG. 3 is a diagram showing the relationship between the rolling reduction rate and the occurrence of strip sag. 1.2~n 1+ n+ 21~24... Work roll, 11, 12... Backup roll

Claims (1)

[Claims] A method in which multiple work rolls are arranged, a metal strip is wound around the work rolls so that the metal strip is continuously rolled, and the strip is rolled between a pair of adjacent work rolls. A strip rolling method characterized in that a strip is rolled by a work roll whose surface roughness becomes progressively rougher as the side edge becomes 9Vc.