JPH07155818A - Method for rolling for reversible rolling mill - Google Patents

Abstract

PURPOSE:To prevent a surface folding generating in the intermediate part of a belt-like material at the time of taking-up by gradually increasing a drawing down force at the time of a rolling start in an initial pass to gradually decrease the change of a thickness, gradually decreasing a drawing down force at the time of the completion of rolling to gradually increase the change in the thickness at a tip part at the time of the completion of rolling. CONSTITUTION:At the time of the start of the rolling of each pass, the total drawing down quantity (t0 - t1) of the pass, is gradually added to the intermediate part on one end side of a belt-like material existing between an upper and a lower rolling rolls, and the change of a thickness at the tip part of a rolling start, is allowed to gradually reduce in a tapered shape or by stages. Further at the time of the completion of each pass, the total drawing down quantity (t0 - t1) of the pass, is gradually released from an intermediate part on another end side of the belt-like material existing between the upper and the lower rolling rolls, the change in the thickness at the tip part of a rolling completion, is allowed to gradually increase in a tapered shape or by stages. Consequently, a difference in level in rolling, generating at the tip part of the rolling start of the belt-like material and at the tip part of the rolling completion, can be adjusted so that it becomes within an allowable difference in level in which the surface folding is not generated at the time of taking-up, and the surface folding caused by the difference in level in rolling, can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling method for a reversible rolling mill.

[0002]

2. Description of the Related Art Conventionally, in a reversible rolling mill, winding devices are arranged on both sides of the rolling mill, and the strip material is reversible in a state in which both ends of the strip material are wound around the mandrels of the respective winding devices. Roll multiple passes.

[0003]

However, in the prior art, at the start of rolling of each pass, the intermediate portion of the strip-shaped material located between the upper and lower rolling rolls near one end (a few windings from one winding end on the mandrel of the winding device). The total amount of reduction (t ₀ -t ₁ ) of the pass is added to the (separated portion) at once (FIG. 4 (A)), and at the end of rolling of each pass, the intermediate portion (the mandrel of the winding device of the winding device) near the other end of the strip-shaped material (The part which is separated from the other end by several turns) is released all at once. Therefore, the strip-shaped material has a rolling step as shown in FIG. 4 (A) at the intermediate portion near the one end and the intermediate portion near the other end. And, this step is, when the strip-shaped material is wound on the winding device as the rolling progresses,
This causes surface bending in the range of several turns to several tens of turns in the middle part of the strip-shaped material (FIG. 4 (B)). The occurrence of this breakage is
This becomes remarkable because the winding tension also becomes large when rolling a stainless steel plate having a large rolling tension.

In Japanese Patent Laid-Open No. 2-263515, when a strip-shaped material is wound around a mandrel, the step formed by the tip of the strip-shaped material with respect to the outer surface of the mandrel is several to several tens of windings of the strip-shaped material. In order to prevent the generation of the top mark caused by the transfer to, the mandrel is proposed to have a stepped sleeve. However, the above-described surface breakage during reversible rolling is caused by a rolling step that occurs in the intermediate portion of the strip-shaped material, and the above-mentioned Japanese Patent Laid-Open Publication No. The technique described in Japanese Patent No. 2-263515 cannot solve the problem at all.

It is an object of the present invention to prevent surface breakage due to a rolling step that occurs in the intermediate portion of a strip-shaped material when the strip-shaped material to be reversibly rolled is wound.

[0006]

SUMMARY OF THE INVENTION According to the present invention, a winding device is arranged on both sides of a rolling mill, and both ends of the strip are wound around a mandrel of each winding device. In the rolling method of the reversible rolling mill that performs multiple pass rolling in
At least in the initial pass of each pass, the rolling force at the start of rolling is gradually increased to gradually reduce the plate thickness change at the rolling start end, and the rolling force at the end of rolling is gradually reduced to reduce the rolling end end. The change in plate thickness of the part is gradually increased.

[0007]

[Operation] At the start of rolling in each pass, the strip is gradually moved to an intermediate portion between the upper and lower rolling rolls, close to one end of the strip (a part separated from the one end of winding on the mandrel of the winding device). The total reduction amount (t _o −t ₁ ) of the pass is applied to, and as a result, the plate thickness change at the rolling start end can be gradually reduced in a taper or step shape.

At the end of rolling in each pass, the strip-shaped material is separated from the other end of the strip-shaped material between the upper and lower rolling rolls by an intermediate portion (several windings from the other end of winding on the mandrel of the winding device). (Part) gradually decreasing the total amount of the pass (t ₀ −t ₁ ).
As a result, the plate pressure change at the end of rolling can be gradually increased in a taper shape or a step shape.

This makes it possible to adjust the rolling step generated at the rolling start end and the rolling end end of the strip during rolling in each pass so as to be within the allowable step which does not cause surface bending during winding, and the rolling step It is possible to prevent the bending of the surface.

In reversible rolling, although a rolling step is generated in all passes, the initial pass of all passes is
(a) Since the pre-rolling plate pressure T ₀ is large even if the reduction ratio is the same,
Since the amount of reduction (t ₀ −t ₁ ) is large and (b) the reduction ratio is set to be large compared to the post-pass where the material to be rolled is work hardened, the rolling step becomes large. Therefore, the present invention is particularly effective when implemented on the initial path side among the paths.

[0011]

1 is a schematic diagram showing a reversible rolling mill, FIG. 2 is a schematic diagram showing a tapered reduction state according to the present invention, FIG. 3 is a schematic diagram showing a stepwise reduction state according to the present invention, and FIG. It is a schematic diagram which shows an example.

The reversible rolling mill 10 has winding devices 11 and 12 arranged on both sides thereof, and both ends of the strip S are wound around the mandrels 11A and 12A of the winding devices 11 and 12, respectively. The strip S is reversibly rolled in multiple passes.

The reversible rolling mill 10 changes the gap between the upper and lower rolling rolls 14 and 15 by the reduction cylinder 13,
A predetermined amount of reduction can be applied to the strip material S.

The rolling method by the reversible rolling mill 10 will be described below. (1) Mandrels 11A, 12A of both winding devices 11, 12
Both ends of the strip-shaped material S are wrapped around each of the strips, and tension is applied to the strip-shaped material S, and rolling of each pass is started.

(2) By using the reduction cylinder 13 in at least the initial pass side of all passes or each of the passes forming all the passes, (a) the rolling force at the start of rolling can be gradually increased. The plate pressure change at the rolling end is gradually reduced, and (b) the rolling force at the rolling end is gradually increased by gradually reducing the rolling force at the end of rolling.

The gradual reduction and gradual increase control of the plate pressures (a) and (b) by the pressure reduction cylinder 13 are performed in the taper shape of FIG. 2 or the step shape of FIG.

The operation of this embodiment will be described below. At the start of rolling of each pass, the strip material S is separated from the one end portion of the strip material S between the upper and lower rolling rolls 14 and 15 (the winding device 11 is wound around the mandrel 11A by several turns). Gradually decrease to the total reduction amount (t _o −t) of the pass.
₁ ) is added, and as a result, the change in plate thickness at the rolling start end can be gradually reduced in a taper or step shape.

At the end of rolling in each pass, the strip material S
Is gradually moved from the intermediate portion near the other end of the strip S between the upper and lower rolling rolls 14 and 15 (a portion separated from the other end of the winding of the winding device 12 onto the mandrel 12A) by several passes. The total reduction amount (t ₀ −t ₁ ) is released, and as a result, the plate pressure change at the end of rolling can be gradually increased in a taper shape or a step shape.

As a result, the rolling step generated at the rolling start end and the rolling end end of the strip S during rolling in each pass is
It can be adjusted so as to be within an allowable step difference that does not cause a surface break during winding, and it is possible to prevent a surface break due to a rolling step.

The specific results of carrying out the present invention will be described below. In the reversible rolling of the stainless steel sheet, which has a large rolling tension and a large winding tension, and is likely to cause surface bending due to the rolling step, it is possible to reduce the conventional yield loss of 1% to 0.2% by implementing the method of the present invention. It was confirmed that the effect of the present invention was extremely remarkable.

[0021]

As described above, according to the present invention, it is possible to prevent the surface breakage due to the rolling step which occurs in the intermediate portion of the strip-shaped material when the strip-shaped material to be reversibly rolled is wound.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a reversible rolling mill.

FIG. 2 is a schematic view showing a tapered rolled-down state according to the present invention.

FIG. 3 is a schematic view showing a stepwise rolled state according to the present invention.

FIG. 4 is a schematic view showing a conventional example.

[Explanation of symbols]

 S Band-shaped material 10 Reversible rolling mill 11, 12 Winding device 11A, 12A Mandrel 13 Rolling cylinder

Claims (1)

[Claims] 1. A reversible rolling method in which a winding device is arranged on both sides of a rolling mill, and the strip material is reversibly rolled in a plurality of passes in a state where both ends of the strip material are wound around the mandrels of the respective winding devices. In the rolling method of the rolling mill, in at least the initial pass of each pass, the rolling force at the start of rolling is gradually increased to gradually reduce the thickness change at the rolling start end and gradually reduce the rolling force at the end of rolling. In particular, a rolling method for a reversible rolling mill characterized by gradually increasing the plate thickness change at the end of rolling.