JPS60206505A - Continuous cold rolling method - Google Patents

Abstract

PURPOSE:To prevent the breakage of the welded part of a rolling steel strip by detecting the weled part at the inlet side of a rolling mill and reducing each interstand tension and a rolling speed to prescribed rates respectively, in a continuous cold tandem rolling by mutually welding the coil ends of steel strips. CONSTITUTION:The rear end of a preceding steel strip and the front end of a succeeding steel strip 1 are mutually welded 3 without changing a rolling speed by using a loop car 4. When the welded part is detected by a detector 9. a control device 10, which is actuating a speed meter 8 and a constant-tension control device, reduces the tension of each stand and the rolling speed by a motor M to the prescribed rates respectively. Thus, an unreasonable tension is not burdened on the welded part during the continuous rolling of welded part, and the welded part of steel strip is prevented from being broken by tension. Accordingly, the cold rolling can be continuously operated in a stable state.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial Application Field The present invention relates to a continuous cold rolling method for copper strips.

(b) Prior art In recent years, the ends of copper strip coils are successively joined by welding.
A continuous cold rolling method has been developed in which rolling is performed continuously using a tandem rolling mill. However, when the welded joint of the copper strip passes through a tandem rolling mill, the welded joint frequently breaks. However, in previous performances, the rolling speed was reduced to approximately the threading speed (100 to 2001 R/1ill) simply to minimize mill trouble at the time of breakage.

(C) Object of the Invention The object of the present invention is to prevent the welded joint of a copper strip from being broken due to excessive tension when it passes through a tandem cold rolling mill during continuous cold rolling.

(Second Structure of the Invention) The cold rapid continuous rolling method of the present invention is a method in which the ends of a copper strip coil are sequentially welded to each other and the copper strip is continuously rolled in a tandem cold rolling mill. d5 on the entry side of the cold rolling mill to detect the passing of the welded joint of the copper strip, and to adjust the set interstand tension of the cold rolling mill as the welded joint passes through the cold rolling mill; It consists of avoiding reduction by a predetermined ratio.

The above method can also be modified as follows.

Furthermore, the passage of the welded joint of the steel strip is detected on the entrance side of the cold rolling mill, and the running speed of the copper strip is also detected, and when the welded joint passes through the cold rolling mill, The set interstand tension of the cold rolling mill may be reduced by a predetermined ratio, and the rolling speed of the cold rolling mill may be reduced by a predetermined ratio.

The method of the present invention will be explained with reference to FIGS. 1 and 2. FIG. 1 shows a schematic configuration of a continuous cold rolling facility to which the method of the present invention is applied. The steel strip 1 is fed out from the payoff reel 2, and the rear end of the leading steel strip and the leading end of the trailing steel strip are butted and welded by welding 1113. To facilitate the detection of welded joints, it is preferable to drill holes in the joints. The steel strip 1 is guided to a tandem cold rolling mill 5 via a loop car 4, subjected to a predetermined rolling process, cut by a running shear 6 at a temperature of 0.degree. C., and wound onto a take-up reel 7.

Tandem cold rolling 1II5 usually uses a constant tension control system @5
The tension is controlled by 1.

A speed meter (PLO) 8 and a welding point detector 9 are provided on the entry side of the tandem cold rolling mill 15. Speedometer 8 is steel strip 1
detects the traveling speed of the vehicle and inputs the detection signal to the control device 10. Welding point detector 9 detects passage of the steel strip 1 through a welded joint, and inputs each detection signal to control device 10 .

A reduction rate α of the set tension of the steel strip 1 in the tandem cold rolling mill 5 and a reduction rate β of the set speed of the steel strip 1 in the tandem cold rolling mill 5 are input to the control device 10 as set values. .

The output of the control device 10 is input to the drive motor M of each stand of the tandem cold rolling fM5 and the tension constant control device 51.

The method of the present invention is characterized in that when a weld joint of the steel strip 1 is detected on the entry side of the tandem cold rolling mill 5, the control device ξ10 changes the tension saw target value in the constant tension control. And T.

Avoid decreasing by a certain ratio α. Therefore, the tension TI after the change is expressed by the following formula <1>.

1−+=1−o(1−α) −−−−−−(+) The welded joint of the steel strip 1 is tracked in the tandem cold rolling mill 5, and the welded joint is , the tension target value is set to the initial setting value T. Return it to a tapered shape (gradually) so that it looks like this. Furthermore, tandem cold rolling mill 5
The set rolling speed V0 may be decreased by a predetermined ratio β. In this case, the control device 10 sends a control signal to the drive motor M of each stand to reduce the rolling speed.

The rolling speed v1 after the change is expressed by the following equation (2).

V+=Vo (1-β), -------<21 The above-mentioned tension and rolling speed reduction control is shown in a graph as shown in FIG.

The above-mentioned control was performed for welding the steel strip on the entry side of the tandem cold rolling mill-5, but the same control as described above is also possible for the coil 2o welded on the entry side of the pickling line. be. However, in this case, since the welding joint position is already known as coil information, there is no need to detect the welding joint position anew if the coil information is input into the control device 110 in advance.

It is preferable that the tension reduction rate α is set to 10% to 30%. The reason is that, as shown in FIG. 3, as the tension reduction rate α (%) increases, the number of weld fractures also decreases. However, if α exceeds 30%, fluctuations in tension will have an adverse effect on the thickness accuracy of the copper strip, and troubles in squeezing will occur due to a decrease in tension. On the other hand, if α is less than 10%, the effect will not be much improved.

Further, it is preferable that the rolling speed reduction rate β is set to 50 to 70%. The reason is that during rolling work at high speed,
This is because if the welded joint breaks, the extent of scrap generation, roll damage, etc. will be significant, but this will not adversely affect the unit consumption, yield, or efficiency.

(B) Example 1 Rolled to 11 m. The set tension T at this time. 20t
on, and the set rolling speed V0 was set to 1200 m 2 /min. The tension reduction rate α was increased by 30%, and the rolling speed reduction rate β was increased by 30%.
was set at 66%.

As a result of applying the method of the present invention to 300 coils under the above conditions, there was only one weld breakage.

(f) Effects According to the method of the present invention, the number of weld fractures can be reliably reduced without reducing the plate thickness accuracy of the finished product.

[Brief explanation of drawings]

FIG. 1 is a schematic explanatory diagram of an apparatus that can carry out the method of the present invention. FIG. 2 is a graph illustrating the invention in detail. FIG. 3 is a graph showing the effect of an embodiment of the method of the present invention. 1... Steel strip 2... Payoff reel 3... Welding I
! ! ' 4... Loop car 5... Tandem cold rolling m- 6... Running shear 7... Take-up reel 8... Speed meter (LPG) 9... Welding point detector 10 ... Control device 20 ... Coil 51 ... Constant tension control device Patent applicant Sumitomo Metal Industries, Ltd. (4 others)

Claims (2)

[Claims] (1) In a method in which the ends of a steel strip coil are sequentially welded to each other and the strip is continuously rolled in a tandem cold rolling mill, the welded joint of the steel strip is formed on the entry side of the cold rolling mill. and reducing the set interstand tension of the cold rolling mill by a predetermined ratio as the welded joint passes through the cold rolling mill. (2) In a method in which the ends of copper strip coils are sequentially welded to each other and the copper strips are continuously rolled in a tandem cold rolling mill, the welded joints of the copper strips are formed on the entry side of the cold rolling mill. detecting the running speed of the steel strip at the entry side of the cold rolling mill; and detecting the running speed of the steel strip at the entrance side of the cold rolling mill; A continuous cold rolling method comprising reducing the tension by a predetermined ratio and reducing the rolling speed of the cold rolling mill by a predetermined ratio.