JPS6044159A - Cutting method of continuous casting billet - Google Patents

Abstract

PURPOSE:To improve yield and to prevent decrease in rolling efficiency owing to an increase in the number of pass by cutting a continuous casting billet at the tapered recesses formed by pressing tapered indenting blades to said billet prior to solidification. CONSTITUTION:A continuous casting billet 1 is fed on a roller conveyor to a stage for forming recesses where a pair of indenting blades 2, 3 are forced by a press or the like to the billet 1 in the stage prior to solidification. The indentation is accomplished from above, below, right and left, by which tapered recesses 4 and are formed. The billet is further fed to the succeeding stage where the troughs of the recesses 4 are gas-cut by, for example, a gas cutting means 6. The recesses are formed not by rolls as in the biting back rolling method according to the above-mentioned method and therefore the recesses can be formed to desired shape and depth and the yield is additionally improved. An increase in the number of rolling pass is obviated.

Description

[Detailed description of the invention] The present invention relates to a method for continuous casting and tapering cutting of slabs.

When continuously cast slabs are rolled, defective parts, so-called crops, which must be discarded, inevitably occur at the front and rear ends due to fishtails and rolling overlaps generated by rolling.

Conventionally, single-pass rolling, double-pass rolling, back-bite rolling, etc. have been performed in order to reduce cropping and improve yield when cutting continuously cast slabs. Rolling is carried out only from one direction, either the side or the pull-out side, and the push-in and pull-out ends are concentrated in the rolled material to reduce cropping at the push-in end.In double-pass rolling, both ends of the rolled material are Although the crop is reduced at both ends by making the ends push-in, the improvement in yield is small in both single-pass rolling and double-pass rolling.

In contrast, in bit back rolling, a recess is formed at the end of the steel ingot using rolling rolls in the width direction or thickness direction, and this part is used as the handling end. This method sucks metal 70- and prevents the growth of fishtail during width reduction and rolling overlap on the thickness reduction surface, and a higher yield can be obtained compared to single-pass rolling or double-pass rolling, but the number of passes is An increase in the amount is unavoidable, and there is a problem in that the rolling efficiency decreases.

In order to improve the above-mentioned problems, the present invention has been developed to prevent the occurrence of overlap comparable to that in bit back rolling, to reduce the amount of cropping, and to improve the yield accordingly, and to improve rolling efficiency without increasing the number of passes. The object of the present invention is to provide a method for cutting continuously cast slabs that does not cause deterioration.

The method of cutting continuously cast slabs according to the present invention to achieve this objective is to press a tapered pushing blade into the continuous cast slab from above and below and from the left and right by pressing or rolling before solidification to form a tapered recess. The tapered concave portion is then cut using a press or gas cutting.

When using the above-mentioned cutting method, tapered recesses are formed in advance from the top, bottom, left and right of the continuously cast slab, thereby preventing the occurrence of overlap and fishtail. In particular, forming a taper in the left and right direction greatly contributes to preventing the occurrence of fishtails. Since this tapered recess is formed in a recess of the same size or larger as the recess in back-bite rolling, it is expected that the yield will be equal to or higher than that in back-bite rolling. Further, in forming the recesses, there is no need to reciprocate the steel ingot between rolls as in bit back rolling, so the number of passes does not essentially increase and rolling efficiency can be maintained well. Further, the method of the present invention can be applied not only to the front and rear ends of a rolled material but also to cutting in the middle in the longitudinal direction.

Preferred embodiments of the method for cutting continuously cast slabs of the present invention will be described below with reference to the drawings.

FIG. 1 shows a continuously cast slab 1 to be cut. The continuously cast slab 1 is sent to the process shown in FIG. 2 on a roller conveyor or the like.

In the process shown in FIG. 2, a pair of pushing blades 2.3 each having a tapered tip are provided and are pushed into the continuously cast slab 1 in the pre-solidification stage by a press. This pushing is performed from above, below, left and right of the continuously cast slab 1. Either of the upward and downward pushing or the left and right pushing may be done first. During pushing, the movement of the continuously cast slab 1 is stopped, but when pushing is performed while the continuously cast slab 1 is moving, the pushing blade 2.3 is also moved at the same speed. By the above-mentioned pushing, a tapered recess 4 is formed in the continuously cast slab 1, as shown in FIG.

The pushing blade 2.3 may be pushed in by rolling as shown in FIG. In Fig. 4, the pushing blade 2.
3 consists of an abacus-shaped roll, is rotatably supported by a shaft 5, and is run in the width direction of the continuously cast slab 1 to form a tapered recess. In the case of rolling, only a small pressing force is required compared to that of a press.

The continuously cast slab 1 in the state shown in FIG. 3 is further sent to the process shown in FIG. 5, where the valleys of the tapered recesses 4 are gas cut by a gas cutter 6. Gas cutting may be replaced by press cutting.

This completes the cutting.

FIG. 6 shows the cut portion 7 of the continuous casting piece 1 cut by the process shown in FIG.

When using the above cutting method, the following effects can be obtained.

First, press the blade 2.3 into the cutting position of the continuously cast slab 1 in advance.
As a result, two tapered concave portions 4 are formed from the top and bottom, left and right sides, so that the same effect as bit back rolling can be obtained, that is, the metal 70-
This prevents the formation of fishtails and the growth of over-rolling welts. In this case, since the tapered recess 4 is formed not only in the vertical direction but also in the horizontal direction, the occurrence of fishtail is effectively prevented. Therefore, a large yield can be obtained.

Note that since the recesses are not formed by rolls unlike conventional bit back rolling, the shape and depth of the recesses can be freely determined. Therefore, it is possible to select the shape of the pushing blade that is most suitable for cutting, thereby further improving the above-mentioned yield.

In addition, compared to bit back rolling, there is no need to move the continuously cast slab 1 back and forth between rolls located at the front and rear positions in the feeding direction.
The number of buses does not increase, and a decrease in rolling efficiency can be prevented.

[Brief explanation of drawings]

Figure 1 is a side view of a continuous cast slab, Figure 2 is a side view of a continuous cast slab in the step of forming a tapered recess with a pressing blade of a press, and Figure 3 is a side view of a continuous cast slab with a tapered recess formed. Figure 4 is a side view of a continuously cast slab in the process of forming a tapered recess with a rolling thrust blade, Figure 5 is a side view of a continuously cast slab in the gas cutting process, and Figure 6 is a side view of a continuously cast slab in the gas cutting process. FIG. 3 is a perspective view of the continuously cast slab after cutting. 1...Continuous casting slab 2.3...Pushing blade 4...Tapered recess 5...Shaft 6...Gas cutting tool 7... Cutting section

Claims (1)

[Claims] (1) A tapered indentation blade is pressed into the continuously cast slab from above and below, left and right by pressing or rolling to form a tapered recess, and the tapered recess is cut by pressing or gas cutting. How to cut continuously cast slabs.