JPS63119904A - Cropless rolling of shape steel - Google Patents

Abstract

PURPOSE:To prevent the generation of a crop crack at the front and back end of a rolled shape steel by causing a projecting part at the front and back end part of a stock with the rolling reduction of the center part in the stock width at the rolling initial time and performing the rolling reduction from the width direction by turning the stock. CONSTITUTION:In the hot rolling of the shape steel with a bloom and slab as the stock only center part in the stock width is subjected to a rolling reduction at the rolling initial time and a projecting part 10 is caused at the front and back end parts of the stock. The rolling reduction is then performed by turning the blank by 90 deg. from the width direction. With the method the crop shape 9 without any crack at the front and back ends of a rolling material is obtd. even after the plate passing of the final groove. Consequently the crop cutting-off becomes unnecessary and the yield of a shape steel product can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention aims to improve the yield by rolling the product to a short crop length in hot rolling of section steel. This relates to a cropless rolling method.

(Prior art) Rolling of section steel made of CG (continuous casting) material requires manufacturing a wide variety of products from blooms with a mono-sized cross section as shown in Figure 3.For example, H section steel In the case of rolling, as shown in the hot rolling process diagram of FIG. 6, the roll is rolled into a shape suitable for the intermediate universal rolling mill 3 by performing multiple bus rolling in the roll hole mold of the breakdown rolling 41!2. . Then universal rolling mill 3. After intermediate rolling of multiple buses using Etsuzier rolling mill 4, finishing universal rolling 41
! 5 is rolled into an H-beam by one bath.

The roll hole shape of this breakdown rolling mill is shown in (a), (b), (c), (d), (ne), and (f) in FIG.

Table 1 shows an example of a bus schedule for a breakdown rolling mill when rolling H100x 100.

Table 1 When rolling a small size as shown in Table 1, it is necessary to roll down the wide side first.
The cropped shape of the front and rear ends of the rolled material after four passes through the hole pattern (a) is a shape with a concave central portion as shown in 6 of FIG. 5 (a). Furthermore, as the number of passes increases, the top and bottom of this part overlap, and the final hole shape of the breakdown roll becomes the shape shown in 7 in Figure 5 (b).
The length of the crack due to the overlap of the cropped parts 2 is: 100
am, and in the final product, the cracks in the front and rear cropped portions are each 2.5 meters long. Due to this crop cracking at the front and rear ends, misrolls occur, and the flange collapses on the horizontal roll side of the universal roll.
Seizing occurred on the rolls, and it was often necessary to stop rolling to clean the seized rolls. For this reason, in order to prevent misrolls and roll seizures with the universal rolls, operations were carried out by cutting the front and rear ends of the breakdown material with a 400mm cut, even though the yield would deteriorate.

Further, as a measure to prevent this crop cracking, Japanese Patent Application Laid-Open No. 59-4910 has been considered. This example is a method of suppressing cropping at the front and rear ends of the sheet bar by controlling the amount of cropping at the front and rear ends of the rolled material using a press preforming device installed at the front of the rolling mill.

(Problems to be Solved by the Invention) In order to reduce the cracking of the cropped portion due to the overlapping of the front and rear ends of the rolled material, we tried a method of lightly rolling the material using the hole shape shown in Figure 4 (a). However, the effect was small, and the rolling force (T/11) decreased due to the increase in the number of baths, so no drastic measures were taken.

The present invention is a rolling method that solves these drawbacks, and aims to prevent crop cracking at the front and rear ends of the rolled material by overfilling the special roll hole shape before starting blocking rolling. .

Also, in the method in JP-A-59-4910,
Is it possible to control the crop amount?The present invention attempts to prevent crop cracking using the roll hole type of a conventional rolling mill without using a press preforming device.

(Means for solving the problem) The present invention improves the crop shape of the front and rear ends of the rolled material by arranging a specially shaped hole in front of the conventional box hole type of the breakdown roll. It is the law.

That is, the configuration of the present invention for achieving the above object is as follows. That is, in hot rolling of section steel using blooms and slabs as raw materials, the central part of the width of the material is rolled down at the beginning of rolling to create convex portions at the front and rear ends of the material, and then the material is rolled at a 90° angle. It is characterized by turning and rolling down from the width direction,
This is a cropless rolling method for section steel.

The details of the present invention will be explained below with reference to the drawings.

FIG. 1 is a diagram showing a roll hole shape according to the present invention.

B in Figure 1 (g) is approximately the same as the hot dimension of the material,
A depression of dimension d is formed in the center of the rolled material. In addition, in order to stably roll only the central portion, 2Xd+H is made the same as the hot dimension of the material. (A) to (F) in FIG. 1 are the same as the conventional hole shapes. Table 2 shows an example of the bus schedule for a breakdown rolling mill when rolling 1100 xlOO.

By rolling down only the center part to a depth of 40 m + ■ using the hole shape shown in Table 2, Figure 1 (G), the tongue is brought out in advance only at the center of the front and rear ends of the rolled material, and then the next hole shape (I ). The shape of the front and rear ends of the fourth pass at this time is 8 in Figure 2 (A).
As shown in FIG. 1, the central part of the material is rolled down using the hole mold shown in FIG.

Therefore, even in the final hole shape of the breakdown, as can be seen from the crop shape shown by 9 in Fig. 2 (b),
No crop cracks were observed at the front or rear ends of the rolled material, and of course crop cracks in the final product were also eliminated.

(Effects of the Invention) By carrying out the present invention, the amount of crop truncation at the front end of the rolled material after breakdown rolling was able to be significantly reduced, and crop truncation at the rear end of the rolled material became unnecessary. As a result, we were able to improve the yield by 3%, as well as completely eliminate roll misrolls and roll seizures caused by crop cracks at the front and rear ends, significantly improving the work rate.
The fuel consumption rate has been significantly improved, and the effects are significant.

[Brief explanation of the drawing]

Figures 1 (a) to (g) are diagrams showing the groove shapes for cropping rolled material according to the present invention, and Figures 2 (() and (0) are views during rolling when using the cropless groove. Figure 3 is a cross-sectional view of the frame, Figures 4 (A) to (F) are views showing the conventional hole shape, Figure 5 (A),
(II) is a diagram showing a crop shape in the case of the conventional rolling method, and FIG. 6 is a diagram of the conventional hot rolling process. 1... Bloom, 2... Breakdown rolling mill, 3
... Intermediate universal rolling mill, 4. Edger rolling mill, 5. Finishing universal rolling mill, 6. ) is the crop shape after the appropriate material is used, 8... (a) the entire crop shape after the hole type is appropriate material, 9-(f) is the crop shape after the hole type is appropriate material, 10... (i) )) The shape of the crop tip after adjusting the hole shape.

Claims (1)

[Claims] In hot rolling of section steel using blooms and slabs as raw materials, the central part of the width of the material is rolled down at the beginning of rolling to create convex portions at the front and rear ends of the material, and then the material is turned 90°. Characterized by rolling down from the width direction,
Cropless rolling method for section steel.