JPH02125816A - Method for heating multi-layers clad steel plate - Google Patents

Abstract

PURPOSE:To enable rolling, in which reversed machine between a heating furnace and a rolling mill is not needed by laying multi-layers clad steel plate on the specific shaped dummy slab and heating these in a heating furnace at the time of heating the clad steel plate composed of different kinds of metals differing in coefficients of linear expansion and deformation resistance. CONSTITUTION:At the time of heating the clad steel plate 1 composed of a base steel plate 1A having the small coefficient of linear expansion and a clad steel material 1B having the large coefficient of linear expansion for hot rolling, the clad steel plate 1 is warped with the difference between the coefficients of linear expansion in both composed materials and can not be bitten into rolls in the rolling mill 11. In order to prevent this defect, after heating in the heating furnace 8 while directing the clad material 1B having the large coefficient of linear expansion in the clad steel plate 1 downward and laying on the dummy slab 3 having only width size narrower than the clad steel plate 1, the clad steel plate 1 and the dummy slab 3 are separated by utilizing a stopper 9C. Then, by sending to the rolling mill 11 and rolling after removing scale on the face and rear of the clad steel plate 1, the clad plate 1 is bitten into the rolls in the rolling mill 11 and can be rolled without needing the reversed machine between the heating furnace and the rolling mill.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for heating a multi-clad steel plate such as two or three layers made of different metals having different linear expansion coefficients and deformation resistances.

[Prior art and problems to be solved by this invention] Usually,
When manufacturing a clad steel plate made by bonding dissimilar metals (for example, ordinary steel and stainless steel) using the roll rolling method, in order to ensure the bonding of the mating surfaces, first the base material and the mating material are overlapped, and the periphery is Clad materials are assembled by welding. When the clad material assembled in this manner is heated and then rolled, warping occurs due to differences in linear expansion coefficient during heating and due to differences in deformation resistance during rolling.

As shown in Fig. 6, when heating is performed with the laminate material IB having a large coefficient of linear expansion on the bottom surface and the base material IA having a small coefficient of linear expansion on the top surface, warping occurs and the laminate material 1B becomes wavy. As a result, heating becomes impossible.

On the other hand, if a laminate material with a large coefficient of linear expansion is used as the top surface, the above problem will not occur, but if this laminate material has a larger coefficient of linear expansion and deformation resistance than the base material, or if the coefficient of linear expansion is small but The laminate material with greater deformation resistance has less elongation and upward warpage occurs. If the warpage becomes large, it will not get caught in the rolls and eventually rolling will become impossible.

Therefore, conventionally, as shown in FIG. 7, the laminated material IB, which has a large deformation resistance during rolling, is placed on the bottom surface, and during heating,
A dummy slab 2 was placed underneath to prevent trouble during heating and to ensure bite during rolling (downward warping is easier to bite than downward bending).
.

However, in such a method, the dummy slab 2
Because the dimensions of the steel sheet were larger than those of the clad steel sheet, the heating time was longer and the fuel consumption rate was significantly worse.

Furthermore, Japanese Patent Application Laid-open No. 174287/1987 discloses a method in which rolling is performed by heating the laminate with the top surface without using a dummy block, and then inverting the material with a reversing machine installed between the heating furnace and the rolling mill. Although this method has been proposed, if the equipment is to be remodeled on a large scale and the size of the clad steel plate is reduced, a hatch furnace will be used for heating, which poses the problem of considerable restrictions.

This invention was made in view of the above-mentioned circumstances, and its purpose is to enable rolling without the use of a reversing machine, and to enable continuous heating of small-sized field clad steel plates, as well as to An object of the present invention is to provide a method for heating a multilayer clad steel plate that can shorten the heating time compared to a dummy slab.

[Means to solve the problem]

In the conventional heating method using a dummy slab, the width and length of the dummy slab are larger than the clad steel plate, and the heating time is longer. Therefore, in the present invention, as shown in Figs. , using a dummy slab 3 whose width remains the same but whose width is narrow, and on top of this dummy slab 3,
A two-layer clad steel plate 1 with a laminate material IB having a large linear expansion coefficient on the bottom surface is placed on the plate and continuously heated in a continuous heating furnace 8.

Furthermore, if descaling is performed with the dummy slab 3 laid down after extraction from the heating furnace, the entire back surface of the clad steel plate 1 cannot be descaled and many back surface defects occur. After extraction, as shown in FIG. 4, the two-layer clad steel plate 1 and the dummy slab 3 are separated, and then the front and back surfaces of the two-layer clad steel plate 1 are descaled and then rolled by a rolling mill 11.

The dummy slab separating device 9 (see FIG. 5) is mounted on a support frame 9.
It is possible to use a device consisting of a hydraulic or mechanical drive device 9B disposed at the center of the upper part of the body, and a stopper 9C that is moved up and down by the drive device 9B. Normally, the stopper 9C is raised and retracted, and the stopper 9C is lowered and separated only when manufacturing a clad steel plate.

In the separation operation, the stopper 9C is applied to the end of the clad steel plate 1 and the dummy slab 3 is transferred by the transfer table (see Fig. 4 (B)), and the clad steel plate 1 is separated from the top of the dummy slab 3. It is done by

Note that the descaling device 10 is a device consisting of a commonly used high-pressure water nozzle header.

[Function] By using the dummy slab, even small slabs can be transported and heated in the walking beam type continuous heating furnace 8 having the skid 4 and the skid pocket 5 without any particular problem. Furthermore, since the width is narrower than that of conventional dummy slabs, heating efficiency is improved and fuel consumption can be reduced.

When removing the dummy slab, as shown in FIG. 3, since the dummy slab 3 is narrower than the clad steel plate 1, side guides 7, which are ancillary equipment of the rolling mill 6, can also be used. That is, by holding the clad steel plate 1 between both sides by the side guides 7 and rotating the rollers of the roller table to run the dummy scrub 3 in the opposite direction to the rolling mill 6, the clad steel plate 1 is removed from the dummy slab 3. be separated.

Thereafter, the clad steel plate 1 is released from the side guide 7 and sent to rolling [6], and the dummy slab 3 is returned to the entrance side of the heating furnace and used repeatedly.

Note that if the clad steel plate 1 is separated from the dummy slab 3 by the dummy slab separation device 9 before the descaling device 10, the entire back surface can be completely descaled, and defects on the back surface can be eliminated to improve quality. Can be done.

In this way, if the dummy slab separation device 9 is installed before the descaling device 10, the dummy slab 3 can be narrower or wider than the clad steel plate 1. The heating efficiency of No. 1 is improved, and the fuel consumption rate can be reduced.

〔Example〕

This is done by making the length of the steel plate longer than the maximum size clad steel plate and using a dummy slab narrower than the width of the steel plate.
This is an example of heating clad steel plates of various sizes, and the results shown in the following table were obtained.

As is clear from this table, rolling is possible without a reversing machine, and the clad steel sheet can be put into a furnace regardless of its size. Small slabs are subject to Hatsuchi furnaces, and T/Hr and batch furnace rotation are extremely deteriorated, but by using dummy slabs, most of them can be placed in continuous processing furnaces, reducing overall fuel consumption and significantly improving delivery times, etc. It is possible to make significant improvements.

It is particularly effective for small-lot, multi-product clad steel sheets.

Note that if descaling is performed after separating the clad steel plate 1 and the dummy slab 3 using the dummy slab separation device 9,
The quality of the clad steel plate 1 can be improved by eliminating back surface flaws.

〔Effect of the invention〕

As mentioned above, in the heating method of the present invention, a metal with a larger coefficient of linear expansion is placed on a dummy slab narrower than the clad steel plate and heated in a continuous heating furnace, so there is no need to use an inverter. It is possible to roll even small-sized clad steel plates, and continuous heating is also possible.

Furthermore, since a dummy slab with a narrower width than the conventional dummy slab is used, the heating time can be shortened, and the fuel consumption rate can be reduced. Furthermore, when this narrow dummy slab is used, the clad steel plate and the dummy slab can be separated even by using the existing side guides, so the work efficiency can be further improved.

On the other hand, after extraction from the heating furnace, the multilayer clad steel plate and the dummy slab are separated, and then the front and back surfaces of the separated multilayer clad steel plate are descaled and then rolled to prevent the occurrence of defects on the back side of the clad steel plate. Can be done. Therefore, the quality of the multilayer clad steel sheet can be improved.

[Brief explanation of the drawing]

1 and 2 are a side view and a plan view showing the implementation state of the heating method of the present invention, FIG. 3 is a plan view showing the situation before rolling, and FIGS. 4(A) and 4(B) 5 is a heating process diagram and a heating process schematic operation diagram showing the heating method of the present invention.
The figure is a schematic side view showing a dummy slab separation device used in the heating method of the present invention, and FIGS. 6 and 7 are side views showing the heating state of a conventional clad steel plate. 1... Clad steel plate, IA... Base material, IB... Laminated material, 2゜3... Dummy slab, 4... Skid,
5... Skid button, 6... Rolling machine, 7... Side guide, 8... Continuous heating furnace, 9... Dummy slab separation device, 9Δ... Support frame, 9B... Drive Equipment, 9C...Stomper, 10...Descaling IJ device, 11...Rolling mill. Figure diagram

Claims (2)

[Claims] (1) In a method for heating a multilayer clad steel sheet made by joining dissimilar metals with different coefficients of linear expansion and deformation resistance, a dummy slab having a width narrower than the width of the multilayer clad steel sheet is heated before being charged into a continuous heating furnace. A method for heating a multilayer clad steel plate, comprising placing a multilayer clad steel plate with a metal having a larger coefficient of linear expansion facing downward, and heating the multilayer clad steel plate on a narrow dummy slab. (2) In the heating method for multi-layer clad steel sheets made by joining dissimilar metals with different coefficients of linear expansion and deformation resistance, the metal with the larger coefficient of linear expansion is placed on top of the dummy slab before charging it into the continuous heating furnace. Place the multilayer clad steel plate on the bottom side,
The multilayer clad steel plate on the dummy slab is heated and extracted from the heating furnace, the multilayer clad steel plate and the dummy slab are separated, and then the front and back surfaces of the separated multilayer clad steel plate are descaled, and then rolled. A method for heating a multilayer clad steel plate, characterized by: