JPS62127162A - Production of steel ingot - Google Patents

Abstract

PURPOSE:To improve the yield in the rolling stage of an ingot in a hot top method by solidifying the unsolidified to part of the molten steel in a casting mold to a flat shape while supplying and moving a heat source such as arc to said top part. CONSTITUTION:The molten steel poured from a ladle passes a runner and enters the casting mold 1 from an inflow port 3 of a molding board 2 and while the molten steel fills the inside of the casting mold from the lower side, the molten steel surface rises. The casting operation ends when a prescribed amt. of the molten steel is poured into the mold. The heat source such as arc is immediately or quickly supplied to the unsolidified top part. For example, an arc bar 4 is fixed to a supporter 5 and the supporter 5 is connected to a position control mechanism 6 so that the bar 4 is spirally moved and lowered in the case of arc heating. The arc from the bar 4 is allowed to contact the inside wall of the casting mold 1 so as to start heating the molten steel from the periphery of the edge part where the solidification is fast. The heating point is spirally moved toward the central part as the solidification progresses toward the central part.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to the production of steel ingots (ingots), and more particularly, to an ingot production method that enables improved yield during ingot rolling.

(Prior Art and Problems) In recent years, continuous casting technology has made remarkable progress, replacing the conventional process of ingot casting and blooming rolling, and making it possible to mass produce slabs at low cost.

However, conventional processes are still indispensable for production of specific steel types or relatively small quantities, and with the development of continuous casting technology, more and more economical efficiency is required.

Therefore, for example, attempts have been made to reduce the occurrence of fishtails by applying a light reduction from the side to the top part during blooming of the ingot, in order to improve the yield, and some results have been achieved. but.

This rolling method requires special equipment and has problems such as reduced rolling efficiency.

On the other hand, during ingot ingot making, after pouring molten steel into the mold, heat-generating powder is immediately supplied to the head of the ingot to keep the feeder warm, thereby reducing the number of cut-off parts such as pipes formed on the ingot top. However, since exothermic powder uses thermite reaction to supply heat, it is not sustainable, there are restrictions on the powder supply period, and there is an environment where dust is generated due to the thermite reaction. There is a problem of contamination.

(Object of the Invention) The present invention solves the drawbacks of the above-mentioned conventional techniques regarding ingot ingot making, effectively heats the unsolidified head in the mold to solidify the head into a flat shape, and thereby enables ingot rolling. It is an object of the present invention to provide a method for manufacturing an ingot that can improve the yield.

(Structure of the Invention) In order to achieve the above object, the present invention was made as a result of studies on a hot top method that is cleaner and can control the working time. In view of the fact that solidification progresses from the edge on the inner wall side of the mold, a heat source such as an arc is sequentially moved from the edge to the center according to the progress of solidification to heat the mold in a spiral manner. It is.

The present invention will be explained in detail below based on examples.

FIG. 1 is a diagram showing an arc heating device and heating method used in carrying out the present invention.

In the figure, 1 is a mold, 2 is a surface plate, and the surface plate 2 has an inlet 3 for injecting molten steel into the mold 1 from a runner (not shown).
is provided. In addition, the casting V2ffl including these mold 1, surface plate 2, and ingot forming method are the same as conventional ones,
Molten steel poured from the ladle passes through a runner and enters the mold 1 from the inlet 3 of the surface plate 2.

The mold is filled from below and the level rises, and when a predetermined amount of molten steel has been poured, the spinning operation is completed.

In the present invention, a heat source such as an arc is supplied to the unsolidified head immediately or promptly after the casting is completed. As a heat source, in addition to arc, gas (eg, acetylene gas), plasma arc, etc. can be used, and an appropriate heating means is selected in consideration of the size of the ingot, the amount of heat, etc.

FIG. 1 shows an arc hot top using arc heating. The arc rod 4 is fixed to a support A5, and the support 5 is connected to a position control mechanism 6.
The arc rod 4 is configured to move in a spiral manner and descend.

That is, the arc from the arc rod 4 starts heating the molten steel from around the edges where it contacts the inner wall of the mold 1 and solidifies quickly, and as the solidification progresses toward the center, it heats the molten steel in a spiral shape toward the center. Move the point. At this time, 1, the molten steel in the mold contracts as solidification progresses, and the molten metal level at the head of the mold decreases, so the arc rod 4 is lowered according to the degree of contraction. By supplying arc heat to the unsolidified portion as the head solidifies in this manner, it is possible to sufficiently replenish molten steel from the edge portion to the center portion, and the head portion can be solidified into a flat shape.

Although we have shown the case where an arc rod is used as the heating source, it can be similarly applied to cases where other gases are used as the heating source, and it can be applied not only to bottom pouring ingots but also to top pouring ingots. Needless to say, it can be applied.

(Example) A 7-ton ingot was manufactured by the bottom pouring ingot method using the casting apparatus shown in FIG.

At that time, 1. Immediately after finishing the casting, arc heating (for 60 minutes) was applied to the head part in a spiral manner from the edge part. For comparison, exothermic powder was supplied to the head immediately after the casting was completed.

Each of the obtained ingots was subjected to blooming rolling using a conventional method, and the amount of cut-off was examined. The yield was 87% in the conventional method using exothermic powder, but the yield was 89% in the method of the present invention. I was able to improve it.

(Effects of the Invention) As explained above, according to the present invention, heat is supplied to the unsolidified head in the mold using a clean heating source such as an arc, and as the solidification progresses, the heat is supplied to the unsolidified head in a spiral shape as solidification progresses. Since the ingot is supplied, it is possible to manufacture an ingot having a flat head, and therefore it is possible to improve the yield during ingot rolling. Furthermore, since a clean heating source such as an arc is used, there is no problem of environmental pollution, and furthermore, workability is good.

4. Brief description of aspects FIG. 1 is an explanatory diagram showing an arc hot top method according to an embodiment of the present invention.

1...Mold, 2...Surface plate, 3...Inflow port, 4...Arc rod, 5...Support,
6...Position control mechanism.

Patent applicant: Daido Steel Co., Ltd. Representative Patent Attorney Takashi Nakamura Figure 1

Claims (1)

[Claims] When pouring molten steel into the mold and solidifying it, after the pouring into the mold is finished, a heat source such as an arc is supplied to the top in an unsolidified state in a spiral shape from the edge to the center, and the steel is solidified. A method for manufacturing a steel ingot, characterized by forming a flat top.