JPH01181948A - Twin directional drawing type horizontal continuous casting method - Google Patents

Abstract

PURPOSE:To prevent occurrence of breakout and to improve surface characteristic of a cast billet by blowing lubricant between both side parts of the mold except the specific range at center part and the cast billet at the time of drawing the solidified cast billet from the mold. CONSTITUTION:The molten steel is poured from a tundish 4 through a feed nozzle and at the time of drawing the cast billets 12 from these both ends of the mold 6 to reverse direction into gap between both side parts of the mold 6 except range of 50-400mm at center part of the mold 6 and the solidified cast billet 12, the lubricant 28 of Ar, N2 gas, rape seed oil, graphite powder, etc., is blown. By this method, the occurrence of the breakout is prevented, and the surface characteristic of the cast billet is improved.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a bidirectional drawing type horizontal continuous casting method, and in particular to a casting method that can prevent the occurrence of breakouts and improve the surface properties of slabs. Widely used in the field of casting.

[Conventional technology]

In the field of continuous casting, instead of the conventional vertical or curved continuous casting method, a horizontal continuous casting method has been proposed in which a horizontally arranged continuous casting mold is used to pull out and cast slabs horizontally. Casting of slabs is carried out.

With these horizontal continuous casting methods, conventional vertical or curved continuous casting methods require large costs to construct buildings that reach heights of 30 to 40 meters and structures that support the large weight associated with them. On the other hand, it is attracting attention because of its advantages of being able to lower the height of the building and having relatively low equipment costs.

The horizontal continuous casting method also changed from the initial method in which the slab was pulled out from the mold to the end, to a method in which the slab was pulled out from both ends of the mold in opposite directions, as disclosed in JP-A-58-138544, and production progressed. Capacity improvements have been achieved.

This method will be explained with reference to FIGS. 5(A) and 5(B).

Below a container 4, such as a ladle or tundish, containing molten steel 2, a mold 6 is horizontally arranged with its end facing in the horizontal direction. Container 4 and mold 6 are feed nozzle 8
This allows the molten steel 2 to communicate without leakage. Mold 6
, the container N4 is vibrated left and right by the vibrating device 10, and the slab 12 in which the molten steel 2 has solidified is pulled out left and right by the pinch rolls 14.

In conventional vertical or curved continuous casting machines, the powder poured onto the surface of the molten steel in the mold melts into slag, which shrinks as a solidified shell forms and fills the gap between the mold and the inner wall of the mold. It penetrates and acts as a lubricant, but
Such lubrication is difficult in a horizontal continuous casting machine due to its structure.

The formation of the solidified shell 16 in the mold during horizontal continuous casting will be explained with reference to FIG. As shown in FIG. 6, the solidified shell 16
Ideally, the formation start position is located at the center of the mold 6, directly below the feed nozzle 8, and this is the point where the left and right slabs separate and break. However, in actual operation, an unhealthy thin solidified shell is formed in the part that is off the center and breaks from there, and when this is repeated, it gradually moves away from the center and finally the break position moves away from the mold 6 and breakout occurs. This will result in a major accident.

80% of breakouts consist of what is called a restricted breakout. This restraining breakout occurs when the solidified shell 16 is broken due to seizure between the solidified shell 16 and the mold 6, and occurs through the following process. That is, although FIG. 7(A) shows a state in which coagulation is occurring normally,
As shown in FIG. 7(B), a part of the solidified shell 16 has a burned part 1
8, a break point 20 occurs downstream thereof. A solidified shell 16 is formed at this breaking point 20 due to heat removal from the mold 6, but because it is thin, it repeatedly breaks as shown in FIG. 7(C), and finally the breaking point 20 moves away from the center and finally As shown in (D), a breakout point 20 occurs at a location where the mold 6 is removed, and a breakout occurs.

Unlike vertical or curved type horizontal continuous casting machines, the feed nozzle 8 and mold 6 are mounted closely together, so it is structurally difficult to inject lubricant during casting. Therefore, in horizontal continuous casting, there are many breakouts caused by seizure of the solidified shell 16 to the mold 6 due to no lubrication, and even when breakouts do not occur, the surface quality of the slab deteriorates. .

Conventionally, in order to prevent seizure, there has been a method of plating the inner wall of the mold with a lubricating function, or Japanese Patent Application Laid-Open No. 56-111
As disclosed in Japanese Patent No. 57, a method has been proposed in which lubricant is press-fitted by moving the mold intermittently.1. Currently, it is not possible to effectively prevent breakouts due to burn-in.

[Problem that the invention seeks to solve]

An object of the present invention is to provide a bidirectional drawing type horizontal continuous casting method that solves the problems of the prior art described above and can prevent the occurrence of breakouts and deterioration of the surface quality of slabs due to the burning of solidified shells into molds. It is in.

[Means and operations for solving the problems] The gist of the present invention is as follows.

That is, in a bidirectional drawing type horizontal continuous casting method in which molten steel is injected from a container such as a tundish into a horizontally arranged mold through a feed nozzle, and solidified slabs are pulled out from both ends of the mold by pinch rolls in opposite directions,
This is a bidirectional pultrusion type horizontal continuous casting method characterized in that a lubricant is injected between the mold and the solidified slab on both sides of the mold except for a 50 to 400 m range at the center of the mold.

The details of the present invention will be explained by referring to Examples. FIG. 1 is a front view showing the entire horizontal continuous casting machine according to an embodiment of the present invention, FIG. 2 is an enlarged sectional view of part A in FIG. 1, and FIGS. 3 and 4 are FIG. 6 is an enlarged front sectional view and an enlarged side sectional view of the mouth portion, respectively. As shown in the figure (50 mm in the central part 6A of the mold 6)
A lubricant 28 is blown between the mold 6 and the solidified shell 16 through a groove 24 provided in the drawing direction on the inner surface of both side parts 6B excluding the range of ~400 m+i and a blowing pipe 26. Forms a film.

As the lubricant 28, an inert gas such as Ar gas or N2 gas, a lubricating oil such as rapeseed oil, graphite powder, or a mixture thereof is used.

The range of the non-lubricated area of the mold center part 6A is 50 to 40.
The reason for limiting the range to 0 mm is that molten steel exists immediately after injection in the range of less than 50 mm, and breakage of the solidified shell 16 can occur even in this range, but if the solidified shell 16 breaks at the 0 mm part, This is because the lubricant 28 may get mixed into the solidified shell 16 and deteriorate the quality of the slab 12. On the other hand, 400
This is because if the non-lubricated region is set to exceed mm, seizure will occur in this non-lubricated region and the effect of the present invention will be diminished. In general, in the case of low-speed casting, the breaking point is stable at the center, so the 50 mm non-lubricated area range of 50 to 400 mm.
In the case of high-speed casting, the breaking point becomes unstable, so it should be a wide range close to 400 mm.

In the present invention, as described above, a film of lubricant 28 is formed between the mold 6 and the solidified shell 16, which reduces friction, prevents seizure, and prevents breakout, and produces the slab 12 with good surface quality. You can get it.

〔Effect of the invention〕

The present invention injects lubricant between the mold and the solidified shell on both sides of the mold, excluding the 50-400mm area at the center of the mold, forming a film of lubricant between the two to reduce friction and prevent seizure. By doing so, it has been possible to prevent the occurrence of breakout 1- and to improve the surface quality of the slab.

[Brief explanation of the drawing]

Fig. 1 is a front view showing the entire horizontal continuous casting machine according to an embodiment of the present invention, Fig. 2 is an enlarged cross-sectional view of part A in Fig. 1, and Figs. 3 and 4 are respectively the four parts of Fig. 1. An enlarged front sectional view and an enlarged side sectional view, Fig. 5 (A) and (B) show a bidirectional drawing type horizontal continuous casting machine. A) is a front sectional view, (B) is a side sectional view, and Fig. 6 7(A), (B), (C) are cross-sectional views showing the formation of a solidified shell in the mold during normal horizontal continuous casting.
), (D) are schematic partial cross-sectional views showing the occurrence of breakout caused by burn-in, (A) is normal, (B
) is the case of the first breakage due to seizure, (C) is the case of the second breakage, and (D) is the case of the breakout due to overlap of seizures. 2. Molten steel 4. Tundish 6. Mold 6A..Mold center section 6B..Mold both sides 8..Feed nozzle 12..Slab 16..Solidified shell 18..Setting part 24.Groove 26.-Blowing Pipe 28...Lubricant

Claims (1)

[Claims] (1) Bidirectional drawing type horizontal continuous casting in which molten steel is injected from a container such as a tundish into a horizontally arranged mold through a feed nozzle, and the solidified slab is pulled out from both ends of the mold in opposite directions using pinch rolls. A bi-directional drawing type horizontal continuous casting method, characterized in that a lubricant is injected between the mold and the solidified slab on both sides of the mold except for a 50-400 mm range at the center of the mold.