JPH01150433A - Mold equipment for continuous casting of hollow slabs - Google Patents

Abstract

PURPOSE:To improve the quality of a hollow cast billet by forming a heat insulating refractory wall at upper ends of the outer face and the inner face of a mold, respectively and arranging them so as to be possible to integratedly oscillate in the vertical direction. CONSTITUTION:The upper ends of the outer face mold 2 and the inner face mold 3 are arranged at lower part of molten metal surface 4a, and further the heat insulating refractory walls 6, 9 are integratedly arranged at the upper ends of both molds 2, 3 through brake rings 5, 11. Successively, the molds 2, 3 are arranged so as to be possible to integratedly oscillate in the vertical direction together with the refractory walls 6, 9 and the mold rings 5, 11. When the molten metal 4 flows into the gap between the mold 2, 3, as the upper end of each mold is lower than the molten metal surface 4a, the flowing is held to good. As each mold is vertically oscillated, burnt-sticking of the shells 1a, 1b is prevented. By this method, the quality of the hollow cast billet 1 is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a molding device for continuous casting of hollow slabs.

[Conventional technology]

In order to manufacture metal pipes by omitting the drilling process, attempts have been made to cast hollow slabs with an annular cross section as the raw material by continuous casting.

This casting method uses a molding device in which an inner mold (core mold) for forming the inner surface and solidified shell of the hollow slab is placed inside an outer mold for forming the outer solidified shell of the hollow slab.

Molten metal is continuously injected into the space between the outer mold and the inner mold, where it is cooled by cooling water through the mold wall to form the outer solidified shell and the inner solidified shell of the hollow slab. Then, the solidified or unsolidified slab is continuously pulled out from the lower ends of the outer mold and the inner mold, and thus the hollow slab is continuously cast.

[Problem that the invention seeks to solve]

By the way, in the above-mentioned molding apparatus, thin wall (for example, wall W
-50 rMn or less), the molten metal must be injected into the narrow space between the outer mold and the inner mold, making injection difficult and causing fluctuations in the level of the injected molten metal. It is unavoidable that this will occur to a large extent. For this reason, solidified shells could not be normally formed on the wall surfaces of the outer mold and the inner mold, making it difficult to cast thin hollow slabs of good quality.

On the other hand, a molding device for continuous casting of thin hollow slabs has also been proposed, in which the outer mold side is the real top. In this method, the upper end of the outer mold is located below the level of the molten metal, and an insulating refractory wall is provided at the upper end, extending above the level of the molten metal.

However, even with this molding device, the inner mold remains in its original position where it contacts the molten metal surface, so the formation of a solidified shell on the wall surface of the inner mold is affected by the melt surface fluctuation, so the hollow slab is The problem still arises that the quality of the inner side is not good.

Therefore, an object of the present invention is to provide a molding device for continuous casting of hollow slabs, which can cast hollow slabs with good quality on both the outer and inner surfaces even if the hollow slabs are thin. That is.

[Means for Solving the Problems] The molding device of the present invention provides an upper end of an outer mold for forming an outer solidified shell of a hollow slab, and an inner solidified shell of the hollow slab disposed inside the outer mold. The upper end of the forming inner mold is located below the level of the molten metal, and the upper end of the outer mold and the upper end of the inner mold are respectively provided with heat insulating fireproofing that extends above the level of the molten metal. A material wall is provided via a break ring, and the outer mold, the break ring thereon and the refractory wall, and the inner mold, the break ring thereon and the refractory wall are each integrally formed. It is characterized by being able to vibrate up and down.

The molding apparatus of the present invention will be described in detail below.

FIG. 1 is a vertical sectional view showing one embodiment of the molding apparatus of the present invention. In FIG. 1, 1 is a thin hollow slab with an annular cross section, and 2 is an outer solidified shell 1a of the hollow slab 1.
3 is an inner mold disposed inside the outer mold 2 and also forms the inner solidified shell 1b.

The upper end of the outer mold 2 is located below the level 4a of the molten metal 4, and a heat insulating refractory wall 6 is provided on the tapered surface of the upper end via a break ring 5. The break ring 5 is for securing the starting point of the solidification of the shell 1a on the wall surface of the outer mold and for making the solidification start position constant. The outer mold 2, the break ring 5, and the refractory wall 6 are connected to the lower flange 6a of the refractory wall 6 by bolts 7 to the upper flange 2a of the outer mold 2.
They are joined together by fixing them together.

Note that it is also possible to integrally connect the refractory wall 6 by applying a pressing force from above.

In order to prevent the shell 1a from seizing on the wall surface of the outer mold 2, a vibration means (not shown) is provided, for example, on the lower surface of the water surface 8 of the outer mold 2. The outer mold 2 is vibrated up and down together with the break ring 5 and the refractory wall 6 by a vibrating means. The refractory wall 6 extends above the level 4a of the molten metal 4. Refractory wall 6
and the refractory wall 9 on the inner mold 3.
In order to make it easier to pour the molten metal 4 from scratch, it is preferable that the inner surface of the refractory wall 6 be sloped upward as shown in the figure.

Like the upper end of the outer mold 2, the upper end of the inner mold 3 is located below the level 4a of the molten metal 4, but the molten metal 4 is placed in the space between the outer mold 2 and the inner mold 3. To make it easier to flow into the outer surface\mold 2
It is located above the top of the . This is because when the hollow slab 1 to be cast is thin, the space between the outer mold 2 and the inner mold 3 is narrow, making it difficult for the molten metal 4 to flow into it. Therefore, when casting a thick hollow slab, the upper ends of these molds 2.3 may be located on the same horizontal plane.

Similarly, the above-mentioned heat-insulating refractory wall 9 is provided at the upper end of the inner mold 3 via a break ring 11 on its tapered surface. The refractory wall 9 is fitted into a holding part 12 integral with the inner mold 3, and the holding part 12 is fitted into a holding arm 13 above it. A cooling water supply pipe 14 for the inner mold 3 is inserted into the space/gap passing through the central axes of the holding arm 13, the holding part 12, and the inner mold 3 from above. The holding arm 13 presses the refractory wall 9 downwardly through the pressing ring 15, whereby the inner mold 3, the break ring 1 and the refractory wall 9 are integrally connected.

In order to prevent the shell 1b from seizing on the wall surface of the inner mold 3, a vibration means (not shown) is provided above the holding arm 13, for example. The inner mold 3 is vibrated up and down together with the break ring 11 and the refractory wall 9 by the vibrating means.

The vibration may be synchronized with the vibration of the outer mold 3 or may be made independent.

In the molding device of the invention, the molten metal 4 is continuously injected from the injection nozzle 10 between the refractory wall 6.9 and flows between the outer mold 2 and the inner mold 3 through its lower part. At this time, since the upper end of the outer mold 2 and the upper end of the inner mold 3 are shifted in the vertical direction, even if the space between these molds 2 and 3 is narrow, the fluid can flow in well. The molten metal that has flowed between the outer mold 2 and the inner mold 3 forms shells la and lb on their respective walls,
Solidified or unsolidified slabs are continuously drawn out from the lower ends of these molds 2.3. As a result, thin hollow slabs 1 having an annular cross section are continuously cast.

At this time, even if the molten metal level 4a of the molten metal 4 fluctuates, since the molten metal level 4a is at the position of the refractory wall 6.9 above the outer mold 2 and the inner mold 3, the outer mold 2 and the inner mold 3 The formation of shells la, lb on the walls of is unaffected; shell la.

1b is formed normally. Also, since both the outer mold 2 and the inner mold 3 are vibrated, the shells la and l
Therefore, a thin hollow cast piece 1 with an annular cross-section that is good on both the outer surface and the inner surface can be obtained.

In the embodiments described above, the case where a thin hollow slab with an annular cross section is cast has been described, but the present invention is not limited to this, and even when casting a thick hollow slab, suitable methods such as a rectangular annular cross section can be used. It is equally applicable to casting hollow slabs with a cross-sectional shape of .

[Effects of the Invention] According to the molding apparatus of the present invention, even if the hollow slab is thin, it is possible to continuously cast a hollow slab with good quality on both the outer surface and the inner surface. Incidentally, a thin hollow steel slab with an annular cross section having an outer diameter of 170 ma+ and an inner diameter of 100 mm was cast at a casting speed of 4 m/min using a molding apparatus similar to that shown in FIG.

[Brief explanation of the drawing]

FIG. 1 is a vertical sectional view showing an embodiment of the molding apparatus of the present invention, in which 1... hollow slab;
1a... External solidified shell, 1b... Inner solidified shell, 2... External mold, 3... Inner mold, 4... Molten metal, 4a... Molten metal surface, 5.11... Break ring, 6.9... Refractory wall, 8... Water surface, 10...
Injection nozzle, 14... cooling water supply pipe. Applicant Nippon Kokan Co., Ltd.

Claims (1)

[Claims] The upper end of the outer mold for forming the outer solidified shell of the hollow slab,
The upper end of the inner mold for forming the inner solidified shell of the hollow slab, which is disposed inside the outer mold, is positioned below the level of the molten metal, and the upper end of the outer mold and the inner mold A heat insulating refractory wall extending above the level of the molten metal is provided at the upper end via a break ring, and the outer mold, the break ring and the refractory wall thereon, and the 1. A molding device for continuous casting of hollow slabs, characterized in that an inner mold, the break ring thereon, and the refractory wall can each vibrate up and down integrally.