JPH03114632A - Short side plate of continuous thin slab casting machine - Google Patents

Abstract

PURPOSE:To form short side plate restraining the development of penetration of molten metal into joint part during casting by setting refractory with fibers specified in coefficient of linear expansion and high temp. strength embedded between metal frame casing parts of the short side plate with the intermediate part squeezed into the shape of top-widening and bottom-narrowing. CONSTITUTION:A cast strip continuous casting machine is constituted of long side faces with circulating bodies composed of one pair of metal belts 1, 2 and short side faces with one pair of the short side plates 4, 5 to form casting space. This short side plate 4, 5 is constituted of a metal frame 8 and the refractory 10, and the metal frame 8 has the casting parts 9 squeezed as arc-like into the shape of top-widening and bottom-narrowing to support the refractory 10 between these casing parts 9. Then, in the refractory 10, the fibers 11 (about 0.5mmphi wire diameter, abut 20-30mm length) having smaller coefficient of linear expansion (<= about 1X10<-6>/ deg.C) and more excellent high temp. strength (about 10kg/mm<2>) than those of the refractory 10, are uniformly embedded in longitudinal direction. By this method, the short side plates 4, 5 having a little expansion difference between the longitudinal direction and width direction in the refractory 10 during casting, is obtd. and development of breakout is prevented from occurring.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a short side plate that forms a casting space together with a pair of circulating bodies in a continuous thin slab casting machine that directly produces thin slabs from molten metal. .

(Prior Art) Recently, various types of continuous casting machines have been proposed that continuously produce thin slabs such as sheet bars directly from molten metal (the following will be explained using the example of "molten steel"). . For example, there are Heruto casters, block casters, twin roll casters, etc., and the Heruto caster is shown in FIG. 4 as a typical example.

The illustrated synchronous helt caster is of the squeezing type and has a plurality of guide rolls 3a, 3b, 3c, respectively, while maintaining a gap for holding the cast material such as molten steel or solidified shell over a predetermined distance. Metal belts 1 and 2 support a pair of long side surfaces arranged oppositely and pivoted through the metal belts, and support short side surfaces that are in close contact near the respective side edges between the two metal belts. The upper and lower concave short side plates 4 and 5 confine the casting space on four sides.

When molten steel is supplied into the casting space from the immersion nozzle 6, the metal healds 1 and 2 are cooled by cooling pads 7a and 7b.
The molten steel that comes into contact with 2 is drawn downward while forming a pseudo-solid shell.

In order to delay solidification on the short sides, it is advantageous to form the inner surfaces of the short side plates in contact with the molten steel with a refractory material. This disclosure discloses a short-side side plate in which a refractory is supported by a frame part on a metal frame (cooled copper plate) having a frame part.

(Problems to be Solved by the Invention) When using this short side plate, it is necessary that: ■ There is little erosion loss on the contact surface of the refractory with the molten steel, and ■ The refractory is connected to the metal frame to the extent that the molten steel does not solidify on the refractory surface. It is important that it is insulated, and that molten steel is not inserted into the boundary between the refractory and the frame, so-called joints.

Therefore, materials with high high temperature strength such as Sialon and 5iJn are used for the refractory to satisfy the above condition (2).On the other hand, these materials have higher thermal conductivity than fused silica etc., so the gap between the refractory and the metal frame is Insulation material is applied to satisfy the above item (■).

Furthermore, regarding (■) above, before installing the refractory inside the metal frame, the side edges of the refractory are ground to create a border that leaves a width that takes into account the expansion of the refractory during casting. I am coping by doing this.

The width of this border 1-1 is usually narrow, 0.1 to 0.3 mm, and
..., the shape of the refractory on the short side plate used in the caster is long in the vertical direction, and the amount of expansion in the vertical direction during casting is larger than in the horizontal direction, so the refractory is supported by the frame of the metal frame. When the refractory material becomes too tight, the refractory material lifts up from the metal frame, and as a result, the gap between the refractory material and the metal frame widens, and a joint gap occurs there.

Then, a solidified shell is generated on the short side plate starting from the joint, and when this shell grows until it becomes impossible to drag debris downward by the shell on the long side of the mold, the shell breaks on the short side of the mold and the mold shortens. This leads to a breakout just below the edge.

Therefore, an object of the present invention is to propose a short side plate that has a small difference in the amount of expansion between the longitudinal and lateral directions of a refractory during casting.

(Means for Solving the Problems) The present invention provides a pair of circulating bodies arranged opposite each other that circulate while maintaining a gap for holding molten metal over a certain distance, and both side edges between the circulating bodies. The short side plate of the thin slab continuous casting machine is in contact with the circulating body, and the short side plate of the thin slab continuous casting machine constitutes a casting space with the short side plate whose middle part is narrowed down by a pair of upper wide and lower recesses located at the upper and lower sides. It has a frame part formed on both side edges and a refractory supported between the frame parts, and a fiber having a smaller linear expansion coefficient and excellent high temperature strength compared to the refractory is applied to the refractory along the length of the refractory. This is a short side plate of a continuous thin cast slab casting machine, which is characterized by being buried in the same direction.

(Function) The short-side side plate according to the present invention has fibers that have a smaller coefficient of linear expansion and excellent high-temperature strength than the refractory, which are embedded in the longitudinal direction of the refractory, thereby increasing the expansion of the refractory in the longitudinal direction. This is inhibited by fibers to minimize the difference in the amount of expansion in the vertical and horizontal directions of the refractory.

Therefore, the expansion of the refractory is completely absorbed in the gap between the frame and the refractory, and the refractory does not rise up from the frame.

(Example) FIG. 1 shows a short side plate according to the present invention.

The short-side side plates are formed by supporting a refractory 10 at frame parts 9 provided on both sides of a metal frame 8 whose middle part is narrowed into an arc shape with a concavity at the top and bottom. Further, inside the metal frame 8, there is provided a refrigerant passage through which cooling water and the like circulate.

The refractory 10 is made by embedding fibers 11 which have a smaller coefficient of linear expansion and excellent high-temperature strength than the refractory and are aligned in the longitudinal direction of the refractory.

The fiber 11 has a coefficient of linear expansion of IXl0-6/''C
Below, a material with a high temperature strength of 10 kg/mm'', such as high-strength graphite fiber, is suitable, and this material has a wire diameter of 0.5 mmΦ and a length of 20 to 30 mm.
It is preferable to embed it uniformly in the refractory.

Furthermore, continuous casting using short side plates according to the present invention will be specifically explained.

For the belt caster shown in Fig. 4, graphite (linear expansion coefficient: 0.5X 10
-6/°C) short side plates with embedded fibers were applied. Here, each dimension of the refractory shown in Figure 2 is 1-14
0 mm, h = 750 mm and R = 1500 mm.

With this heald caster, low carbon aluminum killed steel can be cast at a casting speed of 15+n/min to a thickness of 30mm and a width of 20mm.
When casting was carried out to form a slab of 0mm and length 3 x 10'm, the temperature of the refractory during casting was 1300°C, and the expansion length of the refractory in the longitudinal direction (direction A - longitudinal direction in Figure 2) was 0.2 mm, and the expansion length in the lateral direction (direction B in Figure 2) was 0.3 mm, and the refractory did not lift up from the frame of the metal frame.

In addition, for comparison, when a short side plate of the same shape and material but with no fiber embedded in the refractory was subjected to the same casting process, the vertical expansion length of the refractory reached 1 mm, and Objects would lift up and create joint gaps, often leading to breakouts. The breakout incidence rate is shown in FIG.

In addition, the surface of the short side plate] Large pieces are vertically long in the above-mentioned twin-held type continuous casting machine, but are often horizontally long in, for example, a twin-roll type continuous casting machine, and in this case, the fibers are All you have to do is line up and bury them.

(Effects of the Invention) According to the present invention, the amount of expansion during casting of the refractory to be incorporated into the picture frame can be reduced and made almost uniform in the vertical and horizontal directions, so that the refractory does not rise from the picture frame. Therefore, the occurrence of breakouts caused by joints can be prevented.

[Brief explanation of drawings]

The first is an explanatory diagram showing the short side plate according to the present invention, FIG. 2 is a front view of the short side plate, FIG. 3 is a graph showing the incidence of breakout, and FIG. 4 is an explanatory diagram of the belt caster. 1.2...Metal belt 3a+ 3b+ 3c...Guide roll 4.5...
Short side plate 6...Immersion nozzle 7a, 7b...
Cooling pad 8...Metal frame 9...Picture frame part
10... Refractory 11... Fiber

Claims (1)

[Claims] 1. A pair of circulating bodies arranged opposite each other, which circulate while maintaining a gap for holding molten metal over a certain distance, and located on both side edges between the circulating bodies. In the short side plate of a thin slab continuous casting machine, which constitutes a casting space with a short side plate whose middle part has a narrowed shape with a pair of upper and lower recesses, A frame part and a refractory supported between the frame parts are provided, and fibers having a smaller coefficient of linear expansion and superior high-temperature strength than the refractory are embedded in the refractory, aligned in the longitudinal direction of the refractory. A short side plate of a continuous thin cast slab casting machine.