JPH071088A - Belt-type continuous casting machine belt - Google Patents

Abstract

(57) [Abstract] [Purpose] The purpose is to increase the cooling capacity by providing dimples on the belt of a twin-belt continuous casting machine or a single-belt continuous casting machine to achieve high-speed casting and high quality. And A twin-belt continuous casting machine consisting of a pair of belt molds and a pair of short-side molds that run endlessly with at least two drive pulleys, or a belt that runs endlessly with at least one drive pulley In a belt used in a single-belt continuous casting machine consisting of a mold, a rear weir provided if necessary, and / or a pair of side weirs, in order to improve heat transfer of the belt, a cooling water contact surface is provided. A concave dimple is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvement of belt cooling capacity of a twin belt type continuous casting machine or a single belt type continuous casting machine for cooling and solidifying molten metal through a belt.

[0002]

2. Description of the Related Art A twin-belt type continuous casting method or a single-belt type continuous casting method is one of the processes for producing thin metal slabs. For example, in the twin-belt continuous casting method, as shown in FIG. 4, the molten metal of the tundish 7 is passed through the flow control valve 9 and the nozzle 10 into a belt mold formed by the belts 3a and 3b supported by the pulleys 12a and 12b. Injected.

This belt mold forms a space in which a wide thin slab can be cast by partitioning the endless drive belt and both sides on the short side. The injected molten steel is jet water flow zones 14a, 1
4b and then completely cooled as a slab in the cooling pad zones 15a, 15b. The cooling pad band is composed of a large number of cooling water pipe rows 16a and 16b. In addition,
The jet water flow zones 14a and 14b may be omitted.

Conventionally, a substantially flat steel strip is used for the belt on both the molten metal contact side and the cooling water side. Japanese Unexamined Patent Publication No. 1-138041 discloses that if the surface has fine irregularities, the shell thickness can be made uniform. The same applies to a single-belt continuous casting machine, and JP-A-63-278648 discloses that cold shut is prevented by providing irregularities on the surface of the molten metal side belt. Hitherto, a high heat removal type belt has been required to meet the requirements for longer life of the belt and slab quality, but many constraints have not been realized.

[0005]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention improves the cooling ability of the belt of a twin belt type continuous casting machine or a single belt type continuous casting machine and requires a high heat flux. It can be used for slab production and high-speed casting,
Moreover, it is intended to reduce the contact unevenness between the slab and the belt by achieving a long life and reducing the thermal deformation of the belt during casting. That is, an object of the present invention is to provide a high-performance belt which improves the heat removal ability of the belt, achieves high heat transfer, maintains the quality of the slab at a high level, and improves the productivity.

[0006]

SUMMARY OF THE INVENTION The present invention is a twin-belt continuous casting machine comprising a pair of belt molds and a pair of short side molds that run endlessly with at least two drive pulleys, or at least one drive pulley. In a belt used in a single-belt continuous casting machine consisting of one belt mold that runs endlessly by means of, and a rear weir and / or a pair of side weirs provided as necessary, the heat transfer ability of the belt is improved. For this purpose, concave dimples are formed on the cooling water contact surface. This concave dimple is formed by a processing method such as shot blasting, photoetching, laser, chiseling or the like. Ideally, the concave dimples thus obtained have a constant center-to-center distance and are evenly distributed on the belt surface, but the situation varies depending on the processing method.

[0007]

In general, the surface of the belt on the side that comes into contact with the molten metal is surface-treated or coated, and measures are taken to protect it. From the viewpoint of heat removal ability, these act in the direction of decreasing the heat conductivity, and studies have been made to slow the cooling rate.

On the other hand, high-speed casting as a production facility has been studied, and in order to achieve this, it is necessary to increase the heat removal amount and realize a high heat flux in the cooling zone. Further, depending on the quality of the slab, high heat transfer may be required, and high heat flux in the cooling zone is required. The belt cooling water side dimples in the present invention are aimed at the fin effect at the time of cooling, peeling the heat transfer boundary layer to increase the heat transfer coefficient, reduce the load on the cooling zone of the slab, and increase the equipment cost. The life of the belt and the flatness of the belt during operation are improved.

[0009]

EXAMPLES The present invention will be described in more detail with reference to the following examples with reference to the drawings. FIG. 1 shows the condition of the surface of the belt on the cooling water side. The dimples 2 are provided at regular intervals in the longitudinal direction and the width direction of the belt. FIG. 2 shows a cross section of the belt. The dimple 4 has a hemispherical shape and has a uniform recess formed on the surface of the belt. The molten steel contact surface 6, which is the other surface, is covered with a protective coating layer 5.

The protective coating layer 5 is formed of various ceramics such as boron nitride, alumina, and carbide with a thickness of 20 to 150 μm. The dimple 2 in this embodiment has a uniform concave portion 4.
The diameter on the surface is 0.5 to 2.0 mm, which corresponds to the maximum diameter of the concave circle 2.

That is, the depth is 0.25 to 1.0 mm, which is the maximum depth of the recess 4. The distance between the centers of the recesses is 1.0 to 4.0 mm. By providing this dimple, compared with the conventional flat surface, the energy generated by the bubbles generated on the cooling surface is reduced and the bubbles are easily separated, the belt cooling boundary layer is easily separated, and the heat transfer is improved. . In addition, the contact area between the cooling water and the belt increases, and the fin effect has the effect of increasing the amount of heat removed.

Furthermore, by changing the size of the dimples, the heat removal amount in the belt mold can be controlled, and a large heat removal amount is required with the same equipment. It can be used as a large capacity casting machine.

In the present embodiment, comparing the heat fluxes by the continuous casting solidification calculation model of steel, as shown in FIG. 3, it is 3 × 10 ⁶ Kcal / m ² · hr for a normal flat surface belt, but dimples For belts with 3.6 × 10 ⁶ Kcal
/ M ² · hr and it was found that the heat flux increased by about 20%. When this is evaluated by slab quality, in the case of steel, it corresponds to an increase in the thickness of the solidified shell by 1 to 2 mm,
A slab of stable quality can be obtained as compared with a conventional slab.

As the processing method for providing the dimples on the belt in the present invention, there are available ordinary mechanical processing such as shot blast, engraving method with chisel, laser processing method by photoetching and the like.

Although the twin-belt continuous casting method has been described above, the present invention is also applicable to other continuous casting methods such as the above-mentioned single-belt continuous casting method in which molten metal is solidified on the belt surface to obtain a slab. Of course, is applied.

[0016]

According to the present invention, by adopting the above-mentioned constitution, it is possible to increase the belt heat removal amount of the twin-belt type continuous casting machine or the single-belt type continuous casting machine, and to realize high-speed casting and large casting of continuous casting. This contributes to higher capacity and higher quality of cast slab.

[Brief description of drawings]

FIG. 1 is a schematic plan view showing a cooling surface dimple according to the present invention.

FIG. 2 is a schematic sectional view of the belt of the present invention.

FIG. 3 shows the relationship between the heat flux and the casting time as the cooling capacity in the continuous casting equipment for steel of the present invention and the conventional belt.

FIG. 4 is a schematic configuration diagram of a twin belt type continuous casting method.

[Explanation of symbols]

 1 ... Belt cooling water contact surface 2 ... Dimple 3 ... Belt 4 ... Dimple recess 5 ... Molten steel contact surface 6 ... Protective coating layer 7 ... Tundish 8 ... Molten metal 9 ... Flow control valve 10 ... Nozzle 11 ... Cast slab 3a, 3b ... Belts 12a, 12b ... Upper pulleys 12c, 12d ... Intermediate pulleys 13a, 13b ... Driving pulleys 14a, 14b ... Jet cooling 15a, 15b ... Pad cooling 16a, 16b ... Cooling water pipes

Claims (1)

[Claims] 1. A twin-belt continuous casting machine consisting of a pair of belt molds and a pair of short-side molds that run endlessly with at least two drive pulleys, or one endless run with at least one drive pulley. In a belt used in a single belt type continuous casting machine comprising a belt mold and a rear weir and / or a pair of side weirs provided as necessary, concave dimples were formed on the cooling water contact surface of the belt. A belt for a belt-type continuous casting machine, which is characterized in that