JPS6236781B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an open continuous casting mold that applies high frequency vibrations.

The present inventors have previously developed a mold with both ends open for continuous casting of molten metal, in which the part of the mold in contact with the metal to be cast is divided into a plurality of parts, and each part is vibrated. We have proposed a mold for continuous casting of metal, which is formed by connecting a vibration generator that applies vibrations of 5 to 50 KHz to any of the plurality of molds that are connected by means of isolation and in contact with the metal to be cast. (Patent Application No. 53-19455) This proposal is a mold that can reduce the oscillation marks on slabs, reduce surface flaws, and can be applied to a variety of mold shapes, as well as reduce the amount of incident energy. It provides: That is, the mold moving parts to which high-frequency vibrations are applied are distributed at several locations, for example, in the height direction and the width direction, so that the frictional force between the mold moving parts and the slab is reduced on average. It is characterized by the fact that it can be freely selected, such as applying vibration to the area where the frictional force is greatest, or applying vibration intensively to the area where the frictional force is greatest.

The present invention is a further improvement of the above proposal, and in the continuous casting mold that applies high frequency vibration of 5 to 50 KHz, the mold corner portion that constitutes the joint between the wide mold surface and the narrow mold surface is shaped into an arc. A high-frequency vibrator for imparting high-frequency vibration to the corner portion of the mold is disposed.

The corners of continuous casting molds for rectangular slabs are usually rectangular at nearly 90 degrees or have small arc shapes, whereas for circular slabs, the size of the arc can be as large as several tens of millimeters. It may extend. If the corner shape is square, at the corner part of the slab,
Cooling is rapid and temperature unevenness occurs compared to other surfaces, which often causes surface cracks. On the other hand, if the corner part is arcuate, the problem of temperature unevenness is alleviated, but irregular poor contact with the mold, that is, uneven cooling often occurs in the arc locality. I found out.

The present inventors added corner radii to the corner portions of square molds in order to reduce the temperature drop at the corner portions, and also conducted research to solve the uneven cooling caused by uneven contact within the mold due to the arcs of the corner portions. As a result, we found the following.

When a 1/4 arc curved surface is attached to the corner of a square mold, in many cases there is a part on the surface in the longitudinal direction of the center of the arc that makes poor contact with the mold. This phenomenon will be explained with reference to FIG. Figure 1 is a plan view showing the contact situation between the mold and the slab, and there is a thin film of continuous casting powder for lubrication in the gap between the mold and the slab. It may be thicker. As a result, cooling of the corner portions of the slab deteriorates. However, when high-frequency vibration is applied to the corners of the mold, the continuous casting powder for lubrication is pushed toward the surface of the slab in the direction indicated by the mark, and the thickness of the continuous casting powder for lubrication at the corners becomes thinner, improving uneven cooling. Ru.

In addition, in the continuous metal casting mold of the present invention, the frequency of vibration applied to the moving parts of the mold is 5-
The reason for limiting the range to 50KHz is as follows.

In the low frequency range of less than 5KHz, audible sounds are generated and it cannot be used in the work environment, and 50K
In a frequency range exceeding Hz, it is not possible to reduce the friction between the mold and the metal to be cast, which acts as mechanical vibration.

That is, according to the present invention, it is possible to increase the radius of curvature of the corner portion of the mold, prevent breakouts and corner cracks, and ensure uniform flow of continuous casting powder into the mold. The effect is extremely large.

The invention will be explained in detail below with reference to the drawings.

The continuous casting mold of the present invention has mold wide surfaces 1 and 1'.
and mold narrow faces 2, 2', each mold comprising cooling water boxes 3, 6 and copper plates 4, 5. A corner copper plate 9, 9' having a circular arc shape or a curved surface close to an arc shape is provided at the joint between the mold copper plate 4 and the mold copper plate 5. High frequency vibration connecting plates 8 and 8' are connected to the corner copper plates 9 and 9' in a flange shape, respectively, and a high frequency vibrator 1 of 5-50KHz is connected via horns 7 and 7'.
0,10' is provided. the corner copper plate 9;
The radius of curvature of 9' (in the case of a 1/4 arc) is preferably in the range of 10 to 60 mmR. This means that if the radius is less than 10 mm, there is no effect of making the corner part curved, and if the radius is more than 60 mm, it is insufficient to improve the delay in the development of the solidified shell at the corner part due to high frequency vibration of 5-50 KHz. by.

However, with the continuous casting mold of the present invention,
A 1600mm wide, 200mm thick, 40Kg class plate material was cast.
Casting speed 0.7-1.1m/min, mold oscillation
90 times/min, amplitude ±5mm, high frequency vibration 18KHz, power
4KW was installed at each of the four corners. The radius of the corner part was 35mm. As a result, the breakout occurrence rate due to corners was reduced to 3 out of 212 charges, and the corner slab maintenance rate was reduced to 17% from 29% in the known continuous casting method using a normal mold.

[Brief explanation of the drawing]

Figure 1 is a plan view showing the contact situation between the mold and slab;
FIG. 2 is a schematic perspective view of the mold of the present invention, and FIG. 3 is a perspective view of the main parts of the present invention. 1, 1': mold wide side, 2, 2': mold narrow side, 3,
3': wide-sided cooling water box, 4: wide-sided copper plate, 6, 6': narrow-sided cooling water box, 5: narrow-sided copper plate, 9: corner copper plate, 10: high-frequency vibrator.

Claims (1)

[Claims] 1. In an open continuous casting mold that applies high-frequency vibrations of 5-50 KHz, mold corner portions that constitute the joint between the wide mold surface and the narrow mold surface are formed in an arc shape, and high-frequency vibrations are applied to the mold corner portions. A mold for continuous casting of metal.