JPH0448Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an immersion tube for a vacuum degassing device that is structurally strong and has excellent durability.

(Prior Art) The immersion pipe attached to the lower part of a vacuum degassing device has a short service life due to harsh operating conditions in which the outer periphery is immersed in molten steel and the inner periphery is immersed in molten steel.

The structure of a conventional immersion pipe is generally a brick support as shown in Japanese Patent Application Laid-Open No. 110630/1983. As shown in Figs. 2 and 3, the structure of this immersion tube is as follows: As shown in Figs. A refractory layer 4 is provided, the outer periphery of the core metal 2 is made up of a castable refractory layer 3b, and a supporting metal fitting 5 is provided on the inner surface of the core metal 2 in order to support the refractory layer 4.
is provided protrudingly to support the lowest refractory brick 4a.

(Problems to be Solved by the Invention) In the conventional immersion pipe described above, the lowermost refractory brick 4a is supported by a support fitting 5 in order to support the refractory brick layer 4. Therefore, during use, the expansion of the refractory brick layer 4 is greater than the expansion of the core bar 2, resulting in the problem that restraint stress is concentrated on the portion where the support fitting 5 and the refractory brick layer 4 are in contact, and cracks 11 are likely to occur. The crack 11
As shown in FIGS. 4a and 4b, this condition occurs mainly in the support fitting 5 portion of the lowest refractory brick 4a. When the crack develops, molten steel enters and melts down the core metal 2, causing the lowermost refractory brick 4a to fall off, resulting in damage to the entire immersion pipe.

As shown in Fig. 5, the service life of the immersion pipe is generally affected by peeling and melting of the lower end of the castable refractory layer 3b. Therefore, it is better to construct the outer castable refractory layer 3b thicker at the lower end. Due to the inner diameter of the ladle when dipping, it cannot be applied too thickly. The present invention aims to solve these drawbacks of the conventional technology.

(Means for Solving Problems) The present invention provides a layer of refractory bricks stacked in a cylindrical manner with a castable refractory layer interposed on the inner peripheral surface of a cylindrical cored metal having a flange at the upper end, and This immersion tube for a vacuum degassing device is a immersion tube whose outer peripheral surface is made of a castable refractory layer, in which a sloped portion is formed toward the inner periphery at the lower end of the metal core.

(Function) As a result of various studies in order to disperse the concentration of thermal stress in the refractory brick layer, the inventors of the present invention made the lower end of the core metal completely sloped toward the inner periphery, and the outer periphery of the lowermost brick layer was It is intended to be fully supported.
Furthermore, a castable refractory is interposed between the inclined surface of the core metal and the lowest refractory brick to alleviate stress.

In this way, the synergistic effect of the support by the entire outer periphery of the lowermost brick and the interposition of the castable refractories effectively eliminates the conventional problem of preventing cracks in the supported portions due to restraint stress or thermal stress.

The present invention will be explained below based on the drawings.
As shown in the figure, a cylindrical core bar 2 has a flange 1 at its upper end and a lower end inclined toward the inner periphery.
A brick 4a obtained by cutting the lowest refractory brick 4a parallel to the core metal 2 through a castable layer 3a of about 30 mm.
A stacked refractory brick layer 4 containing The outer periphery of the core metal 2 is covered with a castable refractory layer 3b having a thickness of, for example, about 60 to 200 mm. Although not shown, it is preferable to install a large number of studs on the outer peripheral surface of the core bar 2 to hold the castable refractory layer 3b. An inclined part 6 is formed at the lower end of the core bar 2 toward the inner circumferential side, and its angle is 10 to 40 degrees, preferably 15 to 30 degrees, and the length of the inclined surface is 1/3 of the length of the core bar 2. preferable. The back surface of the lowest refractory brick 4a in the refractory brick layer 4 needs to be processed into the same shape as the core bar 2. It is the refractory brick layer 4 that slopes only the lowest brick 4a.
In addition to effectively supporting the refractory brick layer 4, the shape of the refractory brick layer 4 that requires processing can be reduced. Therefore, the variety of shapes and dimensions of the refractory brick layer 4 is reduced, which is advantageous in manufacturing the bricks and the refractory brick layer 4. The joint allowance of the refractory brick layer 4 and the joint between the refractory brick layer 4 and the castable 3b are preferably designed to absorb expansion of the refractory brick layer 4 as much as possible. The thickness of the core metal 2 is required to be about 10 to 20 mm in order to receive the expansion of the refractory brick layer 4 in the vertical direction and the inner circumferential direction.

If the above-mentioned inclination angle is smaller than 10°, the lowermost refractory brick will easily fall off at the end of its use. Also
This is because if the angle is larger than 40°, the restraining force by the core metal becomes large, making it impossible to prevent cracks. The present invention supports the refractory brick layer 4 by forming an inclined part 6 toward the inner circumference at the lower end of the core metal 2, and supports the core metal 2 through the castable refractories 3b to receive stress during use. This is to avoid cracking due to stress concentration at one point. The lower end of the core 2 of a dipping tube during use tends to open in a floppy shape due to the expansion of the refractory, but in the present invention, the core 2 is squeezed and the thickness of the core 2 is taken into consideration to open the bottom end in a floppy shape. It also prevents this.

Furthermore, by squeezing the core metal 2, the thickness of the lower end of the outer castable refractory becomes thicker, thereby dealing with peeling and wear of the castable.

(Effects of the invention) As a result of using this invention in the immersion pipe of an RH type vacuum degassing equipment, no cracks were observed in the refractory brick layer even after 80 charges, and the service life was 50 years longer than that of the conventional method.
% improvement, and no deformation or melting of the core metal was observed even in the results of a disassembly inspection after use.

[Brief explanation of drawings]

Figure 1 is a front sectional view of the structure of the immersion pipe according to the present invention, Figures 2 and 3 are front sectional views of the structure of the immersion pipe of the conventional method, and Figure 4 is the structure due to the support metal fittings of the lowermost refractory brick of the conventional method. Fig. 5 is a diagram showing the state of crack occurrence, and Fig. 5 is a diagram of the state of melting and damage of the immersion pipe. 1...Flange, 2...Cylindrical core metal, 3a...
Castable refractory layer, 3b...Outer castable refractory layer, 4...Refractory brick layer, 4a...Lowermost refractory brick, 5...Supporting metal fittings, 6...Slope portion, 11
...Crack, 12...Erosion part.

Claims (1)

[Scope of utility model registration request] A refractory brick layer 4 stacked in a cylindrical manner via a castable refractory layer 3a is provided on the inner circumferential surface of a cylindrical cored metal 2 having a flange 1 at the upper end, and the outer circumferential surface of the cored metal 2 is covered with a castable refractory. A immersion tube for a vacuum degassing device, comprising a immersion tube composed of a layer 3b, in which a sloped portion 6 is formed toward the inner circumference at the lower end of one-third or less of the length of the core bar 2.