JPH0318039Y2 - - Google Patents

Description

[Detailed explanation of the idea]

[Industrial Application Field] The present invention relates to a sliding nozzle (hereinafter abbreviated as SN) device attached to a molten metal container.
In particular, it relates to the structure of an upper nozzle (also referred to as an insert nozzle or upper nozzle) that blows inert gas into molten steel. [Conventional technology] As an automatic control means for the flow rate of molten steel, the SN method enables long-term molten steel processing such as bubbling, DH, and RH, and is used to improve quality, reduce costs, improve workability, save labor, etc. For example, in the case of tundish casting, it is required to extend the casting time by continuous casting and to strictly control the casting speed. Therefore, in order to prevent nozzle clogging caused by alumina inclusions adhering to the inner hole of the upper nozzle due to alumina precipitation or solidification of molten steel, bubbling with an inert gas such as argon or nitrogen is the most effective method. Various methods have been tried to prevent nozzle blockage, and generally the upper nozzle has a porous brick or a built-in bubbling function such as creating slits inside the brick. It is true. However, conventionally, as shown in FIG. 1, a space 3 is provided between the outer peripheral surface of the porous brick 1 and an iron plate case 2 surrounded by a metal hoop, or a second
As shown in the figure, there is a slit 5 inside the porous brick 1.
After blowing inert gas into the porous brick 1
Inert gas is injected into the molten steel flow in the inner hole through the pores, but since the inert gas supply pipe 4 is located below the upper nozzle, there is less flow from the upper side of the upper nozzle than from the lower side. Inert gas discharge is poor. Therefore, the alumina-based inclusions in the molten steel adhere to the upper side of the inner hole of the upper nozzle, reducing the amount of molten steel flowing out, which has the disadvantage that the specified production cannot be achieved. Also, in Utility Model Publication No. 57-70752, there is a
A gas permeable upper nozzle for a molten metal container having a plurality of blowholes of 0.1 m/m or more and connected to a gas distribution chamber by a through hole is described. As shown in the above, the nozzle is provided around the outer periphery of the side surface of the upper nozzle, and there are problems during actual manufacturing and use as described below. Furthermore, in Japanese Utility Model Application No. 51-30809, a groove 7b is provided on the outer peripheral surface of a nozzle block 7 having an appropriate porosity, and a split-type fire-resistant annular body 8 having a higher porosity than this nozzle block 7 is combined. The annular body 8
It is disclosed that several air grooves 16 are also provided on the outer peripheral surface of the nozzle block to evenly distribute the inert gas, and these nozzle blocks can be used as the upper nozzle. [Problems to be solved by the invention] The problems with the invention described in the above-mentioned Japanese Utility Model Application No. 57-70752 are as follows: (1) The steel plate mantle (iron plate) surrounding the side of the upper nozzle (porous brick 1) The case 2) is usually enclosed by shrink fitting, but in this case, in the gas distribution chamber 8 of the invention, as shown in FIG. As a result, it becomes concave toward the gas distribution chamber 8 side, making it impossible to perform a sufficient shrink fit. In order to prevent this, it is necessary to make the steel plate jacket (steel plate case 2) sufficiently thick, or to make the width (height direction) of the gas distribution chamber 8 as narrow as possible.
As a result, it is not possible to provide a gas distribution chamber 8 above the inner hole of the upper nozzle, or into the entire inner hole, which allows inert gas to be blown into the inner hole. (2) The gas distribution chamber 8 needs to be provided by changing the metal frame structure from the previous one when molding the brick for the upper nozzle, which affects the complexity and difficulty of molding and also affects the economy. (3) Since the gas distribution chamber 8 is provided around the outer circumference of the side surface of the upper nozzle (porous brick 1), if the top of the upper nozzle is damaged and molten steel enters the gas distribution chamber 8, the upper This will cause major damage to the entire nozzle, and there is a high risk of steel leakage. (4) When the purpose is to prevent alumina-based inclusions from adhering to the inner hole of the upper nozzle, inert gas is blown from the gas distribution chamber 8 through the through hole 6 and through the blowhole 7 provided at the top of the upper nozzle. There's no need to go into it. (5) It is difficult to provide through holes 6 with a diameter of about 0.1 to 1 m/m when manufacturing bricks for the upper nozzle. It is necessary to install it almost to the top of the roof, and there is a great danger if the upper part is damaged. (6) When a certain amount of inert gas is supplied from gas supply pipe 4, porous refractory (porous brick 1)
Since the amount of inert gas exiting from the fumarole hole 7 is larger than the amount of inert gas exiting from the inner hole surface of the upper nozzle through the pores of The effect of preventing nozzle clogging cannot be sufficiently achieved. The device described in the above-mentioned Japanese Utility Model Application Publication No. 51-30809 requires the use of two types of breathable refractories with different porosity, and in addition, a large number of air grooves 16 are provided on the outer periphery of the split annular body 8. However, it is extremely complicated in structure and complicated to assemble, and has the same drawbacks as the above-mentioned known technology. [Means for Solving the Problems] In order to solve the problems of the prior art as described above, the present invention has a technical configuration as specified in the claims of the above-mentioned utility model registration, and has an outer circumferential surface of a porous brick, A space is created between the surrounding iron plate case,
In addition, by providing ventilation grooves in the vertical and horizontal directions on the outer periphery of the side surface of the porous brick, it is possible to improve the discharge of inert gas from the upper side of the upper nozzle, and prevent nozzle clogging due to adhesion of alumina inclusions. The present invention provides a porous brick structure that facilitates the manufacture of nozzle bricks. Hereinafter, an embodiment of the present invention will be explained in detail based on FIGS. 4 and 5 a and b, which show an embodiment of the present invention. In order to provide a space 3 in the lower part between the outer circumferential surface of the porous brick 1 and the surrounding iron plate case 2, the porous brick 1 for the upper nozzle is manufactured in a predetermined shape, and is provided with holes in the vertical and horizontal directions on the side outer periphery of the porous brick 1 for the upper nozzle. Ventilation grooves 9 and 10 are provided in each. The number of vertical ventilation grooves 9 depends on the amount of inert gas supplied, the air permeability of the porous brick 1, and the amount of inert gas discharged from the upper nozzle inner hole surface necessary to prevent nozzle clogging due to adhesion of alumina inclusions. The amount of inert gas required to be discharged from the inner hole of the upper nozzle varies depending on the molten metal container such as a ladle or tundish in which the SN device is used, and also depends on the size and inner hole diameter of the upper nozzle. However, in order to make the discharge amount of inert gas as uniform as possible on the inner surface of the upper nozzle, 3 to 6 vertical ventilation grooves 9 should be provided at equal intervals, and horizontal ventilation grooves 9 should be provided at equal intervals. When using the upper nozzle, one or two ventilation grooves 10 may be provided by selecting a position where alumina-based inclusions are most likely to adhere and cause problems, and the vertical ventilation grooves 9 are connected from the three spaces. and stop it at the position of the horizontal ventilation groove 10 so that it does not penetrate to the top of the porous brick 1.
In addition, the shape and size of the ventilation grooves 9 and 10 are from radius 2 to
A semicircular shape of about 10R is fine, but after repeated various experiments, we found that in order to discharge inert gas as evenly as possible from the upper and lower sides of the upper nozzle inner hole surface, horizontal ventilation grooves were found. The size of the horizontal ventilation grooves 10 is preferably about 1 to 2 times the radius of the vertical ventilation grooves 9, although it depends on the position and number of the ventilation grooves 10. Then, such ventilation grooves 9, 10
can be provided at the time of molding the porous brick, but it can also be easily provided by processing after firing, and the shape, size and installation method of the ventilation grooves 9 and 10
There is no regulation whatsoever. After providing the ventilation grooves 9 and 10 in the vertical and horizontal directions on the outer periphery of the side surface of the porous brick 1 in this manner, the iron plate case 2 is attached to the porous brick 1 having the ventilation grooves 9 and 10 by a method such as shrink fitting. surrounding the gas supply pipe 4, and attaching the pipe for the gas supply pipe 4 by a method such as welding, and when using the gas supply pipe 4.
The connection is made by screwing a pre-provided spiral into the end of the pipe. The present invention will be further explained below with reference to Examples. Example 1 A vertical ventilation groove 9 was formed on the outer periphery of the side surface of a porous brick 1 for an upper nozzle manufactured in a predetermined shape.
Six semicircular pieces of 5R are connected from the space 3 to the horizontal ventilation grooves 10 and are provided at equal intervals. Process and install one at each position m (see Figures 4 and 5), and install the iron plate case 2.
After enclosing the pipe, a pipe for the gas supply pipe 4 was attached, and Samples 1 and 2 of the present invention were obtained. As a comparative example, a porous brick 1 without vertical and horizontal ventilation grooves 9 and 10 was surrounded with an iron plate case 2, and then a pipe for a gas supply pipe 4 was attached as a comparative example 1. The amount of air supplied was changed in sequence and the amount of air discharged over the entire inner hole of the porous brick 1 was measured with respect to the amount of air supplied. The composition and quality results of each sample are shown in Table 1, and the amount of air discharged over the entire inner hole with respect to the amount of air supplied is shown in Table 2. As shown in Tables 1 and 2, Samples 1 and 2 of the present invention are made of porous bricks 1 having almost the same air permeability and provided with ventilation grooves 9 and 10 in the vertical and horizontal directions.
When air is blown from the gas supply pipe 4 at the same pressure, the amount of air discharged over the entire inner hole of the porous brick 1 is approximately 1.7 times that of Comparative Example 1 which does not have the ventilation grooves 9 and 10. In other words, in the case of this invention, for the same discharge amount, it is approximately 1/2.5 ~
It can be seen that the effect can be improved with a small supply amount of about 1/3.

【table】

【table】

[Table] Example 2 Six vertical ventilation grooves 9 were formed on the outer periphery of the side surface of the porous brick 1 for the upper nozzle manufactured in a predetermined shape.
One horizontal ventilation groove 10, width 5m/m, depth 3
m/m semi-elliptical shape, each was processed and provided in the same manner as in Example 1, and after surrounding it with iron plate case 2, a pipe for gas supply pipe 4 was attached, and Sample 3 of the present invention was prepared. Obtained. As a comparative example, a comparative example 2 was obtained in the same manner as in example 1 using a porous brick 1 having no ventilation grooves 9 and 10. Then, nitrogen gas was blown into the porous brick 1 at a constant pressure of 1 kg/cm ² from the gas supply pipe 4 of Sample 3 and Comparative Example 2, respectively.
The discharge amount from the entire surface of the inner hole and the upper half of the inner hole was measured. The blending composition and quality results of each sample are shown in Table 1, and the amount of nitrogen gas discharged from the entire surface of the inner hole and the upper half of the inner hole is shown in Table 3. As shown in Table 3, in Comparative Example 2, only about 1/3 of the total discharge amount was discharged onto the upper side of the inner hole of porous brick 1, where alumina-based inclusions are most likely to adhere, but in Sample 3 of the present invention, It can be seen that the porous brick 1 is discharged almost equally from the upper and lower sides of the inner hole.

[Effect of idea]

(1) When the porous brick 1 having the ventilation grooves 9 and 10 structured according to the present invention is used, the inert gas supplied from the gas supply pipe 4 is distributed in advance to the outer peripheral surface of the porous brick 1 and the surrounding area. It is distributed in the space 3 provided between the iron plate case 2, and is distributed almost uniformly from the upper and lower sides of the inner hole through the vertical and horizontal ventilation grooves 9, 10 and the pores of the porous brick 1. Active gas is discharged,
Conventionally, when casting steel with a high aluminum content, alumina inclusions adhered to the upper side of the inner hole of the upper nozzle, clogging the nozzle and making it difficult to continue operation. By discharging the inert gas almost equally from the upper and lower sides of the inner hole, nozzle clogging can be prevented and the continuation of operation can be extended. (2) It is also possible to prevent alumina-based inclusions attached to the inner hole of the upper nozzle from falling off and being mixed into the steel as large inclusions, resulting in a deterioration in the quality of the steel. (3) Further, the porous brick 1 having ventilation grooves 9 and 10 can be easily formed by processing after firing.
There is no risk of steel leakage due to damage to the upper nozzle.

[Brief explanation of the drawing]

Figures 1 and 2 are longitudinal sectional views of the conventional upper nozzle;
Fig. 3 is an explanatory diagram of the deformation of the iron plate case of the upper nozzle having a gas distribution chamber, Figs. Cross-sectional views taken along arrows A-A and B-B. The symbols in the diagram are as follows: 1...Porous brick, 2...Iron plate case, 3
...space, 4...gas supply pipe, 5...slit, 6...
...through hole, 7... fumarole, 8... gas distribution chamber, 9
...Vertical ventilation groove, 10...Horizontal ventilation groove.

Claims (1)

[Scope of utility model registration request] A space 3 communicating with the gas supply pipe 4 is provided in the lower part between the outer peripheral surface of the porous brick 1 used for the upper nozzle of the sliding nozzle device and the iron plate case 2 surrounding the porous brick 1, and the porous brick A lateral ventilation groove 10 is located on the outer periphery of the side surface of 1 and at a position of 1/4 to 1/2 from the top of the porous brick.
and three to six vertical ventilation grooves 9 communicating the space 3 and the ventilation groove 10 on the outer periphery of the side surface of the porous brick 1, an upper nozzle having an iron plate jacket for a sliding nozzle device .