EP0563376B1

EP0563376B1 - Gaz blowing plate brick or nozzle brick for molten metal

Info

Publication number: EP0563376B1
Application number: EP89906468A
Authority: EP
Inventors: Takashi Otsuka; Kenji Yamamoto; Mototsugu Osada; Tado Taniguchi; Yoshifumi Shigeta;
Original assignee: Shinagawa Refractories Co Ltd
Current assignee: Shinagawa Refractories Co Ltd
Priority date: 1989-06-01
Filing date: 1989-06-01
Publication date: 1997-03-05
Anticipated expiration: 2009-06-01
Also published as: DE68927834D1; DE68927834T2; WO1990014908A1; KR960005885B1; EP0563376A4; BR8907894A; AU3746889A; AU652916B2; EP0563376A1

Abstract

This invention relates to a gas blowing plate brick or nozzle brick for a molten metal ejector, characterized in that the plate brick or nozzle brick is divided into at least two segments in the horizontal direction with a plurality of small-diameter pipes arranged fixedly in a sealed state in the dividing surfaces. Each brick is capable of preventing the leakage of a gas blown into the above-mentioned kind of apparatus, and carrying out a stable casting operation, and renders it unnecessary to carry out troublesome, expensive additional steps, such as a brick cutting step, a brick boring step and a brick connecting step.

Description

This invention relates to an inert gas injecting plate brick or insert nozzle brick for use in a sliding gate valve apparatus of molten metal as defined in the preamble of claim 1.

BACKGROUND TECHNIQUE

In a continuous casting installation, the molten metal received in a ladle is poured into a mold through a tundish. At such a time, a certain amount of molten metal is kept stored within the tundish before starting the pouring of the molten metal into the mold at the beginning of casting, and after the flowing-up of impurities a nozzle is opened to start the pouring. This procedure is called a closed start, and these days this technique has now been introduced.
In the closed starting of a continuous casting tundish, various systems have been proposed for injecting an inert gas to prevent the molten metal from solidification within the nozzle while storing the molten metal in the tundish by closing the nozzle hole of a sliding porous refractory. A system has been proposed (shown in Fig. 8 - Japan Patent Kokai No. 177952/85) in which a gas injecting ring is arranged, said ring having a plurality of small radial orifices provided toward the slide plate side from a groove formed along the outer periphery within the opening of a bottom plate brick to the center of the opening.
The document JP-A-53-123 336 discloses an inert gas injecting plate brick or insert nozzle brick for use in a sliding gate valve apparatus of molten metal, in particular for a closed start pouring system, wherein an amount of molten metal is stored in a tundish prior to pouring the molten metal into a mold at the beginning of casting, wherein the sliding gate valve is provided with a pipe for gas injection. The sliding gate valve apparatus is provided with an inert gas injecting plate, wherein a plate is provided with a tube for injecting gas. For this purpose the brick forming the plate is provided with a corresponding boring to receive the pipe.
The document JP-A-61-195 734 discloses a nozzle for manufacturing composite matter wherein a plurality of pipes for blowing in an inert gas are embedded and placed in a molten metal nozzle made of a refractory material. These pipes can be connected to a gas chamber which is provided along the periphery of the outer wall of the nozzle and is connected to a gas supply source. Again, the tubes are inserted into borings provided in the nozzle.
The known systems have the following drawbacks:

a) The gas guiding pipe (made of copper or steel) is connected and sealed with the gas feeding holes (made of brick bored with fine orifices) by means of sealing material, mortar or soldering, and in the high temperature condition the gas sometimes leaks (shown with x marks in Fig. 8) from the joints so as not to be injected properly into the nozzle opening.
Further, practically the gas amount injected into the nozzle opening becomes irregular so that casting is often not stable in operation whereby the products and the quality thereof are not uniform.
b) The making process requires additional working such as a cutting processing of brick, a boring processing of brick, and a jointing working of the gas guiding pipe and the gas injecting brick so that high cost are caused thereby.

DISCLOSURE OF THE INVENTION

The inventors of this invention have made extensive studies and researches to solve the various problems innate in the known systems, and as the result, they have been successful in developing a novel inert gas injecting plate brick or insert nozzle brick for use in a sliding gate valve apparatus of molten metal, which brick is of quite different idea from the known systems.
Hence, the object underlying the present invention is to provide an inert gas injecting plate brick or insert nozzle brick for use in a sliding gate valve appratus of molten metal which can be produced in a simple process and offers a high reliability in operation for supplying gas.
This object is solved in a satisfying manner by an inert gas injecting plate brick or insert nozzle brick of the type specified above which is characterized in that the plate brick or insert nozzle brick is horizontally split into at least two parts which form split surfaces between each other, in that a plurality of small diameter pipes are provided which are sealingly arranged and secured in the respective split surfaces, and in that the small-diameter pipes are in communication with an external connecting port to a gas source and have their injecting openings opening into a melt passing hole.
According to a further development of the inert gas injecting plate brick or insert nozzle according to the invention, the small-diameter pipes are bundled in a group or a plurality of groups which communicate with the connecting port of a gas source and the melt passing hole.
In a still further development of the inert gas injecting plate brick or insert nozzle brick of the invention, the small-diameter pipes are disposed along lines which, when viewed from above, extend perpendicularly or angularly with respect to the melt passing hole, wherein the small-diameter pipes are provided in planes which are perpendicular or inclined with respect to the melt passing hole so that they open horizontally and/or obliquely upwards and/or downwards into the melt passing hole.
In a specific embodiment of the inert gas injecting plate brick or insert nozzle brick of the invention, the small-diameter pipes are made of metal or ceramic.
According to a further development of the inert gas injecting plate brick or insert nozzle brick of the invention, the brick is provided with at least one through hole each of which is provided with small-diameter pipes for injecting gas.
In a still further development of the inert gas injecting plate brick or insert nozzle brick of the invention, one of the parts is provided with grooves receiving the plurality of small-diameter pipes, and the other of the parts opposite thereto is formed without grooves.
The present invention is technically constituted such that a plate brick or insert nozzle brick for use in an apparatus of discharging molten metal is split into at least two parts horizontally, said split surfaces are provided with a number of small diameter pipes (2) in the sealed state, and said pipes are secured to said split surface, and said small diameter pipes are communicated with a gas passing portion. By means of such technical constitution it is possible to achieve the undermentioned function and effect.

a) The gas passing route where gas is likely to leak and where the temperature is likely to rise in the vicinity of the nozzle opening, is made in one body without joints so that the gas does not leak out, and therefore, the whole gas as fed is injected into the nozzle opening.
b) After the formation of the plate brick or nozzle brick by pressing, the additional working such as a cutting processing or a boring processing is no longer required, so that cost decreases.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 shows one embodiment of the invention, in which the gas guiding pipes are incorporated in the normal direction of and obliquely downward to the nozzle opening of the plate brick, Fig. 1a is a partly notched plan view; Fig. 1b is a vertical sectional view taken along the A-A line of Fig. 1a;
Fig. 2a and Fig. 2b are also a plan view and a vertical sectional view, similar to Fig. 1, which show a different embodiment of the invention, in which the gas guiding pipes are incorporated in the normal direction of and obliquely downward to the nozzle opening of the plate brick;
Fig. 3a and Fig. 3b show an embodiment of the gas guiding pipes (in the case of a plurality) which are incorporated in the brick, and Fig. 3b is a sectional view taken along the A-A line of Fig. 3a;
Fig. 4a and 4b show an embodiment in which the gas guiding pipes are incorporated in an insert nozzle brick, and Fig. 4a is a vertical sectional view while Fig. 4b is a lateral sectional view taken along the A-A line of Fig. 4a;
Fig. 5 is a partly sectional side view showing the respective members in the embodiment of Fig. 1;
Fig. 6a and Fig. 6b are views, similar to Fig. 4, of an example of a three-split type, where the present invention is applied to the insert nozzle brick;
Fig. 7 is a vertical sectional view of an embodiment of a three-split type, where the invention is applied to the plate brick; and
Fig. 8 is a vertical sectional view of a bottom plate brick for the injection of inert gas of a known system.

BEST EMBODIMENT FOR CARRYING OUT OF THE INVENTION

The invention will now be described more in detail, by way of embodiment, with reference to the accompanying drawings.
Fig. 1 shows an embodiment in which the present invention is applied to a bottom plate brick. As shown, said plate brick is split into bricks 3 and 4, a number of small-diameter pipes 2 each having a connecting port 1 to the gas source are involved and arranged in the jointing surfaces of said split bricks 3 and 4, and gas injecting openings 5 of said small-diameter pipes 2 in group communicate with the melt passing hole.
Fig. 2 is similar in construction to Fig. 1, and it is an embodiment in which the gas injecting direction of the small-diameter pipe 2 is brought close to the normal direction of the outer periphery of the melt passing hole. Fig. 2 is similar to Fig. 1 in other constitution.
Fig. 3a is a plan view showing an assembling mode of the group of said small-diameter pipes 2, and Fig. 3b shows a sectional view of the group of said small-diameter pipes 2 in the bound state.
Fig. 4 is an embodiment in which the present invention is applied to an insert nozzle brick. In this embodiment, the insert nozzle brick is split into bricks 3 and 4, a group of the small-diameter pipes 2 are involved and arranged, similarly to the above, in the split surfaces, and gas injecting openings 5 communicate with the melt passing hole.
Fig. 5 is a sectional view where respective parts in the embodiment of Fig. 1 are separately shown thereby to exemplify their arranging relationship.
Fig. 6 shows an embodiment in which the insert nozzle brick is split into three parts (3, 3' and 4), and the gas injecting openings 5 are disposed in two rows of upward and horizontal directions in the melt passing hole.
Fig. 7 shows an embodiment in which similarly, the insert nozzle brick is split into three parts (3, 3' and 4), and the injecting openings 5 are disposed also in two rows up and down.

FUNCTIONS

A plate brick or an insert nozzle brick which is used in a sliding gate valve apparatus of molten metal is split into two or more parts, several slender stainless or copper pipes are arranged in the split surfaces toward the nozzle opening, and thereafter the split plate bricks or insert nozzle bricks are adhered with mortar or the like.

1) One of the two split bricks is press formed by providing grooves 10 for embedding the pipes. The brick material is a high alumina or alumina carbonaceous one which is generally used as plate brick or insert nozzle brick. Additionally, in the case of pipes the outside diameter of which is thinner than the mortar joint, it is unnecessary particularly to provide grooves for embedding the pipes.
2) The other of the two split bricks is not provided with the grooves for embedding the pipes, and it consists of a press formed article or a casting material. The material is the same as in 1) above.
3) For making a gas guiding pipe, a copper or stainless pipe of about 0.2 - 3.00 mm inside diameter is bend worked in advance to meet the shape of the groove of the brick. In the case of a plurality of pipes, they are assembled in a single pipe by soldering or the like and a nipple for connection is secured to the tip of said assembled pipe.
4) In the case of a plurality of pipes, the inside diameter, length and securing position of each of the pipes are varied in consideration of the pressure loss caused by the difference of the lengths of the respective pipes, so that the gas may be injected uniformly into the nozzle hole.
5) In order that the pressure loss of the pipes is decreased, the inside diameter of the pipes is made larger except the gas injecting port portions of the pipe. Further, in case the pipes are two or more, they are combined and connected to a single larger pipe whereby the pressure loss is decreased (see Fig. 3).

EFFECTS OF THE INVENTION

(1) Since the inert gas fed into the pipes passes through a jointless piping so as to be injected into the nozzle hole, the gas cannot be leaked and it is possible to feed the gas in a certain amount.
In known techniques, for example, a cylindrical brick bored with fine orifices was set to a plate brick and a metallic pipe was connected to the gas reservoir provided therebetween. However, gas leakage could not be prevented being affected by the heat generated from the molten metal when casting.
(2) Since the plate brick itself does not form a part of the gas passing route it is unnecessary that the brick is machine worked to form a gas passage there. Because of this, the brick as press formed can be used as it is to allow the manufacturing process to be simplified. This leads to cost lowering.
(3) By varying the size, number, position and angle of the pipes it is possible to easily manufacture bricks of the constructions suited for closed start and blocking prevention respectively.

Claims

An inert gas injecting plate brick or insert nozzle brick (3, 4) for use in a sliding gate valve apparatus of molten metal, in particular for a closed start pouring system wherein an amount of molten metal is stored in a tundish prior to pouring the molten metal into a mould at the beginning of casting, wherein the sliding gate valve is provided with a pipe for gas injection,
characterized in that the plate brick or insert nozzle brick (3, 4) is horizontally split into at least two parts (3, 3' and 4, respectively) which form split surfaces between each other,
in that a plurality of small diameter pipes (2) are provided which are sealingly arranged and secured in the respective split surfaces,
and in that the small-diameter pipes (2) are in communication with an external connecting port (1) to a gas source and have their injecting openings (5) opening into a melt passing hole.
The inert gas injecting plate brick or insert nozzle brick (3, 4) according to claim 1,
characterized in that the small-diameter pipes (2) are bundled in a group or a plurality of groups which communicate with the connecting port (1) of a gas source and the melt passing hole.
The inert gas injecting plate brick or insert nozzle brick (3, 4) according to claim 1 or 2,
characterized in that the small-diameter pipes (2) are disposed along lines which, when viewed from above, extend perpendicularly or angularly with respect to the melt passing hole,
wherein the small-diameter pipes (2) are provided in planes which are perpendicular or inclined with respect to the melt passing hole so that they open horizontally and/or obliquely upwards and/or downwards into the melt passing hole.
The inert gas injecting plate brick or insert nozzle brick (3, 4) according to any of claims 1 to 3, characterized in that the small-diameter pipes (2) are made of metal or ceramic.
The inert gas injecting plate brick or insert nozzle brick (3, 4) according to any of claims 1 to 4, characterized in that the brick (3, 4) is provided with at least one through hole each of which is provided with small-diameter pipes (2) for injecting gas.
The inert gas injecting plate brick or insert nozzle brick (3, 4) according to any of claims 1 to 5, characterized in that one (4) of the parts (3, 4) is provided with grooves (10) receiving the plurality of small-diameter pipes and the other (3) of the parts (3, 4) opposite thereto is formed without grooves.