GB2153977A

GB2153977A - Sliding gate valves

Info

Publication number: GB2153977A
Application number: GB08502636A
Authority: GB
Inventors: Bernhard Tinnes
Original assignee: Metacon AG
Current assignee: Metacon AG
Priority date: 1984-02-02
Filing date: 1985-02-01
Publication date: 1985-08-29
Also published as: ZA85813B; FR2559081A1; DE3403522A1; IT8547606A0; JPS60166162A; BE901609A; GB8502636D0

Abstract

A sliding gate valve 5 for controlling the flow of molten metal includes two wear parts, e.g. a sliding plate 8 and a sleeve 9, through which coaxial flow openings extend for the passage of the molten metal. One wear part 8 has an external surface of revolution 8a which engages and forms a seal with an internal surface of revolution 9a on the other wear part 9. At least one of the surfaces of revolution is curved in longitudinal section. <IMAGE>

Description

SPECIFICATION Sliding gate valves The invention relates to sliding gate valves for controlling the flow of molten metal, in particular molten steel, and is concerned with adjacent refractory wear parts for such valves, such as sleeves, plates and tubes, which have a flow opening therein for the flow of molten metal and in particular with the sealing of such wear parts.

As is disclosed in, for example, U.S. Patent No. 3841539, it is usual to seal the loosely engaging wear part, such as plates and sleeves of sliding gate valves with mortar at their point of connection and to enclose them with a metallic housing. Mortar joints inherently seal relatively reliably but have the disadvantage that if one of the connected wear parts wears out more quickly, e.g. the outlet sleeve wears more quickly than the valve plate, which are both generally constructed to be metallically disconnectable, it is difficult to mount the new component after the old component has been broken away. Thus a certain amount of the sealing mortar adheres to the remaining wear part which must be removed in a tedious and time consuming operation before the new wear part can be positioned and a new layer of mortar applied.

German Offenlegungsschrift No. 1 7 58 960 discloses the sealing of two refractory components of which one has a spherical curved concave surface and the other a correspondingly shaped convex surface, by pressing the two components together. However, such a seal cannot be used with wear parts for sliding gate valves, particularly because the differing thermal stresses in the individual wear parts would rip open the relatively large sealing surfaces.

It is an object of the present invention to provide a mortarless, gastight seal for connected wear parts in a sliding gate valve, especially for two wear parts which experience has shown have differing service lives, which seal permits a certain inclination of the wear parts to their longitudinal axes.

According to the present invention there is provided two parts for a sliding gate valve for controlling the flow of molten metal, through which wear parts coaxial flow openings extend for the passage of the molten metal, one wear part having an external surface of revolution which engages and forms a seal with internal surface of revolution on the other wear part, at least one of the surfaces of revolution being curved in longitudinal section.

The wear parts in accordance with the present invention can be manufactured very simply and connected together both rapidly and reliably without the necessity of applying mortar. The peripheral seal which is produced between the wear parts can withstand greatly differing thermal stresses at the engaging ends of the wear parts without difficulty, that is to say the seal remains gastight even when the wear parts are subjected to differing operational conditions and furthermore will permit a slight subsequent realignment or relative movement of the wear parts.

The centre of the curved surface of rotation or of at least one of the curved surfaces of rotation preferably lies on the axis of the flow openings when viewed in longitudinal section.

The engagement of the two wear parts preferably occurs within the region defined by lines extending through the said centre at 20 and 70 from the axis of the flow openings. It is in this region that there is a risk that one of the wear parts or the sealing region thereof may be damaged by thermal stresses and the construction of the present invention substantially eliminates this risk.

The contact between the surfaces of revolution may be a line contact or alternatively it may be a band or strip contact. In the latter case in which both the surfaces of revolution are curved in longitudinal section and have the same radius, at least at the region in which they engage, it is preferred that the surfaces engage over a length which is not more than half the length of the said region when viewed in longitudinal section. It is preferred that the surfaces of revolution also have the same radius beyond the region over which they engage one another.

Further features and details of the invention will be apparent from the following description of certain specific embodiments which is given by way of example with reference to the accompanying schematic drawings, in which: Figure 1 is a longitudinal sectional view through a sliding gate valve on a metallurigical ladle; Figure 2 is a view similar to Fig. 1 of a sliding gate valve on a tundish; and Figures 3 to 6 are scrap sectional views of various possible seals between the refractory wear parts on an enlarged scale.

Referring first to Fig. 1, a pouring ladle 1 for steel has a sheet metal shell 2, a refractory lining 3 and a nozzle brick 4, downstream of which is a sliding gate valve 5. The valve 5 has an inlet sleeve 6, a fixed plate 7 a sliding plate 8 and an outlet sleeve 9 which is movable together with the valve plate 8 in a support frame 10 in order to start, stop or regulate the outflow of the melt. In order to throttle the stream of molten metal, e.g. when the ladle is full when beginning pouring, the outlet sleeve 9 has a displaced flow opening in order to protect the valve plate from premature wear. If required, this sleeve can be replaced by a sleeve of different cross-section.

The sleeve is secured in position by means of a metallic sleeve coupling 11 which is bayonet-connected to the support frame 1 0.

The seal between the outlet sleeve 9 and the valve plate 8 is mortarless in that a frustoconical projection 8b on the plate 8 engages an internal surface of rotation 9a of circular arcuate profile on the sleeve 9. The surfaces cooperate to form a peripheral line seal.

Fig. 2 illustrates a tundish 1 2 for teeming molten steel into ingot moulds which includes a sheet metal sheel 13, a refractory lining 14 and a nozzle brick 1 5 to which a sliding gate valve 1 6 is connected. The valve has an inlet sleeve 17, a fixed base plate 18, a sliding plate 20 movable by means of support frame 19 and a lower plate 21 to which an outlet sleeve 22 is connected, the plate 21 and sleeve 22 being carried by a common frame 23. This frame has a flange 24 to which a teeming tube 25 is connected by means of a support cage 26 and a wedge connection 27.

In use, the teeming tube extends into an ingot mould (not shown). The seal between the outlet sleeve 22 and the teeming tube 25 is effected, as in the embodiment of Fig. 1, by means of surfaces of rotation 22a and 25a which engage one another and form a peripheral line seal. However, in this case, the surface 22a which is arcuate in profile is provided on the outlet sleeve 22, i.e. on the wear part which extends into the other wear part, and the funnel-shaped surface 25a is provided on the wear part which receives it, i.e. the teeming tube.

The mortarless seal of Fig. 2 is shown on an enlarged scale in Fig. 3 from which it is clear that the peripheral line seal effected by the surfaces of rotation 26a and 27a on the engaging wear parts 26 and 27 lies in an angular region 28 defined by two radii 29 and 30. Both radii belong to a circle 31 traversing the peripheral seal and intersect on the rotational axis 32 of the surfaces of rotation 26a and 27a. Measured from the rotational axis 32, the angular region 28 is positioned between the 30) and 70 positions.

Fig. 4 illustrates a modified construction of seal between a wear part 33 which affords an internal surface of rotation 33a which is circular in longitudinal cross-section with its centre lying on the axis of rotation 32. The engaging wear 34 has a projection whose surface is a surface of rotation 34a whose radius is smaller than that of the surface 33a. The peripheral sealing may thus be thought of as spherical in profile with its line seal contact within the said angular region.

In the modification if Fig. 5 the peripheral seal is effected over a larger area, i.e. the two surfaces of rotation 35a and 36a of the engaging wear parts 35 and 36, which are centered about the axis 32 and have the same profile, touch one another and seal over an area of strip or band shape, the width of which strip or band corresponds to the length of the surface 36a in longitudinal section.

Here too, the sealing is effected in the said angular region but the width of the band is at most half the distance between the 30 and 70 angles at the sealing area.

The relative disposition of the sealing surfaces in Fig. 5 may be reversed as in Fig. 6 in which the wear part 37 which affords the recess carries the narrow surface of rotation 37a which cooperates with the larger surface of rotation 38a of the wear part 38 which extends into the recess.

It will be appreciated that the surface of rotation may have an elliptic, parabolic or other curved profile instead of the circular profile shown in the examples.

Claims

1. Two wear parts for a sliding gate valve for controlling the flow of molten metal.

through which wear parts coaxial flow openings extend for the passage of the molten metal. one wear part having an external surface of revolution which engages and forms a seal with an internal surface of revolution on the other wear part, at least one of the surfaces of revolution being curved in longitu dinal section.

2. Wear parts as claimed in claim 1 in which the centre of the curved surface of rotation or of at least one of the curved surfaces of rotation lies on the axis of the flow openings when viewed in longitudinal section.

3. Wear parts as claimed in claim 2 in which the engagement of the two wear parts occurs within the region defined by lines extending through the said centre at 20 and 70 from the axis of the flow openings.

4. Wear parts as claimed in claim 3 in which both the surfaces of revolution are curved in longitudinal section and have the same radius at the region in which they engage and engage over a length which is not more than half the length of the said region when viewed in longitudinal section.

5. Wear parts as claimed in any one of claims 1 to 3 in which both the surfaces of revolution are curved in longitudinal section but have differing radii.

6. Wear parts as claimed in any one of claim 1 to 3 in which one surface of revolution is curved and the other is straight in longitudinal section.

7. Two wear parts for controlling the flow of molten metal substantially as specifically herein described with reference ro Fig. 1 or Figs. 2 and 3 or any one of Figs. 4, 5 and 6 of the accompanying drawings.

8. A sliding gate valve for controlling the flow of molten metal including two wear parts as claimed in any one of the preceding claims.