AU638369B2

AU638369B2 - Valve plates

Info

Publication number: AU638369B2
Application number: AU90064/91A
Authority: AU
Inventors: Egon Evertz; Jorg Pirdzun
Original assignee: Individual
Current assignee: Individual
Priority date: 1990-12-29
Filing date: 1991-12-24
Publication date: 1993-06-24
Anticipated expiration: 2011-12-24
Also published as: AU9006491A; DE4042203A1; DE4042203C2

Description

II fI 1- F6 38 369 P/00/011 Regulation 3.2

AUSTRALIA

Patents Act 1 990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT

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5* 0 *5 Invention Title: VALVE PLATES The following statement is a full description of this invention, including the best method of performing it known to us: GH&CO REF: P12115-C:CLC

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VALVE PLATE FOR GATE-TYPE VALVES OF METALLURGICAL VESSELS The invention relates to a valve plate for gate-type valves of metallurgical vessels, such as casting ladles and intermediate vessels for the casting of steel, of the kind which optionally according to its slide position, fully releases a stream of liquid metal by a port, throttles it or shuts it off with a closed portion, the port being formed by a ring of refractory material of increased wear resistance inserted in the valve plate.

Such gate-type valves usually consist of a stationary valve plate at the bottom of a casting ladle and a movable valve plate below it, the two valve plates having mutually facing surfaces defining a sealing plane. Each valve plate has at least one port therein for the liquid metal stream, which it can throttle or even cut off as a result of turning or of rectilinear sliding movement of the movable valve plate relative to the stationary valve plate. As a result of this mode of operation, the valve plates mentioned are subject to considerable thermal, ooooo e chemical and mechanical stress, so that the valve plates must often be changed even after a single casting. The wear occurs regularly at the position on the S. circumference of an opening which lies in the direction of the slide path, along which path the column of liquid metal loads the valve plate when the valve plate is moved to its closed position. Therefore, in the case of a valve plate which can be displaced in both directions, the wear phenomena mentioned occur at two mutually opposite positions on the circumference of the opening.

Besides this damage caused by material removal, other damage arises as a result of cracking in the material of the valve plate, which, however, provided the cohesion of the material is preserved, still does not lead to inutility.

In the method of valve plate repair known for example from DE-PS 32 43 305, valve plates are maintained by replacement of the worn refractory material in the region of the opening. Especially, in this connection, a ring consisting of a refractory material of high alumina content can also be inserted within the port which is accordingly enlarged in diameter. Such a ring, however, requires a support so that it cannot be forced out downwards. This can be provided by limiting the ring insert to the zone immediately adjacent to the seal plane, the thickness of the ring being considerably less than that of the remaining valve plate, which supports the ring insert by a shoulder in such a way that a smooth seal plane is preserved. The insertion of a ring is still more effective if, as is known from DE-OS 31 24 359, it passes through the whole overall height of the 'g valve plate. In this case, the inserted ring requires special supporting measures in order not to impair the dimensional accuracy of the seal plane as a result of sinking of the inserted ring. As has become apparent, refractory mortar is unsuitable in view of its S contraction, which has usually to be reckoned with, for *0*C providing sufficient security against the sinking of an inserted ring, if a horizontally-extending vertically- •eloaded gap filled with refractory mortar is present.

Starting from this prior art, the invention is based on s the problem of so constructing a valve plate of the kind S.00 indicated above that vertical displacements of an inserted ring are precluded while at the same time the ring is centred in an improved way.

According to the present invention, there is provided a valve plate for a gate-type valve of a metallurgical vessel, eg a casting ladle or an intermediate vessel for the casting of steel, which optionally according to its slide position fully releases a stream of liquid metal by a port, throttles it or shuts it off with a closed portion, the port being formed by a ring of refractory material of increased wear resistance inserted in the valve plate, wherein an external wall of the ring is provided with a groove which extends along at least a part of the periphery of the surface of the ring, and a corresponding (preferably, mirror image) groove is provided in an inner wall of an opening for the ring in the valve plate so the two grooves together define a cavity which is filled with a refractory mortar which is preferably of the thermally expansive type.

The valve plate constructed in the manner of the invention leads to a locking of the inserted ring in relation to the opening in the valve plate. This locking S. alone can in the simplest case provide a sufficient ieeS resistance to a vertical displacement of the ring. The So ring, which does not need to have a cylindrical external wall but can also be made externally conical or stepped, also receives with its groove a part of the locking provided by the set refractory mortar, the other part S being received by the groove in the internal wall of the 0. valve plate. The refractory mortar, once set, proves to be very durable in the position proposed since in this position is at the greatest possible distance from the load acting on the internal wall of the ring. Its *strength is therefore little impaired by thermal or chemical attack.

55 Especially advantageous in this connection is the use of the thermally expanding refractory mortar. The expansion in the cavity formed by the grooves leads to its being acted on by the expansion pressure, so that an especially reliable immobile seating can be achieved.

The grooves, to be filled with refractory mortar and forming a cavity, are suitably circular in form, corresponding to the ring. The effectiveness of the locking can be increased by providing several such grooves, axially spaced from each other. Suitably in this case, two grooves are chosen. This has the advantage that the clearance existing between the external circumference of the ring and the internal circumference of the opening in the valve plate still has a certain accessibility to the mortar filling the gr6ove.

The cavity mentioned can, in accordance with the form of the groove, be of round, oval or polygonal section. The groove will normally be already filled with refractory mortar composition before the ring is inserted. The accessibility through the clearance spaces, likewise to I be filled with refractory mortar, is especially useful for precise centring.

oe' Possible substances for use in the thermally expanding refractory mortar are especially those which undergo volumetric expansion as the result of thermal crystalline transformation, for example by mullitization, 3mullitization or spinelization. This is achieved especially if an addition of 4 to 6 weight of raw cyanite (disthene) is made to the refractory mortar.

Such a mortar can be processed with 2 water. The particle size distribution of the constituents of the mortar is preferably is characterized by to 85 below 0.09 mm and 15 to 25 between 0.09 mm and 0.5 mm.

The chemical composition will be indicated with the aid of an example, in which the values mentioned are approximate percentages: 87 %A1 2 0 3 4 %CaCO 3 3 P 2 0 0.3 %Fe 2 0 3 5.7 %raw cyanite (disthene).

The already mentioned annular clearance between valve plate and ring arises in the usual way by forming the opening in the valve plate with a somewhat greater diameter than the ring. The centring of the inserted ring is already largely predetermined by the filling of this annular clearance with refractory mortar. It is, however, further stabilized by the clearance mentioned filling up with refractory mortar entering under pressure.

o QO The grooves alone, especially if several are formed, can o already be sufficient, as previously mentioned, to

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,achieve a vertical fixing of the inserted ring. They 5.06 can, however, be used in association with other, known o means for maintaining an immovable seating of the inserted ring. Thus, especially, the external wall of the ring can be made with a step, by means of which it is supported directly, that is without an intermediate layer of mortar, on a shoulder in the wall of the valve plate.

This support can suitably be disposed between the seal plane and the groove, in fact basically always in such a 00 way that the shoulder of the valve plate supports the *o0*9e inserted ring. In this case a smaller radial extension 0:46 of the shoulder and step can be chosen, so that the S. resulting differences in diameter in the ring and in the 68 opening in the valve plate become smaller. Grooves can also be provided which are spaced axially one on each side of the support. In this case also, the installation is such that the valve plate supports the ring by means of the shoulder present in its opening.

For the further illustration of the invention the diagrammatic drawings relating to embodiments are referred to.

Figure 1 shows two different embodiments of a valve plate in longitudinal section, with inserted ring and two grooves, and Figure 2 shows a valve plate in longitudinal section, with inserted ring and a groove.

The valve plate 1 shown in section in Figure 1 can have different forms. The section of the drawing to the right of the axis of symmetry 16 shows an inserted ring 6 with cylindrical outer surface to which a likewise cylindrical inner wall 19 of valve plate 1' corresponds. The outer wall of the ring 6 has a pair of axially spaced grooves therein, the lower of which is indicated by 18. These ""grooves lie opposite respective correspondingly shaped oSSO *grooves in internal wall of the valve plate 1i', the upper 0O*S ~of which grooves is numbered 17. The two grooves are o filled with a refractory mortar, which is represented by black circular areas without reference number.

The left-hand part of Figure 1 shows a valve plate 1 whose internal wall is stepped to define a shoulder which @5 supports a step 25 of the ring 5. The ring 5 is provided with one groove above and one below this step, the reference number 7 indicating the lower of these.

S. Correspondingly shaped grooves, of which the upper is *indicated by reference number 4, are provided in the S internal wall of the valve plate i. The cavities formed by the co-operating pairs of grooves are filled with refractory mortar as in the embodiment corresponding to the right-hand part of Figure 1. An annular gap 20 is provided which also contains some of the refractory mortar filling the co-operating grooves. This serves to centre the ring In this way, sealing plane 2 between the valve plate 1 and the overlying valve plate (not shown) takes the form of a smooth surface so that, when sliding the valve plate relative to the overlying plate, no liquid steel can be carried along, and corresponding operational dangers are avoided. In addition, the loading arrow 26 indicates the direction in which the steel flows through the valve plate and in which, on throttling or sealing off the latter, loads arise. These loads are determined not only by the steel load on the valve plate but also by vibrations, whose force cn be considerably greater.

In the embodiment according to Figure 2, a valve plate 9 for the bottom of the metallurgical as well as a valve plate 10 for operating the nozzle are shown. In the valve plate 9, a ring 11 is inserted, while the valve plate 10 supports a ring 12. For simplicity, only the half of the drawing to the right of the symmetry axis 000S 0 is shown. Both the valve plate 9 and the valve plate are designed with internal shoulders 22 and 21. Between these internal shoulders, which support steps 23 and 24 of the corresponding rings 11 and 12 respectively, and each of the external sides remote from the seal plane, S there are grooves 13 and 14 in the valve plates. There *S t are also corresponding grooves in the outer walls of the inserted rings 11 and 12. Into all these grooves as well S"as into clearances 20 between each ring and the respective valve plate, there is forced a refractory .mortar which leads both in the hydraulic state and in the subsequent ceramically set state to the intended locking o of the inserted rings with regard to vertical displacements. As in the previous embodiment, liquid steel flowing through acts in the direction of the arrow 26 and the assembly is exposed to the action of mechanical vibrations. The proposed type of locking does not, however, permit the rings to move vertically out of their valve plates, so that the seal plane remains smooth.

Claims

2. A valve plate as claimed in claim i, wherein a 0000o 00 ~clearance is provided between the Outer surface of the ring and the wall of the opening in which the ring is S-inserted, and the mortar at least partially fills the clearance so that the ring is centred in the opening by the mortar. oooo S 3. A valve plate as claimed in claim 1 or 2, wherein 0009 the grooves are circular corresponding to the ring. 0 4. A valve plate as claimed in any preceding claim, 000 wherein several axially spaced grooves are provided.
5. A valve plate as claimed in any preceding claim, S. wherein the ring has a surface which, except for the groove grooves therein, is cylindrical and the wall of the opening is likewise cylindrical. 6 A valve plate as claimed in any preceding claim, wherein the mortar is thermally expansive.
7. A valve plate as claimed in any preceding claim, wherein the refractory mortar contains 4 to 6 weight of cyanite (disthene).
8. A valve plate as claimed in any preceding claim, wherein, in the axial direction, between a sealing plane of the valve plate and the groove, the external wall of the ring has a step by means of which the ring rests on a shoulder in the wall of the opening in the valve plate.
9. A valve plate as clai-ed in any preceding claim, wherein two axially spaced grooves are provided in the ring.
10. A valve plate as claimed in claim 8, wherein two axially spaced grooves are provided in the ring, the grooves being disposed on opposite sides of the step. o o
11. A valve plate as claimed in claim 1, substantially as hereinbefore described with reference to Fig 1 or Fig 2 of the accompanying drawings. Dated this 24th day of December 1991 EGON EVERTZ By his Patent Attorneys GRIFFITH HACK CO. f ABSTRACT A valve plate 1 for gate-type valves of metallurgical vessels has an opening therethrough in which a ring 5 of refractory material mounted with clearance. The external surface of the ring 5 is provided with at least one groove 7 therein. The opening has at least on correspondingly shaped groove 4 therein so that the respective grooves 4 and 7 together define a cavity in which a thermally expansive refractory mortar is provided to hol,. and centre the ring 1 in the opening. This arrangement permits the plane of slide 2 of the plate 1 to be smooth (Fig 1). e !6 i e go 4 .J J* 0 a) g rl