GB2158380A - Mounting equipment e.g. valve, to molten metal vessel - Google Patents

Abstract

An item of equipment, especially a sliding gate valve (10) for controlling flow of molten metal from a vessel (18) is held between a fixed abutment, e.g. the valve mounting plate (25), and displaceable supporting means in the form of rockers (42) which are biased in the direction of the abutment (25), by spring energy stored in torsion bars (40), to thrust the equipment, e.g. valve plates (11, 12, 15) towards the abutment e.g. into leak-tight face-to-face contact with one another. The torsion bars have central passages through which a fluid e.g. compressed air can pass to keep them reasonably cool. The abutment (25) pivotally mounts side members (27,28) each of which embodies the rockers (42) and torsion bars (40); the side members, when swung into their engaging positions, Fig. 2, are clamped together by means of tie- bolt (34). Various specified alternative devices could be similarly mounted to the vessel instead of the valve specifically embodied. <IMAGE>

Description

SPECIFICATION Auxiliary attachment for molten metal vessels The present invention relates to an auxiliary attachment for molten metal vessels and to a sliding gate valve incorporating such an attachment.

In the latter respect, the invention more particularly concerns an improvement in the means to bias the valve plates into a mutually contacting, leak-tight assembly, the said means comprising torsion elements in a state of stress.

According to the present invention there is provided mounting apparatus for attaching auxiliary equipment to a vessel for molten metal, comprising a fixed abutment formed or carried by a wall of the vessel, two opposed supports and attachment means by which they are articulated to the abutment for hinging movements into or out of operative supporting positions, inwardly-directed displaceable bearer elements coupled by torsion bars to the supports at locations remote from the attachment means, for engaging and thrusting the equipment towards the abutment, and means to move the articulatedly-mounted supports towards one another into operative supporting positions wherein the bearer elements are in displaced positions and torsional stress is exerted thereby on the torsion bars, said stress serving to establish a biasing whereby the bearer elements thrust the equipment towards the abutment.

According to the present invention, there is also provided a sliding gate valve for use in the pouring of molten metals, comprising at least two orificed valve plates for controlling metal flow, a fixed abutment formed or carried by a wall of a vessel for molten metal, two opposed supports and attachment means by which they are articulated to the abutment for hinging movements into or out of operative supporting positions, inwardly-directed displaceable valve plate bearer elements coupled by torsion bars to the supports at locations remote from the attachment means, for supporting and thrusting the valve plates towards the abutment, and means to move the articulatedly-mounted supports towards one another into operative supporting positions wherein the bearer elements are in displaced positions and torsional stress is exerted thereby on the torsion bars, said stress serving to establish a biasing whereby the bearer elements thrust the valve plates towards the abutment.

In preferred embodiments, the fixed abutment is a mounting member e.g. of the valve for securement to the vessel wall.

Hinging of the supports to the abutment facilitates removal, servicing or replacement of the said equipment or of the valve plates of a teeming control valve.

Conveniently, the bearer elements comprise rockers for biasing the auxiliary equipment (or the valve plates in a sliding gate valve) in response to the torsional stress stored in a plurality of torsion bars, each of the latter having one end held non-rotationally and the other end non-rotational with respect to a rocker.

Preferably, the torsion bars are cooled to avoid degradation of their mechanical properties owing to the elevated temperatures of their surroundings. Very effective cooling is possible in the preferred embodiment, wherein the torsion bars are pierced longitudinally for conducting a cooling fluid flow through the torsion bars.

Although in the ensuing detailed description the invention is explained in terms of a sliding gate valve, the invention is of wider application as indicated hereinbefore. Auxiliary equipment of various kinds may need to be attached to a vessel for molten metal e.g. to pass a gas through the vessel wall. The present apparatus can be used to facilitate the mounting of a gas diffuser leaktightly to the vessel. Other equipment mountable to the vessel by means of the apparatus according to the invention include measuring probes, samplers and injection devices for introducing treatment substances to the liquid.

The invention comprehends a vessel for holding molten metal furnished with apparatus as outlined above, such as a valve to control flow of metal from the vessel via a pour opening.

The invention will now be described in more detail, by way of example only, with reference to the accompanying drawings, in which: Fig. 1 is a simplified elevational view schematically showing a sliding gate valve embodying the invention, Fig. 2 is a top plan view of the valve, Fig. 3 is a partially cross-sectioned view of the valve taken on line A-A of Fig. 2, Fig. 4 is a partially cross-sectioned view of the valve but on line B-B of Fig. 2, and Figs. 5 and 6 are views taken on the line C C of Fig. 1 showing two differing rocker arm/torsion bar arrangements.

In the illustrated example, the invention is embodied in a three-plate teeming valve 1 0.

Such valve comprises stationary top and bottom refractory valve plates 11, 12 and a movable central refractory slide plate 1 5 sandwiched therebetween. The bottom plate has a discharge nozzle 1 6 integral with or affixed to its underside. Each of these components 11, 12, 15, 16 is apertured (at 11', 12', 15', 16') for passing molten metal from a vessel when the slide plate 1 5 is positioned with its aperture 1 5' partially or wholly aligned with the other aligned apertures.

The valve can be of the shove-through or reciprocal types. In the former, slide plates of selected form and aperture size are moved successively between the plates 11, 12, each in turn being replaced by a new slide plate. In a reciprocal valve, the slide plate 1 5 is moved to and fro to control teeming. As is known, reciprocal valves can be linearly or rotationally acting and either type can embody this invention.

The slide plate 1 5 can be moved in any convenient way to control teeming: pneumatic, hydraulic and mechanical acutators being common in the art.

The invention is not restricted to three-plate valves as just outlined, but is equally applicable to two plate valves in which the downstream valve plate is the slidable plate.

The valve 10 can be affixed to the bottom of any melt-holding vessel 18 to control flow into a receiver, which may be a mould or another vessel. The meltholding vessel 1 8 could be a vacuum degassing vessel, a tundish or a ladle, for instance. Vessel 1 8 has a pour opening 20 extending through its wall 19, usually in the bottom of the vessel. The valve 10 is mounted to the vessel with the teeming passage thereof aligned with the pour opening 20.

The precise forms of the refractory components 11, 12, 15, 1 6 and the materials from which they are made are not part of the present invention. Accordingly no details are given. Design of these components and selection of their materials are within the purview of the skilled worker in this art.

In order to prevent leakage of melt along routes between confronting faces of the valve plates 11, 12, 1 5 it is necessary to bias them into tight face-to-face contact. It has been common in the art to use coil springs and gas springs acting directly or indirectly between a fixed part of a valve and its set of valve plates. Such springs are relatively complex and costly to manufacture, and coil springs in particular may have very limited lives in that they are prone to weaken during exposure to their high-temperature surroundings. Resort is often had to copious cooling blasts of air. We have been seeking a simpler, cheaper and more reliable alternative to such springs. The valve disclosed herein employs torsion bars as the springs; their benefits and advantages will be apparent from the following description.

As usual, the valve 10 has a fixed abutment formed by a mounting plate 25 which is used to affix the valve to the wall of the vessel 1 8.

Pivotal anchorages 26 articulatingly secure two opposite sides 27, 28 of.the valve to the mounting plate. The sides 27, 28 are tophung on their anchorages 26 and can be swung towards or away from one another about the parallel pivot axes of the anchorages 26. In this particular embodiment of the invention, each side comprises two spacedapart legs 30, which are mounted and pivotable on the anchorages, and a transverse member 31. The latter is secured to the ends of the legs 30 at their free ends remote from the mounting plate 25. As shown, the transverse member 31 of the side 28 incorporates mounting means 33 which pivotally connect with eyebolts 34 employed to secure the sides to one another. The transverse member of the other side 27, has its ends slotted at 36 to receive the eyebolts disconnectibly.In the operative state of the valve 10, nuts 37 on the eyebolts hold the sides close to the lateral edges of the valve plates and the valve plates are biased into leak-tight contact by the stressed torsion bars to be described. The bolts and nuts can be used to draw the sides remote from the mounting plate adjustably towards one another within limits, inter alia to adjust the level of stress in the torsion bars.

Figures 1 to 3 show the general arrangement of the sides and the eyebolts. It will be appreciated that instead of having both eyebolts pivotably attached to one side, each bolt could be pivoted to a respective one of the sides.

The sides comprising legs 30 and transverse members 31 are configured to house the torsion bars 40, to which rocker arms 42 are secured for transmitting spring bias from the torsion bars to the valve plates.

The sides each have two rocker arms, so the lowermost plate 12 is engaged by four rocker arms at points spaced apart along its lateral sides. Two torsion bars 40 act on each rocker arm 42 in the illustrated embodiments.

The torsion bars and rocker arms can be arranged in various ways; two examples are clearly illustrated in Figs. 5 and 6.

The rocker arms 42 have two cylindrical portions 43 apiece, which are journalled in correspondingly-shaped seatings 44 formed between the conjoined legs 30 and arms 31.

By this arrangement, the rocker arms 42 are movable so their arm portions 45 are movable upwardly and downwardly. The cylindrical portions 43 moreover possess non-circular openings receiving an enlarged head portion 48 of an associated torsion bar 40. As shown, the head portion 48 is of hexagonal shape, and is adjacent pne end of the bar 40. A similarly shaped portion 48' is provided at the other end of the torsion bar. The end portion 48' is received in a correspondingly-shaped seating 49 therefor provided by the side 30, 31. So long as the portions 48, 48' and their matching seatings preclude relative rotation, their shapes are immaterial. Cylindrical shapes are permissible if means such as keys or splines are included to prevent relative rotation.

As shown in Figs. 5 and 6, each torsion bar has a stub end 51, of cylindrical shape, adjoining the head portion 48. The stub ends are rotationally received in suitable bearings, viz. sleeves 51A or bearing blocks 51B. The bearing sleeves 51A are clamped in position when the side assemblies comprising legs 30 and transverse members 31 are secured together. The bearing blocks 51 B are undermounted to the side assemblies. The construction of the side assemblies and bearings is designed to facilitate installation and replacement of the torsion bars.

All the torsion bars have central portions of reduced size compared with their enlarged portions 48, 48'. The central portions 50 may, and normally will, be cylindrical.

Moreover, each torsion bar 40 has a bore 52 extending from end to end thereof. The transverse arms 31 each provide for a longitudinal channel 54 which interconnects the torsion bars 40 with an air or gas inlet 56.

In use, let it be assumed that the valve components, other than the plates 11, 1 2 and 15, are positioned as shown in solid lines in Fig. 1. At this stage, the bolts 34 for the sides 27, 28 are disconnected and the sides are pivoted apart on their anchorages 26. The rocker arms 42 and torsion bars 40 are in an unloaded condition.

While the valve sides are pivoted apart, the set of valve plates is inserted between the sides 27, 28. The eyebolts 34 are then swung about their mountings in the associated arm 31 to engage the slots 36, in the other arm 31, the nuts 37 being run back sufficiently for this. Once the sides are loosely connected together by the bolts 39, the valve plates rest upon the underlying rocker arms 42. The aforementioned nuts are then tightened to draw the sides towards one another to their operative pOsitions. As this is done, the rocker arms 42 are deflected in their seatings 44, such deflection being resisted as the torsion bars 40 are twisted. The result of tightening the nuts is accordingly to stress or load the torsion bars 40 such that they force the rocker arms against the lowest plate 1 2 and generate an appropriate spring biasing force thereon.It is the latter biasing which provides the leak-preventing force on the valve plates in the operative condition of the valve.

The bolts 34 optionally carry stops 38 to determine the operative positions of the sides, the corresponding deflection of the rocker arms 42 and the loading of the torsion bars 40. The stops 38 are conveniently screwthreaded to the eyebolts 34. The stops provide a means to ensure the nuts 37 are not inadvertently drawn up so tightly that the sides 30, 31 are caused to foul the valve plates.

It will be appreciated that the combined thickness of the assembled refractory components 11, 12, 1 5 should be slightly more than the distance between the upper bearing surfaces of the rocker arms 42 and the underside of the mounting plate 25 when the torsion bars 40 are unstressed. In the unstressed condition, the said bearing surfaces may be inclined at an angle less than 90 to the side legs 30. That is, the torsion bars 42 may be slightly cocked upwardly. When the torsion bars are stressed operationally, each of the said surfaces will be disposed at a greater angle to the legs 30.

In practice, each torsion bar 40 may be adequately stressed when the rocker arms 42 are deflected through only a small angle perhaps ranging from about 3 to 10 , e.g. 6" to 9 , in the course of tightening the nuts 37 on the eyebolts 34.

It will be appreciated that the biasing force exerted on the valve plate arrangement by a torsion bar, and the angle through which it is deflected upon tightening the said nuts, cannot be specified exactly. These factors will be governed by numerous variables including design, dimensional and geometrical variables as well as by mechanical property variables related to the material from which the torsion bar is made. Those skilled in the art will be aware of the thrust levels to be attained in service for appropriately biasing the valve plates and they will be able to design a suitable valve arrangement without difficulty, aided if need be by routine trial and error experimentation.

Torsion bars as described can be produced speedily and with little fuss from high strength steel bar stock, using machinery no more complicated than a lathe. Their manufacture presents a minimum of difficulty therefore. The manner of their mounting in the sides 27, 28 enables them to be protected well from the ambient high temperatures, so degradation of their mechanical properties is kept effectively in check. Moreover, air cooling by means of the passages 52, 54 is expected to be highly effective, potentially more efficient than air cooling of coil springs, and with a minimum requirement for compressed air.

It may not be immediately apparent, nevertheless a particular advantage of the use of torsion bars is that they enable a valve to be constructed which is very compact, considered in the vertical direction. The aggregate thickness of the valve refractories 11, 12, 1 5 and 1 6 can be minimised, with significant benefits accruing in consequence. Amongst these benefits is the reduced tendency towards valve blockage due e.g. to the build-up of non-metallics such as alumina during teeming.

Essential to the invention are the torsion bars 40 and deflectable or movable plate supports 42 operatively associated therewith.

The plate supports must be free to move to load the torsion bars elastically and to transmit the thus-stored spring energy into plate-biasing force. The simplest way of engineering the necessary movability is by coupling them directly to the torsion bars. Other functionally equivalent constructions may be chosen, however, if design or other considerations so require.

In the illustrated embodiment, the sides 27, 28 are each pivotally suspended and are drawn towards one another by the eyebolts and nuts for adjustably loading the torsion bars to their operative states. This enables one to set their stored torsional energy to a desired level. Alternative constructions are feasible. For example, different means for securing the sides relative to one another could be used, such as appropriate toggle mechanisms.

The supports including the sides 27, 28 could be mounted adjustably to the mounting plate and could comprise part of a carrier frame securable adjustably to the mounting plate.

Toggles could be employed to draw the frame upwardly into an operative position with the torsion bars properly loaded.

One common valve construction has a bottom frame member pivotally connected at one side through pivot links to the valve mounting plate. A toggle mechanism disconnectibly secures the other side of the frame member to the mounting plate. With this construction, disconnecting the toggle mechanism enables the frame member to be hinged away from the vessel to give easy access to the valve refractories for inspection or replacement. Reconnection and overcentring of the toggle mechanism restores the valve to its operative condition with its springs exerting the necessary plate biasing force. It should be appreciated that such a valve could mount deflectable bearers in the form of rockers acted upon by springs in the form of torsion bars, as envisaged by this invention.

Modifications will readily occur to the addressee and it is intended that the following claims shall cover them. One modification which is possible is to make the torsion bars and their associated movable plate supports as an integral component.

Claims (14)

1. Mounting apparatus for attaching auxiliary equipment to a vessel for molten metal, comprising a fixed abutment formed or carried by a wall of the vessel, two opposed supports and attachment means by which they are articulated to the abutment for hinging movements into or out of operative supporting positions, inwardly-directed displaceable bearer elements coupled by torsion bars to the supports at locations remote from the attachment means, for engaging and thrusting the equipment towards the abutment, and means to move the articulatedly-mounted supports towards one another into operative supporting positions wherein the bearer elements are in displaced positions and torsional stress is exerted thereby on the torsion bars, said stress serving to establish a biasing whereby the bearer elements thrust the equipment towards the abutment.

2. Apparatus according to claim 1, wherein the means which move the supports into their operative supporting positions are adjustable whereby adjustment permits setting the torsional stress to a desired operational level.

3. Apparatus according to claim 1 or claim 2, wherein one of the supports is releasably secured to its attachment means by fastening means such as a toggle mechanism, operational torsional stress being maintained in the torsion bars when the fastening means is in an operational securing condition.

4. Apparatus according to any of claims 1 to 3, wherein the attachment means comprise adjustable hinge connections, and/or adjustable fastening means is provided, to permit the supports to be moved towards and away from the abutment to vary the torsional stress exerted on the torsion bars.

5. Apparatus according to any of claims 1 to 4, wherein the means which move the supports into their operative supporting positions comprise drawbolts, a toggle mechanism or like devices which draw the supports remote from the attachment means towards one another.

6. Apparatus according to any of claims 1 to 5, wherein the bearer elements comprise a plurality of rockers for use in supportedly engaging and biasing the said equipment in response to torsional energy stored in a plurality of torsion bars, each of the latter having one end held non-rotationally and the other end non-rotational with respect to a rocker.

7. Apparatus according to claim 6, wherein the torsion bars are pierced longitudinally to pass a cooling fluid flow therethrough.

8. A sliding gate valve for use in the pouring of molten metals, comprising at least two orificed valve plates for controlling metal flow, a fixed abutment formed or carried by a wall of a vessel for molten metal, two opposed supports and attachment means by which they are articulated to the abutment for hinging movements into or out of operative supporting positions, inwardly-directed displaceable valve plate bearer elements coupled by torsion bars to the supports at locations remote from the attachment means, for supporting and thrusting the valve plates towards the abutment, and means to move the articulatedly-mounted supports towards one another into operative supporting positions wherein the bearer elements are in displaced positions and torsional stress is exerted thereby on the torsion bars, said stress serving to establish a biasing whereby the bearer elements thrust the valve plates towards the abutment.

9. A valve according to claim 8, wherein the fixed abutment is a mounting member of the valve, and the two supports are adjustable relative thereto by the attachment means whereby adjustment by said means permits setting the torsional stress to a desired operational level.

10. A valve according to claim 8, wherein the supports are adjustably movable to the operative positions by the means to move the supports towards one another, whereby a desired level of torsional stress is exerted on the torsion bars.

11. A valve according to claim 8, 9 or 10, wherein one of the supports is releasably secured to its attachment means by fastening means such as a toggle mechanism, operational torsional stress being maintained in the torsion bars when the fastening means is in an operational securing condition.

1 2. A valve according to any of claims 8 to 11, wherein the attachment comprising means comprise adjustable hinge connections, and/or an adjustable fastening means is provided, to permit the supports to be moved towards and away from the abutment to vary the torsional stress.

1 3. A valve according to any of claims 8 to 12, wherein the bearer elements comprise a plurality of rockers for biasing the valve plates in response to the torsional stress stored in the torsion bars, each of the latter having one end held non-rotationally and the other end non-rotational with respect to a rocker.

14. A valve according to claim 13, wherein the rockers and their associated torsion bar(s) are integral components.

1 5. A valve according to claim 1 3 or claim 14, wherein the torsion bars are pierced longitudinally and the valve comprises passages for conducting a cooling fluid flow through the torsion bars.

1 6. Sliding gate valves substantially as herein described by way of example.

1 7. A sliding gate valve substantially as herein described with reference to and as shown in the accompanying drawings.

1 8. A vessel for holding molten metal having a pour opening in its wall and a valve according to any of the preceding claims to control flow of metal from the vessel.