A GATE VALVE

Abstract: The present invention relates to a gate valve for a casting die in which an article is to be cast under heat and pressure. According to the invention the valve incorporates a rotatable steel disc or plate (11) having an opening (19) which is located eccentrically in relation to the axis of rotation (A-A) and which in a first position of rotation is in register with the casting material inlet opening (10) to the die cavity, and which in a second position of rotation lies on one side of and outside the inlet opening, the steel disc covering the die-cavity inlet open­ ing (10) in this second position of rotation. A valve constructed in accordance with the invention results in a considerably shorter sprue in the die-filling pas­ sage subsequent to hardening of the casting material in the die.

Description: A gate valve The present invention relates to a gate valve according to the pre characterizing clause of Claim 1. Sinks, wash basins and like equipment can now be manufactured to advantage from polymer materials together with ballast, with the aid of die-casting or moulding techniques. One such polymer material comprises 70% silica sand of cristobalitic structure admixed with polymer binders. Preferably, the curing agent used in the mixture comprises organic peroxides which cause the mixture to harden at elevated temperatures, e.g. 900C. The time taken for the mixture to harden is from 15-45 minutes, depending upon the composition of the curing agent, during which time the cast article remains in the die. Manufacture is carried out by mixing the starting materials at room temperature and then introducing the resultant mix into a pressure tank. The tank is then placed under a pressure of about 2 bars, for example with the aid of air under pressure. The mix is then passed through conduits from the tank into the die tool, which normally comprises an upper and a lower die part, between which the article is formed under pressure. The casting material is introduced into the die from beneath, and when producing, e.g., sinks, the die halves are placed sc that the sink is cast on end. As the die is filled with casting material from beneath, the air present between the die halves is released through an air ventilating valve. The casting material is injected into the die until it reaches the ventilating valve. In order to obtain a product which is as compact as possible with maximum surface smoothness, the die is placed under pressure, with the aid of hydraulic rams, during the time taken for the material to harden or set. In this case, the pressure should reach 10 bars. It has been found that due to the transfer of heat from the heated die halves, the material also solidifies along part of the filling pipe or inlet passage, to form a flash or stalk. Since it is practically impossible to remove this hardened material flash or stalk, it has been necessary hitherto to use a heavily reinforced plastic hose in the inlet passage. This hose has been divided into two sections, with an intermediate conduit, preferably exhibiting a conical throughpassage. Prior to pressurizing the die, the one hose section is folded back through 0 an angle of 180 and a ring is forced over the fold. The other hose section is then folded in a similar manner and sealed with a further ring. It has been possible to withstand the die pressure during the hardening or setting period, by using a sufficiently powerful hose. At least the hose section nearest the die has to be scrapped upon completion of a die-casting operation. The cost of the hoses naturally has a negative influence on the profitability of the product. In order to eliminate these drawbacks there is provided in accordance with the invention a gate valve for use with dies or moulds in which articles are to be cast under pressure, this gate valve having the characteristic features set forth in the characterizing clause of Claim 1. The invention provides a gate valve which leaves on the casting only a relatively shallow flash, which can be readily ground away without requiring any part of the system to be scrapped. A gate valve constructed in accordance with the invention also contributes towards simplifying manufacturing procedures. These and other advantages will be made more apparent in the following description of a gate valve according to the invention, made with reference to the accompanying drawings, in which Figure 1 is a cross-sectional view of a gate valve according to the invention, with the plunger in an open position; Figure 2 is a side view, partly in section, of a tubular element incorporated in the valve of Figure 1 with a lever arm in the closing position of the plunger; Figure 3 is a sectional view taken on the line III-III in Figure 2; and Figure 4 is a cross-sectional view, in larger scale, of the part of the valve located nearest the die cavity. The gate valve according to the invention is journalled on a cylindrical sleeve-like element 2 for rotation about an axis A-A. One end of the sleeve-like element 2 is screwed firmly in a well 4 or like cavity of one die half, by means of screw-threaded bolts 3, of which one is shown in Figure 1 and Figure 4. The other end of the sleeve-like element, i.e. its lower end, is fitted with the aid of a ring flange 5 into an opening located in the inner wall 1 of the relevant die half, preferably the lower die half. The sleeve-like element 2 also incorporates an inwardly projecting peripheral flange 6, which connects the lower cylindrical end of the element with the ring flange 5. Arranged inwardly of the ring flange 5 is a steel plug 7, the lower end of which extends to the inner surface of the inner wall of the die half. This Ig has an outwardly projecting peripheral flange which extends outwards above the peripheral flange 6 on the sleeve-like element so as to contact the inner surface of said element.Located above the plug 7 is a Teflon disc or plate 8 which, together with the plug, is non-rotatably held to the peripheral flange of the element 2 by means of a locking pin 9, which passes through the Teflon disc and the peripheral flanges of the steel plug and the sleeve-like element. A material inlet opening 10 which diverges in a direction towards the die cavity is formed in the steel plug and the Teflon disc, and positioned eccentrically in relation to the longitudinal axis of the sleeve-like element 2. Arranged above the Teflon disc 8 is a steel disc or plate 11, which is 'affixed around its periphery, preferably by gluing, to a sleeve 13, which is preferably made of brass. The steel disc 11 encircles a bead-like part of a body 12, suitably made of hardened steel. The body 12 is provided with an annular flange which is joined to a further sleeve 14, for example welded thereto. The sleeve 13, which adjoins the steel disc 11, extends within the sleeve-like element 2 and presents at its upper end an outwardly extending peripheral flange 15, which slideably fits into a groove provided in the end of the sleeve like element attached to the well 4. As will be seen from the Figures, this end of said element forms a part comprised of one or more separatable elements. The sleeve 14, which extends from the steel body 12 upwardly beyond the upper end of the sleeve-like element 2, carries on the upper end thereof a tubular element 16, which will be described in more detail hereinafter. The sleeve 14 has located on a level with the upper end of the sleeve-like element a guide shoulder 14 which slides in a guide groove located in the sleeve-like element above the groove accommodating the peripheral flange 15 of the sleeve 13. The sleeves 13 and 14 are connected together, for example, by means of locking pins 18. Thus, the sleeves can rotate together around the axis A-A, and the rotational movement can be restricted, for example, by suitable design of the guide groove in the sleeve-like element receiving the guide shoulder 17. The steel body 12 has provided therein a cylindrical opening 19 which passes through the bead-like part of said body and which has the same eccentricity as the opening 10 through the steel plug 7 and the Teflon disc 8, and the steel disc or plate 11 is provided with an opening having a shape corresponding to the configuration of the beadlike part of the steel body. The upper surface of the steel disc is spaced slightly from the main part of the steel body, so as to permit possible relative movement thereof caused by thermal expansion during the hardening or curing sequence. In the upper end of the opening 19, the steel body has a conical seat 20 for co-action with the lower end of a plunger 21, this lower end having a complementary conical shape. The aforesaid lower end is also provided with a peg 22 which fits into the cylindrical opening 19 and which when inserted into said opening extends to the under surface of the steel disc in abutment with the Teflon disc. In the Figures the openings 10 and 19 are shown in register with one another. When rotating the assembly comprising the steel disc 11, the brass body 12, and the sleeves 13 and 14, the opening 19 is moved relative to the opening 10, and upon rotating the assembly through a given angle of rotation, the steel disc or plate 11 will cover the opening 10. In this regard, it shall be easy to identify at least the position in which the openings 10 and 19 are in register with one another, e.g. by providing a terminal position for movement of the guide shoulder in the guide groove. The aforementioned tubular body 16 is attached sealingly to the upper end of the sleeve 14,by means of concentric lock nuts 23, a lock ring 24 which engages a groove in the tubular body, and a sealing ring 25.The tubular body is also provided with two axial openings 26 and 27, of which one, 26, is throughpassing and forms the inlet passage through which casting material is introduced into the mould cavity, and the other, 27, forms a bushing or leadthrough for the plunger 21, which is sealed against the wall of the bushing by means of an O-ring 28. The upper portion of the tubular body 16 presents a widened part 29 which is provided on the side of the bushing 27 with a bore 30 which partially overlaps the uppermost part of said bushing. The diameter of the bore is substantially larger than the diameter of the bushing or leadthrough 27, and is intended to accommodate a piston 31 for axial displacement therein. The piston has an upwardly open slot 32 in which a camming plate in the form of one end 33 of a lever arm is pivotally mounted on a pivot pin 34. The lower end of the piston 31 is attached to the upper end of the plunger 21, e.g. through a hook joint. A lever arm 35 extends laterally through an aperture formed in the widened part 29 of the tubular body 16, and the camming lever end 33 of the lever arm bears against a setting screw screwed into the uppermost part of the bore. When the lever arm is moved upwards from the horizontal position in Figure 1 to the vertical position in Figure 2, the piston 31, and therewith also the plunger 21, are forced downards to bring the bottom end of the plunger into abutment with the conical seat 20 of the steel body 12, lever arm movement from this position having the opposite effect. The die-casting gate valve operates in the following manner. Subsequent to filling the die with casting material through the inlet passage 26, the space formed by the sleeve 14, and the inlet opening 10, the lever arm 35 is moved upwardly, so as to swing the camming plate 33 to the position shown in Figure 2, therewith bringing the plunger 21 into sealing abutment with the seat 20. During this movement, the peg 22 forces casting material present in the opening 19 into the inlet opening 10 and then blocks the opening 19 in the steel disc. The mutually connected sleeves 13,14, and therewith the steel disc 11 and the steel body 12, are then rotated through 1800, therewith bringing the steel disc or plate 11 to a position in which it covers the inlet opening 10 through the steel plug 7 and the Teflon disc or plate 8. The casting material is then allowed to harden in the die, together with the sprue, which merely comprises a small or shallow stalk of some ten millimetres in length and which extends through the steel plug and the Teflon disc up to the steel disc or plate. This sprue is ground-off subsequent to dismantling the die. It will be seen that the invention provides an economically favourable solution, which also simplifies the manual work entailed in filling the die. The described and illustrated embodiment is not limitative of the invention, since several modifications are possible within the scope thereof. For example, the manner in which the rotatable valve components are attached may be varied, as may also the materials chosen for this manufacture. The lever mechanism may also have a form different to that illustrated and described. Consequently, the scope of the invention is solely restricted by the statements made in the following claims.

Claims: CLAIMS 1. A gate valve for a die or mould in which an article is to be cast under heat and pressure, characterized by a rotatable steel disc or plate (11) having an opening (19) which is positioned eccentrically in relation to the axis of rotation (A-A) and which in a first position of rotation is in register with the casting material inlet opening (10) to the die cavity and which in a second position of rotation lies to one side of ardoutside said inlet opening, such that the steel disc or plate (11) covers the die-cavity inlet opening (10) in said second position of rotation. 2. A valve according to Claim 1, characterized by an axially movable plunger (21) which in a first position exposes the opening (19) in the steel disc for the passage of casting material therethrough and which in a second position sealingly closes said opening (19), said plunger being rotatable together with the steel disc (11) and being moved to its second position when the steel disc (11) is rotated from its first to its second position. 3. A valve according to Claim 1, characterized in that the die-cavity inlet opening (10) is formed in a steel plug (7) and a Teflon disc or plate (8) which are arranged sequentially to one another and non-rotatably attached to a sleeve-like element (2) which extends into the die-cavity wall (1) to a level flush with the inner surface thereof and which is attached to the wall of a well (4) arranged in the die; and in that the casting material inlet opening (10) diverges towards the die cavity. 4. A valve according to Claim 2, characterized in that the steel disc (11) is firmly connected on the side thereof remote from the die cavity with an outwardly projecting part of a disc-like or plate-like metal body (12), this outwardly projecting part surrounding an opening (19) coinciding with the opening of the steel disc; and in that the metal body includes on the side thereof remote from the steel disc a conical seat (20) which is formed around the opening (19) in the metal body and receives the end of the plunger (21). 5. A valve according to Claim 4, characterized in that the steel disc or plate (11) and the metal body (12) are firmly connected to the ends of sleeves (13,14) arranged concentrically in the sleeve-like element (2), said sleeves (13,14) being connected to one another and journalled for rotation, but held against axial movement, in the end of the sleeve-like element remote from the sleeve-like element (2). 6. A valve according to Claim 5, characterized in that the inner sleeve (14) connected to the metal body (12) extends beyond the sleeve-like element (2) and in that the end of said body has provided in the end thereof remote from the die cavity an attachment for a tubular body (16) which incorporates two axial openings (26,27), of which the one opening, (26), is throughpassing and constitutes an inlet passage for the material to be cast, and the other, (27), forms a bushing for the plunger (21), which is sealingly guided in the bushing. 7. A valve according to Claim 6, characterized by a lever arm mechanism for effecting axial movement of the plunger (21).

Inventors: ERIKSSON, ROLF
Applicants: SHIRES LIMITED
Application year: 1986
Main classification: B29C31
IPC codes: B29C45, B29C31, B29C39