WAFER BALL VALVE OF SYNTHETIC MATERIAL WITH BUILT-IN CORE

Abstract: Wafer type ball valve (9) having a flat discoid body (10) consisting of two component parts, a crown-shaped supporting structure (11) of molded plastic material and a central metal core (12) in which to house the ball (13), placed in the die at the beginning of the molding process so that, when the process terminates, it will be stably incorporated within said structure (11).

Description: Wafer ball valve of synthetic material with built-in core The presently known wafer type ball valves, of flat struc¬ tures, have a substantially solid metal body to support the closing part worked by a handle through a pin that connects the ball with the outside. Said metal body is generally heavy and bulky this being necessary to make the valve strong and functionally re¬ liable. But the valve must also withstand aggressive agents both from its environment and from the products used in the equipment on which it works and this involves problems of expense since the metal must necessarily be of high quali¬ ty and therefore costly. The weight of the valve naturally creates further prob¬ lems of packing and transport, two more items that con¬ tribute to raising its cost. The above invention solves these difficulties and offers other considerable advantages as will be described. Subject of the invention is a wafer type ball valve having a flat disk-shaped body and a device to limit the stroke made by an operating handle for the valve's open and close positions . Said body comprises two parts, a molded crown-shaped sup¬ porting structure and a central metal core in which the ball is housed. The structure and core are stably associated by placing th core inside the die before molding so that when the proces terminates the core is incorporated in said structure. In one preferred type of execution the structure is of pla stic material and the die is therefore of a kind suitable for molding plastic. Said die consists of two matching halves. The metal core is supported and centered in one of said halves by means of a transversal pin which lies axially in relation to the half die and to the core. The limit stop device is a metal peg fixed to the top of the valve body and projecting inside a fork, mounted on the shaft of the ball, to which the operating handle is fixed, placed between said top of the valve body and said operating handle. One of the die halves contains a slot for said peg, fitted with a permanent magnet. Placed in its slot before molding, said peg projects in a portion of the die shaped so that a suitable hold is made for it when the material is put in. When molding is finished, said peg will be stably fixed into the structure of the valve and will project close to the shaft of the operating handle providing a limit to mark the ends of the open and closed positions of the valve. Alternatively said peg forms part of the crowi-shaped supporting structure obtained by molding, if a suitable impression is provided inside the die. The parts most exposed to mechanical stress and chemical action, such as the core and the ball, are made of mater- ials generally employed for such types of valves, especial ly metals. The crown-shaped supporting structure may be made of ferrous or non-ferrous metals, plastic, thermo¬ plastic, thermohardening plastic or other suitable materials The purpose of this is to reduce manufacturing costs and lessen the weight of the valve without adversely affecting its strength and ability to withstand mechanical and cor- rosive wear . The outer cylindrical surface of the core is processed to ensure maximum adhesion between said core and the crown- -shaped supporting structure made by molding round the cor Thickness of the substantially discoid metal core is great than that of the structure created by the molding process, said structure too being virtually discoid. The position of said core is practically symmetrical in re lation to said structure so that, when the valve is instal the structure's lateral faces, projecting on either side, ensure their direct contact with the flanges on the pipes thus making a strong and reliable connection. The advantages of the invention will be clearly understood All parts exposed to mechanical and chemical action are made of metals or, in any case, of materials normally used for-the various functions, metals such as steel, stainless steel, brass, aluminium, bronze, cast iron or even others. But as the structural parts connecting the operating parts and the valve itself, comprising core and ball, consist of a crown of synthetic material made lighter by the presence of voids, while the valve provides maximum strength and precision, its cost is considerably less than that of the usual valves both on account of the materials used and of the process by which it is made. Being so much lighter in weight this valve is also more convenient to pack and transport, as well as to handle and instal1. Charac eristics and purposes of the invention will be made still clearer by the following example of its execution illustrated by diagrammatically drawn figures. Fig. 1 The valve subject of this invention, front view. Fig. 2 A transversal ' section of the valve. Fig. 3 The valve seen from above. Fig. 4 The valve's structure of plastic material, front view. Fig. 5 A transversal section of the same structure. Fig. 6 A transversal section of the valve core. Fig. 7 A front view of the valve coτe. Fig. 8 The valve's body after molding, front view. Fig. 9 A transversal section of the valve's body. Fig.10 First half of the die for'molding the valve's body, front view. Fig.11 The above seen from the side. Fig.12 The second half of the die, seen from the side. Fig.13 Front view of the second half of the die. The valve 9 comprises a body 10 consisting of a crown-shape structure 11 of synthetic material which tightly encloses a metal core 12. Said core 12 is associated to the structure 11, when the latter is molded, by its being placed in the die before injection of the material. The central ball 13 is connected to the handle 14 by a pin 15 with threading 16 and nuts 17-18. Said handle is fixed to the fork 21 whose ends 19,20 at 90° form two stops to limit rotation of the ball 13 and mark the open and closed positions of the valve body 10. The limit stops consist of the metal peg 25 sunk into the volume 26 of the structure and projecting from the top 27 of said structure. Said structure 11 virtually consists of an annular lami- nar body 30 that connects the substantially cylindrical coaxial faces 31, 32 and four tubular bodies 33 parallel to the axis, at an equal angular distance, for passage of the bolts or pins connecting them to the flanges on the piping on which said valve 9 is mounted. The core 12 consists of a cylindrical body having a la¬ teral face 41 in which there is an axial hole 42, and an open face 43 to which, after introduction of the ball 13, the lid 48 with a hole 49 is screwed on by the thread 44. Packing 47 for the ball 13 is placed at the two faces 41, 43 in the chamber created inside the core 12. The die for molding the structure 11 consists of two halves 50, 51. The first half 50 has in it the impression 52 for one face of the valve structure I I and devices for expul¬ sion of the valve body 10, the pneumatic cylinder 53 and piston.'. 54 guided by the bushing 55. The second half 51 of the die contains the impression 56 for the second face of the valve structure 11 and guide pegs 57 to slide in the holes 58 of the die's first half 50 Centrally in the impression 52 of the first die half 50 the is a pin 60 for suspending and centering the valve's metal core 12 inside the die. In the zone 59 of the die is a slot 61 containing a per¬ manent magnet for holding the metal peg 25 that limits rotation of the handle 14. Clearly, before . starting to mold the structure 11, the core 12, supported and held in a central position by the axial pin 60, is placed in the first half of the die 50. The peg 25, placed in the slot 61 (Fig. 10) fitted with the permanent magnet, thus occupies the most useful posi¬ tion in relation to the structure 11, as seen in Figs. 1 and 2. The die is then closed by putting together the two halves 50 and 51 guided by the pegs 57. Around the core 12 a chamber is thus created corresponding to the shape of the structure 11. The molding process then proceeds. The plastic material put into the die will produce the structure 11 that tightly and centrally enfolds the core 1 On opening the die the valve body 10, illustrated in Figs. 8 and 9, complete with structure 11, core 12 and limit sto peg 25, can be lifted out. The suitably processed surface 45' of said core 12 ensures its stable incorporation within said structure 11. Operational parts, especially the handle 14 seen in Figs. 1 and 2, can then be mounted to produce a valve 9 giving an excellent performance but being at the same time inex¬ pensive and light in weight.

Claims: C l a ims 1. Wafer type ball valve (9) having a flat discoid body ( 10) and limit stop device (21,25) for an operating handle ( 14) in the two open and closed positions, characterized in that said body ( 10) is made of two com¬ ponent parts, a crown-shaped supporting structure ( 11) pro¬ duced by molding, and a central metal core ( 12) to house the ball ( 13), said structure ( 11) and said core ( 12) being stably associated in that the core ( 12) is placed inside the die(50, 51) at the start of molding so that when this process terminates said core is incorporated inside said structure ( 11). 2. Ball valve (9) as in claim 1, characterized in that the die (50,51) used for molding is made of two matching halves (50, 51), the metal core ( 12) being supported and centered in one (50) of said die halves by means of a transversal pin (60) lying axially both to the die half (50) and to the core ( \2 ) . 3. Ball valve (9) as in claim 1, characterized in that the limit stop device is a metal peg (25) fixed to the top (27) of the body ( 10) of the valve (9) and projecting inside a fork (21), mounted on the shaft (15) which carries the operating handle ( 14), placed betwee said top (27) of the body ( 10) of the valve (9) and said operating handle ( 14); there being in one (50) of the half dies (50, 51) a slot (61) for said peg (25), said slot con¬ taining a permanent magnet, so that when said peg (25) is put in its slot (61) before the die (50, 51) is closed, at the end of molding it will be firmly associated within the structure ( 11) of the valve (9) and project close to the shaft ( 15) of the operating handle ( 14) to form- the limit s to movement of said handle ( 14) in its end closing and open ing positions . 4. Ball valve (9) as in claim 1, characterized in that the limit stop device is a peg (25) fixed to the top (27) of the body ( 10) of the valve (9) and projecting inside a fork (21) fixed to the shaft ( 15) onto which is mounted the operating handle ( 14), placed between said top (27) of the body ( 10) of the valve (9) and said operating handle ( 14), said peg (25) being made all in one piece with the supporting structure ( 11) by means of the molding process. 5. Ball valve (9) as in claim 1, characterized in that all the parts subjected to heaviest mechanical and chemical wear, such as the core ( 12) and the ball ( 13), are made of the materials generally used for suc types of valves, especially metal materials. 6. Ball valve (9) as in claim 1, characterized in that the supporting, structure ( 11) is made of plastic material. 7. Ball valve (9) as in claim 1, characterized in that the supporting structure ( 11) is made of different materials, as the case may be, such as ferrous metal, non-ferrous metal, thermoplastic, thermohardening plastic and any other suitable kind. 8. Ball valve (9) as in claim 1, characterized in that the external cylindrical surface (45) of the core ( 12) is suitably processed to ensure maximum adhesion between said core ( 12) and the supporting struc¬ ture ( 11). 9. Ball valve (9) as in claim 1, characterized in that the thickness of the substan ially discoid metal core (12) is greater than the thickness of the supporting structure ( 11), this too being substantially discoid, said core ( 12) being placed in a practically sym¬ metrical position in relation to said structure ( 11) so that the lateral faces of said core ( 12) ,projecting out on either side of the structure ( 11), ensure direct contact between said lateral faces and the flange joining the.valve to the main pipe thus making a joint of maximum reliability and strength. 10. Ball valve (9) as in claim 1, characterized in that the supporting structure ( 11) virtual ly consists of a central laminar element (30) that joins the two coaxial, subs antially cylindrical outer (30) and inner (31) faces extending perpendicually on either side of said laminar element (30) and a number of tubular elements (33) parallel to the axis, to allow passage of pins, bolts, means of connection generally with the flanges on the main pipes, thickness of said elements (SO, 33) being the minimu compatible with the material used, the purpose of this being to obtain a strong structure obtainable by a quick molding process to produce a valve of minimum weight and cost.

Inventors: NEGRI GUIDO, NEGRI, GUIDO
Applicants: NEGRI FLLI SRL, NEGRI GUIDO, NEGRI FRATELLI S.R.L., NEGRI, GUIDO
Application year: 1993
Main classification: F16K5
IPC codes: F16K5, F16K27