JPH0439492Y2 - - Google Patents

Description

[Detailed description of the invention] [Technical field] The present invention relates to a ball valve made of a plastic such as polyethylene resin, polyvinylidene fluoride resin, or polypropylene resin, which has poor adhesive properties. The present invention relates to a plastic ball valve in which a body cap is fused and fitted with a special structure to form a valve body, and a seat having a special structure is mounted within the body.

INDUSTRIAL APPLICATION This invention is utilized for the ball valve which is connected to the transportation piping of liquid, gas, powder, etc., and is widely used industrially.

[Conventional technology]

Conventionally, ball valves made of polyethylene resin, polyvinylidene fluoride resin, or polypropylene resin have had problems such as strength or sealing properties, the lack of an optimal adhesive, and difficulty in welding. Therefore, the main portion of the valve body and the body cap are generally fitted together by heat fusion.

For example, Japanese Patent Laid-Open No. 52-37230 discloses a ball valve having a structure in which end portions (body caps) are butt-fused to a main body portion from both sides. In this type of ball valve, since the ends are fused to the main body from both sides, it is difficult to center the ball, and it also requires skill to maintain the straightness of both ends. Furthermore, since the welding area is small, there is a problem in the strength of the welding.Furthermore, since the valve has a large number of parts, it takes time to assemble it, resulting in poor productivity.
Furthermore, British Patent No. 1233525 discloses a ball valve in which a body cap is fitted into the main body part, and only the outer end periphery of the part where the two are in contact (part A in Figure 1) is fused. . Even with these ball valves, centering the ball and body cap and adjusting the surface pressure between the ball and seat are difficult, and because there are few fused parts, there are problems in terms of sealing performance and pressure resistance against fluid pressure. have. Furthermore, in this structure, if all the contact parts of the main body part and the body cap are fused together, the bead that is generated when the body cap is inserted will protrude into the inside of the main body part (valve chamber) and come into contact with the ball or This may cause problems such as fusion. In addition, the sheet that comes into contact with the ball and maintains sealing properties is generally made of rubber elastic material or synthetic resin elastic material, but when the valve is opened and closed by the rotation of the ball, the sheet This tends to cause elastic deformation, which may impair the adhesion with the ball or cause it to jump out into the flow path. If such deformation or protrusion occurs, it is impossible to replace the seat if the valve body is formed by fusion bonding, so the valve body must be replaced, which is uneconomical.

[Purpose of invention]

The present invention was devised to solve the problems of the prior art as described above, and its purpose is to maintain a constant degree of insertion of the body cap attached to the main body part into the main body part, and to It prevents the bead from protruding into the valve chamber when welding the fitting, makes centering of the ball and body cap easy, and prevents elastic deformation of the seat when opening and closing the valve, providing stable sealing performance and welding strength. Our objective is to provide plastic ball valves.

[Structure of the idea]

The present invention has been made to achieve the above object, and is a plastic ball valve whose valve body is composed of a main body portion and a body cap that is fitted and fixed to the main body portion.
An annular notch and a peripheral side surface perpendicular to the axis of the body cap are formed at an end of the body cap receiving side of the body cap, and the body cap is fitted into the body cap. A flange portion, an annular stopper portion having a smaller outer diameter following the flange portion, and a seat holding portion protruding toward the main body portion following the flange portion are formed at the side end portions, and the seat holding portion on the body cap side is connected to the main body portion. Inserted into the main body part and inscribed on the inner circumferential surface thereof, the annular notch on the main body side has a circumferential side parallel to the axis, a subsequent circumferential side perpendicular to the axis, and the body cap side. A circumferential side surface parallel to the axis of the annular stopper section and a circumferential side surface perpendicular to the axis line of the collar section are respectively heated and welded, and the annular cutout section on the main body side and the annular shape of the annular stopper section on the body cap side are heated and welded. An annular groove for a bead is formed between the seat and the notch, and the seat attached to the main body portion and the body cap has an annular rib integrally formed with a semicircular cross section on its back peripheral surface; It is also characterized by having a structure in which an annular reinforcing metal fitting is embedded inside.

〔Example〕

Hereinafter, the present invention will be specifically explained based on the drawings of the embodiments thereof, but it goes without saying that the present invention is not limited to the present embodiments.

FIG. 2 shows an embodiment of the present invention. In the figure, 1 is a main body part (hereinafter abbreviated as main body part) of a valve body made of, for example, polyethylene resin, and a flow path 7 is provided in the center of the valve body.
It also has a valve chamber 8 in the center that rotatably holds a ball 9. An annular groove 11 with a rectangular cross section that is perpendicular to the axis of the flow path 7 and faces the ball 9, into which the seat 10 is fitted and held.
is provided. An annular oil groove 1 is provided on the outer peripheral side wall surface of the groove 11 to be filled with a sealing material such as grease.
1a is further provided. Further, an annular cutout 6 is provided at the end of the main body 1 on the side that receives the body cap 2.

2 is a body cap that is fitted to the main body portion 1 by fusion bonding. It has a flow path 7 in its center, and its outer periphery includes a flange 3 having an outer diameter slightly smaller than the outer diameter of the main body 1, and an annular stopper 4 continuous with the flange 3 having a smaller outer diameter. have. The stopper portion is provided with an annular notch 4b, and when integrated with the main body 1, both the notches 6,
An annular bead groove 15 is formed between 4b. The inner end of the body cap 2 is further reduced in diameter than the notch 4b to form a seat holding portion 16 that projects inward and is inscribed in the inner peripheral surface of the main body portion 1. An annular groove 11' having a rectangular cross section is provided on the inner circumferential surface of the seat holding part 16, and the seat 10' facing the ball 9 is fitted into and held therein. The surface pressure of the sheet 10' is kept constant. An annular oil groove 11'a for filling a sealing material such as grease is further provided on the outer peripheral side wall surface of the groove 11'. The main body part 1 and the body cap 2 have a circumferential surface 3a perpendicular to the flow path axis line of the flange part 3 on the body cap 2 side, a circumferential surface 4a of the annular stopper part 4 parallel to the axis line, and a circumferential surface 4a on the main body part 1 side perpendicular to the axis line. After simultaneously heating and melting the perpendicular circumferential side 5 and the circumferential side 6a parallel to the axis of the annular notch 6 following it, the corresponding circumferential sides 3a and 5 and 4a and 6a are fused, respectively. It is fitted by That is, by performing butt fusion and socket fusion at the same time, the bonding area between the main body portion 1 and the body cap 2 is increased, and the fusion strength is increased.

By providing the annular notch 6 in the main body part 1 and providing the annular stopper part 4 that fits into the annular stopper part 4 in the body cap 2, the circumferential surfaces 5 and 3a of the two come into contact with each other, and the degree of insertion of the body cap 2 into the main part 1 is reduced. Because it is constant, there is no trouble during assembly, and by increasing processing accuracy, the ball 9 and seat 1
The surface pressure 1' can also be kept constant. Furthermore, since the bead formed when inserting the body cap 2 into the main body part 1 is contained in the annular bead groove 15 formed between the annular notch part 6 and the notch part 4b of the annular stopper part 4, the main part 1
There is no possibility of contact or fusion with the protruding ball 9 inside the ball. Further, since the seat holding portion 16 protruding toward the main body portion 1 is inscribed in the inner peripheral surface of the main body portion 1 during assembly, centering of the ball 9 and the body cap 2 is facilitated.

Incidentally, the main body portion 1 and the body cap 2 are fused together by, for example, the following method. A heating element with metal jigs set on both sides corresponding to the circumferential sides to be fused is preheated to a temperature higher than the softening point of the plastic. Eventually, the jig is also heated at the same time. Next, the peripheral surfaces of the main body part 1 and the body cap 2 to be fused are simultaneously set in the corresponding jig, and after melting the peripheral surfaces appropriately, both are removed from the jig and immediately fitted. They are integrated by joining and fusing. In Figure 2, the fused surface is not actually shown as a solid line, but to make the structure easier to understand,
It is shown by a solid line.

Reference numeral 9 denotes a ball that is rotatably attached to the valve chamber 8 of the main body 1 and has a flow path 7 in the center. The ball 9 is fitted with the spindle 13, and the spindle 13
Turn the fluid flow on and off by opening and closing the flow path by turning the handle (not shown) 90 degrees left and right.
Turn off. The spindle 13 is fitted with a cap 14 which is pressably fitted into the rising portion 12 of the main body.

Sheets 10 and 10' are in contact with the balls and maintain sealing properties by maintaining a constant surface pressure. Sheet 10, 10' (represented by 10 below)
is made of rubber, Teflon, or other material, and the inner peripheral side of the surface that contacts the ball 9 is tapered to reduce the contact area with the ball 9 and increase the sealing surface pressure. Referring to FIG. 3, an annular reinforcing metal fitting 10a, which is the first feature of the sheet 10, is embedded inside the sheet 10. This serves to prevent the seat 10 from protruding from the annular groove 11 due to elastic deformation when the valve is opened and closed by the rotation of the ball 9. In addition, on the back circumferential surface of the seat 10, there are integrally formed
Several (three in the drawings) annular ribs 10b each having a semicircular cross section are provided. When fluid pressure is applied to the seat 10 via the ball 9, the ribs concentrate the pressure, and use it as a repulsive force to push back the seat 10, so that the ball 9 and the seat It functions to maintain a suitable surface pressure with respect to 10. Needless to say, it also functions to maintain sufficient sealing performance with the wall surface of the annular groove 11.

In another embodiment, as shown in FIG. 4, the side of the seat 10 facing the ball 9 is coated with a fluororesin 10c such as Teflon (registered trademark) in order to reduce the rotational torque of the spindle 13. are also preferred. An annular oil groove 11 provided on the outer peripheral side wall surface of the annular grooves 11, 11' (hereinafter referred to as 11) for attaching the seat.
A is filled with a sealing material such as grease.
For example, the grease filled in the oil groove 11a is
When the ball valve is used for a long period of time, the oil leaks out from the oil groove 11 and flows out to the surface of the seat 10 that comes into contact with the ball 9, thereby further improving the sealing performance between the seat 10 and the ball 9.

Although the handle is not shown in Figure 2, this is because the structure allows for different uses.When using the ball valve on the ground,
It can be used by removing the cap 14 from the spindle 13 and setting the handle on the spindle 13.
If the cap is to be buried in the ground, a cap 14 is fitted to the spindle 13, and a long handle is further fitted to the cap 14, as shown in the figure.

[Effect of idea]

As explained above, the present invention provides an annular notch in the main part of the valve body, and a corresponding annular stopper part in the body cap, allowing both to be strongly fused together by a combination of butt welding and socket welding. Even if they are fitted together by fusion bonding, it is easy to center the ball and body cap, and the degree of insertion of the body cap into the main body part is constant, making it possible to maintain a constant surface pressure between the ball and the seat. Furthermore, by using a specially structured seat and a sealing material such as grease, the ball valve can provide stable sealing over a long period of time. Furthermore, the linearity of the body cap can be easily obtained, and there is no problem in the fusing process since the beads do not enter into the main body. As a result of the above-mentioned effects, one of the effects is that assembly is easier than with conventional types and productivity is improved.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view of a conventional type plastic ball valve, Fig. 2 is a longitudinal sectional view of a plastic ball valve according to an embodiment of the present invention, and Fig. 3 is an enlarged sectional view of the seat in Fig. 2. , FIG. 4 is an enlarged sectional view showing another embodiment of the sheet. A... Fusion part, 1... Main body part, 2... Body cap, 3... Flange part, 4... Annular stopper part, 6... Annular notch part, 7... Channel, 9... Ball, 10, 10'... Sheet, 10a, 10a'...
...Annular reinforcing metal fitting, 10b, 10b'...Annular rib,
10c, 10c'...resin coating, 11,1
1'... annular groove, 11a, 11a'... annular oil groove,
15... Annular groove for bead, 16... Sheet holding part.

Claims (1)

[Claims for Utility Model Registration] 1. A plastic ball valve whose valve body is composed of a main body part and a body cap fitted and fixed to the main body part, wherein an end of the main body part on the side that receives the body cap is forms an annular notch and a circumferential side surface perpendicular to the axis of the main body portion, and a flange portion and a flange portion are formed at the end of the body cap on the side to be fitted into the main body portion. A small-diameter annular stopper portion and a subsequent seat holding portion protruding toward the main body portion are formed, and the seat holding portion on the body cap side is inserted into the main body portion and inscribed in the inner circumferential surface thereof. Also, a circumferential side surface parallel to the axis of the annular notch on the main body side and a subsequent circumferential side perpendicular to the axis, a circumferential side parallel to the axis of the annular stopper section on the body cap side, and the flange. and a circumferential side surface perpendicular to the axis of the body cap, respectively, to form an annular groove for a bead between the annular notch on the main body side and the annular notch of the annular stopper on the body cap side, Furthermore, the seat attached to the main body portion and the body cap has an integrally molded annular rib having a semicircular cross section on its back peripheral surface, and has an annular reinforcing metal fitting embedded therein. A plastic ball valve characterized by: 2. The plastic ball valve according to claim 1, which is characterized in that a sheet coated with fluororesin is attached to the side surface facing the ball. 3. The plastic ball valve according to claim 1 or 2 of the utility model registration, characterized in that an annular oil groove is provided on the outer peripheral side wall of the annular groove for attaching a seat in the main body portion and the body cap.