JP3128109B2 - Ball valve and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ball valve having an integral synthetic resin body used for piping of water, oil, gas and the like, and a method of manufacturing the same.

[0002]

2. Description of the Related Art A sectional view shown in FIG.
No. 888 and Japanese Utility Model Application Laid-Open No. 2-76980 show a conventional example of a ball valve having an integrated synthetic resin body. Reference numeral 22 denotes a body which is injection-molded integrally using the rotary member 21 as a part of the core, 23 denotes a handle, and 24 denotes a ball valve.

In this ball valve 24, the rotating member 21
Is rotated by approximately 90 degrees from the state shown in the figure, the seal is made by the contact between the outer surface of the ball portion 21b and the inner surface of the body 22 in contact with the ball portion 21b. In order to achieve this, it is necessary to ensure contact at the contact surface and at the same time a contact surface pressure slightly higher than the pressure of the fluid. The contact surface pressure is generally obtained by a differential pressure between the fluid on the upstream side and the fluid on the downstream side pushing the ball to the downstream side.

FIGS. 8 and 9 are partial cross-sectional views showing the shape of a joint portion between a ball and a stem of a floating ball type ball valve in which a ball is pushed downstream by a differential pressure between fluids on an upstream side and a downstream side to seal the ball. It is a figure, and in both figures, the balls 25 and 26 can be moved to the right or left of the figure with respect to the stem 27 or 28. For example, the right side of both figures is the upstream side. When the pressure difference between the upstream and downstream fluids is applied to the ball 25 or 26, the ball 2
5 or 26 moves to the left and the left seal 29 or 30
And press to seal.

In the ball valve 24 shown in FIG. 7, since the ball portion 21b is formed integrally with the stem portion 21a, the ball portion 21b is different from the case shown in FIGS. Due to the differential pressure between the acting upstream and downstream fluids, the fluid cannot move to the downstream side.
Since the contact surface pressure between the outer surface of b and the inner surface of the body 22 in contact therewith does not increase, the sealing performance is poor.

In order to solve the above-mentioned problem concerning the ball valve 24 shown in FIG. 7, Japanese Patent Publication No. 59-22109 discloses a state in which a ball portion 21b which becomes a core when the body 22 is injection-molded is shown in the drawing. After applying pressure from the right and left to elastically deform the body 22, the pressure is removed after the body 22 is formed, and the outer surface of the ball 21b and the inner surface of the body 22 in contact with it are restored by the restoring resilience of the ball 21b. A method is proposed in which the contact surface pressure between them is increased to improve the sealing performance.

In this method, only the contact surface pressure between the outer surface of either the downstream or upstream ball portion 21b required for sealing and the inner surface of the body 22 in contact therewith increases. Therefore, a large force is required to rotate the rotating member 21 because both are high. In addition, in order to cause the ball to undergo elastic deformation, it is necessary to make the core have a special structure or press it with a press. Further, the ball portion 21
Since the contact surface pressure between b and the body 22 is constantly acting, there is a problem that the plastic deformation of the body 22 easily occurs, the body 22 easily wears, and is not suitable for long-term use.

[0008]

The problem to be solved by the present invention is, as described above, a ball having a synthetic resin body which is integrally molded by using a ball and a stem as a part of a core. Since the valve uses the ball and stem as a part of the core, it is usually formed integrally, and the ball cannot be pressed against the body by the differential pressure between the fluids on the upstream and downstream sides. As a countermeasure and the method of compressing and deforming the ball part during molding of the body, it is necessary to make the core a special structure or press it with a press, the operation requires a large force, and the body is plastically deformed. The present invention is easy to wear and is not suitable for long-term use, and the present invention has been developed as a result of intensive research to solve these problems at once.

[0009]

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention is constituted as follows. In a ball valve having a synthetic resin body that is injection-molded integrally using a ball and a stem as a part of a core, the ball and the stem abut on a plane formed on a part of the spherical surface of the ball, The convex portion formed on the ball or the stem is inserted into the concave portion formed on the stem or the ball, so that the ball has no play in the rotation direction with respect to the stem, and there is play in the direction crossing the passage hole of the ball. Formed as follows.

In this case, the convex or concave portion of the ball has two flat surfaces perpendicular to the flow path hole, and the concave or convex portion of the stem has
The ball has two parallel surfaces which are in contact with each other without play, and when the ball and the stem have a convex portion and a concave portion which are joined to each other when the ball and the stem are joined to each other, the ball flows into the ball with respect to the stem. The cross section may be formed in a substantially square or substantially rectangular shape so as to have play in a direction perpendicular to the hole, and the stem may have a tapered outer peripheral surface whose diameter increases toward a contact surface with the ball. The resistance heating wire may be buried in the inner diameter of at least one of the pipe connection sockets.

In addition, a ball and a stem are temporarily connected to each other using bolts, and this is used as a part of a core to integrally form a body made of synthetic resin to manufacture a ball valve.

[0012]

Since the ball valve of the present invention is constructed as described above, the ball and the stem come into contact with each other on a plane formed on a part of the spherical surface of the ball, and the projection formed on the ball or the stem has the stem. Alternatively, the cross section is formed in a substantially square or substantially rectangular shape so that the ball is inserted into a recess formed in the ball and has no play in the rotational direction with respect to the stem and has play in the direction crossing the passage hole of the ball. Therefore, the differential pressure between the fluid on the upstream side and the fluid on the downstream side acts on the ball, and the ball is pressed against the downstream side of the body, thereby performing a reliable seal.

Further, the frictional resistance between the ball and the body is
Since the pressure difference is generated only at the downstream side when a fluid differential pressure is generated, the operating torque for opening and closing the valve by rotating the ball is small, and the body can be used for a long time without plastic deformation or wear. Suitable for.

When the convex and concave portions formed on the ball and the stem are joined, there is no play in the direction of the flow path hole of the ball, and the cross section is substantially square or so as to have play in the direction perpendicular to the flow hole. Forming a rectangular shape is easy if a dedicated processing tool is prepared, the dimensions and shape are accurate, and the intended operation of the present invention can be reliably obtained.

Further, when the stem is provided with a tapered outer peripheral surface which expands in diameter toward the contact surface portion with the ball, a tapered inner peripheral surface is also formed on the body side, so that the stem and the ball come into contact with each other. To prevent the stem from jumping out.

When a resistance heating wire is buried in the inside diameter of one or both of the pipe connecting sockets of the body of the ball valve, the synthetic resin tube is fused by energizing the resistance heating wire, thereby facilitating fusion. Can be plumbed.

Next, during injection molding of the body, the ball and the stem are temporarily and firmly joined to each other by using bolts to form a part of the core. Can be formed. After the body is formed, the bolt is removed.

[0018]

FIG. 1 is a longitudinal sectional view showing an embodiment of a ball valve according to the present invention, wherein 1 is a ball valve, 2 is a ball having a passage hole 2d, 3 is a stem for rotating the ball,
Reference numeral 4 denotes a body in which the ball 2 is built. The plane 3a of the stem 3 is in contact with the plane 2a formed on the spherical surface of the ball 2, and the projection 2b formed on the ball 2 is parallel to the cylinder.
The surface 2c is formed. The recess 3b formed in the stem 3 is a hole having a rectangular cross section. There is no play between the recess 3b and the two parallel surfaces, and the recess 3b and the projection 2b are formed.
In the direction perpendicular to the flow path hole 2d, that is, in the cross section shown in the drawing, the passage is formed so as to have the play shown in FIG.

FIG. 2 is a partial longitudinal sectional view showing another embodiment of the ball valve of the present invention. The ball 2 has a concave portion 2e having a rectangular cross section, and the stem 3 has two parallel surfaces parallel to a cylinder. There is no play between the concave portion 2e and the two parallel surfaces 3c, and the concave portion 2e and the convex portion 3c are formed.
In the direction intersecting the flow path hole 2d with d, that is, in the cross-section shown in the figure, it is formed so that there is play shown in the figure b.

FIG. 3 is a partial longitudinal sectional view showing still another embodiment of the ball valve of the present invention. The stem 3 has a tapered outer periphery which expands in diameter toward a plane 3a of a contact surface portion with the ball 2. It has a surface 3e. Except for this, it has the same shape as FIG. FIG. 4 is a partial longitudinal sectional view showing still another embodiment of the ball valve of the present invention.
Similarly, a tapered outer peripheral surface 3e is provided. Otherwise, it has the same shape as FIG.

FIG. 5 is a partial longitudinal sectional view showing still another embodiment of the ball valve according to the present invention, wherein at least one pipe connection socket portion 4a of the body 4 of the ball valve 1 is provided.
The resistance heating wire 5 is buried in the inner diameter portion 4b.

FIG. 6 is a longitudinal sectional view showing an embodiment of the method of manufacturing a ball valve according to the present invention. It becomes a child and is mounted in the outer dies 9 and 10. A body is formed by injecting a synthetic resin into a space 11 formed between the cores of the outer dies 9 and 10.

Next, the operation of the ball valve 1 of the present invention will be described based on the embodiment shown in FIGS. First,
The plane 2a and the plane 3a are in contact with the ball 2 and the stem 3, and the convex part 2b of the ball 2 is inserted into the concave part 3b of the stem 3 or the convex part 3d of the stem 3 is inserted into the concave part 2e of the ball 2. The ball 2 has no play in the rotation direction with respect to the stem 3 (since there is no play in the direction of the flow passage hole 2d of the ball 2, FIG.
(See FIG. 1A and FIG. 2B) in the direction perpendicular to the flow path hole 2d of the ball 2.
The differential pressure between the fluid on the upstream side and the fluid on the downstream side acts on the ball 2, and the ball 2 is pressed to the downstream side of the body 4 (to the right or left in FIGS. 1 to 4), and a reliable seal is performed.

Further, since the ball 2 receives frictional resistance with the body 4 only when a fluid pressure difference is generated, only the downstream side as described above, the ball 2 is rotated to open and close the valve 1. The operating torque is small, and the body 4 does not undergo plastic deformation or wear, and is suitable for long-term use.

Further, when the stem 3 is provided with a tapered outer peripheral surface 3e whose diameter increases toward a plane 3a in contact with the ball 2, the tapered inner peripheral surface 4a is also provided on the body 4 side (FIGS. 3 and 4). ) Is formed by injection molding, so that the plane 3a of the stem 3 and the plane 2a of the ball 2 are maintained in contact with each other to prevent the stem 3 from jumping out.

By energizing the resistance heating wire 5 embedded in the inner diameter part 4b of the socket part 4a for connecting at least one of the pipes of the body 4 of the ball valve 1, the synthetic resin pipe is fused and easily piped. can do.

Next, in the method of manufacturing a ball valve according to the present invention, as shown in FIG. 6, the ball 2 and the stem 3 are firmly temporarily connected with the bolt 6 to form a part of the core. ,
A stable and strong core can be formed, and a body of accurate dimensions and shape can be formed. After injection molding of the body, mandrel 7
After removing the outer molds 9 and 10 and the bolts 6, the bolts 6 are removed.

[0028]

The excellent effects of the ball valve of the present invention and the method of manufacturing the same are as follows. The sealing surface pressure between the ball and the body is obtained by the differential pressure between the fluid on the upstream side and the downstream side, so that the sealing performance is good, and this sealing surface pressure is not always acting, but is in a closed state. Since it occurs only on the downstream side of the body, a large force is not required for opening and closing operations, and plastic deformation and wear of the body hardly occur, which is suitable for long-term use. Further, the processing of the projections and depressions for connecting the body and the stem is easy, the dimensions and the shape are accurate, and the desired operation can be reliably obtained.

Next, according to the manufacturing method of the present invention, the ball and the stem are firmly connected to each other by using bolts to form a part of the core. The body can be formed, and it is not necessary to compress the ball to cause elastic deformation, and to use a special structure core or press for this purpose.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing one embodiment of a ball valve of the present invention.

FIG. 2 is a partial longitudinal sectional view showing another embodiment of the ball valve of the present invention.

FIG. 3 is a partial longitudinal sectional view showing still another embodiment of the ball valve of the present invention.

FIG. 4 is a partial longitudinal sectional view showing still another embodiment of the ball valve of the present invention.

FIG. 5 is a partial longitudinal sectional view showing still another embodiment of the ball valve of the present invention.

FIG. 6 is a longitudinal sectional view showing one embodiment of the method for manufacturing a ball valve of the present invention.

FIG. 7 is a longitudinal sectional view showing an example of a conventional ball valve.

FIG. 8 is a partial sectional view showing a general shape of a joint portion between a ball and a stem of a floating ball type ball valve.

FIG. 9 is a partial sectional view showing a general shape of a joint portion between a ball and a stem of a floating ball type ball valve.

[Explanation of symbols]

 Reference Signs List 1 ball valve 2 ball 2a flat surface 2b convex portion 2c parallel 2 surface 2d flow passage hole 2e concave portion 3 stem 3a flat surface 3b concave portion 3c parallel 2 surface 3d convex portion 3e tapered outer peripheral surface 4 body 4a socket portion 4b inner diameter portion 5 resistance heating wire 6 bolts a, b play

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-2-76980 (JP, A) JP-A-55-30506 (JP, A) JP-A-6-84073 (JP, U) JP-A-60- 56865 (JP, U) JP-B-59-22109 (JP, B2) JP-B 37-22370 (JP, Y1) JP-B-6-19888 (JP, Y2) Table 7-501127 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) F16K 5/06 F16K 27/06

Claims (5)

(57) [Claims] 1. A ball valve having a synthetic resin body integrally formed by injection molding in a space around a ball using a ball and a stem as a part of a core. surface contact with have your part, forming the protrusion by inserting the convex portion formed on the ball or stem in a recess formed in the stem or ball in a recess in the contact surface portion of the
By, no play in the rotational direction the ball relative to the stem, ball valve, characterized in that formed such that there is play in a direction intersecting the flow path hole of the ball. 2. The convex portion or concave portion of the ball has two flat surfaces perpendicular to the flow path hole, and the concave portion or convex portion of the stem has two parallel surfaces contacting the two parallel surfaces of the ball without play. Having a substantially square or cross section so that when the ball and the stem are joined to each other, the ball and the stem have play in a direction perpendicular to the flow path hole of the ball when the ball and the stem are joined. 2. The ball valve according to claim 1, wherein the ball valve is formed in a substantially rectangular shape. 3. The ball valve according to claim 1, wherein the stem has a tapered outer peripheral surface whose diameter increases toward a contact surface portion with the ball. 4. The ball valve according to claim 1, wherein a resistance heating wire is buried in an inner diameter portion of at least one pipe connection socket portion of the body. 5. A method of manufacturing a ball valve, comprising: temporarily connecting a ball and a stem using bolts; and using the bolt as a part of a core to integrally form a body made of synthetic resin.