JPS636336B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a synthetic resin ball valve.

As a method of manufacturing this type of ball valve by injection molding, a previously prepared valve body, spindle, and seal ring are placed in a mold having an internal space having the same shape as the external shape of the ball valve, and There is a method of manufacturing by defining a cavity in the space and inserting a pair of slide cores that butt inside the valve body, and then injecting synthetic resin into a mold and solidifying it. The resin-covered seal ring receives extremely high resin pressure, causing plastic deformation.
There is a problem that the desired sealing effect cannot be expected, and in reality, there are dimensional errors in the ball plug and seal ring due to manufacturing, so the slide core must be controlled according to the dimensional errors. Therefore, an expensive molding machine with a hydraulic control device is required.Furthermore, in order to prevent the above-mentioned plastic deformation, preloading the seal ring to balance the resin pressure during molding requires a complicated control device. In addition to requiring the use of a very expensive molding machine, the required injection pressure becomes high, resulting in a problem in that the quality performance of the ball valve deteriorates.

The present invention has been made in view of the above-mentioned conventional problems, and includes an annular escape groove that is provided on the sliding surface side of the seal ring and an annular relief groove that is in close contact with the back side of the groove so that the seal ring can be pressed against the ball stopper. By installing a seal retainer on the slide core and creating a relief for the inner diameter side of the seal ring, the valve body has a more stable and high sealing function than conventional valves, and the quality of the valve body is also excellent. It is an object of the present invention to provide a method for manufacturing a ball valve that allows the valve to be manufactured using an inexpensive molding material.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view of a ball valve A manufactured according to the present invention. In the figure, 1 is the valve body,
It houses the ball stopper 2 and has connection ports 4, 4 on the left and right that communicate with the valve holes 3, 3. 2a is a plug hole of the ball plug 2, and 5 is a spindle.

6, 6 is a seal ring, which has an inner diameter smaller than the hole diameter of the valve holes 3, 3 and larger than the plug hole 2a, and an outer diameter larger than the hole diameter, and a sliding ring having a curved surface along the spherical surface of the ball plug 2. Place the surface 6a on the ball stopper 2,
The ball plug 2 of the valve body 1 is concentric with the plug hole 2a.
The valve hole 3 is located between one side of the valve hole 3 and the ball plug 2, and between the other side of the valve hole 3 and the ball plug 2, respectively. The seal ring 6 has a circumferential relief groove 7 in a portion of its sliding surface 6a that approximately corresponds to the diameter of the valve hole 3, and the outer side of the seal ring 6, bordering on the relief groove 7, receives resin pressure during molding. The plastically deformed portion 6A has a non-plastically deformed portion 6B whose inner side is substantially released from the resin pressure during molding and has a stable and high sealing function.

Next, a method for manufacturing this bulb A will be explained with reference to FIG. 2.

In Fig. 2, B is the mold of the injection molding machine, 11
is a fixed side plate, 12 is a fixed side template, 13 is a movable side plate, 14 is a movable side template, 15, 15 is a slide core, 16, 16 is an inclined pin, 17 is an ejecting pin,
18 is a sprue, and slide core 15,1
5 is controlled by inclined pins 16, 16.

When manufacturing the ball valve A, in addition to the core bodies 15a of the slide cores 15, 15, a ball plug 2 with a spindle 5 prepared in advance and A cavity 20 having the shape of the valve body 1 is defined by inserting the seal rings 6, 6 at the center. Slide core 1
The core bodies 15a of Nos. 5 and 15 have the same outer shape as the left half and right half of the internal flow path of the ball valve A, respectively, and the ball plugs 2 of each stepped portion 15b forming the valve holes 3, 3.
As shown in an enlarged view in FIG. 3, the outer periphery of the side step end face is provided with a ring-shaped seal retainer 15c that protrudes in the axial direction, and in the illustrated mold clamping state, each seal retainer 15
c are in close contact with the back surfaces 6b of the seal rings 6, 6 on the core bodies 15a, 15a, respectively, and create an escape space α between them and the respective back surfaces 6b inside the seal retainers 15c on the end faces of the stepped portions. ing.

When resin is injected into the cavity 20,
A compressive force due to resin pressure acts on the portion 6A of the seal rings 6, 6 that protrudes into the cavity 20, causing plastic deformation, but a part of the compressive force is transferred to the seal rings 6, 6.
It is absorbed by the relief groove 7 on the sliding surface 6a side of 6, and the relief groove 7 and the seal retainer 15c
The part 6B inside the narrow part 6C between the gaps deforms to the side of the relief space α and absorbs the compressive force, so there is virtually no fear of plastic deformation and the desired sealing function is maintained even after the valve body 1 is molded. hold.

FIG. 4 shows another embodiment of the present invention, in which the contact surface between the sliding surface 6a of the portion 6B of the seal ring 6 and the ball plug 2 is parallel to the rotation axis of the ball plug 2. The ball stopper 2 is chamfered to enhance the sealing effect.

Incidentally, as shown in FIG. 5, the sealing member 8 of the spindle 5 portion may also be fitted onto the spindle 5 in advance to perform the molding of each of the above embodiments. 9 is a seal retainer, which is fitted into the spindle 5.

As described above, according to the present invention, an relief groove is provided on the sliding surface side of the seal ring to absorb a part of the resin pressure during molding, and a seal retainer that protrudes in the axial direction is provided on the slide core, so that the inner diameter of the seal groove is By forming an escape space for the side, the inner diameter side of the seal ring is released from the resin pressure during molding, so that the desired sealing function can be achieved. Furthermore, even if there is a manufacturing error in the dimensions of the seal ring or ball plug, the seal retainer can absorb this manufacturing error as long as the manufacturing error is not extreme, so the slide core can be adjusted according to the manufacturing error. There is no need to control the position, and unlike the method of applying extra pressure to the seal ring to balance the resin pressure during molding, there is no need to control the molding pressure, so an inexpensive injection molding machine with a simple structure can be used. It is possible to manufacture ball valves with superior performance and quality compared to conventional ones.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal cross-sectional view of a ball valve manufactured by carrying out the method for manufacturing a synthetic resin ball valve according to the present invention, and Fig. 2 is a longitudinal cross-sectional view of a molding die for explaining an embodiment of the present invention. , FIG. 3 is an enlarged sectional view of the main part of FIG. 2, and FIGS. 4 and 5 are sectional views of the main part for explaining other embodiments of the present invention. 1... Valve body, 2... Ball stopper, 2a... Bung hole, 3... Valve hole, 4... Connection port, 5... Spindle, 6... Seal ring, 6A, 6B... Part, 6a
...Sliding surface, 6b...Back surface, 7...Escape groove, 8...
... Seal member, 12, 14 ... Template, 15 ... Slide core, 15a ... Core body, 15b ... Step portion, 15c ... Seal retainer, 20 ... Cavity.

Claims (1)

[Claims] 1. A ball plug with a spindle, a seal ring, and the core bodies of a pair of slide cores prepared in advance are placed in the internal space created by the template of the molding die to define a cavity in the shape of the valve body, and resin is injected into the cavity. In the method of manufacturing a ball valve, the seal ring has a shape in which the sliding surface that comes into contact with the ball stopper has a circumferential relief groove, and the core body of the slide core has an annular seal retainer that protrudes in the axial direction. A method for manufacturing a synthetic resin ball valve, characterized in that the resin is injected while the seal retainer is brought into close contact with the back surface of the seal ring.