JP2605751Y2 - Mold - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvement of a mold.

[0002]

2. Description of the Related Art When molding a molded article 21 shown in FIG.
Conventionally, a mold shown in FIG. 5 has been used.

The molded product 21 shown in FIG. 4 is specifically a plug tube gasket for sealing between a head cover of a cylinder and a plug tube, and has an annular rubber portion with a reinforcing ring 22 and a garter spring 23 embedded therein. 24
Is vulcanized to the shape shown in the figure.

The molding die shown in FIG. 5 is used for transfer molding the molded product 21 shown in FIG.
2, 43, 44, and these split molds 41, 42, 4
It has a cavity 45 surrounded by 3 and 44. An injection port 47 for injecting a molding material (not shown) from the material reservoir 46 into the cavity 45 is provided in one split mold (upper die) 41, and a plurality of the injection ports 47 are equally distributed in the circumferential direction. Have been. Reference numeral 48 denotes a piston for pressing the molding material.

However, there is room for improvement in the productivity of transfer molding of the molded article 21 shown in FIG. 4, and therefore, injection molding of the molded article 21 has recently been studied. . When the molded article 21 is injection-molded, a molding die shown in FIG. 6 is used.

That is, the molding die shown in FIG. 6 is a molded product 2 shown in FIG.
1 is injection-molded, and a plurality of split molds 1, 2, 2,
3, 4, 5, and these split types 1, 2, 3, 4, 5
And has a cavity 6 surrounded by. An injection port for injecting a molding material (not shown) into the cavity 6 via the sprue 8 and the runner 9 from the nozzle touch portion 7 into one split mold (upper mold) 1 and the lower split mold (middle mold) 2. A plurality of runners 9 and injection ports 10 are arranged in the circumferential direction.

However, the mold of FIG. 6 has the following problems.

That is, as shown in an enlarged view in FIG. 7, in the molding die of FIG. 6, the injection port 10 is formed in a tapered funnel shape like the molding die of FIG. The tip portion 10a having the smallest inner diameter is open to the cavity 6 as it is. Therefore, when the high-temperature short-time vulcanization, which is the aim of injection, is carried out, the temperature becomes 30 to
Since the pressure becomes extremely high at 40 ° C. and 3 to 6 times, sinks occur in the rubber portion 24 due to the release of pressure after molding, and a concave trace 25 occurs in the rubber portion 24 as shown in FIG. I do. The concave trace 25 has a size far exceeding an allowable value set according to a general standard, and the rubber portion 24 may be damaged depending on the specification or use conditions of the item such as the shape or use of the molded product 21. There is a possibility that it will be done.

[0009]

In order to solve the above problem, it is conceivable to lengthen the tip 10a of the injection port 10 straight while maintaining its inner diameter as shown in FIG. However, in this case, the state of the trace remains unstable, and when the rubber is cut off above the straight tip portion 10a, as shown in FIG. 10, a concave trace 25 and a convex trace remain. In the case where 26 occurs in a mixed state and the rubber is cut below the straight tip portion 10a, as shown in FIG. 11, a concave trace 25 which is not different from the state of FIG. 8 occurs. And it is mixed.
In each case, the size of the trace remains far beyond the allowable value.

[0010]

SUMMARY OF THE INVENTION In view of the above, the present invention has been devised to solve the above-mentioned problems, and in order to achieve this object, a cylinder head cover and a plastic cover are required.
Plug tube gasket to seal between tube
Mold for injection molding the rubber part of
A counterbore portion having a diameter larger than the inner diameter of the front end portion of the injection port is provided on the front end side of the injection port into which the molding material is injected .

[0011]

According to the present invention, if a counterbore portion having a diameter larger than the inner diameter of the tip of the injection port is provided on the tip side of the injection port, traces generated on the molded product are limited to those having a convex shape. In other words, it is possible to prevent the occurrence of a concave trace that causes damage to the rubber portion due to the specifications or use conditions of the item such as the shape or use of the molded product. In addition, the convex traces themselves do not become so large due to sink marks after molding.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the present invention will be described with reference to the drawings. The molding die is a molded product 21 shown in FIG. 4, that is, a cylinder head cover and a plug similarly to the molding die shown in FIG.
Plug tube gasket 2 to seal between tubes
The first rubber portion 24 is injection molded.

As shown in FIG. 1, the molding die has a plurality of split dies 1, 2, 3, 4, and 5, and is surrounded by these split dies 1, 2, 3, 4, and 5. Having a cavity 6. An injection port 10 for injecting a molding material (not shown) into the cavity 6 from the nozzle touch portion 7 through the sprue 8 and the runner 9 to one split mold (upper mold) 1 and the lower split mold (middle mold) 2. Are provided, and a plurality of the runners 9 and the injection ports 10 are equally arranged in the circumferential direction. FIG. 2
As shown in the enlarged view, a counterbore portion 11 having a substantially disc shape and having a diameter larger than the inner diameter of the tip portion 10a of the injection port 10 is provided on the tip side (cavity 6 side) of the injection port 10. The counterbore 11 has a predetermined volume. The tip 10a of the inlet 10 is formed straight over a predetermined length.

The molded article 2 is formed by the mold having the above-described structure.
When injection molding 1 is performed, traces 26 generated on the rubber portion 24 of the molded product 21 are limited to convex shapes as shown in an enlarged view in FIG. It is possible to prevent the occurrence of concave traces which may cause the rubber portion 24 to be damaged due to the specification or use conditions of the item, and the convex traces 26 themselves are formed by sink marks after molding. Is not so large. Therefore, it is possible to constantly provide a molded product 21 that satisfies the tolerance with respect to the problem of the trace remaining after molding.

The inner diameter of the counterbore 11 is, for example, 0.5 mm in actual diameter of the tip 10a of the inlet 10.
Is about 1.0 mm.

[0016]

[Effect of the proposed Invention The present invention, the effects of the following. That is, there is a gap between the cylinder head cover and the plug tube.
Injection molding of rubber part of plug tube gasket
A molding die that injects molding material into the cavity. <br/> A mark formed on a molded product because a counterbore portion having a diameter larger than the inner diameter of the distal end portion of the injection port is provided at the distal end side of the injection port. The remainder is limited to convex ones, and it is possible to prevent the occurrence of concave traces that may cause damage to the rubber part due to the specifications or use conditions of the item such as the shape or use of the molded product. It becomes possible. Moreover, the protruding trace itself does not become so large due to sink after molding. Therefore, regarding the problem of traces that occur after molding,
It is possible to constantly provide a molded product that satisfies the tolerance. The molded product is the cylinder head cover and plastic
Plug tube gasket to seal between tube
, The rubber part of this plug tube gasket
When concave traces occur, the rigidity of the lip waist varies.
The possibility of cracks remains, but as in the present invention
By providing a large counterbore at the tip of the inlet,
Uniform rigidity can be secured at the waist.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a mold according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a main part of the mold.

FIG. 3 is a sectional view of a main part of a molded product molded by the molding die.

FIG. 4 is a sectional view of a molded product.

FIG. 5 is a cross-sectional view of a transfer mold according to a conventional example.

FIG. 6 is a sectional view of a molding die for injection molding.

FIG. 7 is an enlarged sectional view of a main part of the mold.

FIG. 8 is a cross-sectional view of a main part of a molded product molded by the molding die.

FIG. 9 is a sectional view of a main part of an improvement plan of the molding die.

FIG. 10 is a cross-sectional view of a main part of a molded product molded by the molding die.

FIG. 11 is a cross-sectional view of a main part of a molded product molded by the molding die.

[Explanation of symbols]

 1, 2, 3, 4, 5 Split mold 6 Cavity 7 Nozzle touch part 8 Sprue 9 Runner 10 Inlet 10a Tip part 11 Counterbore part 21 Molded product 22 Reinforcement ring 23 Garter spring 24 Rubber part 25 Concave trace 26 Convex Trace remains

Claims (1)

(57) [Scope of request for utility model registration] (1)Cylinder head cover and plug tube
Plug tube gasket (21) to seal between the tubes
A mold for injection-molding the rubber portion (24) of Injection port (10) for injecting molding material into cavity (6)
On the tip side of Of the tip (10a) of the inlet (10)
A special feature is that a counterbore (11) with a larger diameter than the inner diameter is provided.
The molding die to be used.