JP2001322141A - Method for molding cover and gasket - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for molding a cover which is fixed surely to a gasket, with a correct fitting position kept without generating thermal deformation, holds good elasticity, and demonstrates strong seal performance, and the gasket. SOLUTION: In a method for molding/integrating the cover and the gasket 1, a gasket insertion groove 32 having a rise part 31 is arranged in the flange part of a molding mold 3, the gasket 1 is inserted into the groove 32, and a synthetic resin material is injection-molded. In this way, the gasket 1 is prevented from falling, and the degree of freedom of gasket design is improved to enable the pursuit of high seal performance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding method for molding a casing made of a thermoplastic resin and a sealing material made of an elastic material, and more specifically, to molding a cover as a casing and a gasket as a sealing material. It relates to improvement of a molding method for integration.

[0002]

2. Description of the Related Art Conventionally, as a method for producing a composite article in which an elastic sealing material is molded on an article made of a synthetic resin, for example, there is a molding method disclosed in Japanese Patent Publication No. 63-45292.

[0003] This involves molding a plastic molded body on one side of a pair of molds that can be replaced with each other, and then replacing the molded body with one side of the other mold while holding the molded body in one mold. An elastic sealing material is formed on the sealing surface of the molded body. Recently, from such a molding method,
It is changing to a simple, mass-productive molding method that uses a gasket as an insert material to mold the cover body. (See Japanese Patent Application Laid-Open No. 7-208261)

[0004]

However, such a gasket formed integrally with the cover is buried deep in the flange portion of the cover in order to prevent falling off and to secure an elastic mass. As shown, the head of the gasket 1 is undercut or the like so that the buried portion has a large volume. In addition, a method of securely inverting and fixing the material inflow during molding is completely considered. Since the gasket 1 formed in this way has a portion that is exposed from the surface of the flange portion 21 inevitably lacking in elastic mass, and has no deformation allowable space, it is mounted and compressed by compression. The compression set was low, such as the deformation flow was immediately restricted and the elasticity was easily lost. The present invention has been devised in view of such a drawback, and is reliably fixed while maintaining an accurate mounting position without causing thermal deformation of the gasket, maintaining good elasticity and having strong sealing performance. The purpose is to provide a cover and gasket molding method that can be used.

[0005]

The present invention will be described in detail with reference to the drawings. As shown in FIG. 1, a synthetic resin material used for a timing belt cover, a water inlet cover, a water outlet cover, a cylinder head cover, an oil pan and the like. 2 and a gasket 1 made of an elastic material such as synthetic rubber or a soft synthetic resin. A gasket insertion groove 32 having a rising portion 31 is arranged, a gasket 1 formed in advance from an elastic body is fitted into the gasket insertion groove 32, and then clamped, and a molten synthetic resin material is injected and cured. As shown in FIG. 2, a cover 2 integrated with a gasket 1 is molded.

[0006] The cover 2 formed and integrated in this manner.
The gasket 1 is characterized in that a recess 32 is formed on the side surface of the gasket 1 by the trace of the rising portion 31 provided on the flange portion of the mold 3 as shown in FIG.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to a cover 2 as described above.
Is formed of a synthetic resin material, a gasket 1 made of an elastic material, which is formed in advance, is placed in a molding die 3 and a molten synthetic resin material is injected and cured.
When the gasket 1 is placed on the molding die 3 as shown in FIG. 1, when the gasket 1 is inserted into the gasket insertion groove 32, the rising portion 31 provided on the flange portion serves as a guide for the gasket 1 to guide the gasket 1 to be fitted accurately. None, when the cover 2 is formed, the rising portion 31 serves as a shield against the flow pressure of the synthetic resin material, and is securely fixed and arranged while maintaining an accurate mounting position. When the fitting portion of the gasket 1 fitted into the gasket insertion groove 32 is formed into an undercut shape (not shown) wider or thicker than the exposed portion, the gasket insertion groove 32 is more firmly fixed and synthesized. It shows a large fixed holding force against the flow pressure of the resin material.

In the flange portion 21 of the cover 2 formed and integrated as described above, a concave space 4 is formed on the side surface of the gasket 1 as shown in FIG. When the cover 2 is mounted on the mounting member 5 and tightened, as shown in FIG. 3, the gasket 1 has a deformable space provided by the concave space 4 on the side surface, so that the gasket 1 absorbs flow deformation with a margin and reduces its elasticity. High sealing force can be maintained for a long time without loss.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A rising portion 31 formed on a flange of a molding die according to the present invention has a purpose of holding a gasket 1 and securing a deformation allowable space. , But it is preferable that the deformation amount is provided in a range not exceeding the recessed space 4. According to this setting, as shown in FIG. 3, when the cover 2 is mounted on the mounting member 5 and tightened, the cover 2 comes into contact with the end face of the mounting member 5 to be closed. The sealing force is exerted while maintaining the elasticity of the recessed space 32.

In forming the cover 2, a synthetic resin material such as polyamide (PA6, PA66, PPA, PAMXD6, etc.), polyacetal, polycarbonate, ABS resin, etc. is used, heated, melted and injected into a mold. Formed. On the other hand, in the molding of the gasket 1, rubber-based resins and thermoplastic elastomers are suitable, and acrylic rubber, nitrile rubber, water-added nitrile rubber, butyl rubber, styrene-butadiene copolymer, ethylene-vinyl acetate copolymer are preferred. It is a polymer, an ethylene-methyl acrylate copolymer, an ethylene-ethyl acrylate copolymer, or the like, and may be a natural rubber, a butadiene rubber, a silicone rubber, an ethylene propylene rubber, or the like.

[0011]

According to the present invention, the gasket 1 is prevented from falling down in the gasket insertion groove 32 by the rising portion 31 provided on the molding die 3 of the gasket 1, so that the cover 2 can be formed by injection molding with a synthetic resin material. Since the shape is maintained robustly, the degree of freedom in gasket design is increased, and higher sealing performance can be pursued. In addition, the cover 2 and the mounting member 5 can be closed in the recessed space 4 according to the present invention, so that the sealing performance can be improved with an increase in the margin of the gasket 1. In addition, a sufficient elastic mass can be secured in the exposed portion of the gasket 1, which is also a factor that can maintain good elasticity.

[Brief description of the drawings]

FIG. 1 is an explanatory view of an embodiment of the present invention before molding.

FIG. 2 is a sectional view showing a state before tightening of a product.

FIG. 3 is a cross-sectional view showing a state closed from FIG. 2;

FIG. 4 is a sectional view showing a conventional structure not using the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Gasket 21 Flange part 2 Cover 3 Mold 31 Rising part 32 Gasket insertion groove 4 Depression space

Claims (3)

[Claims] In a method of molding a cover and a gasket, wherein a cover made of a synthetic resin material and an elastic gasket are molded and integrated, a gasket insertion groove having a rising portion is arranged on a flange portion of the cover in a molding die, and the elasticity is previously determined. A method of molding a cover and a gasket, comprising: inserting a gasket formed from a body into the gasket insertion groove, injecting a molten synthetic resin material, and curing the resin to mold a cover integrated with the gasket. 2. The method of molding a cover and a gasket according to claim 1, wherein the cover and the gasket molded as described above have a recessed space on a side surface of the gasket in the flange portion. 3. The method of molding a cover and a gasket according to claim 1, wherein the fitting portion of the gasket fitted into the gasket insertion groove has an undercut shape.