JPH10202691A - Molding method for rubber and resin composite body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the strength and rigidity of molding resin by changing the positions of an injection gate, injecting a plurality of times, increasing the injection pressure successively and applying the optimum pressure for resin in the last injection. SOLUTION: An innermost layer 8 of a resin bracket is molded by injection molten resin from an injection gate 7a into a cavity 4a for forming a bracket layer outside a rubber bush 3 and a core 6 in a mold 2a in the first injection molding. Then an intermediate layer 9 of the resin bracket 1 is molded by injecting molten resin from an injection gate 7b into a cavity 4b of a mold 2b outside the resin layer 8 molded in the first injection molding. In the last injection, resin is injected outside the intermediate layer 9 molded in the second injection to mold an outermost layer 10 of the bracket and mold the final bracket shape. The generation of voids at the time of molding can be controlled by the arrangement.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for molding a rubber / resin composite suitable for producing a resin bracket for an engine mount. More specifically, it is possible to prevent a decrease in the strength of a weld line portion that occurs during resin injection molding, and to suppress the occurrence of voids in the resin during the molding process, and to obtain a rubber-resin composite having sufficient strength and rigidity. It relates to a molding method.

[0002]

2. Description of the Related Art As an anti-vibration material for an engine mount, a metal bracket having a rubber bush is used, but a resin bracket has been developed in order to reduce the weight of a vehicle and improve corrosion resistance. By using a resin material for the bracket, various advantages are conceivable, such as a reduction in weight as well as an improvement in corrosion resistance and an expectation of a vibration suppression effect due to the vibration damping property of the resin. However, resin materials have a problem in strength as compared with metals.

[0003] That is, as shown in FIG. 2, a resin bracket 1 is provided with a rubber bush 3 formed by applying an adhesive to a resin molding die 2 and a vulcanized molded bush 3 together with a core 6. The cavity 4 is molded by injecting a molten resin such as polyamide from the gate 7. This injection molding is carried out at a low speed to suppress deformation of the rubber bush 3.
Although it is necessary to perform the injection molding at a low pressure, when the injection molding is performed at a low speed and a low pressure, there is a problem that voids (small holes) are generated in the resin and the strength is reduced.

In addition, in this injection molding, a weld line 5 having a low resin strength is formed on the opposite side of the resin injection gate. Particularly, in the injection molding at a low speed and a low pressure, the strength at the weld line 5 is remarkably reduced, and as a bracket. It is difficult to obtain sufficient strength.

Moreover, recently, a bracket having higher strength and rigidity has been demanded for a high-performance automobile, and the resin portion tends to be thicker, so that a resin bracket which can be satisfied by low-speed and low-pressure injection molding is obtained. Making it even more difficult.

[0006]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a molding method capable of solving the above-mentioned problems and producing a rubber / resin composite having improved strength and rigidity of a molding resin. Another object of the present invention is to provide a method of molding a rubber-resin composite, which can increase the thickness of a molding resin.

[0007]

The inventor of the present invention changed the gate position of the molten resin and performed injection several times to form the resin into a layer, and increased the injection pressure sequentially for each injection to make the resin injection at the final injection. By adjusting the injection pressure to the optimum value, it was found that the generation of voids in the resin was suppressed, the weld line positions were dispersed, and the reduction in strength at the weld line portion was suppressed, and the present invention was completed.

That is, the present invention provides the following method for forming a rubber / resin composite. 1) In a molding method for producing a rubber / resin composite by injecting a resin to the outside of a vulcanized rubber molded body set in an injection molding die, a plurality of injections are performed by changing the position of an injection gate, and injection is performed. A molding method characterized by sequentially increasing a pressure to obtain an optimum pressure of a resin in a final injection. 2) The molding method according to 1 above, wherein the vulcanized rubber molded body is a vibration-proof rubber. 3) The above 1 wherein the same resin material is used for the plurality of injections.
Molding method. 4) The above 1 wherein different resin materials are used for the plurality of injections.
Molding method. 5) The molding method as described in 1 to 4 above, wherein the resin is a polyamide.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described with reference to the drawings, taking a molding method for manufacturing a resin bracket for an engine mount as an example. FIGS. 1A, 1B, and 1C are schematic cross-sectional views showing steps of molding a resin bracket 1 having a rubber bush 3 in the center by three injections according to the method of the present invention. a) First injection, FIG.
FIG. 1B shows the second injection, and FIG. 1C shows the final injection.

First injection The first injection is for forming the innermost layer, and is shown in FIG.
As shown in (a), a vulcanized rubber bush 3 having an inner cylindrical portion at the center is set together with a core 6 in a first injection molding die 2a. It is preferable to apply an adhesive to the rubber bush 3 in advance in the same manner as in the related art in order to improve the adhesiveness with the resin. Rubber bush 3 in mold 2a
The molten resin is injected and injected from the injection gate 7a into the cavity 4a for forming the bracket layer outside the core 6 and the innermost layer 8 of the resin bracket is formed. A weld line 5a is formed in the resin layer opposite to the injection gate 7a. At this time, the resin material is injected at a low pressure in order to suppress the deformation of the rubber bush 3 inserted therein, but by reducing the thickness of the resin layer, it is possible to suppress the occurrence of voids which has conventionally caused a decrease in strength.

Second injection The second injection is for forming an intermediate layer, and the molded body obtained by the first injection molding is taken out of the mold and, as shown in FIG. Is set in the injection mold 2b. The molten resin is injected and injected from the injection gate 7b into the cavity 4b of the mold 2b outside the resin layer 8 formed in FIG. 1A to form the intermediate layer 9 of the resin bracket 1. The injection gate 7b is set so that the weld line is located at a different position from the weld line formed by the first injection. In the illustrated example, the weld line 5 is formed by the first injection.
The injection gate 7b is provided at substantially the same position as the first welding line 5b.
a. Injection conditions include
Since the innermost layer 8 of resin is formed outside the rubber bush 3 by the first injection, the deformation of the rubber bush 3 is suppressed in the second injection, and the pressure of the second injection is the first injection pressure. Than can be higher. Therefore, even if the resin layer 9 formed by the second injection is thicker than the resin layer 8 formed by the first injection, voids are hardly generated.

Final injection The final injection is for forming the outermost layer and is shown in FIG.
As shown in (c), the molded body obtained by the second injection is taken out of the mold and set in the final injection molding mold 2c. In the final injection, a resin is injected to the outside of the molded body obtained by the second injection to form the outermost layer 10 of the bracket, and is formed into a final bracket shape. The position of the injection gate 7c is set so that the weld line is different from the weld lines 5a and 5b formed by the first and second injections. In the illustrated example, the injection gate 7c includes a first injection injection gate 7a and a second injection injection gate 7a.
b, and the weld line 5c exists between the first weld line 5a and the second weld line 5b, substantially opposite to the injection gate. The injection conditions of the final injection are as follows: the resin layer 8 by the first and second injections;
Since there is the step 9, there is almost no need to consider the deformation of the rubber bush 3, and it can be performed under the optimum injection conditions (temperature, pressure, etc.) of the resin material to be used which is higher than the pressure at the time of the second injection. Since the optimum injection condition is adopted, the outermost layer 1
At 0, no void is generated.

Further, since the pressure is increased in the second injection and the third injection, the injection pressure has an effect of caulking and the adhesion between the layers is improved. In addition, a uniform compressed state can be formed for rubber.

In the above, an example in which injection molding is performed three times has been described. However, injection molding by two times and molding by four or more injections in which the formation of the intermediate layer is performed a plurality of times can be performed in the same manner as described above. it can. In the above-described example, the mold is changed for each injection. However, multi-color molding, DSI,
If a technique such as DRI is used, a finished molded product can be obtained without changing the mold.

The resin material that can be used in the molding method of the present invention is preferably one having excellent injection welding properties.
In the case of manufacturing a member requiring strength such as a resin bracket, a material having high strength and rigidity is used. Suitable for engine mounting plastic brackets,
In particular, polyamide is mentioned, and more preferably a material reinforced with glass fiber or the like, for example, 2020GC6 (Ube Industries, Ltd., PA66-GF30%), 1011GC6
(Made by Ube Industries, PA6-GF30%), and those modified with various denaturants to improve adhesion (welding) properties, for example, 2123GU6 (Ube Industries, made, modified PA66-GF30%), 1015 GNK
(30% modified PA6-GF, manufactured by Ube Industries). These resins are excellent in weldability and have sufficient strength, and are particularly preferable as the resin material of the method of the present invention.

In the present invention, since the resin is formed into a plurality of layers, if the adhesion between the layers is sufficient, a different resin material can be used for each layer to provide a special function. For example, as the outermost layer, polyamide 46, semi-aromatic nylon (Zytel HTN)
(DuPont), Ultramid 6T (BASF), Lenny (Mitsubishi Engineering Plastics) or other high-strength resin, or a calcium chloride resin such as polyamide 612 or 610, or the outer layer has low adhesion but heat resistance and liquid resistance. Adhesion to inner layer using resin (PPS: polyphenylene sulfide, etc.) excellent in slidability, resin excellent in slidability (POM: polyacetal, etc.), resin excellent in light weight and water resistance (PA66 / PP alloy, etc.) Resins having excellent properties can also be used.

The rubber material used as the rubber bush in the present invention is not particularly limited. However, when the rubber material is applied to a place where vibration proof is required, such as a rubber bush of a resin bracket, the vibration proof property and the durability can be improved. A vibration-proof rubber material having excellent properties and the like is preferable.

[0018]

As described above, according to the molding method of the present invention, the weld line is dispersed by changing the injection gate of the injection resin a plurality of times to increase the injection pressure for each injection, and the final injection is performed. The generation of voids during molding can be suppressed, and the position of the weld line is dispersed, so that a molded body having excellent strength and rigidity can be obtained. Further, it is easy to increase the thickness of the resin. INDUSTRIAL APPLICABILITY The method of the present invention can be used for vibration-proof rubbers such as engine torque rods, suspension rods, torsional dampers, and steering couplings, in addition to molding resin brackets for engine mounts.

[Brief description of the drawings]

FIG. 1 is an explanatory view of each molding step showing an example of the production of a resin bracket by the molding method of the present invention, wherein (a) shows the formation of an innermost layer of the resin bracket, (b) shows the formation of an intermediate layer,
(C) shows the formation of the outermost layer.

FIG. 2 is an explanatory view of a conventional resin bracket molding.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 resin bracket 2, 2 a, 2 b, 2 c resin molding die 3 rubber bush 4, 4 a, 4 b, 4 c cavity 5, 5 a, 5 b, 5 c weld line 6 core 7, 7 a, 7 b, 7 c injection gate 8 innermost layer 9 Middle layer 10 Outermost layer

Claims (5)

[Claims] In a molding method for producing a rubber-resin composite by injection molding a resin outside a vulcanized rubber molded body set in an injection molding die, a plurality of injections are performed by changing the position of an injection gate. A molding method characterized by sequentially increasing the injection pressure to obtain the optimum pressure of the resin in the final injection. 2. The molding method according to claim 1, wherein the vulcanized rubber molded body is a vibration-proof rubber. 3. The molding method according to claim 1, wherein the same resin material is used for the plurality of injections. 4. The molding method according to claim 1, wherein different resin materials are used for the plurality of injections. 5. The resin according to claim 1, wherein the resin is a polyamide.
The molding method according to any one of the above items.