JPS6345932B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of injection molding a member made of fiber reinforced plastic (FRP).

Current FRP has glass or carbon fiber mixed into resin such as nylon. Glass fiber, which is the above-mentioned contaminant, is cheap, but has a high specific gravity.
Carbon fiber has a low specific gravity and good mechanical properties, but is expensive.

For this reason, FRP mixed with glass fiber is cheap but heavy, and FRP mixed with carbon fiber is expensive.
Although FRP is light and has good mechanical properties, it is expensive.

Taking these characteristics into consideration, we designed an intake manifold b whose one end is fixed in the form of a cantilever to the highly rigid cylinder head a, as shown in Figure 1.
If you try to construct it using FRP, the overall weight will be large if the FRP is mixed with glass fibers, and the fixed part by cantilever support must be made into a shape that has high strength against fatigue, making it difficult to mold.

On the other hand, FRP mixed with carbon fibers does not have the above problems because it is light and has high strength, but it does have the problem of being expensive.

In order to solve this problem, one idea is to partially change the material and use FRP mixed with carbon fiber in the parts that require strength, and FRP mixed with glass fiber in other parts. It will be done.

However, with conventional FRP, it has not been possible to obtain injection molded products made of different materials.

This is because when such parts are injection molded using different materials using different injection nozzles, due to the differences in the physical properties of each material, they do not fuse well at the boundaries and the strength of these parts becomes weak. be.

The present invention was developed in consideration of the above-mentioned problems, and it is possible to inject parts using FRP with partially different mixed fibers while thoroughly merging the boundaries, thereby eliminating extreme changes in physical properties at the boundaries. The object of the present invention is to provide an injection molding method for a fiber-reinforced plastic member that can be molded without causing a decrease in strength at the boundary.

The embodiment will be described below with reference to FIG.

In the figure, 1 is an intake manifold, which is an example of a part to be injection molded by the method of the present invention, and its base end 1a is attached to the engine side.
An air cleaner or the like is attached to the distal end 1b, and a larger stress is applied to the proximal end 1a.

When injection molding this intake manifold 1,
As shown in FIG. 3, gates 3a, 3b, and 3c are provided at the proximal end 2a, distal end 2b, and intermediate part 2c of the mold 2 for this manifold, respectively. Injection cylinders 4a and 4b of different injection molding materials are connected to the gate 3b of the tip portion 2b, and the gate 3c of the intermediate portion 2c is connected to both injection cylinders 4a and 4b.

Therefore, the two sets of different injection cylinders 4a,
FRP mixed with carbon fiber is simultaneously injected from one side of the gate 4b to the gate 3a on the proximal side, and FRP mixed with glass fiber is simultaneously injected from the other side to the gate 3b on the distal side.

Thus, both of the above FRPs each have gate 3.
The FRPs are injected into the mold from a and 3b, and at the same time, both FRPs are merged and mixed and injected from the intermediate gate 3c.

Therefore, the manifold molded with this mold 2 has carbon fiber mixed in its base end 1a.
The tip part 1b is made of FRP mixed with glass fiber, and the middle part is made of FRP which is a mixture of the above two FRPs.

At this time, the FRP injected into the intermediate part is a mixture of FRP with different physical properties injected into the proximal end and the distal end, so it is well fused with both FRPs and does not create a clear boundary. No extreme change in physical properties occurs in this portion, and the strength of this portion does not particularly decrease.

The present invention is as described above, in which at least three gates 3a, 3b, 3c are provided in an injection molding mold a, the positions of which are shifted in a certain direction. Fiber-reinforced plastics having different physical properties are injected from gates 3a and 3b located in the middle, and fiber-reinforced plastic in a state where both of the above-mentioned fiber-reinforced plastics are mixed is injected from gate 3c located in the middle. When molding a molded member using fiber-reinforced plastics with physically different physical properties, the molding can be done without any loss of strength at the boundary between the two fiber-reinforced plastics, and the proximal end can be shaped like an engine intake manifold. By using fiber-reinforced plastics with partially different physical properties, it is possible to easily mold a member for which it is desired to have higher strength than other parts, and to provide the necessary and sufficient strength.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the attachment relationship between the engine and the intake manifold, FIG. 2 is a front view of the intake manifold, and FIG. 3 is a sectional view schematically showing an injection molding die for the intake manifold. 2 is an injection mold, and 3a, 3b, and 3c are gates.

Claims (1)

[Claims] 1 Into an injection mold 2 in which at least three gates 3a, 3b, 3c are provided with their positions shifted in a certain direction, from the gates 3a, 3b located on both sides of the gates 3a, 3b, 3c, respectively. A fiber-reinforced plastic member characterized in that fiber-reinforced plastics having different physical properties and a mixture of the two fiber-reinforced plastics are injected from a gate 3c located in the middle. Injection molding method.