JPS6352571B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel resin injection molding method (hereinafter simply referred to as RI molding method).

The RI molding method is used to fabricate fiber-reinforced plastics (hereinafter referred to as
It is a type of molding method for FRP (simply referred to as FRP), and belongs to the contact pressure molding method along with the hand lay-up method, spray-up method, etc., but it has the advantage of higher productivity compared to other contact pressure molding methods. be.

The RI molding method generally uses a pair of male and female molds made of FRP, etc. A preform of reinforcing fiber such as glass fiber is placed in the mold in advance, the mold is closed, and unsaturated polyester is then injected through injection holes placed at appropriate positions. This is a method of press-filling a curable resin such as resin, plugging the injection hole, and curing and molding at a low temperature (for example, room temperature to about 50°C).The basic molding process is as follows.
(1) Mold cleaning and mold release treatment (in some cases, gel coat layer formation may also be performed), (2) preform filling (including core material filling), (3) mold closing, (4) clamping,
It consists of (5) injection of curable resin, (6) curing, (7) mold opening, (8) demolding, and (9) post-processing (burring, after-curing, etc.).

In the conventional RI molding method, the curable resin is injected into the mold as follows.

FIG. 1 is a schematic explanatory diagram showing the conventional RI molding method. 1 is a male mold, 2 is a female mold, and by combining the male mold 1 and the female mold 2, a cavity 3 is formed.
is formed. Sealing rings 4 and 5 such as rubber packing are placed between the mating surfaces of the outer peripheries of the male mold 1 and the female mold 2.
is mediated. Reference numeral 6 denotes an air vent hole for evacuating the inside of the cavity 3, and is connected to a vacuum system. 7 is an injection hole for the curable resin 8. To inject the curable resin into the cavity 3, air is removed from the air vent hole 6 to create a vacuum inside the cavity 3, and the curable resin is injected from the injection hole 7.

However, in such a conventional method, the air vent hole 6
Since the air vent hole 6 is provided in a part that opens directly into the cavity 3, if the position of the air vent hole 6 is not appropriate, if the resin enters the cavity 3 before the air escapes, the air vent hole 6 will be blocked and the air will not be able to enter the cavity 3. There are problems such as pinholes remaining in the resulting FRP molded product, or an increase in material loss if you try to completely remove the pinholes.

In view of the above points, the present invention ensures air removal in the cavity of the RI mold and provides excellent quality.
The object of the present invention is to provide an RI molding method that can produce FRP molded products.

That is, the present invention provides an RI mold with a double sealing ring interposed between the mating surfaces of the mold, and an inclusion that allows air to pass through between the inner peripheral sealing ring and the mold, but substantially prevents resin from passing through. is arranged to create a negative pressure in the space between the inner circumferential sealing ring and the outer circumferential sealing ring, the air in the cavity is removed through the inclusion, and the curable resin is injected and molded. Regarding the RI molding method.

Next, the method of the present invention will be explained based on the drawings.

FIG. 2 is a schematic explanatory diagram showing one embodiment of the method of the present invention, and FIG. 3 is an enlarged view of the main part of FIG. 2. 11 is a male mold of the RI mold, 12 is a female mold,
A cavity 13 is formed by combining the male mold 11 and the female mold 12. Sealing rings 14 and 15 are interposed between the mating surfaces of the outer peripheries of the male mold 11 and the female mold 12. Inner circumference sealing ring 14 and male mold 1
1 and the female mold 12 is provided with an intervening member 16 that allows air to pass through but substantially prevents the resin from passing through.
Reference numeral 17 denotes an air vent hole, which is provided so as to open into the space 18 between the sealing ring 14 and the sealing ring 15, and the other end is connected to a vacuum system (not shown). 19 is an injection hole for the curable resin 20, and is connected to a supply pump (not shown).

In order to inject a curable resin into the cavity 13 of the RI mold configured as described above, the air is evacuated from the air vent hole 17 to create a negative pressure in the space 18. The air is exhausted to the outside through the space 18 through the gap between the inserts 16 disposed between the molds. When the inside of the cavity 13 is brought to a negative pressure of about 0.3 to 0.7 kg/cm ² G in this way, the curable resin 20 is injected through the injection hole 19 and hardened.

In the present invention, the sealing ring is provided twice as described above, the specific inclusion 16 is disposed between the sealing ring 14 on the inner periphery and the mold, and the air vent hole 17 is formed into a cavity as in the conventional example. 1
3, but is provided so as to open into the space 18 between the inner circumferential sealing ring 14 and the outer circumferential sealing ring 15, thereby creating a negative pressure in the space. When the space 18 is made to have a negative pressure, the air inside the cavity 13 is exhausted through the inclusion 16 disposed between the sealing ring 14 and the mold. Since it surrounds the cavity 13, it becomes possible to exhaust air from the entire outer periphery of the cavity 13. Therefore, even if the curable resin is injected into the cavity 13, the air can be exhausted from any part of the outer periphery of the cavity 13, and the air can be removed reliably. The resulting FRP molded product does not have defects such as pinholes.

In the present invention, the inclusion 16 disposed between the inner circumferential sealing ring 14 and the molding die allows air to pass therethrough, but substantially prevents the curable resin from passing therethrough. Such inclusions usually include glass fibers,
Fibrous materials such as vinylon fibers are used. These fibrous materials may be used in the form of cloth, mat, etc. Furthermore, the terminals of reinforcing fibers such as glass fibers may be inserted into the product.

The sealing rings 14, 15 are usually made of rubber. The sealing ring 15 on the outer periphery is the space 1
8 is installed to completely seal it from the outside.

The RI molding method of the present invention may be performed in the same manner as the conventional method except that the air inside the cavity is vented as described above.

[Brief explanation of drawings]

Figure 1 is a schematic explanatory diagram showing the conventional RI molding method.
FIG. 2 is a schematic explanatory diagram showing an embodiment of the RI molding method of the present invention, and FIG. 3 is an enlarged view of the main part of FIG. 2. Main symbols in the drawings, 11, 12: Molding mold, 13:
Cavity, 14, 15: Sealing ring, 16: Inclusion, 17: Air vent hole, 19: Injection hole.

Claims (1)

[Claims] 1. In a resin injection mold, a double sealing ring is provided between the mating surfaces of the mold, and there is an inclusion between the inner sealing ring and the mold that allows air to pass through but does not substantially allow the resin to pass through. The method is characterized in that the space between the inner circumferential sealing ring and the outer circumferential sealing ring is placed under negative pressure, air is removed from the cavity through the inclusion, and a curable resin is injected and molded. Resin in-die extension molding method.