JPS6319321B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for molding a reaction injection molded product having a core material.

[Conventional technology]

Reaction injection molding is generally called RIM (Reaction
Injection Molding) (hereinafter referred to as RIM)
(referred to as molding), two types of low-molecular resin liquids are mixed immediately before molding and injected into a closed mold, and the two liquids are rapidly reacted within the mold to polymerize.
This mixing process immediately before molding is carried out in two parts: the mixing head part on the molding machine side and the aftermixer part on the mold side.
It is usually carried out in successive stages. Mixing only by the mixing head on the molding machine side will result in 2
Mixing of the liquids becomes insufficient, and unreacted areas occur both inside and on the surface of the molded product due to poor mixing.
Therefore, in order to obtain reaction injection molded products of good quality, an after mixer is installed on the mold side, and two
Perfect mixing of liquids has become essential.

Conventionally, when molding a reaction injection molded product having a core material, such as an air spoiler for an automobile, a molding method as shown in FIGS. 4 and 5 has been used.

In FIGS. 4 and 5, 1 is a mold, and this mold 1 consists of a lower mold 2 fixed in a fixed position and an upper mold 3 that opens and closes by moving up and down relative to the lower mold 2. . Further, a lower half 5 and an upper half 6 of an aftermixer 4 are fixed to the lower mold 2 and the upper mold 3, respectively.

For molding, the mixing head 7 of the molding machine is attached to the lower half 5 of the after mixer 4, the mold is opened, and the cavity surface 3 of the upper mold 3 is opened.
After fixing the core material 8 to a, the mold is closed and clamped, and a synthetic resin stock solution such as polyurethane is injected. At this time, the nozzle 7a of the mixing head 7 is fitted into the nozzle opening 9 of the aftermixer 4. The stock solution is then transferred from the nozzle 7a of the mixing head 7 to the after mixer section 10, the runner 12 having a reservoir section 11, and the film gate 1.
3 into the cavity 2a of the mold 1. The reservoir portion 11 is provided to ensure that the stock solution is evenly injected over the entire length of the film gate 13.

After this molding, the mold is opened and the molded product is taken out. In this case, the molded product includes an after mixer section 10, a runner section 12 including a reservoir section 11, and a film gate 13.
The parts are removed while still connected together.

[Problem that the invention seeks to solve]

In the conventional molding method as described above, the raw material of the runner 12 including the aftermixer section 10 and the reservoir section 11 is wasted. In addition, the after mixer section 10 and the runner 12 section must be provided on the parting line surface (mold matching surface) of the lower mold 2 and upper mold 3, so the gate section should be located at the corner adjacent to the surface side of the molded product. The gate finishing marks will deteriorate the appearance of the product.

The present invention aims to solve the above-mentioned problems, and aims to eliminate waste of material by not providing an after-mixer in the mold, and to prevent the gate finished surface from appearing on the surface of the molded product. That is.

[Means for solving problems]

The present invention provides a method for molding a reaction injection molded product having a core material, in which the core material is provided with an after-mixer section, the core material provided with the after-mixer section is installed in a mold, and the core material is disposed through the after-mixer section. The method is characterized in that a synthetic resin stock solution is injected into the cavity of the mold.

[Effect]

In the present invention, a synthetic resin stock solution such as polyurethane is injected into the cavity of the mold through an aftermixer section provided in the core material, aftermixing is performed within the cavity, and the aftermixer section is mixed with the core material. It is embedded within the molded product.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

21 is a mold, and this mold 21 consists of a lower mold 22 that moves up and down and an upper mold 23 that is fixed at a fixed position. A passage 24 opening to the back side of the molded product is provided at the upper center of the upper mold 23, and a mixing head 25 of a molding machine is mounted on the upper mold 23. At this time, the nozzle 25a of the mixing head 25 is fitted into the passage 24.

26 is a metal core material having an L-shaped cross section, for example, installed in the cavity 22a of the mold 21;
An after mixer section 27 made of lightweight and inexpensive synthetic resin is attached to the core material 26 with adhesive or the like. This after-mixer section 27 includes a box-shaped body 28
An opening 29 is formed on each side of the box-like body 28, and a flange 30 is formed at the top of the box-like body 28, and an opening 31 is formed in the center of the flange 30. An after mixer section 27 is fixed to the center of the core material 26.

Then, during molding, the core material 26 is placed on the cavity surface 23a of the upper mold 23, and the opening 31 at the top of the aftermixer section 27 is placed in the passage 23a of the upper mold 23.
Fix it so that it communicates with the mold, and close the mold.

Next, the nozzle 25a of the mixing head 25
From there, a synthetic resin stock solution such as polyurethane is injected into the after mixer section 27 under high pressure. The stock solution injected under high pressure collides with the bottom surface of the box-shaped body 28 of the after-mixer section 27 and bounces, and while achieving a mixing effect, it is filled into the cavity 22a from the side opening 29 and molded.

In this way, the core material 26 and the aftermixer section 27 are integrally embedded in the molded product.

In addition, as shown in Figure 3, during implementation,
Depending on the shape of the core material 26, the after mixer section 27 may be formed integrally with the core material 26.

〔Effect of the invention〕

According to the present invention, a synthetic resin stock solution such as polyurethane is injected into the cavity of the mold through the aftermixer section provided in the core material, aftermixing is performed within the cavity, and the aftermixer section is mixed into the core material. Since the gate is buried in the molded product together with the material, there is no waste of raw materials, and by selecting the raw material injection part, it is possible to prevent the gate finished surface from protruding to the surface side of the molded product.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a molded state showing an embodiment of the method of the present invention, Fig. 2 is a perspective view of a core material equipped with an after mixer section, Fig. 3 is a perspective view of another core material, and Fig. 4 is a perspective view of another core material. The figure is a perspective view showing a conventional method, and FIG. 5 is a sectional view of FIG. 4. 21... Mold, 22a... Cavity, 26...
...Core material, 27...After mixer section.

Claims (1)

[Scope of Claims] 1. A method for molding a reaction injection molded product having a core material, wherein the core material is provided with an after-mixer section, the core material provided with the after-mixer section is installed in a mold, and the after-mixer section is placed in a mold. A reaction injection molding method characterized in that a synthetic resin stock solution is injected into a cavity of the mold through a part.