JPH0247326B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of molding a molded article having an undercut portion using a cold-setting resin.

Conventionally, molded products with undercuts have been molded using room-temperature curable resins for reasons of mold cutting, using a mold divided into multiple parts, a resin mold, or a slide core. Molds and resin molds were expensive, molding operations were complicated, and molding was more likely to occur. Furthermore, there were other problems such as it was extremely difficult to apply colored coating to the inside of the undercut portion of the molded product.

The present invention has been made to solve the above problems, and one embodiment of the present invention will be described in detail below with reference to the drawings.

As shown in FIG. 1, the pressure inside the hollow chambers 1 and 2 is reduced by suction, and a suction action is applied to the surface of the core cavity 4 through the vent holes 5 and 5 of the vertically split master mold 3 in the form of a wooden or stone type. 4
A molded film 8 heated by a sheeter 7 to have increased extensibility is placed on the upper surface of the master mold 3 having an opening 6. As a result, as shown in FIG.
is adsorbed to the surface of Therefore, as shown in FIG. 3, a suction tube 9 is inserted into the core cavity 4 where the formed film 8 is adsorbed, and the average particle diameter is
After filling the particulate matter M with a thickness of 100μ, a sealing film 10 is placed over the upper surface of the master mold 3 and the particulate matter M, and the openings 6 are formed by joining the films 8 and 10 together with fusion bonding or adhesive tape. The core cavity 4 filled with the particulate matter M is then vacuumed and depressurized through the suction pipe 9 to solidify the particulate matter M, thereby molding the core mold C.

Next, as shown in FIG. 4, when the master mold 3 is opened left and right, the particulate matter M in the films 8 and 10 is removed.
A core mold C formed by solidifying into a predetermined shape can be taken out. The core mold C thus obtained is set in a molding mold 11 as shown in FIG. 5, and a product cavity 12 is defined by the molding mold 11 and the core mold C. A liquid room temperature curable resin is poured into the product cavity 12 to fill the product cavity 12 with the room temperature curable resin. After the room temperature curable resin is cured, the suction by the suction pipe 9 is stopped to collapse the solidified state of the core mold C, and the particulate matter M is discharged from the mold 11 to obtain a molded product having an undercut portion. be able to.

In addition, if the core cavity is deep and cannot be squeezed with a single film, the core mold can be made of multiple core molds C ₁ and C ₂ made in the same manner as described above.
They may be manufactured by bonding them together or by joining them with adhesive tape to integrate them (see Fig. 6).

Films 8 and 10 used in the above embodiments
Examples of the material include thermoplastic resins such as polyethylene, polypropylene, polystyrene, vinyl chloride, vinylidene chloride, polyamide, polycarbonate, ionomer, ethylene-vinyl acetate copolymer, polyolefin block polymer, synthetic rubber, and natural rubber. Molded products can be colored by using these materials as films 8 and 10 containing or coating coloring agents such as pigments, dyes, and metal foils, or containing or coating ultraviolet absorbers. . After the particulate matter M has been discharged, the films 8 and 10 are taken out while being attached to the molded product, but if the films 8 and 10 are not required for the molded product, they are cured at room temperature so that they can be peeled off. Consider the type of resin and film material, and
A mold release agent must be applied to the surface of the mold in advance.
On the other hand, if it is necessary to attach the specially treated films 8, 10 to the molded product in order to color the molded product, it is necessary to attach the films 8, 10 to the molded product in order to color the molded product. Film 8,10
It is sufficient to cut and remove the molded product and film 8,
When the adhesion with film 10 is poor, film 8,
10 requires treatment such as applying adhesive in advance. The particulate matter M includes inorganic particles such as metal powder, glass powder, sand, and other inorganic compound powders, and organic particles such as wood powder and plastic powder. The necessary properties of this particulate material are that it has good filling properties, and furthermore, when room-temperature curing resins generate heat during curing or require a certain degree of heating during molding, it must be able to withstand these temperatures sufficiently. It has heat resistance.
Further, the particle size of the particulate material may be about 10 μm to 3 mm, but care must be taken because the smoothness of the surface of the molded product is affected by the particle size. If the particle size is small, the smoothness of the surface of the molded product and the transferability of fine uneven patterns will be improved, but the particulate matter will be difficult to handle and will generate dust, which will worsen the environment. On the other hand, the opposite phenomenon will occur with coarse particles, and generally particles with a diameter of about 50 to 600 μm are preferable.

Note that the room temperature curable resin includes polyurethane, polyester, acrylic resin, epoxy resin, polyamide, furan resin, silicone resin, and modified resins thereof.

As is clear from the above description, the present invention molds a core mold by airtightly surrounding particulate matter with a film and solidifying the particulate matter by suctioning and reducing the pressure inside the film. Set in the mold to define the product cavity,
The product cavity is filled with liquid room-temperature curing resin, and after the resin hardens, the suction action of the suction tube is stopped to discharge particulate matter, which eliminates the need for expensive molds that are divided into multiple pieces. It is possible to accurately mold a molded product with an undercut using an inexpensive wooden mold or plaster mold using a cold-curing resin without using a resin mold or a slide core. By using it, molded products can be easily colored, and since there is no split surface in the core mold, excellent effects such as no burrs are produced on the molded products are achieved.

[Brief explanation of the drawing]

1 to 5 are longitudinal cross-sectional views showing the steps of one embodiment of the present invention, and FIG. 6 is a longitudinal cross-sectional view showing another embodiment of the core mold used in the present invention. 4: Core cavity, 6: Opening, 8: Film, 9: Suction tube, 10: Film, 11: Molding mold, 12: Product cavity.

Claims (1)

[Claims] 1 Adsorb a molded film onto the surface of the core cavity of the master mold, insert a suction pipe into the core cavity from an opening communicating with the core cavity, and charge particulate matter;
Subsequently, the opening is hermetically closed with a sealing film,
Using the suction tube, the inside surrounded by both films is sucked and depressurized to solidify the particulate matter to form a core mold, and after releasing the adsorption state of the molded film to the surface of the core cavity, the mold is released; The core mold is set in a molding mold to define a product cavity between the molding mold and the core mold, the product cavity is filled with a liquid room temperature curable resin, and after the room temperature curable resin is cured. . A method for molding a room-temperature curable resin, characterized in that suction by the suction tube is stopped to collapse the core mold and to discharge particulate matter from the mold.