JPS62152713A - Manufacture of resin molded body with shape developing undercuts - Google Patents

Abstract

PURPOSE:To make it possible to easily mold a resin part with undercut shapes by a method wherein a molded part and a soluble member are integrally removed from molds after the curing of resin and, after that, the soluble member is removed by being dissolved. CONSTITUTION:A molded body 1 is molded by pouring resin in a cavity consisting of a soluble member 2 supported by a core pin 10, a movable retainer plate 8, a retainer plate 9 and an ejector pin 11. After the curing of the resin, a molded body 1 and a soluble member 2, both of which are made into an integral body, are removed from the molds and, after that, immersed in water or water is flowed through a hole 6 made by the core pin 10 so as to remove the soluble member 2 through dissolution with water in order to finally obtain a molded body 1. As an example of the soluble member 2, neutral polysaccharide consisting of regularly alpha-16 bonded maltotriose is employed. Thus, the restriction of the shape of undercut on product design is removed and the molding with a low cost and highly durable mold is made possible.

Description

Detailed Description of the Invention A. Purpose of the Invention [Field of Industrial Application] The uninvented object is a resin molding having a shape that is undercut in the direction of mold removal when resin is injected into a mold and molded. Concerning a method of manufacturing a body.

[Conventional technology]

In order to manufacture a resin molded body having a shape that is undercut in the drawing direction of conventional molds, the molded product is forcibly pulled out or a slide mechanism is inserted into the mold.

[Problem that the invention seeks to solve]

However, in the former case, the molded product has a large mold release resistance, which may cause deformation and deterioration, and there are considerable restrictions on the resin used and the undercut shape. In the latter case, the mold structure becomes complicated, which not only makes the mold larger than necessary, but also poses a problem in the durability of the sliding part, and the shape of the anchor in the part where the sliding mechanism cannot be inserted. Product design constraints, such as the inability to do so, were also a problem.

An object of the present invention is to provide a method for manufacturing a resin molded article that eliminates each of the above-mentioned restrictions.

Summary: Structure of the Invention [Means for Solving the Problems] The present invention provides a method for manufacturing a resin molded article having an anchor/cart shape with respect to the direction of mold removal. The part is made of a soluble material in advance, and 4M fat is injected into the mold cavity.
After the resin has hardened, the molded body and the soluble member are taken out of the mold as one body, and then the soluble member is dissolved and removed. This is a method for manufacturing a resin molded body having an undercut shape.

[For production]

The part of the member forming the mold cavity where the undercut shape (biting part) is to be formed is made of a soluble material, and after resin molding, it is removed from the mold together with the molded body, and the soluble material is dissolved and removed. The mold structure is simplified and even complex product shapes can be easily molded.

〔Example〕

3 to 5 are explanatory diagrams of the method of the present invention when molding the resin molded article shown in FIG. 3.

In the figure, 1 is a resin molded body, 2 is a soluble member forming a part of the mold, 3 is a notch (undercut), 4 is a threaded part, 5 is a screw hole, 6 is a hole drilled in the soluble member 2, 7 is a resin gate, 8 is a movable side template, 9 is a fixed side template, 10 is a core pin,
11 is an ejector bin.

As shown in FIG. 4, the molded body 1 is screwed together with the inner tube 13 to constitute, for example, a helicoid for a camera.

14 is an intermediate member for absorbing backlash between l@13.

As shown in FIG. 1, a resin is injected into a cavity consisting of a soluble member 2 supported by a core pin 10, a movable mold plate 8, a fixed mold plate 9, and an ejector bin 11 to form a molded body l.

After the resin has hardened, the molded body l and the soluble member 2 are taken out of the mold as shown in FIG. By dissolving and removing the soluble member 2, the molded body 1 shown in FIG. 3 is finally obtained.

As an example of the above-mentioned soluble member 2, a neutral polysaccharide in which maltotriose is regularly bonded with α-16 is used. After being formed as a structural member, it has heat resistance and strength that can be used in injection molding, etc., and at the same time, it has water-soluble properties, so it can be immersed in an aqueous solution in an aqueous state. It can be dissolved and removed in a short time.

5 to 7 show other embodiments, which are difficult to handle with conventional undercut processing mechanisms.

FIG. 5 shows an undercut 35 on the inside of the box-shaped molded body 1 as shown in FIG.

FIG. 6 shows a plate part l having a catch shape 36 as shown in FIG. 6(A).

FIG. 7 shows an example of the molded body 1 having a straight or reversely tapered deep hole 37 shown in FIG. 7A.

C. As explained in detail, according to the present invention, the molded article shown in FIG. The molded body shown in FIG. 5 (A) has a straight elongated hole or small diameter reverse tapered hole (FIG. 7 (A)), which was difficult to handle with the conventional undercut processing mechanism, or A molded body having a hollow undercut shape (Fig. 6 (A)
) can also be formed, allowing for free undercut shapes in product design.

Furthermore, since the mold structure is simple, molding can be performed using inexpensive and highly durable molds.

[Brief explanation of drawings]

Figures 1 and 5 to 7 are cross-sectional views of molds of different embodiments for carrying out the method of the present invention, Figure fJ12 is a cross-sectional view of the integral molded body and soluble member, and Figures 3 to 5 Figures (A) to 7(A) are cross-sectional views of molded products, and Figure 54 is a cross-sectional view of a helicoid using the molded product shown in Figure 3. l is a resin molded body, 2 is a soluble member, 3, 35, 36, 3
7 is an undercut, 4 is a threaded part, 5 is a screw hole, 6 is a hole in the resin member 2, 7 is a resin gate, 8 is a movable side template, 9 is a fixed side template, IO is a core pin, 11 is an ejector bin ,1
3 is an inner cylinder, 14 is an intermediate member, and 15 is a cavity core.

Claims (1)

[Claims] (1) In the production of a resin molded body having an undercut shape in the direction of mold removal, at least a part of the member forming the mold cavity is made of a soluble material in advance, and a resin is injected into the mold cavity. A method for manufacturing a resin molded body having an undercut shape, comprising: taking out the molded body and the soluble member as one body after the resin has been cured, and then dissolving and removing the soluble member.