JP2010221683A - Insert molding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique for insert molding, where a hollow-shaped part is set in a cavity, to conduct the molding so as not to cause deformation of the part by a simple mechanism. <P>SOLUTION: The method comprises the steps of: putting a hollow-shaped part 3 with an opening in the cavity 2 of a mold; filling a liquid into the hollow part of the hollow-shaped part 3; charging a molten material into the gap between the outer wall of the part and the inner wall of the cavity 2 in a state that the opening is sealed. Hence, a molded product with a high added value is obtained, which has a double-layer structure of different materials, and has a visual effect not available by conventional molding methods. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an injection-molded product obtained by molding integrally with another part inserted therein, and particularly relates to a method for molding an injection-molded product in which the another part has a shape having a hollow portion.

  Injection molding is widely used in various fields as a method of mainly molding thermoplastic polymer materials. In this molding method, one or both of the contact surfaces of a mold composed of two members, a fixed side and a movable side that can be opened and closed, are engraved with a recess called a cavity, to which the product shape is transferred. A molten polymer material is filled at a high pressure through a flow path called a sprue, a runner, and a gate in a state where the contact surface is in pressure contact, and a molded product is obtained.

  In this molding method, it is also possible to obtain a molded product in which the component and the material filled in the cavity are integrated by installing another component in an appropriate position in the cavity in advance. It is a feature. For example, there is a gear having a metal shaft and a plastic body. In addition, by this method, so-called two-color molded products in which plastics of two or more colors and materials are integrally molded are also produced.

  However, if the component installed inside the cavity has a hollow shape, when the molten material is filled in the cavity, the hollow component is crushed by the filling pressure, and it is difficult to obtain a required shape. This phenomenon is particularly prominent when the hollow part is a separately molded plastic body.

  As a means for coping with such a problem, Patent Document 1 discloses that a hollow part installed in a cavity is deformed by performing a process of closing a mold and a process of press-fusing molten material into the cavity in parallel. A technique for preventing the above is disclosed. However, this method has a problem that the structure of the mold becomes complicated and increases the manufacturing cost of the product, and the difficulty of setting molding conditions increases.

  JP 2004-268456 A

  Therefore, the subject of this invention is providing the technique which performs insert molding which installed the hollow-shaped components in the cavity by a simple mechanism so that the said components may not deform | transform.

  In general, the compressibility of a liquid when a pressure is applied is small enough to be ignored when compared with a gas. Further, for example, a hollow product such as a bottle has an opening as a matter of course, and it is very easy to inject and discharge liquid. Therefore, if the hollow part of such a part is placed in a mold in a state where the liquid is filled and sealed and insert molding is performed, it is considered that the hollow part is less deformed by the filling pressure of the molten material.

  Based on such knowledge, the present invention has been made as a result of studying a method for sealing an opening of a hollow-shaped component installed inside a mold and a mold structure suitable for the method.

  That is, the present invention is a molded article having an opening and at least a hollow shape having a two-layer structure.

  Further, the present invention provides a hollow part having an opening in a cavity of a mold, a liquid is sealed in the hollow part of the part, and the outer wall of the part and the inner wall of the cavity are sealed in the opening. It is the molding method of the above-mentioned molded body characterized by filling a molten material in the gap between the two.

  According to the molding method of the present invention, so-called two-color molding is possible in a hollow shape such as a bottle, for example, so that a molded body that exhibits a visual effect that is impossible with the conventional method is obtained. Especially when transparent materials with different refractive indexes are combined, the light from the outside is totally reflected or partially transmitted by the interface of different materials depending on the viewing angle, giving a special visual effect. .

  Also, a combination of transparent and opaque materials can provide a visual effect different from the above, and can improve the added value of the molded body. For this reason, for example, it can be used for products that need to give a high-class feeling to containers, such as cosmetics and perfumes.

  The figure which showed the cross section of the metal mold | die in the example which applied the molding method which concerns on this invention to injection molding.   The figure which shows the example of the bottle shape | molded by the shaping | molding method which concerns on this invention.

  The following embodiments of the present invention will be described with reference to specific drawings.

  FIG. 1 is an example in which a molding method according to the present invention is applied to injection molding, and is a view showing a cross section of a mold. In FIG. 1, 1 is a movable side mold, 2 is a cavity, 3 is a hollow part, 4 is an R-shaped part, 5 is a slide core, 6 is an O-ring, 7 is an opening sealing member, and 8 is a fixed side mold. It is a type.

  In this example, a thermoplastic polymer material is prepared in advance by blow molding or injection molding as the hollow part 3. The inside of the hollow part 3 is filled with a liquid, the opening sealing member 7 is attached to the opening of the hollow part 3 to seal the opening, and the fixed part 8 is fitted into a predetermined position.

  As the liquid used here, various oils and water can be used. Depending on the fluidity of the material used for molding, the material may be filled at a temperature of 200 ° C. or higher, and the mold temperature may be set higher correspondingly. In this case, it is necessary to use a liquid having a high boiling point such as silicon oil. However, as the liquid, water is the easiest to handle, so it is desirable to use a material with as high a fluidity as possible.

  Next, the slide core 5 and the movable mold 1 are operated to obtain the state shown in FIG. 1, and the cavity 2 is filled with a molten polymer material plasticized by a cylinder (not shown) of a molding machine. Thereafter, the movable mold 1 and the slide core 5 are opened, and the molded product is taken out. In injection molding, in order to prevent deformation of a molded product, the molten material filled in the cavity is generally cooled to some extent and solidified, and then the mold is opened and the molded product is taken out. However, in the molding method of the present invention, a tube having an on-off valve is connected to the opening sealing member 7 so that after the material filling into the cavity is completed, the sealed liquid is cooled. This can contribute to shortening the molding cycle and improving the dimensional accuracy of the molded product.

  FIG. 2 is a view showing an example of a bottle formed by the forming method according to the present invention. In FIG. 2, 9 is a hollow-shaped part set in the fixed mold 8 during molding, that is, a primary molded product, and 10 is a part molded by filling the cavity 2, that is, a secondary molded product.

  Thus, according to the present invention, a hollow molded product having a two-layer structure of different materials or the same material can be obtained. Thus, a molded product having a visual effect that cannot be obtained by the conventional molding method and having a high added value can be obtained.

  The present invention is not limited to the above-described embodiments, and various thermosetting polymers can be used as primary molded articles such as deformations and modifications that can be conceived by those having ordinary knowledge in the technical field. Needless to say, the present invention is also included in the present invention.

DESCRIPTION OF SYMBOLS 1 Movable side metal mold | die 2 Cavity 3 Hollow shape part 4 R shape part 5 Slide core 6 O-ring 7 Opening part sealing member 8 Fixed side metal mold 9 Primary molded article 10 Secondary molded article

Claims (3)

  A molded article having an opening and at least a hollow shape having a two-layer structure.   A hollow part having an opening is placed in a cavity of a mold, a liquid is sealed in the hollow part of the part, and the opening is sealed, and in a gap between the outer wall of the part and the inner wall of the cavity, The method for forming a molded body according to claim 1, wherein the molten material is filled.   The tubular member is attached to a member for sealing the opening, and after the filling of the material into the cavity is completed, the liquid sealed in the hollow portion of the component is replaced. The molding method of the molded object according to claim 2.

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