JPH0686077B2 - Multi-layer molding method for thermoplastic synthetic resin materials - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION 3-1. Object of the Invention 3-1-1. Industrial Application Field The present invention relates to a method for forming a multilayered thermoplastic synthetic resin material.

3-1-2. Conventional Technology Conventionally, in order to laminate and composite a thermoplastic synthetic resin material into two layers, first, the first layer is injection-molded, and then the second layer is injection-molded. The method of dividing the resin material into two parts was used, but in this conventional method, the degree of shrinkage differs when different types of synthetic resin materials are used, which causes deformation of the molded product and dimensional deviation. However, there is a technical unavoidable problem that a difference in shrinkage occurs due to a difference in molding time even when the same kind of resin material is used.

That is, when the primary resin material is injected and cooled, the mold opens, and when this mold is closed by another cavity, the secondary resin material is injected. The primary cause was that the primary resin material was already approximately 80% shrunk at the time the material was injected.

3-1-3. Problem to be Solved by the Invention The present invention provides a method for favorably performing molding for composite lamination of thermoplastic synthetic resin materials, which has been difficult in the past, without causing deformation in the whole. The purpose is to solve the above technical problems.

3-2. Structure of the Invention 3-2-1. Means for Solving the Problem The present invention is to inject a primary synthetic resin material toward a lower mold die having a recessed row formed at an appropriate interval on the upper surface. Then, mold the primary synthetic resin body with concave rows formed on the lower side surface, then inject the secondary synthetic resin material on the flat upper surface of the primary synthetic resin body to mold the secondary synthetic resin body and integrally It is a multi-layer molding method that is formed by joining.

3-2-2. Example (1) The die (2) of the lower die (1) is constructed according to the form of the object to be formed, but the upper surface of the die (2) is convexly spaced in the vertical and horizontal directions at appropriate intervals. Form a row (3).

After lowering the primary cavity (4) of the upper die to the lower die (1), the primary synthetic resin material is injected into the space on the upper surface of the die (2) to form the primary synthetic resin body (5). Form.

(See FIG. 1) On the lower side surface of the primary synthetic resin body (5) obtained by injection molding of this primary synthetic resin material, a groove (8) having a trapezoidal cross section in the vertical and horizontal directions by the raised row (3). Therefore, the material thickness of the upper side surface portion of the synthetic resin body (5) becomes thin.

The condition when the primary synthetic resin material is molded is fixed as it is on the die surface of the lower mold, so even if it tries to shrink due to cooling, it is forcibly blocked by the convex row on the lower mold die surface. It cannot be shrunk and is still stretched.

(2) After the primary synthetic resin body (5) has cooled for a predetermined time, the primary cavity (4) is pulled up. (See FIG. 2) (3) Next, the secondary cavity (6) descends toward the primary synthetic resin body (5) on the die (2) of the lower mold (1), and the secondary synthetic resin The material is injected onto the flat upper surface of the primary synthetic resin body (5) to form the secondary synthetic resin body (7). (Refer to Fig. 3 and Fig. 4) Then, the shrinkage starts again and the deformation is about to occur. Since it is performed only within the divided inner portion and the internal stress generated due to the difference in shrinkage is absorbed, it is possible to prevent the deformation of the entire multilayer synthetic resin body from occurring.

(4) When the secondary synthetic resin body (7) is cooled and integrated with the primary synthetic resin body (5) after a lapse of a predetermined time, the secondary cavity is pulled up and the combined multi-layer synthetic resin body is removed from the mold. Take it out. (Refer to FIG. 5) 3-3. Effect of the Invention Since the present invention is a method of molding by the above steps,
It has become possible to manufacture a multi-layer member made of a plastic synthetic resin of extremely good quality, in which the molded product is hardly deformed or the dimensions are not changed, and the effect is great.

[Brief description of drawings]

The drawings show an embodiment of the present invention, FIG. 1 is a front sectional view of a mold at the time of primary molding, FIG.
Fig. 4 is a front sectional view before secondary molding, Fig. 4 is a front sectional view of a mold at the time of molding of the same, Fig. 5 is a front sectional view of a molded product, and Fig. 6 is an enlarged perspective view of a main part of the molded product. FIG. 7 is an enlarged front sectional view of the main part of the same.

Claims (1)

[Claims] Claim: What is claimed is: 1. A primary synthetic resin material having a concave row formed on the lower side surface is formed by injecting a primary synthetic resin material toward a lower mold die having concave rows arranged on the upper surface at appropriate intervals. A multi-layer molding method for a thermoplastic synthetic resin material, in which a secondary synthetic resin material is injected onto the flat upper surface of the primary synthetic resin material to mold the secondary synthetic resin material and integrally joined.