JP3355756B2 - Core injection molding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection molding method, and more particularly, to a table in which a core material is arranged in a mold and integrally joined with the core material.
The present invention relates to an integral molding method for forming a skin .

[0002]

2. Description of the Related Art For example, as a method of manufacturing an armrest of an automobile, a separately formed hard core material is placed in a mold, and a skin such as soft vinyl chloride is injection-molded on the surface of the core material. It has been known. In this case, it is desirable that the core material be in close contact with the surface of one of the molds, but the core material may rise from the mold depending on the shape. In particular, the terminal portion of the core material is easily lifted, and depending on the shape, the core material may be further lifted by receiving pressure from the molding material. In particular, if the degree of lifting of the core material is large, such as when the thickness of the skin is thin, the core is exposed on the surface of the skin and becomes a defective product.

In order to prevent the core material from being exposed, a method of increasing the thickness of the skin body, providing an undercut shape to the core material, and pressing the core material against a mold by a slide mechanism or the like has been adopted. ing.

[0004]

However, in the method of increasing the thickness of the skin body, the position where the core material floats is often indefinite, so that the entire skin body has to be thickened. Unnecessary parts are thickened, resulting in excessive quality, resulting in cost problems. Further, in the method of providing a slide mechanism or the like in the mold, the structure of the mold is complicated, and there is still a problem in cost.

The present invention has been made in view of such circumstances, and has as its object to prevent inexpensive lifting of a core material from a mold surface.

[0006]

According to the present invention, there is provided a core material-integrated injection molding method which comprises disposing a core material on a surface of one of the split dies, and forming a mold surface of the other mold with a surface of the core material. In a core material integral injection molding method of forming a skin integrally covering the surface of the core material by injecting a molding material between the core material and the surface of the core material facing the mold surface of the other mold, a concave portion is partially formed. Sticky, concave
The part where the cavity is larger than other parts
The core material is pressed against one of the molds by the pressure of the molding material flowing preferentially through the recess.

[0007]

[0008]

In the molding method of the present invention , a core material is first placed on the surface of one of the split molds, and the molding material is injected between the mold surface of the other mold and the core material surface. Here, in the present invention, the concave portion is partially formed on the surface of the core material. Therefore, the space between the cavities becomes larger in the portion where the concave portion exists, and the molding material flows preferentially in the concave portion. As a result, the pressure from the molding material largely acts on the concave portion of the core material, so that the core material is pressed by at least one of the molds at least at the concave portion and closely adheres to the surface of the one mold. Therefore, the core material is prevented from rising from the surface of the one mold.

[0009]

[0010]

The present invention will be specifically described below with reference to examples. In the following embodiment, the present invention is applied to the manufacture of a door armrest of an automobile. (Embodiment 1) FIG. 1 is a sectional view of a mold immediately after injection molding. This mold comprises an upper mold 1 and a lower mold 2, a core material 3 is arranged on the surface of the lower mold 2, and a molding cavity 10 for forming a skin 4 between the surface of the core material 3 and the upper mold 1 is formed. Have been.

As shown in a perspective view of FIG. 2, the core member 3 has a substantially box-like shape, and has grooves 30 and 31 formed on the surface thereof in the longitudinal direction and in the direction crossing the longitudinal direction. In the present embodiment, first, the core material 3 is arranged on the lower mold 2 and is clamped to the upper mold 1. A molten resin of a soft vinyl chloride resin is supplied from a gate (not shown) to the molding cavity 10.
It is injected inside. At this time, in the molding cavity 10, since the cavity interval between the grooves 30 and 31 is the largest,
The molten resin flows preferentially through the cavities in the grooves 30 and 31.

Then, the injection pressure of the molten resin is transmitted to the portions of the grooves 30 and 31 of the core material 3, and the core material 3 is pressed against the lower mold 2 at least at that portion. Therefore, the core material 3 is in close contact with the surface of the lower mold 2 and is prevented from rising from the lower mold 2. Then, the entire molding cavity 10 is filled with the molten resin and cooled and solidified, whereby an armrest having the skin 4 is obtained.

That is, according to the molding method of the present embodiment, although the thickness of the skin 4 is slightly increased at the grooves 30 and 31, the lifting of the core material 3 is prevented.
No defective products are produced even if the thickness of the portions other than 0 and 31 is reduced. Therefore, the volume of the skin 4 can be reduced as a whole as compared with the conventional case, and the cost can be reduced. Further, since a slide mechanism for pressing the core material and the like as in the related art is not required, the cost of the mold can be reduced.

[0014]

[0015]

[0016]

[0017]

[0018]

In other words, according to the core material integral injection molding method of the present invention, since the core material is prevented from being lifted, no defective product is produced even if the thickness of the portion other than the concave portion is reduced.
Therefore, although the thickness of the molded skin is increased in the concave portion, the volume of the molded skin can be reduced as a whole as compared with the related art, and the cost can be reduced.
Further, since a slide mechanism for pressing the core material and the like as in the related art is not required, the cost of the mold can be reduced.

Further, according to the core material integral injection molding method of the second invention, it is possible to reliably prevent the terminal portion from being lifted up only by reducing the interval between the cavities on the back surface side of the terminal portion of the core material, which is extremely advantageous in terms of cost. is there.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a molding die used in one embodiment of the present invention after a molding step.

FIG. 2 is a perspective view of a core used in one embodiment of the present invention.

[Explanation of symbols]

1: Upper mold 2: Lower mold
3: core material 4: skin 10: cavity 30, 3
1: groove (recess) 32: terminal

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B29C 45/14

Claims (2)

(57) [Claims] 1. A core material is arranged on the surface of one of the split molds, and a molding material is injected between the mold surface of the other mold and the surface of the core material to integrally cover the surface of the core material. In a core material integral injection molding method for forming a skin, the surface of the core material facing the mold surface of the other mold has a concave portion partially, and the portion where the concave portion exists has a cavity between the cavity.
A core material integral injection molding method, wherein a gap is larger than other portions, and the core material is pressed against the one mold by a pressure of a molding material flowing preferentially through the concave portion. 2. A core material is arranged on the surface of one of the split molds.
Inject molding material between the mold surface of the other mold and the core material surface.
Core material forming a skin integrally covering the surface of the core material
In the injection molding method, the surface of the core material facing the mold surface of the other mold is partially
With a groove, the pressure of the molding material flowing preferentially through the groove
The core material is pressed against the one mold.
Body injection molding method.