JPS5822325B2 - Press molding method for automotive interior parts - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a press molding method for automobile interior parts,
In particular, the bracket can be integrally inserted into the back surface of the molded product during press molding.

For example, interior parts for automobiles such as IJs (doors) are made by bonding a skin material directly or through a pad material to the surface of a core material formed in the shape of the part.

In addition, metal fittings such as brackets are attached to the back of the core material at the locations where interior parts are attached to the vehicle body and parts such as door handles. In the case of punched board products such as the above, this was done by caulking, etc., but this required a large amount of man-hours, and the appearance of the product was poor because the rivets and locking claws were exposed on the surface side. However, there were drawbacks such as noticeable unevenness in that area.

On the other hand, insert molding is possible when the core material is made of resin, but although this insert molding can be applied to injection molding, it is said that insert molding cannot be performed by press molding.

By the way, the material selected for the core material is a polyolefin resin such as polypropylene with a large amount of organic or inorganic filler such as wood flour (pulverized waste wood such as wood chips) in order to make it cheap and strong. However, such materials are unsuitable as injection molding materials due to problems such as flow, and press molding is most suitable.

In addition, in order to perform press molding, the material is preheated to a temperature above its softening point and the mold is clamped, but in this case, the molding is done by plastic deformation of the resin, and there is almost no resin flow, so inserts cannot be made. On the other hand, in order to make the insert possible, it is necessary to increase the resin temperature and heat the mold.
Because the molding cycle becomes extremely long and productivity decreases,
It was not practical.

The present invention was made based on the above background, and provides a method for press molding interior parts for automobiles, which enables inserts to be formed by press molding by improving the shape of the mold and the shape of the bracket. be.

An embodiment of the present invention will be described in detail below with reference to the drawings.

Fig. 1 shows the main parts of the press molding die used in this invention, 1 is the lower die, 2 is the upper die, and although the entire upper and lower dies 1 and 2 are omitted, the shape of the molded product is It has a mold surface of

A recess 3 is formed at a predetermined position on the lower mold 1 to fit the convex shape of the bracket, which will be described later, and a plurality of blind holes 4 are formed around the recess 3. has been done.

Further, the surface of the upper mold 2 corresponding to the recess 3 and the blind hole 4 is formed into a smooth surface or a gently curved surface parallel to the curved surface of the lower mold 1, so that both molds 1 and 2 are connected to their parting surface. When engaged along the two sides, the thickness of the cavity 5 formed between the two is set to be equal to or slightly thinner than the thickness of the resin plate, which will be described later.

Moreover, what is shown in FIG. 2 shows the above-mentioned bracket 6, and this bracket 6 has screw holes 7 for fitting bolts on the top surface.
It consists of a convex bracket main body 8 with an opening, and a mounting base 9 extending integrally around the bottom periphery of the bracket main body 8. The contact hole 10 is opened, and
The diameter of this locking hole 10 is set to be smaller than the diameter of the blind hole 4.

Next, a description will be given of the order in which the bracket 6 is inserted at the same time as the interior parts are press-molded using the press-molding die configured as described above.

First, when both molds 1 and 2 are opened, the bracket 6 is fitted into the recess 3 of the lower mold 1 to align the locking hole 10 of the mounting base 9 with the blind hole 4, and then The aforementioned synthetic resin plate 11 preheated to near its melting point is positioned and placed on the lower mold 1 (see Fig. 3a).

As this resin plate 11, for example, polypropylene resin 50 is used.
When using a propylene composite resin liquid obtained by extrusion molding by adding 50 parts of wood flour as a filler to 50 parts of wood powder, it is preheated to 200°C or higher, which is close to its melting point (2400°C), and the shape retention is However, at least its surface is plasticized and in a semi-fluid state.

The material of the resin plate may be a thermoplastic resin other than those mentioned above, but it should be made of a material that retains its shape when heated to at least near its melting point, and the heat treatment should be such that the entire part is softened and the surface is semi-finished. What is necessary is to perform a process that brings it into a fluid state.

Immediately after the above preparatory operations are completed, both molds 1 and 2 are clamped to press the resin plate 11.

At this time, the resin plate 11 is compressed into the mold surface shape between the two molds 1 and 2, plastically deformed and formed into a molded product shape, and forms the core material of the interior parts. The heat is removed and the resin cools and solidifies, but at the mounting position of the bracket 6, the resin bites into the locking hole 10 and the inner bottom surface of the bracket body 8, as shown in FIG. Since the resin is smaller than the diameter of the blind hole 4, the semi-fluid resin bitten into the locking hole 10 swells at the lower surface of the locking hole 10, and is cooled and solidified in this state.

After demolding, the resin plate 11 becomes a molded product as shown in FIG.
0 is filled with resin as if it were caulked,
As a result, the bracket 6 is integrally fixed to the back surface of the molded product.

Furthermore, if a thick knitted product such as a carpet is selected as the skin material to be adhered to the surface of the core material formed in this way, the mold can be tightened after laying it on the resin plate. The fiber legs bite into the surface of the resin plate in a molten state, allowing the skin to be attached at the same time as press molding, further simplifying the process.

Further, since these thick knitted products have a function as a heat insulating material, the resin flows well, and this has the advantage that the bracket can be fixed even more firmly.

As explained above, in the press-molding method for automobile interior parts according to the present invention, recesses corresponding to the shape of the protrusions of the bracket are carved at predetermined positions, and blind holes are carved around the four parts. Using the lower mold, and as a bracket,
a convex bracket body that fits into the recess; a mounting base integrally formed on the periphery of the bracket body;
An opening is made in this mounting base corresponding to the blind hole in the lower mold,
By using a bracket with a locking hole smaller in diameter than the diameter of the blind hole, the resin bulges into the locking hole during press molding, making it possible to mold the bracket at the same time as press molding, as if it were caulked. This makes it possible to use inserts in press molding as well as in injection molding.

Therefore, on the back side of the interior parts according to the present invention, brackets can be arbitrarily fixed to the vehicle body mounting points and parts mounting points at the same time as molding, which is extremely beneficial in terms of simplifying the number of man-hours, and the rivets. Since the head and locking claws are not exposed on the product surface, it has the advantage of improving the appearance of the product.

[Brief explanation of drawings]

FIG. 1 is a sectional view of the main parts of a press molding die according to the present invention,
FIG. 2 is a perspective view of the bracket, and FIGS. 3a to 3c are sectional views of essential parts showing the molding sequence of the present invention. 1...Lower mold, 2...Upper mold, 3...
... recess, 4 ... blind hole, 6 ... bracket, 8 ... bracket body, 9 ... ...
Mounting base, 10... Locking hole, 11...
・Synthetic resin board.

Claims (1)

[Claims] 1 Using a press molding die consisting of a lower mold in which four parts corresponding to the shape of the convex part of the bracket are installed at predetermined positions and blind holes are carved around these four parts, and an upper mold that engages with this lower mold. In this method, the bracket to be engaged with the recess of the lower mold includes a convex bracket body, a mounting base integrally formed around the periphery of the bracket body, and a mounting base on which the lower mold is molded. It consists of a locking hole that is opened corresponding to the blind hole and has a diameter smaller than the diameter of the blind hole, and after this bracket is fitted into the recess of the lower mold, at least the surface is preheated to near the melting point and in that state. Place the synthetic resin plate whose shape is retained on the lower die, and then press the upper die onto the lower die to press the resin plate into the shape of the molded product.At the same time, place the mounting base of the bracket on the resin plate. Dig into the surface,
A method for press-molding an interior part for an automobile, in which the mounting base is fixed in a semi-buried state and the mounting base is prevented from coming off by the swelling of the protruding end of the resin extruded into the blind hole through the locking hole.