JPS5828089B2 - Cold press molding method for automotive interior parts - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for cold press molding interior parts for automobiles, in which a boss portion for attachment to other parts can be simultaneously molded on the back surface of a molded product during cold press molding.

Automotive interior parts such as door trims, center pillars, rear corners, and rear parcels are made by pasting a skin material directly or through a cushioning material onto the surface of a core material that has been press-molded or hot-compression molded into the shape of the part. Conventionally, in order to attach these parts to the vehicle body, metal fittings are attached to the back side of these parts using rivets or caulking, and these parts are attached to the car body via the metal fittings.

However, when attaching these metal fittings to interior parts,
If the rivet head or riveting claw is exposed on the surface after the skin material has been pasted, the appearance is not only unsightly.
Installation locations are also limited.

In addition, when attaching the skin material after attaching the metal fittings to the core material, there is a problem that the metal fittings protrude onto the surface of the core material, which becomes an obstacle when attaching the core material and the skin material in the mold. arise.

On the other hand, if the core material is made of resin, the rivet heads and claws will not be visible on the surface, so if the core material is molded, the rivet heads and claws will not be exposed. It is possible to obtain a product that does not require complicated man-hours and has a good appearance.

However, in order to form such a complex curved surface, injection molding is generally used, but such a molding method is expensive and usually requires a resin core material. In order to reduce the cost of raw materials, a composite resin sheet is used, which is made by extruding a thermoplastic resin with a large amount of organic or inorganic filler such as wood flour. Press molding is the only method available, and in the case of press molding, it is extremely difficult to obtain molded products of multiple shapes by cold press molding.

That is, when press-molding a synthetic resin sheet, the hot press molding described above can obtain sufficient heat to improve resin flow, but the molding time is long and productivity is poor.

Conversely, in cold press molding, a semi-molten resin sheet is placed on the lower mold, and then the upper mold is engaged and pressed to form the mold. During one molding cycle, the resin flows along the mold. As the resin is flexibly deformed and solidified by removing heat from the mold, almost no resin flow occurs, and therefore the shape of the molded product is only formed into a curved surface within the range of the resin's flexible deformation. There are drawbacks.

This invention made it possible to form complex curved surfaces by cold press molding, which was previously impossible, by devising the shape of the mold and inserting a heat insulating material on the side opposite to the surface on which the complex curved surface is to be formed. It is something.

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

Figure 1 shows the main parts of the cold press mold used in the present invention, 1 is a lower mold, 2 is an upper mold, and the upper and lower molds 1 and 2 are not shown in their entirety, but the molded product It has a shaped surface.

A cylindrical recess 3 is formed at a predetermined position of the lower mold 1 in correspondence with the boss of the molded product to be obtained, and a convex built-up part 4 is formed around the entire periphery of the recess 3. Furthermore, the recessed portion 3 is formed deeper than the flat surface of the peripheral edge of the built-up portion 4.

Further, the surfaces of the upper mold 2 corresponding to the recessed portion 3 and the built-up portion 4 are smooth surfaces, so that when both molds 1 and 2 are engaged along their parting lines, a gap is formed between them. The cavity 5 is configured to be thin in the vicinity of the built-up portion 5a and thick in the other portion 5b, and the cavity thickness in the other portion 5b corresponds to the total thickness of the synthetic resin plate and the carpet, which will be described later.

Furthermore, the depth and inner diameter of the recess 3 correspond to the height and outer diameter of the boss portion described later, and are of a depth and diameter that are sufficient to hold a tapping screw screwed into the boss portion. is set to

Next, a description will be given of the order in which interior parts are cold press-molded using the press molding die configured as described above.

First, with both molds 1 and 2 open, the aforementioned synthetic resin plate 6 preheated to near its melting point is positioned and placed on the lower mold 1 (see Fig. 2a).

For example, if a polypropylene composite resin board obtained by extrusion molding by adding 50 parts of wood flour as a filler to 50 parts of polypropylene resin is used as the resin board 6, it is possible to use a polypropylene composite resin board obtained by extrusion molding. Although it is preheated to a temperature above ℃ and retains its shape, it is plasticized and in a semi-fluid state.

Next, the carpet 7 is positioned and placed on the resin plate 6 (see Figure 2b).

This carpet 7 functions as a heat insulating material between the resin plate 6 and the upper mold 2, and also digs into the surface of the resin plate 6 and is integrally attached thereto to form a skin.

Therefore, when the resin plate 6 is based on polypropylene, it is desirable to use polypropylene fibers or other blended products such as nylon or the like.

In addition, the thickness of this carpet 7 is the same as that of commercially available carpets, which provides a sufficient insulation effect, but thin carpets,
For example, a material as thick as cloth cannot provide a heat insulating effect.

Immediately after the above preparations are completed, both molds 1 and 2 are clamped, and the resin plate 6 and carpet 7 are pressed together.

At this time, the lower surface side of the resin plate 6 is rapidly deformed into the shape of the mold surface while rapidly losing heat by the lower mold 1, and is solidified, but the upper surface side is in a semi-fluid state due to the layer of carpet 7, and the cavity 5 However, since the built-up part 5a is thin, the resin plate 6 is recessed along the shape as shown by the arrow in Figure 2c, and the surplus resin corresponding to the recess flows into the lower mold 1. It enters the formed recess 3 and is solidified in that state.

On the other hand, the carpet 7 is formed by the fiber legs randomly digging into the surface of the resin board 6 due to the above-mentioned compression, and due to the anchoring effect and the affinity between the resin board 6 and the carpet 7 if they are the same or similar materials. In this state, the resin plate 6 is rapidly cooled by removing heat from both molds 1.degree.2, and at this cooled stage, both molds 1 and 2 are opened.

After demolding, the resin plate 6 is molded into a molded product shape as shown in FIG. 2d, and a boss portion 6a is formed on the back surface of the resin plate 6, and a carpet 7 is simultaneously attached to the surface of the resin plate 6 to form an interior component. get.

In addition, in order to attach a metal fitting to the boss part 6a, as shown in FIG.
1, and it becomes possible to attach it to the vehicle body.

As explained above, in the cold press molding method for automobile interior parts according to the present invention, the mold shape is configured such that the resin wall thickness at the peripheral edge of the mounting boss portion is thinner as described above. Moreover, by inserting a heat insulating material on the side opposite to the side where the boss is formed, the resin flow is improved, and as a result, complex curved surfaces can be formed by cold pressing, which was previously impossible. It made it possible.

Therefore, as described above, a boss portion for attaching a metal fitting can be arbitrarily formed on the back surface of the interior component according to the present invention, which has a great advantage in terms of product appearance and simplifying the number of steps.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of the main part of a cold press mold according to the present invention, Figs. 2a to 2d are sectional views of the main part showing the molding order of the invention, and Fig. 3 shows how the metal fittings are attached to the molded product. FIG. 3 is a cross-sectional view of main parts showing the installed state. 1...Lower mold, 2...Upper mold, 3...
・・Concavity, 4・・Building part, 6・・Synthetic resin plate, 6a・・Boss part, 6b・・・Screw pilot hole, 7・・・...Carpet (insulation material).

Claims (1)

[Claims] 1. A recess corresponding to a boss with a screw hole of a molded product to be molded is formed at a predetermined position in the lower mold of the upper and lower molds having mold surfaces formed in the shape of a molded product. At the same time, using upper and lower molds with a convex overlay on the periphery of the recess and smooth areas corresponding to the recess on the upper mold, a synthetic resin plate preheated to near the melting point is placed in the lower mold. At the same time, a heat insulating material is placed on the upper surface of this resin plate, and then the upper mold is engaged with the lower mold and pressed to press-form it into the shape of the molded product, and at the same time, it is molded into its predetermined position. Cold press molding method for automobile interior parts in which a boss part with a screw pilot hole is formed one step higher than the flat part of the product 0 2 The above-mentioned heat insulating material is made of a thick knitted product such as carpet, A method of cold press molding an interior part for an automobile according to claim 1, wherein the part is integrally attached to a surface.