JPH0134154B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a compressed air molding method suitable for manufacturing vehicle door inner trims, etc. using a sheet-like laminated material having a foamed resin layer as an intermediate layer. It is.

BACKGROUND TECHNOLOGY In general, when manufacturing door inner trims for vehicles, etc., a base material made of thermoplastic resin or the like and a covering material are laminated together with a foamed resin layer serving as a cushion material interposed between the covering material. These are shaped in advance in a separate process to match the shape of the door inner trim, and then bonded to each other with a foamed resin layer in the middle. However, in this case, each material is formed separately and bonded to each other, which requires a large number of manufacturing steps and is time-consuming, resulting in extremely low manufacturing efficiency.

In order to eliminate this drawback, the base material and the skin material may be laminated and bonded in advance with a foamed resin layer interposed therebetween, and the sheet-like laminated material may be formed into a desired shape in one step.

Conventionally, press molding or vacuum forming is usually applied to form this type of sheet-like product using a metal mold. However, when directly press-molding a laminated material having a foamed resin layer as an intermediate layer, the laminated material is press-molded in a heated and softened state.
Since the foamed resin layer of the intermediate layer is crushed and the cushioning performance is deteriorated, it cannot be used in principle. In addition, in the case of vacuum forming, when applying vacuum suction (see Figure 1 a), the foamed resin layer c between the skin material a and the base material b expands greatly due to the vacuum suction, and the mold M is relatively thin. There is a possibility that the base material b cannot be formed into a desired shape because of separation at a deep recess (see FIG. 1b). On the other hand, when applying vacuum male pulling (see Figure 2 a), the base material b
To apply a vacuum by applying the side to the male mold, remove the skin material a.
However, there is a drawback that the corner from the base of the uneven shape to the concave part cannot be shaped sharply and becomes rounded (see Fig. 2b). In addition to press forming or vacuum forming, air pressure forming is used, in which the material to be formed is placed in the mold and clamped, and then air pressure is applied from one side of the mold to press the material to the other side of the mold. It is also possible to do so (Japanese Unexamined Patent Publication No. 126266/1983). However, when this pressure forming is applied solely to a relatively thick laminate consisting of a skin material, cushion material, base material, etc., it is difficult to shape the material to be formed into a deeply uneven shape.

DISCLOSURE OF THE INVENTION The present invention provides a molding method capable of molding a laminated material in which a skin material and a base material are integrally bonded with a foamed resin layer interposed therebetween into a desired shape.
With the goal.

That is, in the mold forming method according to the present invention,
The laminated material is heated and softened and placed on the shaping surface of the mold, and the molded part is pre-pressed with a plug press die that approximately matches the shaping surface of the mold, and the molded part is airtight with a box-shaped top lid. After surrounding the mold, air pressure above atmospheric pressure is applied to the mold via a plug-pressing mold.
The air pressure is used to press the laminated material from the plug press die onto the shaping surface of the die.

Embodiment This will be explained below based on the embodiment shown in FIGS. 3 to 6.

The illustrated embodiment is for manufacturing a door inner trim for a vehicle, and its materials include skin material a,
A sheet-like laminate material is used, which is formed of at least three layers consisting of a base material b and a foamed resin layer c as an intermediate layer (see FIG. 3). The skin material a includes PVC,
Sheet materials such as TPE, other thermoplastics or fabrics can be used. For the base material b, a thermoplastic material formed into a board shape can be used, and a mixed material of PP and wood flour is particularly suitable because it is compatible with recycling and is lightweight. For the foamed resin layer c, a polyolefin foam or the like can be used, and in order to form it as a cushion layer, a foam with a foaming ratio of 3 to 50 times can be used. In particular, foams with a foaming ratio of about 15 to 20 times are preferred from the standpoint of providing both strength and cushioning properties. In laminating these layers, the foamed resin layer c is attached to the skin material a at the same time as foam molding and is continuously fed out, and the foamed resin layer c, which is heated to about 180°C, is attached to the base material b. Pressure bonding allows the three layers to be bonded together at the same time (see Figure 4). In addition, this laminated material has a skin material a.
0.2~0.6t, base material b 0.8~2.5t, foam layer c 2.0~
It is best to form it with a material ratio of about 4.0t.

This sheet-like laminated material is cut into an area corresponding to the size of the vehicle door inner trim, and then
Soften by heating. The heating and softening treatment can be carried out by holding the periphery of the laminated material with a clamp C and heating it with a heater H (see Figure 5a), and this temperature is 250°C.
A temperature of ~350°C is appropriate. Next, the heat-softened laminated material is placed on the shaped surface of the mold M (see FIG. 5b). This mold M is a female mold, and the female mold is arranged with the skin material a side of the laminated material facing the shaped surface of the mold M. At this time, it is preferable to clamp the periphery of the laminated material with clamps C so that it does not sag into the recess of the female mold M so as to stretch it. For the laminated material, an upper lid F is used, which is equipped with a plug-pushing mold P on the inside, which has a shape that roughly corresponds to the shaped surface of the mold M, which has a relatively large depth of unevenness (see Fig. 5b). The upper lid F is moved downward with a cylinder or the like, and the flange portion of the upper lid F is strongly pressed against the laminated material on the mold M while prepressing the laminated material with the plug press die P, thereby forming a periphery corresponding to the molded portion of the laminated material. Keep airtight.
Once the shaped portion of the laminated material is maintained in an airtight state with the upper lid F, air pressure higher than atmospheric pressure is applied to the inside of the upper lid F via the plug press P from the air pipe E continuously arranged on the upper lid F (fifth (see figure c). This air pressure can be set in a pressure range of about 1.1 to 10 atm, and in particular, pressurizing at about 2 to 3 atm for about 10 seconds is sufficient. During this pressurization, the air existing between the mold and the shaping surface of the mold is compressed, and the laminated material is further pressed down from the plug-pushing mold P, and is finally brought into pressure contact with the mold's shaping surface through the air gap. . This air gap acts as an air cushion with a uniform gap, and it becomes possible to form the laminated material to have a uniform thickness over the entire area even if it has a large uneven shape. After completion of this air pressure molding, the upper lid F moves upward to release the airtight state, and the molded product is removed from the mold M. When removing the mold, it is best to gradually open the upper lid F for about 110 seconds and allow the molded product to cool naturally. Rapid cooling is not preferable because it causes distortion in the molded product.

When the laminated material is shaped in this way, air pressure is applied to the laminated material from the base material b side to form the skin material a.
Since the side is pressed against the shaping surface of the mold M, there is no possibility of splitting or breaking the intermediate foamed resin layer c, and even if the foamed resin layer c is heated and softened, the laminated material is pressed with air pressure, so no bubbles are generated. It is possible to maintain good cushion performance without being crushed. In addition, since the air pressure is applied evenly over the entire surface of the molded product, it is possible to form a uniform thickness, and by pre-pressing to a certain extent with the plug press die P and applying air pressure, it is possible to ensure that the shaping surface of the mold M has a uniform thickness. Because of this, the laminated material can be shaped into a relatively large shape with uneven undulations.

Note that although a female mold was used as the mold in the above-mentioned embodiment, air pressure molding can be similarly performed using a male mold. In this case, the laminated material is placed with the base material b side facing the shaping surface of the mold, but since air pressure is applied from the skin material a side, the corners of the uneven undulations are sharp and beautiful without sagging. It can be formed into. In addition, in this pressure forming, air pressure is applied from the upper side of the laminated material to form the molded material, so an undercut portion U for drawing the laminated material in the horizontal direction of the mold M can also be formed at the same time. (See Figure 6 a, b). This undercut portion U can be formed as a pull pocket or a mounting seat surface for a door frame, but when forming a mounting seat surface for a door frame, a slide mold S is attached to the periphery of the mold M, and the undercut portion U is The molded product can be easily removed from the mold M by retreating the slide portion S of the cut portion U after molding.

Effects of the Invention As described above, according to the compressed air molding method of the present invention, the foamed resin layer of the intermediate layer is laminated while maintaining good cushioning performance without causing damage or crushing the foamed resin layer. Not only can the material be molded into a predetermined shape, but the laminated material can also be accurately shaped into a relatively large uneven shape by matching the shaping surface of the mold.

[Brief explanation of drawings]

1a, b and 2 a, b are explanatory diagrams showing problems when forming a laminated material having a foamed resin layer as an intermediate layer by a conventional mold forming method;
FIG. 3 is an explanatory diagram of a laminated material formed by the pneumatic mold forming method according to the present invention, FIG. 4 is an explanatory diagram showing the manufacturing process of the laminated material shown in FIG. 3, and FIGS. 5 a to c
are process explanatory diagrams of the compressed air mold forming method according to the present invention,
FIG. 6a is an explanatory diagram of the case where an undercut portion is molded by the pneumatic mold molding method according to the present invention, and FIG. 6b
FIG. 2 is a partial side sectional view showing an undercut portion. a: skin material, b: base material, c: foamed resin layer, M:
Mold, F: Upper lid, P: Plug press mold.

Claims (1)

[Claims] 1. When forming a sheet-like laminate material in at least three layers from a base material made of thermoplastic resin or the like and a skin material with a foamed resin layer interposed in the middle into a desired shape using a mold, the laminate material is formed into a desired shape using a mold. The material is heated and softened and placed on the shaping surface of the mold, and the molded part is pre-pressed with a plug press that approximately matches the shaping surface of the mold, and the molded part is kept airtight with a box-shaped top lid. A compressed air mold characterized in that air pressure higher than atmospheric pressure is applied to the inside of the mold through a plug-pressing mold after the mold is surrounded by the plug-pressing mold, and the laminated material is pressed against the shaping surface of the mold from the plug-pressing mold by the air pressure. Mold forming method.