JPS63293011A - Monolithic foam molding method - Google Patents

Abstract

PURPOSE:To prevent short molding of a foamed body or swell of a skin material from generating, by a method wherein the skin material and a core material of a permeable material are fitted respectively to one side molding surface and the other side molding surface of a molding tool by forming a space on the backside, foamable raw material supplied between the skin material and core material is foamed and the foregoing space is depressurized. CONSTITUTION:After a skin material 6 and permeable core material 7 have been fitted respectively to a molding surface of a bottom force 2 and that of a top force 3, a urethane foaming stock solution 11 is supplied over the skin material 6. The urethane foamable stock solution 11 is foamed by clamping the top and bottom force 3, 2. Gas to be generated within a cavity at the time of foaming is sucked through the core material 7 by depressurizing a depressurizing cavity 8 directly before completion of the foaming. With this construction, it is possible to prevent defective molding such as an air rich area or a void from generating and to reduce also swell to be generated at the time of demolding.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention involves setting a skin material and a core material in a foam mold,
The present invention relates to an improvement in an integral foam molding method in which a foaming raw material such as urethane is foamed between the skin material and the core material to integrally mold the skin material and the core material.

(Prior Art) In recent years, many integral foam molded products in which a skin material, a foam material, and a core material are sequentially laminated have been used for interior parts such as automobile instrument panels.

The general molding method for this integral foam molded product is to set the skin material, which has been formed in advance by vacuum forming or slush molding, into the lower mold of the foam mold, and then to form the core material, which is formed by press molding or injection molding. is set in the upper mold, a foaming raw material such as urethane is supplied between the skin material and the core material, the upper mold and the lower mold are closed, and the foaming material is foamed inside to form the skin material,
The foam and core material are laminated to form an integrated product. (Reference: Tomo of Technology (Published by Toyota Motor Corporation Toyota Engineering Society), Vol.

30, No2. 1978, P180-P181)
By the way, during foam molding, a large amount of gas is generated from the foaming raw material. Therefore, when the foaming raw material foams and fills the mold (cavity), there is no place for the gas to escape, resulting in air pockets, or the foam or gas is drawn in, creating voids or roughening the foam cells. There was a problem.

There are also problems such as short-circuits where the foam does not fully fill the mold due to air pockets and voids, or defects such as blisters that occur in the less rigid skin material due to high internal pressure after demolding the molded product. there were.

Conventionally, in order to solve these problems, there have been methods in which the injection locus of the foaming raw material is changed or a slab is pasted inside the cavity to control the flow of the foaming raw material during foaming and prevent air pockets.

In addition, in order to solve the above problem, the present applicant has filed a patent application
There is a technique described in No. 1-274741).

This technology is characterized by interposing an air permeable porous member between the foam and the core material, and the internal gas generated from the foam raw material during molding is absorbed through this air permeable porous member. is discharged to the outside.

(Problem to be solved by the invention) However, the injection trajectory of the conventional foaming raw material is changed,
When applying slabs to control flow, the optimal position must be set according to the shape of the molded product, which requires a great deal of study and work, and must be done for each individual molded product. However, there were problems in that productivity was extremely low and costs were high.

Furthermore, in the method described in Japanese Patent Application No. 61-274740, it is necessary to attach a breathable porous member to each molded product, which has problems such as poor workability and high product cost. There was a point.

The present invention has been made in view of one or more problems, and it is an object of the present invention to
The purpose is to prevent defects such as short circuits and blisters.

As a means to solve the above problems and achieve the objective, a skin material is attached to the molding surface of either the upper mold or the lower mold of the foam mold, and the A core material made of a breathable material is attached to the molding surface of the mold with a space formed on the back side, and a foaming material is supplied between the skin material and the core material, and then the upper mold and the lower mold are The mold is closed and the foaming raw material is foamed within the cavity, and the space on the back side of the core material is depressurized and the inside of the cavity is evacuated for molding.

(Function) In this way, by reducing the pressure in the space on the back side of the breathable core material, the gas generated when foaming raw material is foamed is efficiently discharged to the back side through the core material. Air pockets and voids are no longer generated, and defects such as short circuits and blisters can be prevented.

Furthermore, since no separate member is attached, there is no reduction in productivity or increase in cost.

(Example) Next, an example of the present invention will be described based on the drawings. In this example, integral foam molding of an automobile instrument panel will be explained.

First, FIG. 1 shows a foaming mold l according to the present invention, which includes a lower mold 2 and an upper mold 3 that is rotatably supported on the side surface of the lower mold 2 and forms a cavity together with the lower mold 2. and upper mold 3
It is generally composed of expandable, thick rotating cores 4 and 5 provided on the upper surface of the holder.

A skin material 6 made of vinyl chloride or the like is attached to the molding surface of the lower mold 2.

In addition, a breathable core material 7 is attached to the upper mold 3,
A vacuum cavity (space) 8 is formed on the back side of the core material 7 . Note that the core material 7 may be any material as long as it has a permeability level of 1 and does not leak the foaming raw material, and examples thereof include paper, ceramics, and wood materials.

In addition, it is not necessary to make the entire core material 7 a breathable material; instead, as shown in FIGS. , other parts (
Part B) may be molded from resin. Here, FIG. 5 is a diagram showing the relationship between the air pressure and ventilation amount of the core material 7 used in this example, and shows that the air permeability is 4 to 69/min at an air pressure of I Kg/cm. It has the following.

A vent hole 3a is formed in the upper die 3 to communicate the vacuum cavity 8 with the outside, and the outlet side of the vent hole 3a is connected to a suction pipe 9. In addition, the suction pipe 9 is
It is connected to the vacuum pump 10, and the pressure inside the vacuum cavity 8 is reduced through the suction pipe 9 by the operation of the vacuum pump IO.

The operation related to the above configuration will be explained.

As shown in FIG. 2, after opening the upper mold 3 and attaching the skin material 6 to the molding surface of the lower mold 2 and attaching the breathable core material 7 to the molding surface of the upper mold 3, A certain urethane foaming stock solution 1
1 is supplied onto the skin material 6 from the injection machine 12.

Subsequently, as shown in FIG. 1, the upper mold 3 and lower mold 2 are closed, and the urethane foaming stock solution 11 is foamed inside. Immediately before foaming of the urethane foaming stock solution 11 is completed, the vacuum pump 10 is operated to reduce the pressure in the vacuum cavity 8 on the back side of the core material 7.
The gas generated in the cavity during foaming or the core material 7
It will be sucked through. Then, the sucked gas passes through the suction pipe 9 and is discharged from the vacuum pump 10 to the outside.

After the molding is completed, the upper mold 3 and rotating core are opened and the molded product 13 is taken out from the lower mold 2, as shown in FIG.

As described above, the gas in the cavity can be exhausted during foam molding, preventing the formation of air pockets and short circuits.Furthermore, it is possible to reduce the internal pressure, so the skin material 6 generated during demolding can be prevented. This means that blistering can be prevented, and molding defects of the instrument panel can be significantly reduced.

Note that the present invention is not limited to the above embodiments,
Any transformation or change is free as long as it does not deviate from the purpose, structure, or effect.

(Effects of the Invention) As explained in detail above, the present invention exhausts the inside of the cavity through the core material during integral foam molding, so that
It is possible to prevent molding defects such as air pockets, voids, and short circuits without reducing productivity, and it also reduces internal pressure and reduces blisters that occur during demolding of molded products.

Furthermore, in order to reliably discharge the gas generated during foam molding, a larger amount of foaming agent is used and the density of the foam is lowered, thereby reducing the cost of raw materials and the weight of the molded product.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view of the integral foaming mold according to the embodiment of the present invention in a state in which the foaming raw material is being foamed, and FIG. 2 is a longitudinal cross-sectional view of the integral foaming mold shown in FIG. 1 during injection of the foaming raw material. FIG. 3 is a longitudinal cross-sectional view showing the state in which the molded product is taken out after completion of molding in the integral foaming mold shown in FIG. 1; FIGS. 4(a) and 4(b) are perspective views showing the core material, respectively; FIG. 5 is a diagram showing the relationship between air pressure and ventilation amount, which indicates the air permeability of the core material. 1... Foaming mold 2... Lower mold 3... Upper mold 6... Skin material 7... Core material 8... Decompression cavity (space) 11... Urethane foam stock solution (foaming raw material) ) Patent applicant
Toyota Motor Corporation Figure 1 Figure 4 Figure 5

Claims (1)

[Claims] (1) Attach a skin material to the molding surface of either the upper or lower mold of the foam mold, place a core material made of a breathable material on the molding surface of the other mold, and leave a space on the back side. After forming and attaching the material, and supplying the foaming raw material between the skin material and the core material, the upper mold and the lower mold are closed to foam the foaming material in the cavity, and the foaming material is foamed on the back side of the core material. An integral foam molding method characterized in that molding is performed by reducing the pressure in the space and evacuating the inside of the cavity.