JPH1158532A - Molding method for foamed resin products - Google Patents

Abstract

(57) [Problem] To provide a molding method of a foamed resin product capable of accurately molding a corner portion and shortening a molding time. A stretchable skin material set between a pair of upper and lower molds is heated and preformed, and a foamed resin material is injected into a space formed by the preformed skin material. A foamed resin product is formed by foaming the material. The foamed resin material is formed, for example, of beads obtained by prefoaming a pellet containing a foaming material, and the preforming is performed by suctioning the skin material with a vacuum pressure from a ventilation hole provided in one of the molds.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for molding a foamed resin product whose surface is covered with a skin material, and more particularly to a method for molding a foamed resin product capable of accurately molding a corner portion.

[0002]

2. Description of the Related Art Conventionally, foamed resin products whose surfaces are coated with various kinds of skin materials such as vinyl chloride sheets and nonwoven fabrics have been used for furniture and interior parts for automobiles, for example. As a method, for example, JP-A-8-24
No. 4059 discloses this.

[0003] In this molding method, as shown in FIG. 9, first, a stretchable skin material 53 whose center portion is curved downward in advance is set in an upper surface opening of a lower mold 51, and the curved portion of the skin material 53 is set. The foamed resin material 55 is injected into the storage chamber 54 formed between the upper mold 52 and the upper mold 52. Then, heating steam is circulated through the ventilation holes 56 of the lower mold 51 and the upper mold 52 into the cavity 57 to heat the foamed resin material 55 and the skin material 53, and after cooling and drying, release and finishing are performed. Thereby, a foamed resin product is molded.

[0004]

However, in this method of molding a foamed resin product, the skin material 53 is moved to the lower mold 51 by the pressure at the time of foaming of the foamed resin material 55 injected into the storage chamber 54. Since it is a method of deforming along the inner surface, there is a problem that it is difficult to accurately form the corner portion of the foamed resin product, and the molding time tends to be long.

That is, for example, when a foamed resin product 1 having a substantially rectangular parallelepiped shape as shown in FIG. 8 is formed, the pressure caused by the foaming of the foamed resin material 55 sufficiently acts on the corner 1a as shown in FIG. In many cases, a relatively large gap 58 is generated between the skin material 53 and the corner 51 a of the mold 51, and the corner 1 a of the foamed resin product 1 is
It becomes difficult to form a precise shape that conforms to the shape of the inner surface.

Further, a skin material 53 having a central portion curved downward.
At the time of injecting the foamed resin material 55 into the accommodation chamber 54 formed above and at the time of foaming of the injected foamed resin material 55, the reaction force of the skin material 53 is necessarily received, and the injection time and the foaming time are required. It becomes longer and the molding time tends to be longer.

The present invention has been made in view of such circumstances, and it is an object of the present invention to provide a method of molding a foamed resin product capable of accurately molding a corner portion and shortening a molding time.

[0008]

Means for Solving the Problems In order to achieve the above object, the invention according to claim 1 of the present invention preheats a stretchable skin material set between a pair of upper and lower molds by preforming, A foamed resin product is formed by injecting a foamed resin material into a space formed by the preformed skin material and foaming the foamed resin material.

With this configuration, the skin material covering the surface of the foamed resin product is first preformed by a pair of upper and lower molds, and the foamed resin material is placed in the space of the skin material formed by the preforming. Injected. Then, by foaming the foamed resin material, the space is filled with the foamed resin material at a predetermined magnification. At this time, the corner portion of the skin material, which has been preliminarily formed by the preforming, is pressed toward the inner surface of the corner portion of the mold under the pressure at the time of foaming of the foamed resin material, and the foamed resin material is injected into the space. The corner portion of the foamed resin product is accurately formed without receiving the reaction force of the skin material at the time.

According to a second aspect of the present invention, the foamed resin material is a bead obtained by prefoaming a pellet containing a foamed material.
The injection of the foamed resin material made of beads into the space is facilitated, the foaming time can be shortened, and the foaming of the foamed resin material is improved, so that the corner portion can be more accurately formed.

According to a third aspect of the present invention, a heated skin material set between a pair of molds is preformed by suctioning through a vent hole provided in one of the molds with a vacuum pressure. Features. With this configuration, the skin material can be vacuum-sucked from the air holes of the mold set at an appropriate position, and the corner portion can be more accurately formed.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. 1 to 7 show one embodiment of a method for molding a foamed resin product according to the present invention,
FIG. 1 is a process diagram, and FIGS. 2 to 7 are cross-sectional views for explaining the state of each process.

As shown in FIG. 2, a mold used in the molding method according to the present invention includes a container-shaped lower mold 2 having an open upper surface corresponding to the outer diameter of a foamed resin product; And a plate-shaped upper mold 3 for closing the upper surface. The lower mold 2 and the upper mold 3 are formed of, for example, a thin aluminum alloy material, and the lower mold 2 is provided with a vacuum suction hole 4 as necessary. An injection port 6 into which a bead 8 (see FIG. 5) as a foamed resin material is injected is formed in a cavity 7 formed by the lower mold 2 and the upper mold 3.

Using the lower mold 2 and the upper mold 3 to form a foamed resin product 1 as shown in FIG. 8, for example, is performed as follows. In the following description, reference numerals in parentheses correspond to reference numerals in the process chart of FIG. First, as shown in FIG. 2, the skin material 9 is set (K1) between the lower mold 2 and the upper mold 3. As the skin material 9, a sheet of a thermoplastic resin such as a vinyl chloride resin, a polycarbonate resin, or an acrylic resin, or a sheet of a material having a predetermined thickness and elasticity, such as a nonwoven fabric, is used.
Hot melt glue (not shown) is applied to b.

After the skin material 9 is set between the lower mold 2 and the upper mold 3, as shown in FIG. 3, the upper mold 3 is lowered to close the upper opening of the lower mold 2, and the vacuum of the lower mold 2 is reduced. Steam is supplied from the suction hole 4 and the air hole 5 of the upper mold 3 to the cavity 7 as shown by an arrow a.
And the whole of the front surface 9a and the back surface 9b of the skin material 9 is heated (K2). For this heating, for example, 110 ° C.
120 ° C. steam is used, and this steam is mainly supplied into the cavity 7 from the vacuum suction hole 4 of the lower mold 2 and discharged out of the lower mold 2 from another ventilation hole.
Then, the skin material 9 is heated.

When the skin material 9 is heated, the skin material 9 is preformed (K3). In this preforming, the air holes 5 of the upper mold 3 are closed, and as shown in FIG.
This is performed by sucking the inside of the cavity 7 as indicated by the arrow B with vacuum pressure. Due to this vacuum pressure, the skin material 9 located at the upper opening of the lower mold 2 is pulled downward (in the suction direction) and adheres to the inner surface of the lower mold 2. A space 10 substantially corresponding to the inner surface shape 2 is formed.

At this time, since the skin material 9 has elasticity and is heated, the skin material 9 is in a more flexible state, and is brought into close contact with the inner surface of the lower mold 2 by vacuum pressure. In the corner portion 2a, the corner portion 9c of the skin material 9 is substantially in close contact. The vacuum pressure is set to, for example, -760 mmHg, and the total time of the heating step (K2) and the preforming step (K3) of the skin material 9 is set to, for example, about 1 minute.

When the skin material 9 is preformed, the beads 8 are injected into the space 10 (K4). As shown in FIG. 5, the beads 8 are injected by removing a plug (not shown) closing the injection port 6 of the upper die 3 and opening the injection port 6, and opening the ventilation hole 5 of the upper die 3 as shown by arrow C. Suction.

As a result, a predetermined amount of beads 8 is injected from the inlet 6 into the space 10 as shown by the arrow D in the state of being sucked and supplied.
It is injected smoothly without receiving the reaction force of the skin material 9 inside. The beads 8 to be injected into the space 10 are preliminarily foamed to 8 to 9 times a pellet containing a foaming material having a foaming ratio set to, for example, about 10 times.

When a predetermined amount of the beads 8 is injected into the space 10, steam is supplied from the vacuum suction hole 4 of the lower mold 2 and the ventilation hole 5 of the upper mold 3 as indicated by an arrow E to heat molding (K).
5) Do it. The steam used for this heat forming is also from 110 ° C. to 120 ° C. as in the heating step K2 of the skin material 9.
The beads 8 injected into the space 10 are foamed to a predetermined magnification by the supply of the steam to form the foamed resin body 11 (see FIG. 6).

When the beads 8 are foamed in the space 10, the skin material 9 is pressed against the inner surface of the lower mold 2 at a predetermined pressure by the pressure at the time of the foaming, and is completely adhered to the corner 2 a of the lower mold 2. The corner portion 9c of the skin material 9 is also further pressed outward, and substantially adheres to the inner surface of the corner portion 2a of the lower die 2 as shown by a two-dot chain line in FIG. Further, by this heat molding, the hot melt glue applied to the back surface 9b of the skin material 9 and the outer peripheral surface of the foamed resin body 11 are bonded.

In this state, cooling (K6) by vacuum suction and spraying water, followed by demolding (K7),
As shown in FIG. 6, the molded product 12 is taken out from the lower mold 2 and the upper mold 3. Then, as shown in FIG. 7, trimming (K8) of cutting and finishing an excess portion 9d of the skin material 9 as shown by the arrow and finishing (K9), the surface of the skin material 9 as shown in FIG. 9, the foamed resin product 1 in a state where the foamed resin body 11 is filled therein is formed.

As described above, in the molding method of the above embodiment, before the beads 8 as the foamed resin material are injected into the cavity 7, only the skin material 9 is heated and the skin material 9 is vacuum-pressed. Since the preform is formed by suction, only the skin material 9 can be formed in advance along the inner surface shape of the lower mold 2, and the corner 9 c of the skin material 9 is attached to the corner 2 c of the lower mold 2.
Can be substantially adhered to each other.

Particularly, after the skin material 9 is preformed, the beads 8 are injected into the space 10 formed by the skin material 9 and foamed. 2 can be pressed further in the inner surface direction,
A large gap does not occur between the inner surface of the corner portion 2a of the lower die 2 and the corner portion 9c of the skin material 9 unlike the conventional case.
As a result, the corner portion 1a of the foamed resin product 1 can be formed into an accurate shape along the inner surface shape of the lower mold 2, and a high-quality foamed resin product 1 can be easily obtained. A great effect can be expected when applied to the foamed resin product 1 requiring quality.

In the above-mentioned molding method, the number of steps is increased as compared with the conventional molding method, but the entire molding time can be shortened. That is, the heating step (K2) and the preliminary forming step (K
3) The time of about 1 minute is sufficient, and the skin material 9 is formed in advance and the cavity is sufficiently ensured. Can be filled. Therefore, the foaming time in the mold can be shortened as compared with the conventional molding method. For example, the molding time which was required about 5 minutes in the past can be reduced to about 3 minutes. Can be shortened as compared with the molding method.

Further, since the unit price of the beads 8 is low, the material cost can be reduced, and a thin aluminum alloy material can be used for the lower mold 2 and the upper mold 3 to be used. For example, it is possible to mold the foamed resin product 1 at a low cost, for example, the mold cost can be reduced to / 10 or less. In addition, by appropriately setting the material and the like of the skin material 9, it is possible to easily form the foamed resin product 1 having various shapes, which is lightweight and whose surface is hardly damaged.

In the above embodiment, the foamed resin product 1 having a substantially rectangular parallelepiped shape has been described. However, the molding method according to the present invention is applied to furniture such as table boards and shelves, armrests for automobiles, and interior products such as sun visors. And so on. In addition, the conditions and the like of each step in the above embodiment are merely examples, for example, appropriate conditions can be set according to existing facilities, and the materials of the foamed resin material and the skin material also deviate from the gist of the present invention. To the extent not
Various changes can be made.

[0028]

As described in detail above, claims 1 to 3
According to the described invention, before injecting the foamed resin material into the pair of upper and lower molds, the skin material is heated and preformed, so that the skin material can be substantially adhered to the corner portion of the inner surface of the mold, The molding time can be shortened, for example, the corners of the foamed resin product can be accurately molded, and the preformation of the skin material eliminates the influence of the skin material during injection of the foam resin material and shortens the foaming time. Can be achieved.

[Brief description of the drawings]

FIG. 1 is a process diagram showing one embodiment of a method for molding a foamed resin product according to the present invention.

FIG. 2 is a sectional view showing a set state of the skin material.

FIG. 3 is a cross-sectional view showing a heating state of the skin material.

FIG. 4 is a sectional view showing a preformed state of the skin material.

FIG. 5 is a sectional view showing an injection state of the beads.

FIG. 6 is a sectional view showing the same mold release state.

FIG. 7 is a sectional view showing the trimming state;

FIG. 8 is a partially broken perspective view showing an example of a foamed resin product.

FIG. 9 is a cross-sectional view for explaining a conventional method for molding a foamed resin product.

FIG. 10 is a sectional view showing a state of a corner portion of the same.

[Explanation of symbols]

 1 foam resin product 1a corner 2 lower mold 2a corner 3 upper mold 4 5 Vent 6 Inlet 7 Cavity 8 Bead 9 Skin material 9a Front surface 9b Back surface 9c Corner portion 10 Space 11 Foamed resin body 12 Molded product

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI B29L 9:00 31:58

Claims (3)

[Claims] An extensible skin material set between a pair of upper and lower molds is heated and preformed, and a foamed resin material is injected into a space formed by the preformed skin material. A method for molding a foamed resin product, comprising molding a foamed resin product by foaming a resin material. 2. The method for molding a foamed resin product according to claim 1, wherein the foamed resin material is beads obtained by prefoaming a pellet containing a foamed material. 3. A preform is formed by sucking a heated skin material set between said pair of molds with a vacuum pressure from an air hole provided in one of said molds. 3. The method for molding a foamed resin product according to item 2.