JP4740035B2 - Skin molding method and powder slush molding device - Google Patents

Description

  The present invention relates to a skin molding method and a powder slush molding device used for automobile interior parts and the like.

Instrument panels, which are automotive interior parts, often have a skin integrated on the surface of the core material. Here, there are various methods for forming the skin, and among them, there is a powder slush method (for example, see Patent Document 1). In this construction method, a resin powder is put into a heated mold and the resin powder adhering to the mold is melted. And excess resin powder is collect | recovered and melted resin is made into predetermined thickness. Thereafter, the melted resin is cooled with water or air, and the resin solidified into a skin is taken out. The feature of this method is that if the powder resin adheres to the mold, it melts and becomes a skin, so the degree of freedom of shape is high, and the resin is sufficiently melted by the heat of the mold so that it is carved on the surface of the mold It is that a crest pattern or the like can be transferred at a high rate (the pattern transfer rate varies depending on molding conditions, but is about 90 to 95%).
Japanese Patent No. 2622075

  In the above powder slush method, the powder resin is put into the mold by rotating the preheated mold in the powder box containing the powder resin, and the powder resin adheres to the mold and melts. However, air remains in the gaps between the powders or between the powder and the mold, and pinholes (concave holes) are generated on the surface of the skin. The reason for this is that the resin powder includes small to large diameters, and when adhering to the mold, a large powder with a large weight falls first and adheres to the mold. This is because the gap between the powder and the mold becomes large. That is, when the large-sized powder adheres to the mold (FIG. 4B), the gap (shaded portion) is larger than when the small-sized powder adheres to the mold (FIG. 4A). Become.

  Therefore, a main object of the present invention is to provide a skin molding method and a powder slush molding device capable of molding a skin having a relatively small pinhole.

Means for Solving the Problems and Effects of the Invention

  The skin molding method of the present invention includes a preheating step for preheating the molding die, an assembling step for assembling the molding die so as to cover the opening of the powder box loaded with the resin powder, and a resin powder in the powder box. Or a first charge supply step for charging a negative charge, a second charge supply step for charging the mold with a charge having a polarity different from that of the resin powder, or grounding the mold, and rotating the assembly. The resin powder melted on the mold by rotating the assembly in which the powder box and the mold are assembled, and the curing step of attaching and melting the resin powder on the mold A recovery step of recovering a resin powder other than the above in a powder box, and a demolding step of removing the skin formed of the resin powder melted on the mold from the mold There.

  The powder slush molding device of the present invention includes a powder box loaded with resin powder, a mold that can be assembled to cover the opening of the powder box and preheated, and a resin powder in the powder box. Or a first charge supply means for charging a negative charge, and a second charge supply means for charging the mold with a charge having a polarity different from that of the resin powder or grounding the mold. A resin other than the resin powder melted on the mold after the resin powder is adhered onto the mold and melted by rotating an assembly in which the powder box and the mold are assembled It is characterized in that the powder is collected in a powder box.

  According to this configuration, since the resin powder in the powder box has a positive or negative charge, and the mold has a charge of a polarity different from that of the resin powder or is grounded, the particle size is small (weight) (Small) of resin powder is attracted to the mold. Accordingly, since most of the resin powder that melts on the mold is a resin powder having a small particle size, the gap between the powders or between the powder and the mold is relatively small, so that the skin having relatively small pinholes. Can be molded.

  In the skin molding method of the present invention, in the assembling step, the molding die and the powder box may be assembled in a state where an insulator is disposed between the powder box and the molding die.

  The powder slush molding device of the present invention may further include an insulator disposed between the powder box of the assembly and the mold.

  According to this configuration, it is possible to prevent short-circuiting when the powder box and the mold are assembled.

  The skin molding method of the present invention further includes a grounding step of stopping charging the resin powder in the powder box with a positive or negative charge and grounding the powder box before the recovery step. May be.

  According to this configuration, before the resin powder is collected in the powder box, the resin powder has no charge, and the powder box is grounded. It is possible to prevent the thickness of the formed skin from being increased by sucking, and to prevent the thickness of the skin from being varied in the charged state.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of a powder slush molding apparatus according to an embodiment of the present invention.

  The powder slush molding apparatus 1 in FIG. 1 grounds a powder box 10 loaded with a resin powder 11, a molding die 20, a voltage generator 5 that charges the powder box 10 with electric charges, and the molding die 20 (charges are charged). And a grounding device 6 for preventing charging. In addition, an insulator 30 made of a non-conductive elastomer such as silicon is disposed between the powder box 10 and the mold 20 to insulate them. FIG. 1 shows a state in which a molding die 20 used for molding a door trim-shaped skin that is an automobile interior part is assembled so as to cover the opening 10a of the powder box 10 after being preheated. Yes. Although not shown, the powder slush molding apparatus 1 has preheating means for preheating the mold 20 and rotating means for rotating the assembly in which the powder box 10 and the mold 20 are assembled.

  Examples of the resin powder 11 include a spherical shape obtained by suspension polymerization, and an angular shape obtained by freeze-pulverizing pellets. Moreover, the average particle diameter of the resin powder 11 is 100 to 500 μm, but includes particles having a small diameter of about 10 μm to particles having a large diameter of about 700 μm.

  In the present embodiment, when the voltage generator 5 applies a negative voltage to the powder box 10 such as stainless steel, the resin powder 11 in the powder box 10 is charged with a negative charge. On the other hand, the mold 20 is a powder slush mold formed by nickel electroforming, and is held at a ground potential (grounded).

  Next, the procedure of the skin molding method in the powder slush molding apparatus 1 will be described with reference to FIG. FIG. 2 is a diagram for explaining a method of forming the skin. In FIG. 2, the voltage generator 5 and the grounding device 6 are not shown.

  First, the mold 20 is preheated. Then, the preheated mold 20 is assembled so as to cover the opening 10a of the powder box 10 as shown in FIG. At this time, the insulator 30 is disposed between the mold 20 and the powder box 10. Thereafter, the resin powder 11 in the powder box 10 is charged with a negative charge, and the mold 20 is grounded. Then, as shown in FIG. 2B, the assembly in which the powder box 10 and the mold 20 are assembled is rotated. At this time, since the resin powders 11 all have the same charge (static electricity), the resin powder 11 having a small particle size is more easily attracted to the mold 20 than the resin powder 11 having a large particle size. Accordingly, the resin powder 11 having a small particle size mainly adheres to the mold 20 and melts (see FIG. 4A).

  When the resin powder 11 attached on the mold 20 is melted to form the skin 40 having a predetermined thickness, the powder powder 10 is charged by charging the powder powder 10 by grounding. Do not use. Thereafter, as shown in FIG. 2 (c), the assembly is rotated again to collect excess resin powder 11 other than the resin powder melted on the mold 20 in the powder box 10. Finally, after cooling the mold 20 with water, the skin 40 is removed from the mold 20.

  Next, as an embodiment of the present invention, a method for forming a door trim-shaped skin that is an automobile interior part will be described.

  In this example, suspension-polymerized thermoplastic polyurethane (average particle size: 170 μm) was used as the resin powder. In addition, a negative voltage of −45 kV was supplied to the powder box 10 by the voltage generator 5 and the mold 20 was grounded.

  First, after the mold 20 was preheated to about 250 ° C., the preheated mold 20 was assembled in the powder box 10 and rotated 1.5 reciprocations at a rotation speed of 3 seconds / time. At the same time as the rotation was completed, the voltage generator 5 was turned off and the powder box 10 was immediately grounded. Then, the powder box 10 and the shaping | molding die 20 were isolate | separated, the shaping | molding die 20 was cooled to about 60 degreeC with water, and the skin was demolded.

  When the appearance of the skin formed as described above was observed, the pinhole was clearly reduced as compared with the skin formed by the conventional method, and a good skin could be obtained.

  As described above, in the skin molding method of the present embodiment, the resin powder 11 in the powder box 10 has a negative charge, and the molding die 20 is grounded. The powder is sucked into the mold 20. Accordingly, since most of the resin powder that melts on the mold 20 is the resin powder 11 having a small particle size, the gap between the powders or between the powder and the mold is relatively small. The outer skin can be formed.

  Further, by grounding the powder box 10 before the excess resin powder 11 is collected in the powder box 10, the resin powder 11 is sucked into the mold 20 when the excess resin powder 11 is collected. Accordingly, it is possible to prevent the thickness of the skin 40 to be formed from becoming thick and to prevent the thickness of the skin 40 from being varied in a charged state.

  Moreover, since the insulator 30 for insulating these is arrange | positioned between the powder box 10 and the shaping | molding die 20, when the powder box 10 and the shaping | molding die 20 are assembled, it prevents that it short-circuits. be able to.

  The preferred embodiment of the present invention has been described above. However, the present invention is not limited to the above-described embodiment, and various design changes can be made as long as they are described in the claims. . For example, in the above-described embodiment, resin powder having a negative charge is put into a grounded mold, but resin powder having a positive charge may be put into a grounded mold. . Further, as shown in FIG. 3, the powder slush molding device includes a voltage generator 5 that charges the powder box 10 and charges, and a voltage generator 6 a that charges the molding die 20. The resin powder having a negative charge may be put into the molding die 20 having a charge having a polarity different from that of the resin powder. In this case, the resin powder and the mold are charged with charges of different polarities, so that the resin powder can be more efficiently attached to the mold than in the above-described embodiment.

It is a figure which shows schematic structure of the powder slush molding apparatus which concerns on embodiment of this invention. It is a figure explaining the shaping | molding method of a skin. It is a figure which shows schematic structure of the other powder slush molding apparatus which concerns on embodiment of this invention. It is a figure which shows the clearance gap formed between powders or between a powder and a shaping | molding die.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Powder slush molding device 5 Voltage generator 6 Grounding device 6a Voltage generator 10 Powder box 11 Resin powder 20 Mold 30 Insulator 40 Skin

Claims (5)

A preheating process for preheating the mold;
An assembly process for assembling the mold so as to cover the opening of the powder box filled with the resin powder;
A first charge supplying step of charging a positive or negative charge to the resin powder in the powder box;
A second charge supplying step of charging the mold with a charge having a polarity different from that of the resin powder or grounding the mold;
A curing step of causing the resin powder to adhere to the mold and melt by rotating an assembly in which the powder box and the mold are assembled;
A recovery step of recovering in the powder box resin powder other than the resin powder melted on the mold by rotating the assembly;
And a demolding step of removing the skin formed of the resin powder melted on the mold from the mold.   2. The skin molding according to claim 1, wherein in the assembly step, the molding die and the powder box are assembled in a state where an insulator is disposed between the powder box and the molding die. Method.   2. The method according to claim 1, further comprising a grounding step of stopping charging the resin powder in the powder box with positive or negative charges and grounding the powder box before the collecting step. Alternatively, the method for forming a skin according to 2. A powder box loaded with resin powder;
A mold that can be assembled and preheated to cover the opening of the powder box;
First charge supply means for charging a positive or negative charge to the resin powder in the powder box;
The mold is provided with second charge supply means for charging a charge having a polarity different from that of the resin powder or grounding the mold.
By rotating the assembly in which the powder box and the mold are assembled, the resin powder is adhered onto the mold and melted, and then the resin powder other than the resin powder melted on the mold A powder slush molding device characterized in that resin powder is collected in a powder box.   The powder slush molding apparatus according to claim 4, further comprising an insulator disposed between the powder box and the mold of the assembly.

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