JP2984566B2 - Method for manufacturing hollow resin molded product and gas injection hole sealing device therefor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a hollow resin molded product by gas injection molding, and to an apparatus for sealing a gas injection hole of the molded product.

[0002]

2. Description of the Related Art In a gas injection molding method, a hollow portion can be formed while gas injected into an uncured resin in a cavity passes through a thick portion and presses the resin against a mold surface. A molded article having an excellent appearance without sink marks can be produced. Since gas injection molding has such advantages, it is widely used in various fields.

However, the resin molded product obtained by this method has a gas injection hole having a diameter of about 3 to 5 mm. This hole is usually provided at a position where the user does not see it, or is covered with a soft resin in order to further improve the appearance and tactile sensation by using this molded product as a core material (insert body). ing. However, in the former case, intrusion of water or dust cannot be prevented, and in the case of resin coating, the coating resin intrudes from the gas injection holes, which not only wastes the resin but also reduces the weight. Is also killed.

[0004] In order to solve such a drawback of the resin molded product by the gas injection molding method, the injection hole is sealed by welding the gas injection hole of the molded product with a sealing member made of the same material as the molded product. It has been proposed (JP-A-4-220318). It has also been proposed to seal the gas injection port by melting the projection of the gas injection port with a soldering iron and forming the same on the same plane as the back surface of the molded product (Japanese Patent Laid-Open No. 6-190857).

[0005]

In the former method, the gas injection hole of the molded article can be closed, and therefore, when the resin is further coated with the resin, the resin wastefully enters the hollow portion as described above, thereby impairing the lightening effect. There is no. However, for that purpose, a step of separately molding the sealing member, a step of filling it into the injection hole, and a welding step are required, and complicated management of the sealing member itself according to the type of molded product as a part is also required. In other words, there is a problem in productivity.In addition, the sealing member is formed by welding and fixed, and there is a possibility that the sealing member may fall off, and a slight gap may be generated between the sealing member and the main body. When used as an insert, the coating material penetrates into the inside of the hollow, resulting in a short shot product and poor appearance.

In the latter case, the soldering iron is fixed only at the surface portion, and the melted material that has entered only enters the hollow portion of the molded product, so that the strength of this portion is insufficient. Therefore, when the hollow article is further molded in two colors as an insert body, the fusion portion of the gas injection port may be broken by the injection resin pressure, and the coating resin may enter the product.

[0007] Under such circumstances, the present invention provides a means for closing a gas injection hole of a hollow molded article which does not require an extra part and therefore does not require the production and management of the part and which is easy to operate. Accordingly, it is an object of the present invention to provide a method of manufacturing a hollow resin molded product that prevents a resin from entering a hollow portion of a hollow insert body and that can effectively use a coating resin without waste. A further object of the present invention is to provide a gas injection hole sealing device for the production method.

[0008]

According to the present invention, as a result of diligent studies, a resin overhang is provided around the periphery of a gas injection hole of a hollow resin molded article to seal the injection hole, and this overhang is heated. However, the present inventors have found that the above problem can be solved by sealing the gas injection hole, and have reached the present invention.

That is, the present invention provides: (1) a hollow resin molded article having a projection portion for sealing the injection hole formed around the gas injection hole by a gas injection molding method, and then forming the projection portion. This is a method for manufacturing a hollow resin molded product in which the gas injection hole is sealed by caulking under heating.
The gas injection hole has a tapered structure toward the inside of the molded product.
Hollow resin molded article manufacturing method, characterized in that there, (2) the tapered structure is tapered (1) The method of producing a hollow resin molded article according, (3) the tapered structure is stepped ( 1) The method for producing a hollow resin molded article according to the above. ( 4 ) By a gas injection injection molding method, a hollow resin molded article having an overhang portion for sealing the injection hole is formed around the periphery of the gas injection hole, and then the overhang portion is caulked under heating to form the gas injection hole. the sealing-obtained hollow resin molded article inserted into the mold cavity, the resin-coated method for producing hollow resin molded article characterized by injecting the coating resin, (5) gas injection injection molding A sealing device for caulking the overhang portion of a hollow resin molded product having a protrusion formed on the periphery of the gas injection hole formed by a method under heating, which can be positioned outside the overhang portion of the periphery of the gas injection hole. After the caulking guide and the caulking guide are slidably inserted into the caulking guide and positioned outside the overhang, the caulking guide is slid inside the caulking guide and the overhang is heated. Caulking Hollow resin molded article of the gas injection hole sealing device characterized by comprising a crimping tool, relates.

In the method for producing a hollow resin molded product of the present invention,
As described above, first, a hollow resin molded product serving as an insert body is molded by the gas injection molding method. At this time, an overhanging portion for sealing the gas injection hole is formed at the periphery of the gas injection hole. FIG. 1 is a partial schematic view before an assist grip, which is an example of a product manufactured according to the present invention, is covered with a skin layer, and FIG. 2 is a cross-sectional explanatory view of FIG. The overhanging portion is also provided for preventing gas leakage, which is provided upright around a gas injection pin (indicated by reference numeral 3 in FIG. 2) protruding into a mold cavity (this pin mark remains as a gas injection hole 2 in a molded product). It may be an annular piece that also functions. FIG. 3 is an explanatory view of a mold for molding the molded article shown in FIG. 2. 4a, 5a, 6a and 7a.
Alternatively, those shown by the annular pieces 3 in FIGS. 8A and 8C may be used. Further, the overhanging portion is caulked under heating to seal the gas injection hole. Therefore, the structure of the overhanging portion is not limited to the above-described annular structure, and any shape and structure that can seal the gas injection hole by caulking under heating may be used. Department.

The overhanging portion can be caulked by an appropriate caulking tool such as a soldering iron, an ultrasonic welding machine or a vibration welding machine. Can be.

In the method of manufacturing a hollow resin molded product according to the present invention, in the molding of the insert body as described above, a projecting portion is provided on the periphery of the gas injection hole, and this is caulked under heating to form the gas injection hole. Sealing is important, and other matters are not particularly limited.

That is, after the gas injection hole is sealed by caulking of the overhang portion, this hollow resin molded product is set as an insert in a mold cavity, and the coating resin is injected into the cavity to form a skin layer. Although it is formed, the resin used for the hollow resin molded product (insert body) and the resin for coating are not particularly limited, and the molding conditions at that time are not particularly limited. However, as the resin for molding the insert body, for example, polyolefin such as polyethylene and polypropylene, polystyrene, ABS, polycarbonate, polyacetal, polyester, nylon and the like are preferable.

As the coating resin, polyurethane, polyvinyl chloride, thermoplastic elastomer and the like are preferable.

[0015] The method of the present invention is particularly useful for the production of molded articles generally coated with an insert having a hollow portion.

[0016]

9 to 12 are schematic explanatory views of a gas injection hole sealing apparatus according to the present invention. This apparatus is used to caulk an overhanging portion provided at the periphery of a gas injection hole of a hollow resin molded product under heating. For explaining the pattern for sealing the gas injection hole.

In FIG. 9, reference numeral 1 denotes a hollow resin molded product formed by gas injection molding, and the molded product 1 has a gas injection hole 2 as a trace of a gas injection pin. At the periphery of the injection hole 2, an annular piece 3 as an overhanging portion for preventing injection gas leakage is provided.

Reference numeral 4 denotes a caulking jig for caulking the projecting portion 3 at the periphery of the gas injection hole under heating to seal the gas injection hole. The caulking jig includes a heating device 5, a caulking device 7 heated by the heating device, and a slidable insertion of the caulking device 7,
The swaging tool guide 6 guides the swaging tool 7 to the overhang portion. Positioning is performed by swaging guide 6
Is preferably brought into contact with the outside of the overhang. The inside of the tip of the caulking tool guide 6 is formed in a frusto-conical taper to guide the protruding portion inward. In FIG. 9, reference numeral 13 denotes a holding member for the caulking guide 6, which is an outer cylinder for placing and holding the caulking guide on the lower end flange portion 15. Reference numeral 14 denotes a heat radiation hole. Reference numeral 16 denotes a mounting portion of the caulking tool 7, and the caulking tool 7 is screwed into a threaded portion at the center of the suspended column. The caulking jig 4 is driven along the guide rod 9 by an actuator 8 such as a hydraulic cylinder connected to a holding body 10 holding the caulking jig. A stopper 11 is attached to the guide rod.

9 to 12 show the holding member 1 of the caulking jig.
0 and the molded product 1 show a cross section.

FIG. 10 shows a state in which the caulking jig 4 is lowered by the actuator 8, and the caulking tool guide 6 is aligned with the annular piece 3 as the projecting portion of the hollow resin molded product 1 and is in contact therewith. Here, the swaging tool guide 6 is in a stopped state.

When the caulking jig is further lowered until it comes into contact with the stopper 11, the caulking jig 7 as shown in FIG.
Only the caulking slides down the guide and heats the annular piece 3,
The crimped shape 12 is formed by crushing, and the gas injection hole is sealed. When the swaging is completed, as shown in FIG.
Is raised by the actuator 8, and the sealing operation of the gas injection hole of the hollow resin molded product is completed.

In this way, the hollow resin molded product in which the gas injection hole is sealed is then inserted into the mold cavity and the coating resin is injected to form a skin layer.
Since the caulked portion is covered with the skin layer, the appearance is not affected.

Further, in addition to the shape shown in the above embodiment, the overhanging portion at the periphery of the gas injection hole has a groove 3b at the base of the outer periphery of the overhanging portion 3 as shown in FIG.
5a, arranged slightly outside of the gas injection hole 2 as shown in FIG. 5a, as shown in FIG.
As shown in FIG. 7a, the overhanging portion (annular piece) is formed inside the gas injection hole 2, and further, as shown in FIGS. 8a and 8c, the tip of the gas injection pin in the mold is tapered and tapered. If the taper is tapered stepwise or stepwise, the inner surface (3a) of the annular piece as the overhanging portion also becomes tapered or stepped, and the diameter of the injection hole (2) becomes small, so that the caulked resin does not fall. The sealing is performed more reliably. As shown in FIG.
In the case of a and c, since the strength of the caulked portion is further increased, the caulked portion is broken by the resistance of the tapered portion even when an injection resin pressure is applied when the hollow molded article is coated with the resin as an insert body. The fear of doing so can be completely eliminated. Any of the above types can form a swaged shape 12 as shown in each figure b.

[0024]

As described above, according to the present invention,
Since the gas injection hole of the hollow resin molded product manufactured by the gas injection injection molding method can be sealed by caulking,
Unlike the conventional case, there is no need to manufacture and manage a separate component for sealing, so that productivity can be increased. Further, according to the gas injection hole sealing device of the present invention, since the caulking tool guide is provided outside the overhanging portion of the peripheral edge of the gas injection hole, the positioning and the caulking operation of the caulking tool can be performed accurately.

Moreover, in the sealing of the present invention by caulking the protruding portion at the periphery of the gas injection hole, there is no generation of a gap where the welded part is likely to fall off. In the case where the resin does not invade and the product is used as it is without performing secondary molding, it is possible to completely prevent intrusion of water, dust and the like.

[Brief description of the drawings]

FIG. 1 is a partial schematic view of an assist grip for a vehicle, which is an example of a hollow resin molded product manufactured according to the present invention, before being covered with a skin layer;

FIG. 2 is an explanatory sectional view of FIG. 1;

FIG. 3 is a schematic explanatory view of a main part of a mold for molding the molded article shown in FIG. 2;

FIG. 4 is an explanatory view showing an example (a) of an annular piece as a protruding portion at the periphery of a gas injection hole and a shape (b) obtained by caulking it.

FIG. 5 is an explanatory view showing another example (a) and a swaged shape (b);

FIG. 6 is an explanatory view showing another example (a) and a swaged shape (b) thereof;

FIG. 7 is an explanatory view showing another example (a) and a swaged shape (b) thereof;

FIG. 8 is an explanatory view showing a crimped shape (b) of still another example (a), (c) and (a);

FIG. 9 is a schematic explanatory view of a gas injection hole sealing device of the present invention,

FIG. 10 is an explanatory view showing a state in which the caulking jig 4 is lowered and the caulking tool guide 6 is in contact with the annular piece 3 in the gas injection hole sealing device of the present invention;

FIG. 11 is an explanatory view showing a state in which the annular piece 3 is heated, crushed and caulked by the caulking tool 7 lowered in the gas injection hole sealing device of the present invention;

FIG. 12 is an explanatory view of the gas injection hole sealing device of the present invention in a state where the caulking jig 4 has risen after the caulking is completed.

[Explanation of symbols]

 2 Gas injection hole 3 Overhang 4 Caulking jig 6 Caulking guide 7 Caulking

Claims (5)

(57) [Claims] 1. A hollow resin molded article having an overhanging portion for sealing the injection hole is formed at the periphery of the gas injection hole by a gas injection injection molding method, and then the overhanging portion is caulked under heating to perform gas injection. Method for producing hollow resin molded article for sealing holes
Wherein the gas injection hole tapers toward the inside of the molded article.
A method for producing a hollow resin molded product having a structure . 2. The method according to claim 1, wherein the tapered structure has a tapered shape. 3. The method according to claim 1, wherein the tapered structure has a stepped shape. 4. A hollow resin molded article having an overhanging portion for sealing the injection hole is formed at the periphery of the gas injection hole by a gas injection injection molding method, and then the overhanging portion is caulked under heating to perform gas injection. inserted a hollow resin molded article obtained by sealing the hole in the mold cavity, the resin-coated production method of the hollow resin molded article characterized by injecting the coating resin. 5. A sealing device for caulking under heat the hollow portion of a hollow resin molded product in which a gas injection hole formed by a gas injection injection molding method and having a projecting portion arranged around the periphery of the gas injection hole,
After the caulking guide is slidably inserted into the caulking guide and the caulking guide disposed so as to be positioned outside the overhang of the gas injection hole, the caulking guide is positioned after the caulking guide is positioned outside the overhang. A device for sealing a gas injection hole of a hollow resin molded product, comprising: a caulking device that slides inside the caulking device to caulk an overhang under heating.