JPH11126528A - Grommet and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reliably manufacture a grommet with no gap in an integrated part with a wire harness by a manufacturing method for the grommet molded integrally with a wire harness by injection molding. SOLUTION: A wire harness (W/H) set with a part to be integrated with a grommet in a mold 50 for molding a grommet is heated by electricity application and a molding material is injected to fill the mold 50. After that, current conduction to the wire harness (W/H) is stopped to cool and solidify the resultant molding material and to produce this grommet 100.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a grommet, which fits into a through-hole through which a wire harness provided in a vehicle body panel or a glass panel of an automobile is inserted to prevent water from flowing through the through-hole. When the grommet is integrally formed with the wire harness by injection molding, the grommet can more reliably stop water between the wires of the wire harness held in the grommet.

[0002]

2. Description of the Related Art Normally, a through-hole for inserting and arranging a wire harness (W / H) is provided in a vehicle body panel that separates an interior of an automobile from an engine room and the like. Grommets are attached to prevent water from entering the room.

The grommet is generally provided with a reduced diameter portion for holding an electric wire and a fitting groove which is continuous with the reduced diameter portion and provided on its outer peripheral surface with a fitting groove for fitting into a peripheral wall portion of a through hole of a vehicle body panel. Department.

[0004] In recent years, it has been considered that water enters a room from an engine room or the like through a gap between wires of a wire harness (W / H) held in a grommet. Countermeasures for stopping water are required.

Therefore, as shown in FIG. 3, there has been proposed a grommet 10 manufactured by injection molding integrally with a portion of a wire harness (W / H) to be held in a grommet. However, in the grommet 10, when the wire harness (W / H) to be integrated is formed by bundling and binding three or more electric wires vertically and horizontally and binding the outer shape to a substantially circular or polygonal shape, the three The gap 11 (FIG. 4) formed between the electric wires w is not filled with the grommet material,
There is a problem that water infiltrates from the gap 11 and water cannot be reliably stopped. Therefore, in order to eliminate such inconvenience, a disk-shaped spacer 20 having a plurality of electric wire holding grooves 21 formed on the outer peripheral surface shown in FIG. 5 is inserted into the inside of the wire harness (W / H), and the electric wire holding groove is formed. The wire 21 of the wire harness (W / H) is held in the space 21 so that a space where the molding material can be filled is provided between the wires. In this state, the insertion portion of the spacer 20 of the wire harness (W / H) is inserted into a mold. And the grommet is molded. FIG. 6 shows the grommet 30 thus manufactured.

[0006]

On the other hand, when the number of wire harnesses (W / H) integrated with the grommet is two or less, or when the number of electric wires w is three or more as shown in FIGS. Even if the grommet material (rubber, elastomer) is excellent in fluidity in the mold, the grommet material is filled in the concave portion 12 between the electric wires, even if the grommet material (rubber, elastomer) is excellent in fluidity. No gap is formed around the integrated electric wire. However, if the grommet material is P
When the fluidity in the mold such as VC (polyvinyl chloride) elastomer is poor, the recess 12 between the electric wires may not be filled with the grommet material, and there is a problem that the water cannot be reliably stopped. .

Further, even if the above-described method of providing a large space between electric wires by using the spacer is used, the grommet material has poor fluidity in a mold such as a PVC (polyvinyl chloride) elastomer, so that the electric wire coating and If the adhesiveness is not good, the periphery of the electric wire separated by the spacer may not be able to be reliably covered with the grommet material, and the waterproofness may be reduced.

The present invention has been made in view of the above circumstances, and in a method of manufacturing a grommet integrally formed with a wire harness by injection molding, a grommet having no gap in an integrated portion with the wire harness is reliably manufactured. The task is to be able to do so.

[0009]

According to the present invention, there is provided a grommet manufacturing method for manufacturing a grommet integrally formed with a wire harness by injection molding. The temperature of the wire harness in which the part to be integrated with the grommet is set in the mold is raised by energization, and the mold is injected and filled with the molding material. Then, the energization of the wire harness is released to cool and solidify the molding material. A grommet manufacturing method is provided.

According to this manufacturing method, when the molten molding material injected into the mold reaches the periphery of the wire harness, each wire of the wire harness is heated by energization. Is not rapidly cooled by the electric wires, and penetrates well into the recesses and gaps between the electric wires while maintaining its molten state. Therefore, thereafter, when the energization is released and the molding material is cooled and solidified, a grommet without a gap can be reliably formed at a portion integrated with the wire harness.

The energization of each wire of the wire harness is performed by connecting both terminals of the wire harness to an external power supply to form a current circuit. For example, this can be easily performed by attaching a connector to the end of the connection wire connected to the power supply and connecting the connector attached to the end of the wire harness.

It is preferable that the temperature of the electric wire is increased to a predetermined temperature in the shortest possible time, and then the mold is immediately filled with a PVC elastomer by injection, and the energization is released immediately after the filling. This is because if the time for which the temperature of the electric wire is increased is long, the properties of the outer sheath of the electric wire may be greatly changed. When an overcurrent is applied to the electric wire, the temperature of the electric wire can be raised in a short time.

The heating temperature of the electric wire is set at a temperature not higher than the melting point of the resin sheath (usually a vinyl chloride resin) of the electric wire, and as high as possible within a range in which the properties of the sheath do not suddenly change.
For example, when the molding material is a PVC elastomer, the injection temperature is 180 ° C., and the temperature of the electric wire is preferably raised to about 140 ° C. This is because the outer sheath of the wire made of vinyl chloride resin starts plasticizing at 120 ° C or higher and 140 ° C.
This is because, when the ratio exceeds 1, the plasticization progresses rapidly and the property change becomes large.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of the grommet manufacturing method of the present invention. In FIG. 1A, 5
Reference numeral 0 denotes a grommet molding die, and a portion 61 to be integrated with the grommet of the wire harness (W / H) is set in a die portion 51 in the die 50. The wire harness (W / H) here is obtained by bundling a plurality of electric wires w shown in FIG. 7 and binding them with an adhesive tape T. It consists of four electric wires w, one end of which is connected to one male connector 62 common to the four electric wires, and the other end is divided into two pieces each and bound with adhesive tape t to form two bundles. Branching is performed, and male connectors 63A and 63B are attached to each wire bundle.

A connector 62 at one end of the wire harness (W / H) is connected to one connecting wire 71 from a power source 70.
And the other end connectors 63A and 63B are respectively connected to the female connectors 74A and 74B attached to the ends of the other branched connection wires 73A and 73B from the power supply 70. ing.

In this state, first, power is supplied to the wire harness (W / H) by the power supply 70, and the wire harness (W / H) is supplied.
H) Each electric wire w is heated to a predetermined temperature. For example, when molding a grommet with a PVC elastomer, 140 ° C.
Raise the temperature to

Immediately after the electric wire w reaches a predetermined temperature, the molten material of the grommet molding material is discharged from an injection nozzle (not shown) brought into contact with the injection port 52 of the molding material of the grommet molding die 50. The molten material 53 is injected into the mold part 51 as shown in FIGS. 1B and 1C. At this time, even if the molten material 53 of the grommet molding material injected into the mold part 51 reaches the periphery of each electric wire w of the wire harness, the electric wire has been heated to near the melting point of the grommet molding material. Without being cooled by the electric wire, it penetrates well into the recesses and gaps between the electric wires w while maintaining its molten state.

Immediately after the filling is completed, the power supply to the wire harness (W / H) by the power supply is released, and the wire harness (W / H) is released.
H) Disconnect the connectors 62, 63A, 63B from the connectors 72, 74A, 74B of the connecting wires from the power supply. Thereafter, the grommet 100 is cooled for a predetermined time, and is waited for the grommet molding material to solidify. When the mold is opened, a grommet 100 integrated with the wire harness shown in FIG. 1D is obtained.

FIGS. 2 (A) and 2 (B) show P by the above manufacturing method.
FIG. 4 is a side view of the grommet 100 molded using the VC elastomer as viewed from the enlarged diameter portion 100A side and the reduced diameter portion 100B side, and there is no gap in the concave portion 12 between the adjacent electric wires of the four parallel electric wires w; The periphery of each electric wire w is completely filled with grommet (PVC elastomer).

Although the above embodiment has described a method of manufacturing a grommet integrated with a wire harness in which a plurality of electric wires are bundled in parallel, the present invention binds and bundles three or more electric wires vertically and horizontally. The present invention can also be applied to a case where a grommet integrated with a wire harness having a space between wires by a spacer is manufactured. That is, also in this case, the spacer insertion portion of the wire harness in which the spacer is inserted between the electric wires is set in a mold, the temperature of the wire harness is increased by energization, and the grommet is injection-molded. In this way, the molten grommet material can be maintained in the molten state without being cooled around the electric wire separated by the spacer, and can reliably cover the periphery of the electric wire, and can be integrated with the wire harness. It is possible to reliably manufacture a wire harness having no gap in the portion.

[0021]

As is apparent from the above description, according to the grommet manufacturing method of the present invention, since the temperature of the wire harness set in the mold is increased, the molten state of the molten state injected into the mold is increased. Even if the grommet material reaches the periphery of the wire of the wire harness, the molten state is maintained and the periphery of the wire is reliably covered, and as a result, the wire harness with no gap in the integrated part with the wire harness is securely formed. Can be manufactured.

[Brief description of the drawings]

FIGS. 1A, 1B, 1C, and 1D are schematic diagrams showing an embodiment of the present invention.

FIGS. 2A and 2B are side views of a grommet obtained by the manufacturing method of FIG.

FIG. 3 is a sectional view of a conventional grommet.

FIG. 4 is a diagram showing a gap formed between three adjacent electric wires of the wire harness.

FIG. 5 is a plan view of a spacer.

FIG. 6 is a cross-sectional view of a conventional grommet using a spacer.

FIG. 7 is a plan view (A) and a cross-sectional view (B) of a wire harness in which a plurality of electric wires are bundled in parallel and bound with an adhesive tape T.

[Explanation of symbols]

w Electric wire W / H Wire harness T Adhesive tape 12 Depression between electric wires 50 Grommet molding die 51 Mold part 61 Part to be integrated with grommet of wire harness (W / H) 62 Male connector 63A, 63B Male connector 70 Power supply 71 , 73A, 73B Connecting wires 72, 74A, 74B Female connector 100 Grommet 100A Large diameter portion 100B Large diameter portion

Claims (1)

[Claims] 1. A grommet manufacturing method for manufacturing a grommet integrally formed with a wire harness by injection molding, wherein a wire harness in which a portion to be integrated with the grommet is set in a grommet molding die is heated by energization. A method of manufacturing the grommet, comprising injecting and filling a mold material into the mold, and then releasing current from the wire harness to cool and solidify the mold material.