JP2947205B2 - Method of forming grommet with bellows - 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 forming a grommet with a bellows portion for use in protecting electric wiring of an automobile or an electric device. The present invention relates to a method of forming a grommet with a bellows portion, which is connected to and fixed to both ends of a vehicle body and a vehicle body door, and which expands and contracts by opening and closing the vehicle body door by an intermediate bellows portion.

[0002]

2. Description of the Related Art Referring to FIG. 2, a conventional grommet with a bellows is formed of an elastic tube having connection portions 3 and the like at both ends for connecting to equipment such as a vehicle body, and several unit bellows 2 are connected at an intermediate portion. A bellows portion 1 is provided, and has a structure for storing and protecting electric wiring such as a wire harness in a hollow portion thereof, and a unit bellows portion 2 constituting the bellows portion 1 is orthogonal to the tube center line. With respect to the vertical center line 5 passing through the vertex 7 of the unit bellows 2, two sloping portions 6 connected to the vertex 7 are formed by symmetric inclined portions forming a symmetric shape.

The above grommet with a bellows is
Referring to FIG. 3, a mating mold 10 having an outer peripheral shape of a grommet to be manufactured, and a core mold 11 having an inner peripheral shape of a grommet to be manufactured and inserted into the cavity of the molding die 10 are used. This is a manufacturing method in which a rubber material is filled in a gap between the molding die 10 and the core die 11 and molded.

[0004]

The above-mentioned conventional grommet with a bellows portion is a symmetrical slope portion 6 in which the pitch P of the unit bellows portion 2 necessary for expansion and contraction of the bellows portion 1 is split.
The slope 6 has a shape with a considerably steep slope. Therefore,
After the grommet is manufactured, even if the core mold 11 is pulled out with the mold 10 removed, the pull-out resistance due to the slope portion 6 is so large that the core assembly 11 and the core mold 11 cannot be pulled out.
The bellows portion 1 is enlarged by pressurizing the bellows portion 1 and the core mold 11 is pulled out in this state as shown by the arrow A in the drawing, which reduces the complexity and cost of the grommet manufacturing process. There is a defect that brings. The present invention provides a method of forming a grommet with a bellows, which solves the above-mentioned disadvantages of the prior art.

[0005]

A method of forming a grommet with a bellows according to the present invention, which solves the above technical problem, includes a method of forming a grommet with a bellows comprising a plurality of unit bellows having slopes on both sides of a vertex. In forming a grommet with a bellows portion provided in the middle of the property pipe, "one side of the slope portion is a gentle slope portion.
The other side is a steep slope section, and the unit angle section of the asymmetric slope section centered on the vertical center line passing through the vertex is expanded in the middle of the rod-shaped core body with the gentle slope section in the same direction. The core molds connected and connected to each other are set in the mold of the mating mold by insert-setting to set a molding cavity between the molding mold and the core mold, and a rubber material is injected and filled into the molding cavity. A grommet with a core type is formed, and thereafter, the grommet and the core type are separated by pulling out the core type with the core type grommet in the direction of the gentle slope portion side. Method of forming grommet with bellows ".

[0006]

According to the method of forming a grommet with a bellows portion of the present invention having the above-mentioned structure, the core mold to be insert-set in the mating mold is provided with the asymmetrical slope portion composed of the gentle slope portion and the steep slope portion. The grommet molded by using the core mold has a shape in which the unit angle-shaped portions in which the gentle slope portions are arranged in the same direction and are juxtaposed to the rod-shaped core main body are juxtaposed.
The grommet with the bellows portion can be formed by connecting the unit chevron portion and the unit bellows portion having a similar asymmetric shape.

[0007] Then, after removing the grommet with the core type, in which the formed grommet is covered by the core type, from the mating die, grasping the end of the core type, the gently inclined surface side When a pulling force is applied in the direction of, a large slipping component force is generated between the outer periphery of the core mold in the joined state and the gentle slope of the grommet, based on the gentle slope angle of the gentle slope, and the gentle slope Is made elastic and deforms to avoid external force outward, so that the core mold can be easily pulled out as it is to separate the molded grommet and the core mold.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a detailed description will be given based on embodiments. In this embodiment, a grommet 20 with a bellows portion is attached and fixed between a vehicle body and a vehicle body door to store and protect a wire harness in a hollow portion, and is formed at an intermediate portion of an elastic hollow tube body. The provided bellows portion 1 is constituted by a continuous arrangement of unit bellows portions 2 having an asymmetric shape described below.

That is, the unit bellows portion 2 is formed by a gentle slope portion 8 on one side of the vertex 7 and a steep slope portion 9 on the other side, and a required bellows expansion and contraction is made between the gentle slope portion 8 and the lower end of the steep slope portion 9. The unit bellows pitch P is satisfied.
Represents a slope having a gentle slope angle acceptable within the pitch P, and the steep slope portion 9 forms a slope having a steep slope angle that is nearly vertical.

The above-mentioned unit bellows 2 group is arranged side by side with the gentle slope 8 in the same direction.
The lower end of the gentle slope portion 8 and the lower end of the steep slope portion 9 are joined and integrally connected to form the bellows portion 1. That is, this bellows part 1
Is a unit bellows 2 passing through the vertex 7
A pair of slope portions 8 and 9 on both sides of the vertex 7 have an asymmetric shape with the vertical center line 5 as an axis.

The above-described grommet 20 with a bellows is formed by the following method and procedure. That is, first, the core mold 11 used in this forming method has a shape in which unit angle portions 13 are arranged in a row at key points of a rod-shaped core body 12, and the unit angle portions 13 Has a gentle slope 8 on one side and a steep slope 9 on the other side, and has an asymmetric shape with the center line 5 passing through the apex 7 as an axis, and an arbitrary number of unit mountain portions 13 (four in the figure). It has a shape similar to the bellows portion 1 of the grommet 20 and is in a shape inscribed in the bellows portion 1 and is a bellows forming core portion 14 for forming the bellows portion 1.

Then, the above-mentioned core mold 11 is inserted into a well-known mating mold 10, and a molding cavity 15 having a thin gap corresponding to the rubber thickness of the grommet 20 is set around the core mold 11. . Subsequently, in this state, the molten rubber material 16 is injected and filled into the molding cavity 15 and solidified, and the hollow mold 11 is detached from the molding mold 10 and the core mold 11 is removed.
The grommet-equipped core 17 in a form in which the grommet 20 is covered is taken out.

After that, the core type 1 with grommet
The core mold 11 is pulled toward the gentle slope portion 8 in the direction of arrow A in the figure to separate the core mold 11 and the grommet 20 to form a grommet 20 with a bellows portion.

Since the grommet 20 formed by the above embodiment uses the core mold 11 having the bellows forming core portion 14, the grommet 20 is formed into a grommet with a bellows portion having a predetermined shape, and the core is formed by the above-described operation. The separation of the mold 11 and the grommet 20 can be made extremely simple and efficient.

[0015]

As described above, according to the method for forming a grommet with a bellows portion of the present invention, after molding with a mold with a core, the molded grommet is not enlarged and the core is formed immediately after molding. Since the mold can be pulled out,
The grommet molding process is simplified and streamlined, and the conventional enormous equipment is not required, which has the effect of reducing the grommet molding cost.

[Brief description of the drawings]

FIG. 1 is a front view showing a method and procedure of a method for forming a grommet with a bellows portion according to an embodiment of the present invention.

FIG. 2 is a front view of a conventional grommet with a bellows.

FIG. 3 is an explanatory view showing a conventional means for forming a grommet with a bellows portion and a state in which a core mold is removed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bellows part 2 Unit bellows part 3 Connection part 5 Vertical center line of unit bellows part 6 Slope part 7 Apex 8 Slow slope part 9 Steep slope part 10 Mold 11 Core type 12 Core body 13 Unit chevron part 14 Bellows forming core Part 15 Molding cavity 17 Grommet with core 20 Grommet with bellows

Claims (1)

(57) [Claims] In forming a grommet with a bellows portion provided in the middle of an elastic tubular body, a bellows portion formed of a series of unit bellows portions having a slope portion on both sides of an apex is formed on one side of the slope portion. Into a gentle slope and the other side as a steep slope '', a unitary chevron with an asymmetrical slope centered on the vertical center line passing through the vertex, and the gentle slope in the middle of the rod-shaped core body. The core mold swelled and connected in the same direction is insert-set in a mating mold, a molding cavity is set between the molding mold and the core mold, and a rubber material is formed on the molding cavity. To form a grommet with a core, and thereafter, by pulling out the core of the grommet with the core in the direction of the gentle slope, the grommet and the core are separated. A method for forming a grommet with a bellows portion, characterized in that: