JP2905983B2 - Forming method of push button switch - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a push button switch having a conductive portion on the inner upper part of a hollow mesa-shaped (reversely-shaped) elastic body.

"Prior art" The push-button switch has a known example such as Japanese Patent Application Laid-Open No. 64-3930 and Japanese Utility Model Application Laid-open No. 63-18727, and as shown in FIG. 4, is made of an elastic material such as silicone rubber. A conductive portion 2 made of a conductive material is integrally formed downward on an inner upper portion of an insulating hollow mesa-shaped elastic body 1. And the conductive portion 2 are brought into contact with each other.

The push-button switch is mass-produced by injection molding using a molding die, and includes a fixed die 7 and a movable die 8 joined at a part line 6 as shown in FIG. 5 (A). The movable mold 8 having the elastic cavities 9 of the elastic body 1 except for the elastic mold 2 is an elastic injection gate of the fixed mold 7.
The elastic body 1 is primarily formed by joining with the portion 11A.

Subsequently, after cooling and solidifying the elastic body 1 by the primary molding described above, the elastic body 1 of the primary molding was molded and mounted on the portion of the fixed die 7 having the conductive part cavity 10 of the conductive part 2 and the conductive part injection gate 11B. The movable die 8 is rotated or slid and joined as shown in FIG. 5 (B) to form the injection gate 11B.
The conductive part 2 is secondary-formed by injection from the mold, and after the conductive part 2 is cooled and solidified, the fixed die 7 and the movable die 8 are separated and released, and a push button switch having a required shape is formed.

[Problem to be Solved by the Invention] The push button switch of the above-mentioned known example has a structure in which the conductive portion 2 is integrally protruded inside the hollow mesa-shaped elastic body 1, and therefore, when performing injection molding with a molding die, the fifth portion is required. As shown in the drawing, the injection gate 11 has to be set on the lower surface of the conductive portion 2, and thus the lower surface of the formed conductive portion 2, that is, the flat contact surface 5 of the conductive portion 2 is formed.
Existing protrusions 4 based on the injection gate 11 are generated, and the remaining protrusions 4 become harmful substances, which easily cause poor contact between the conductive portion 2 and the contact 12, and it is necessary to remove the remaining protrusions 4 in order to prevent it. As a result, there is a problem that the unnecessary removal process increases and the cost increases.

Further, the push button switch having the conventional structure has a structure in which the conductive portion 2 is provided on the inner upper portion of the hollow elastic mesa-shaped insulating elastic body 1 to form an integral body. The primary molding and the secondary molding are required, and the primary molding and the secondary molding have to adopt a method of forming by rotating or sliding the movable die 8. A moving mechanism, a moving space, and a moving time are required, and the molding apparatus is inevitably complicated and large in size, resulting in high cost. In addition, there are disadvantages such as a long molding interval and impairing molding productivity.

The present invention provides a method of forming a push button switch that solves the above-mentioned drawbacks of the conventional means.

"Means for solving the problem" The present invention for solving the above technical problem "provides a vertically penetrating tubular portion at the center of a hollow mesa-shaped elastic body, and in the tubular portion,
In forming a push button switch having a structure in which a columnar conductive portion having a flat contact surface facing downward is integrally inserted and penetrated, joining is performed at a part line, and a molding cavity of the push button switch is unitedly formed at the joint portion. One mating type having an inner edge of the cavity and a columnar conductive portion cavity, and a retractable rod that makes the columnar conductive portion cavity a solid or empty space is attached and retracted freely, and an outer edge of the elastic body cavity. Using an injection mold consisting of an injection gate of an elastic body and the other mating mold having an injection gate of a columnar conductive part, the elastic body is primarily formed by making the columnar conductive part cavity solid by advancement of the advance / retreat rod. Thereafter, the column-shaped conductive portion cavity is made vacant by the advance / retreat of the rod, and the column-shaped conductive portion is formed into a secondary shape. It has become the molding method "of the switch.

[Operation] According to the above-described method of forming a push button switch of the present invention, an injection gate for injection-molding a column-shaped conductive portion extending vertically is provided above the conductive portion (outside the elastic body). ), The molding can be performed, so that the remaining protrusion based on the injection gate does not occur on the contact surface with the contact.
And, while joining a pair of mating molds at the part line,
By moving the reciprocating rod in the molding die, it is possible to form a "push button switch in which a columnar conductive portion is integrally inserted into a tubular portion of a hollow Mesa-shaped elastic body", which is a simpler method than the conventional molding method. And can be molded by the equipment.

"Example" Hereinafter, a detailed description will be given based on an example. First, the structure of a push button switch formed by the forming method of the present invention will be described with reference to FIGS. That is, in a push button switch having a conductive portion on the inner upper portion of a hollow mesa-shaped elastic body 1 with a flat adhesive surface 5 facing downward, the one shown in FIG. A cylindrical columnar conductive portion 2 is integrally formed on the cylindrical portion 15. The lower end surface of the elastic body 1 extends through the hollow portion of the elastic body 1 so as to form a flat contact surface 5.
Further, the lower end of the columnar conductive portion 2 of this embodiment slightly protrudes from the lower end of the cylindrical portion 15, and the lower end of the cylindrical portion 15 forms a step 16.

The one shown in FIG. 2 is a cylindrical part 15 penetrating vertically.
The columnar conductive portion 2 is integrally inserted, and the cylindrical portion of the cylindrical portion 15 is omitted only inside the elastic body 1, and the columnar conductive portion 2 is exposed inside the elastic body 1 and is vertically suspended. ing.

An embodiment of the method of forming the push button switch shown in FIGS. 1 and 2 will be described with reference to FIG. In other words, the molding die used in this molding method is, as shown in FIG. 3 (A), joined at the part line 6 to form a push-button molding cavity at the joint site “the inner edge 20 of the elastic cavity and the column-shaped conductive portion cavity”. One of the mating molds 18A having the tee 10 "and the other mating mold 18B having the outer edge 21 of the elastic body 1, the ejection gate 11A of the elastic body, and the ejection gate 11B of the columnar conductive portion 2". In the mating die 18A, the column-shaped conductive portion cavity 10 is attached to the column-shaped conductive portion cavity 10 so as to be able to advance and retreat, and the column-shaped conductive portion cavity 10 is solid at the front dead center position, and the column-shaped conductive portion cavity 10 is vacated at the rear dead center position. A reciprocating rod 19 is mounted. In the drawing, 13 is an injection runner groove, 14
Is an injection nozzle.

Then, the above-mentioned mating dies 18A18B are united and fixed at part line 6, and refer to FIG. 3 (B).
19 is stopped at the front dead center, the columnar conductive portion cavities 10 are closed and filled, and a molten material is injected from the injection gate 11A of the elastic body 1 to form the elastic body 1 in a first order. Subsequently, after the elastic body 1 is cooled and solidified, as shown in FIG. 3 (C), the advancing / retracting rod 19 is retracted to the rear dead center position to make the columnar conductive portion cavity 10 empty, and the columnar conductive portion 2 is injected. A molten material is injected from the gate 11B to secondarily form the columnar conductive portion 2. After the columnar conductive portion 2 is solidified, the mating dies 18A and 18B are opened, and the formed push button switch shown in the first drawing is taken out.

The molding method according to the above-described embodiment has the above-described effect, and the push-button switch can be injection-molded while the pair of mating dies are united and set.

The elastic body 1 of the push button switch according to the molding method of the present invention is formed of a thermoplastic elastomer or a thermosetting rubber having injection moldability, and the columnar conductive portion 2 is formed.
Is made of a thermoplastic elastomer which is made to be able to adhere to the elastic body 1 by injection molding and is made conductive by adding carbon powder or metal powder, or a thermosetting rubber having injection moldability.

[Effects of the Invention] As described above, in the push button switch according to the molding method of the present invention, a harmful residual protrusion based on the injection gate does not exist on the contact surface side of the columnar conductive portion, so that a good switch mechanism is stabilized. At the same time, since the operation of removing the remaining protrusions becomes unnecessary, there is an effect that the process of forming the push button switch is simplified and the cost is reduced.

Further, since the molding method of the present invention can perform molding with the set of a pair of mating dies fixed, the moving space of the forming die and the moving mechanism of the dies in the conventional means are unnecessary, and the forming apparatus is much smaller than the conventional one ( In addition to being approximately 1/2), there is an effect of improving the molding productivity of the push button switch and reducing the molding cost.

[Brief description of the drawings]

FIG. 1 shows a push button switch according to the molding method of the present invention,
(A) is a front view thereof, (B) is a bottom view thereof, and FIG. 2: a front view of another push button switch according to the molding method of the present invention, and FIG.
FIG. 1 shows an embodiment of a method of forming a push button switch according to the present invention, in which (A) is a front view of a main part of a forming die, (B) and (C) are front views showing an operation state thereof, and FIG. Front view of push button switch having structure, FIGS. 5 (A) and 5 (B): Front view showing molding method of push button switch of conventional structure Main symbols: 1: elastic body, 2: conductive part, 4: residual protrusion, 5 : Flat contact surface, 6: Part line, 7: Fixed type, 8: Moving type, 9: Elasticity cavity, 10: Columnar conductive cavity, 11A11B: Injection gate, 12: Contact point, 15: Cylindrical portion, 18A18B: Mating type, 19: retraction rod

Claims (1)

(57) [Claims] 1. A hollow mesa-shaped elastic body is provided with a vertically penetrating tubular portion at the center thereof, and a columnar conductive portion having a flat contact surface facing downward is integrally inserted into and penetrated into the tubular portion. In forming the push button switch, the part line is joined together, and the joining cavities are combined to form the molding cavity of the push button switch.``The inner edge of the elastic body cavity and the columnar conductive portion cavity are provided, and the columnar conductive portion cavity is formed. From one mating type with a retractable rod attached to a solid or empty space so as to be able to move forward and backward, and from the other mating type having an outer edge of an elastic body cavity, an elastic injection gate, and an injection gate of a columnar conductive part. The elastic body is primarily formed by making the columnar conductive portion cavity solid by the advancement of the advance / retreat rod, and thereafter, the columnar conductive member is retracted by the retreat of the advance / retreat rod. Molding method of push button switch, characterized in that forms a part Kiyabiti the cavity for molding the secondary of the columnar conductive part.