JPH0896653A - Method for manufacturing elastic material for keyboard switch - Google Patents

Abstract

(57) [Summary] [Purpose] To reduce the number of defective products when manufacturing elastic materials for keyboard switches with push-button parts made of thermoplastic elastomer. [Structure] By injecting a heated and melted thermoplastic elastomer into a molding die 10 for injection molding, a push button portion is formed through a thin elastic skirt-like elastic portion which is tapered integrally with a base plate portion. When molding the elastic material provided integrally, the base plate portion molding portion 11a of the molding die
And the push button portion molding portion 11b are provided with gate openings communicating with one or a plurality of gate sprues 12, respectively, and the thermoplastic elastomer is injected from the respective gate openings.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an elastic material for a keyboard switch used for a remote control device for a television set or an audio device, a calculator, and an operation part of a mobile phone or the like.

[0002]

2. Description of the Related Art Conventionally, as an elastic material for a keyboard switch of this kind, a thin elastic skirt-shaped returning elastic portion constituting a returning spring of a plurality of switches is integrally formed on a single base plate portion. For this reason, a structure in which a push button part is integrally provided on the top is known, and in recent years, a product manufactured by injection molding with a thermoplastic elastomer that does not require vulcanization has been developed ( (Kaisho 63-92428).

[0003]

In the conventional injection molding of this type of elastic material for keyboard switches, a gate opening is formed in the center of the lower surface of the push button molding portion in the mold, and molding is performed from the gate opening. Since the space in the mold is injected and filled, the thin skirt-shaped part that is the elastic part is not filled properly in many cases, resulting in poor product yield and high cost. .

Further, since it is necessary to make the injection into the skirt portion evenly, a gate opening is provided at the center of the bottom of the push button portion, so that a gate mark consisting of a small protrusion is formed at the switch contact portion on the bottom surface of the push button of the product. Since the remaining material must be removed, the conductive material for the movable contact member must be adhered, which increases the man-hours and the cost. The present invention has been made for the purpose of solving each of the above conventional problems.

[0005]

The feature of the present invention for solving the conventional problems as described above is that a thermoplastic elastomer which has been heated and melted is injected into a molding die for injection molding to form a base plate portion. In a method of manufacturing an elastic material for a keyboard switch, in which an elastic material integrally provided with a push button portion is formed via a thin skirt-shaped elastic portion for return, which is integrally formed with a base plate portion forming portion of the forming die. And one or a plurality of gate openings in the push button molding section, and thermoplastic elastomer is injected from each of the gate openings (Claim 1), and the base plate molding section and the push button molding section. Each gate opening of the above is opened to the convex portion bulged on the inner surface of each molding portion (claim 2).

[0006]

In the method of manufacturing an elastic material for a keyboard switch according to the present invention, since the molten elastomer is injected from both the base plate portion and the push button portion, the material is quickly filled and the thin elastic skirt portion which is the return elastic portion is filled. The material is always filled sufficiently and well, the number of defective products is small, and the product yield is improved.

Further, by providing the gate opening in the convex portion which is bulged in the mold, the molded product has a gate opening trace in the concave portion formed by the convex portion, and therefore, Since the gate opening does not project on the switch contact portion or the contact surface of the base plate portion with other members, the work for removing the gate opening is unnecessary.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings.

1 to 3 show an example of an elastic material produced by the method of the present invention. This elastic material is arranged so as to bulge to the upper surface side of the base plate portion 1 having a flat plate shape, and has a skirt-shaped elastic return portion 2 having a tapered upper portion.
A large number of push button portions 3 are provided in a predetermined arrangement via the.
In this elastic material, recesses 4, 4, ... Are formed in the bottom surface of the base plate portion 1 and the push button portion 3 in a predetermined arrangement, and small projection-shaped gate opening traces 5, 5 ... Are left in each recess portion 4. ing.

When manufacturing the elastic material as described above,
A mold 10 as shown in FIG. 4 is used.

This molding die 10 comprises a pair of dies 10a, 10
Each molding part, that is, the base plate part molding part 11a, the push button part molding part 11b, and the elastic part molding part 11c are continuously molded between b. Further, the gate sprue 12 for filling these molding portions with the thermoplastic elastomer is opened to communicate with the base plate portion molding portion 11a and the push button portion molding portion 11b respectively, and each of these gate sprues 12 has a gate port through which it communicates. An opening is formed in the protruding surface of the convex mold portion 13 that bulges into each of the molding portions 11a and 11b.

In the molding die 10 constructed in this manner, the gate sprues 12, 12 ... Are simultaneously or, if necessary, the base plate portion molding portion 11a and the push button portion molding portion 1.
A thermoplastic elastomer that has been heated and melted with a time lag with respect to 1b is injected and solidified by cooling with dies 10a and 10b to obtain a sheet-like elastic material for keyboard switches as shown in FIGS.

[0013]

As described above, according to the method for manufacturing an elastic material for a keyboard switch of the present invention, gate ports are provided in both the push button part forming part and the base plate part forming part in the forming die, and the thermoplastic elastomer is provided from each of them. By injecting, the molding of the skirt-shaped elastic portion between the base plate portion and the push button portion is always good, and the product yield is high,
Cost reduction can be achieved.

Further, since each gate opening is opened in the convex portion which is bulged in the molding portion, the gate opening mark remaining in the product is in the concave portion, so that it does not directly contact the contact portion or the substrate surface. No need for finishing work to remove the gate marks.

[Brief description of drawings]

FIG. 1 is a partial plan view of an example of an elastic material for a keyboard manufactured by the method of the present invention.

FIG. 2 is a vertical sectional view of the above.

FIG. 3 is a plan view of the above.

FIG. 4 is a partial cross-sectional view showing an example of a molding die used in the method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Base plate part 2 Elastic material for return 3 Push button part 4 Recessed part 5 Mark 10 Molds 10a, 10b Mold 11a Base plate part molded part 11b Push button part molded part 11c Elastic part molded part 12 Gate sprue 13 Convex part

Claims (2)

[Claims] 1. A push button part is formed by injecting a heated and melted thermoplastic elastomer into a molding die for injection molding, through a thin skirt-like elastic elastic part for tapering integrally with a base plate part. In a method of manufacturing an elastic material for a keyboard switch, which comprises integrally forming an elastic material, the base plate part molding part of the mold and the push button part molding part are provided with one or a plurality of gate openings, and each of the gate openings A method of manufacturing an elastic material for a keyboard switch, characterized in that a thermoplastic elastomer is injected from the material. 2. The elastic material for a keyboard switch according to claim 1, wherein each gate opening of the base plate portion molding portion and the push button portion molding portion is opened to a convex portion that bulges on the inner surface of each molding portion. Production method.