MANUFACTURING METHOD OF PUSH-BUTTON SWITCH

• US 20120227251A1
• Filed: 07/21/2011
• Published: 09/13/2012
• Est. Priority Date: 07/23/2010
• Status: Active Grant

• Current Assignee: Shin-Etsu Polymer Company Limited (Shin-Etsu Chemical Company Limited)
• Original Assignee: Shin-Etsu Polymer Company Limited (Shin-Etsu Chemical Company Limited)
• Inventors: Suzuki, Norio, Fukuda, Keiichi, Hyuga, Shunta, Miyamura, Haruaki
• Granted Patent: US 8,695,211 B2
• Time in Patent Office: Days
• US Class Current: 29/622
• CPC Class Codes: B29C 45/14467 Joining articles or parts of a single article B29C45/14377, B29C45/14385, B29C45/14581, B29C45/14614 and B29C45/006 take precedence
• CPC Class Codes: B29K 2083/005 LSR, i.e. liquid silicone rubbers, or derivatives thereof
• CPC Class Codes: H01H 13/063 Casings hermetically closed by a diaphragm through which passes an actuating member vacuum switches H01H33/66
• CPC Class Codes: H01H 13/88 Processes specially adapted for manufacture of rectilinearly movable switches having a plurality of operating members associated with different sets of contacts, e.g. keyboards
• CPC Class Codes: H01H 2223/002 sealed
• CPC Class Codes: H01H 2229/044 Injection moulding
• CPC Class Codes: H01H 2229/048 Insertion moulding
• CPC Class Codes: Y10T 29/49105 Switch making
• CPC Class Codes: Y10T 29/4998 Combined manufacture including applying or shaping of fluent material

Abstract

In a manufacturing method of a push-button switch, a key-top end of a pressing element 25 is inserted into a lower-mold recess for the pressing element, which is provided in a surface of a lower mold. A reinforcing plate 28 is placed in the lower mold so that the pressing element 25 extends through a plate through hole of the reinforcing plate 28. An upper mold and the lower mold are moved toward each other so as to insert the other end of the pressing element 25 into an upper-mold recess for the pressing element, which is provided in a lower surface of the upper mold. A liquid silicone rubber 27, which contains a component that does not adhere to the upper and lower molds but adheres to the pressing element 25, is introduced into a cavity. After the upper and lower molds are pressed and held at a predetermined temperature for a predetermined time, the upper and lower molds are opened to remove a molded product in which an intermediate portion in an axial direction of the pressing element 25 is supported in the plate through hole by the silicone rubber 27. A back surface of a key top 26 is attached to the key-top end of the pressing element 25 in the molded product. Thus, the pressing element and the elastic member are easily and reliably integrally molded by using the elastic member, and durability of the push-button switch is improved.

Claims

1. A manufacturing method of a push-button switch, comprising:

a preparation step of preparing a key top, a pressing element that is attached to a back surface of the key top, and a reinforcing plate having a plate through hole that is larger than an outer periphery of the pressing element;

a pressing-element insertion step of inserting one end in an axial direction of the pressing element into a lower-mold recess for the pressing element, which is provided in a surface of a lower mold;

a reinforcing plate placing step of placing the reinforcing plate in the lower mold so that the pressing element extends through the plate through hole of the reinforcing plate;

a mold clamping step of moving an upper mold and the lower mold toward each other so as to insert the other end of the pressing element into an upper-mold recess for the pressing element, which is provided in a lower surface of the upper mold;

an introducing step of introducing an elastic member, which contains a component that does not adhere to the upper and lower molds but adheres to the pressing element, into a cavity formed between the upper and lower molds;

a molding step of, after the introducing step, pressing and holding the upper and lower molds at a predetermined temperature for a predetermined time, and then opening the upper and lower molds to remove a molded product in which an intermediate portion in the axial direction of the pressing element is supported in the plate through hole by the elastic member; and

an attaching step of attaching the back surface of the key top to the one end of the pressing element in the molded product.

2. The manufacturing method of claim 1, wherein

the reinforcing plate is comprised of a metal, and has been subjected to a nitriding treatment.

3. The manufacturing method of claim 2, wherein

the reinforcing plate has been subjected to a primer treatment that increases adhesion between a surface of the reinforcing plate after the nitriding treatment and the elastic member.

4. The manufacturing method of claim 1, wherein

the pressing element is comprised of a thermoplastic resin, and

in the molding step, molding is performed at a temperature that is not high enough to melt the pressing element.

5. The manufacturing method of claim 4, wherein

the pressing element is comprised of polycarbonate, and

the elastic member is comprised of silicone rubber that chemically bonds with the polycarbonate in the molding step.

6. The manufacturing method of claim 1, wherein

the one end and the other end of the pressing element have a circular cross section, and are tapered so that an outer diameter of each of the ends is gradually reduced toward outside,

at least one of the lower-mold recess for the pressing element and the upper-mold recess for the pressing element has a circular cross section, and is recessed so that its inner diameter decreases stepwise at two or more positions, and

the outer periphery of the pressing element contacts each of a plurality of corners where the inner diameter decreases stepwise, and prevents the elastic member from flowing onto the outer periphery of the pressing element.

7. The manufacturing method of claim 1, wherein

a surface roughening treatment is performed before the molding step on a portion of the pressing element, to which the elastic member is to adhere.

8. The manufacturing method of claim 1, wherein

the pressing element is heat-treated before the molding step at a temperature equal to or higher than the predetermined temperature of the molding step.

9. The manufacturing method of claim 1, wherein

a constant distance is maintained between an upper surface of the reinforcing plate and the lower surface of the upper mold by at least a pair of retaining pins, which are provided on the lower surface of the upper mold to retain the reinforcing plate.