KR900004333B1 - Case moulding method of push-button - Google Patents

Abstract

A moulded case for a push-button switch comprises a contact plate (8) having a central fixed contact (2) and opposite fixed contacts (3), is made by (a) mounting the contact plate (8) between dies (11, 12) so that the contacts (2) and (3) bear against support portions (12b) and (12c) repsectively of the die (12), (b) pressing a locating pin (22) having a tapered end (22a) against the free face of the central contact (2), (c) injecting molten resin into the cavity (17) between the dies (11, 12) so as to mould the contacts into the switch body without allowing resin to penetrate between the contacts and their support positions, and (d) withdrawing the tapered locating pin (22) and leaving acentral tapered hole coming to a point which is small enough to prevent solder from flux entering around the central contact.

Description

Case forming method of push switch

1 is a cross-sectional view of the main portion showing the case forming method of the present invention.

2 is a cross-sectional view showing a state in which a push switch having a case molded by the method of the present invention is attached to a printed board.

3 is a cross-sectional view showing a state in which a conventional push switch is attached.

4 is a sectional view showing the main parts of a conventional molding method of a case.

5 is a cross-sectional view showing a state where a conventional fault contact is attached by a position fixing pin.

6 is a cross-sectional view showing a state in which a conventional push switch is attached to a printed board.

7 is a plan view showing the relationship between the fault contact and the case.

* Explanation of symbols for main parts of the drawings

1 case 2 center fixed contact

3: both sides fixed contact point 8: contact plate

11: upper fixed mold 12: lower movable mold

12b: Center fixed contact support 12c: Both sides fixed contact support

22: positioning pin

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to push switches used in various input devices such as TVs, VTRs, cassette techs, and the like, and more particularly, to an improvement in a method of forming a case of a push switch.

A conventional method for forming a case of a push switch will be described with reference to FIGS. 3 to 6.

First, FIG. 3 shows a push switch of this type, where 1 is a case made of synthetic resin, and the center fixed contact point (2) and both fixed contact points (3) are formed on the bottom of the case (1) by insert molding. The terminals 4 extending from the fixed contacts 2 and 3 protrude from the sides of the case toward the bottom of the case. Then, a movable contact 5 is disposed on both side fixed contacts 3, and a stem 6 having movable contact pressing projections 6a is disposed on the movable contact 5, respectively. The presser plate 7 of the shape is configured to suppress the upward movement of the stem 6. When the case 1 of the push switch is formed, as shown in FIG. 4, the hoop-shaped contact plate 8 having the central fixed contact 2 and the both fixed contacts 3 is provided with the upper fixed mold 11. It is disposed between the lower and the movable mold (12), the polyethylene terephthalate (PET) or polybutylene terephthalate (PBT) dissolved in the molding machine 13 after assembling the upper and lower molds (11) (12) The cavity 17 between the upper and lower molds 11 and 12 from the submarine gate 16 formed at the horizontal position of the lower movable mold 12 through the spun 14 and the runner 15. It was molded by injection. However, in the forming method, the fixed contact points 2 and 3 are only mounted on the support parts 12b and 12c on the protruding block 12a of the lower movable mold 12. It is easy to create a gap between 12b) and 12c, and when resin penetrates between the fixed contacts 2, 3 and the support parts 12b, 12c, resin is formed on the fixed contacts 2, 3; There was a problem of coating, causing contact failure when used as a switch.

Here, as shown in FIG. 5, the positioning pin 19 is bent from the upper movable mold 11 toward the center stationary contact point 2, and the positioning pins are planar on the both sides of the stationary contact point 3. 20) are faced to each other, and the case 1 is molded so that the fixed contacts 2 and 3 are pressed onto the lower movable mold 12 so that the resin is not coated on the fixed contacts 2 and 3.

However, in the conventional molding method, in order to prevent a gap between the fixed contact points 2 and 3 and the lower movable mold l2, the fixed contact positioning pins 19 and 20 are removed from the upper fixed mold 11 side. The pins 19 and 20 are positioned to fix the fixed contacts 2 and 3 by protruding. However, since the pins 19 and 20 are formed in a cylindrical shape, the case 1 is attached to the contact pin 8. ) Was formed, and then, as shown in FIG. 6, the pin extraction hole la 1b was formed between the bottom face of the case 1 and the fixed contact point 2,3.

Therefore, when the terminal 4 is soldered to the printed circuit board 21 as a push switch, there is almost no problem when soldering by hand, but in the case of automatic soldering, the flux for solder blowing from the lower surface in the ejected state is In the hole 1a of the case 1 which is opened by the positioning pin 20 for supporting the both side fixed contacts 3 through the terminal 21a of the printed board 21, sometimes the center fixed contact 2 is supported. It penetrates into the hole 1b of the case 1 opened by the dragon positioning pin 19, which causes the flux to pass through the minute gap between the case 1 and the fixed contact 2,3. There is a problem that it rises and adheres on the fixed contact (2) (3), worsens the conductivity between the fixed contact (2) (3) and the movable contact (4), causing contact failure.

Therefore, an object of the present invention is to solve the above technical problem and to obtain a method for forming a case that can prevent contact failure of a contact.

The present invention for solving the above technical problem is to place a contact plate having a central fixed contact and both sides of the fixed contact between the upper mold and the lower mold and the injection switch for molding the case by injecting molten resin in the cavity between the upper and lower molds In the case forming method, the shape of the both sides fixed contact support of the one mold for joining the both sides fixed contact is formed approximately equal to the outer shape of the both sides fixed contact, and the other mold is formed on the center fixed contact support for the center fixed contact. The positioning pin, which is raised from the side and ends at the end, is pushed to position the center of the central fixed contact.

Therefore, in the present invention, the mold shape is formed so that the external shape of both the fixed contact point and the both sides fixed contact support of the mold is approximately equal, and the positioning pins having the shape of the end of the tip are pressed onto the center fixed contact point, At the time of molding, the center fixed contact point and both fixed contact points are in close contact with the upper and lower mold surfaces, and the molten resin does not invade between the center fixed contact point and the mold or both fixed contact points and the mold. . When the push switch using this case is automatically soldered to the printed board, the flux does not enter the contact portion.

Hereinafter, the present invention will be described with reference to the drawings.

1 is an enlarged cross-sectional view showing main parts showing a method of forming a case;

2 is a cross-sectional view of a push switch having a case molded by the method of the present invention.

In the present embodiment, the same parts as in the prior art are denoted by the same reference numerals and redundant description thereof will be omitted. In the drawings, the contact plate 8 having the center stationary contact point 2 and the two stationary contact points 3 is disposed between the upper stationary mold 11 and the lower movable mold 12, but the present invention is the same. The feature is the following configuration.

That is, the mold shape of the both sides fixed contact support part 12c of the lower movable mold 12 which mounts the both sides fixed contact point 3 is formed to be substantially the same as the shape of the both sides fixed contact point 3, and the center fault contact point 2 is formed. The tip end portion 22a of the positioning plate 22 is pressed into a center tapered contact portion 12b in a tapered shape.

When the molten resin is injected into the cavity between the upper fixing mold 11 and the lower movable mold 12 under the above constitution, the central fixed contact point 2 protrudes from the upper fixing mold 11 side and the tip end portion 22a. Of the lower movable mold 12 is firmly pressed against the fixed contact supporting portion 12b of the lower movable mold 12 by the positioning pin 22 having a tapered shape, and the two fixed contacts 3 are connected to both fixed contacts ( 3) and the external dimensions are joined to both sides of the fixed contact support portion 12c approximately equal in size, so that the resin does not invade between the fixed contact 2 (3) and the lower movable mold 12.

In the case where the terminal 4 is soldered to the printed circuit board 21 after assembling the push switch shown in FIG. 2 using the case 1 formed by the above method, positioning at the time of forming the case 1 is performed. Although the hole 1c of the lower surface of the center fixed contact 2 according to the shape of the tip part 22a of the pin 22 is formed, the contact part of this hole 1c and the center fixed contact 2 becomes extremely small diameter. Therefore, the flux does not enter the central fixed contact point 2 through this hole 1c. Then, when the push switch is operated, the stem 6 is moved downward to bend the movable contact 5 of the curved shape while the stem 6 is moved downward, whereby the center fixed contact 2 and both fixed contacts (3) is conducted through the movable contact (5). At this time, since no resin or flux is attached on the fixed contacts 2 and 3, the switching operation of the push switch is extremely good. Further, in the above embodiment, the contact plate 8 is configured to abut on the lower movable mold 12, but is not limited thereto, and may be configured to abut on the upper fixing mold side.

As described above, the present invention forms the shape of both sides of the fixed contact support of the mold for contacting both sides of the fixed contact with the external shape of the two sides of the fixed contact, and the position of the tip of the tip is tapered on the center fixed contact. When the case is molded by pressing the pin, the molten resin does not penetrate between the center fixed contact point and the mold or between both sides of the fixed contact point and the mold, and the contact part is used when the push switch using the case is automatically soldered to the printed board. Flux does not break in, either. Therefore, contact failure of the push switch can be prevented and a highly reliable push switch can be obtained.

Claims (1)

A case of a push switch case forming method, wherein a contact plate having a center fixed contact point and two fixed sides is disposed between an upper mold and a lower mold, and a molten resin is injected into the cavity between the upper and lower molds to form a case. The shape of both fixed contact support parts of one mold contacting the contact is formed to be equal to the external shape of both fixed contact points, and protruding from the other mold side on the center fixed contact support part contacting the center fixed contact point, the tip end thereof A method of forming a case of a push switch, wherein the tapered positioning pin is pressed to position a central portion of a center fixed contact point.

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