JPH0628947A - Push-button switch and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide a push-button switch by which cost can be reduced significantly without deteriorating reliability and positional accuracy on a fixed contact point can be heightened and downsizing can be promoted by using a round wire rod as a base material of the fixed contact point and a terminal, heightening installation strength of the round wire rod, and carrying out working so that even positional dislocation in a cavity can be prevented. CONSTITUTION:A projecting part 7a being formed by deflecting a diameter of a round wire rod 7 in a cavity when clamping is carried out in an insert molding process, is exposed on the inside bottom surface 1a of an insulating case 1, and a fixed contact point 2 is formed. At the same time, the bottom part of the projecting part 7a is buried in the insulating case 1, and the round wire rod 7 projecting outward from the insulating case 1 is also formed as a terminal 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small push button switch suitable for automatic mounting and a method for manufacturing the same.

[0002]

2. Description of the Related Art Generally, a push-button switch of this type has an insulating case made of synthetic resin and formed in a cylindrical shape having a bottom, and a pair of fixed contacts made of metal plates exposed on the inner bottom surface of the insulating case. The terminal is made of a metal plate that is led out from each fixed contact and projects to the outside of the insulating case, and a movable contact that is incorporated in the insulating case and is capable of contacting and separating from both fixed contacts is provided. An insert in which a pair of strip-shaped metal plates that form a convex bent portion and extend substantially in parallel are inserted into a cavity of an insulating case molding die, and molten resin is filled in the cavity to cool and solidify. By performing the molding, the bent portions of the strip-shaped metal plates serve as fixed contacts, and the strip-shaped metal plates protruding outside the insulating case serve as terminals.

In the push button switch, when a pressing drive force is applied to a movable contact facing the inner bottom surface of the insulating case to bring it into contact with both fixed contacts, both fixed contacts are brought into conduction via the movable contact to switch on. When the switch is switched to the state and the pressing driving force is removed, the movable contact automatically returns to the initial position and returns to the switch-off state. For example, a dome-shaped reversing spring is used as the moving contact. A push button switch configured to be pressed by a stem is widely known.

[0004] In such a small push button switch, a long tape called a carrier tape is used to carry the terminals, so that a large number of them can be efficiently stored / stored in a batch, and an automatic mounting machine at the time of mounting. By chucking and separating from the carrier tape, automatic mounting at a predetermined position on the printed circuit board can be easily performed.

[0005]

However, in the above-mentioned conventional push button switch, since the strip-shaped metal plate on which the bent portion for the fixed contact is previously formed has to be supplied to the mold, the bent portion of the bent portion in the cavity has to be supplied. Positional deviation easily occurs, which makes it difficult to improve the positional accuracy of the fixed contacts and promote downsizing of the push button switch. Also,
When disconnecting this type of push button switch from the carrier tape or attaching it to the printed circuit board, the terminal is cut using a lead cutter or a cut and clinch blade. Since it cannot be cut without applying force, the blade is heavily worn in the step of cutting the terminal, in other words, the life of the blade is short, which causes the cost increase of the push button switch.

Therefore, it is conceivable to use a round wire material, which is easy to cut and is low in material cost, as a metal member forming a fixed contact and a terminal, instead of a strip-shaped metal plate. It was difficult to secure high reliability because sufficient rounding strength could not be obtained even when the above was molded, and the round wire rod might rotate or come off from the insulating case.

The present invention has been made in view of the problems of the prior art as described above, and a first object thereof is to significantly reduce the cost without impairing the reliability and to improve the positional accuracy of the fixed contact. It is an object of the present invention to provide a push button switch that can be reduced in size, and a second object of the present invention is to provide a method of manufacturing such a push button switch.

[0008]

In order to achieve the first object, in the present invention, instead of a strip-shaped metal plate, a ridged portion that is subjected to uneven thickness processing and is exposed on the inner bottom surface of the insulating case is provided. A round wire is used, and the raised portion of the round wire serves as a fixed contact, and the bottom of the raised portion is embedded in an insulating case.

In order to achieve the second object,
The present invention allows the movable pin to enter the cavity of the mold,
By inserting a round wire rod into the cavity and clamping the die, a portion of the round wire rod sandwiched between the movable pin and the cavity wall surface facing the movable pin is unevenly formed into a raised portion, and then the movable rod is moved. The pins were moved out of the cavity, and then the cavity was filled with a molten resin to be cooled and solidified to form an insulating case, and the raised portion was exposed on the inner bottom surface of the insulating case.

[0010]

[Operation] When insert molding is performed so that the bottom of the raised portion formed by eccentricizing the round wire rod is buried in the insulating case,
The rotation preventing strength and the retaining strength of the round wire rod with respect to the insulating case are increased to improve the reliability, and the raised portion can be formed by eccentricizing the round wire rod in the cavity during mold clamping in the insert molding step. Therefore, there is no possibility that the raised portion will be displaced in the cavity, the positional accuracy of the fixed contact is improved, and the number of steps can be reduced.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

1 to 8 relate to a first embodiment of the present invention. FIG. 1 is a sectional view of a push button switch, FIG. 2 is a sectional view of the push button switch seen from a direction different from FIG. 1, and FIG. FIG. 4 is a perspective view of a movable mold of a mold used for insert molding of the push button switch as seen obliquely from below, FIG. 4 is a perspective view of a fixed mold of the mold seen from obliquely above, and FIG. 5 is a constituent member of the push button switch. FIG. 6 is a perspective view of a main part of the round wire rod, FIG. 6 is an explanatory view showing a state in which the mold clamping is completed in the insert molding step of the push button switch, and FIG. FIG. 8 is an explanatory view showing a state, and FIG. 8 is an explanatory view showing a state where the mold is opened in the molding step.

The push-button switch shown in FIGS. 1 and 2 has an insulating case 1 made of synthetic resin and formed in a substantially cylindrical shape having a bottom, and a pair of fixed contacts 2 and 2 exposed on the inner bottom surface 1a of the insulating case 1. A terminal 3 which is led out from each fixed contact 2 and projects to the outside of the insulating case 1, and a movable contact 4 which can be contacted and separated from both fixed contacts 2 and 2 by a reversing spring incorporated in the bottom of the insulating case 1. And the insulating case 1 mounted on the movable contact 4
Stem 5 made of synthetic resin that can move up and down along the inner wall surface 1b
And the cover 6 made of a metal plate fixed to the upper end surface 1c of the insulating case 1, the base materials of the fixed contact 2 and the terminal 3 which are in conductive relation are subjected to uneven thickness processing at predetermined positions. One round wire rod 7, a total of two round wire rods 7, 7
Is used by being partially embedded in the insulating case 1. That is, two round wire rods 7, 7 extending in parallel with each other are formed with raised portions 7a, 7a raised upward by uneven thickness processing, and these round wire rods 7, 7 are formed into a cavity of a mold. By forming the insulating case 1 by inserting it into the inside, the raised portions 7a exposed on the inner bottom surface 1a are not used as the fixed contacts 2 and the round wire rods 7 protruding outward from the insulating case 1 are used as the terminals 3. ing. In addition, since the bottom of each raised portion 7a is embedded in the insulating case 1 by this insert molding, these round wire members 7, 7 are hard to rotate with respect to the insulating case 1 and are hard to come off.

Incidentally, bosses 1d are preliminarily provided at a plurality of locations on the upper end surface 1c of the insulating case 1 (see FIGS. 6 to 8).
The cover 6 is attached to the insulating case 1 by caulking each boss 1d, and the stem 5 is prevented from falling off. Further, in this embodiment, as the round wire 7, a wire having good conductivity whose surface is coated with silver is used.

In the push button switch thus constructed, when the operator pushes the stem 5 downward, the movable contact 4 facing the inner bottom surface 1a of the insulating case 1 receives the push driving force and is inverted. Since the fixed contacts 2 and 2 (protuberances 7a and 7a) come into contact with each other, both fixed contacts 2 and 2 are conducted through the movable contact 4 and switched to the switch-on state. When the pushing operation force on the stem 5 is removed in the switch-on state, the inversion of the movable contact 4 returns to the original dome shape by its elasticity, so that the two fixed contacts 2 and 2 are released from conduction and switched off. The state is switched, and the stem 5 receives the elastic force of the movable contact 4 and is pushed up to the initial position shown in FIGS.

Next, a method of manufacturing the push button switch will be described.

The insulating case 1 of this push button switch is shown in FIG.
The mold is formed by combining the movable mold 8 shown in FIG. 4 and the fixed mold 9 shown in FIG. 4, and the round wire 7 is inserted into the cavity 10 of the mold to form the slide cam 11 at the center of the fixed mold 9. Movable pin 12 that can move up and down according to the movement of
When the movable die 8 and the fixed die 9 are clamped, the round wire 7 is unevenly processed into a shape as shown in FIG.

That is, first, as shown in FIG. 6, by inserting the round wire rod 7 into the cavity 10 into which the movable pin 12 has been inserted and clamping the die, the top surface 12a of the movable pin 12 of the round wire rod 7 is closed. And the recess 8a of the movable die 8 is unevenly thickened to bulge upward,
And eggplant It should be noted that the top surface 12a of the movable pin 12 is provided with two recesses 12b having an inner bottom surface curved in an arch shape at two positions facing each round wire 7, and thus is formed by the uneven thickness processing. At the bottom of the raised portion 7a of the round wire rod 7, a groove 12b is formed.
A leg piece 7b corresponding to the shape of is projected.

Next, as shown in FIG. 7, the slide cam 1
1 is moved in the direction of the arrow A to move the movable pin 12 out of the cavity 10, and then the molten resin 13 is filled in the cavity 10 to cool and solidify, so that the round wire 7 is raised on the inner bottom surface 1a. The insulating case 1 with the portion 7a exposed is obtained.

Thereafter, as shown in FIG. 8, the mold is opened and the hoop-shaped round wire 7 is fed by a predetermined amount, whereby the insulating case 1 is transferred to the outside of the mold, and the slide cam 11 is moved.
Since the unprocessed round wire rod 7 is arranged between the movable pin 12 and the movable die 8 that move up in accordance with the movement in the direction of arrow B,
By repeating the above work, insert molding can be continuously performed. Note that reference numeral 14 in FIG. 4 is a known eject pin used when the mold is opened.

When the insulating case 1 is transferred to the predetermined position in this way, the movable contact 4, the stem 5 and the cover 6 are assembled in this order, and each boss 1d of the insulating case 1 is caulked.
Further, the round wire 7 protruding outward of the insulating case 1 is cut or bent to form the terminal 3, and the push button switch as shown in FIGS. 1 and 2 is completed. Then, if the completed push button switch is tape-wrapped with a carrier tape, and is chucked by an automatic mounting machine at the time of mounting and separated from the carrier tape, automatic mounting at a predetermined position on a printed circuit board can be easily performed.

As described above, in the above-described embodiment, the round wire 7 is unevenly formed to form the raised portion 7a, and the bottom portion of the raised portion 7a is embedded in the insulating case 1 including the leg pieces 7b. Insulation case 1 for round wire 7
The anti-rotation strength and the slip-out prevention strength have been remarkably increased, and therefore high reliability is ensured despite the use of inexpensive round wire rods. Further, since the round wire can be cut with a relatively small shearing force, there is an advantage that the blade for cutting the terminal (lead cutter or cutting / clinching blade) is suppressed from being worn and its life is extended. Therefore, the push button switch can significantly reduce the manufacturing cost and does not impair the reliability as compared with the conventional product in which the band-shaped metal plate is processed to form the fixed contacts and the terminals. Then, when the mold is clamped in the insert molding process, the round wire 7 is unevenly thickened in the cavity 10 to increase the protrusion 7a.
Since it is formed, the number of steps can be reduced as compared with the prior art in which a strip-shaped metal plate has been processed into a fixed contact shape as a pre-process, and thus the mass productivity is increased and the raised portion in the cavity 10 is increased. Since the position accuracy of the fixed contact 2 is improved because there is no possibility that the 7a will be displaced, the gap between the fixed contacts 2 and 2 can be set narrower, and the miniaturization of the push button switch can be promoted. The raised portion 7
Since a is formed by eccentricizing the round wire rod 7 in a direction substantially perpendicular to the inner bottom surface 1a, there is no fear that the fixed contact points 2, 2 adjacent to each other will vary in spacing due to the eccentricity of the raised portion 7a. .

FIGS. 9 to 12 are perspective views of the main parts of the round wire rods of the push button switches according to the second, third, fourth and fifth embodiments of the present invention. The shape of 7a and its surroundings is different from that of the first embodiment.

[0024]

As described above, the push-button switch according to the present invention is insert-molded such that the bottom of the raised portion formed by unevenly forming the round wire rod is embedded in the insulating case, and the round wire rod Of these, the portion protruding outward of the insulating case serves as a terminal, and the raised portion serves as a fixed contact, so that the rotation preventing strength and the retaining strength of the round wire material with respect to the insulating case are sufficiently high. It has an excellent effect that reliability is not impaired even if a large cost reduction is made by using a round wire material that is low in material cost and easy to process.
By performing uneven thickness machining of the round wire material in the cavity during mold clamping in the insert molding process, it is possible to prevent displacement of the raised portion in the cavity and improve the positional accuracy of the fixed contact, which reduces the size of the push button switch. In addition to being promoted, it has an excellent effect that the number of steps can be reduced and mass productivity is enhanced.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a push button switch according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of the push button switch seen from a direction different from that in FIG.

FIG. 3 is a perspective view of a movable mold of a mold used at the time of insert molding of the push button switch as seen from diagonally below.

FIG. 4 is a perspective view of a fixed mold of the mold as seen obliquely from above.

FIG. 5 is a perspective view of a main part of a round wire rod which is a constituent member of the push button switch.

FIG. 6 is an explanatory view showing a state in which the mold clamping is completed in the insert molding process of the push button switch.

FIG. 7 is an explanatory diagram showing a state in which a molten resin is filled in the cavity in the molding step.

FIG. 8 is an explanatory diagram showing a state where the mold is opened in the molding step.

FIG. 9 is a perspective view of a main portion of a round wire rod of a push button switch according to a second embodiment of the present invention.

FIG. 10 is a perspective view of a main part of a round wire rod of a push button switch according to a third embodiment of the present invention.

FIG. 11 is a perspective view of a main part of a round wire rod of a push button switch according to a fourth embodiment of the present invention.

FIG. 12 is a perspective view of a main part of a round wire rod of a push button switch according to a fifth embodiment of the present invention.

[Explanation of symbols]

 1 Insulation case 1a Inner bottom surface 2 Fixed contact 3 Terminal 4 Moving contact 7 Round wire 7a Raised part 8 Moving type 9 Fixed type 10 Cavity 12 Moving pin 13 Molten resin

Claims (2)

[Claims] 1. An insulating case made of a synthetic resin material, and a fixed contact formed by exposing a part of a metal member inserted into a cavity of a mold during molding of the insulating case to an inner bottom surface of the insulating case. In a push button switch including a terminal formed by protruding a part of the metal member to the outside of the insulating case, and a movable contact that is incorporated in the insulating case and can be brought into contact with and separated from the fixed contact, the metal member is used as the metal member. Using a round wire material having a raised portion exposed to the inner bottom surface by performing uneven thickness processing, the raised portion of the round wire material serves as the fixed contact, and the bottom portion of the raised portion is embedded in the insulating case. Push button switch characterized in that. 2. A movable pin is inserted into the cavity of a mold, and a round wire rod is inserted into the cavity to clamp the die, whereby the movable pin of the round wire rod and a cavity wall surface facing the movable pin are attached. The sandwiched portion is made uneven to form a raised portion, then the movable pin is withdrawn from the inside of the cavity, and then the inside of the cavity is filled with a molten resin to be cooled and solidified to form an insulating case,
A method for manufacturing a push button switch, wherein the raised portion is exposed on the inner bottom surface of the insulating case.