JPH0763990B2 - Injection mold - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is, for example, a switch case in which terminals for contacts are exposed on the inner bottom surface of a case made of synthetic resin. The present invention relates to an injection molding die for molding a wiring board, which is integrally molded in a state where the terminals are exposed.

[Conventional technology]

As an example of an electric component provided with this kind of wiring board,
The slide type switch is shown in the figure.

In the figure, 1 is a synthetic resin case whose upper surface is an open surface, and 2 is a metal terminal partially embedded in the case 1 when the case 1 is formed. A plurality of pairs of the terminals 2 are installed in a direction orthogonal to the paper surface, and the exposed portion of each terminal 2 in the case 1 serves as the fixed contact portion 2a. 3 is a slider made of synthetic resin, 4 is a slider made of metal, and this slider 4 is attached to the bottom of the slider 3 and is in elastic contact with the fixed contact portion 2a. It should be noted that a plurality of sliders 3 are installed in a direction orthogonal to the plane of the drawing corresponding to the pair of terminals 2. Reference numeral 5 is a cover made of synthetic resin for covering the open surface of the case 1, and a plurality of parallel guide grooves 5a are bored in the cover 5, and the knobs 3a of the slider 3 are respectively provided from the guide grooves 5a. Is protruding. Therefore, when the desired knob 3a is slid along the guide groove 5a, the slider 4 attached to the slider 3 slides on the corresponding fixed contact portion 2a to switch between on and off. Be seen. The cover 5 may be attached to the case 1 by ultrasonic welding or the like.
Is stuck to.

In the slide type switch configured as described above, the case 1 and the terminals 2 are usually integrally formed by using an injection molding die, and the mass productivity is improved.

That is, first, a hoop-shaped metal plate prepared in advance is sequentially fed, and as shown in FIG. 4, a pair of upper and lower frame portions 8 having a large number of feed holes 7 and a plurality of projecting from the frame portion 8 in parallel with each other. The base plate 6 having a predetermined shape, which is roughly configured by the terminal portion 9 and the bridge portion 10 that connects the frame portions 8 facing each other, is pressed. Then, after the base plate 6 is fed into the mold apparatus, a molten resin is injected and injected into the cavity 11 shown by the chain double-dashed line in FIG. next,
This molten resin is cooled and solidified in an injection molding die to mold a synthetic resin case 1 having a plurality of pairs of terminal portions 9 as shown in FIG. After that, each terminal portion 9 is separated from the frame portion 8 at the position shown by the broken line in FIG.
By bending the separated terminal portion 9,
A wiring board (switch case), which is an integrated product of the case 1 and the terminal 2 shown in FIG. 3, is obtained.

By the way, in the injection molding die described above, conventionally, a die structure as shown in FIG. 6 is adopted in the vicinity of the fixed contact portion 2a corresponding to the free end portion of the terminal portion 9. In the figure, 12 is an upper die having a gate 12a, 13 is a lower die having a protrusion 13a, 14
Is a holding pin provided on the upper die 12 in a pair, and 15 is a resin,
After transferring the base plate 6 to the mold device so that the protrusion 13a of the lower mold 13 is located between the pair of terminal portions 9 (between the fixed contact portions 2a), the upper mold 12 and the lower mold 13 are molded. Tighten and inject molten resin 15 into the cavity 11 from the gate 12a.
Here, the free terminal (fixed contact portion 2a) of each terminal portion 9 is adapted to be pressed into contact with the receiving surface B of the lower die 13 by the pressing pin 14 when the die is clamped. There is almost no possibility that the resin 15 will enter between the fixed contact portion 2a and the receiving surface B,
The fixed contact portions 2a can be exposed on the inner bottom surface of the case 1 formed by cooling and solidifying the resin 15.

[Problems to be solved by the invention]

However, the conventional injection molding die described above has a gap between the flat surface of the tip of the presser pin 14 and the receiving surface B due to a slight dimensional error of the die parts and a variation in the thickness dimension of each terminal portion 9. The fixed contact portion 2a that should be sandwiched may not be reliably sandwiched, and in that case, a so-called movement occurs in which the fixed contact portion 2a is shaken on the receiving surface B due to the injection pressure of the resin 15, There is a concern that the fixed contact portion 2a may be displaced after the resin is cooled. For this reason, conventionally, not only high dimensional accuracy is required for mold parts, but also the length of each pressing pin 14 may have to be adjusted at the time of mold clamping, resulting in cost increase.

The present invention has been made in view of the above points, and an object thereof is to provide an injection molding die for molding a wiring board, which can surely clamp the free end portion of the terminal in the cavity and can reduce the cost. To provide.

[Means for solving problems]

In order to achieve the above object, the present invention comprises an upper die and a lower die that sandwich a terminal pressed into a predetermined shape, and a cavity receiving surface defined between the upper die and the lower die. A wiring board in which a molten resin is filled in the cavity with the free end portion of the terminal being in contact with the terminal, and then the molten resin is cooled and solidified to integrally mold the resin molded body with the terminal. In an injection molding die for molding, a conical pressing pin having a pointed tip is fixed to the side facing the receiving surface of the cavity, and the conical tip of the pressing pin is set to the free end of the terminal. The mold is clamped in the state of biting.

[Action]

That is, according to the present invention, the conical tip end of the presser pin bites into the free terminal of the terminal when the mold is clamped. Therefore, even if there is a dimensional error in the mold parts or there is a variation in the thickness dimension of each terminal, the conical tip end There is no risk that the clamping force will undesirably weaken because the biting amount of the part is slightly different, so the molten resin is injected and injected while the free end of the terminal is securely crimped to the receiving surface of the cavity. Therefore, it is possible to reliably prevent the free end from reaching due to the injection pressure.

〔Example〕

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

FIG. 1 is a sectional view showing a mold open state of an injection molding die according to an embodiment of the present invention, and FIG. 2 is a sectional view showing a main part of the injection molding die in a clamped state. The same parts as those in the conventional configuration shown in the figure are designated by the same reference numerals.

As shown in FIG. 1, a fixed block 12b is press-fitted and fixed to the upper mold 12, and a plurality of holding pins 20 each having a quadrangular pyramid tip portion are formed at predetermined positions on the lower end of the fixed block 12b. The book is attached. That is, the upper die 12 is provided with a plurality of presser pins 20 each having a conical tip portion 20a at a position facing the receiving surface B of the cavity 11, and these presser pins 20 are provided.
Are arranged in pairs in a direction orthogonal to the plane of the drawing, in correspondence with the pair of terminal portions 9 of the base plate 6.

In the mold open state shown in FIG. 1, after the base plate 6 with the terminal portion 9 pressed into a predetermined shape is conveyed along the guide portion 13b of the lower mold 13, the mold is clamped as shown in FIG. ,
The base end side of the terminal portion 9 is sandwiched between the upper die 12 and the lower die 13, and the free end portion (fixed contact portion 2a) of the terminal portion 9 is a holding pin.
It is sandwiched between 20 and the receiving surface B. At this time, presser pin 20
Since it is designed in advance so that the distance between the tip of the pin and the receiving surface B is smaller than the plate thickness of the terminal part 9, the conical tip part 20a of the presser pin 20 bites into the fixed contact part 2a, so that it is fixed. The contact portion 2a is strongly pressed against the receiving surface B. After the mold is clamped in this way, when the molten resin 15 is injected and injected into the cavity 11 from the gate 12a, the fixed contact portion 2a is made of the resin 15
However, since the fixed contact portion 2a is strongly pressed against the receiving surface B due to the biting of the presser pin 20, there is no fear that a squeeze will occur, and the fixed contact portion 2a and the receiving surface B are not in contact with each other.
There is no risk that the resin 15 will enter between and. After the resin 11 is thus filled in the cavity 11, the resin is cooled and solidified to open the mold, and the terminal portion 9 is separated and bent to form a wiring board (switch case) in which the resin molded body and the terminal are integrated. ) Is obtained.

As described above, in the above-described embodiment, the pressing pin is used when the mold is clamped.
The conical tip portion 20a of 20 is used as a free terminal (fixed contact portion 2
Since it is bitten into and clamped in a), even if there is a dimensional error in the mold parts or there is a variation in the thickness dimension of each terminal part 9, only the biting amount of the conical tip part 20a is slightly different, and it is clamped. There is no danger of undesirably weakening the force. Therefore, it is possible to inject and inject the molten resin in a state where the fixed contact portion 2a is securely crimped to the receiving surface B of the cavity 11, and it is possible to prevent the fixed contact portion 2a from being affected by the injection pressure and to prevent misalignment. The danger is eliminated. In addition, since the dimensional error of the mold parts is allowed to some extent, the manufacturing accuracy can be relaxed compared to the conventional product, and the length adjustment of the presser pin 20 is almost unnecessary, so the total cost is greatly reduced. can do.

In the above embodiment, the fixed contact portion 2a is sandwiched between the presser pin 20 and the receiving surface B when the mold is clamped. However, another presser pin having a flat tip surface is provided at a position facing the presser pin 20. The fixed contact portion 2a may be sandwiched between these two types of pressing pins.

Further, it goes without saying that the present invention can be applied to the case of molding a wiring board of electric parts such as a variable resistor and an encoder.

〔The invention's effect〕

As described above, according to the present invention in which the conical tip end portion of the presser pin is bitten into the free end portion of the terminal and clamped when the die is clamped, according to the present invention, there is a dimensional error in the mold component or the thickness dimension of each terminal varies. Even if this happens, there is no risk that the clamping force will be undesirably weakened, so it is possible to inject and inject the molten resin while the free end of the terminal is securely crimped to the receiving surface of the cavity. Positional displacement of the terminals due to pressure can be reliably prevented, manufacturing accuracy of mold parts can be relaxed, and adjustment of the length of the presser pin is almost unnecessary, resulting in remarkable effects such as cost reduction. .

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a mold open state of an injection molding die according to an embodiment of the present invention, FIG. 2 is a cross-sectional view of an essential part showing a mold clamping state of the injection molding die, and FIG. 3 is a slide. Sectional views of the mold switch, FIGS. 4 and 5 are explanatory views showing a manufacturing process of this slide type switch, and FIG. 6 is a main part showing a mold clamping state of a conventional injection molding mold used in this manufacturing process. FIG. 1 ... Case, 2 ... Terminal, 2a ... Fixed contact part, 6 ...
Base plate, 9 ... Terminal, 11 ... Cavity, 12 ... Upper mold, 13 ... Lower mold, 15 ... Resin, 20 ... Presser pin, 20a ...
… Conical tip, B… Receiving surface.

Claims (1)

[Claims] 1. A free end portion of a terminal is provided on a receiving surface of a cavity defined between the upper die and the lower die, the upper die and the lower die holding a terminal pressed into a predetermined shape. Injection mold for wiring board molding, in which molten resin is filled in the cavity in a state of being in contact with the resin and then the molten resin is cooled and solidified to integrally mold the resin molded body with the terminals. In, on the side facing the receiving surface of the cavity,
An injection molding die characterized in that a conical pressing pin having a pointed tip is fixed, and the conical tip part of the pressing pin is clamped in a state of biting into the free end part of the terminal. Type.