JPH01171921A - Injection mold - Google Patents

Abstract

PURPOSE:To prevent reliably tottering of a free end due to injection pressure, by a method wherein a press pin whose tip part is drill-like is provided on a side facing on a receiving surface of a cavity and mold clamping is performed under a state where a drill-like tip part is encroached upon a free end part of a terminal. CONSTITUTION:When mold clamping is performed a base end side of a terminal part 9 is held between a top and bottom forcess 12, 13 and a free end part (a stationary contact point part 2a) of the terminal part 9 is held between a press pin 20 and receiving surface B. In this instance, a drill-like tip part 20a of the press pin 20 is encroached upon the stationary contact point part 2, therefore, the stationary contact point part 2a is welded strongly to the receiving surface B with pressure. Although the stationary contact point part 2a is exposed under injection pressure of molten state resin 15 when the resin 5 is injected/cast into a cavity 11 through a gate 12a after the mold clamping like this, as the stationary contact point part 2a is pressed strongly against the receiving surface B through encroaching by the press pin 20, there is neither a fear of generating tottering nor a fear that the resin 15 enters between the stationary contact point part 2a and receiving surface B.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable to a switch case in which a contact terminal is exposed on the inner bottom surface of a synthetic resin case. This invention relates to an injection molding die for molding a wiring board that is integrally molded with terminals exposed.

[Conventional technology]

As an example of an electrical component equipped with this type of wiring board, the third
The figure shows a slide type switch.

In the figure, 1 is a synthetic resin case with an open top surface, and 2 is a metal terminal that was partially buried during the molding of this case L, and the left and right sides shown face each other with a predetermined gap A. A plurality of pairs of terminals 2 are installed in a direction perpendicular to the plane of the paper, and the portion of each terminal 2 exposed inside the case 1 serves as a fixed contact portion 2a. 3 is a synthetic resin slider, 4 is a metal slider, and this slider 4
is attached to the bottom of the slider 3 and the fixed contact part 2
It is in elastic contact with a. Note that a plurality of sliders 3 are installed in a direction perpendicular to the plane of the paper in correspondence with the pair of terminals 2. Reference numeral 5 denotes a cover made of synthetic resin that covers the open surface of the case 1. A plurality of parallel guide grooves 5a are bored in the cover 5, and each guide groove 5a leads to a knob 3a of the slider 3. stands out. Therefore, when a 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 perform on/off switching. Note that the cover 5 is fixed to the case 1 by ultrasonic welding or the like.

In the slide type switch configured in this way, the case 1 and each terminal 2 are usually integrally molded using an injection mold, and mass productivity is improved.

That is, first, hoop-shaped metal plates prepared in advance are sequentially fed, and as shown in FIG. A base plate 6 having a predetermined shape, which is roughly constituted by terminal portions 9 and bridging portions 10 connecting opposing frame portions 8, is press-worked. After this base plate 6 is sent into a mold apparatus, molten resin is injected into a cavity 11 shown by a two-dot chain line in FIG. Next, this molten resin is cooled and solidified in an injection mold to form a case 1 made of synthetic resin and provided with a plurality of pairs of terminal portions 9, as shown in FIG. Thereafter, each terminal part 9 is separated from the frame part 8 at the position indicated by the broken line in FIG. 5, and by bending the separated terminal part 9, the case 1 and the terminal 2 are integrated as shown in FIG. A wiring board (switch case) is obtained.

By the way, the injection mold described above has conventionally adopted a mold structure as shown in FIG. 6 in the vicinity of the fixed contact portion 2a corresponding to the free end portion of the terminal portion 9. In the same figure, 1
Reference numeral 2 is an upper mold having a gate 12a, 13 is a lower mold having a protrusion 13a, 14 is a presser pin provided in a pair on the upper mold 12, and 15 is a resin between the pair of terminal parts 9 (refixing). After transporting the base plate 6 to the molding device so that the protrusion 13a of the lower mold 13 is located between the contact portions 2a), the upper mold 12 and the lower mold 1
3 is clamped, and molten resin 15 is injected into the cavity 11 from the gate 12a.

Here, the free terminal (fixed contact portion 2a) of each terminal portion 9 is as follows:
Since the presser pin 14 presses against the receiving surface B of the lower mold 13 during mold clamping, the molten resin 15
There is almost no spread between the fixed contact portion 2a and the receiving surface B, and the case 1 is made by cooling and solidifying the resin 15.
Each fixed contact portion 2a can be exposed on the inner bottom surface of the.

[Problem that the invention seeks to solve]

However, in the conventional injection mold described above, due to slight dimensional errors in the mold parts and variations in the thickness of each terminal part 9, there is a gap between the flat surface of the tip of the presser pin 14 and the receiving surface B. The fixed contact part 2a that should be held may not be held securely, and in that case, the injection pressure of the resin BFi 15 may cause the fixed contact part 2a to wobble on the receiving surface B, causing the resin to cool. There is a concern that the fixed contact portion 2a may become misaligned later. For this reason, in the past, not only high dimensional accuracy was required for mold parts, but also the length of each presser pin 14 had to be adjusted during mold clamping, resulting in an increase in costs.

The present invention has been made in view of the above-mentioned points, and its purpose is to provide an injection mold for molding wiring boards, which can securely hold the free end of a terminal within the cavity, and can reduce costs. It is about providing.

[Means for solving problems]

In order to achieve the above object, the present invention includes an upper mold and a lower mold that sandwich a terminal pressed into a predetermined shape, and a receiving surface of a cavity defined between the upper mold and the lower mold. A wiring board in which the cavity is filled with molten resin with the free end of the terminal in contact with the terminal, and then the molten resin is cooled and solidified to form a resin molded body integrally with the terminal. In an injection mold for molding, a presser pin having a conical tip is provided on the side facing the receiving surface of the cavity, and the conical tip of the presser pin is bitten into the free end of the terminal. The mold was configured to be clamped in this state.

[Effect]

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

〔Example〕

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

FIG. 1 is a cross-sectional view showing an injection molding die according to an embodiment of the present invention in an open state, and FIG. 2 is a cross-sectional view of essential parts showing the injection mold in a closed state. Portions equivalent to those in the conventional configuration shown in the figure are given the same reference numerals.

As shown in FIG. 1, the upper mold 12 has a fixed block 12b.
is press-fitted into the fixing block 12b, and a plurality of presser pins 20 each having a square pyramid-shaped tip are attached to a predetermined position on the lower end of the fixing block 12b. That is, the upper mold 12 is provided with a plurality of holding pins 20 each having a conical tip 20a at a position facing the receiving surface B of the cavity 11, and these holding pins 20 hold the pair of base plates 6. Eggplant terminal part 9
A plurality of sets of two wires are arranged in a direction perpendicular to the paper surface, corresponding to each other.

In the mold open state shown in FIG.
When the mold is clamped as shown in FIG. Part 2a)
is held between the presser pin 20 and the receiving surface B. At this time, since the distance between the tip of the presser pin 20 and the receiving surface B is designed in advance to be smaller than the thickness of the terminal portion 9, the conical tip portion 20a of the presser pin 20 is attached to the fixed contact portion 2a. Therefore, the fixed 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 into the cavity 11 from the gate 12a, the fixed contact part 2a is exposed to the injection pressure of the resin 15, but the fixed contact part 2a is bitten by the presser pin 20. ,
Since 2a is strongly pressed against the receiving surface B, there is no widening that would cause sagging, and there is no collapse that would cause the resin 15 to enter between the fixed contact portion 2a and the receiving surface B. Thus the cavity
After filling the inside with resin 15, it is cooled and solidified, the mold is opened, and the terminal portion 9 is separated and bent to obtain a wiring board (switch case) in which the resin molded body and the terminal are integrated. It will be done.

In this way, with the above implementation side number, the conical tip 20a of the presser pin 20 bites into the free terminal (fixed contact part 2a) of the terminal part 9 and is held therein, so that the mold part can be dimensioned. Even if there is an error or a variation in the thickness dimension of each terminal portion 9, the amount of biting of the conical tip portion 20a is only slightly increased, and there is no widening that would undesirably weaken the clamping force. Therefore, the molten resin can be injected while the fixed contact part 2a is securely pressed against the receiving surface B of the cavity 11, and the fixed contact part 2a can be prevented from shifting due to injection pressure, thereby reducing the risk of misalignment. has been removed. Also,
Since dimensional errors in the mold parts are allowed to a certain extent, the manufacturing precision can be relaxed compared to conventional products, and there is almost no need to adjust the length of the presser pin 20, so the total cost can be significantly reduced. Can be done.

In addition, in the above embodiment, when the mold is clamped, the presser pin 20 and the receiving surface B
However, another presser pin with a flat tip is provided at a position facing the presser pin 20, and the fixed contact portion 2a is held between these two types of presser pins. It may be configured.

It goes without saying that the present invention is also applicable to molding wiring boards for electrical components such as variable resistors and encoders.

〔Effect of the invention〕

As explained above, according to the present invention in which the conical tip of the presser pin bites into the free end of the terminal and clamps it during mold clamping, there may be dimensional errors in the mold parts or variations in the thickness of each terminal. Even if there is, there is no widening that would undesirably weaken the clamping force, so the free end of the terminal is placed on the receiving surface 6ζ of the cavity.
The molten resin can be injected while the resin is securely crimped, and as a result, it is possible to reliably prevent the terminal from shifting due to injection pressure, and it is also possible to reduce the manufacturing precision of the mold parts, reducing the length of the presser bin. Since there is almost no need to adjust the height, significant effects such as cost reduction can be achieved.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing an injection molding die according to an embodiment of the present invention in an open state, Fig. 2 is a sectional view of essential parts showing the injection mold in a closed state, and Fig. 3 is a slide A cross-sectional view of the mold switch, FIGS. 4 and 5 are explanatory diagrams showing the manufacturing process of this slide type switch, and FIG. 6 is a main part showing the mold closing state of the conventional injection mold used in this manufacturing process. FIG. 1... Case, 2... Terminal, 2a...
... Fixed contact part, 6 ... Base plate, 9 ...
...Terminal section, 11...Cavity, 12.
...Top mold, 13...Bottom mold, 15...
...Resin, 20...Press pin, 20a...
...Conical tip, B...Receiving surface. Figure 1 13 ・ Figure 2 Figure 3

Claims (1)

[Claims] It comprises an upper mold and a lower mold that sandwich a terminal pressed into a predetermined shape, and the free end of the terminal is brought into contact with a receiving surface of a cavity defined between the upper mold and the lower mold. In an injection mold for molding a wiring board, the cavity is filled with a molten resin, and then the molten resin is cooled and solidified to form a resin molded body integrally with the terminal. A presser pin having a conical tip is provided on the side facing the receiving surface, and the mold is clamped with the conical tip of the presser pin biting into the free end of the terminal. injection mold.