JPH0636820U - Push Button Switch Cover Mold for Molding - Google Patents

Abstract

(57) [Summary] (Correction) [Construction] Pushbutton switch A pushbutton in which the surface of the die 2 on the contact point formation side of the cover member is rougher than the surface of the die 1 on the keytop formation side. Mold for molding switch cover members. [Effect] When the deformed push button switch cover member made of an elastic rubber material opens the mold, all of them are in close contact with the mold for forming the contact portion and can be easily and safely removed from the mold efficiently. Since a high yield is achieved, excellent productivity can be obtained over a long period of time, and it has a much higher industrial value than conventional dies.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold for molding, and more particularly to a mold for molding a push button switch cover member having improved moldability.

[0002]

[Prior art]

 Usually, the push button switch cover member is composed of a key top part for touching a finger and a base part for holding the key top part, and the key top part has a strength and hardness suitable for transmission by pressing the finger. For example, the contact portion is formed in the shape of a prism, a pyramid, a cylinder, a cone, or the like, and a contact portion is formed on the lower surface of the key top portion so as to project slightly downward, and the key top portion is The peripheral portion of the lower surface is joined and held integrally with the base portion. The columnar keytop body is usually a block-shaped member having a height of about 2 to 8 mm, more often about 3 to 7 mm, and a diameter or one side of about 5 to 20 mm. For example, a contact portion having a diameter of 2 to 4 mm smaller than the bottom surface and a downward protruding height of 0.5 to 0.9 mm is integrally formed in the central portion.

A molding die for manufacturing such a push button switch cover member uses two split molds having surfaces respectively corresponding to the shapes of the upper surface side and the lower surface side of the cover member. Then, the material is press-fitted into the cavity. A deep recess corresponding to the key top is formed in the upper mold on the key top forming side, and a shallow recess corresponding to the convex shape of the contact is formed on the lower mold on the contact forming side combined with this. A cavity is formed between both molds so that a relatively thin base member is integrally joined to the peripheral edge of the lower end surface of the key top.

Conventionally, such a push button switch cover member is made of silicone rubber, natural rubber, unvulcanized rubber material such as EPDM or NBR on the lower die of the contact portion forming side and the key top portion forming side. It is manufactured by injection molding or transfer molding in the cavity of the split mold formed with the upper mold. However, in molding with such a split mold, due to the peculiar shape of the cover member as described above, when the split mold is opened, the molded product always adheres to the mold on the front surface of the key top, There is a drawback in that it is troublesome to separate this from the mold and requires manpower, and in some cases, the mold is not well separated, so that pulling with strength causes damage to the weak dome and the like.

As a method of eliminating or reducing such a mold release defect from the mold on the key top side forming side, conventionally, for example, a surfactant-based, silicone-based or fluorine-based release agent is used. A method of applying only or a large amount of the die for forming the key top portion, a die in which a fluorine-based resin layer having good releasability is applied and formed on the surface of the die for forming the key top portion, and a die for forming the contact portion Method of combining dies whose surface is chrome-plated or nickel-plated, or the side surface of the contact-forming projection of the cover member for pushbutton switch is in the range of 50 to 80 ° with respect to the bottom surface of the contact portion. A method was used that used a lower mold with a recess that was inclined at an internal angle to form a downwardly open ridge.

However, in the case of the above method, since the mold release agent adheres to the molded product, it must be removed, and, for example, an extra operation such as washing was necessary. In addition, the method (1) has a drawback that the fluorine-based resin formed by coating on the surface of the key top portion on the molding side is an extremely soft material and is worn out in a relatively short period of time, so that it has to be coated again. Further, in the case of the above method, there is a problem that the mold release of the die for forming the key top portion is insufficient, the molded product is easily broken when the die is opened, and the yield is lowered.

[0007]

[Problems to be solved by the device]

 Therefore, it is an object of the present invention to provide a push button switch cover member molding technique in which the mold release property of the molded product from the mold on the key top portion forming side is excellent. Another object is to provide a mold for manufacturing a push button switch cover member which is industrially advantageous in terms of high productivity and yield.

[0008]

Means for Solving the Problems That is, according to the present invention, in a cover member molding die for a push button switch, the surface of the die on the contact member forming side of the cover member is formed on the key top portion forming side. We propose a combination of dies for forming pushbutton switch cover members that are formed to be rougher than the surface of the die. Especially, when the die is opened after molding, the formed elastic molding material is the key top part. There is a technical feature in forming the mold surface on the contact part forming side to an appropriate roughness so that it does not adhere to the mold on the forming side and remains on the surface of the mold on the contact part forming side.

As the material for forming the cover member of the push button switch molded by the mold of the present invention, the elastic rubber materials as described above are preferably used. For example, a representative material is silicone rubber. Those having excellent weather resistance are particularly preferably used. An appropriate amount of a commonly known vulcanization catalyst and various other additives are compounded in these materials.

The pushbutton switch cover member having a peculiar shape according to the present invention is formed by a split mold having a corresponding cavity. The surface roughness of the lower mold on the contact portion forming side is formed by the key top portion. It is important that the side surface of the mold is sufficiently rougher than the surface of the mold. The surface roughness of both molds is, for example, the surface area of the unit area of the mold on the key top forming side of the engraved part of the maximum key of the molded product and the same surface area of the mold on the contact forming side. In contrast, the surface roughness of these molds is usually empirically or through a few simple experiments to facilitate the relative roughness of the molds, depending on the desired state of mold release from the upper mold of the molded article. You can decide.

The formation of such a rough surface is finished by using sand, river sand, cast iron grit, steel grit, cut wire, alumina grit, silicon carbide grit, slag grit, etc. as a blasting material. The method of spraying the surface of the mold to make it rough is advantageously adopted. Those grain shapes are sieved into various grain size ranges, and the blasting material and grain shape are selected and used according to the desired rough surface formation. For spraying, conventionally known devices such as a centrifugal blast device, a suction blast device or a pressure blast device can be conveniently used.

Table 1 below shows the ratio of the surface of the engraved portion of the die on the side forming the key top portion to the die on the side forming the contact portion and the size of the blast material in the maximum key of the molded product.

TABLE 1 Maximum key - size of the mold surface area ratio blasting material wood - top side (X) contacts the side key - top part side contact portion X <1 1 ♯ 100 ♯ 100 1 <X <50 1 ♯ 100 # 80 50 ≤ X <65 1 # 100 # 60 65 ≤ X <80 1 # 100 # 40 80 ≤ X 1 Must be used in combination with a conventionally known method.

The mold of the present invention is used by combining the molds having different actual surface areas of the inner surface as described above, and the elastic material is injection-molded or transfer-molded in the cavities of the upper and lower molds that are joined together. The push button switch cover member is manufactured with good releasability. The difference in the surface roughness of such a mold can be easily determined empirically depending on the material or by simple experimentation.

Next, the mold of the present invention will be described in more detail with reference to the accompanying drawings. FIG. 1 is a schematic partial sectional view of a cavity portion of an example of the mold of the present invention. In the figure, the surface of the die 1 on the key top portion forming side of the push button switch cover member is formed to be rougher than the surface of the die 2 on the contact portion forming side, and a void formed by both surfaces. 3 constitutes a cavity corresponding to the cover member for the push button switch. There is a recess 4 for forming a key top on the surface of the die 1 on the side where the key top is formed, and a recess for forming a contact is provided on the surface of the die 2 on the side where the contact is formed. 5 are provided. Further, the lower peripheral edge of the key top portion is integrally joined with the push button switch base 6 and the dome portion 7.

[0015]

[Action]

 The mold of the present invention is industrially extremely advantageous because the cover member for a push button switch made of an elastic molding material is molded with good mold release, resulting in excellent manufacturing efficiency and a higher yield.

[0016]

【Example】

Example 1 and Comparative Examples 1 and 2 A cover member for a push button switch was molded using a mold as shown in FIG. Both the surface of the mold for forming the key top portion of the cover member and the surface of the mold for forming the contact portion were plated with chrome, and both surfaces were blasted. Blasting is performed with a suction blasting device on a die with a key top part forming side mold engraving surface area of 1,597 cm ² and a contact part forming side mold engraving surface area of 25 cm ² at the maximum key. Using cast iron grit as a blast material, # 100 was used for forming the key top portion, and # 60 was used for forming the contact portion, and injection molding was performed using a roughened combination die.

For comparison, both surfaces of the key top portion forming side and the contact portion forming side are plated with chrome by the above-described conventional method, and a release agent / Die-free (manufactured by Daikin Industries, Ltd.) is used for the kit. When molding is performed while applying to the mold for forming the cap portion (Comparative Example 1), and for the mold for forming the key top portion by the conventional method described above, Kaniflon plating (a fluororesin manufactured by Kanigen Japan Co., Ltd. is used. 1000-shot molding was carried out and the molding conditions were compared between the case where the molding work was carried out with a metal mold which was subjected to system plating and the mold for forming the contact portion was provided with chromium plating (Comparative Example 2).

As a result, in the case of using the mold of the present invention, when the mold is opened, the molded product is always in close contact with the mold on the contact part forming side, and the molded product is on the contact part forming side. It could be easily released from the mold. When the mold was opened, the adhesion rate to the mold on the contact part formation side was 100%. Also, in the conventional method, the molded product adheres to the die on the key top portion side from the first shot, and therefore the adhesion rate to the die on the contact portion forming side is 0%, and it is difficult to release the die. there were. Furthermore, in the conventional method, the molded product adhered to the mold on the contact formation side up to 300 shots, but if it was longer than that, there was a tendency to adhere to the mold on the key top side, and satisfactory results were obtained. I couldn't do it.

[0019]

[Effect of device]

 According to the mold of the present invention, when the deformed push button switch cover member made of the elastic rubber material is brought into close contact with the mold for forming the contact portion when the mold is opened, it can be easily and safely removed from the mold. Because it can be performed well and high yield is achieved, it has excellent productivity over a long period of time, and its industrial value is far higher than that of conventional dies.

[Brief description of drawings]

FIG. 1 is a schematic partial cross-sectional view of a cavity portion of an example of a mold of the present invention.

[Explanation of symbols]

 1 Mold for forming key top part 2 Mold for forming contact part 3 Gap (cavity) 4 Recess for forming key top part 5 Recess for forming contact part 6 Push button switch base 7 Dome part

Claims (1)

[Scope of utility model registration request] 1. A mold for molding a cover member of a push button switch, wherein the surface of the mold on the contact member forming side of the cover member is keyed.
A mold for molding a push button switch cover member, which is formed to be rougher than the surface of the mold on the top portion forming side.