JPS60154013A - Manufacture of rubber mold - Google Patents

Abstract

PURPOSE:To make easier the manufacture of a rubber mold as well as to raise the smoothness and accuracy of parting line by a method in which a lower rubber mold is formed, a releasing agent layer of a powder and a membrane is provided on the parting line of the lower rubber mold, and a rubber not hardened by reaction is cast onto the parting line of the lower rubber mold and hardened to form an upper rubber mold. CONSTITUTION:A wooden mold 2 coated with a releasing agent is placed on a base 1 coated with a releasing agent, and a casting frame 3 is set around them. A fluid silicon rubber not hardened by reaction is cast into the frame 3 to cover the wooden mold 2 ahd hardened by reaction to form a lower mold 4. The parting line 6 of the lower mold 4 is turned upwards, graphite is rubbed into the parting line 6 and the exposed surface of the mold 2 by means of cotton, etc., and the excess portion of the graphite is removed. PVA dissolved in a solvent (e.g., water, alcohols, etc.) is coated on the graphite of the parting line 6 and dried to form a releasing agent layer 5. A casting frame 7 is set on the lower mold 4, the rubber not hardened by reaction is cast into the frame 7 and hardened to form an upper mold 8. The releasing agent layer 5 adhered to the parting lines 6 and 9 is removed.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a method for manufacturing a rubber mold used for molding synthetic resin or the like.

BACKGROUND TECHNOLOGY Conventionally, for example, when manufacturing a rubber mold to be used in a prototype, a wooden mold or the like of the same shape as the synthetic resin molded product to be prototyped was created, and then it was encapsulated in silicone rubber, and then reaction-cured silicone rubber was coated with it. It was not a scale that was very difficult to mold with a knife, etc., and it also had drawbacks in terms of quality, such as the cross section of the cut being rough.

Purpose This invention has been made to solve the above-mentioned conventional problems, and it not only simplifies manufacturing by eliminating the need for cutting the mold (the upper mold and the lower mold can be separated). It is an object of the present invention to provide a novel method for manufacturing a rubber mold, which is free from the risk of adhesion during manufacturing and can also form a smooth and highly accurate parting surface.

EXAMPLE Hereinafter, an example in which this invention is embodied in a prototype rubber mold G will be described with reference to the drawings. Reference numeral 1 represents a horizontal platform. 2
is a wooden mold placed on table 1, and is formed to have the same shape as the synthetic resin molded product to be prototyped. 3 is a casting flask installed on the stand 1 so as to surround the wooden mold 2. Reference numeral 4 denotes a lower mold made of silicone rubber, which is formed by pouring unreacted silicone rubber into the flask 3 so as to surround the main mold 2 and then hardening it. Reference numeral 5 denotes a mold release agent layer formed on the parting surface 6 of the lower mold 4 after the formation of the lower mold 4, and includes powdered graphite rubbed on the parting surface 6 and PvA coated on the graphite. (Polyvinyl alcohol, manufactured by Dainippon Ink Co., Ltd., product number R330 was used.) A part of the graphite is pushed into the surface of the parting surface 6, making the parting surface 6 a rough surface. There is.

7, after the lower die is installed so that the parting surface 6 is above,
This is a flask for an upper mold installed on the flask 3. Reference numeral 8 denotes an upper mold made of silicone rubber, which is formed by pouring silicone rubber before reaction and hardening onto the lower mold 4 having a mold release agent layer 5 and then hardening it.

After forming the upper mold 8, the release agent layer 5 is removed from the parting surface 6 of the lower mold and the parting surface 9 of the upper mold.

The procedure for manufacturing the prototype rubber mold configured as described above will be explained with reference to the drawings.

First, as shown in FIG. 1, a wooden mold 2, also coated with a mold release agent, is placed on a table 1 whose surface is coated with a mold release agent such as PVA, and a mold 3 is installed around it.

Next, the silicone rubber in a fluid state before the curing reaction is poured into the mold 3 and the wooden mold 2 is wrapped around it, and then the silicone rubber is reacted and hardened to form the lower mold 4.

Next, as shown in Fig. 2, align the cutting surface 6 of the lower mold 4 upward, and press graphite into the exposed surface of the wooden mold 2 and the cutting surface 6 using cotton, etc. , make the parting surface 6 a rough surface. Graphite that adheres excessively and does not bite into the parting surface 6G is removed. Next, PV'A dissolved in a solvent such as water or alcohol is applied to the graphite on the parting surface 6. PvA is coated on silicone rubber and dried to form a film to form a mold release agent layer 5.Generally, PvA is repelled on silicone rubber and is difficult to wet, but in this example, the parting surface 6 is roughened with graphite. Therefore, the wettability of PVA is improved and it is possible to apply a thin layer to the entire parting surface 6.

Next, after setting the casting flask 7 on the lower mold 4,
After pouring the silicone rubber before reaction and hardening into the mold, the silicone rubber is hardened to form the upper mold 8. Thereafter, the mold release agent layer 5 adhering to the parting surfaces 6 and 9 may be removed.

As described above, in this embodiment, the upper mold 8 and the lower mold 4 are already formed separately at the time of manufacturing the prototype rubber mold, so the upper mold and the lower mold are cut into the upper mold and the lower mold after manufacturing the rubber mold as in the conventional method. There is no need to do this, and it is easy to manufacture.
9 can be formed smoothly and accurately.

Furthermore, although silicone rubber has a property of being highly adhesive, in this embodiment, the parting surface 6 of the lower mold 4 is coated with a mold release agent layer 5 at the same time as the upper mold 8 is formed. The silicone rubber of the upper mold 8 before reaction hardening does not come into direct contact with the lower mold 4. Therefore, both molds 4.8 do not adhere to each other and can be easily separated.

It should be noted that the present invention is not limited to the configuration of the embodiment described above, but can also be embodied in the following manner.

(1) In this example, graphite and PVA solution are used in the mold release agent layer 5, but instead of graphite, activated carbon, talc (Mg(o)
n) In 2), various powders such as AI powder may be used, or various materials that form a membrane such as vinyl acetate solution may be used instead of PvA.

(2) The upper mold 8 and the lower mold 4 are made of rubber other than silicone rubber. In particular, rubbers with excellent heat resistance such as acrylic rubber and fluororubber are suitable.

(3) Furthermore, the rubber mold of the present invention can be used not only as a mold for various prototypes, but also as a female mold for electroforming molds, a female mold for resin molds, and a mold for final products that require only a small number of moldings.

Effects As described in detail above, in this invention, after forming the lower mold 4 from rubber, a mold release agent layer 5 made of powder and a film is provided on the parting surface 6 of the lower mold 4, and then, before reaction curing, By pouring the rubber into the parting surface 6 of the lower mold 4 and curing the same rubber to form the upper mold 8, there is no need to cut the mold, making manufacturing easier. This has the excellent effect that there is no risk of the mold adhering during manufacturing (and the parting surface can be formed with smoothness and high precision).

[Brief explanation of drawings]

1 to 3 show an embodiment embodying the present invention. FIG. 1 is a sectional view when forming a lower mold, FIG. 2 is a perspective view of the lower mold, and FIG. 3 is a cross-sectional view of the lower mold. is a sectional view of the lower mold and the upper mold. Wooden mold 2, lower mold 4, mold release agent layer 5, parting surface (of the lower mold) 6, upper mold 8゜ Patent applicant Konan Tokushu Sangyo Co., Ltd. Agent Patent attorney Hironobu Onda Figure 1 Figure 2

Claims (1)

[Claims] 1. After forming a lower mold (4) from rubber, a mold release agent layer (5) made of powder and a film is provided on the parting surface (6) of the lower mold (4), and then Rubber before reaction hardening is placed on the parting surface (6) of the lower mold (4).
), and the rubber is cured to form an upper mold (8). 2. The mold release agent layer (5) is formed on the parting surface (6) of the lower mold (4). A method of manufacturing a rubber mold according to claim 1, characterized in that the method comprises: providing a rubber mold;