JPS604014A - Manufacture of wrist watch case - Google Patents

Abstract

PURPOSE:To obtain a gold-plated case excellent in quality by less processes by a method wherein the middle with back of a watch case is electroformed by a combination of nickel, copper or alloy gold, and the middle with back is inserted into an injection mold for injection molding. CONSTITUTION:A plastic electroformed matrix 4 transferred from a surface- finished electroforming master model is processed by injection molding, compression molding, etc. A conductive cover 5 is provided by vacuum deposition, electroless plating, etc. Then, a metal such as nickel, copper, gold or silver is electrodeposited by electroforming. In manufacturing an electroformed middle with back 1, an electroformed piece is used as a secondary electroforming master 7 to conduct a thick plating 7a and to apply releasing lubricant 7b then to be mounted on a glass plate 8. Then, the gap between a glass ring 9 and the glass plate 8 is sealed by clay 10 and heat resistant resin is poured inside the glass ring 9, hardened and finished. The finished piece is incorporated into an injection cavity 12 and an insert mold to complete a mold.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is characterized in that the outer surface of the body of the wristwatch, especially the outer surface of the body, is made of gold.
The present invention relates to a method of manufacturing a shell case made of plastic.

Conventional shelled cases have been manufactured by drawing or brazing a metal shell, but with this method, the dimensions of the shell and injection cavity can be precisely matched during insert injection molding. However, since the shape of the shell is partially deformed by the molding pressure during insert molding, surface finishing such as abrasive grinding must be performed in a subsequent process, which has the following disadvantages.

(1) The heat generated by the abrasive grinding process in the post-process creates a minute gap between the shell and the plastic, which deteriorates the adhesion between the shell and the plastic inner shell.

(2) In the case of a shell that requires a plating finish such as gold plating, the plating solution enters the gap created in (1) and cannot be completely removed afterwards, resulting in very poor corrosion resistance.

The present invention was made in order to eliminate the above-mentioned drawbacks, and to reduce the number of steps, reduce the cost of injection cavity molds, provide a high-quality gold-plated case, and at the same time obtain a good finished appearance. This is the manufacturing method.

The present invention will be explained in detail below with reference to embodiments shown in the drawings.

Figure 1 shows a watch side manufactured by the method of the present invention. 1 is an electroformed watch side that has the appearance specifications required for a watch side on the surface and has a complicated and high quality pattern by electroforming. It is a shell, and the inside is made up of a plastic inner shell 2.

In order to manufacture the above-mentioned watch side, first, as shown in Fig. 2, a plastic electroforming master mold 4, which is faithfully transferred from an electroforming master whose surface has been finished with the desired design, is molded using a known plastic molding method, for example. Processed by injection molding, compression molding, etc. Next, a conductive coating 5 is formed on the surface of the plastic electroforming mold 4 by vacuum evaporation or electroless plating to give conductivity, and then a plateable metal such as nickel, copper, gold, or silver is applied. The electroformed shell 1 is formed by electrodeposition by electroforming. Next, when manufacturing the injection cavity 12 of the insert mold, the mask 6 is
The second electroformed master 7 was electroformed without setting, and a thick plating 7α was applied to the surface of the secondary electroformed master.
After applying the lIi formulation 7b, it is placed on a glass plate 8. Next, after sealing the gap between the glass ring 9 and the glass plate 8 with adhesive i10, heat-resistant resin or metal powder-containing heat-resistant resin 1
1 is poured and hardened, and the post-processed material is incorporated into an insert molding mold to form an injection cavity 12 to complete the mold. The thick plating on the secondary master 7 is to provide a clearance between the electroformed shell 1 and the injection cavity 12, and the amount of clearance varies depending on the shape of the watch side, but is preferably about 5μ to 1000μ. Furthermore, the heat-resistant resin that is the material of the injection cavity 12 has greater strength when it contains metal powder, and is stronger when it contains about 80% by weight of metal powder. The metal powder preferably contains metal powders such as aluminum, iron, copper, nickel powder, stainless steel, etc., and inorganic powders such as aluminium, mina, etc. Next, the electroformed shell 1 is subjected to post-processing such as the glass insertion part and the buttonhole part by cutting, press punching, etc., and then coated with a finishing plating layer made of precious metals such as nickel, gold, rhodium, and chromium, and then molded into an insert molding mold. The watch side is completed by injection molding.

In the method of the present invention, the injection cavity of the insert molding mold is made of heat-resistant resin or heat-resistant resin containing metal powder based on the electroformed shell as described above, so that there is no space between the electroformed shell and the injection cavity. Since there is no gap, there is no deformation of the shell due to the pressure during injection molding, and there is no need for finishing processing after injection molding, so finish plating can be done before insert injection molding.
It becomes possible to manufacture shelled cases with a gold-plated finish.

In addition, since the external shape can be expressed freely, designs can be diversified, and watch sides with complex and high-quality patterns that are extremely difficult to mass-produce using normal machining methods can be mass-produced. Furthermore, since the surface pattern is accurately reproduced from a high-quality finished master, there is no need for finishing such as abrasive cloth in the final process, which has great effects such as improved processing efficiency.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of the watch side manufactured by the method of the present invention, Fig. 2 is a cross-sectional view of the electroformed shell manufactured in the manufacturing process of the present invention, and Fig. 3 is a cross-sectional view of the manufacturing process of the indisc 6 facility of the present invention. FIG. 4 is a cross-sectional view of the mold during insert molding. 1... Electroformed shell 2°°°°° Plastic inner shell 3... Glass 4... Glass electroformed mother mold 5...
Conductive film 6...Mask 7...Secondary electroforming master 7α...Thick plating layer 7b...Release material coating layer 8...Glass plate 9... ...Glass ring 10 ... Viscosity 11 ... Heat-resistant resin or heat-resistant resin containing metal powder 1
2... Inji Exi Expansion Cavity 13...
...Insert molds and above Applicant Daini Seikosha Co., Ltd.

Claims (2)

[Claims] (1) In the method for manufacturing the body of a wristwatch, the shell of the body constituting the outer surface of the body is produced by electroforming of one or a combination of two or more of nickel, copper, or a metal alloy, and then injection molded. Method of inserting the protruding body shell into the mold. (2) The method for manufacturing a wristwatch according to claim 1, wherein a part or all of the cavity shape of the injection mold is made of a heat-resistant resin or a heat-resistant resin containing metal powder.