JPS6015696B2 - Manufacturing method for exterior parts for mobile watches - Google Patents

Description

[Detailed description of the invention] The present invention has excellent insect resistance, impact resistance, abrasion resistance, abrasion resistance, and mirror gloss, and can be carried on a daily basis for a long period of time with almost no loss of its initial appearance. , which relates to a new method for manufacturing a gold alloy coated exterior part for a portable watch.

Conventional gold alloy coated exterior parts for mobile watches are mainly wet gold plated on lid copper and nickel silver, and some high-end products include gold plating on austenitic stainless steel or wet gold plating on silver alloy. There are also gold-plated products.

When conventional gold alloy plated products are used for long periods of time, the surface inevitably peels off, the surface layer disappears due to wear, and the corrosion resistance decreases due to this.
Scratches, discoloration, dents caused by strong impact, resulting in peeling of the surface area, and corrosion and elution of the base material occurred, seriously detracting from the appearance of a portable watch.

Furthermore, although gold-plated parts have better carrying quality than plated parts, the deterioration in appearance quality due to long-term carrying is exactly the same as that of plated parts, due to their low hardness. In addition, conventional parts of this type have a hardness of H for both the base material and the surface layer.
It did not exceed v200, and the specular gloss of the surface finish was unsatisfactory as a decorative item.

In order to compensate for the drawbacks of the exterior parts for mobile watches coated with gold alloy, the present invention aims to solve the problem of peeling of the surface layer by improving the adhesion of the surface layer, improve the hardness of the surface layer, and increase the hardness of the base material. The objective is to provide a product that is sufficiently durable for long-term use and has excellent specular gloss unmatched by conventional products by making improvements such as preventing marks and depressions and improving specular gloss. In order to achieve this object, in the present invention, first, an exterior part for a portable watch is manufactured from an age-hardening steel alloy that increases in hardness when exposed to low temperatures.

In this manufacturing process, at least the final surface finishing is performed after the base material is subjected to age hardening treatment. After wet or dry deposition of Au-Ni-Co gold alloy, which also improves hardness using low-temperature arm anchors, on the surface of the exterior parts manufactured in this way, the entire part is subjected to age hardening treatment of the base alloy. Heat treated below temperature. Through these steps, the final polished surface of the base material has an extremely beautiful finish, the adhesion of the surface layer to the base material is greatly improved, and the hardness of the surface layer is increased, at least to the extent that the base material does not become soft. In addition, such heat treatment can reduce defects in the coating process of the surface layer.
For example, pinholes formed by wet plating or dry plating,
It is possible to prevent a decrease in the insect resistance of the substrate due to areas with poor adhesion, and it also has the effect of stabilizing the metallographically unstable areas of the surface layer, thereby improving the corrosion resistance of the surface layer itself. In this way, the present invention achieves high levels of corrosion resistance, abrasion resistance, scratch resistance, surface layer adhesion, and specular gloss, which have been difficult to obtain with conventional gold alloy-coated exterior parts for mobile watches. Even if you can get it and carry it for a long time,
This made it possible to manufacture excellent products with almost no damage to the appearance. The amount of Au in the surface layer is 50% (
When the weight ratio is below 96%, it is difficult to obtain a golden color, and the corrosion resistance is also poor, and when it is above 96%, aging hardness is difficult to obtain.
In addition, when Co is less than 1%, it is difficult to obtain the desired aging hardness, and when Co is more than 25%, the color tone of the surface layer is not good, and
After heat treatment, the surface layer becomes loose and cracks are likely to occur in the surface layer. Also, if Ni is less than 1%, the color tone of the surface layer will not look luxurious, and the adhesion after heat treatment will be good and it will be thick. If it is more than 25%, the color tone of the surface layer will become golden. Moreover, the desired corrosion resistance cannot be obtained after heat treatment.

Co and Ni have the effect of imparting age hardenability to the Au alloy, and the effect is greatest when the ratio is 1:3. In addition, in the case of the surface layer having the composition shown above, the curing treatment temperature range is 1
50 o - 550 o0, but within this range, alloys that can interdiffuse with the surface layer of this composition to improve adhesion, do not reduce the hardness of the surface layer due to diffusion, and do not soften themselves. Age hardenable steel alloys are most suitable.

For example, with alloys other than steel alloys that have a lower softening point than copper alloys, even if the surface layer can be hardened by competing anchors, the base material will inevitably soften;
Co-based alloys require a high interdiffusion temperature in order to increase adhesion, and therefore, even if adhesion is good, desired properties in terms of hardness and color tone of the surface layer cannot be obtained in many cases. Furthermore, depending on the alloy, there is almost no interdiffusion, and areas with poor adhesion often peel off during heat treatment, resulting in poor appearance such as peeling. In addition, for example, in the case of ordinary copper alloys such as yellow steel and nickel silver, it is possible to improve the hardness by lining processing and then heat treatment below the softening point to harden the surface layer and improve adhesion. be. However, the forging process for forming this type of alloy into exterior parts for mobile watches requires several rounds of phosphorous annealing, and the cold working rates for each part are different, so before the final polishing process is reached, It is impossible to maintain a uniformly high hardness in all parts of the part, and therefore it is not possible to obtain a uniform and excellent final surface polished finish. The present invention will be described below with reference to Examples.

Example 1 By cold forging after solution treatment, B with a weight ratio of 1.92%
e. After molding a case for a mobile watch using Mr.-Cu alloy containing 0.31% Co, removing burrs, cutting and polishing, 315q
After performing age hardening treatment for 3 hours, final polishing was performed.

After performing a wet Ni flash of 0.75 μm, gold alloy plating of 83.3% Au, 12.4% Co, and 4.3% Ni was performed, followed by 300 μm in a hydrogen atmosphere.
Diffusion and surface hardening heat treatment were performed for q05 hours. As a result, a completed case having a base hardness of Hv410 and a surface layer hardness of Hv430 was obtained. A case with the same shape as this case is made of nickel silver, and after the usual under plating process, it is 76.4%A.
The mobile quality was compared with a product that was plated with 13.8%Ag, 5.4%Cu, and 4.4%Ni alloy. As a result, the product of the present invention showed 3 times more wear resistance, 8 times more corrosion resistance, 5 times more adhesion strength, and 2 times more impact resistance than conventional products.
Moreover, it was found that the specular luster of ordinary mobile phones is hardly lost. Example 2 In the same process as in Example 1, a weight ratio of 19.3% Ni, 2
A case for a mobile watch is manufactured from an age-hardening steel alloy consisting of 0.5% Mn and the balance Cu, and after final polishing, the
．． 3% A13) Using an alloy consisting of 3% A and Ni as a target, a 4.3% gold alloy layer is formed on the surface by sputtering.
A diffusion hardening treatment was carried out at 420° C. for 2 hours to obtain a product with a base hardness of Hv450 and a surface hardness of Hv480.

The basic quality of this product as a case also showed significantly superior characteristics compared to ordinary 23K gold plated or clad products. Example 3 In the same process as Example 1, the weight ratio was 20.4Ni, 20
．． A glass bezel for a portable watch is manufactured from an aging alloy with a balance of Cu and a wet process of 75.4% Au and 18.4% Au.
Wet plating of a gold alloy consisting of %Co and the balance Ni
Buddhist practice, 400o03 in ammonia decomposition gas atmosphere
Through time diffusion and curing treatment, we succeeded in producing glass chips with excellent properties.

Example 4 A mobile watch band was manufactured using a technical-Cu alloy consisting of 1.84% Be, 0.2% Be, and the balance Cu by weight, and the final surface finish after age hardening treatment was wet-treated. 78.4%A
Wet plating a gold alloy consisting of u, 16.3% Co, and the balance Ni at 300o in an argon gas atmosphere for 4.5 steps.
After 04 hours of diffusion and hardening heat treatment, a golden band exhibiting excellent mobile quality was obtained.

Claims (1)

[Claims] 1 A portion or the entire surface of a part that has been subjected to age hardening treatment using an age hardenable copper alloy, or the entire surface is coated with 50% to 96% Au, 1% to 25% Co, and 1% by weight.
A mobile watch exterior characterized in that after depositing an alloy layer consisting of ~25% Ni and the remainder unavoidable impurities, heat treatment is performed within a range that does not reach the age hardening temperature of the base copper alloy to harden the surface area. How the parts are manufactured.