JPS62107042A - Outer ornament parts for watch - Google Patents

Abstract

PURPOSE:To improve corrosion resistance as well as creep resistance by incorporating prescribed percentage of copper, titanium, magnesium and zinc. CONSTITUTION:The titled outer ornament parts for watches are composed of an alloy consisting of, by weight, 0.15-2% copper, 0.03-0.4% titanium, 0.01-0.03% magnesium and the balance zinc. Above-mentioned outer ornament parts have superior creep resistance, so that inferior waterproofing as well as dimensional change with the lapse of time is minimized and resultingly corrosion resistance can be improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is aimed at improving the exterior parts of mobile watches, which were conventionally made of zinc die-casting, which is good at mass production, due to the diversification of consumption and the reduction in the number of products and products. The present invention relates to exterior parts for portable watches using forging zinc alloy, which can be produced more cheaply than die-casting in high-variety, low-volume production, and has good quality, as the per-manufacturing cost is increasing.

[Summary of the invention]

The present invention aims to improve the creep resistance and mechanical performance of the material by adding Cu, Ti, and Mg to Zn in a well-balanced manner.It has good workability, is easy to manufacture, and has excellent surface treatment properties such as plating. To obtain exterior parts for mobile watches with excellent corrosion resistance.

[Prior Art and Problems to be Solved by the Invention] Currently, the cheapest metal exterior parts for portable watches are manufactured by zinc die casting.

Zinc alloy for die casting is Aj! by weight! 3.9-4.
It is an alloy consisting of 3% Mg, 0.03 to 0.06%, and the remainder substantially zinc. Zinc die-cast exterior parts for mobile watches have the following characteristics. To enumerate, the advantages are: - Good reproducibility of shape.

■Suitable for high-volume production of small quantities and low cost.

■Proven track record in machinability and surface treatment.

In addition, the following points can be mentioned as drawbacks.

■Die-casting mold cost is expensive. (Disadvantageous for high-mix, low-volume production) ■Creep (elongation) under stress of 5Kgf/mm2,
It is about 0.2 to 0.3% after 1000 hours at room temperature, which is not very good.

■Casting defects such as cavities, pinholes, and hot water wrinkles are unavoidable, leading to lower yields and deteriorating the corrosion resistance of plating.

Applying zinc die-casting, which has both advantages and disadvantages as described above, to exterior parts for portable watches, which are produced in a wide variety of products and in small quantities, would lead to increased costs and unstable quality. The exterior component for a portable watch using the forging zinc alloy of the present invention completely changes this situation and provides an exterior component for a portable watch that is inexpensive and has stable quality and yield.

[Means for solving problems]

In zinc alloys for die casting, the addition of Al is essential to improve strength, but it reacts with Ti added to improve creep resistance in molten zinc, resulting in A1. It forms Ti and prevents the formation of TiZn1B, which is effective for creep resistance. Furthermore, since AI is a component that impairs surface treatment properties,
It is not a desirable element for a creep-resistant alloy for forging. That is, in the present invention, weight 1"i' 0.15 to 2.0
% (7) copper, 0.03-0.40% titanium, 0.
A highly creep-resistant zinc alloy for forging is used, which is characterized by containing 0.01% or more and less than 0.03% magnesium, and the remainder being zinc containing unavoidable impurities.

The present invention is aimed at forging processing, and focuses on creep resistance, surface treatment properties, cutting properties, and polishing properties, and uses a small amount of Cu,
It is an alloy containing Ti and Mg, and is characterized by not containing AI. Furthermore, Cu, which is an effective additive component,
Another feature is that Ti and Mg have little effect of canceling out or interfering with each other's effects.

■ Effect of copper (Cu) Cu has the effect of increasing the recrystallization temperature and increasing the stability of the alloy at room temperature. Up to 1.0%, Zn forms a solid solution in Zn and has the effect of increasing strength within the range of working from the cast state to 70%, but when it exceeds 2.0%, the degree of work softening increases and Zn The dimensional change increases with the precipitation of the ε phase, which is an intermetallic compound. Also, Cu has a small amount of Ti.
If it exceeds 2.0%, the formation of TiZn+5 is hindered and the creep resistance is lowered. If it is less than 0.15%, the recrystallization temperature decreases and physical properties tend to change over time.

Based on the above, the content was determined to be in the range of 0.15 to 2.0%.

(2) Effects of titanium (Ti) In addition to increasing hardness, Ti forms TiZn+5 at grain boundaries due to heat generated during annealing or rolling and prevents grain boundary sliding due to external forces, thereby improving creep resistance.

If it is less than 0.03%, the effect of increasing creep resistance will be weak, and if it is more than 0.4%, the alloy will become brittle and workability will decrease. Based on the above, the range was determined to be 0.03-0.40%, but
In order for the alloy for die casting (ZDC-2) to have excellent creep resistance, a content of 0.15% or more is required, and from the viewpoint of forging workability, a content of 0.30% or more is desirable. In addition to this, Ti has the effect of making crystals finer during solidification from molten metal, and contributes to stabilizing the quality of the ingot.

■Effect of Magnesium (Mg) Mg has the effect of significantly increasing the hardness of zinc alloys. 0
．． The effect begins to appear at 0.01% and reaches a saturated state at 0.03%, and compared to Zn-Cu-Ti alloys that do not contain Mg, the Pinkers hardness improves by IIV 10 or more and HV
It will be 75-80. As far as hardness is concerned, o and oos% are effective, but if the addition amount is less than 0.01%, the elongation of the material after annealing decreases to 10% or less.

In the case of zinc alloys, if the elongation at room temperature does not reach 5%, the material will hardly elongate at temperatures below 0°C, making it unsuitable for practical use. Therefore, a necessary condition is that the elongation at room temperature be 10% or more. Mg is a small amount in Zn, but Ti
If the content exceeds 0.03%, this tendency increases and not only interferes with the effect of increasing the creep resistance of Ti, but also interferes with the crystal refining effect peculiar to Ti. From the following, the practical range is 0.01% or more and less than 0.03%, but preferably 0.01 to 0.05%.

〔Example〕

The present invention greatly improves creep resistance by adding copper, titanium, and magnesium to zinc in a well-balanced manner, making it possible to manufacture low-cost exterior parts for portable watches with corrosion resistance.

Table 1 shows the creep test results of the conventional Zn material for die casting (ZDC-2) and the Zn alloy of the present invention, and Table 2 shows the results of corrosion resistance and plating adhesion when a mobile watch case was made from each material. shows.

Table 1 Creep resistance test results The test samples were processed into a hikoze shape by forging and casting.
A static pressure load of Kgf/++m'' was applied and held at room temperature for 1000 hours, and the elongation of the sample was examined.

Table 2 Corrosion resistance and plating adhesion test results Test samples were made by cutting and polishing a mobile watch case formed by forging or casting.
20μ)+Crp (0.2μ) plating treatment was performed to examine corrosion resistance and adhesion.

Table 1 shows that the conventional Zn alloy for die casting (ZIIC-2) has a concentration of 0.2 to 0.3% for die cast products and 7.5% for forged products.
The Zn alloy of the present invention elongates by ~40.0%, whereas the elongation of the Zn alloy according to the present invention is not measured, and the creep property is clearly improved. This is very advantageous as it removes structural and design constraints when used as a material for the exterior of a portable watch. In addition, as shown in Table 2, conventional Zn alloy for die casting (ZD
C-2) and the processing method (die-casting method) have major problems in both corrosion resistance and plating adhesion, leading to a decrease in yield in terms of manufacturing and becoming a factor in raising costs. On the other hand, the Zn alloy for forging according to the present invention shows excellent results in both corrosion resistance and plating adhesion. Furthermore, the forgeability as a form of workability is extremely excellent, as it can be formed into a desired shape with -1 press work. It also has good machinability and polishability, making it possible to manufacture high-quality, low-cost exterior parts for portable watches.

〔Effect of the invention〕

The creep-resistant zinc alloy exterior parts for mobile watches according to the present invention have good creep resistance, so there is little dimensional change over time (there are fewer waterproofing defects, there are no pinholes, so there is good corrosion resistance, and it is suitable for high-mix, low-volume production. , resulting in an exterior that is inexpensive to manufacture.

that's all

Claims (1)

[Claims] 0.15-2.0% copper by weight, 0.03-0.40%
An exterior part for a portable watch made of a creep-resistant zinc alloy containing titanium of