JPS5947037A - Manufacture of dial of wristwatch and the like - Google Patents

Abstract

PURPOSE:To form as one body a dial which scarcely has residual stress and has reliability in its strength, by executing superplastic working until a fixed strain or a fixed load is obtained, and thereafter, executing a creep deformation in a state that a fixed load is loaded to a base material. CONSTITUTION:A metal A showing superplasticity at a specified temperature is placed on a die 1, and a punch 2 is rolling-reduced at a constant speed in a specified temperature zone. When superplastic working advances, an incomplete projecting part is formed in recessed parts 1a, 2a of the dies on the upper and lower faces of the base material A, and also internal stress is generated in the base material A, therefore, when it reaches some step, the punch 2 is stopped in a state that a fixed load is loaded. By this operation, a virtual strain speed of the base material A drops, therefore, during this time, the base material A goes into a minute part of the first and second recessed parts 1a, 2a, while causing a creep deformation, and forming is completed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a dial of a portable watch using a metal that exhibits superplasticity in a specific temperature range.

The dial of a portable watch usually has two or more legs planted on the back of the dial in order to position and fix it to the movement, and high-quality dials do not have The time mark, maker's mark, etc. are formed on the surface of the implant. Therefore, the more difficult machining steps required to manufacture conventional dials, the more difficult it is to avoid problems such as thermal deformation of the dial when brazing the foot cap. He was an old man.

To solve this problem, the technology proposed in Japanese Patent Application Laid-Open No. 50-55521 uses a metal that exhibits superplasticity in a specific temperature range to create characters such as time indicators, manufacturer marks, and supporting feet. An attempt was made to reduce costs by integrally molding the entire plate, but when considering the allowable plate thickness for a dial of a portable watch, the molding load would be excessive, and, for example, In areas where a thin dial requires a large amount of deformation, such as corners and protruding parts perpendicular to the dial, breakage may occur due to excessive stretching of the material, or insufficient forming due to a decrease in plastic flow. Unfilled areas called ghosts are likely to occur on the surface of the dial where the
There is a problem in that it is impossible to mold a high-grade dial using the above-mentioned techniques.

In view of such problems, the present invention performs superplastic processing at a size that reaches a certain strain or a certain load necessary for forming, and then applies a certain load to the material to maintain the material for creep deformation. By reducing the apparent strain rate of the material, it is possible to create time markers and supports that are one to several times the thickness of the dial on both sides of the dial in a detailed manner. The purpose of the present invention is to provide a new method for manufacturing a dial that can be formed into

Therefore, the details of the present invention will be explained below based on examples.

Fig. 1 shows an example of the manufacturing process for the dial of a portable watch based on the method of the invention. is dial 3
A recess 1a corresponding to the supporting foot 5d to be formed is formed on the back side of the first mold 2.
In this case, there is a shape rJ on the surface of the dial 3, as shown in Fig. 3.
! A time indicator 33s, a maker mark 3b, and a calendar display window frame are provided.

In this way, the basic composition is -1 type IK, a metal that exhibits superplasticity at a specific 7kN degree, for example, a Zn-41 co-reciprocal alloy containing 20 to 24% A and l in terms of weight t1 ratio, O~4.0 weight of Ou and O~1-07r1: [f
ZnZn-Al with microcrystalline powder structure added with i% Ml
-0u-alloy up to 1 in the temperature range of 200-600℃
A disk-shaped metal material A that has been heat-treated to bring about plastic deformation of 5oO or more is placed in the library, and then molded through molds 1 and 2. , for example, to 200 to 000°C 7, and under these four conditions, the upper die 2 is rolled down on the stacked material A at a constant speed.

By the way, the deformability of metals that exhibit superplasticity depends on the strain rate (1).On the other hand, when the same forming is applied to a material using compressive force, the rate of deformation of the material after forming or the material The smaller the thickness of the plate, the thicker it is.

In other words, the smaller the plate thickness on the bare side, the more the strain will increase during ultra-9+Jj processing, and if the stiffness becomes large, it will lead to material breakage, so at a certain stage of forming. The period during which the sweetness of tansuru is reached, the period during which the strain or load necessary for Rumatanohi reaches a certain level, the upper mold 2
The pressure is reduced at a slow speed of, for example, about 5 steps/minute.

As this superplastic working progresses, the upper and lower surfaces Vc of the material are formed with incomplete protrusions in the recesses 1a and 2a of the dies 1 and 2, as shown in FIG. A large internal stress is generated in the material A along with i'1, so when these reach a certain stage, the 11 upper mold 2 loaded with a constant load is stopped! make it work.

Due to this operation, the apparent strain rate of material A decreases, and during this time, material A causes a creep hairstyle and enters into the minute parts of the recesses 1a and 2a of mold 1.2. Molding is completed.

〔Example〕

22 Al for weight, 0.5 CI+ for weight, 0.0
N key 0.53 mm based on Zn-22φA4 co-phase fine grain superplastic alloy containing 5-layer viscous M, 9,
A thin disk-shaped material with a diameter of 0 mm is placed on the surface with a height of 0.
．． 30mmO time indicator, Geneva pattern, upper die engraved with maker mark, diameter is Q, 65mm, depth is 1.6
Place it between the lower mold, which has a 5 mm recess for forming a foothold.
t'c L,,, with the above material heated to 260''C, while applying a maximum load of 61cg / rrnl, 5
．． o mrrh Plastic working at an initial forming speed of 7 minutes,
After that, when the material was subjected to creep deformation by applying the above load for 300 seconds, it was actually observed that the time indicators and supporting legs grew on the upper and lower surfaces of the material at the speed shown in Fig. Forming was completed at a time index Fi of 150 to 240 seconds with a low sieve, but the long legs, which were six times the thickness of the material, continued to grow at a constant speed, and Kt l-'
i: The required length was reached after so many seconds. moreover,
When this method was compared with the conventional implantation method,
There is no significant difference in appearance between the finished products, and the manufacturing cost is 1.
It has become clear that it can be reduced by 1/12.

As described above, according to the present invention, a superplastic metal sheet material is subjected to superplastic processing until forming reaches a certain stage, and then a certain load is applied to this thin sheet material to cause creep deformation. Therefore, it can be used inside the rib plate by superplastic processing; l/(
- By reducing the stress that occurs over time through creep processing, it is possible to create a dial plate with low residual stress and high strength in LIk shape. death,
However, by applying the creep force () that follows the superplasticity 11 and 2V, it is possible to create a state in which the strain rate is lowered by 4 and 1, so that the superplasticity is The elongation of the plate material can be perfectly copied to the thin plate 4A with the size of the uneven part of 11. IJ] It becomes oil to easily and inexpensively print a high-class mobile phone (i) / 06 meter dial.
Then 3': can be done.

4. Drawing h1j Simple guess, Figure 1 (a), (b) i, Based on the method of the present invention.
Figure 2 shows the progress of molding in the creep process when 1-1°<1
Figures (a) and (b) are a top view and a plan view of the yen letter plate formed by the upper process of [I31].

1...1 type, 2...Upper type, 3...Auxiliary score board, A...
Super-uniform metal base plate material.

Fig. 1
J

Claims (1)

[Claims] 1. A superplastic metal sheet material is molded using one mold, which is formed by carving a concave part corresponding to a time indicator, etc. that is to be formed protrudingly, and the other mold, which is formed by drilling four parts corresponding to the supporting legs. A constant load is applied to the thin plate material during the process of superplastic working at a strain rate depending on the plate thickness and the period from the time when the forming process reaches a certain stage until the forming process is completed [2. In addition to the deformation process, 1. mobile phone Jt3
A method of manufacturing a clock dial.