JPH09145855A - Wristwatch exterior member and working method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable molding into a complicated form with high strength and reduction of working time by cold-working a specified weight of specified material and titanium alloy, and thermostatic forging using the worked blank. SOLUTION: Cold rolling with the draft of 10, 20, 40, 60% is applied to a titanium alloy containing 4.0-5.0% aluminium, 2.5-3.5% vanadium, 1.5-2.5% molybdenum and 1.5-2.5% iron by weight, the residue being titanium and an obligatory component to obtain a sample A. A forging blank is picked from the sample A and a BN; lubricant is applied. After application, the blank is set with a metal mold in a thermostatic forging machine heated to 750 deg.C to perform thermostatic forging to a watch exterior part. Thus, a complicated form with high strength can be obtained and the working time can be shortened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of processing a titanium alloy wristwatch exterior product manufactured by a constant temperature forging method.

[0002]

2. Description of the Related Art Conventionally, cold forging, hot forging, or isothermal forging has been performed for forming a material for a wristwatch exterior part using a titanium material such as pure titanium for commercial use or a titanium alloy. . As shown in the machining process diagram of FIG. 4, the forging material used for those forging is used to remove the machining strain generated by the cold rolling after finally performing the thickness dimensioning by the cold rolling. A plate material having an equiaxial structure state as shown in the photograph in FIG. 4 which has been subjected to softening annealing for the purpose of recrystallization is used. This plate material was punched into a ring shape or a can-attached shape to form a blank for forging exterior parts of a wristwatch.

Commercially pure titanium, which has a relatively low strength, can be molded into a relatively complicated shape during cold forging or hot forging, but titanium alloy has a high strength and can be molded into a complicated shape. Since it is difficult, isothermal forging has conventionally been used to form a complex-shaped part.

[0004]

However, if the conventional titanium alloy having an equiaxed structure in which recrystallization is completed by annealing is isothermally forged, the forging time becomes long. Further, since the forging load is increased, the mold may be deformed, and it takes time to maintain the mold, resulting in an increase in the manufacturing cost of the wristwatch exterior part.

Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art, to form a high-strength and complex shape, and to reduce the processing time and processing cost. To get the way.

[0006]

Means for Solving the Problems In order to solve the above problems, the present invention relates to aluminum of 4.0 to 5.0% by weight, 2.
5-3.5% vanadium, 1.5-2.5% molybdenum, 1.5%
~ 2.5% of iron, the balance is titanium and titanium alloy which is an unavoidable component cold working, blank after the cold working,
Alternatively, a blank annealed at a temperature that does not recrystallize after cold working was used for isothermal forging.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. (1) First Example The test material used in the present invention is a β-rich (α + β) type Ti-4.5Al-3V-2Mo-2Fe alloy having the chemical composition shown in Table 1. The tissue is an equiaxed tissue having an average particle size of about 2 μm.

[0008]

[Table 1] This sample material has a rolling reduction of 10% as shown in FIG.
20%, 40% and 60% cold rolled sample A
Was prepared. A forging blank as shown in FIG. 3 was taken from this sample A. After applying the BN lubricant to this blank, both molds were set in a constant temperature forging machine heated to 750 ° C., and after holding for about 4 minutes, the forging speed was 0.06, 0.1.
Stroke rate at 5, 0.6 and 1.5 mm / min 4.
Constant temperature forging was performed up to 5 mm. Here, the final shape of the forged product is the wristwatch case shown in FIG. After constant temperature forging,
The maximum forging load and die filling state were investigated. Table 2 shows the results.

[0009]

[Table 2] At a forging speed of 0.15 mm / min or more, a blank that has been cold-rolled at any forging speed is a blank annealed at 800 ° C at which recrystallization ends (comparative material in Table 2). ), The forging load is smaller, and the mold filling property is improved. In addition, these characteristics become more remarkable as the rolling reduction increases.

(2) Second Example The same test material as in the first example was subjected to cold rolling with a reduction rate of 10%, 20%, 40% and 60% as shown in FIG. Annealing was performed at 720 ° C. where recrystallization was not completed, and FIG.
A sample B having a processed structure as shown in the photograph was prepared.
This sample B to the same forging blank as in the first embodiment.
Was collected. This blank was subjected to isothermal forging under the same forging conditions as in the first example. Here, the final shape of the forged product is also the same as in the first embodiment shown in FIG. After the isothermal forging was completed, the maximum forging load and the die filling state were examined. Table 3 shows the results.

[0011]

[Table 3] When annealed at 720 ° C after cold rolling,
At a rolling reduction of 20% or more and a forging speed of 0.15 mm / min or more, recrystallization does not end after cold rolling at any forging speed. A blank annealed at 720 ° C anneals at 800 ° C at which recrystallization ends. The forging load is smaller than that of the blank (comparative material in Table 2), and the mold filling property is improved. In addition, these characteristics become more remarkable as the rolling reduction increases.

It is needless to say that the same effect can be obtained in this embodiment as long as the annealing temperature after cold rolling is in a temperature range where recrystallization is not completed, particularly at a temperature of 720 ° C. or lower.

[0013]

As described above, the present invention is by weight.
4.0-5.0% aluminum, 2.5-3.5% vanadium,
A titanium alloy containing 1.5 to 2.5% molybdenum and 1.5 to 2.5% iron with the balance titanium and an unavoidable component was used to obtain a titanium alloy with good cold workability. Blank after cold working,
Alternatively, a blank having a textured structure that was annealed at a temperature at which recrystallization was not performed after cold working was used, and isothermal forging was performed on a wristwatch exterior part. Since it is recrystallized during isothermal forging, processing strains are also removed, and due to the refinement of crystal grains during isothermal forging, the forging time can be significantly shortened and the forging load can be reduced.

[Brief description of the drawings]

FIG. 1 is a process drawing of a titanium alloy used for a forging blank of the present invention.

FIG. 2 is a drawing-substituting photograph of the structure of the titanium alloy used in the forging blank of the present invention.

FIG. 3 is a sectional view of a forging blank of the present invention.

FIG. 4 is a sectional view of a forged product of the present invention.

FIG. 5 is a process diagram of a titanium alloy used for a conventional forging blank.

FIG. 6 is a drawing-substituting photograph of the structure of a titanium alloy used in a conventional forging blank.

Claims (2)

[Claims] 1. Aluminium, 4.0-5.0% by weight, 2.5-
3.5% vanadium, 1.5-2.5% molybdenum, 1.5% -2.
A constant temperature is obtained by cold working a titanium alloy containing 5% iron and the balance titanium and unavoidable components, and using a blank after the cold working or a blank that has been sintered at a temperature that does not recrystallize after the cold working. Exterior parts for wristwatches characterized by forging. 2. Aluminum of 4.0-5.0% by weight, 2.5-
3.5% vanadium, 1.5-2.5% molybdenum, 1.5% -2.
5% iron is added, the balance is titanium and titanium alloy which is an unavoidable component is cold-worked, the blank after the cold-working, or a blank that has been annealed at a temperature that does not recrystallize after cold-working, A method of processing a watch exterior part, which is characterized by constant temperature forging.