JP3041585B2 - Mainspring manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power spring for a small precision instrument such as a wristwatch and a method for manufacturing the power spring.

[0002]

2. Description of the Related Art Since a power spring of a wristwatch requires high output torque, durability and corrosion resistance, a Co-based alloy of high elasticity and high corrosion resistance is used as the material.

[0003]

The output torque of the mainspring is expressed by the following equation. T = Ebt ³ πN / 6L T: Output torque E: Young's modulus of material b: Width of mainspring t: Thickness of mainspring N: Effective number of turns of mainspring L: Length of mainspring No increase in thickness and width of mainspring In order to obtain a high output torque, a material having a high Young's modulus may be used, but the Young's modulus of a conventionally used Co-based alloy is 2,000 to 2100.
A power spring material having a Young's modulus higher than 0 kgf / mm ² and excellent in durability and corrosion resistance has been demanded.

[0004]

In order to solve the above-mentioned problems, a mainspring material according to the present invention is made of Co-N having high mechanical strength and Young's modulus, excellent durability and corrosion resistance.
An i-based alloy was used. This Co-Ni-based alloy is, for example,
The composition is 30-40% Co, 27-36% Ni by weight,
Cr 12 to 26%, Mo 8 to 13%, Mn, Ti, A
l, one or more of Fe 0.1 to 3% each, Nb
0.5-3%, misch metal 0.005-0.05
% And a Co-Ni-based alloy consisting of unavoidable impurities.

Here, 30-40% of Co, 27-36% of Ni
The reason for limiting to a Co-Ni-based alloy containing% is that there is no notch brittleness and it is excellent in mechanical strength, fatigue strength, corrosion resistance, and workability. If the Co content is less than 30%, the mechanical strength decreases, and if the Co content exceeds 40%, the alloy becomes hard and the cold workability decreases, which is inappropriate.

The reason why the content of Ni is set to 27 to 36% is to show the optimum range for maintaining the mechanical strength and the workability. Fe
Has the same effect as Ni, but is in this range so as not to lower the corrosion resistance. Cr 12-26%, Mo8-
The reason for 13% is that the optimum range having corrosion resistance is shown under the conditions containing Co and Ni. If it is less than the lower limit, the corrosion resistance is poor. If it exceeds the upper limit, it becomes unsuitable because it becomes hard and difficult to work in cold working. It depends. Mn helps the effect as a deoxidizing agent and softens the matrix during the solution treatment. Al has an effect as a deoxidizing agent and an effect to increase mechanical strength. Ti has an effect of crystal grain refinement. Nb has the effect of further increasing the mechanical strength, but 3%
If it exceeds, it becomes too hard and is unsuitable. Misch metal has the effect of improving hot workability.

[0007] This alloy is melted by vacuum melting, and then forged, hot rolled, hot drawn, solution treated, cold drawn, and annealed.
Cold drawing is performed to a final working ratio of 30 to 90%, which is represented by the area reduction rate. Since this alloy is hard and has high deformation resistance, it is drawn by a reverse tension wire drawing machine using a drawing die. The wire is cold-rolled to a predetermined thickness of a mainspring. Here, the reason why the wire is rolled is that the rolling direction of the material is aligned with the direction in which the Young's modulus of the crystal is high, so that the output torque of the mainspring can be further increased.

The reason why the final degree of drawing is set to 30% or more is that
The rolling direction of the material is aligned with the direction of high Young's modulus of the crystal,
The lower limit value at which the effect of further increasing the output effect of the mainspring appears is shown. The reason why the final drawing degree is set to 90% or less is that if the working degree is higher than this, the toughness of the mainspring becomes weaker even if it is reduced. It is. The rolled material thus finished is cut into a predetermined width, and is subjected to edge polishing, cutting, forming, aging treatment, welding, and Teflon vapor deposition to finish the spring. The aging treatment is performed in a vacuum or a non-oxidizing atmosphere at a temperature of 400 to 620 ° C. for 2 to 3 hours.

FIG. 1 shows an example of the shape of a power spring for a wristwatch.
FIG. 2 shows an example of a manufacturing process of a mainspring.

[0010]

According to the above construction, a spring having a high output torque and excellent in durability and corrosion resistance can be obtained.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Co-Ni base alloy (alloy A) and conventional C
A power spring for wristwatches was processed using an o-base alloy (alloy B) and the characteristics were compared. Table 1 and Table 2 show alloy A, respectively.
And the composition of alloy B. Table 3 shows the Young's modulus of alloy A and alloy B.

[0012]

[Table 1]

[0013]

[Table 2]

[0014]

[Table 3] Hereinafter, the mainspring made of alloy A will be referred to as the mainspring of the present invention, and the mainspring made of alloy B will be referred to as comparative mainspring. Each alloy is melted by vacuum melting and subjected to forging, hot rolling, hot drawing, solution treatment, cold drawing, annealing, and then reverse tension using a carbide drawing die. Final processing degree 60 at normal temperature with wire drawing machine
% Wire drawing was performed to obtain a wire having a wire diameter of 3 mm. The wire is rolled to a thickness of 0.12 mm at room temperature and has a width of 0.95 mm.
Then, edge polishing was performed.

Next, it was cut into a length of 370 mm, formed and processed, and an outer hook was welded to the end of the mainspring. Then 500 ° C
For 2 hours in vacuum, and finally, Teflon was vacuum-deposited on the surface to complete the mainspring. This spring was inserted into a barrel car and the characteristics of the spring were examined. Inside diameter of barrel car is 1
0.60 mm and the core diameter is 2.80 mm.

FIG. 3 shows a state where the mainspring 1 is inserted into the barrel car 3. Reference numeral 2 in the figure is an outer ring of the mainspring, and reference numeral 4
Is the barrel core. Table 4 shows the output torque T _0.5 of each spring.
(Output torque in a state in which the mainspring is fully wound up for about 0.5 hour), output torque T ₂₄ (output torque in a state in which the mainspring is wound up for about 24 hours), and the number of turns N related to the duration. As can be seen from Table 4, the mainspring of the present invention has a T _0.5 of 15% and a T ₂₄ of 18 compared to the comparative mainspring.
% Output torque is high. This also means that if the mainspring has the same output torque, the mainspring of the present invention can reduce the thickness of the mainspring compared to the comparative mainspring, so that the number of windings of the mainspring can be increased within a limited space of the barrel car, and Can extend the duration.

[0017]

[Table 4] Next, in order to examine the durability of the mainspring, an acceleration test was repeated in which the mainspring was fully wound and fully rewound, and the number of repetitions until the mainspring was broken was examined. Table 5 shows the number of repetitions until breakage of the spring in the present invention and the comparative spring. It can be seen that the spring of the present invention has a higher number of repetitions until breakage and is superior in durability as compared with the comparative spring. Further, as can be seen from the material composition, the spring of the present invention has a Cr and Mo content.
And a very high corrosion resistance.

[0018]

[Table 5]

[0019]

As described above, the mainspring of the present invention has a high output torque and is excellent in durability and corrosion resistance.
There is a great effect that it is optimal for use in small precision equipment.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of the shape of a power spring for a wristwatch.

FIG. 2 is a diagram illustrating an example of a manufacturing process of a mainspring.

FIG. 3 is a diagram showing a state in which the power spring for a wristwatch is inserted into a barrel car.

[Explanation of symbols]

 A spring main body B outer hook 1 spring main body 2 outer hook 3 barrel car 4 core

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI G04B 1/14 G04B 1/14 (72) Inventor Masato Okazaki 5-30-1, Nishitaga, Taihaku-ku, Sendai City, Miyagi Prefecture SII Co., Ltd.・ In the micropart (56) References JP-A-57-194237 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C22F 1/00 694 C22C 19/00 C22C 30/00 F16F 1/02 F16F 1/10 G04B 1/14

Claims (3)

(57) [Claims] 1. The composition is Co 30.9-37.2 by weight ratio.
%, Ni 31.4-33.4%, Cr 19.5-20.
5%, Mo 9.5 to 10.5%, Mn 0.1 to 0.5
%, Ti 0.3 to 0.7%, Fe 1.1 to 2.1%, N
b 0.8-1.2%, misch metal 0.01-0.0
In a process of manufacturing a mainspring using a Co-Ni-based alloy consisting of 2% and unavoidable impurities, an annealing process, a cold drawing process, a cold rolling process, a width cutting process, an edge polishing process, a cutting process, and a forming process A method for manufacturing a mainspring, comprising an aging treatment step, a welding step, and a Teflon vapor deposition step. 2. After the annealing step, the annealed wire is cold-drawn to a final working ratio of 30 to 90%, which is represented by a reduction ratio of a cross-section by drawing by an inverse tension wire drawing machine using a drawing die. 2. The method according to claim 1, further comprising a step.
Method of manufacturing the mainspring. 3. The method for manufacturing a mainspring according to claim 1, wherein the aging step is performed at a temperature of 400 to 620 ° C. in a vacuum or in a non-oxidizing atmosphere.