JP2008116205A - Mainspring, drive device and apparatus using the same, and method of manufacturing mainspring - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To establish a mainspring material using a carbon nanotube and a method of manufacturing a mainspring and improve reliability, achieve compactness, and facilitate manufacturing in a hairspring used as a power source and a drive device and an apparatus provided with the same. <P>SOLUTION: The hairspring is constituted of a compound material of graphite, amorphous carbon, and a carbon nanotube. The compound material of the mainspring can achieve high tensile strength and a low young's modulus and provide a hairspring which is compact and accurate in speed adjustment. By uniformly dispersing graphite, amorphous carbon, and a carbon nanotube in a medium and molding by extrusion molding or the like, it is possible to easily manufacture hairspring of uniform quality. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a mainspring used in a speed governor that regulates the rotation of a drive wheel train, a speed governor, a device, and a method for manufacturing the mainspring.

Conventionally, in a precision machine such as a timepiece, a mainspring has been used as a speed governor for controlling the rotation of a drive wheel train.
As such a spring material, conventionally, a work-hardening type or age-hardening type alloy has been used (Patent Document 1; spring for power source). When such an alloy material is used, the surface of the mainspring is treated with Teflon (registered trademark) in order to prevent the mainspring from sticking or rubbing.
Further, in order to reduce the size of the mainspring, a material having a small Young's modulus and a high tensile strength is preferable. As such a material, an amorphous metal material has been studied (Patent Document 2).
In recent years, a balance spring using carbon nanotubes has also been proposed (Patent Document 3).

Japanese Patent Laid-Open No. 9-13136 Japanese Patent No. 3498315 Japanese Patent Laid-Open No. 2002-341054

However, when a work-hardening or age-hardening type alloy is used as in Patent Document 1, the material is multi-component, and thus material non-uniformity is likely to occur. Further, such an alloy material has a drawback that a temperature change of a physical property value is large.
On the other hand, when an amorphous metal material is used as in Patent Document 2, pinholes are likely to be formed in the manufacturing process when amorphization is performed, and there is a problem for practical use and mass production. For this reason, it has been difficult to say that the amorphous metal material is suitable for a linear shape such as a spring or ribbon.
And about the spring which uses the carbon nanotube of patent document 3, the establishment of the usage and manufacturing method of a carbon nanotube waited, and it has not resulted in utilization.
In addition, it shows in the following table | surface about the characteristic of the mainspring manufactured with each mainspring material of patent document 1,2.

  Accordingly, an object of the present invention is to establish a spring material and a spring manufacturing method that can solve both of the above problems, and to provide a reliable and easy-to-manufacturing spring spring, a speed governor including the same, and a method for manufacturing the spring spring. Is to provide.

  The mainspring of the present invention is a mainspring used in a speed governing device for controlling the rotation of a driving wheel train that transmits driving force, and is composed of a composite material of at least graphite, amorphous carbon, and carbon nanotubes. It is characterized by.

  According to the present invention, it is possible to realize the structure of a composite material as a spring material using graphite (graphite), amorphous carbon, and carbon nanotubes (carbon nanofibers). By forming a spring from this composite material, A variety of advantages are obtained.

[1. Miniaturization of mainspring]
In the balance spring used to regulate the rotation of the drive wheel train, in order to achieve the predetermined mechanical energy required for the regulation, it is possible to increase the length of the mainspring or increase the thickness of the mainspring. Although it is conceivable, this method inevitably increases the size of the mainspring when the mechanical energy of the mainspring is increased.
On the other hand, in the present invention, since the Young's modulus of the composite material is small and the tensile strength is large, the mechanical energy of the mainspring can be increased regardless of the number of turns and the thickness of the mainspring. Thereby, the mainspring can be reduced in size without changing the overall shape of the speed governor including the mainspring.
As described above, in the present invention, it is possible to satisfy both the realization of the predetermined mechanical energy and the miniaturization as the speed control spring by increasing the mechanical energy by the composite material.

[2. Low Young's modulus]
In addition to the high tensile strength described above, the present invention has a low Young's modulus of the composite material. Therefore, the synergistic effect of the high tensile strength and the low Young's modulus improves the mechanical energy as a speed control spring. Can be secured, and further miniaturization can be achieved.
Further, in the present invention, since the Young's modulus of the composite material is small, the toughness of the mainspring can be secured.

[3. Uniformity of each material]
Since the graphite, amorphous carbon, and carbon nanotube constituting the composite material of the present invention are dispersed in the medium at the time of blending and become uniform, the desired properties of the mainspring can be realized and the reliability can be improved.

[4. Easy to mold]
In the present invention, the pre-fired member prepared by mixing graphite, amorphous carbon, and carbon nanotubes can be easily formed into a linear body having a thickness required for the mainspring by extrusion molding or the like.

[5. Non-magnetic]
Graphite, amorphous carbon, and carbon nanotubes are all carbon materials and are non-magnetic, so that the restrictions in laying the spring in the device are relaxed. That is, an electromagnetic circuit having a generator or the like and a mainspring can be arranged close to each other. Further, it is possible to prevent the mainspring from being pulled by the external magnetic field and the properties of the mainspring to deteriorate.

[6. Corrosion resistance]
Since graphite, amorphous carbon, and carbon nanotubes are carbon materials and have excellent corrosion resistance, it is not necessary to form a protective film on the mainspring surface.

[7. lightweight]
Since the composite material composed of graphite, amorphous carbon, and carbon nanotube, which is a carbon material, has a small density and is lightweight, when the spring of the present invention is incorporated in a device or the like, it can contribute to the portability of the device.
Further, since it is lightweight, it is advantageous at the time of a drop impact, and the mainspring characteristic does not change due to a change in posture when carrying the device, and it is unnecessary to design in consideration of deformation due to the weight of the mainspring. That is, the speed control by the mainspring becomes stable, and the driving accuracy can be improved.

[8. Temperature characteristics]
The composite material composed of graphite, amorphous carbon, and carbon nanotubes has a smaller thermal expansion coefficient and higher thermal stability than amorphous metal materials and the like. The composite material has excellent temperature characteristics in both mechanical characteristics and physical characteristics, and since there is little change in Young's modulus due to temperature change, the speed control by the mainspring becomes stable, and the driving precision of the driving wheel train can be improved. .

[9. Environmental protection]
Since the composition of the composite material is only a renewable carbon material that circulates in nature, it can contribute to environmental protection as compared with the case of using a metal material or the like.

[10. Improved material design freedom]
In addition to the above, in the composite material, the tensile strength and Young's modulus can be set in a wide range as compared with other materials.
That is, Young's modulus over a wide range can be realized by changing the blending ratio of graphite and amorphous carbon and firing conditions, and by combining carbon nanotubes with these graphite and amorphous carbon, Young can be made variable by graphite and amorphous carbon. It becomes possible to improve the tensile strength over the entire range of the rate.
As a result, the composite material of the present invention can be used as a spring material requiring tensile strength, and the tensile strength and Young's modulus of the composite material can be set in a wide range, thereby greatly improving the design freedom of the spring material. become.
Here, the tensile strength of the composite material composed solely of graphite and amorphous carbon is about 0.05 to about 0.7 GPa, and the Young's modulus is about 10 to about 200 GPa. Thus, it is possible to greatly improve the tensile strength from about 1.0 to about 1.5 GPa while maintaining the characteristic of changing the rigidity by only graphite and amorphous carbon.
The strength of the general carbon material is about 0.02 to 0.1 GPa, and the Young's modulus is about 4 to 20 GPa. FIG. 7 shows the relationship between the Young's modulus and the tensile strength of the composite material of the present invention.

In the mainspring of the present invention, it is preferable that the axial direction of the carbon nanotube is aligned with the circumferential direction around which the mainspring is wound.
According to this invention, since the carbon nanotube which is a cylindrical body is orientated along the circumferential direction of the mainspring, the tensile strength can be further increased.

In the mainspring of the present invention, it is preferable that amorphous carbon is larger than graphite in the weight composition of the composite material.
According to the present invention, in the weight composition, the Young's modulus can be reduced by making the composition ratio of graphite in the composite material smaller than the composition ratio of amorphous carbon, so that the toughness of the mainspring as the structural material can be ensured better.

In the mainspring of the present invention, it is preferable that the cross-sectional area of the mainspring is changed in the length direction of the mainspring.
According to the present invention, it is possible to change the cross-sectional area of the mainspring element in the length direction of the mainspring element, thereby controlling the urging force of the mainspring.
In addition, after preparing the raw material of the composite material, the cross-sectional area of the mainspring can be easily controlled by forming a linear body by performing extrusion molding or the like, and changing conditions such as discharge speed and pressure at this time. .

The speed governing device of the present invention includes the above-described spring and a balance that is biased by the spring.
According to this invention, by providing the above-described mainspring, various effects similar to the above-described effects can be enjoyed.

A device according to the present invention includes the above-described speed governor and a drive wheel train that transmits a driving force, and the rotation of the drive wheel train is regulated by the speed governor.
According to the present invention, various effects similar to those described above can be enjoyed.
In particular, since the mainspring has a low Young's modulus and a high tensile strength, the change in Young's modulus with a change in temperature is small, and since the mainspring characteristics are stable with respect to the light weight, the speed can be adjusted with high accuracy. Thereby, the drive precision of the drive wheel train controlled by the speed governor can be improved.
Further, since the mainspring included in the speed governor is small and light, it is possible to promote downsizing and weight reduction of the device.
Further, the adoption of the composite material facilitates the material design and manufacture of the mainspring, so that the manufacturing cost of the device can be reduced and the reliability can be improved.

The device according to the present invention is preferably configured as a timepiece including a time measuring unit configured to include the speed control device and an indicating member that is driven by the driving wheel train and indicates time.
As described above, the above-described effect can be further increased by incorporating a speed governor equipped with a balance spring having a small size, light weight, high accuracy, and high reliability into a precision instrument such as a watch.

  The manufacturing method of the mainspring used in the speed governor for controlling the rotation of the drive wheel train of the present invention includes a raw material preparation step for uniformly dispersing a carbonizable organic object and carbon nanotubes, and the dispersed organic object And a carbon nanotube are formed into a linear body by extrusion, a shape imparting process for imparting a spring shape to the linear body, and the linear body to which the spring shape is imparted in an inert atmosphere. And a carbonization step in which carbonization is performed by heat treatment.

According to this invention, a low Young's modulus and a high tensile strength can be realized by blending carbon nanotubes with an organic substance in the raw material blending step. Thereby, while being able to ensure the toughness of the balance spring, it is possible to provide a balance spring having excellent temperature characteristics and high accuracy of the regulation, which can realize a predetermined mechanical energy required for the regulation while being small.
In the raw material preparation step, a bonding agent such as a furan resin, a plasticizer, or the like may be used.
Here, as the organic object, it is preferable to employ two or more carbon materials such as graphite and amorphous carbon. Thereby, since the value which tensile strength and Young's modulus can take in a wide range, the freedom degree of material design can be made high, and a favorable temperature characteristic is obtained in each of a mechanical characteristic and a physical characteristic.

In addition, since the size of the cross-sectional area of the linear body can be controlled by conditions such as pressure and discharge speed during extrusion molding in the extrusion molding step, it is possible to control the biasing force of the balance spring. In addition, since a carbon material is suitable for this extrusion molding, workability can be made favorable.
Furthermore, since the mainspring material in the present invention contains carbon nanotubes in an organic substance and is very excellent in heat resistance, it can be fired at a high temperature and can be firmly baked.
As described above, a spring manufacturing method using an organic object and a carbon nanotube has been established. By manufacturing a balance spring using this manufacturing method, the size and weight can be reduced, the operation time can be extended, the manufacturing can be facilitated, and the reliability can be improved. It is possible to provide a balance spring having various advantages such as improved performance. It can also be used for mass production.

  According to the present invention, a spring material using amorphous carbon and carbon nanotubes, or a spring manufacturing method using an organic object and carbon nanotubes can be established, and a balance spring used in a speed governor, a speed governor including the balance spring, and This contributes to reducing the size and weight of devices, improving reliability, and facilitating manufacturing.

Embodiments of the present invention will be described below with reference to the drawings. This embodiment is a mechanical timepiece.
FIG. 1 shows a barrel as a driving device provided in the mechanical timepiece of the present embodiment, and FIG. 2 shows a speed governing device that regulates a driving wheel train that transmits driving force from the barrel.

[1. Configuration of barrel
As shown in FIG. 1, the mechanical timepiece of the present embodiment includes a barrel 1 composed of a mainspring 1a as a power source, a barrel gear 1b, a barrel complete 1c, and a barrel lid 1d. The mainspring 1a has an outer end fixed to the barrel gear 1b and an inner end fixed to the barrel complete 1c.
The barrel 1c is formed into a cylindrical shape and is inserted into the support member 2 so that the barrel 1c is supported in a cantilever state by the base plate 3 via the support member 2 and is screwed into the support member 2 At the same time it is pressed so as not to come out upward in the figure, it also has rattles (foot scratches) in the cross-sectional direction. Such a support member 2 has a flange portion 2a on the ground plate 3 side, and is fixed to the ground plate 3 by caulking the lower peripheral edge of the flange portion 2a in the figure, so that it is more difficult to fall down.
Between the barrel complete 1 and the main plate 3, a square hole wheel 4 that rotates integrally with the barrel complete 1c is arranged. The square hole wheel 4 has a center hole having a square shape or a track shape, and the center hole is inserted into a rectangular portion (corner portion) of the barrel 1c and the locking portion 1e of the barrel 1c and the main plate. 3 and is arranged in a so-called throwing structure.

[2. Drive wheel train configuration]
FIG. 1 and FIG. 2 show a driving wheel train that transmits the driving force by the barrel.
The rotation of the barrel gear 1b is transmitted to the pinion 6a of the second wheel 6 and then accelerated from the gear 6b of the second wheel 6 to the pinion of the third wheel (not shown). Then, the speed is increased from the gear 8b of the fourth wheel 8 to the pinion 8a of the fourth wheel 8 via the car 9 and transmitted to the pinion 10a of the car 10.
Here, the driving wheel train for transmitting the driving force of the mainspring 1a as a power source is constituted by the barrel gear 1b to the car 10.
The second wheel 6 is fixed with a cylindrical pinion 6c, the cylindrical pinion 6c is fixed with a minute hand (indicating member), and the fourth wheel 8 is fixed with a second hand (indicating member) not shown.

As shown in FIG. 2, the car 10 meshes with an escape wheel 21 and transmits power from the mainspring 1 a to an escapement device 20 including an escape wheel 21 and an ankle 22.
Reference numeral 24 in the figure is an ankle receiver.

[3. Configuration of governor]
In the mechanical timepiece of this embodiment, a time standard is created by the escapement device 20 composed of the escape wheel 21 and the ankle 22 described above, and the speed governor 30 composed of the balance 31 and the balance spring 32, and It functions as a timer.
The spring of the present invention is used as the balance spring 32 that urges the balance 31 of the speed governor 30.

3 and 4 show the speed governor 30 more specifically.
The balance 31 is configured to include a tension stem 311, a tension wheel 312, a swing seat 313, a mustache ball 314, a mustache holder 315, and a slow / fast needle 316.
A ten wheel 312, a swing seat 313, and a beard ball 314 are fixed to the tenshin 311, and are configured to rotate integrally.
The balance spring 32 has an inner peripheral end fixed to the beard ball 314 and an outer peripheral end fixed to the mustache holder 315.
The slow / fast needle 316 includes a mustache rod 316A and a mustache receptacle 316B, and the outermost peripheral portion of the mustache spring 32 passes between the mustache rod 316A and the mustache receptacle 316B.

In such a speed adjusting device 30, when the ten wheel 312 rotates about the tenth true 311, the whisker ball 314 also rotates with this, so that the urging force of the balance spring 32 acts on the ten wheel 312. When the urging force balances with the inertial force of the ten wheel 312, the rotation of the ten wheel 312 is stopped, and the ten wheel 312 rotates in the reverse direction by the urging force of the balance spring 32. That is, the ten wheel 312 repeats rocking about the tenth true 311 as an axis.
The swinging cycle of the tenn ring 312 can be changed by finely adjusting the positions of the hair rod 316A and the hair support 316B of the slow / fast needle 316.

[4. Mainspring configuration]
Here, the balance spring 32 used in the speed governor 30 is formed in an Archimedean spiral, and the dimensions of the strands of the balance spring 32 are about 1 mm in width, about 0.1 mm in thickness, and about 300 mm in total length. .
Further, the cross-sectional area of the balance spring 32 strand is a circle having a diameter of about 0.2 mm in the present embodiment, but may be any shape such as an ellipse or a rectangle.
In addition, regarding the thickness of the strands of the balance spring 32, although not shown, the sectional area of the strands on the inner end side is larger than the sectional area of the strands on the outer end side.

Here, the balance spring 32 is composed of a composite material of graphite, amorphous carbon, and carbon nanotube, and this composite material has a high tensile strength and a low Young's modulus.
In the weight composition of the balance spring 32 composite, amorphous carbon is made larger than graphite. The carbon nanotubes are oriented so that the axial direction thereof is aligned with the circumferential direction around which the balance spring 32 is wound.

  The material having a high tensile strength and a small Young's modulus is used for the balance spring 32 in view of the realization of a predetermined tensile strength necessary for biasing and adjusting the balance as follows. It is to be guided.

[5. Spring material design concept]
[5-1 Adjusting the spring thickness and overall length based on the proportional relationship between the number of turns and the output torque]
Conventionally, it is known that the relationship between the number of turns of the mainspring and the output torque can be regarded as approximating a proportional relationship as indicated by G6 in FIG. That is, suppose that the torque output by the mainspring is T, the number of times the mainspring is wound (number of turns) is N, the Young's modulus is E, the total length of the mainspring is L, and the mainspring has a rectangular cross section with a thickness t and a width b. ,
T = (Et ³ bπ / 6L) × N (1)
It is expressed by the formula.

On the other hand, the total length L, the thickness t, and the width b of the mainspring are determined by the barrel size in which the mainspring is accommodated. When the radius inside the barrel is R and the true radius of the barrel is r, the total length L of the mainspring is
L = π (R ² −r ² ) / 2t (2)
It can be seen that the total length L and the thickness t of the mainspring are in an inversely proportional relationship.

The mechanical energy stored in the mainspring is given by integrating the output torque T in equation (1) by the number of turns N, and since equation (1) is also considered as a function of the total length L and thickness t of the mainspring, The energy of the mainspring was adjusted by adjusting L and t.
However, in the method of adjusting the mechanical energy of the mainspring only by the thickness t and the total length L of the mainspring as described above, when the mechanical energy is increased, the mainspring is increased in size. For example, when the total length L of the mainspring is increased, the maximum number of turns Nmax of the mainspring is increased, the mainspring is increased in the radial direction, and when the thickness t of the mainspring is increased, the mainspring is similarly increased in the radial direction.

[5-2 Correlation between mainspring deflection and mainspring mechanical energy]
Here, the deflection of the spring (thickness t, width b, length L) in which the relationship of the above-described formula (1) is established, the inner end is rigidly joined to the beard ball 314 as shown in FIG. It is approximately obtained as a deflection of a cantilevered support beam in which the outer end serving as the other end is a free end. The deflection angle α (rad) in FIG. 6 is given by assuming that the spring deflection radius is r.
r = L / α (3)
It can be expressed as.

On the other hand, the number of turns N of the mainspring is determined by the deflection angle α described above.
N = α / 2π (4)
It is expressed.
Therefore, the above equation (1) is derived from the equations (3) and (4).
T = (bt ³ E / 12L) × α (5)
And transformed.

The energy U stored by the spring deflection is obtained by integrating the bending moment acting on the spring, that is, the output torque T of the spring with respect to α,
U = ∫Tdα = ∫ (bt ³ E / 12L) × αdα = (bt ³ E / 24L) × α ² (6)
It becomes.
Therefore, when the maximum energy Umax that can be stored in the spring having the length L is the maximum deflection angle αmax of the spring in FIG.
Umax = (bt ³ E / 24L) × αmax ² (7)
It is expressed.

[5-3 Correlation between bending stress acting on spring and output torque]
Here, the bending stress σ acting on the mainspring is expressed as a function of the bending moment acting on the mainspring, that is, the output torque T that can be output by the mainspring in the bent state, and the displacement in the thickness direction from the neutral axis A of the mainspring. Is y, and the spring moment of inertia is Iz.
σ = T × y / Iz (8)
It is expressed.
Therefore, the maximum bending stress σb in the tensile direction acting on the upper surface of the mainspring in FIG.
σb = T · (t / 2) / Iz (9)
Is calculated.

On the other hand, assuming that the cross section of the mainspring has a rectangular shape having a thickness t and a width b,
Iz ＝ bt ³ /12… （10）
From the equations (9) and (10),
^{T = (bt 2/6)} × σb ... (11)
It is expressed.
Therefore, from equations (1) and (11),
^{T = (Et 3 bπ / 6L} ) × N = (bt 2/6) × σb ... (12)
The maximum number of turns Nmax of the mainspring that gives the maximum deflection angle αmax in the equation (7) is calculated from the equation (4):
Nmax = αmax / 2π (13)
It becomes. Therefore, from equations (12) and (13),
αmax = 2Lσb / Et (14)
This relationship can be derived.
Therefore, the maximum deflection angle αmax is determined by the maximum bending stress σb in the tensile direction of the mainspring, that is, the maximum tensile stress σmax of the mainspring material used for the mainspring, and the above-described equation (7) is
Umax = (bt ³ E / 24L) × (2Lσmax / Et) ² = (btL / 6) × (σmax ² / E) (15)
It can be seen that

[5-4 Correlation between maximum tensile force and Young's modulus and maximum energy of mainspring]
From equation (15), the maximum energy Umax stored in the mainspring of FIG. 6 varies not only with the thickness t, width b, and length L of the mainspring, but also with the maximum tensile stress σmax and Young's modulus E of the material constituting the mainspring. I know that
Therefore, it can be seen that in order to further increase the energy Umax stored in the mainspring, it is preferable to use a material having a property of a large maximum tensile stress σmax and a small Young's modulus E for the mainspring.

  The swing period T of the balance wheel 312 changes not only by the moment of inertia J of the rotating portion of the balance wheel 312 or the like, but also by the material characteristics of the spring, and the width of the balance spring is b, the thickness is t, and the spring. When the length is L and the Young's modulus of the balance spring is E, it is expressed by the following equation (16).

[6. Structure of mainspring material]
Based on the above, in the present embodiment, the following is used as a raw material for the balance spring 32.
20% by weight of furan resin
Graphite powder 10% by weight
40% by weight of amorphous carbon powder
Carbon nanotube 20% by weight
Dioctyl phthalate 10% by weight

  In the weight composition of the mainspring material, it becomes brittle when the composition ratio of graphite is larger than the composition ratio of amorphous carbon. Therefore, by setting the composition ratio of amorphous carbon larger than the composition ratio of graphite, the balance spring 32 can be reliably used as a structural material. To work.

Here, FIG. 7 shows the relationship between Young's modulus and tensile strength of various materials. “PFC” shown in FIG. 7 is plastic formable carbon such as plastic. This PFC has a wide range of characteristics by changing the compounding ratio of graphite and amorphous carbon and the firing conditions. There is an advantage that a material of However, the tensile strength was insufficient for use as a spring.
The tensile strength of the composite material composed of only graphite and amorphous carbon as the PFC is about 0.05 to about 0.7 GPa, and the Young's modulus is about 10 to about 200 GPa, that is, the blending ratio of graphite and amorphous carbon and A wide range of Young's modulus can be realized by changing the firing conditions. Taking advantage of the characteristics of the composite material of graphite and amorphous carbon, and improving the tensile strength over the entire range of Young's modulus, which can be changed by graphite and amorphous carbon, by making a composite material with carbon nanotubes added. (See the thick solid line “present invention” in FIG. 7).
That is, a wide range of Young's modulus and tensile strength can be realized, and the degree of freedom in material design is expanded.

The sizes of the graphite powder, the amorphous carbon powder, and the amorphous carbon in the raw material are as follows in the present embodiment.
Graphite powder Average particle size 2μm
Amorphous carbon powder Average particle size 2μm
Carbon nanotube diameter 10nm, length 10μm

The diameter of the carbon nanotube is preferably 1 nm to 50 nm. That is, when the diameter of the carbon nanotube is less than 1 nm, a desired reinforcing effect for use as a balance spring cannot be obtained, and when it exceeds 50 nm, the main material in the linear body obtained in the subsequent extrusion step S2 This will impede the orientation.
Further, the length of the carbon nanotube is preferably 0.5 μm to 50 μm. That is, when the length of the carbon nanotube is less than 0.5 μm, a desired reinforcing effect for use as a balance spring cannot be obtained, and when it exceeds 50 μm, the orientation of the carbon nanotube itself becomes difficult, and again Since the orientation is hindered, the strength cannot be improved.

[7. Wind-up spring manufacturing method]
The balance spring 32 is manufactured using the above raw materials.
FIG. 8 shows a manufacturing process of the balance spring 32.
[7-1 Raw material preparation process]
In the raw material blending step S1, the above raw materials, that is, furan resin as a thermosetting resin, graphite powder, amorphous carbon powder, carbon nanotube, and dioctyl phthalate as a plasticizer are uniformly dispersed using a Henschel mixer. Here, each raw material tends to be uniform depending on the average particle diameters of the graphite powder and the amorphous carbon powder and the size of the carbon nanotubes.
And kneading | mixing is repeated with respect to the raw material disperse | distributed uniformly in this way, and a sheet-like composition is obtained. In the case of kneading, a two roll for mixing whose surface temperature is kept at about 120 ° C. is used.

[7-2 Extrusion molding process]
In the extrusion molding step S2, vacuum extrusion molding is performed from the sheet-like composition obtained in the raw material blending step S1 with a plunger type hydraulic extrusion molding machine at a discharge speed of about 3 m / sec. As a result, a linear body having a diameter of about 0.3 mm is obtained.
Here, it is possible to change the cross-sectional area of the linear body by changing the pressure at the time of extrusion molding, the discharge speed, etc., and arbitrarily change the cross-sectional area of the linear body in the length direction of the linear body It can be set. .

[7-3 Shape assignment process]
Next, in the shape imparting step S3, the linear body obtained in the extrusion step S2 is wound around a spiral carbonaceous support substrate (jig) and shaped. Thereby, a stable mainspring shape is given to the linear body.

[7-4 Firing (carbonization) process]
In the firing (carbonization) step S4, the linear body wound around the support base material (jig) is heated at atmospheric pressure for about 10 hours in a clean oven heated to 180 ° C. (around ± 5 ° C.). To do. By heating the linear body, a carbon precursor is obtained. This carbon precursor has a porous shape by removing furan resin and dioctyl phthalate prepared as raw materials by heating.

Furthermore, the carbon precursor is carbonized and densified by heating the carbon precursor to about 2000 ° C. in a vacuum. By heating at an ultimate temperature of about 2000 ° C. in this way, the porous carbon precursor can be securely baked and densified.
Here, the ultimate temperature at the time of carbonization can be suitably set in the range of about 1500 to about 2000 ° C.

In addition, the heating rate from the heating temperature of about 180 ° C. when obtaining the carbon precursor to the heating temperature of about 2000 ° C. when carbonizing can be set to about 10 ° C./min. Therefore, the holding time may not be set, but may be set to about 1 hour, for example.
Further, the cooling after the heating may be furnace cooling.

As a result of the firing (carbonization) step S4, a balance spring 32 having a desired shape made of a composite material of graphite, amorphous carbon, and carbon nanotubes was obtained.
The balance spring 32 thus obtained had a Young's modulus of about 100 GPa and a tensile strength of about 1.5 GPa.
The characteristics of the balance spring 32 obtained as described above are shown in the following table in comparison with the characteristics of the mainsprings of Patent Documents 1 and 2 described above, which are different in material from the balance spring 32.

[8. Effects of this embodiment]
According to the present embodiment as described above, the composite material of graphite, amorphous carbon, and carbon nanotube is used as the material of the balance spring 32 used in the speed control device of the electronically controlled mechanical timepiece. Various effects can be obtained.

(1) As described above, a spring material and a manufacturing method using graphite, amorphous carbon, and carbon nanotubes have been established.
The balance spring 32 formed from this spring composite material has a tensile strength greatly improved by the blending of the carbon nanotubes, so that the mechanical energy of the balance spring 32 is greatly increased regardless of the number of turns and the thickness of the balance spring 32. Thus, the speed governor 30 including the balance spring 32 can be downsized.

(2) Since the Young's modulus of the composite material is small, the toughness of the balance spring 32 can be secured.

(3) Since the graphite, amorphous carbon, and carbon nanotube constituting the composite material are dispersed and made uniform using furan resin or dioctyl phthalate as a medium at the time of raw material preparation, the desired characteristics of the balance spring 32 can be realized, and reliability Can be improved.

(4) Graphite, amorphous carbon, and carbon nanotubes, which are carbon materials, are suitable for extrusion molding, and are required for the balance spring 32 by extruding from a sheet-like composition prepared by mixing these graphite, amorphous carbon, and carbon nanotube. A linear body having a desired thickness can be easily formed.

(5) Since graphite, amorphous carbon, and carbon nanotubes are all non-magnetic, the balance spring 32 can be easily laid out in the movement without adopting a magnetic resistance structure. Further, it is possible to prevent the balance spring 32 from being pulled by an external magnetic field and the characteristics of the balance spring 32 from being deteriorated.

(6) Since graphite, amorphous carbon, and carbon nanotubes are all excellent in corrosion resistance, formation of a protective film on the surface of the balance spring 32 can be eliminated.
In addition, the self-lubricating properties of these graphite, amorphous carbon, and carbon nanotubes can prevent rubbing between the strands of the balance spring 32.

(7) Since graphite, amorphous carbon, and carbon nanotubes are carbon materials, the composite material has a small density and is lightweight, which can contribute to portability as a watch or a pocket watch. Moreover, since it is lightweight, it is excellent in impact resistance, and it becomes unnecessary to design in consideration of deformation due to the weight of the balance spring 32.

(8) The composite material composed of graphite, amorphous carbon, and carbon nanotubes has higher thermal stability than an amorphous metal material or the like. The composite material is excellent in temperature characteristics in both mechanical characteristics and physical characteristics, and has little change in Young's modulus due to temperature change, so that the speed adjustment by the balance spring 32 can be performed with high accuracy. That is, the use of the speed governor 30 including the balance spring 32 is advantageous for a timepiece in which accuracy is important.

(9) Since the composite material used as the material of the balance spring 32 is composed of a carbon material, it can contribute to environmental protection as compared with the case of using a metal material or the like.

(10) In the composite material, since the tensile strength and Young's modulus can be set wider than other materials, the degree of freedom in designing the balance spring 32 material can be remarkably improved.

(11) Since the carbon nanotubes that are cylindrical bodies are oriented along the circumferential direction of the balance spring 32, the tensile strength of the balance spring 32 can be further increased.

(12) Since the amorphous carbon is larger than the graphite in the weight composition of the composite material, the Young's modulus of the balance spring 32 can be reduced, and the toughness of the balance spring 32 as a structural material can be ensured better.

(13) Since the size of the cross-sectional area of the linear body can be easily controlled during extrusion molding in the extrusion molding step S2, and the cross-sectional area of the strands of the balance spring 32 can be changed, It becomes possible to control the urging force of the balance spring 32.

(14) Since the material design and manufacture of the balance spring 32 are facilitated by employing the composite material, the manufacturing cost of the speed governor 30 can be reduced and the reliability can be improved.

(15) The composite material includes carbon nanotubes blended into an organic substance and is extremely excellent in heat resistance. Therefore, the composite material can be fired at a high temperature, and the carbon precursor can be firmly baked.

  In the present embodiment, the mainspring 1a as the power source can also be formed of a composite material similar to the balance spring 32, and both the balance spring 32 and the mainspring 1a are formed of the composite material. Thus, the above-described effect can be further increased.

[Modification of the present invention]
The present invention is not limited to the above-described embodiment.
In the above embodiment, the timepiece is exemplified as a device provided with a speed control device using the mainspring of the present invention. However, the present invention is not limited to this, and a music box that plays music at a constant speed can also be exemplified.

The balance spring used in the speed governor has been exemplified above, but the composite material constituting the mainspring of the present invention and the mainspring manufacturing method described above are used as a power source in a mechanical timepiece or an electronically controlled timepiece. Can also be used.
Furthermore, from a composite material similar to the mainspring composite material of the present invention, a spring for fixing a quartz oscillator of a quartz oscillation type electronic timepiece in a biased state by a method similar to the spring manufacturing method of the present invention, Can be manufactured. You may comprise the cork which meshes with the square wheel 4 of the said embodiment from the mainspring composite material of this invention.

The mainspring composite material of the present invention only needs to be configured to include at least graphite, amorphous carbon, and carbon nanotubes, and it is a matter of course that the blending ratio and mode of the weight composition and the like are not limited to the above embodiment.
Further, the shape of the mainspring of the present invention, the width, thickness, cross-sectional area, total length, maximum number of turns, Young's modulus, tensile strength, etc. of the main wire are also appropriately determined without being limited to the above embodiment. The mainspring of the above embodiment has a circular spiral shape in plan view, but is not limited thereto, and may be a spiral shape in plan view elliptical shape, for example.
Furthermore, in the mainspring manufacturing method of the present invention, the method of dispersing each raw material, the method of forming a linear body, and the firing conditions such as the heating temperature are not limited to the above embodiment.

Sectional drawing which shows the drive device (barrel box) in the mechanical timepiece which is embodiment of this invention. Sectional drawing which shows the escapement apparatus and speed control apparatus of the said mechanical timepiece. The top view which shows the speed control apparatus of the said mechanical timepiece. Sectional drawing which shows the speed control apparatus of the said mechanical timepiece. The graph showing the relationship between the number of turns of the mainspring and the output torque. The schematic diagram for demonstrating the view of a spring material design. The graph which shows the relationship between the Young's modulus and tensile strength of this invention. The flowchart which shows the manufacturing process of the mainspring in the above-mentioned embodiment.

Explanation of symbols

1b ... barrel wheel, 6 ... second wheel, 8 ... fourth wheel, 9 ... car, 10 ... car, 20 ... escape device, 30 ... speed governor , 31 ... balance, 32 ... balance spring, S1 ... raw material preparation step, S2 ... extrusion molding step, S3 ... shape application step, S4 ... firing (carbonization) step.

Claims (8)

A spring used in a speed governing device for controlling the rotation of a driving wheel train that transmits driving force,
A mainspring comprising at least a composite of graphite, amorphous carbon, and carbon nanotubes. In the mainspring according to claim 1,
The spring having the axial direction of the carbon nanotube aligned in the circumferential direction around which the spring is wound. In the mainspring according to claim 1 or 2,
In the weight composition of the composite material,
A mainspring characterized by amorphous carbon being larger than graphite. In the mainspring according to any one of claims 1 to 3,
The mainspring is characterized in that the cross-sectional area of the mainspring is changed in the length direction of the mainspring. A mainspring according to any one of claims 1 to 4,
A speed control device comprising: a balance biased by the mainspring. A governing device according to claim 5;
A driving wheel train that transmits driving force,
The rotation of the drive wheel train is regulated by the governor. The device according to claim 6 is:
A time measuring unit configured to include the speed governor;
An indicator member that is driven by the drive wheel train and indicates time;
A device that is configured as a watch. A raw material preparation step for uniformly dispersing carbonizable organic matter and carbon nanotubes;
An extrusion process for forming the dispersed organic body and carbon nanotubes into a linear body by extrusion;
A shape application step for applying a spring shape to the linear body;
And a carbonization step in which the linear body having the spring shape is heated and carbonized in an inert atmosphere, and is used in a speed governor for controlling the rotation of a drive wheel train. Wind-up spring manufacturing method.

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