JP2014142326A - Balance, movement for watch, watch, and manufacturing method for balance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a balance not required to perform the re-adjustment of a rate, not reducing rotation balance and rotation performance, and capable of simply and highly accurately performing the temperature adjustment of an inertia moment.SOLUTION: A balance includes: a balance staff 41 rotatably pivoted; a balance wheel 42 whose one end is a fixed end fixed to a coupling arm 51 which is coupled to the balance staff 41 in a radial direction and the other end is a free end deformable in a radial direction. The balance wheel 42 includes: a first rim 54 located inside the radial direction and fixed to the coupling arm 51; and a second rim 55 arranged to overlap with an outer periphery of the first rim 54 and composed of a material different from that of the first rim 54 in coefficient of linear expansion. The first rim 54 and the second rim 55 are defined as a balance 40 joined by a melting part which melts mutual materials.

Description

  The present invention relates to a balance with a balance, a timepiece movement including the balance, a timepiece, and a method for producing a balance.

A governor of a mechanical timepiece is generally composed of a balance with a balance and a hairspring. Of these, the balance with a balance and a balance wheel fixed to the balance is a member that periodically vibrates and vibrates around the rotation axis of the balance. At this time, it is important that the vibration cycle of the balance with hairspring is set within a predetermined value. This is because if the vibration period deviates from the specified value, the rate of the mechanical timepiece (timepiece delay, degree of advancement) changes. However, the vibration cycle is likely to change due to various causes, and for example, changes due to temperature changes.
Here, the vibration period T is expressed by the following equation (1).

  In the above formula (1), I represents “the moment of inertia of the balance”, and K represents “the spring constant of the hairspring”. Therefore, when the moment of inertia of the balance or the spring constant of the hairspring changes, the vibration period also changes.

  Here, the metal material used for the balance with hairspring is generally a material having a positive coefficient of linear expansion, and expands as the temperature rises. As a result, the balance wheel expands in diameter and increases the moment of inertia. Moreover, since the Young's modulus of the steel material generally used for the hairspring has a negative temperature coefficient, the spring constant is lowered by the temperature rise.

As described above, when the temperature rises, the moment of inertia increases and the spring constant of the mainspring decreases. Therefore, as apparent from the above formula (1), the vibration period of the balance with hairspring becomes a characteristic that is short at a low temperature and long at a high temperature. For this reason, the time characteristic of the timepiece is such that it proceeds at a low temperature and is delayed at a high temperature.
Then, the following two methods are known as a countermeasure for improving the temperature characteristic of the vibration cycle of the balance with hairspring.

  As a first method, by adopting a constant elastic material such as coelin bar as a material for the hairspring, the temperature coefficient of Young's modulus near the operating temperature range of the watch (for example, 23 ° C. ± 15 ° C.) is positive. It is a method. As a result, the change in the moment of inertia of the balance with respect to the temperature can be canceled within the above operating temperature range, and the temperature dependence of the vibration cycle of the balance can be kept low.

  As a second method, a part of the plurality of rims constituting the balance wheel is made of a material having different thermal expansion coefficients in which one end in the circumferential direction is a fixed end and the other end in the circumferential direction is a free end. A method using a bimetal obtained by joining metal plates in the radial direction is known (see Non-Patent Document 1).

  Among the bimetals, for example, a low thermal expansion material such as invar is used as the material of the metal plate located on the radially inner side, and a high thermal expansion material such as brass is used as the material of the metal plate located on the radially outer side. By doing so, when the temperature rises, the bimetal deforms inward so that the free end side moves inward in the radial direction due to the difference in thermal expansion coefficient. As a result, the average diameter of the rim portion can be reduced to reduce the moment of inertia, and the temperature characteristic of the moment of inertia can have a negative slope. As a result, the temperature dependency of the vibration period of the balance with hairspring can be kept low.

Swiss University of Watchmaking, "The Theory of Horology", English version 2nd edition, April 2003, p136-137

  However, in the first method described above, when the balance spring is made of a constant elastic material such as coelin bar, the temperature coefficient of Young's modulus may greatly change depending on various processing conditions such as composition at the time of melting and heat treatment. Therefore, a strict manufacturing control process is required, and it is not easy to manufacture the hairspring. Therefore, it may be difficult to make the temperature coefficient of Young's modulus positive near the operating temperature range of the watch.

  Further, in the second method described above, as a method of constructing a balance wheel, an annular metal member made of a high expansion material is preferably placed on the outer periphery of a metal member made of a low expansion material located radially inside. After brazing with the material, the balance wheel is formed by turning, so the amount of brazing material is not constant due to the clearance between parts, and the moment of inertia when formed on the balance wheel varies greatly. It was. Also, deviation between radial parts is likely to occur, and when formed on a balance wheel, the ratio of the plate thickness of the low thermal expansion part to the high thermal expansion part is not constant at the plurality of rim parts, and free ends due to temperature changes. There was a problem that the amount of deformation of fluctuated.

  As another method for constructing the balance wheel, an annular high expansion material having a melting point lower than that of the low expansion material is arranged outside the low expansion material finished to a predetermined outer diameter, and only the high expansion material is provided. There is a method of forming a balance wheel by turning after joining a high expansion material to a low expansion material by heating at a melting temperature. In this method, no brazing material is interposed between the low-expansion material and the high-expansion material, so there is no fear that the variation in the moment of inertia will increase. Since the outer diameter processing of the high expansion material is a separate process, it is difficult to make the ratio of the plate pressure of each material constant, and there is a problem that the amount of deformation of the free end due to temperature change varies. Furthermore, in both of the manufacturing methods, it is necessary to heat the brazing material or the high expansion material to a high temperature of, for example, 800 ° C. or higher, so that a large residual stress remains due to the difference in the linear expansion coefficient of the material during cooling. Moreover, since it is necessary to perform processing after joining, processing stress remains in the balance wheel. Accordingly, there is a problem that the balance of the moment of inertia is liable to be deteriorated because it is easily deformed when a free end is formed on a part of the rim, and is likely to be deformed due to a change with time.

As described above, there has been a problem that the moment of inertia set at the time of design is largely deviated from the target value, and the rotational balance is lowered due to a temperature change. Therefore, it is necessary to adjust the moment of inertia of the balance with the balance and to adjust the amount of deformation with respect to the temperature of each rim. In addition, it is necessary to adjust the amount of screwing. For example, if a time delay occurs even if the temperature rises, a process of correcting the moment of inertia is performed by performing an operation such as moving the chiller screw to the free end side.
As described above, since a fine adjustment operation using a flicker screw is actually required, it takes time and effort to correct the temperature, and the workability is poor.

  The present invention has been made in view of such circumstances, and the purpose thereof is to perform temperature correction with high accuracy and simpleness, without the need to readjust the rate and without deteriorating the rotational balance and rotational performance. It is possible to provide a balance with a balance, a movement for a timepiece including the balance, a timepiece, and a method for producing the balance with a balance.

The present invention provides the following means in order to solve the above problems.
(1) A balance according to the present invention is rotatably supported by a balance stem, and is disposed around the balance, and one end is fixed to a connecting arm that is connected to the balance in the radial direction. A balance wheel having a fixed end portion and a balance wheel that is a free end portion that is deformable in the radial direction, wherein the balance wheel is radially inward and fixed to the connecting arm. A rim and a second rim made of a material having a coefficient of linear expansion different from that of the first rim, wherein the first rim and the second rim are mutually connected. It is characterized by being joined by a melted part obtained by melting the material.

  According to the balance with the present invention, when a temperature change occurs, there is a difference in the coefficient of thermal expansion between the first rim and the second rim, and the relative movement of the balance is restrained by the melted portion. The free end can be moved radially inward or outward. Thereby, the distance from the free end part of a balance wheel to a rotating shaft can be changed, and the moment of inertia of the balance with hairspring can be changed. Therefore, the inclination of the temperature characteristic of the moment of inertia can be changed, and the temperature dependence of the vibration cycle of the balance can be suppressed, so that a high-quality balance with less rate change due to temperature change can be obtained. Further, since the first rim and the second rim are joined by a melted portion obtained by melting each other material, the moment of inertia calculated in advance by the shape dimensions of the first rim and the second rim and the specific gravity of the material is changed. A balance wheel can be formed, reducing the moment of inertia and making it unnecessary to readjust the rate.

(2) In the balance with hair according to the present invention, the melted portion is characterized in that the first rim and the second rim are melted and joined by laser welding.
In this case, it is possible to obtain a high-quality balance with little influence of deformation or residual stress due to heat at the time of joining, and no change in moment of inertia or time-dependent change due to joining.

(3) In the balance with hair according to the present invention, the melted portion is formed continuously in a circumferential direction on a joint surface between the first rim and the second rim.
In this case, the separation and relative movement between the first rim and the second rim can be restricted to the maximum, and the amount of deformation of the free end due to temperature can be maximized.

(4) In the balance with hair according to the present invention, the melted portion is formed at an end portion of the joint surface by laser welding from a direction parallel to the joint surface between the first rim and the second rim. It is characterized by being.
In this case, the boundary between the first rim and the second rim to be joined is easy to visually recognize, and there is no deterioration in the joining quality due to the laser irradiation position shift, so that the temperature of the inertia moment can be corrected with high reliability.

(5) In the balance with hair according to the present invention, the melted portion is formed on the joint surface by laser welding from a direction substantially perpendicular to the joint surface between the first rim and the second rim. It is characterized by that.
In this case, the balance wheel can be formed with the minimum number of joints, and the balance with high quality can be easily obtained.

(6) A timepiece movement according to the present invention includes a barrel wheel having a power source, a train wheel that transmits a rotational force of the barrel wheel, and an escapement speed control mechanism that controls rotation of the train wheel. The speed control mechanism includes the balance according to the present invention.
According to the timepiece movement according to the present invention, as described above, the temperature dependency of the vibration period is suppressed, and the rate is difficult to change due to the temperature change. It can be.

(7) A timepiece according to the present invention includes the timepiece movement according to the present invention.
According to the timepiece of the present invention, the timepiece movement in which the rate is difficult to change due to a temperature change is provided, so that a high-quality timepiece with few errors can be obtained.

(8) A method for manufacturing a balance according to the present invention includes an individual rim shape processing step of processing the shapes of the inner diameter side and the outer diameter side of the first rim, and the shapes of the inner diameter side and the outer diameter side of the second rim, One outer diameter side and the other inner diameter side of the first rim and the second rim are brought into contact with each other to form a joining surface, and a melted portion in which the materials of the first rim and the second rim are melted is formed on the joining surface. And a joining step.
According to the balance producing method according to the present invention, it is possible to suppress the unexpected deformation of the free end after joining both rims. Further, it is possible to effectively reduce the residual stress generated during cooling after both rim joints.

  According to the present invention, it is not necessary to readjust the rate in the balance with temperature correction using the linear expansion coefficient difference, and the temperature correction operation can be performed easily and accurately without deteriorating the rotation balance and the rotation performance. It can be performed.

It is a figure which shows 1st Embodiment which concerns on this invention, Comprising: It is a block diagram of the movement of a mechanical timepiece. It is a top view of the balance with the movement shown in FIG. It is AA sectional drawing shown in FIG. It is a figure which shows the state which the balance with the balance shown in FIG. 2 deform | transformed. It is a figure which shows the other example of joining of the balance with hairspring shown in FIG. It is a figure which shows the other example of joining of the balance with hairspring shown in FIG.

Hereinafter, embodiments according to the present invention will be described with reference to the drawings.
As shown in FIG. 1, the mechanical timepiece 1 of the present embodiment is, for example, a wristwatch, and includes a movement (timepiece movement) 10 and a casing (not shown) that houses the movement 10.

(Composition of movement)
This movement 10 has a base plate 11 constituting a substrate. A dial (not shown) is arranged on the back side of the main plate 11. A train wheel incorporated on the front side of the movement 10 is referred to as a front train wheel, and a train wheel incorporated on the back side of the movement 10 is referred to as a back train wheel.

  A winding stem guide hole 11a is formed in the base plate 11, and a winding stem 12 is rotatably incorporated therein. The winding stem 12 is positioned in the axial direction by a switching device having a setting lever 13, a yoke 14, a yoke spring 15 and a back presser 16. In addition, a chichi wheel 17 is rotatably provided on the guide shaft portion of the winding stem 12.

  Under such a configuration, the winding stem 12 is rotated in a state where the winding stem 12 is in the first winding stem position (0th stage) closest to the inside of the movement 10 along the rotation axis direction. Then, the hour wheel 17 rotates through the rotation of the spell wheel (not shown). And when this chi-wheel 17 rotates, the round hole wheel 20 which meshes with this rotates. And when this round hole wheel 20 rotates, the square wheel 21 which meshes with this rotates. Further, when the square hole wheel 21 rotates, the mainspring (power source) (not shown) housed in the barrel complete 22 is wound up.

The front wheel train of the movement 10 includes a second wheel 25, a third wheel 26 and a fourth wheel 27 in addition to the barrel wheel 22, and functions to transmit the rotational force of the barrel wheel 22. Further, an escapement mechanism 30 and a speed adjusting mechanism 31 for controlling the rotation of the front wheel train are arranged on the front side of the movement 10.
The center wheel 25 is a gear that meshes with the barrel complete 22. The third wheel 26 is a gear that meshes with the second wheel 25. The fourth wheel 27 is a gear that meshes with the third wheel 26.

The escapement mechanism 30 is a mechanism for controlling the rotation of the above-described front wheel train, and an escape wheel 35 that meshes with the fourth wheel 27 and an ankle 36 that causes the escape wheel 35 to escape and rotate regularly. And.
The speed regulating mechanism 31 is a mechanism for regulating the escapement mechanism 30, and includes a balance 40 as shown in FIGS. 1 to 3.

(Structure of balance)
The balance with hairspring 40 constituting the speed regulating mechanism 31 includes a balance stem 41 that is rotatably supported around the rotation axis O and a balance wheel 42 fixed to the balance stem 41, and transmits from the escapement mechanism 30. By the potential energy stored in the hairspring 43 by the generated power, the member is rotated forward and backward around the rotation axis O with a constant vibration cycle.
In the present embodiment, a direction orthogonal to the rotation axis O is referred to as a radial direction, and a direction around the rotation axis O is referred to as a circumferential direction.

  The balance stem 41 is a rotating shaft body extending vertically along the rotating shaft O, and the upper end portion and the lower end portion thereof are pivotally supported by members such as a base plate and a balance holder not shown. A substantially intermediate portion in the vertical direction of the balance stem 41 is a large diameter portion 41a having the largest diameter. The balance wheel 42 is fixed to the balance stem 41 through the large diameter portion 41a.

In addition, a cylindrical swing seat 45 is externally mounted on the balance stem 41 coaxially with the rotation axis O at a portion located below the large diameter portion 41a. The swing seat 45 has an annular flange 45a projecting outward in the radial direction, and a swing stone 46 for swinging the ankle 36 is fixed to the flange 45a. .

  The hairspring 43 is, for example, a flat whiskers wound spirally in one plane, and the inner end of the hairspring 43 is fixed to a portion located above the large-diameter portion 41a of the balance stem 41 via a whisker ball 44. Has been. The hairspring 43 plays a role of accumulating the power transmitted from the fourth gear 27 to the escape wheel 35 and vibrating the balance wheel 42.

  As shown in FIGS. 2 and 3, the balance wheel 42 includes a substantially annular rim 50 that surrounds the balance stem 41 from the outside in the radial direction, and a connecting arm 51 that connects the rim 50 and the balance stem 41 in the radial direction. And.

  The rim 50 is a strip-like piece extending in the shape of an arc of 1/3 along the circumferential direction, and is uniformly arranged around the rotation axis O in a rotationally symmetrical manner. The rim 50 includes a first rim 54 disposed on the radially inner side and a second rim 55 disposed on the radially outer side along the first rim 54.

  The connecting arms 51 are arranged around the rotation axis O with an interval of 120 degrees. The base end side of the connecting arm 51 is connected to the large-diameter portion 41a of the balance stem 41, and the tip end side extends radially outward toward the rim 50 described above.

The first rim 54 and the distal end side of the connecting arm 51 are connected at the fixed end 50 a of the rim 50. Thereby, the rim 50 is supported by the balance stem 41 via the connecting arm 51.
The other end side in the circumferential direction of the rim 50 is a free end portion 50b that can be deformed in the radial direction, and a weight 52 is attached to the distal end side of the free end portion 50b.

The weight 52 is attached in order to increase the amount of change of the inertia moment due to the temperature change, and the temperature may not be corrected only by the amount of change of the inertia moment due to the deformation of the free end 50b. .
The first rim 54 and the second rim 55 of the rim 50 are restrained from relative movement in the vicinity of the melting portion 53 by a plurality of melting portions 53 spaced apart from each other by a predetermined distance.

The melted portion 53 is formed in a direction parallel to the boundary surface between the first rim 54 and the second rim 55, that is, on the upper and lower surfaces of the rim 50 by, for example, laser welding, and the first rim 54 and the second rim 55 are formed. Relative separation and sliding movement are constrained.
As a method for forming the melted portion 53, there is a fusion welding method that does not add a filler material such as resistance welding or electron beam welding in addition to laser welding.
The first rim 54 is made of a material having a linear expansion coefficient different from that of the second rim 55.

  In the present embodiment, the first rim 54 is described as being formed of a low thermal expansion material such as invar, and the second rim 55 is described as being formed of a higher thermal expansion material than the first rim 54 such as stainless steel. Therefore, when the ambient temperature rises, the second rim 55 expands more in the circumferential direction than the first rim 54, as shown in FIG. As a result, the free end 50b of the rim 50 moves radially inward. Along with this, the weight 52 attached to the tip of the free end 50b also moves radially inward (dotted line in FIG. 4).

In addition, the hairspring 43 of this embodiment is demonstrated as what consists of a general steel material which has a negative temperature coefficient from which a Young's modulus falls with a temperature rise.
Further, the materials of the first rim 54 and the second rim 55 are not limited to the above materials, and various materials may be appropriately selected and used. At this time, it is preferable to select both materials so that the difference in coefficient of thermal expansion is as large as possible.

Next, the procedure for forming the balance wheel in this embodiment will be described.
First, an annular first rim 54 including a connecting arm 51 made of a low expansion material and an annular second rim 55 made of a high expansion material are produced. Here, the outer diameter and inner diameter of the first rim 54 and the second rim 55 are each processed in the same process (individual rim shape processing process). Next, after the first rim 54 and the second rim 55 are combined, the melting portion 53 is formed at the boundary portion, and the first rim 54 and the second rim 55 are joined (joining step). Further, one end of the rim 50 is cut away to form a free end 50b.
In addition, after processing the first rim 54 and the second rim 55, it is preferable to perform a heat treatment for removing residual stress suitable for each material as necessary.

  As described above, after the processing of the outer shape such as the inner diameter side and the outer diameter side of the first rim 54 and the second rim 55 is completed, the first rim 54 and the second rim 55 are joined by the melting portion 53. Therefore, since it is possible to secure a degree of freedom in which the internal residual stresses of the first rim 54 and the second rim 55 can be adjusted (for example, by the above-described heat treatment) before joining, the free end is unexpectedly deformed after joining both rims. Can be suppressed. Moreover, since the joining of both rims is only local heating accompanying the formation of the melted portion 53, the residual stress generated during cooling can be effectively reduced. Therefore, the deformation of the free end and the deformation over time after the formation of the bimetal balance are suppressed, and the balance of the balance wheel can be stably secured.

(Inertia moment temperature correction method)
Next, a method for correcting the temperature of the moment of inertia using the balance 40 will be described.
According to the balance with hairspring 40 of the present embodiment, when a temperature change occurs, the second rim 55 expands and contracts more than the first rim 54, thereby moving the free end portion in the radial direction. That is, as shown in FIG. 4, when the temperature rises, the free end 50b can be moved inward in the radial direction by the expansion of the second rim 55. Can be moved outward in the radial direction.

  Therefore, by moving the position of the weight 52 attached to the tip of the free end 50b inward or outward in the radial direction, the distance from the rotation axis O to the weight 52 is changed to change the moment of inertia of the balance 40 itself. Can be made. That is, when the temperature rises, the position of the weight 52 can be moved radially inward to reduce the moment of inertia, and when the temperature drops, the weight 52 can be moved radially outward to move the inertia. The moment can be increased. As a result, the gradient of the temperature characteristic of the moment of inertia can be changed to a negative gradient, and therefore the temperature of the moment of inertia can be corrected.

  By the way, according to the balance with hairspring 40 of this embodiment, the first rim 54 and the second rim 55 are configured to have a dimensional shape calculated so as to have a predetermined moment of inertia in accordance with the spring constant of the hairspring 43 before joining. Since the melting part 53 melts and joins the materials of the first rim 54 and the second rim 55, it is different from joining using a brazing material as in the prior art, and the increase / decrease in weight due to joining. There is no. That is, even if the first rim and the second rim are joined by the melting portion 53, the inertia moment of the balance wheel 42 does not change, and a predetermined inertia moment calculated in advance can be obtained. Further, unlike the conventional method, since machining is not performed after joining, the ratio of the plate thickness of the first rim 54 and the second rim 55 does not change, and the amount of deformation with respect to temperature changes in the plurality of rims 50 does not change. There is no variation. Accordingly, since the plurality of rims 50 are uniformly deformed due to temperature changes, there is no reduction in rotational balance. Further, before joining the first rim 54 and the second rim 55, a heat treatment for removing residual stress can be appropriately performed, and local heating is performed at the time of joining, so that deformation occurs when the free end 50b is formed. It does not occur and does not change over time during use, so the moment of inertia balance does not deteriorate.

  Further, according to the balance with hairspring 40 of the present embodiment, the melted portion 53 has the first rim 54 and the second rim 55 melted and joined by laser welding. According to laser welding, since heating and melting can be performed locally, deformation due to heat in the peripheral portion and generation of residual stress due to bonding can be minimized. Therefore, there is no problem that the moment of inertia changes due to deformation at the time of joining or the shape changes with time due to the influence of residual stress and the accuracy of the vibration cycle is lowered.

(Join method by laser welding)
Next, a method for joining the first rim 54 and the second rim 55 by laser welding when the balance 40 is formed will be described.
As shown in FIGS. 2 to 3, the rim 50 has a first rim 54 arranged radially inside and a second rim 55 arranged radially outside, and the boundary is exposed on the upper surface and the lower surface in the rotation axis direction. Yes. Here, by irradiating the boundary from the upper surface and the lower surface in the rotation axis direction, a part of the first rim 54 and the second rim 55 is heated and melted to form a melted portion 53 and bonded. The balance wheel 42 is formed by forming the melting portion 53 at a predetermined interval. Here, the irradiation position of the laser can be positioned while observing with a camera, and the boundary between the first rim 54 and the second rim 55 can be accurately irradiated. Therefore, the first rim 54 and the second rim 55 can be reliably joined, and the balance with high reliability can be obtained.

  Further, as shown in FIG. 5, the melting portion 53 may be continuously formed in the circumferential direction without a gap. When laser is irradiated intermittently or continuously and the irradiation position is moved so that the melted portion 53 overlaps, it can be formed by so-called seam welding. In this case, the separation and relative movement between the first rim 54 and the second rim 55 can be restricted to the maximum, and the deformation amount of the free end 50b due to the temperature can be maximized.

  Moreover, as shown in FIG. 6, the fusion | melting part 53 may be formed in the joint surface by laser welding from the direction substantially perpendicular | vertical to the joint surface of the said 1st rim and the said 2nd rim. Here, by irradiating the laser from the circumferential side surface of the balance wheel 42, the melted portion 53 is formed on the joining surface and joined by lap welding in which the first rim 54 is also melted through the second rim 55. In this case, since the melting part 53 can restrain the 1st rim 54 and the 2nd rim 55 with the minimum number, a highly accurate balance can be obtained easily. Note that various combinations of the bonding forms shown in FIGS. 4, 5, and 6 are possible.

  In this embodiment, the hairspring 43 is made of a general steel material having a negative temperature coefficient in which the Young's modulus decreases with increasing temperature, the first rim 54 is formed of a low thermal expansion material, and the second rim 55 is Although it has been described that the first rim 54 is formed of a material having a higher thermal expansion than the first rim 54, a constant elastic material such as a coelin bar is used for the hairspring 43, the first rim 54 is formed of a high thermal expansion material, and the second rim 55. May be made of a material having a lower thermal expansion than the first rim 54. In this case, the free end 50b of the rim 50 can be deformed radially inward when the temperature rises, and radially outward when the temperature drops, and the moment of inertia that matches the balance spring 43 with a positive Young's modulus temperature coefficient. Temperature correction can be performed.

  As described above, according to the balance with hairspring 40 of the present embodiment, when the balance wheel 42 is formed, a highly accurate temperature correction is performed without changing the moment of inertia and without reducing the rotation balance due to the temperature change. Unlike the case of using a conventional flicker screw, there is no need to readjust the rate and the rotational balance.

In addition, according to the movement 10 of the present embodiment, the balance 40 with the above-described balance with which the temperature dependency of the vibration period is suppressed and the rate is difficult to change due to the temperature change is provided. be able to.
In addition, according to the mechanical timepiece 1 of the present embodiment, the above-described movement 10 in which the rate does not easily change due to a temperature change is provided, so that a high-quality timepiece with few errors can be obtained.

O ... Rotating shaft 1 ... Mechanical watch 10 ... Movement (watch movement)
22 ... barrel wheel 30 ... escape mechanism 40 ... balance 41 ... balance 42 ... balance wheel 43 ... balance spring 44 ... beard ball 50 ... rim 51 ... connecting arm 52 ... weight 53 ... melting part 54 ... first rim 55 ... first 2 rims

Claims (8)

A rotating stem that is rotatably supported, and a fixed end portion that is disposed around the spring and that has one end portion fixed to a connecting arm that is connected to the spring in the radial direction, and the other is a radial direction. A balance with a balance wheel that is a free end deformable to,
The balance wheel includes a first rim connected to the arm, and a second rim that is disposed to overlap the first rim and is formed of a material having a linear expansion coefficient different from that of the first rim. And
The balance with the said 1st rim and the said 2nd rim being joined by the fusion | melting part which fuse | melted the mutual material.   2. The balance according to claim 1, wherein the melted portion is obtained by melting and joining the first rim and the second rim by laser welding.   3. The balance according to claim 1, wherein the melted portion is continuously formed in a circumferential direction on a joint surface between the first rim and the second rim. 4.   The melted portion is formed at an end of the joint surface by laser welding from a direction parallel to the joint surface between the first rim and the second rim. The listed balance.   The said fusion | melting part is formed in the said joint surface by the said laser welding from the direction substantially perpendicular | vertical to the joint surface of the said 1st rim | limb and the said 2nd rim | limb. Tempu.   A barrel wheel having a power source, a wheel train that transmits the rotational force of the barrel wheel, and an escapement speed control mechanism that controls rotation of the wheel train, wherein the escapement speed control mechanism is claimed in claims 1 to 3. A watch movement equipped with one of the balances 5.   A timepiece having the timepiece movement according to claim 6. A method for producing a balance with the balance according to claim 1,
An individual rim shape processing step of processing the shapes of the inner diameter side and the outer diameter side of the first rim, and the shapes of the inner diameter side and the outer diameter side of the second rim;
One outer diameter side and the other inner diameter side of the first rim and the second rim are brought into contact with each other to form a joining surface, and the materials of the first rim and the second rim are melted on the joining surface. A joining step for forming the melted part,
A method for producing a balance with a balance.

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