CH706116B1 - Ferrule, sprung balance comprising such a ferrule and timepiece comprising such a sprung balance. - Google Patents

Abstract

The invention relates to a ferrule (50) for fixing an inner end (43) of a spring (40) to a balance shaft (30), comprising: a main body (51) defining an opening ( 53) coaxial with the balance shaft (30) and which can be threaded onto the balance shaft (30); and a support portion (55) projecting radially from an outer side of the main body (51) and supporting the hairspring (40), wherein a sealing surface (57), at which the inner end (43) of the hairspring (40) is welded, is formed by a lateral surface that the support portion has in the radial direction, and a reentrant (61,64) or a hole (66) is present in at least one end surface among two end surfaces (56a, 56b) that the support portion (55) has in an axial direction of the main body (51). The invention aims to prevent cracks in the main body of the shell when it is threaded by driving on a balance shaft. The invention also relates to a sprung balance comprising such a ferrule, and a timepiece comprising such a sprung balance.

Description

Description

BACKGROUND OF THE INVENTION

1. Field of the invention The present invention relates to a ferrule, a sprung balance including this ferrule, and a timepiece.

2. Description of the Prior Art [0002] A known mechanical timepiece includes an escapement and a regulating mechanism for controlling the rotation of a barrel wheel, a center mobile, a third mobile and a second mobile which form a front cog. An exhaust and regulating mechanism includes an exhaust mobile and a balance spring. The balance spring is formed by a balance wheel, a balance axle which is a center of rotation of the balance wheel, a balance spring which causes the balance wheel to rotate by expansion and contraction, and a ferrule which fixes the balance spring to the pendulum axis. In general, the ferrule is an element which has an approximately annular shape and which includes a main body threaded on the pendulum axis, and a welding surface to which the inner side end of the hairspring is welded on the outside in the radial direction of the main body.

For example, the ferrule (corresponding to a "ferrule" in the claims of this application) disclosed in JP-A-2005-300 532 (Patent document 1) is formed of a strip (corresponding to the "body main "in the claims of this application) made of metal, and an opening for incorporating the ferrule into a pendulum axis (corresponding to a" pendulum axis "in the claims of this application) is formed in the internal contour. Furthermore, in the external contour, the action point (corresponding to a “welding surface” in the claims of the present application) between the ferrule and a balance spring (corresponding to a “hairspring” in the claims of the present application) is arranged at the end of an arm, at a position where the distance R from the center O of the pendulum axis is greater than at any other point of the external contour.

The end (corresponding to an “inner side end” in the claims of the present application) of the internal curve of the balance spring is welded to the point of action of the ferrule, and thus, the balance spring is attached to the ferrule. Furthermore, the balance axle is inserted into the opening of the strip by driving out, and thus, the ferrule to which the balance spring is fixed is assembled to the balance axis. In other words, the balance spring is assembled to the balance axle by the ferrule.

[0005] However, there are the following problems in the shell of the prior art.

When the inside end of the hairspring is welded to the welding surface of the ferrule, the heat at the time of welding is transferred to the main body of the ferrule, from the welding surface of the ferrule.

At this time, in particular, in the main body of the shell, the outermost part in the radial direction and close to the welding surface reaches a high temperature and is annealed, and the hardness is reduced. On the other hand, since in the main body of the shell, the innermost part in the radial direction and distant from the welding surface is not annealed, the hardness is not changed. However, the hardness of the innermost part is relatively higher than the hardness of the outermost part in the radial direction which is annealed. Therefore, compared to the main body of the ferrule before the hairspring is welded, in the main body of the ferrule after the hairspring has been welded, the part having a relatively high hardness (i.e. the part where there was no annealing) was reduced in the radial direction. In this way, when the pendulum axis is inserted into the opening of the shell by driving out, cracks appear in the reduced part having a high hardness in the main body of the shell, and it is feared that manufacturing defects appear.

In addition, in recent years, to make the shell having a special shape at a low cost, a technique using electroforming is used. In general, when the shell is made using electroforming, nickel and the nickel alloy are adopted as the shell material. Here, since the melting point of nickel and the nickel alloy is higher than a metal such as steel, the welding temperature when the hairspring is welded to the shell is high. In this way, in the main body of the shell, the outermost part in the radial direction and close to the welding surface is more easily annealed. Therefore, since in the main body of the ferrule, the innermost part in the radial direction and having a relatively high hardness is considerably reduced in the radial direction, the problems described above become particularly noteworthy.

SUMMARY OF THE INVENTION Consequently, an object of the present invention is to propose a ferrule capable of preventing cracks in the main body when the ferrule is threaded by driving on the pendulum axis, a pendulum- hairspring including this ferrule, and a timepiece.

To achieve this object, a ferrule of the present invention is a ferrule for fixing an inner side end of a hairspring to a pendulum axis, comprising:

a main body which delimits an opening coaxial with the pendulum axis and which can be threaded on the pendulum axis; and a support part which projects in a radial direction, from an external side of the main body, and which supports the hairspring, in which a welding surface, to which the inner side end of the hairspring is welded, is formed by a lateral surface that the support part has in the radial direction, and a reentrant or a hole is present in at least one end surface among two end surfaces that the support part has in an axial direction of the main body.

According to the present invention, since the reentrant or the hole is provided on the support part, compared to the case where the reentrant or the hole is not present, the cross section of a heat propagation path by which the heat at the time of welding spreads can be reduced. Therefore, a coefficient of heat transfer from the support part to the main body from the welding surface can be decreased. Furthermore, the heat at the time of welding is transferred to the main body around the reentrant or hole from the welding surface. In this way, compared to the case where the re-entrant or the hole is not present, since the heat transfer path from the welding surface to the main body is longer, the heat transfer coefficient of the part of support can be decreased. In addition, compared to the case where no reentrant or no hole is present, since the surface area is larger, the support part may well radiate heat due to the fact that the reentrant or the hole is formed.

In this way, since the heat at the time of welding is not easily transferred from the welding surface to the main body, an annealed region can be limited to the region extending from the welding surface to neighborhood of the reentry or hole. Therefore, since the part which is not annealed in the main body of the shell and which has a relatively high hardness can be thick for sure and it is possible to prevent the part having a relatively high hardness from being thin, cracks likely to appear in the main body when the ferrule is threaded by driving on the pendulum axis can be avoided.

In addition, in a ferrule according to an embodiment of the present invention, the reentrant is a recess where the end surface of the support part is recessed in the axial direction, from a body side region, main to the welding surface.

According to this embodiment of the present invention, since the reentrant is formed in the form of a recess, the reentrant can be simply formed using electroforming, machining, or the like.

Furthermore, in a ferrule according to an embodiment of the present invention, the reentrant is a groove which extends along a circumferential direction of the main body.

According to this embodiment of the present invention, since the reentrant is formed in the form of a groove, the reentrant can be simply formed using electroforming, machining, or the like.

In addition, in a ferrule according to an embodiment of the present invention, the hole is a through hole which communicates with the two end surfaces of the support part.

According to this embodiment of the present invention, since the through hole is formed on the support part, the cross section of the heat transfer path to which the heat at the time of welding is transferred can be further reduced, and the heat transfer coefficient of the support part can be further reduced. Furthermore, the heat at the time of welding is transferred to the main body, around the through hole, from the welding surface. In this way, when the heat at the time of welding is transferred from the welding surface to the main body, the linear heat propagation path which connects the welding surface and the main body is cut by the through hole. In other words, since the heat at the time of welding is transferred from the welding surface to the main body around the outer side in the radial direction of the through hole, the heat transfer coefficient of the support part can be further decreased . Therefore, since it is possible to further prevent the part having a relatively high hardness in the main body of the ferrule from being thin, cracks may appear in the main body when the ferrule is threaded on the pendulum axis can be well avoided.

Furthermore, since the hole can be formed in the form of a through hole and this through hole can be simultaneously formed in addition to the main body and the support part of the shell, using electroforming, the hole can be simply formed at a low cost.

Furthermore, in a ferrule according to an embodiment of the present invention, the recess is formed so that the relationship L1> L2 is satisfied, where L1 is the shortest distance between a flange of the recess and the opening and where L2 is the shortest distance between the edge of the recess and the welding surface.

According to this embodiment of the present invention, since it can be guaranteed that the shortest distance L1 between the edge of the recess and the opening can be greater than the shortest distance L2 between the edge of the recess and the welding surface, the region which is annealed due to the heat at the time of welding can be limited to the short distance from the welding surface in the vicinity of the flange. In addition, since a heat transfer coefficient can be reduced by guaranteeing a long path of heat propagation until the opening of the main body, from the rim, the heat which is not radiated from the rim of the recess n is not easily transferred from the recess edge to the main body. Therefore, since the part which is not annealed in the main body of the shell and which has a relatively high hardness can be thicker for sure and that it is possible to prevent more than the part having a relatively hardness high or thin, cracks likely to appear in the main body when the ferrule is threaded by driving on the pendulum axis can be well avoided.

Furthermore, in a shell according to an embodiment of the present invention, the reentrant or the hole is formed so that the relationship L3> L4 is satisfied, where L3 is the shortest distance between the reentrant or the hole and the opening and where L4 is the shortest distance between the re-entrant or the hole and the welding surface.

According to this embodiment of the present invention, since it can be guaranteed that the shortest distance L3 between the reentrant or the hole and the opening can be greater than the shortest distance L4 between the reentrant or the hole and the welding surface, the region which is annealed due to the heat at the time of welding can be limited to the short distance from the welding surface in the vicinity of the reentrant or the hole. In addition, since a heat transfer coefficient can be decreased by ensuring a long path of heat propagation until the opening of the main body, from the reentry or the hole, the heat which is not radiated from the reentrant or the hole is not easily transferred from the reentrant or the hole to the main body. Therefore, since the part which is not annealed in the main body of the shell and which has a relatively high hardness can be thicker for sure and that it is possible to prevent more than the part having a relatively hardness high or thin, cracks likely to appear in the main body when the ferrule is threaded by driving on the pendulum axis can be well avoided.

In addition, in a ferrule according to an embodiment of the present invention, there is provided a plurality of support parts in each of which a copy of the welding surface and a copy of the reentrant or hole are formed, the support parts being formed at regular intervals in the circumferential direction of the main body.

According to this embodiment of the present invention, since the plurality of support parts are formed in the circumferential direction at regular intervals, the center of gravity of the ferrule can be arranged at the center of rotation of the ferrule. In this way, when the ferrule rotates, the ferrule can rotate stably without vibration. Therefore, when a balance spring and a timepiece are formed having the ferrule of the present invention as a component, errors in the rotation period are decreased and improved performance can be guaranteed.

Furthermore, since several support parts on which the welding surfaces are formed are provided, when the hairspring is welded to the shell, no welding surface among the welding surfaces of the plurality of support parts and the inner side of the hairspring are positioned towards each other, and welding can be carried out. In this way, compared to a case where there is a welding surface of the support part, the positioning between the welding surface of the ferrule and the inside end of the hairspring can be carried out quickly. On the other hand, since the concave parts are formed in the support parts respectively, even when the inner side end of the hairspring is welded to the welding surface of any support part, annealing in the part close to the surface of welding of the main body can be omitted. Consequently, operating efficiency can be improved when the balance spring is welded to the shell, and cracks which may appear in the main body when the shell is threaded on the balance axle can be avoided.

Furthermore, in a ferrule according to an embodiment of the present invention, the ferrule is a ferrule produced by electroforming.

When the shell is formed by electroforming, in most cases, nickel and the nickel alloy are adopted as the material. Here, in general, since the melting points of nickel and the nickel alloy are high compared to a metal such as steel, the welding temperature when the hairspring is welded to the shell is high. However, according to the present invention, since the re-entrant or the hole is provided on the support part, the heat transfer coefficient of the support part can be decreased, and the heat can be well radiated from the support part. In this way, even when the welding temperature is high, it is possible to prevent the main body from being annealed. Therefore, the specially shaped ferrule can be formed at a low cost, and cracks which may appear in the main body when the ferrule is threaded on the balance pin by driving out can be avoided. In this way, the present invention is particularly suitable for a shell produced by electroforming.

Furthermore, a balance spring according to the present invention includes a ferrule as defined above.

In addition, a timepiece according to the present invention includes a balance spring as defined above.

According to the present invention, since cracks in the main body can be prevented when the ferrule is threaded by driving on the balance shaft, the balance spring and the timepiece can be made without manufacturing defects.

According to the present invention, since the reentrant or the hole is provided on the support part, compared to a case where the reentrant or the hole is not present, the cross section of a heat propagation path by which the heat at the time of welding is transferred can be reduced. Therefore, a heat transfer coefficient of the support part from the welding surface to the main body can be reduced. Furthermore, at the time of welding, the heat is transferred to the main body around the reentrant or hole, from the welding surface. In this way, compared to the case where the re-entrant or the hole is not present, since the heat transfer path from the welding surface to the main body is long, the heat transfer coefficient of the support part can be decreases. In addition, since the reentrant or the hole is present, compared to the case where the reentrant or the hole is not present, since a surface area is larger, the support part may well radiate heat.

In this way, since the heat at the time of welding is not easily transferred from the welding surface to the main body, an annealed region can be limited to the region going from the welding surface in the vicinity of the reentrant or the hole. Therefore, since the part which is not annealed in the main body of the shell and which has a relatively high hardness can be thick for sure and it is possible to prevent the part having a relatively high hardness from being thin, cracks likely to appear in the main body when the ferrule is threaded by driving on the pendulum axis can be avoided.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a plan view of a complete timepiece as viewed from the rear side.

Fig. 2 is a view of a movement as seen from the front side.

Fig. 3 is a plan view of a balance spring as seen in an axial direction.

Fig. 4 is a sectional view along line A-A of FIG. 3.

Fig. 5 is an explanatory view of a hairspring.

Fig. 6 is a plan view of a ferrule according to a first embodiment.

Fig. 7 is a sectional view along line B-B of FIG. 6.

Fig. 8 is an explanatory view on which the hairspring is welded to the shell.

Fig. 9 is a sectional view of a ferrule according to a first modification of the first embodiment.

Fig. 10 is a sectional view of a ferrule according to a second modification of the first embodiment.

Fig. 11 is a block diagram of a process for manufacturing the shell.

Fig. 12 is a view showing a state where an electroforming mold is immersed in an electroforming liquid.

Fig. 13 is a view showing a state where electroforming is carried out and a metal body grows in a hole to form an outline.

Fig. 14 is a plan view of a ferrule according to a second embodiment.

Fig. 15 is a sectional view along line C-C of FIG. 14.

Fig. 16 is a plan view of a ferrule according to a third embodiment.

Fig. 17 is a sectional view along line D-D of FIG. 16.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. In what follows, firstly, after a timepiece and a balance spring, a ferrule according to the first embodiment and the method of manufacturing the ferrule are described.

Timepiece In general, a mechanical assembly including a drive part of a timepiece is called the "movement". A state where a dial and a hand are mounted on the movement and inserted into a timepiece box to make a finished product is called the "complete timepiece". Among the two sides of a plate of the timepiece, the side on which a crystal of the timepiece box is placed, i.e. the side on which the dial is placed, is called the “rear side”, the “glass side” or the “dial side” of the movement. Among the two sides of the plate, the side on which the case back of the timepiece box is arranged, that is to say the side opposite the dial, is called the "front side" or the " case back side of the movement.

[0037] FIG. 1 is a plan view of a timepiece 1 which is a complete timepiece 1a.

As shown in FIG. 1, the complete timepiece 1a includes a dial 2 which has a scale 3 or the like indicating information with respect to time. In addition, the hands 4, which include an hour hand 4a indicating the hours, a minute hand 4b indicating the minutes, and a second hand 4c indicating the seconds, are provided.

[0039] FIG. 2 is a view of a movement 100 as seen from its front side. Furthermore, in FIG. 2, for an easy understanding of the drawing, part of the timepiece components forming the movement 100 is not shown.

The movement 100 of a mechanical timepiece includes a plate 102. A winding rod 110 is rotatably incorporated in a winding rod guide hole 102a of the plate 102. The axial position of the rod The winder 110 is determined by a switching device which includes an adjustment lever 190, a rocker 192, a rocker spring 194, and a jumper of the adjustment lever 196.

In addition, if the winding stem 110 is turned, a winding pinion 112 is rotated by a rotation of a sliding pinion (not shown). A crown wheel 114 and a pawl wheel 116 are rotated by rotation of the clutch pinion 112, and a motor spring (not shown) which is received in the barrel wheel 120 is wound.

The barrel wheel 120 is rotatably supported between the plate 102 and the barrel bridge 160. A center mobile 124, a third mobile 126, a second mobile 128, and an exhaust mobile 130 are supported in a rotary manner between the plate 102 and a gear train 162.

If the barrel wheel 120 is rotated by a force produced by the mainspring, the center mobile 124, the third mobile 126, the second mobile 128 and the exhaust mobile 130 are rotated by the rotation of the barrel wheel 120. The barrel wheel 120, the center mobile 124, the third mobile 126 and the second mobile 128 form a front wheel train.

If the center mobile 124 is rotated, a pinion (not shown) is rotated simultaneously on the basis of the rotation, and a minute hand 4b (refer to fig. 1) which is mounted on this pinion indicates minutes". Furthermore, an hour wheel (not shown) is rotated by the rotation of a minute wheel (not shown) on the basis of the rotation of the pinion carrying the minute hand 4b, and an hour hand 4a (se refer to fig. 1) which is mounted on the hour wheel indicates the "hours".

An exhaust-regulator device assembly for controlling the rotation of the front wheel drive consists of an exhaust mobile 130, an anchor 142, and a balance spring 10.

A toothing 130a is formed on the outer circumference of the exhaust mobile 130. The anchor 142 is rotatably supported between the plate 102 and the anchor bridge 164 and comprises a pair of pallets 142a and 142b. The exhaust mobile 130 is temporarily stopped in a state where a pallet 142a of the anchor 142 is engaged in the teeth 130a of the exhaust mobile 130.

The balance spring 10 rotates back and forth with a fixed period, and therefore, the teeth 130a of the exhaust mobile 130 is alternately engaged or released with the pallet 142a and the other pallet 142b of the anchor 142. In this way, the exhaust mobile 130 escapes at a constant speed.

Below, the configuration of the balance spring 10 will be described in detail.

Spiral balance [0049] FIG. 3 is a plan view when the balance spring 10 is seen in an axial direction, from the rear side of the movement 100 (refer to FIG. 2). In addition, in fig. 3, a peak 106 is shown in phantom with two dashes.

[0050] FIG. 4 is a sectional view along line A-A of FIG. 3. In addition, the plate 102, a balance bridge 104, and the stud 106 are shown in phantom with two dashes.

As shown in FIG. 3, the balance spring 10 mainly comprises a balance wheel 20, a balance axle 30, a spring 40 and a ferrule 50.

Balance wheel [0052] For example, the balance wheel 20 is made of a metal such as brass and includes a main body of the balance wheel 21 which is formed in an approximately annular shape. The central axis of the main balance wheel body 21 coincides with the central axis O which is the axis of rotation of the balance spring 10.

Four arms 23 (23a to 23d) extend in the radial direction in the direction of the central axis O from an internal circumferential surface 21a of the main body of the balance wheel 21. The four arms 23a to 23d are formed at approximately equal intervals to have an angle of 90 ° in the circumferential direction of the balance wheel main body 21. The four arms 23a to 23d gradually widen from the inner circumferential surface 21a of the balance wheel main body 21, direction of the central axis O, and are connected in the vicinity of the central axis O.

As shown in FIG. 4, an insertion hole 25a which is coaxial with the central axis O is formed in the connection part 25 of the four arms 23a to 23d. The pendulum pin 30 is inserted by driving into the insertion hole 25a of the connection part 25.

Balance axis 10 The balance spring 10 comprises the balance axis 30 mounted coaxially with the central axis O. For example, the balance axis 30 is an element formed of a bar which is made of a metal such as brass.

The pendulum axis 30 includes a pin 31 (31a and 31b) which is formed to be pointed at the ends in the axial direction. A lug 31a is pivotally assembled to the balance bridge 104 by a bearing (not shown), the other lug 31b is pivotally assembled to the plate 102 by a bearing (not shown), and therefore, the axis balance 30 can rotate around the central axis O.

The insertion hole 25a of the connection part 25 of the balance wheel 20 is driven in the approximate center, in the axial direction, on the balance axis 30. In this way, the balance wheel 20 and the pendulum axis 30 are assembled.

The pendulum axis 30 includes a double plate 35 which has an approximately cylindrical shape. A ferrule-shaped portion 36 which extends in the radial direction is formed in the double plate 35. A pulse pin (not shown) is provided in a predetermined position outside, in the radial direction, of the part in the shape of a ferrule 36. The impulse pin alternately returns the pallet 142a and the other pallet 142b of the anchor 142 in synchronization with the period of the reciprocating rotation of the balance-spring 10. From this manner, the pallet 142a and the other pallet 142b of the anchor 142 are engaged in the toothing 130a of the exhaust mobile 130 and released from this toothing 130a.

Spiral As shown in FIG. 4, the balance spring 10 comprises the spring 40.

[0060] FIG. 5 is an explanatory view of the hairspring 40. Furthermore, in FIG. 5, the hairspring 40 is shown in a polar coordinate system. In addition, an Archimedes X curve, the pendulum axis 30, and the ferrule 50 described below are shown in phantom with two dashes.

As shown in FIG. 5, for example, the hairspring 40 is a flat spring which is made of a metal such as steel or nickel, and is formed by a main hairspring body 41 having a plurality of windings and by an arcuate part 42 outer side of main hairspring 41.

The main hairspring body 41 is formed so as to extend along a curve called the Archimedes X curve.

An Archimedes X curve is a curve whose polar equation, in the polar coordinate system, is as follows:

r = a0 (a is constant) (1) The main body of hairspring 41 is formed so as to extend along the curve of Archimedes X, and therefore, the main body of hairspring 41 is configured to so as to be a spiral and to be adjacent at approximately equal intervals in the radial direction, when viewed in the axial direction.

As shown in FIG. 3, the outer side of the main hairspring body 41 is provided with the arcuate part 42 which is formed to have a radius of curvature wider than that of the main hairspring body 41. The end 42a of the arched part 42 is fixed to the piton 106 which is constructed by a piton support (not shown) from the balance bridge 104 (refer to fig. 4). Furthermore, the interior side end 43 of the hairspring 40 is fixed to the ferrule 50.

Ferrule according to the first embodiment [0066] FIG. 6 is a plan view of the shell 50 according to a first embodiment when it is seen in the axial direction. In addition, in fig. 6, the pendulum axis 30 and the hairspring 40 are shown in phantom with two dashes.

[0067] FIG. 7 is a sectional view along line B-B of FIG. 6. In addition, in Figs. 6 and 7, the boundary between a main body 51 and a support part 55 is represented by a dotted line.

As shown in FIG. 6, for example, the ferrule 50 is an annular element which is made of nickel, nickel alloy, or the like, and comprises the main body 51 which is threaded on the pendulum axis 30, and the support part 55 which is formed so as to project outwards in the radial direction of the main body 51. As shown in FIG. 7, the thickness, in the axial direction, of the main body 51 of the ferrule 50 is chosen so as to be sufficiently thicker than the thickness, in the axial direction, of the hairspring 40 (that is to say, the width of the hairspring 40).

Main body As shown in FIG. 6, the outline of the main body 51 is shaped with an approximately elliptical annular shape, and has a large axis in a first direction F (direction to go from left to right in FIG. 6) in the radial direction and a small axis in a second direction S (direction going from top to bottom in fig. 6) perpendicular to the first direction F.

The main body 51 has a predetermined thickness in the radial direction, and an opening 53 is provided in the center of the main body. The opening 53 is shaped with an approximately elliptical shape which has a major axis in the first direction F and a minor axis in the second direction S to correspond to the outline of the main body 51. Due to the opening 53, the main body 51 is shaped so as to be threaded on the balance pin 30.

The main body 51 includes a pair of expanded parts 51a and 51a where the two sides are expanded outward in the radial direction. Furthermore, the main body 51 comprises a pair of parts 51b and 51b where the diameter of the internal circumferential surface is chosen so as to be smaller than the external diameter of the pendulum axis 30. The expanded parts 51 a and 51 a are provided, and therefore, when the pendulum axis 30 passes through the opening 53, a space is formed between the external circumferential surface of the pendulum axis 30 and the expanded parts 51a and 51a. In this way, when the main body 51 is threaded by driving on the balance pin 30, the expanded parts 51 a and 51 a can be easily elastically deformed. Consequently, due to the elastic force of the expanded parts 51 a and 51 a, there is no more deterioration when the parts 51 b and 51 b of the ferrule 50 are threaded by driving out and an appropriate holding force with respect to the pendulum axis 30 can be guaranteed.

Support part [0072] A pair of support parts 55 and 55 is formed on the outer side, in the radial direction, of parts 51b and 51b of the main body 51. The support parts 55 are formed to project outwards , in the radial direction, from the parts 51b of the main body 51. The support part 55 is shaped with a point shape in which the width in the first direction F gradually decreases from the internal side in the radial direction, towards the outside in the radial direction.

The two support parts 55 and 55 are formed on both sides in the radial direction, by interposing the central axis O, and are formed at regular intervals (an angle of 180 ° in the present embodiment) in the circumferential direction of the main body 51. Furthermore, the recesses 61 described below are formed in the pair of support parts 55 and 55 respectively. The effects when the recesses 61 are formed in the pair of support portions 55 and 55 respectively will be described below.

Welding surfaces 57 are formed on the lateral surface, on the external side in the radial direction, of the pair of support parts 55 and 55 respectively. For example, the inner circumferential surface 43a of the inner side end 43 of the main hairspring body 41 of the hairspring 40 is welded to the welding surfaces 57 using laser welding. A weld core 71, which is formed when laser welding is performed, is formed so as to intersect the weld surface 57, in the end surface in the axial direction, of the support portion 55 and the hairspring 40 .

For example, the welding surface 57 is conformed to the shape of a curved surface which has a curvature corresponding to the Archimedes curve X (refer to FIG. 5) to be along the circumferential surface internal 43a of the inner side end 43 of the hairspring 40.

A pair of welding surfaces 57 is formed on both sides in the radial direction, by interposing the central axis O, corresponding to the pair of support parts 55 and 55. Consequently, when the hairspring 40 is welded at the ferrule 50, the welding surface 57 of a support part 55 and the interior side end 43 of the hairspring 40 are positioned towards one another and the welding can be carried out. Therefore, compared to a case where there is a welding surface 57 of the support part 55, the positioning between the welding surface 57 of the shell 50 and the interior side end 43 of the hairspring 40 can be carried out quickly. In this way, the efficiency of the operation in which the hairspring 40 is welded to the shell 50 can be improved. Furthermore, the welding of the ferrule 50 and the hairspring 40 will be described below.

Incidentally, errors affecting the period of rotation of the balance spring 10 depend on the precision of the position at which the balance spring 40 is fixed. Specifically, as shown in fig. 5, when looking in the axial direction, since the central axis of the Archimedes curve X corresponding to the main balance spring 41 and the central axis O of the balance spring 10 coincide with each other, the smallest positional offset between the two (hereinafter called "horizontal deviation"), the smallest errors in the period of rotation of the balance spring 10.

In addition, when viewed from the external side in the radial direction, the smaller the angular offset (hereinafter called "vertical deviation") between the central axis of the Archimedes curve X corresponding to the body main balance spring 41 and central axis O of balance spring 10, plus the errors affecting the period of rotation of balance spring 10 are minimal.

Here, since the welding surface 57 is conformed to the shape of a curved surface which has a curvature corresponding to the Archimedes curve X, when the inner side end 43 of the hairspring 40 is welded to the surface of welding 57, the welding surface 57 of the support part 55 and the internal circumferential surface 43a of the hairspring 40 can come into surface contact with each other. In this way, since the positional offset between the welding surface 57 and the hairspring 40 is eliminated and the welding can be carried out stably in a state where the horizontal deflection and the vertical deflection of the hairspring 40 are reduced, the balance spring 10 with which errors affecting the rotation period are decreased can be realized.

As shown in FIG. 7, the recess 61 is formed as a reentrant 60 in an end surface 56a on the plate side 102 from the side (refer to FIG. 4 and the right side in FIG. 7) of two end surfaces 56a and 56b of the support part 55 in the axial direction. The recess 61 is formed by making an end surface 56a of the support part 55 concave in the axial direction. In this way, a flange 62 which is turned outwards in the radial direction is formed in the support part 55.

For example, the depth, in the axial direction, of the recess 61 is chosen so as to be approximately half the thickness, in the axial direction, of the main body 51. Since the recess 61 is provided, an area 55a, where the recess is present and which is positioned more outside in the radial direction than the flange 62 in the support part 55, is thinner, in the axial direction, than an area 55b where the recess does not is not present and is positioned further inside, in the radial direction, than the flange 62.

In addition, it is preferable that the thickness, in the axial direction, of the area 55a (that is to say the width, in the axial direction, of the welding surface 57) is greater than the thickness, in the axial direction, of the hairspring 40 (that is to say the width of the hairspring 40). In this way, the internal circumferential surface 43a of the hairspring 40 comes into contact with the welding surface 57 without projecting in the axial direction, from the welding surface 57, and can be welded. Consequently, the welding surface 57 and the hairspring 40 can be welded firmly to each other while the positional offset between the welding surface 57 and the hairspring 40 is eliminated. Moreover, it is preferable that the width, in the axial direction, of the welding surface 57 is less than 1.2 times the width of the hairspring 40.

Here, the shortest distance between the flange 62 of the recess 61 and the internal circumferential surface 53a of the opening 53 is denoted L1, and the shortest distance between the flange 62 of the recess 61 and the welding surface 57 is noted L2. The recess 61 is formed so that the following equation (2) is satisfied:

L1> L2 (2) In other words, the recess 61 is formed so that Equation (2) is satisfied, and therefore, the shortest distance L1 between the edge 62 of the recess 61 and the opening 53 is larger than the shortest distance L2 between the flange 62 of the recess 61 and the welding surface 57. In this way, as described below, when the inner side end 43 of the hairspring 40 is welded to the surface welding 57 of the shell 50, the region which is annealed due to the heat at the time of welding can be limited to the short distance from the welding surface 57 in the vicinity of the flange 62.

In addition, since a heat transfer coefficient can be reduced by guaranteeing a long path of propagation of heat to the main body 51 from the rim 62, the heat which is not radiated from the rim 62 of the recess 61 is not easily transferred from the edge 62 of the recess 61 to the main body 51. Consequently, since the part which is not annealed in the main body 51 of the shell 50 and which has a relatively high hardness may be more thick for sure and it is possible to prevent more that the part having a relatively high hardness is thin, cracks likely to appear in the main body 51 when the ferrule 50 is threaded by driving on the pendulum axis 30 can be well avoided.

Furthermore, the recesses 61 are shaped so as to have the same shape respectively in the two support parts 55 and 55 formed at regular intervals in the circumferential direction. In this way, since the weight of each of the support parts 55 and 55 is approximately the same, the center of gravity of the ferrule 50 is disposed at the center of rotation of the ferrule 50 (i.e. the central axis O). Therefore, since the ferrule 50 can rotate stably without vibration, errors affecting the rotation period are reduced and improved performance is guaranteed when the balance spring 10 (refer to Fig. 3) and the workpiece timepieces 1 (refer to fig. 1) are formed by having the ferrule 50 of the present embodiment as a component.

Furthermore, since the recesses 61 are formed in the pair of support parts 55 and 55 respectively, even when the interior side end 43 of the hairspring 40 is welded to the welding surface 57 of any support part 55, annealing in the part close to the welding surface 57 of the main body 51 can be eliminated. Consequently, the efficiency of the operation can be improved when the hairspring 40 is welded to the ferrule 50, and cracks which may appear in the main body when the ferrule 50 is threaded by driving on the pendulum axis 30. can be avoided.

Welding of the ferrule and the hairspring FIG. 8 is a schematic explanatory view on which the hairspring 40 is welded to the shell 50.

As shown in FIG. 8, for example, the inner side end 43 of the hairspring 40 is welded to the welding surface 57 of the shell 50 described above using laser welding. As a specific welding technique, firstly, an end surface 56b, in the axial direction, of the support part 55 and an end surface 41b, in the axial direction, of the main hairspring body 41 adjoins an adjustment tool. of position such as a flat plate 86, and the other end surface 56b of the support part 55 and the other end surface 41b of the main hairspring body 41 are placed approximately level one with the 'other.

Then, using a laser welder 85 having a predetermined output laser and a predetermined irradiation category, a laser 88 having a predetermined output is directed onto an area in the vicinity of the welding surface 57 of the ferrule 50, from the side where the recess 61 is formed, and laser welding is performed. In this way, as shown in fig. 6, the weld core 71 is formed so as to intersect the weld surface 57, in a single end surface 56a of the support part 55 and a single end surface 41a of the main hairspring body 41, and the hairspring 40 is welded to the ferrule 50.

Here, since the part 61 is formed in the support part 55 between the welding surface 57 and the main body 51, the area 55a of the support part 55, where the offset is present, is thinner, in the axial direction, that the zone 55b where the offset is not present. In this way, the cross section perpendicular to the second direction S, that is to say the cross section of the heat propagation path by which the heat is propagated at the time of welding, is reduced compared to the case where the recess 61 is not expected, and the heat transfer coefficient is decreased. In addition, compared to the case where the recess 61 is not provided, since the surface area of the support part 55 is increased by forming the recess 61, the heat at the time of welding is well radiated. In this way, since the transfer of heat at the time of welding to the main body 51 is suppressed due to the recess 61, the annealing region is limited to the region extending from the welding surface 57 to the vicinity of the recess 61. Consequently, the part which is not annealed in the main body 51 of the shell 50 and which has a relatively high hardness can certainly be thick, and it is possible to prevent the part having a relatively hardness high be thinned.

Furthermore, at this time, as shown in FIG. 6, it is preferable that the diameter of the weld core 71 formed by laser welding is formed so as to have approximately the same width, in the direction along the circumferential direction, as the weld surface 57. In this way, when looking in the axial direction, since the outer edge of the weld core 71 is formed so as to reach the two ends, in the circumferential direction, of the weld surface 57, the weld surface 57 can be welded to the surface circumferential 43a of the hairspring 40 on the assembly, along the circumferential direction, of the welding surface 57. Therefore, the hairspring 40 can be welded firmly to the welding surface 57 of the support portion 55. Furthermore , since the width, in the circumferential direction, of the welding surface 57 and the diameter of the welding core 71 are approximately equal, it is possible to prevent the welding of the welding surface 57 and the hairspring 40 to be dispersed. In this way, since a dispersion along the length of the hairspring 40, which can widen and contract, can be eliminated, the balance-spring 10, with which the errors affecting the rotation period are reduced, can be formed.

Modifications of the first embodiment Next, the shell 50 according to each modification of the first embodiment will be described.

[0094] FIG. 9 is an explanatory view of the shell 50 according to a first modification of the present embodiment. [0095] FIG. 10 is an explanatory view of the shell 50 according to a second modification of the present embodiment.

In the shell 50 of the first embodiment, the recess 61 is formed only on a single end surface 56a in the axial direction of the shell 50 (refer to Fig. 7). On the other hand, the ferrule 50 of the first modification is different from that of the first embodiment in that the recess 61 is formed only on the other end surface 56b in the axial direction of the ferrule 50. By moreover, the ferrule 50 of the second modification is different from that of the first embodiment in that recesses 61a and 61b are formed on the two end surfaces 56a and 56b in the axial direction of the ferrule 50. Furthermore, with respect to configurations similar to the first embodiment, the detailed descriptions are omitted.

As shown in FIG. 9, in the first modified example, the recess 61 is formed on the other end surface 56b of the ferrule 50. Specifically, the recess 61 is formed by making the other end surface 56b of the support part 55 concave in the axial direction.

As shown in FIG. 10, in the second modification, the recesses 61a and 61b are formed on the end surface 56a and the other end surface 56b of the ferrule 50. Specifically, the first recess 61a is formed by rendering the end surface 56a of the support part 55 concave in the axial direction. Furthermore, the second step 61b is formed by making the other end surface 56b of the support part 55 concave in the axial direction.

Effects According to the present embodiment and the modifications of the present embodiment, since the recess 61 forms the reentrant 60 in the support part 55, compared to the case where the recess 61 is not present, the cross section of the heat propagation path by which the heat at the time of welding is transferred can be reduced. In this way, the heat transfer coefficient from the support part 55, to the main body 51 from the welding surface 57, can be reduced. Furthermore, the heat at the time of welding is transferred to the main body 51, around the recess 61, from the welding surface 57. In this way, compared to the case where the recess 61 is not present, since the propagation path heat from the welding surface 57 to the main body 51 is elongated, the heat transfer coefficient from the support part 55 can be decreased.

In this way, since it is difficult for the heat at the time of welding to transfer from the welding surface 57 to the main body 51, the annealing region is limited to the region extending from the welding surface. 57 to the vicinity of the recess 61. Consequently, since the part which is not annealed in the main body 51 of the shell 50 and which has a relatively high hardness can be thick for sure and it is possible to 'prevent the part having a relatively high hardness is thinned, cracks may appear in the main body 51 when the shell 50 is threaded by driving on the balance shaft 30 can be avoided.

Furthermore, since the reentrant 60 is produced in the form of the recess 61, the reentrant 60 can be produced simply by using electroforming, machining, or the like.

Method of Manufacturing the Ferrule Hereinafter, the method of manufacturing the ferrule 50 (refer to FIG. 6) of the first embodiment described above will be described with reference to the drawings.

[0103] FIG. 11 is a block diagram of the process for manufacturing the shell 50.

[0104] FIG. 12 is a view showing a state where an electroforming mold 94 is immersed in an electroforming liquid W.

[0105] FIG. 13 is a view showing a state where electroforming is carried out and a metal body 99 grows in an indentation hole 95.

As shown in FIG. 11, the method of manufacturing the shell 50 of the present embodiment includes an electroforming step S10, a thickness adjustment step S20 and a withdrawal step S30. Below, each step will be described.

S10 electroforming step First, the S10 electroforming step, in which the external shape of the shell 50 is formed (refer to FIG. 6), is carried out.

As shown in FIG. 12, in the electroforming step S10, the external shape of the shell 50 is formed using the electroforming mold 94 produced as below.

The electroforming mold 94 is produced using photolithography technology.

Specifically, firstly, after a silicon substrate 90 is prepared, a conductive film 91 which has gold, silver, copper, nickel, or the like as the main component is formed on the surface of the silicon substrate 90. Next, a first photosensitive material 94a is coated on the conductive film 91. In addition, the first photosensitive material 94a can be a positive savings or a negative savings. However, in this embodiment, negative savings are used. Then, the structuring is carried out according to the external shape of the shell 50, and the first photosensitive material 94a is exposed using a photoresist mask (not shown) in which the area other than the structured area is exposed. Since the first photosensitive material 94a is negative savings, the exposed part is hardened. Then, the first photosensitive material 94a is developed using a developing solution (not shown). Since the first photosensitive material 94a is negative savings, the area that has not been exposed is dissolved. Then, to form the contour of the recess 61 (refer to FIG. 6), a second photosensitive material 94b is coated on the first photosensitive material 94a. Furthermore, similar to what is described above, the second photosensitive material 94b is exposed and developed. In this way, the impression hole 95 is formed in the first photosensitive material 94a and the second photosensitive material 94b so as to follow the external shape of the shell 50 having the recess 61, the conductive film 91 is deposited, and the mold d electroforming 94 with which the ferrule 50 can be formed is produced.

In the electroforming step S10, firstly, the entire silicon substrate 90 is immersed in the electroforming liquid W which is contained in a treatment tank 96. Furthermore, when the electroforming step S10 is performed, the electroforming liquid W is selected according to the metal which is to be electroformed. For example, when nickel electroforming is performed, an amidosulfonic acid bath, a Watts bath, a sulfuric acid bath, or the like, is used.

If the nickel electroforming is carried out using the amidosulfonic acid bath, the amidosulfonic acid bath which has the nickel hydration salt of amidosulfonic acid as the main component is placed in the treatment tank 96 In addition, an anode electrode 97, which is made of the metal (nickel in the present embodiment) to be electroformed, is immersed in the amidosulfonic acid bath. For example, a plurality of balls which are made of metal to be electroformed are prepared, the metal balls are placed in a metal basket made of titanium or the like, and therefore, the anode electrode 97 is made.

Furthermore, after the silicon substrate 90 has been immersed in the amidosulfonic acid bath, the conductive film 91 formed on the silicon substrate 90 is connected to a cathode of an energy source 98, l The anode electrode 97 is connected to the anode of the power source 98, and electroforming is started. The metal of the anode electrode 97 is ionized, the metal ions move in the amidosulfonic acid bath, the metal ions are precipitated on the conductive film 91 deposited in the impression hole 95, to form the metal outline. , and the metal gradually grows. Furthermore, as shown in FIG. 13, the metal grows until the metal becomes the metal body 99 which completely blocks at least the impression hole 95. At this time, as described above, since the impression hole 95 has the external shape of the ferrule 50 (refer to FIG. 6) having the recess 61, the pushed metal body 99 then has the external shape of the ferrule 50 having the recess 61. When the external shape of the ferrule 50 is formed, the electroforming step S10 ends.

Step for adjusting the thickness S20 Then, the step for adjusting the thickness S20 is carried out in which the thickness of the metal body 99 is adjusted to become the thickness of the ferrule 50 (se refer to fig. 6).

In the thickness adjustment step S20, the silicon substrate 90 is raised from the treatment tank 96, and a method for cleaning the silicon substrate is carried out with pure water or the like. Then, the metal body 99 projecting from the impression hole 95 is removed, and the thickness of the remaining metal body 99 is adjusted to become the thickness of the ferrule 50 (see fig. 6). As a technique, polishing such as a CMP technique (a mechanical-chemical polishing technique) can be performed.

Removal step S30 [0116] Finally, removal step S30, by which the first photosensitive material 94a, the second photosensitive material 94b, the conductive film 91 and the silicon substrate 90 are removed.

In the removal step S30, the first photosensitive material 94a and the second photosensitive material 94b are removed by an incineration treatment, a peeling solution technique, or the like, and the silicon substrate 90 and the conductive film 91 are removed by the CMP technique or the like. In this way, the ferrule 50 can be produced by electroforming.

When the silicon substrate 90 and the conductive film 91 are removed, the removal step S30 ends, and the entire manufacturing process for the ferrule 50 ends.

Effects When the ferrule 50 is formed by electroforming, in most cases, nickel and a nickel alloy are adopted as the material. Here, in general, since the melting points of nickel and the nickel alloy are high compared to a metal like steel, the welding temperature when the hairspring 40 is welded to the ferrule 50 is high. However, according to the present embodiment, since the recess 61 is provided on the support part 55, the heat transfer coefficient of the support part 55 can be reduced, and the heat can be well radiated from the support part 55. In this way, even when the welding temperature is high, it is possible to prevent the main body 51 from being annealed. Consequently, the ferrule 50 having a special shape can be formed at low cost, and the cracks liable to appear in the main body 51 when the ferrule 50 is threaded by driving on the balance pin 30 can be avoided. In this way, the invention of the present embodiment is particularly suitable for the shell 50 which is produced by electroforming.

Second embodiment [0120] Next, a ferrule 50 according to a second embodiment will be described.

[0121] FIG. 14 is an explanatory view of the shell 50 according to the second embodiment. In addition, fig. 14 is a view from the side of the end surface 56a of the shell 50.

[0122] FIG. 15 is a sectional view along line C-C of FIG. 14.

In the shell 50 according to the first embodiment, the recess 61 is formed on the only end surface 56a of the shell 50, as a re-entrant 60 (refer to FIG. 7). On the other hand, as shown in fig. 14, the ferrule 50 of the second embodiment is different from the first embodiment in that a groove 64 is formed on the only end surface 56a of the ferrule 50, as a reentrant 60. Furthermore, for this which is similar configurations to the first embodiment, the detailed descriptions will be omitted.

The groove 64 is formed so as to extend along the circumferential direction of the main body 51, on the only end surface 56a of the ferrule 50. An inner side wall 64a, on the inner side and in the circumferential direction of the groove 64, is formed along the main body 51 so as to be at a predetermined distance from the opening 53 of the main body 51 and more outside in the radial direction than the main body 51. A outer side wall 64b, on the outer side and in the circumferential direction of the groove 64, is formed so as to be at a predetermined distance from the welding surface 57 of the support part 55. For example, the depth in the direction axial of the groove 64 is chosen to be approximately half the thickness, in the axial direction, of the main body 51. The groove 64 is formed, and therefore, an area with groove 55a where the groove 64 is present in the support part 55 is formed so as to be thinner, in the axial direction, than an area 55b where the groove is not present, more outward in the radial direction than the groove 64.

In the second embodiment, the weld core 71 can be formed on the other side of the end surface 56b (refer to FIG. 15). The reasons are as follows.

As shown in FIG. 8, in the first embodiment, the corner part between the single end surface 56a and the welding surface 57 is notched, and therefore, the recess 61 is formed. In this way, when the hairspring 40 and the ferrule 50 are welded to each other, it is necessary that the other flat end surface 56b adjoins the position adjustment tool 86 and is positioned with the another end surface 41b of the main hairspring body 41, and the hairspring and the ferrule are welded from the end surface side 56a.

On the other hand, in the second embodiment, as shown in FIG. 15, the innermost in the radial direction that the corner portion between the one end surface 56a and the welding surface 57 is notched, and the groove 64 is formed, the surface in the outer side in the direction radial and the surface in the inner side in the radial direction of the groove 64 are approximately level with each other. Consequently, when the hairspring 40 and the ferrule 50 are welded together, the end surface 56a and the other end surface 56b are not distinguished and adjoin the position adjustment tool 86 , and can be positioned with the end surface 41b of the main hairspring body 41. Therefore, since the welded surface is not limited to the end surface 56a from the side, the time of the positioning step at welding time can be shortened.

In the first embodiment, the welding surface 57 is formed on the area 55a where the step is present (refer to FIG. 7). On the other hand, in the present embodiment, the welding surface 57 is formed on the area 55b where the groove is not present. Therefore, it is preferable that the thickness, in the axial direction, of the area 55b where the groove is not present (i.e. the width, in the axial direction, of the welding surface 57 ) is thicker than the thickness, in the axial direction, of the hairspring 40 (that is to say that the width of the hairspring 40).

In addition, as shown in FIG. 15, the shortest distance between the internal side wall 64a of the groove 64 and the internal circumferential surface 53a of the opening 53, that is to say the shortest distance between the reentrant 60 and the opening 53, is denoted L3 and the shortest distance between the outer side wall 64b of the groove 64 and the welding surface 57, that is to say the shortest distance between the reentrant 60 and the welding surface 57, is denoted L4. The groove 64 is formed so that the following equation (3) is satisfied:

L3> L4 (3)

Effects of the second embodiment [0130] According to the second embodiment, the shortest distance L3 between the inner side wall 64a of the groove 64 and the opening 53 is greater than the shortest distance L4 between the outer side wall 64b of the groove 64 and the welding surface 57. In this way, when the inner side end 43 of the hairspring 40 is welded to the welding surface 57 of the ferrule 50, the region which is annealed due to the heat at the welding time is limited to the short distance from the welding surface 57 in the vicinity of the outer side wall 64b of the groove 64. Furthermore, since a heat transfer coefficient can be decreased by ensuring a long propagation path of heat to the main body 51, from the internal side wall 64a of the groove 64, the heat which is not radiated from the groove 64 is not easily transferred from the groove 64 to the main body 51.

Furthermore, since the groove 64 is present, since the support part 55 has a large surface area compared to the case where the groove 64 is not formed, the heat can be well radiated.

Therefore, since the part which is not annealed in the main body 51 of the shell 50 and which has a relatively high hardness can be thicker for sure and that it is possible to prevent more than the part having a relatively high hardness is thin, cracks likely to appear in the main body 51 when the ferrule 50 is threaded by driving on the pendulum axis 30 can be well avoided.

Furthermore, since the reentrant 60 is formed by the groove 64, this reentrant 60 can be simply formed using electroforming, machining, or the like.

Third embodiment [0134] Below, the shell 50 according to a third embodiment will be described.

[0135] FIG. 16 is an explanatory view of the shell 50 according to the third embodiment. Furthermore, in FIG. 16, the ferrule 50 is seen from the end surface side 56a.

[0136] FIG. 17 is a sectional view along line D-D of FIG. 16.

In the ferrule 50 according to the first embodiment, as re-entering 60, the recess 61 is provided on the only end surface 56a among the two end surfaces 56a and 56b in the axial direction of the ferrule 50 (refer to fig. 7). On the other hand, as shown in fig. 16, the ferrule 50 of the third embodiment is different from that of the first embodiment in that through holes 66 which communicate with two end surfaces 56a and 56b in the axial direction of the ferrule 50 are provided as reentrant 60. Furthermore, for the configurations similar to the first embodiment, the detailed descriptions are omitted.

As shown in FIG. 17, the through holes 66 are formed to communicate with the end surface 56a and the other end surface 56b of the ferrule 50. The internal circumferential surface 66a of the through hole 66 is formed to follow the outline of the portion of support 55 and the main body 51 farther outside, in the radial direction, than the main body 51. The internal circumferential surface 66a of the through hole 66 is formed to be at a predetermined distance from the welding surface 57 of the support part 55 and opening 53 of the main body 51. Furthermore, in the third embodiment, for reasons similar to those of the second embodiment, the weld core 71 can be formed on the other side end surface 56b (refer to fig. 17). In this way, also in the third embodiment, since the surface from which to weld is not limited to the end surface 56a, the time of the positioning step at the time of welding can be shortened.

In the first embodiment, the welding surface 57 is formed on the area 55a where the step is present (refer to FIG. 7). On the other hand, in the present embodiment, the welding surface 57 is formed on the area 55b where the hole is not present. Therefore, it is preferable that the thickness, in the axial direction, of the area 55b where the hole is not formed (i.e., the width, in the axial direction, of the welding surface 57 ) is thicker than the thickness, in the axial direction, of the hairspring 40 (that is to say that the width of the hairspring 40).

Similar to the second embodiment, the shortest distance between the internal circumferential surface 66a of the through hole 66 and the internal circumferential surface 53a of the opening 53, that is to say the shortest distance between the reentrant or the hole 60 and the opening 53, is denoted L3 and the shortest distance between the internal circumferential surface 66a of the through hole 66 and the welding surface 57, that is to say the shortest distance between the re-entrant or the hole 60 and the welding surface 57, is denoted L4. The through hole 66 is formed so that the following equation (3) is satisfied:

L3> L4 (3) [0141] 11 is preferable for the production of the through hole 66 to be carried out by electroforming. As described above, the electroforming mold 94 (see fig. 12) is produced using photolithography technology. Here, when the first photosensitive material 94a (refer to Fig. 12) is exposed, this first photosensitive material 94a is exposed using a photoresist mask (not shown) which has an opening in the area corresponding to through holes 66. Since the first photosensitive material 94a is a negative savings, the part corresponding to the exposed through hole 66 is hardened. Furthermore, if the first photosensitive material 94a is developed using a developing solution (not shown), the area which has not been exposed is dissolved, and the part corresponding to the exposed through holes 66 (refer to FIG. 16) stay. In this way, an electroforming mold 94, with which the ferrule 50 can be formed (refer to FIG. 16) having through holes 66, is produced. Furthermore, in the present embodiment, since the through holes 66 are formed only by the first photosensitive material 94a, it is not necessary to use the second photosensitive material 94b (refer to FIG. 12) to form the recess 61 (refer to fig. 6). Consequently, the ferrule 50 having a special shape which includes the through holes 66 can be formed at low cost by using the electroforming mold 94 produced as described above.

Effects of the Third Embodiment According to the third embodiment, since Equation (3) is satisfied, similarly to the second embodiment, when the inner side end 43 of the hairspring 40 is welded to the welding surface 57 of the shell 50, the portion which is annealed due to the heat at the time of welding is limited to the short distance from the welding surface 57 in the vicinity of the through holes 66. Furthermore, since the heat transfer coefficient can be decreased by ensuring a long path of heat propagation to the main body 51, from the through holes 66, the heat which is not radiated from the through holes 66 is not easily transferred from the through holes 66 to the main body 51. Consequently, since the part which is not annealed in the main body 51 of the shell 50 and which has a relatively high hardness can certainly be thicker and that it is possible to prevent more than the part having a relatively high hardness from being thin, cracks liable to appear in the main body 51 when the ferrule 50 is threaded by driving on the balance axle 30 may well be avoided.

In addition, since the through holes 66 are present at the support parts 55, the cross section of the heat propagation path, by which the heat is transferred at the time of welding, can be further reduced, and the coefficient heat transfer of the support portion 55 can be further decreased. Furthermore, the heat at the time of welding is transferred to the main body 51 around the through holes 66, from the welding surface 57. In this way, when the heat at the time of welding is transferred from the welding surface 57 to the main body 51, the linear heat propagation path which connects the welding surface 57 and the main body 51 is cut by the through holes 66. In other words, since the heat at the time of welding is transferred from the welding surface 57 at the main body 51 around the outer side in the radial direction of the through holes 66, the heat transfer coefficient of the support portion 55 can be further decreased. Therefore, since it is possible to further prevent the part having a relatively high hardness in the main body 51 of the ferrule 50 from being thin, cracks may appear in the main body 51 when the ferrule 50 is threaded through. hunting on the pendulum axis 30 can be well avoided.

Furthermore, since the hole 60 is formed by the through holes 66 and that these through holes 66 can be made simultaneously in addition to the main body 51 and the support part 55 of the ferrule 50 using electroforming, the hole 60 can be formed simply at low cost.

Furthermore, the technical scope of the present invention is not limited to the embodiments described above, and various modifications can be added to the scope of the present invention.

The external shape of the shell 50 is not limited to the embodiments. For example, in each embodiment, the outline of the main body 51 of the ferrule 50 is formed with an approximately elliptical annular shape. On the other hand, the outline of the main body 51 of the ferrule 50 can be formed in an approximately round annular shape. However, the shell 50 of each embodiment has advantages, namely that the expanded parts 51 a and 51 a, which expand in the first direction F, are formed in the main body 51 of the shell 50, the damage liable to 'Affecting the main body 51 when the ferrule 50 is threaded through is avoided because of the elastic force of the expanded parts 51a and 51a, and an appropriate holding force can be guaranteed with respect to the balance axis 30.

The shape of the reentrant 60 or the hole which is formed in the shell 50 is not limited to the embodiments. For example, the groove 64 of the second embodiment is formed only on the end surface 56a of the support portion 55. However, the groove 64 can be formed on two end surfaces such as the end surface 56a and the other end surface 56b of the support part 55.

Furthermore, in each embodiment, a reentrant 60 or a hole 60 is formed on the support part 55. The number of reentrants or holes 60 which are formed on the ferrule 50 is not limited to that in the embodiments. For example, in the second embodiment, a groove 64 is formed on a support part 55. However, several grooves 64 can be formed on a support part 55.

In each embodiment, the pair of support parts 55 and 55 is formed with a spacing of 180 ° in the circumferential direction of the main body 51. However, the pitch angle and the number in the circumferential direction of the support part 55 is not limited to each embodiment. For example, a support portion 55 can be formed. However, each embodiment has advantages, namely that the center of gravity of the ferrule 50 can be placed at the center of rotation level (that is to say the central axis O) of the ferrule 50 and the ferrule 50 can rotate stably without vibration. Furthermore, three support parts 55 can be provided with a spacing of 120 ° in the circumferential direction of the main body 51.

In the first embodiment, as a technique for welding the hairspring 40 to the shell 50, laser welding is given as an example. However, the welding technique is not limited to laser welding. For example, the hairspring 40 can be welded to the ferrule 50 using arc welding, resistance welding, friction stir welding, or the like. Since the re-entrant 60 is provided on the support part 55, the effects of the present invention can be obtained with any welding technique.

In the first embodiment, the reentrant 60 is formed by electroforming. However, the technique of making reentry 60 or hole 60 is not limited to this. For example, the re-entrant 60 or the hole 60 can be formed by machining.

Claims (10)

claims 1. Ferrule (50) for fixing an interior side end (43) of a hairspring (40) to a pendulum axis (30), comprising: a main body (51) which delimits a coaxial opening (53) with the pendulum axis (30) and which can be threaded on the pendulum axis (30); and a support part (55) which projects in a radial direction from an external side of the main body (51) and which is intended to support the hairspring (40), in which a welding surface ( 57), provided for welding therein the inner side end (43) of the hairspring (40) is formed by a lateral surface which the support part has in the radial direction, and a re-entrant (61; 64) or a hole (66 ) is present in at least one of two end surfaces (56a and 56b) of the end surface which the support part (55) has in an axial direction of the main body (51). 2. Ferrule (50) according to claim 1, in which the re-entrant (60) is a recess (61) where the end surface of the support part (55) is recessed in the axial direction, from a side region main body (51), up to the welding surface (57). 3. Ferrule (50) according to claim 1, wherein the reentrant (60) is a groove (64) which extends along a circumferential direction of the main body (51). 4. Ferrule (50) according to claim 1, wherein the hole (60) is a through hole (66) which communicates with the two end surfaces (56a and 56b) of the support part (55). 5. Ferrule (50) according to claim 2, in which the recess (61) is formed so that the relation L1> L2 is satisfied, where L1 is the shortest distance between a flange (62) of the recess (61) and the opening (53) and where L2 is the shortest distance between the flange (62) of the recess (61) and the welding surface (57). 6. Ferrule (50) according to claim 3 or 4, in which the reentrant or the hole (60) is formed so that the relation L3> L4 is satisfied, where L3 is the shortest distance between the reentrant or the hole ( 60) and the opening (53) and where L4 is the shortest distance between the re-entrant or the hole (60) and the welding surface (57). 7. Ferrule (50) according to one of claims 1 to 6, comprising: a plurality of support parts (55) in each of which a copy of the welding surface (57) and a copy of the reentrant or hole (60) are formed, in which the support parts (55) are formed at regular intervals in the circumferential direction of the main body (51). 8. Ferrule (50) according to one of claims 1 to 7, in which the ferrule (50) is a ferrule produced by electroforming. 9. balance spring (10) comprising a ferrule (50) according to claim 1, as well as a balance spring (40), the support part (55) of the ferrule (50) supporting the balance spring (40), and the inner rib end (43) of the hairspring (40) being welded to the welding surface (57) of the ferrule (50). 10. Timepiece (1) comprising a balance spring (10) according to claim 9.