CH705464A2 - Ring for assembling hairspring on balance staff in mechanical clock movement, has nose comprising receiving surface that forms outer contour of ring at radial end of nose remote from pivot axis, and forms point of ring remote from axis - Google Patents

Abstract

The ring (1) has a receiving and centering unit (6) for receiving and centering a balance staff with respect to a pivot axis (D). The unit has a nose (2) projecting radially with respect to the axis and comprising a receiving surface (4) to receive an end of a hairspring. The unit forms a female prism extending parallel to the axis according to a profile. The receiving surface is located on an edge (7) parallel to the axis. The receiving surface forms an outer contour of the ring at a radial end of the nose remote from the axis, and forms a point of the ring remote from the axis. An independent claim is also included for a balance-hairspring assembly.

Description

Field of the invention

The invention relates to a clockwork ferrule for driving on a balance shaft and for mounting a spiral on said balance shaft, said ferrule having means for receiving and centering a said axis of rocker relative to a pivot axis, and having, projecting radially relative to said pivot axis, a first nose with a receiving surface for receiving an end of said spiral.

The invention also relates to a ferrule-spiral assembly comprising a spiral fixed on such a ferrule.

The invention relates to a sprung balance assembly comprising a balance shaft and such a ferrule-spiral assembly.

The invention relates to the field of mechanical watchmaking, and more particularly the regulating assembly.

Background of the invention

In a watchmaking mechanical movement, the ferrule is the assembly interface of the balance spring. Generally it is a washer driven on the balance shaft, and having at least one attachment point of the inner end of the spiral. This attachment is done using a conical pin, or by gluing, or by welding. The method of fixing by welding, and in particular by laser welding, allows the realization of the ferrule steel bar turning.

The ferrule is small in size to have only a small influence on the moment of inertia of the sprung-balance assembly, and not to introduce unbalance.

The ferrule also contributes to the regularity of the regulating organ. It is necessary, after its driving on the axis of balance, to be able to turn it without difficulty to carry out the setting at the mark, that is to say the alignment of the plate anchor and the anchor-pendulum axis to the point death. This hunting must have the smallest possible influence on the maintenance of a given distance between the axis of balance and the point of attachment, and the outer contour of the ferrule must not disturb the active length of the curve in the center of spiral.

When the ferrule is made of special steel, the friction torque on the balance shaft after driving may be too important and make it difficult to set the benchmark. To remedy this drawback, patent CH 347 142 describes a slot of elasticity between the hole of axis and the edge of the ferrule, for a perfectly circular ferrule on which the spiral is fixed by means of a conical pin located in the plane of symmetry passing through the axis and the slot.

Patent CH 508 233 describes a ferrule of the same type, spiral riveted or glued in a groove, of asymmetrical shape in racket with a shift of the axis hole, to eliminate the risk of support of the first turn on the edge of the ferrule. These split rings with a circular axis hole, however, have two disadvantages. When driving on the balance shaft, the movement of the attachment point is not controllable with great rigor, and when performing the benchmarking the risk is great to cause disruption of flat and centering.

To reduce the friction torque facilitating the setting benchmark without having to make a slot, US Patent 3,429,120 describes a two-piece shell having an inner barrel of brass, or other non-ferrous material, and an outer portion of steel to allow the welding of the curve inside the spiral. However, manufacturing and assembly costs are high.

To reduce the friction torque in a special steel ferrule without elastic slot, it can reduce the friction surface to discrete contacts between the balance shaft and the ferrule opening opening. Patent CH 311287 consists in ovalizing a hole initially having a circular shape, the outline of the ferrule retaining its initial circular shape. Having only two symmetrical points of support, we find the same problems as those mentioned for the split ferrule.

Patent CH 466 807 and US 3,430,435 give the ferrule opening opening a regular polygonal contour illustrated by an equilateral triangle with broken angles, or an opening of hypocycloidal shape. In this embodiment, the points of tightening of the ferrule on the axis have an equidirectional distribution and the ferrule has a regular contour and inscribed in a circle, to avoid unbalance problems, but having in return the disadvantage of present a risk of contact of the coil in the center.

The known achievements, type ferrule "Greiner" or "Nivatronic", the most used on quality achievements, are expensive to produce, usually obtained by bar turning and milling.

Summary of the invention

The invention proposes to create a ferrule of low cost of implementation, and whose design allows to facilitate assembly. In particular, a usual operation when assembling the balance spring to the balance shaft through the ferrule is to conduct a flat centering of the spiral relative to the balance shaft. This flat centering operation is performed manually on the assembled assembly, requires special know-how, is expensive, and also has the risk of hurting the pivots. It is therefore necessary to overcome the flat centering by a very good geometric accuracy of perpendicularity of the spiral plane with respect to the axis of pivoting of the balance.

It is, again, to simplify correlatively the execution of the balance shaft, substituting the usual conical bearing in the prior art a simple cylindrical scope, associated with a single stop constituted by a shoulder, a dish or the like.

The invention must, still, allow a good positioning of the spiral relative to the ferrule. In the existing solution, the hairspring is welded to the shell by at least one point, in particular by laser welding, after having been cut to length. There is an angular uncertainty on the cut, of several degrees, which can represent a surplus of important material beyond the welding.

For this purpose, the invention relates to a timepiece for hunting on a balance shaft and for mounting a hairspring on said balance shaft, said ferrule comprising receiving means and centering of a said axis of balance relative to a pivot axis, and having, projecting radially relative to said pivot axis, a first nose with a receiving surface for receiving an end of said spring, characterized in that said means for receiving and centering constitute a female prism extending parallel to said pivot axis according to a profile arranged to carry according to at least three generatrices on a said balance shaft, and further characterized in that said receiving surface is located on a parallel edge to said pivot axis and constituting the outer contour of said shell at the radial end of said first nose furthest from said pivot axis and also constituting the point of said ferrule furthest from said pivot axis.

According to a feature of the invention, said profile comprises a regular polygon whose faces are intended to cooperate with the generatrices of a said balance shaft to ensure its centering.

According to a feature of the invention, said ferrule comprises at least one complementary angular identification element arranged to cooperate with an angular registration element of a said balance shaft.

According to a feature of the invention, said ferrule comprises, on either side of said edge, an upper surface and a lower plane surface parallel to one another and perpendicular to said pivot axis.

According to another characteristic of the invention, said receiving surface comprises, at the point farthest from said pivot axis, a cylindrical surface of small radius centered on the side of said ferrule, on the radial end of said pivot axis. passing through that point.

According to a feature of the invention, said ferrule comprises, close to said receiving and centering means, an abutment surface arranged to cooperate with a shoulder of a said balance shaft when it includes one, for the axial adjustment relative positioning of said ferrule with the latter.

The invention also relates to a ferrule-spiral assembly comprising a spiral fixed on such a ferrule, characterized in that said spiral is locally tangential to said receiving surface in a contact segment parallel to said pivot axis cooperating in contact with a generatrix of said receiving surface, and any normal said spiral at a point of said contact segment is secant with said pivot axis.

According to a feature of the invention, any normal spiral coil at a point of said contact segment passes through the point of said receiving surface furthest from said pivot axis, and coincides with the radial end of said pivot axis and passing through said point.

According to a characteristic of the invention, said receiving surface comprises, at the point furthest from said pivot axis, a cylindrical surface of radius centered on a radial end of the pivot axis, the value of said radius being less than or equal to the radius value of the inner end of said hairspring.

The invention also relates to a sprung-balance assembly comprising a balance shaft and such a ferrule-spiral assembly, characterized in that said balance shaft is cylindrical at one of its ends for driving said ferrule.

According to a feature of the invention, said balance shaft comprises an axial abutment arranged to cooperate in abutment abutment with an abutment surface that includes said ferrule.

In a preferred embodiment, the ferrule according to the invention is flat, and made by stamping, and cut in the strip, which is both reliable and economical.

The first protruding nose relative to the rest is a safety factor, avoiding the spiral comes to touch another point of the ferrule during its contraction. For reasons of balance, the ferrule according to the invention may comprise other noses, or a particular contour, the important thing being that their radial size is less than that of the contact surface of the first nose.

The invention can weld the spiral other than the middle of the nose, which solves the positioning problem.

In an advantageous version, the first nose is thin, and has a relatively short contact surface, which allows a better positioning of the hairspring, in terms of concentricity with respect to the pivot axis.

Advantageously, the interface profile with the balance axis comprises a regular polygon in which is written a circle, for example equilateral triangle or regular hexagon. This arrangement improves the guidance and hunting.

The flat spiral, that is to say the perpendicularity of the spiral plane relative to the axis of pivoting of the balance, is guaranteed, preferably, by a bearing shoulder on the balance shaft.

Brief description of the drawings

Other features and advantages of the present invention will appear in the description which follows, with reference to the appended drawings in which: <tb> - fig. 1 <sep> shows, schematically and in plan view, a first embodiment of a ferrule according to the invention; <tb> - fig. 2 <sep> represents, schematically and in side view, the ferrule of FIG. 1; <tb> - fig. 3 <sep> shows, schematically and in plan view, a detail of another embodiment of a ferrule according to the invention; <tb> - fig. 4 <sep> shows, schematically and in plan view, a detail of a first embodiment of nose of receiving the hairspring of a ferrule-hairspring assembly comprising a ferrule according to the invention, this nose having an evolutive radius; <tb> - fig. 5 <sep> represents, schematically and in plan view, a detail of a second variant of the receiving nose of the hairspring of a ferrule according to the invention, this nose having a radius centered on a radial resulting from the pivot axis of the balance, and the spiral being shown welded at the axis of symmetry of this radius; <tb> - figs. 6 and 7 <sep> represent, in a similar manner to FIG. 5, the same variant, with the spiral welded on either side of this axis of symmetry; <tb> - fig. 8 <sep> represents, schematically, partially and perspective, a sprung-balance assembly comprising a balance shaft and such a ferrule-spiral assembly, the spiral being represented only by the end of its inner coil.

Detailed Description of the Preferred Embodiments

The invention relates to the field of mechanical watchmaking, and more particularly the regulating assembly.

The invention relates to a watch ring 1 for driving on a balance shaft 20, and for mounting a spiral 11 on such a balance shaft 20.

This shell 1 comprises receiving means and centering 6 for cooperating with such a balance shaft 20, the driving being carried out in the direction of a pivot axis D, and the centering along the same axis.

The ferrule 1 comprises, protruding radially from the pivot axis D, a first nose 2 with a receiving surface 4 for receiving an end of the spiral 11.

According to the invention, these receiving and centering means 6 constitute a female prism extending parallel to the pivot axis D according to a profile arranged to carry according to at least three generatrices on such a balance shaft. Prism here means the surface generated by the translation, parallel to itself, of a given closed profile, in a direction which is in this case the rectilinear direction constituted by the pivot axis D.

According to the invention, the receiving surface 4 is located on a lip 7 parallel to the pivot axis D and constituting the outer contour of this shell 1, at the radial end of the first nose. 2 farthest from the pivot axis D. The receiving surface 4 is also the point of the sleeve 1 furthest from the pivot axis D.

Preferably, the basic profile of the receiving and centering means 6 comprises a regular polygon, circumscribed to a circle, and whose faces are intended to cooperate with the generatrices of a balance shaft 20 to ensure its centering.

The ferrule 1 advantageously comprises at least one complementary angular identification element arranged to cooperate with an angular identification element of such a balance shaft 20.

In the preferred embodiment, you! that visible in the figures, the ferrule 1 comprises, on either side of the edge 7, an upper surface 8 and a lower surface 9 plane parallel to each other and perpendicular to the pivot axis D.

In a preferred embodiment, the ferrule according to the invention is flat, and made by stamping, and cut in the strip, which is both reliable and economical.

The receiving surface 4 can take different geometries.

FIG. 1 shows a ferrule 1, with a convex portion of the first nose 2 along the ferrule, which is cut, which consists of three rays.

FIG. 4 shows an evolving radius profile, symmetrical with respect to a plane of symmetry passing through the pivot axis D and a radial A from it, a radius R1 value is framed by radii of lower value. The receiving surface 4 thus comprises, at the point P furthest from the pivot axis D, a cylindrical surface of small radius R1 centered, preferably smaller than the radius of curvature of the spiral at the point of contact, on the the shell 1, on the radial A from the pivot axis D passing through the point P.

Figs. 5 to 7 illustrate a preferred embodiment in which the receiving surface 4 comprises, at the point P furthest from the pivot axis D, a cylindrical surface of radius R2 centered on the pivot axis D. FIG. 5 illustrates a case where the hairspring 11 is fixed, in particular welded, at the plane of symmetry of this radius R2. Figs. 6 and 7representent, similarly to FIG. 5, the same variant, with the spiral 11 welded on either side of this plane of symmetry, or on both sides for example in case of welding at two points, and a plane B locally normal to the spiral at level of its contact surface with the receiving surface 4 thus passes through the pivot axis D.

The minimum contact between the spiral 11 and the ferrule 1 is that of the surface of the weld point, or weld points if there are several. In practice, one point may suffice, an alternative embodiment consists of executing two points, one at the upper surface 8 and one at the bottom surface 9 of the shell, "between leather and flesh" that is to say with a laser beam parallel to the pivot axis D and aiming exactly the interface between spiral and ferrule, two opposite laser beams can be used for this operation. The particular configuration of the shell makes that, in practice, according to the invention, the contact surface between the spiral 11 and the shell always comprises at least one line segment parallel to the pivot axis D.

This arrangement ensures the correct positioning of the spiral relative to the ferrule. When the hairspring is presented flat on a bearing surface which is the same as one of the faces of the shell, for its attachment by welding or the like on the latter, the flat positioning is ensured, and the objective of the invention is thus achieved.

Preferably, the ferrule 1 comprises, close to the receiving and centering means 6, an abutment surface arranged to cooperate with a shoulder of a said balance shaft 20 when it includes one, for the axial adjustment relative positioning of the ferrule 1 with the latter. This abutment surface consists, in the simplest and least expensive version of the ferrule 1 flat with two parallel faces 8 and 9, in one of these two faces. In other variants, it may consist of a counterbeam, or the like.

The invention also relates to a ferrule-spiral assembly 10 having a spiral 11 attached to a shell 1.

This hairspring 11 is locally tangential to said receiving surface 4 in a contact segment 13 parallel to the pivot axis D cooperating in contact with a generator 5 of the receiving surface 4, and in a preferred embodiment because giving good results as regards the operation of the hairspring, any normal B to the hairspring 11 at a point of the contact segment 13 is intersecting with the pivot axis D.

In the embodiment of FIGS. 4 and 5, any normal B spiral 11 at a point of the contact segment 13 passes through the point P of the receiving surface 4 furthest from the pivot axis D, and coincides with the radial A from this axis of pivoting D and passing through the point P.

Preferably, the receiving surface 4 comprises, at the point P furthest from the pivot axis D, a cylindrical surface of radius R2 centered on the pivot axis D, the value of said radius R2 being less than or equal to the value of the radius RS of the inner end of the spring 11 at the level of the contact segment 13.

The invention also relates to a sprung-balance assembly 100 comprising a balance shaft 20 and such a ferrule-spiral assembly 10.

Preferably, the balance shaft 20 is cylindrical at one of its ends for driving the ferrule 1.

Advantageously, the balance shaft 20 comprises an axial abutment arranged to cooperate in abutment abutment with an abutment surface that includes the ferrule 1.

The invention is well suited to an execution of the ferrule by stamping in a band, in particular metal. The accuracy of perpendicularity of the spiral 11 with the balance shaft 20 is ensured, as is the clamping value of the balance shaft 20 in the housing constituted by the receiving and centering means 6.

Preferably, the ferrule according to the invention is made of "Durnico" because this alloy is well cut and welded well to the spiral and does not require surface treatment, such as nickel plating or other, which contributes to low cost of carrying out the invention. It may, again, and without limitation, be made of other materials: carbon steel, Ck67, Ck75 or Ck101, 15P or 20AP, or the like; ferritic stainless steel austenitic stainless steel cobalt base alloy, "Phynox" or the like brass nickel Cube CuNiSn: "Pfinodal", "Declafor", or the like aluminum or aluminum alloy titanium or titanium alloy.

The positioning of the spiral on the ferrule is always optimal, the fact that locally the inner end of the spiral is tangent to the ferrule ensures a perfect geometry of the whole.

In the case where, in particular for balancing reasons, it is desired to equip the ferrule 1 with other arms or nose 3, these must remain in a cylindrical envelope, centered on the pivot axis D, d a radius R3 of value less than the radius R2 of the end of the first nose 2.

Claims (11)

1. Watch ring (1) for driving on a balance shaft and for mounting a balance spring (11) on said balance shaft, said collar (1) comprising receiving and centering means (6) of a said balance shaft with respect to a pivot axis (D), and having, projecting radially relative to said pivot axis (D), a first nose (2) with a receiving surface (4) for receiving one end of said hairspring (11), characterized in that said receiving and centering means (6) constitute a female prism extending parallel to said pivot axis (D) in a profile arranged to carry according to at least three generators on a said balance shaft, and further characterized in that said receiving surface (4) is located on a lip (7) parallel to said pivot axis (D) and constituting the outer contour of said ferrule (1) at the level of the radial end of said first nose (2) farthest said pivot axis (D) and also constituting the point of said ferrule (1) furthest from said pivot axis (D). 2. Ferrule (1) according to the preceding claim, characterized in that said profile comprises a regular polygon whose faces are intended to cooperate with the generatrices of said balance shaft to ensure its centering. 3. Ferrule (1) according to one of the preceding claims, characterized in that it comprises, on either side of said edge (7) an upper surface (8) and a lower surface (9) parallel planes l ' to one another and perpendicular to said pivot axis (D). 4. Ferrule (1) according to one of the preceding claims, characterized in that said receiving surface (4) comprises, at the point (P) furthest from said pivot axis (D), a cylindrical surface of small radius ( R1) centered on the side of said shell (1), on the radial (A) from said pivot axis (D) passing through said point (P). 5. Ferrule (1) according to one of the preceding claims, characterized in that said receiving surface (4) comprises, at the point (P) furthest from said pivot axis (D), a cylindrical surface of radius (R2 ) centered on said pivot axis (D). 6. Ferrule (1) according to one of the preceding claims, characterized in that it comprises, in the vicinity of said receiving and centering means (6), an abutment surface arranged to cooperate with a shoulder of a said shaft balance when it has one, for the axial adjustment relative positioning of said ferrule (1) with the latter. 7. Ferrule-spiral assembly (10) comprising a spiral (11) fixed on a ferrule (1) according to one of the preceding claims, characterized in that said spiral (11) is locally tangential to said receiving surface (4) in a contact segment (13) parallel to said pivot axis (D) cooperating in contact with a generatrix (5) of said receiving surface (4), and that any normal (B) to said spiral (11) at a point said contact segment (13) is intersecting with said pivot axis (D). 8. The ferrule-spiral assembly (10) according to the preceding claim, characterized in that any normal (B) to said spiral (11) at a point of said contact segment (13) passes through the point (P) of said receiving surface (4) farthest from said pivot axis (D), and is coincident with the radial from said pivot axis (D) and passing through said point (P). 9. A ferrule-spiral assembly (10) according to claim 7 or 8, characterized in that said receiving surface (4) comprises, at the point (P) furthest from said pivot axis (D), a cylindrical surface of radius (R2) centered on said pivot axis (D), the value of said radius (R2) being less than or equal to the radius value (RS) of the inner end of said hairspring (11). 10. A sprung balance assembly (100) comprising a balance shaft (20) and a ferrule-spiral assembly (10) according to one of claims 7 to 9, characterized in that said balance shaft (20) is cylindrical to one of its ends for driving said ferrule (1). 11. Spiral balance assembly (100) according to claim 10, characterized in that said balance shaft (20) comprises an axial abutment arranged to cooperate in abutment abutment with a stop surface that comprises said ferrule (1).