CH711216A2 - A manufacturing method comprising a step of free cutting. - Google Patents

Abstract

The invention relates to a method for manufacturing a part (47), in particular a balance shaft, intended to be welded, comprising a machining step making it possible to form an oblique wall (44) between two perpendicular surfaces (41, 43 ) able to reduce the contact area of the face to be welded. The invention also relates to a method of manufacturing a watch component.

Description

Field of the invention

The invention relates to a method of manufacturing a face to be welded and, more specifically, such a face having an improved surface flatness.

Background of the invention

It is known from document PCT / EP 2015/061 774 to form a watch component from a part comprising a material based on silicon or ceramic which is directly welded by electromagnetic radiation to another piece such as, for example, for example, a metal or a metal alloy.

In the context of this development, it appeared important that the gap between the parts should not exceed 0.5 micrometer or they could not be welded.

Summary of the invention

The object of the present invention is to overcome all or part of the disadvantages mentioned above by proposing a new manufacturing method with at least one contact surface having an improved flatness allowing the assembly of parts by welding.

For this purpose, according to a first embodiment, the invention relates to a method for manufacturing a part comprising the following steps bring a bar; detaching the bar to form at least one diameter having a substantially vertical surface and a substantially horizontal surface; characterized in that the cutting step also forms an oblique wall between the substantially vertical surface and the substantially horizontal surface to reduce said surface substantially horizontal or in that the cutting step also forms a curved wall around said substantially horizontal surface so that the substantially horizontal surface is limited to a line.

According to the first embodiment, the manufacturing method advantageously allows to offer a face with a reduced welding surface, or even limit it to a contact line, to reduce the gap to a value guaranteeing its welding.

In addition, according to a second embodiment, the invention relates to a method for manufacturing a part comprising the following steps: bring a bar; detaching the bar to form at least one diameter having a substantially vertical surface and a substantially horizontal surface, characterized in that the cutting step also forms a puncture between the substantially vertical surface and the substantially horizontal surface intended to reduce the substantially vertical surface .

According to the second embodiment, the manufacturing method advantageously to ensure an isostatic configuration of the fitting of the part, to reduce the fitting gap to a value guaranteeing its welding.

[0009] Finally, whatever the embodiment, the invention relates to a method of manufacturing a watch component comprising the following steps: forming a first metal-based part from the method according to one of the preceding claims and a second part; mounting a surface of the first piece on a surface of the second portion; welding, by electromagnetic radiation of the laser type, the surface of the first portion mounted on the surface of the second portion to secure them.

According to other advantageous variants of the invention: the second piece is silicon-based or ceramic-based; the second piece further comprises at least a partial coating of metal, silicon oxide, silicon nitride, silicon carbide or a carbon allotrope; the first piece comprises an alloy of iron, a copper alloy, nickel or one of its alloys, titanium or one of its alloys, gold or one of its alloys, silver or one of its alloys, platinum or one of its alloys, ruthenium or one of its alloys, rhodium or one of its alloys or palladium or one of its alloys.

Brief description of the drawings

Other features and advantages will become apparent from the description which is given below, for information only and not limiting, with reference to the accompanying drawings, in which: <tb> fig. 1 <SEP> is a perspective view of a sprung balance resonator; <tb> fig. 2 <SEP> is a perspective representation of a hairspring according to the invention; <tb> fig. 3 <SEP> is a perspective representation of a balance shaft according to the invention; <tb> fig. 4 <SEP> is a sectional representation of an assembly according to PCT / EP 2015/061 774; <tb> fig. <SEP> is a sectional representation of an assembly according to a first embodiment of the invention; <tb> fig. 6 <SEP> is a sectional representation of an assembly according to a variant of a first embodiment of the invention; <tb> fig. 7 <SEP> is a sectional representation of an assembly according to an alternative of a first embodiment of the invention; <tb> fig. [SEP] is a sectional representation of an assembly according to a second embodiment of the invention; <tb> fig. <SEP> is a sectional representation of an assembly according to a combination of the first and second embodiments of the invention.

Detailed Description of the Preferred Embodiments

The invention relates to a component formed using a workpiece whose material does not include a usable plastic field, that is to say with a very small plastic area, with a second piece comprising the same type of material or another type of material.

This component has been devised for applications in the watchmaking field and is made necessary by the growing share of fragile materials such as those based on silicon or ceramic. It is possible, for example, to form a case, a dial, a flange, an ice, a telescope, a pusher, a crown, a caseback, a needle, a bracelet, a spiral, a pendulum, an anchor, a bridge, an oscillating weight or even a mobile like an escape wheel totally or partially based on fragile materials.

Preferably, the silicon-based material used for producing the compensating balance spring may be monocrystalline silicon regardless of its crystalline orientation, doped monocrystalline silicon whatever its crystalline orientation, amorphous silicon, porous silicon, polycrystalline silicon, silicon nitride, silicon carbide, quartz irrespective of its crystal orientation or silicon oxide. Of course other materials can be envisioned as a glass, a ceramic, a cermet, a metal or a metal alloy. In addition, the first silicon-based part may further optionally comprise at least one partial coating of silicon oxide, silicon nitride, silicon carbide or a carbon allotrope according to the intended applications of the watch component.

For simplicity, the explanation below will be focused on an assembly between a balance spring and a balance shaft. In fig. 1, we can see a resonator 1 in which the hairspring 5 is used to thermally compensate the whole of the resonator 1, that is to say all the parts and in particular the balance 3 mounted on the same shaft 7 balance. The resonator 1 cooperates with a maintenance system such as, for example, a Swiss lever escapement (not shown) cooperating with the pin 9 of the plate 11 also mounted on the shaft 7.

A compensating hairspring 15 is better visible in FIG. 2. It comprises a single blade 16 wound on itself between an inner coil 19 formed in form with a ferrule 17 and an outer coil 12 having an end 14 to be punctured. As shown in fig. 2, in order to improve the isochronism of the resonator in which the spiral 15 is used, the latter comprises an internal turn 19 comprising a Grossmann type curve and an outer turn 12 comprising a thickened portion 13 relative to the remainder of the spiral 15. Finally, it can be seen that the ferrule 17 comprises a single band extending in a substantially triangular shape so that the ferrule shows an elastic character when it is adjusted on the axis, in particular to allow its centering relative to the latter.

A shaft 27 is better visible in FIG. 3. It comprises in particular several diameters 22, 24, 26 for respectively receiving the hairspring, the balance and the plate. As shown in fig. 3, the diameter 22 comprises a cylindrical rod 21 bordered in its lower part by a bearing surface 23.

As illustrated in FIG. 4, the diameter 22 is intended to receive, between the rod 21 and the bearing surface 23, the ferrule 17 of the spiral 15. More specifically, the inner face 20 of the collar 17 is elastically pressed against the outer surface of the rod 21 and the lower face 18 of the shell 17 is pressed against the bearing surface 23. Finally, as visible under the reference 28, the rod 21 and / or the bearing surface 23 are welded to the shell 17 as taught in document PCT / EP 2015/061 774 .

However, as part of the development of the teaching of document PCT / EP 2015/061 774, it quickly emerged that the gap between the pieces should not exceed 0.5 micrometer or they would not can not be soldered.

According to a first embodiment, the manufacturing method comprises a step intended to décolleter the range of the shaft to provide a reduced welding surface, or even limit the contact to a line, to reduce the gap to a value less than or equal to 0.5 micrometer.

The method according to the first embodiment of the invention therefore comprises a first step intended to provide a bar adapted to undergo a bar turning. The example relates to an assembly between a spiral and a balance shaft, the bar may be based on metal or metal alloy.

The second step is intended to décolleter different diameters necessary to form the shaft 47 of balance and in particular the diameter 42 adapted to receive the shell 17 spiral 15. As shown in FIG. 5, in comparison with FIG. 4, the machining step is intended to voluntarily form an oblique wall 44 from the puncture of the cutting tool to the bearing surface 43 which is still substantially perpendicular to the surface of the rod 21 but with a much smaller width L that the scope 23 of FIG. 4. It is understood in the case of the shaft that the oblique wall 44 thus forms a cone.

Of course, according to a variant illustrated in FIG. 6, the second machining step could even be intended to voluntarily form an oblique wall 44 starting from the puncture of the cutting tool towards the bearing surface 43 forming a nip instead of the narrower surface 43 illustrated in FIG. fig. 5. It is understood in the case of the shaft that the oblique wall 44 thus forms a cone.

According to an alternative of the first embodiment illustrated in FIG. 7, the machining step could be intended to voluntarily form a curved wall 54 starting from the puncture of the cutting tool forming a contact line 53 more centered than the contact line 43 illustrated in FIG. 6. It is understood in the case of the shaft that the curved wall 54 thus forms a toric surface.

It is therefore understood that after the finishing steps comprising, for example, a burnishing step and possibly deburring, the shaft 47, 47, 57 provides a reduced welding surface 43, or even limit the contact at a line 43, 53, to reduce the gap to a value less than or equal to 0.5 micrometer.

It is therefore understood that, in a final welding step, the ferrule 17 is adjusted to the diameter 42, 42 or 52, that is to say between the surface of the rod 41, 41 or 51 and surface 43, 43 or 53, then is laser welded with a guarantee that the hairspring 15 and the shaft 47, 47 or 57 are secured.

According to a second embodiment, the manufacturing method comprises a step for detaching the stem of the shaft to ensure an isostatic configuration of the fitting of the ferrule on the shaft. It is understood that it is desired that the lower surface of the shell can adapt to the geometry of the scope, that is to say, can follow the geometry of the scope with more degree of freedom, to reduce the gap at a value less than or equal to 0.5 micrometer.

The method according to the second embodiment of the invention therefore comprises a first step for providing a bar adapted to undergo a bar turning. The example relates to an assembly between a spiral and a balance shaft, the bar may be based on metal or metal alloy.

The second step is to décolleter different diameters necessary to form the balance shaft 67 and in particular the diameter 62 adapted to receive the shell 17 of the spiral 15. As shown in FIG. 8, in comparison with FIG. 4, the free cutting step is intended to voluntarily form a puncture 64 more pronounced of the bar turning tool to the rod 61 but at a height H much narrower than the rod 21 of FIG. 4. It is understood in the case of the shaft that the rod surface 61 thus forms a cylinder.

Of course, according to a non-illustrated variant, the second machining step could even be intended to voluntarily form a stitch from the scope 63 of the cutting tool to the rod 61 forming a contact line instead of the smaller surface 61 shown in FIG. 5.

It is therefore understood that after the finishing steps comprising, for example, a browning step and, optionally, deburring, the resulting shaft 67 allows the lower surface 18 of the shell 17 to be able to adapt the geometry of the scope 63, that is to say, can follow the geometry of the scope 63 with more degree of freedom, to reduce the gap to a value less than or equal to 0.5 micrometer.

It is therefore understood that, in a final welding step, the ferrule 17 is adjusted to the diameter 62, that is to say between the surface of the rod 61 and the surface 63, and is then laser welded with a guarantee that the hairspring 15 and the shaft 67 are secured.

Of course, the present invention is not limited to the example shown but is susceptible to various variations and modifications that will occur to those skilled in the art. In particular, the first and second embodiments may be combined to benefit from their combined effects.

Thus, as shown in FIG. 9, the free cutting step could be intended to voluntarily form an oblique wall 76 starting from the puncture 74 of the cutting tool forming a contact surface 53 smaller than the contact surface 23 illustrated in FIG. 4. It is understood in the case of the shaft 77 that the oblique wall 76 thus forms a cone. In addition, the bar turning step may also voluntarily form a puncture 74 more pronounced of the bar turning tool to the rod 71 but at a height H much narrower than the rod 21 of FIG. 4. It is understood in the case of the shaft that the rod surface 71 thus forms a cylinder.

Then it is found that the shaft 77 thus advantageously provides a face 73 with a reduced welding surface to ensure its welding but also a face 71 of contact with a reduced surface ensuring an isostatic configuration of the adjustment on the 72 of the shaft 77 to further reduce the fitting gap further improving its welding even more.

Claims (7)

A method of manufacturing a workpiece (27, 47, 47, 57, 67, 77) comprising the steps of: - bring a bar; - detaching the bar to form at least one diameter (22, 24, 26, 42, 42, 52, 62, 72) having a substantially vertical surface (21, 41, 41, 51, 61, 71) and a surface (23, 43, 43, 53, 63, 73) substantially horizontal; characterized in that the cutting step also forms an oblique wall (44, 44, 76) between the substantially vertical surface (21, 41, 41, 51, 61, 71) and the surface (23, 43, 43 , 53, 63, 73) substantially horizontal in order to reduce said substantially horizontal surface. 2. A method of manufacturing a part (27, 47, 47, 57, 67, 77) comprising the following steps: - provide a bar; - detaching the bar to form at least one diameter (22, 24, 26, 42, 42, 52, 62, 72) having a substantially vertical surface (21, 41, 41, 51, 61, 71) and a surface (23, 43, 43, 53, 63, 73) substantially horizontal; characterized in that the cutting step also forms a curved wall (54) about said substantially horizontal surface (23, 43, 43, 53, 63, 73) so that the surface (23, 43, 43, 53 , 63, 73) substantially horizontal is limited to one line. 3. A method of manufacturing a part (27, 47, 47, 57, 67, 77) comprising the following steps: - provide a bar; - detaching the bar to form at least one diameter (22, 24, 26, 42, 42, 52, 62, 72) having a substantially vertical surface (21, 41, 41, 51, 61, 71) and a surface (23, 43, 43, 53, 63, 73) substantially horizontal; characterized in that the cutting step also forms a puncture (64) between the substantially vertical surface (21, 41, 41, 51, 61, 71) and the surface (23, 43, 43, 53, 63, 73) substantially horizontal to reduce the surface (21,41,41 ', 51,61,71) substantially vertical. 4. A method of manufacturing a watch component comprising the following steps: - forming a first piece (27, 47, 47, 57, 67, 77) based on metal from the method according to one of the preceding claims and a second piece (15); - mounting a surface (21, 23, 41, 43, 41, 43, 51, 53, 61, 63, 71, 73) of the first piece (27, 47, 47, 57, 67, 77) on a surface (18, 20) of the second portion (15); Welding, by electromagnetic radiation of the laser type, the surface (21, 23, 41, 43, 41 ', 43, 51, 53, 61, 63, 71, 73) of the first part (27, 47, 47 , 57, 67, 77) mounted on the surface (18, 20) of the second portion (15) to secure them. 5. Method according to the preceding claim, characterized in that the second part (15) is based on silicon or ceramic-based. 6. Method according to the preceding claim, characterized in that the second part (15) further comprises at least one partial coating of metal, silicon oxide, silicon nitride, silicon carbide or an allotrope of the carbon. 7. Method according to one of claims 4 to 6, characterized in that the first piece (27, 47, 47, 57, 67, 77) comprises an iron alloy, a copper alloy, nickel or a nickel. its alloys, titanium or one of its alloys, gold or one of its alloys, silver or one of its alloys, platinum or one of its alloys, ruthenium or one of its alloys, rhodium or one of its alloys or palladium or one of its alloys.