COMPONENT ESPECIALLY FOR HOROLOGY WITH SURFACE TOPOLOGY AND METHOD FOR MANUFACTURING THE SAME

Abstract

A system including two components intended to be in friction contact with each other in a given direction, wherein the friction occurs in a functional area, wherein the system is at least one of the two components including, on a surface in the functional area, a texture formed of a series of troughs of rounded shape separated by peaks or a series of bumps of rounded shape separated by troughs, the troughs extending parallel in the given direction and allowing for the evacuation of debris produced by friction and serving as a reservoir for a lubricant. A method for manufacturing at least one component or a mold by the DRIE (deep reactive ion etching) process, wherein surface defects on the sidewalls machined by the DRIE process are used to form the troughs.

Claims

1. A system comprising two components intended to be in friction contact with each other via friction surfaces in a given direction of friction, wherein the friction occurs in a so-called functional area, the system comprising at least one of the two components comprising, in the functional area, a surface having a texture formed of a series of troughs of rounded shape separated by peaks or a series of bumps of rounded shape separated by troughs, said troughs extending parallel to said given direction and allowing for the evacuation of debris produced by friction and serving as a reservoir for a lubricant.

2. The system according to claim 1, wherein said troughs are longitudinal and parallel to each other.

3. The system according to claim 1, wherein said troughs have a depth P which is greater than or equal to 100 nm and less than or equal to 1000 nm.

4. The system according to claim 1, wherein said series of troughs and peaks or bumps and troughs forms a periodic structure.

5. The system according to claim 1, wherein said texture is present on one sidewall of said at least one component machined by deep reactive ion etching.

6. The system according to claim 1, wherein each of the two components comprises said texture on one surface in the functional area, said troughs being disposed facing each other.

7. The system according to claim 1, wherein only said at least one component comprises said texture on its surface, the other component of the system having a smooth surface in the functional area.

8. The system according to claim 1, wherein said at least one component is made from silicon or from metal.

9. The system according to claim 1, wherein both components are timepiece components.

10. A timepiece comprising the system including two components intended to be in friction contact with each other via friction surfaces in a given direction of friction, wherein the friction occurs in a so-called functional area, the system comprising at least one of the two components comprising, in the functional area, a surface having a texture formed of a series of troughs of rounded shape separated by peaks or a series of bumps of rounded shape separated by troughs, said troughs extending parallel to said given direction and allowing for the evacuation of debris produced by friction and serving as a reservoir for a lubricant.

11. A mould intended to produce said at least one component comprising a series of bumps of rounded shape separated by troughs according to claim 1, wherein the mould includes on one of its faces a cavity with said texture formed of a series of troughs of rounded shape separated by peaks.

12. A method for manufacturing a mould or a component respectively made from silicon, the method including the following steps: (a) providing a blank made from silicon, (b) machining sidewalls on said blank by the deep reactive ion etching process to form the mould or the component, said machined sidewalls having a scalloped texture inherent to the deep reactive ion etching process, said texture defining on the machined sidewalls a set of troughs of depth P, wherein, at the end of the manufacturing method, said troughs are maintained on the machined sidewalls of the mould or of the component to form on said machined sidewalls channels able to collect debris or to receive a lubricant.

13. The method according to claim 12, wherein, at the end of the manufacturing method, said troughs on the machined sidewalls of the mould or of the component have a depth P greater than or equal to 100 nm and less than or equal to 1000 nm.

14. The method according to claim 12, wherein the machining step (b) is followed by an oxidation and deoxidation step (c) for reducing the depth P of the troughs, the depth P being maintained at a value greater than or equal to 100 nm at the end of said step (c).

15. The method according to claim 13 for manufacturing a mould, wherein said method comprises, after step (b) or step (c), a deposition step by electroforming a metal alloy on the machined sidewalls of the mould to produce another component.

16. The system according to claim 1, wherein said troughs have a depth P which is greater than or equal to 100 nm and less than or equal to 300 nm.

17. The system according to claim 2, wherein said troughs have a depth P which is greater than or equal to 100 nm and less than or equal to 1000 nm.

18. The method according to claim 12, wherein, at the end of the manufacturing method, said troughs on the machined sidewalls of the mould or of the component have a depth P greater than or equal to 100 nm and less than or equal to 300 nm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] FIGS. 1A and 1B schematically represent a system with two components, wherein one of the two components, on the friction surface thereof intended to be partially in contact with the other component, has a texture in the form of a series of scallops parallel to each other according to the invention. Friction occurs along a longitudinal direction parallel to the longitudinal direction of the troughs receiving the third body (FIG. 1A) and the lubricant (FIG. 1B).

[0019] FIGS. 2A and 2B represent a variant of the system with two components wherein one of the two components has a texture of complementary shape to that represented in FIGS. 1A and 1B.

[0020] FIG. 3A is a representation of a timepiece system comprising two components (escapement wheel/pallet lever) which, on the edge of the teeth and/or of the pallets, have a texture according to the invention. FIG. 3B schematically represents the texture on the etched wall.

[0021] FIG. 4 schematically illustrates, in a known manner, the various steps of the DRIE deep reactive ion etching process.

DETAILED DESCRIPTION

[0022] The present invention relates to components made from metal or from silicon comprising surfaces intended to be subjected to friction during use. The present invention thus relates more specifically to a system including two components having surfaces subjected to friction in a so-called functional area. In the field of horology, this may be, for example, a system of the following type: escape wheel/pallets, cam/sensor, click/toothed wheel, jumper/disc, coupling disc/spring, brake disc/brake lever, etc. The present invention also relates to the moulds that make it possible to produce these components by electroforming. It also relates to the method for manufacturing the components or moulds.

[0023] As represented schematically in FIGS. 1A-2B, at least one of the two components 2 of system 1 has, in the functional area of its friction surface, a surface topology that, on the one hand, facilitates the evacuation of third-body particles and, on the other hand, forms a reservoir for the lubricant.

[0024] Referring to FIGS. 1A and 1B, the surface topology is formed of periodic scallops parallel to each other with troughs 3a, also called hollows, of rounded shape separated by peaks 3b. According to this variant, the contact between the two components 2 occurs on peaks 3b of the structure. The longitudinal dimension of troughs 3a extends parallel to the direction of friction in the functional area and the troughs serve as reservoirs for lubricant 5 and channels for evacuation of friction debris 4. According to the invention, depth P of the troughs which is the distance between the low point of the trough and the top of the peak is typically greater than or equal to 100 nm and less than or equal to 500 nm (FIG. 3B).

[0025] In FIGS. 2A and 2B, the structure has a series of rounded bumps 3c separated by troughs 3a. This structure is obtained by electroforming metal components in moulds having the scalloped structure of FIGS. 1A and 1B. Depth P of the hollows thus corresponds here to the distance between the low point of the trough and the top of the bump and is of course equal to the aforementioned depth P. According to this other variant, the contact between the two components 2 occurs at the top of bumps 3c of the texture.

[0026] In the variants presented in FIGS. 1A-2B, only one of the two components includes troughs, the other component having a substantially smooth friction surface in the functional area. According to another variant that is not represented, the two components can have troughs in this area which face each other and together form debris evacuation channels and lubricant reservoirs.

[0027] By way of illustration, FIG. 3A represents a timepiece system 1: escape wheel 6/pallet lever 7 wherein one or both components 6, 7 have, at least on the sidewall 8a, 9a of teeth 8 and/or pallets 9 that is subjected to friction, a texture according to the invention (FIG. 36).

[0028] This surface texture is obtained during machining of the component or of the mould by the DRIE process which is a plasma etching process that includes two different cycles that succeed one another, namely an etching cycle and a passivation cycle. The method is schematically represented in FIG. 4. In a known manner, a silicon blank 10 is provided. A perforated mask 11 defining the trench to be machined is formed on the surface of blank 10 (FIG. 4a). The method then consists in the series of steps of etching (FIG. 4b) in fluorinated gas (e.g. SF.sub.6) and of passivation (layer 12) using fluorocarbon gas (e.g. C.sub.4F.sub.8), wherein the alternate etching and passivation steps produce the scalloped structure on the etched sidewall. The periodicity and depth of the troughs can, in a known manner, be adjusted by changing, amongst other things, the etching and passivation sequence times. (for example, 6 of etching2 of passivation, or 3 of etching1 of passivation). Preferably, the etching phase durations are greater than the passivation phase durations. Typically, these troughs have a depth P comprised between 100 and 1000 nm and preferably on the order of a few hundred nanometres with a trough periodicity comprised between 1.5 and 6 m and preferably on the order of 3 m.

[0029] Optionally, to reduce the depth of the troughs, without thereby removing surface roughness, an oxidation step followed by a deoxidation step can be envisaged (not represented). This step consists in performing thermal oxidation at temperatures typically comprised between 900 and 1200 C. followed by chemical deoxidation typically in hydrofluoric acid. By way of example, trough depth P can thus be reduced from 300 nm to 100-200 nm during this step.

[0030] Then, when the aforementioned method is used to manufacture a mould, the method further includes a deposition step by electroforming a metal alloy on the textured surface of the mould to produce the component with a series of bumps and troughs on its surface.

LEGEND

[0031] (1) System of components [0032] (2) Component [0033] (3) Scalloped structure [0034] a) Trough or hollow [0035] b) Peak [0036] c) Bump [0037] (4) Debris [0038] (5) Lubricant [0039] (6) Escape wheel [0040] (7) Pallet-lever [0041] (8) Escape wheel tooth [0042] a. Edge or sidewall [0043] (9) Pallets [0044] a. Edge or sidewall [0045] (10) Blank [0046] (11) Mask [0047] (12) Passivation layer