EP1753581A1 - Method of producing a micro- or nano-mechanical part, comprising a femto-laser-assisted ablation step - Google Patents

Abstract

The invention relates to a method of producing a micro- or nano-mechanical part, such as a pulley or belt for clock making, comprising a laser ablation step which is performed with the aid of a femto-laser, i.e. a laser having a pulse with a duration of less than 5x10-13 seconds and a power of more than 1012 watts on the beam/material interaction surface. According to the invention, the part to be machined is pre-modelled in three dimensions and said three-dimensional model is used to generate the machining programme.

Description

 METHOD FOR MANUFACTURING A MICRO- OR NANOMECHANICAL PART BY A LASER ABLATION STEP USING A FEMTOLASER

Technical area

The present invention relates to a method for manufacturing micromechanical and nanomechanical parts.

The present invention also relates to parts manufactured according to this method, and intended for applications in watchmaking, or outside watchmaking, for example in the field of measuring instruments, optics, optoelectronics, or in other areas requiring significant machining precision, excluding the ablation of biological materials. The present invention also relates to methods of manufacturing transmission members, such as belts, pulleys, gears, etc., for horological applications in particular.

State of the art

International application WO04006026 describes a watch movement using pulleys and belts as a transmission. Watch movements with gears, or other types of synchronous or asynchronous transmission, are widely known. However, there is a constant need to miniaturize the components of such movements.

The manufacture of these different transmissions is subject to severe constraints due to the dimensions and the materials which it is desired to use. The requirements in terms of geometry and precision are severe. Thus, the manufacture of flexible mechanical transmission elements, for example belts, or of mechanical, flexible or rigid members, often of small size and made from non-metallic, polymeric, organic or composite materials, poses significant difficulties. . Organ dimensions are often less than 2 mm and the teeth pitch less than 2 mm, or even of the order of a hundredth of a millimeter.

The following problems arise for those skilled in the art: difficulty in machining and controlling machining, - behavior of materials (physicochemical properties) difficult to control, modeling, then reproduction of complex surfaces, in particular lefts, unsuitable. difficulty in using laminated or composite materials, - definition of functional shapes, for example the teeth, difficult to introduce, absence of tensile reinforcements or envelope with low coefficient of friction in the case of belts.

There is therefore a need in the prior art for new methods of manufacturing micro- and nano-mechanical components which allow machining on a dimensional scale (resolution) varying from millimeter (10 ^{~ 3} meter) to nanometer (10 ^'9 metre). Advantageously, this process should be suitable for all materials without distinction, or in any case for large classes of materials. The machining should be based on a geometric description of the micro- or nano-mechanical components to be machined, for example transmission elements.

There is also a need for new parts or components, for example for new pulleys and belts, with reduced dimensions and unequaled manufacturing tolerances, which cannot be manufactured with conventional manufacturing processes and which therefore do not not been imagined before. Methods for machining parts by power laser are known in the prior art. Thus, the use of laser diodes YAG or C02 continuous or with “long” pulses (more than 500 femto-seconds) is relatively conventional in the machining of materials such as metals or excimer for polymers. These processes are limited when working on small dimensions or on materials that do not withstand shocks or thermal stresses. It has in fact been observed that the transmission of heat in the material during the pulses, or even continuously, limits the precision of the ablation zone. Furthermore, the ablation zone of ordinary lasers corresponds to the cylinder shape of the beam, which limits the shapes that can be machined. The depth of machining depends on the power of the beam and the characteristics of the material; it is difficult to master.

Brief summary of the invention

The method of the invention is based on the machining of small members by ablation of material by means of ultra-short pulse lasers. In particular, the invention is based on ablation by means of laser pulses of a duration of less than five hundred femto seconds less than 5χ10 ^"13 seconds and of a power greater than 10 ¹² watts on the beam interaction surface Such pulses are generated by particular lasers, called femto-lasers below.

Femto-lasers are known per se and their technology is well mastered today, so that these devices are compact, versatile and reliable. The diversity of these lasers continues to increase: the beams obtained today cover the entire electromagnetic spectrum, from X-rays to T-rays (terahertz radiation, located beyond infrared), and the maximum powers reach several petawatts (several billion megawatts). These devices are particularly applicable in physics, chemistry, biology, medicine, optics.

Because of the extremely short duration of their impulses, they make it possible to study the ultra-rapid phenomena occurring at microscopic or atomic scale. In addition, very high powers can be produced during the short duration of the pulse, creating extreme conditions, often comparable to those encountered in fusion reactors. The use of the ultra-short pulse laser for the machining of mechanical micro-organs has the following advantages: machining precision, ablation of material under almost athermal conditions, there is only effect at the focal point "beam waist", the beam can, in particular in the case of transparent materials, pass through thicknesses to go to work at a point in the mass without altering the surface or the material on the path traveled, the beam is manipulated from a distance and under all the angles, ^r there is no restriction on the level of the machined materials, - we can obtain a resolution finer than the width of the laser beam by adjusting the laser so that only the intensity of the central part, where the greatest power is concentrated, ie greater than the ablation threshold of the material (control of the energy density in the focal plane), - absence of machining forces at the level of the ablation plane.

The use of femto-laser for the ablation of materials is known per se, and described in the articles "Kautek et al," Femtosecond puise laser ablation of metal lie, semiconducting, ceramic, and biological materials, "SPIE vol. 2207 , pp. 600-511, Apr. 1994 "and" Liu, X. et al. "Laser Ablation and Micromachining with Ultrashort Laser Puises", Oct. 1997, IEEE Journal of Quantum Electronics, vol. 33, No. 10, pp . 1706-1716 ". American patent USRE37585 describes a destruction process using a laser beam drawn from a material characterized by a ratio of fluence rupture threshold (F _rι ) / width of the laser beam (T) having an abrupt, rapid inflection , and clear or at least a clearly detectable and clear inflection of the slope for a predetermined value of the width of the laser beam.

The process of the present invention is particularly advantageous thanks to the use of particularly short pulse duration and particularly high powers. These extreme conditions allow precise machining of a wide variety of materials, with the same equipment. The power or duration of the pulses can however be adapted to the material, or to the speed and precision required for machining a portion of a workpiece.

The invention is thus based in particular on the observation that the use of extremely high powers, clearly greater than the powers used in conventional laser machining processes, allows almost instantaneous, explosive sublimation of the area irradiated by the laser beam. Despite the small size of this area, machining is therefore relatively rapid. Furthermore, by interrupting the light pulse after a very short time, the ablation is limited to the directly irradiated area, without touching the neighboring portions. The high powers used thus allow an extremely clean cut, with steep edges, to be obtained.

The invention is also based on the observation that the femto-laser is suitable for the machining of new types of parts and new materials, in particular small and high-precision parts, in particular watchmaking organs for which the femto-laser hadn't been suggested before. The invention also relates to such organs manufactured with the femto-laser and thus having dimensions, precisions and surface conditions previously considered almost unattainable. The method of the invention thus makes it possible to machine parts whose dimension is less than or equal to two millimeters, or preferably less than one millimeter, this dimension being counted "overall" and defined as the length of the segment which connects the two most distant parts of an organ part in the same direction. The method also makes it possible to machine parts comprising teeth whose depth is less than two millimeters, or even less than 0.5 millimeters.

The part is preferably supported by a micro-manipulator ensuring the positioning and orientation of the surface to be treated relative to the orientation of the laser beam. The workpiece can be supported by a multiaxial system controlled by a micrometric or even nanometric robot machining program with compensation or backlash. The movement of the workpiece, small and very light, can generally be carried out much more quickly and with a greater accuracy and reproducibility than moving the laser or associated optics. However, it is also possible to move the laser simultaneously, or even only, or to deflect the beam.

The ablation zone can thus be modified by translations of the workpiece at least in one plane (X and Y axes), by rotations in this plane along the C axis, and preferably also by translations along a Z axis perpendicular to the plane and / or by rotations along two perpendicular axes A and B. As indicated, displacements of the laser, or of the associated optics, can also be imagined. In addition, the focal distance can also be controlled in a direction parallel to the Z axis. The movements are controlled by machining software which receives data corresponding to a description of the shape to be machined. The description is given in mathematical form and the machining software determines the paths that the laser beam must travel, continuously or in steps, to generate these shapes. The invention is based on a geometric description using families of new curves, and taking into account the possibilities of femto-lasers to produce an ablation only at the focal point, at a precise distance from the laser. The ablation conditions can be optimized as a function of the material and of the machining depth, which can be modified for example by defining the angles of incidence of the laser beam and the positioning of the member to be machined relative to the beam. laser. Advantageously, the method also includes the steps of describing the shapes of the workpiece from the defined geometry using a 2D, 2D and a half or preferably 3D CAD representation, transfer of data from CAD on machining software, preferably three-dimensional, which preferably allows interpolations of left surfaces, definition of the steps as a function of the material and the machining depth so that the ablation conditions are optimized , - introduction of data into the computer for controlling and / or steering movements, positioning, in one direction, of the focal area by lighting using an optical head, whether or not equipped with a diffraction device , - positioning of the workpiece on the plane, clamping of the workpiece using clamping means, adjustment of the laser with ultra-short pulses, start of the machining program and machining of the c omposing by femto-laser with ultra-short pulses. According to an advantageous variant, the method according to the invention is carried out under a controlled atmosphere in order to avoid the appearance of non-linear phenomena generated at the light / material interface, for example the breakdown of air or the modification of the physicochemical properties of the medium.

The invention also relates to the parts produced by the method. The invention also results from the observation that machining by femto-laser ablation is suitable for the manufacture of very diverse parts, in particular parts and members having very small dimensions and having to be manufactured with a very fine resolution, which could not be manufactured in the prior art, or only with significant difficulties. The invention thus relates in particular to transmission members, in particular small members for watchmaking applications for example, manufactured according to the method. The invention also results from the observation that femto-laser machining is perfectly suited to the machining of pulleys and transmission belts in synthetic or composite material, with very small dimensions adapted to watchmaking, or of molds intended for injection or molding of such belts and pulleys. Advantageously, at least one of the dimensions of the workpiece according to the invention is less than two millimeters and advantageously less than 0.5 millimeters. The method is also suitable for machining parts that have at least one irregular or left surface characterized, among other things, by at least one radius located in the plane of curvature whose value is greater than 10 ^"9 m and less than 10 ^"3 m, preferably less than 10 ^{" 5} m.

Brief description of the drawings

Examples of implementation of the invention are indicated in the description illustrated by the appended figures in which: FIG. 1 represents, by way of example, a device for manufacturing parts according to the method of the invention, suitable for machining synchronous / asynchronous transmissions, FIG. 2 represents a synchronous / asynchronous transmission constituted here by an assembly said pulleys-belts with parallel strands, FIG. 3 represents a profile of curvilinear toothing, FIG. 4 represents two examples of asynchronous transmission with secondary pulleys disposed inside respectively outside the transmission, - FIG. 5 represents a sectional view of a laminated belt.

Device for implementing the invention

FIG. 1 illustrates a device for manufacturing a part 10, here a synchronous or asynchronous transmission for transmitting movements or power, and comprising: a work surface 11 having in this example 6 axes (A, B, C , Z,

Y, Z) programmable and clamping means 12 (for example systems such as flanges, adhesive, magnets, vacuum, etc.). The axes are controlled by a micrometric robot machining program executed by the computer 17, with play compensation or compensation means, a computer 13 having in particular a three-dimensional modeling software such as for example 3D CAD, a laser with ultra-short pulses 14 of the femto type comprising an optical head 15 allowing the emission of a beam 16 concentrated on a focal area (D), a computer for control / pilot of displacements 17.

Machining process The computer 13 can be constituted for example by a personal computer or a work station, and makes it possible to execute software making it possible to generate and store a three-dimensional model of the part to be machined, then to generate a machining program with from this three-dimensional model.

The machining program includes a series of instructions for moving the axes of the device, so as to move the focal area of the femtolaser along a three-dimensional trajectory allowing the machining of the part. The generation of the trajectory is based on interpolations, and the size of the indexing steps is a function in particular of the speed, the precision and the surface condition required. The machining program can be determined once and applied to the machining of multiple identical parts.

The control / pilot computer 17 executes the machining program and can be constituted for example by a numerical control or an industrial PC making it possible to control motors or actuators of axes to control the translations and rotations of the axes of movement of the laser 14, associated optics and / or the workpiece, so as to modify the relative position of the irradiated area D of the workpiece 10. The computer 17 thus sends orders to the attention of a power servo composed of variators and electric actuators which generate the movements of the axes with the required precision and speed.

The combination of rotations and translations along the six axes (A, B, C, X, Y, Z) of space allows the machining of practically any part 10, even a complex one.

A method of manufacturing a part 10, for example of a synchronous / asynchronous transmission by micro-belt, comprises in particular for example the following steps: description of the shapes to be machined, for example from the geometry defined on a 3D CAD plane, using computer 13, transfer of data to three-dimensional machining software taking into account in particular the interpolations of the left surfaces, and executed by data processing 13 or by data processing 17, definition of the steps (distance of displacement of the ablation zone between each pulse) according to the material and the depth of machining so that the conditions d ablation be optimized.

- introduction of data into the computer 17 which controls and controls the movements. The transfer of data between the data processing units 13 and 17 can be carried out by a network, for example of the LAN or Internet type, or via a magnetic, optical or electronic data medium.

- positioning, in the Z direction, of the focal zone D by lighting using optics 15, whether or not equipped with a diffraction device, positioning and rotation in the plane E (defined by the axes X and Y ) of the workpiece 10,

- fixing the workpiece 10 using the clamping means 12, to position and hold the workpiece, setting the laser to ultra-short femto pulses, with pulses of duration depending on the material, but preferably less at 500 fs (5χ10 ^'13 seconds), and of intensity depending on the material, start of the machining program and machining of part 10 by femto-laser. The machining program involves generation a succession of laser pulses along a continuous or discontinuous trajectory traversed by the irradiation zone, so as to cause the ablation of the irradiated zones. The trajectory of the ablation zone, and therefore the shapes to be machined, is described from the geometry defined on a 3D CAD plane. A time step is defined according to the material and the machining depth so that the ablation conditions are optimized.

Comparative experiments indicate that the fact of passing from 100 to 10 fs appreciably improves the machining precision. The fluences used in micromachining conventionally vary from 0.2 to 50 J / cm ² depending on the quality and speed of machining desired, preferably less than 10 μm per pulse, and typically at least from 0.5 to 0.25 μm / pulse depending on machined materials. The ablation precision is significantly improved compared to conventional lasers of the pico second or excimer type. The ultra-short pulse laser does not diffuse heat outside the irradiated volume, regardless of the material machined. The athermal nature of the process is due to the brevity of the pulses combined with a very high intensity of the order of 10 ¹ Λ att / cm ² at the focal plane of the beam. The current trend directs tools towards pulses of 100 fs (1.0 x 10 ^"13 seconds) for an energy of the order of MJ / pulse.

Physically, the electrons undergo a heating by phenomenon of the type "reverse Bremsstrahlung". The ejected electrons transmit their energy to the other electrons of the atomic network by shocks and cause an ionizing avalanche which causes an expulsion of matter. The transfer of energy from the electrons to the atom network of the machined material takes place in a period of time approximately 1000 times slower than the duration of a pulse. The ablation of material thus takes place even before there is thermal diffusion outside the irradiated zone.

The energy gradient of the laser beam is preferably determined so that only the intensity of a central zone whose cross section is less than 50% of the total cross section of the beam is greater than the threshold ablation of the material. The machining resolution is therefore less than the maximum beam diameter.

In a variant, two perfectly synchronized and non-parallel femto-laser beams are used. The intensity of each laser is below the ablation threshold of the material, which is machined only at the point of intersection of the two lasers. It is thus possible to machine hollow parts.

The intensity of the pulses, or their duration, can preferably be adapted by the computer control means 17, depending on the material to be machined and the requirements of precision and speed. It is also possible to modify these parameters during a machining cycle for the same part.

Generally, the relative movement between the laser beam and the workpiece is based on the spatial manipulation of the workpiece support. It should be noted in the method of the invention that for particular cases, the beam may, independently of the movements of the part to be ablated, at the exit of the optical head, be deflected by means of different optical systems mirrors, scanner, telescope ... A displacement of the laser is also possible, but its inertia risks making its movements slower to stabilize than those of the part.

Most of the shapes machined on the elements used to make the transmissions 10 or any other micro- or nano-component can be machined in a plane. In the case of machining more complex surfaces such as complex teeth (not shown), the beam impact point 16 of the laser can be moved along 3 axes simultaneously, or even 4 axes with a rotating plane 11 and a head pivoting optics.

The speed of movement of the part results from a compromise depending on the desired production rate, precision or resolution required, and the desired ace status. Many parts will therefore be machined by a variable speed displacement sequence.

In order to avoid the appearance of non-linear phenomena resulting from the light / matter interface, it will be possible to machine under vacuum or under projection of neutral gas (helium, argon, etc.). Machining in a controlled atmosphere makes it possible to avoid non-linear phenomena produced within the light-matter interface, such as for example the breakdown of air at the focal plane and the corollary appearance of instability altering the quality of 'machining. In the case of specific applications, in order to improve the energy efficiency of ablation, optical precision can be improved by adopting a diffraction or optical servo system mounted in addition to the focusing device.

Geometric representation of the workpieces; displacements of the irradiation zone The most common displacements which can be carried out by the irradiation zone of the part are: a) rapid positioning, which requires the moving parts to reach the programmed point by performing a linear trajectory, at the maximum speed allowed by the machine, b) linear interpolation, which makes it possible to reach the programmed point by traversing a linear trajectory at the speed of advance specified by the programmer, c) circular interpolation, which has for function of describing complete circles or arcs of a circle from certain characteristic geometric elements which define them, such as the coordinates of the center and those of the extreme points for example. d) helical interpolation, which combines a circular movement in a plane with a translational movement perpendicular to this plane, e) conical interpolation in the plane, where each parabolic segment is geometrically defined by a group of 3 points, the last point of a segment must be the first of the following segment, f) polynomial interpolation, which allows the definition of trajectories from polynomials and which is used for smoothing spline curves.

In the case of the manufacture of micro-transmissions, for example belts, most of the shapes can be machined in a plane. To do this, we use 2D or 2D1 / 2 machining techniques. The following machining operations can be carried out using the method and device of the invention: a) contouring (mode in which the tool remains positioned at a constant depth while it describes, in the plane, a series lines and curves), b) drilling and its related operations c) machining of negative volumes.

In the case of machining more complex surfaces such as the teeth or the left surfaces, the laser beam is moved along three axes simultaneously, or even more with a rotating plate and an optical head that can be pivoted. It is also possible to pivot the optical head on two axes (twist head) on a swivel plate. Finally, it is also possible to move the focal length parallel to the Z axis. The machining method of the invention is particularly advantageous in that the permitted geometries are not limited to straight line segments (simple interpolation) or to circles. Furthermore, it is common, in particular in the conventional machining techniques used in watchmaking, to meet spoils or connections determined in a more or less vague or even implicit manner (geometry resulting from the intersection of two surfaces imposed by the shape of the tools). Obviously, these conventional methods are not suitable for the machining of complex shapes, notably left, and more generally for all operations where precise control of surface intersections (connecting leave) is required.

In order to allow machining by ablation of material, in all possible cases, we can define the shapes or surfaces to be treated using mathematical principles using geometry and algorithms (graphs, algorithmic geometry, probabi list algorithms ...)

Conventionally, the geometric representation of the complex surfaces generated by the ablation process of matter by means of an ultra-short pulse laser calls for the definition of special curves known as pole curves. The most common representation method is that which uses Bézier curves. There is also an evolution known as B-spline curves.

For the more complex forms and in particular for those which enter into the definition of the curvilinear profiles for which the conics are necessary (arcs of circles, ellipses, parabolas, etc.) we use the rational curves where the representation of the conics is generated by a quotient of polynomials and not by an integral polynomial parametric equation. The most common rational curves, namely the rational Bézier curves defined by polynomials where a surface is decomposed into simple elements called meshes themselves defined by points called poles, or the "spline" curves and NURBS (Non-Uniform Rational B-Spline) which are defined by sets of points forming surface tiles in a network, can be used for defining the surfaces to be machined.

These families of curves can be explained more precisely: - Bézier curves: these are parametric curves calling in particular on the following notions: Bernstein polynomials, De Casteljau evaluation algorithm, subdivision, rise in degree, derivation , geometric properties (affine invariance, convex envelope, decrease in variation), - B-spline functions: defined as the basis of P (k, t, r), multiplicities of nodes, class C ^raccord k fitting, local and minimal supports , B-spline curves in the form of parametric B-splines calling on the notions of control polygon, De Boor's evaluation algorithm, and in particular having geometric properties such as for example the affine invariance, local control, l convex envelope, multiple nodes at the edge, insertion of nodes, * geometric spline curves which respond to the concept of geometric continuity, geometric invariants, as well as the known forms Frenet frame, nu-splines, tau-splines. The machining process by ablation of material using an ultra-short pulse laser differs from other machining processes in that it uses without distinction, depending on the precision or complexity of machining required, data algorithms based, without this list being exhaustive, on the following mathematical principles: - curvature, torsion, Frenet benchmark, Jordan's theorem, isoperimetric inequality, envelopes or focal curves, surfaces and hypersurfaces like the two fundamental forms of a surface and in particular curvatures, Gauss-Bonnet formula, intrinsic geometry, parallel transport, geodesics, Morse theory allowing to link the type of homotopy of a variety to the critical points of a generic function with certain good properties, including in the demonstration of the Gauss-Bonnet formula, also mast the Hessian, the critical points and the Morse lemma, functions defined on a surface such as height and distance functions, vector fields and Morse diagram, in particular the techniques used in reconstruction theories, elements of combinatorial and algebraic topology and in particular: triangulations, simplicial complexes, Euler-Poincaré characteristic, varieties, surface classification theorem, elements of differential geometry: geometry surfaces in R ³ : Gauss application, curvatures and direct main ions, classification of points (elliptical, hyperbolic, parabolic, plane), focal surfaces, geodesics,

- Euclidean quadrants and osculating quadrics with smooth surface, skeletons in the aspect of plane curves, evolves, skeletonization, as well as their geometric criteria (distance to the skeleton, differentiability of the distance, ridges and ravines functions) and their topological properties (homotopies and retracts )

- references to the Voronoi diagram, Delaunay triangulations in 2D, and skeleton approximation, reconstruction and mesh of surfaces taking into account in particular the limited Delaunay triangulation, the nerve theorem of homotopies and homeomorphisms but also criteria for sampling curves and surf aces, - surface refinement algorithms, algorithmic geometry and in particular intersections of segments, the calculation of convex envelopes in 2 and nD, property of duality, linear programming, geometric data structures, complex or not, using deterministic and probabi lists algorithms, - use of interpolation and smoothing algorithms as well than cross validation relating to the choice of smoothing parameters and in particular without this list being exhaustive

• smoothing by least squares (taking into account weights and constraints), ^• interpolation by polynomial splines spline spaces, minimization of an energy, algorithm for calculating the interpolation spline, spline bases (S-spline),

^• smoothing by spline: smoothing splines, calculation algorithms, cross validation methods during the choice of the smoothing parameter.

The ablation process described in the present invention makes extensive use of algorithms using the technique of NURBS (Non Uniform Rational Basic Splines).

We define these NURBS as a set of techniques used for interpolation and approximation of curves and surfaces. These techniques are very present in formal computing systems and digital and taken up by the main geometric modeling software such as CAD or CAD / CAM tools.

These functions are defined on the basis of real values called nodes which correspond to the uniform case. They have a given degree which is for the classic forms that we machine 2 or 3 and rarely more. Their value is between O and 1 but not zero only over an interval.

The function described is all the smoother the higher its degree: - degree 1 = continuous function, degree 2 = differentiable function (no angular points), degree 3 = twice differentiable (no breaking of curvature),

When we modify a node the function is continuously deformed.

When two nodes coincide (the node becomes double) there is a loss of continuity with either a discontinuity, an angular point, or a break in curvature.

The order of continuity at a node is equal to the degree minus the multiplicity of the node, for example

B-spline of degree 2, single node -> differentiability,

B-spline of degree 2, double knot -> angular point,

B-spline of degree 2 triple node - discontinuity In the case of curves defined by control points (for example tooth profile) we give ourselves points of the plane (called control points) and a set of values (called vector of the nodes). We can cite fundamental properties 1) The curve is entirely contained in the convex envelope (because the coefficients of the combination of are between 0 and 1 with a sum equal to 1).

2) This definition does not depend on the dimension, one can thus use it as well in the plane as in the space in 3 dimensions, and even beyond.

3) The curve only depends on the relative position of the nodes; if we make a translation or a homothety the curve is unchanged; the nodes (0,0,1,2,4,4,4) will give the same curve as (-1, -1,1,3,7,7,7). 4) When a basic function is worth 1, the others are null and the curve passes by the control point which is associated in particular with it, when the first (respectively the last) node is of multiplicity, the first (respectively the last ) basic function y is worth 1 and the curve passes by the first (respectively the last) point there is a curve known as with floating ends of which the Bézier curves are a particular case.

Finally, it is interesting to define the role of homogeneous coordinates forming rational curves.

Finally, it will be noted that the mathematical method described above is the only one which can guarantee the factors of homothety useful for the proper use of the theory of mechanisms applied to micro- and nano-mechanisms (compliance with the conditions of sliding, friction, meshing. ...). Parts and components which can be produced with the process of the invention

The machining by femto-laser ablation is suitable for the manufacture of parts and organs comprising reduced dimensions and having to be manufactured with a very fine resolution, in particular but not exclusively in the horological field. This process is particularly suitable when at least one of the dimensions of the part, in at least one direction, is less than or equal to 2 millimeters. The dimensions are counted "overall" and defined as the measure of the segment which connects the two most distant points of the same part in the same direction. More generally, this process is suitable for the manufacture of all micro- and nano-mechanical elements, the definition of which docking radii (intersection of two surfaces) impose precise dimensional conditions in millimeters.

The method of the invention is thus for example suitable for the manufacture of transmission members, in particular small members for horological applications for example.

The manufactured parts can comprise at least one curvilinear line, often irregular, formed in a perpendicular plane, at least of a radius greater than 10 ^"9 m and less than 2 mm. An example can be given by the observation of the edges which mark the intersection of two surfaces produced by any kind of machining. At the macroscopic level (scale of a few millimeters, 10 ^"3 m) these edges can be assumed to be rectilinear or circular and formed by salient or obtuse angles. However, at the microscopic level these same lines are characterized, in the plane perpendicular to the edge line, by a geometry, more or less regular, comprising at least one radius, often called connecting fillet, of a few tenths of a millimeter at most .

The method of the invention is particularly suitable for the machining, in whole or in part, of the following watch parts: the body of a watch, and in particular the plate comprising recesses and holes serving as support frame, bridges of right or left shapes serving to hold in place or guide in rotation or in displacement of the various components of a micro mechanism , the material connections between solids, and in particular embedding, slide, simple or sliding pivot, translation and rotation, helical, plane support, simple ball joint or finger, linear annular, linear rectilinear, punctual ..., the energy accumulating organs , in particular springs, and barrel components, micro- or nano-transmission devices by right or left gears, pulleys, friction wheels, rigid or flexible constant velocity connections, hydrostatic and hydrodynamic elements, pivot or slide links, mechanical storage devices, in particular cams, components linked to the exhaust function and in particular those s for the distribution of energy, in particular detent systems, cylinder, English anchor, pin, meeting wheel, etc., in particular the following elements: escape wheel, escape tooth, twill, arm, hub, anchor, rod, entry or exit pallet or lift, fork, entry or exit horn, sting, limiting, entry or exit pin, large and small plate, balance wheel, oscillating members, so-called regulation, whether of the family of pendulums or balance-springs, and, in a more general, all the vibrating systems according to modes damped or not, linear or not, including or not mechanical or viscomechanical damping devices, including the following adjacent elements: cock, pendulum, ferrule, piton, piton holder, racket, hairspring flat, spiral coming from complex helicoids with left or right unwinding, the elements linked to the rotating regulation systems and in particular without this restricting the vortices or the carousels, the oscillating masses whether they are of revolution, linear or pivoting , - the striking devices, the covering elements, such as in particular glass, bezel, middle, crown, correctors, dial, hands, casing circle, case back, bars, bracelets and their components, pushers, display cell , crowns, display symbols such as simple or perpetual date indicators, date indicator, moon phase indicators, cadra applique n, the boxes, whether made in one or more pieces, with or without elements such as: winder, crown, pushers ...

Transmission manufacturing with belts

As indicated, the process of the invention is also suitable for the production of synchronous or asynchronous transmissions, in particular micro- and nano-transmissions, for example pulleys, smooth or toothed belts, chains, spur gears or left, constant velocity transmission elements, etc. Such transmissions are used for example in watchmaking or in other miniaturized devices. We will therefore describe in more detail some examples of transmission which can be machined with this process. In one embodiment, the movement / power transmissions by belts manufactured with the method of the invention are asynchronous and consist of at least one wheel, a flat or trapezoidal or ribbed belt, and preferably have d '' at least one tension and / or guide roller which is located inside or outside the micro-belt. Asynchronism stems from the possibility of the belts sliding on the pulleys under the action of too much torque.

Furthermore, the transmissions by asynchronous micro-belts can be mounted on pivot or slide links which allows to increase the winding angle on the pulleys, or to ensure clutch / declutching functions.

Synchronous micro-transmissions by belts consist of at least two toothed wheels and a toothed belt of the same module, which has the effect of allowing the transmission of mechanical power between a motor element and a receiving element without sliding, thus correcting the problem posed by the functional or accidental slip of asynchronous transmissions, in particular in the event of overload. We consider here the mechanical micro- or nano-chain as being a particular form of the toothed belt since it itself has notches coming to mesh on teeth.

Synchronous movement / power transmissions by toothed belts include in particular: a load-bearing geometry with controlled deformation (elastic range of the material), toothing with a curvilinear or polygonal profile, ortho-radial, straight, inclined or curvilinear toothing placed on the plane carrier. The components of a movement / power transmission produced according to the present invention are made of material having sufficient mechanical characteristics to ensure the transmission function, for example plastic, polymer, metal, composite, sandwich structure, etc.

The transmission members of the process can comprise, for example pulleys and belts that are smooth or with teeth spaced apart at a pitch of less than two millimeters, for example micro-belts or wheels whose teeth are of the order of 0.5 μm, as well as belts whose depth or width of the teeth is less than two millimeters. The thickness or width of the belt itself is preferably also less than two millimeters. The limits of machining precision are linked to the beam offset. Such members, in particular such belts and pulleys, are for example intended to be used in a watch movement, other watch movement components, or other parts of micromechanics.

By way of example, FIG. 2 illustrates a synchronous movement / power transmission 10 by belt manufactured entirely, or in part, with the method of the invention. The assembly includes in particular a main pulley 23, a belt 20, a secondary pulley 22 and a tensioning roller 21. The pulley 23 is flat and provided on the periphery with equidistant radial teeth comparable to a flat gear wheel. The pulley 23 is provided with a flange (not shown) in order to guide the belt 20. It is possible to manufacture all of the components of this transmission, or only a part, with the femto-laser ablation process of the 'invention.

The belts 20 preferably have curvilinear tooth profiles 30 illustrated in FIG. 3. This curvilinear profile allows efficient power transmission even when the radius of curvature of the belt varies significantly, for example when the belt works with pulleys of very different diameters. A curved tooth profile can also be adopted for the pulleys.

When performing a synchronous transmission, the flanges (not shown) are arranged on a single pulley 23, preferably on the one with the smallest diameter.

FIG. 4 illustrates two examples of asynchronous transmission 10 with secondary pulleys 22 inside / outside and where the asynchronous pulley 23 is flat and provided with flanges (not shown) on either side of said pulley 23 in order to guide the belt 20 on said transmission 10.

The present invention allows the use of complex materials without sizing limitation as well as the production of structures of the sandwich or composite type, in particular for belts. FIG. 5 illustrates an example of laminated belts 50 with several layers 51.

It should be noted that in the case of embodiments of pulleys 23 or micrometric or nanometric organs of small dimensions with / without curvilinear profiles 30, no rule is imposed; we will talk about personalized profiles. In addition, for each type of toothing profile there are teeth with straight sides or involutes (not shown).

Gear manufacturing

The invention also relates to the manufacture of millimetric or nanometric gears, a gear being considered here as the element used in the composition of a synchronous transmission ensuring the connection between two shafts and transmitting mechanical power from a driving shaft (motor ) to a driven shaft (receiver) while maintaining a constant ratio of angular velocities.

Different forms of gears can be considered: The elementary shape is called "external parallel" and is characterized, in addition to the absence of relative sliding of the two meshed wheels, by a ratio of angular speeds equal to the inverse ratio of the numbers of teeth or diameters and by a relative rotation of the wheels in the opposite direction. A variant exists in a form called "internal parallel" where the two wheels rotate in the same direction. This described shape, parallel, exterior, or interior, with straight teeth, is also characterized by a pitch, a module and a transmission ratio. The geometry of the teeth is described symmetrically in the meshing plane according to a curvilinear profile.

A more elaborate shape meets the criteria of helical toothing defined by a "regulated surface" generated by an infinity of tangents to the basic helix. It can also be defined as the surface generated by an involute moving along the helix. The particular shape called "rack and pinion" is characterized in that the rack is a particular wheel whose primitive line is a straight line, it can from a geometric point of view be seen as a wheel of infinite diameter. -

It is possible to transpose the helical teeth to the rack and pinion kinematics. It should be ensured that when the two primitive cylinders of the gear rotate without slipping, the two primitive conjugate propellers remain constantly tangent which implies two conditions: the two propellers must be in opposite directions, namely that a wheel with left can only form a parallel gear with a pinion on the right; it is necessary to respect the geometrical conditions related to the gear (meshing conditions).

The method of the invention also allows the production of concurrent gears. In the first place, we must consider the straight shape in which the primitive surfaces are two cones with the same apex which roll without sliding over each other. The teeth are straight or spirals. In the particular case of concurrent gears, it is necessary to pay attention to the problems of mesh continuity and interference by the so-called complementary gear method. This approach makes it possible to study the meshing in the concurrent gear, with a sufficient approximation by simply considering a parallel gear. Thus all the questions relating to the continuity of meshing, to the interferences, to the relative sliding, are treated by considering the parallel gear according to its angular speeds, the numbers of teeth, the modulus and the angle of pressure. The present invention also allows the manufacture of left gears, for example a wheel collaborating with a worm. The worm gear meshes with its wheel combined with a given center distance. In the prior art, the wheel is usually cut with a tool corresponding exactly to the worm with which it must mesh (envelope method). The use of an ultra-short pulse laser relieves this constraint of small dimensions which also remained impracticable by conventional methods. In this kind of gear, particular attention will be paid to relative sliding as well as to the notion of reversibility. '' The elaborate shape dealing with left helical gears in particular because of the punctual contact between teeth makes operation under low loads particularly effective for very small movements.

The complex shape called the hypoid gear will also be taken into account in particular in that the ablation process allows a size with very small dimensions, which is excluded by any other known method.

Regardless of the shape and size of the gears, it is essential to observe during design the interference conditions and in particular that related to asymmetrical shapes and machining conditions. The descriptive methods mentioned for the generation of curves and these left surfaces ensures control of geometric interference. In addition, the laser ablation technique using ultra-short pulses makes it possible to control machining interference. The two aspects being combined, the present invention offers a relevant response to the definition, manufacture and control of interference for micro and nano transmission, this independently of the forms of toothing or the materials used.

Manufacture of micro-molds In the prior art, pulleys, toothed wheels and tension rollers are produced by traditional methods such as turning and / or milling, electroerosion, ultrasonic machining, etc. The traditional belts are produced in particular by molding, the molds being produced by electroerosion, ultrasound or even by the LIGA process (Lithography, Galvanisierung, Abformung).

These methods are suitable for making micro molds whose dimensions go beyond a millimeter. They impose the use of injectable plastics, and are ill-suited to the manufacture of parts using materials such as metals, composites or even heterogeneous multilayers for example. Temperature or dynamic viscosity constraints limit the use of such micromoulds, even for the production of parts made of synthetic materials.

Even when they can be implemented, the techniques of the prior art require the manufacture of molds with sufficient precision. The present invention therefore also relates to micromoulds used for the manufacture of transmissions or transmission elements injected or with structures of the sandwich or composite type. For example, the multi-layer laminated belt of FIG. 5 can thus advantageously, depending on the dimensions, be manufactured by molding or injection in a micro-mold machined with the method of the invention. In general, the molds machined by the process described in the invention, whatever their type, use a certain number of functional sub-assemblies, the molding elements: imprint (punch and die) - the functional elements: carcass, feed, release and demoulding mechanisms for injected parts, mold temperature regulation devices, auxiliary elements: fixing and handling device, centering systems, robots for placing prisoners and extracting molded parts , security and release control devices.

The laser machining process with ultra-short pulses is suitable for producing an cavity in the impression in which the negative three-dimensional representation of the object (all dimensional corrections included) is limited by the two parts that are the punch and the die.

This process allows any micro- or nano-molded part to be produced as long as the art of molding is preserved and the viscosities of the materials used allow it (very small dimensions). The surface conditions obtained are excellent, which is important in particular for rubbing parts.

Machinable materials

Depending on the workpiece, the method of the invention can be used for machining a large number of different materials. It is particularly suitable for the machining of isotropic, polymorphic (for example lamella ...) or hard composites, in particular plastics, metals, minerals or composites. By plastic we mean any material containing an essential ingredient "high polymer", definition given in standards ISO 472 and ISO 472 (January 2002). By "high polymer" or more generally "polymer" means a product consisting of molecules characterized by a large number of repetitions of one or more species of atoms or groups of atoms (constitutional units), linked in sufficient quantity to lead to a set of properties which practically do not vary with the addition or elimination of a single or a small number of constitutional grounds (ISO 472). It is also a product made up of high molecular weight polymer molecules (ISO 472).

The following plastic and / or polymer materials can in particular be machined with the process of the invention:

- Polyolefins, for example polyethylene PE, polypropylene PP, polyisobutylene P-IB, polymethylpentene P-MP polyvinyl chlorides and their derivatives (PVC) according to ISO 1043-1 / 458-2 / 4575/1264 1060-2 / 2898-1, 6401, and in particular superchlorinated polyvinyl chloride PVCC, polyvinylidene chloride PVDC, copolymers, vinyl chloride and propylene VC / P, mixtures of vinyl chloride and chlorinated polyethylene PVC / E, mixtures of vinyl chloride and PVOABS styrene acrylo-butadiene, vinyl chloride and PVC / A acrylate graft copolymers, PVOAC vinyl chloride / vinyl acetate copolymers

Polyvinyl acetates and their PVAC derivatives and in particular polyvinyl acetate PVAC, polyvinyl alcohol PVAL, polybutyral vinyl PVB, polyformal vinyl PVFM

The styrenics according to the ISO 1043-1 / 2580-1 / 2897-1 / 4894-1 / 6402-1 standards, in particular impact polystyrene SB, acrylonitrile polystyrene SAN, acrylobutadiene styrene ABS, acrylonitrile styrene acrylate ASA, polystyrene-maleic anhydride modified elastomer mSMA, mixtures based on PS and in particular PC ABS, ABS / PA, PS / Polyphenylene ether PPE, PS / PP and PS / PE, polyacrylics (PMMA) according to ISO 7823-1 / 7823-2 / 8257-1, polyacrylonitrile PAN, copolymer A / MMA acrylonitrile / methyl methacrylate, acrylonitrile / butadiene copolymer, styrene / acrylonitrile copolymer SAN, acrylonitrile / butadiene / styrene ABS copolymer, methyl methacrylate / acrylonitrile.butadiene / styrene MBS copolymer, etc.

PMMA / AES mixtures or alloys

Saturated polyesters - Polyalkylene Terephthalates PET and PBT according to ISO 1043-1 / 1628-5 / 7792-1, Polyamides (PA) according to ISO 1043-1 / 1874-1 / 599 / 3451-4 /

7628-1 / 7628-2 / 7375-1 / 7375-2, in particular PA 6.6, PA 6.10, PA 6.12, PA 4.6, PA 6, PA 11, PA 12, etc. polyoxy methylenes (POM) according to ISO 1043-1, fluorinated polymers according to ISO 1043-1, polytetrafluoroethylene PTFE, polychlorotrifluoroetylene PCTFE, polyvinylidene fluoride PVDF, polychlorotrifluoroetylene PCTFE, poly (ethylene-propylene) perfluorinated FEP, ethylene copolymer PTFE ETFE, cellulosics according to ISO 1043-1, cellulose nitrate or nitrocellulose CN, ethylcellulose EC and methyl cellulose HC, cellulose acetate CA and cellulose triacetate CTA

Polymers with an aromatic skeleton according to ISO 1043-1, in particular polycarbonate PC according to ISO 1043-1 / 1628-4 / 7391-1 / 7391-2, phenylene polysulphide PPS, polyphenylene ether PPE, poly-2-6 phenylene dimethyloxide, polyphenylene ether, polyaryletherketones PEEK, polyaryletherketoneoneetherketone

PAEK, polyetheretherketone PEEK, polyetherketone, aromatic polysulfone PSU, polyethersulfone PESU, polyphenylsulfone PPSU, aromatic polyamide, polyarylamides PAA, polyphthalamides PPA, semi-aromatic polyamides PA 6-3T, polyamide PA-imides , polyterephthalate bisphenol A (polyacrylate), polyetherimide PET, cellulose propionate CP and cellulose acetopropionate CAP, cellulose acetobutyrate CAB, liquid crystal polymers (Vectra ©, Sumika © and Zenite ©) LCP, thermoplastic elastomers according to ISO 1043-1, block copolymers of Hytrel © or Pebax © type, ionomers of Surlyn © type, ultrablend S © (BASF) PBT + ASA, cycoloy © (GB Plastics, Lastilac (Lati) PC + ABS, xénoy © (GE plastics) PC + PET, orgalloy © RS6000 (ATO) PA6 / PP, stapron © N (DSM) ABS / PA 6, lastiflex © AR-VO (Lati), PVC + terpolymers, etc. - Polyurethanes according to ISO 1043-1 in particular for obtaining cast elastomers, or thermoplastic or polyurethane-polyurea (thermosetting) or cellular polyurethanes, micro-cellular elastomers from the following compounds: PUR polyurethane, isocyanate + donor d , isocyanate, polyisocyanates and especially toluene diis TDI ocyanate, polyols (polyesters and polyethers), MDA and MOCA amines, SI silicones according to ISO 1043-1, silicon Si polysiloxane, PF phenoplasts and in particular PF2E1, PF2E1, PF2C1. PF2C3, PF2A1-2A2, PF1A-1A2, PF2D1, PF2D4, aminoplasts (MF, UP) according to ISO 4614 and 1043-1, melamine formaldehyde MF, urea formaldehyde UF, thermosetting unsaturated polyesters

In general, it will be noted that, when possible and desired, these materials can receive reinforcements, in particular using the following materials: aromatic polyamide (Kevlar © by Dupont de Nemours), glass in all its forms including silica-sodium forms, high modulus carbon, high resistance carbon, boron, steels, mica, wollastonite, calcium carbonate, talc, polytetrafluoroethylene (PTFE), for example Tef Ion ©, etc.

Furthermore, machined plastic products may or may not be covered with mineral, synthetic or metallic films. The process of the invention also applies to the machining of most pure metals and their alloys. Mention may in particular be made of solid metal alloys, steels and cast irons of copper, aluminum, nickel or chromium, molybdenum, tungsten or manganese, gold, platinum or silver, titanium or cobalt, boron or niobium, tantalum, as well as pure metals.

Many minerals, including quartz, can also be processed using this process. Finally, it is also suitable for the machining of composite materials, that is to say materials with an organic or metallic matrix / binder and comprising in particular, without being exhaustive, phenolics, polyesters, epoxides, polyimides, fiber reinforced / additive reinforcements (mainly celluloses, glass E, C, S, R ..., boron, etc.), whiskers (whiskers) AIO3, Si02, ZrO2, MgO, TiO2, BeO, SiC, low modulus aramid, high modulus aramid, high tenacity carbon, high modulus carbon, boron, steel, aluminum, etc., as well as materials loaded with mineral matter, in particular chalk, silica, kaolin, titanium oxide, glass ball, etc.

These composites can include additives, in particular catalysts or accelerators, and in the solid form can be in the form of a monolayer, laminate, sandwich, etc.

We cite more particularly the following composites without this being exhaustive: Aluminum / Copper - composite with a metal matrix Al 77.9 / SiC 17.8 / Cu 3.3, Mg1.2 / Mn 0.4; Aluminum / Lithium - composite ~ metallic matrix Al 81 / SiC 15 / Li 2 / Cu 1, 2 / Mg 0.8; Carbon / vinyl ester - carbon fiber - vinyl ester matrix; Carbon / polyaramide - carbon fiber - polyaramide fiber; Carbon / carbon composite - carbon fiber - carbon matrix; Carbon / epoxy composite - carbon fiber - epoxy matrix; Carbon composite / polyetheretherketone - carbon fiber - PEEK matrix; Polyaramide / vinyl ester composite - polyaramide fiber - vinyl ester matrix; Polyethylene / polyethylene composite - polyethylene fiber polyethylene matrix; E-glass / epoxy - borosilicate / epoxy glass; polyaramide / polyphenylene sulfide - polyaramide fiber - PPS matrix.

Finally, many ceramics can be machined with the process of the invention. Ceramics consist of natural raw materials polycrista Mines or polyphasées or synthetic sintered alumina, silica, silico-aluminous or silico-magnesian compounds (cordierite, mullite, steatite) and more generally oxynitride, sialon, carbide ... preferred materials are short monocrystalline fibers dispersed inside an organic, metallic or ceramic matrix. As well as metallic carbide whiskeys, as well as organometallic precursors like SiC or Si3N4 ... These materials can be implemented by dry pressing, thermoplastic injection, strip casting, etc.

The main ceramics, without being exhaustive, are given, alumina AI2O3, alumina / Silica AI2O3 80 / Si02 20, alumina / Silica AI2O3, 96 / SiO2 4 - Saff il®, alumina / Silica / Boron oxide AI2O3 70 / Si02 28 / B2O, 2, alumina / silica / Boron oxide AI2O3 62 / SiO2 24 / B20, 14, potassium aluminosilicate Muscovite Mica, Boron carbide B4C, silicon carbide SiC, silicon carbide - bonded by reaction SiC, silicon carbide - hot pressed SiC, carbide

Tungsten / Cobalt WC 94 / Co 6, machinable glass ceramic Si02 46 / AI203 16 / MgO 17 / K2O 10 / B2O3 7, permeable ceramic SiO2 50 / ZrSiC, 40 / AI203 10, Titanium diboride TiB2, dioxide Titanium TiO2 99.6%, Magnesium oxide MgO, Aluminum nitride AIN, Aluminum nitride - machinable Shapal-M®, Boron nitride BN, silicon nitride Si3N4, silicon nitride - bonded by reaction Si3N4, silicon nitride - hot pressed Si3N4, silicon nitride / Aluminum nitride / Alumina, sialon, Zinc oxide / Alumina ZnO 98 / AI2O3 2, Yttrium oxide Y203, Beryllium oxide BeO 99.5 quartz - Fused Si02, ruby AI2O3 / Cr2O3 / 5i203, sapphire AI2O3 99.9, Alumina silicate SiO2, 53 / AI2O3 47, silica SiO2 96, erre - alumina-silicate Si02 57 / AI203 36 / CaO / MgO / BaO, non-stabilized zirconia Zr02 99, zirconia - stabilized with Yttria ZrO2 / Y2O3, zirconia stabilized with Magnesia ZrO2 / MgO, etc. Thanks to the very localized heating of the material, the use of a laser with ultra-short pulses allows: in plastic materials a cutting without thermal damage of the cutting area in composite materials, direct cutting without delamination of the multilayer material, the machining of all metals without formation of sagging or burrs or even flaring at the incident surface.

List of elements in the figures

10 Machined part, for example transmission such as belt. 11 Work plan 12 Clamping means (fixing means) 13 Computing to execute three-dimensional modeling software 14 Femto laser 15 Optical head 16 Laser beam 17 Computing to execute the machining program X. Y, Z Translation axes of the workpiece A, B, C Rotation axes of the workpiece 20 Belt 21 Tension pulley 22 Secondary pulley 23 Main pulley 30 Curved toothing 50 Laminated belt 51 Reinforcement

Claims

claims

1. Method for manufacturing a micro- or nano-mechanical part, characterized by a laser ablation step using a pulse laser with a duration of less than 5x10 ^"13 seconds and with greater power at 10 ¹² watts on the beam-matter interaction surface.

2. The method of claim 1, implemented for the manufacture of parts intended for watchmaking.

3. The method of one of claims 1 or 2, implemented for the manufacture of pulleys and / or belts.

4. The method of one of claims 1 to 3, wherein at least one dimension of the part is less than or equal to two millimeters, or preferably less than 0.5 millimeter, this dimension being counted "overall" and defined as the length of the segment which connects the two most distant points of a part in the same direction.

5. The method of one of claims 1 to 4, wherein said part comprises teeth whose depth is less than two millimeters.

6. The method of one of claims 1 to 5, wherein said part is supported by a micro-manipulator ensuring the positioning and orientation of the surface to be treated relative to the orientation of the laser beam.

7. The method of one of claims 1 to 6, comprising the following steps: description of the shapes to be machined, transfer of data corresponding to said description on a machining software, said machining software preferably taking into account in particular the interpolations of the left surfaces, definition of the angles of incidence of the beam and the positioning of the workpiece in relation to the laser beam, depending on the material and the machining depth so that the ablation conditions are optimized, input of data into the displacement control / pilot computer (17) , setting the ultra-short pulse laser with a duration of less than 5x10 ^"13 seconds and a power greater than 10 ¹² watts on the beam-material interaction surface, start of the machining program and machining of the part (10) by pulse laser.

8. The method of one of claims 1 to 7, wherein the energy gradient of the laser beam is determined so that only the intensity of a central area whose section is less than 50% of the total section of the beam is greater than the ablation threshold of the material.

9. The method of one of claims 1 to 8, wherein the ablation is carried out only in the focal plane of the laser beam (16), the method comprising a step of moving said focal plane relative to said part in a direction perpendicular to said laser beam.

10. The method of one of claims 1 to 9, wherein said workpiece (10) is supported by a multiaxial system controlled by a machining program, for example a micrometric robot machining program with compensation or compensation of play.

11. The method of one of claims 1 to 10, in which the power and the duration of the pulses are chosen according to the material of the part so as to allow the ablation of a few μm of material, preferably less than 10 μm , per pulse.

12. The method of one of claims 1 to 11, in which the ablation is carried out under vacuum, under projection of neutral gas or under a controlled atmosphere in order to avoid the appearance of phenomena not linear which result from the light-matter interface such as air breakdown or material alteration.

13. The method of one of claims 1 to 12, using a laser beam diffraction device.

14. The method of one of claims 1 to 13, involving a step of positioning said part (10) in a plane (E).

15. The method of one of claims 1 to 14, said organ part comprising at least one of the following components: plastic, metal, composite, ceramic, mineral material, organic complex matrix material, hard isotropic material.

16. The method of one of claims 7 to 15, wherein said description of the shapes to be machined is carried out from the geometry defined on a 3D CAD plane, machining steps being defined as a function of the material and of the machining depth so that the ablation conditions are optimized, the focal zone being positioned by lighting using an optical head (15) with or without a diffraction device.

17. Body manufactured according to the method of one of claims 1 to 16.

18. The member of claim 17, characterized in that at least one of its dimensions is less than or equal to two millimeters, or preferably less than 0.5 millimeters, this dimension being counted "overall" and defined as the length of the segment which connects the two most distant points of a part in the same direction.

19. The member of claim 18, characterized in that it comprises teeth spaced at a pitch of less than two millimeters and / or whose depth is less than two millimeters.

20. The member of one of claims 17 to 19, characterized in that it has at least one curvilinear line, for example an irregular curvilinear line, formed in a plane perpendicular to the plane of the organ, at least d 'a radius greater than 10 ^{' 9} m and less than 5 millimeters.

21. The member of one of claims 17 to 20, being intended for a horological application.

22. The organ of claim 21, constituted by a synchronous or asynchronous transmission. 23. The member of claim 22, consisting of a belt

(20) and / or by a pulley (22,

23).

24. The member of claim 23, wherein said belt has a thickness or width less than two millimeters.

25. The component of claim 21, consisting of one of the following elements: an element of a watch exhaust system; an element of a watch regulation system; or an element of the kinematic chain of transmission of energy and movements between the energy source and the needles of a watch.

26. The member of claim 25, the largest dimension of which is less than a millimeter.

27. The member of one of claims 18 or 19, being intended for application outside of watchmaking.

28. The member of one of claims 17 to 27, consisting of one of the following elements: at least one gear; at least one tensioner roller and or a toothed roller; a mold, for example a mold of circular shape; a flange, for example a toothed flange.

29. The member of one of claims 17 to 28, consisting of a hard isotropic material.

30. Device for manufacturing transmission elements, in particular belts, by implementing the method of one of claims 1 to 16, comprising: a pulse laser (14) with a duration of less than 5x10 ^{" 13} seconds and of a power greater than 10 ¹² watts on the beam-material interaction surface, - clamping means (12) for clamping a workpiece, a computer (17) for executing a machining program comprising stages of displacement of the focal zone of said pulse laser relative to said part along several axes.

31. The device of claim 30, further comprising a computer (13) for generating said machining program from a three-dimensional representation of the workpiece.