CH705707B1 - A method of manufacturing components of synchronous and asynchronous transmission and components of synchronous and asynchronous transmission obtained according to this method. - Google Patents

Abstract

The present invention presents a method of manufacturing a component intended for a synchronous / asynchronous transmission of movements / power, characterized in that it describes shapes to be machined from the geometry defined on a 3D CAD plane, data transfer. on three-dimensional machining software taking into account inter alia interpolations of the left surfaces, defines steps according to the material and the machining depth so that the ablation conditions are optimized, introduces data into the computer science for controlling / controlling the displacements (17), in the Y direction, the focal zone D is positioned by illumination with the aid of the optical head (15), equipped or not with a diffraction device, positioned on the plane E , the component to be machined (10), clamps the component to be machined (10) by means of clamping means (12), adjusts the ultra-short pulse laser femto to values lower than 500 fs (5 × 10 - 13 seconds), starts the machining program and starts the component (10) with a femto laser.

Description

The present invention relates to a method of components for a production of transmission of motion / synchronous / asynchronous power by cutting the components using a short-pulse laser femto type. The invention also relates to the motion transmission components / synchronous / asynchronous power obtained by this method.

[0002] In the mid-1960s, the first lasers were bulky, fragile and large energy consumers. Shortly after its invention, the laser caused a real revolution by producing a flash much shorter, of the order of one nanosecond (10 <-> <9> seconds). In the early 1970s, we reached the picosecond (10 <-> <12> seconds), then a hundred femtoseconds (10 <-> <15> seconds) in the early 1980s. Finally, pulses of 6 fs were obtained in 1987 This technical feat, performed at Bell Laboratories in the United States, has not been improved since it approaches the theoretical limit for a visible light pulse. Nevertheless, the production conditions of these pulses are now simpler and much better controlled, so that durations of 10 femto seconds are commonly obtained in the laboratory.

The use of YAG or CO 2 lasers is relatively conventional in the machining of materials such as metals or excimer for polymers. These methods are limited when working in small dimensions on materials that do not withstand shocks or thermal stresses.

[0004] Today lasers that emit ultrashort pulses (less than ten femto seconds) are compact, versatile and reliable. The intensity and diversity of these lasers are constantly increasing: the beams obtained today cover the entire electromagnetic spectrum, from X-rays to T-rays (terahertz radiation, located beyond the infrared) and the maximum powers. reach several petawatts (several billion megawatts).

These devices apply in particular in physics, chemistry, biology, medicine, optics.

More than thirty years after its invention, the laser has given rise to multiple developments, among which ultra-short pulse lasers.

Because of the extremely short duration of their pulses, they make possible the study of ultrafast phenomena occurring at the microscopic or atomic scale. In addition, very high powers can be produced during the short duration of the pulse, creating extreme conditions, comparable to those found in astrophysics.

With ultrashort pulsed lasers, any material such as diamond, ceramics, plastics, wood, etc. is precisely milled.

The use of the ultra-short pulse laser for machining mechanical components represents considerable advantages: more precise optical machining means; removal of material under substantially athermic conditions: there is no effect except in the hearth, the beam can cross thicknesses to go to work at a point in the mass without altering the surface or the material on the way traveled; the beam is manipulated remotely and from all angles; there is no restriction on machined materials; a resolution finer than the width of the laser beam is obtained by adjusting the laser so that only the intensity of the central part, the brightest, is greater than the ablation threshold of the material; absence of cutting forces at the machining level.

[0010] It is known that synchronous / asynchronous motion / power transmissions cover an extremely wide field of application in all sectors of the industry, including that of watchmaking.

Many solutions exist to transmit the movements / powers as, for example, those involving gear transmission as proposed by most traditional watch movements. These solutions are limited in the general case where the spacings are distant and where the motors and receivers are not parallel.

A transmission of movement / power, is constituted in particular by a set belt / pulleys. It is asynchronous when the belt used is smooth (rubbing strips) and synchronous when the belt used is toothed.

It should be noted that the asynchronism comes from the possibility of slipping of the belts on the pulleys under the action of too much torque. To overcome this drawback, at least partially, it is necessary to add a tensioning device and / or guide called roller, which is not always the case with regard to synchronous transmission chains.

The gears, pulleys, gears and tension rollers are made by traditional methods such as turning and / or milling. The traditional belts are made in particular by molding, the molds being made by electroerosion, ultrasound or by the LIGA process (Lithography, Galvanization, Abformung).

These methods are useful in particular for the production of micro-molds whose dimensions go beyond 2 mm and directs the manufacturer to use "injectable plastics" which is limiting for dimensions below 2 mm and for the use of materials such as metals, composites, ceramics, minerals and organic complex matrix materials. Moreover, these methods also have limitations concerning the machining of complex surfaces, in particular left-handed surfaces.

EP 0 851 295 (MIMOTEC SA) provides a metal covering without specifying the particular case of holes and blind surfaces. This document is useful for making microstructures by the LIGA method which is a method of reverse revelation and does not represent micro-molding in general. Fields of complex materials and small dimensions escape this process since only certain plastics can be molded subject to viscosity constraints with very small dimensions. This process has gaps for the realization of sandwich or composite structures.

In order to overcome the problems of large distances and axial offsets, it is known to use a device using power / movement transmissions by micro smooth or toothed belts, as illustrated in the publication WO 2004/006 026. A2 (TAG-HEUER SA).

This known device can significantly reduce the quality constraints of the movements / power transmissions required especially in the field of watchmaking. However, the advantages of this device are not fully realized because of the quality of the components allowing the transmission of movements / power that are achieved in particular by conventional methods previously seen.

Said conventional manufacturing processes are unsuitable when it comes to synchronous and asynchronous movements / power transmissions comprise non-standardized belts and intended in particular in the field of watchmaking.

Indeed, from a normative point of view, the ISO standards govern the field of synchronous / asynchronous belt movements / power transmissions when the dimensioning relative to the thicknesses of reinforcements, belt widths and tooth heights goes to beyond 2 mm, which is not the case when this dimensioning remained below 2 mm.

The object of the present invention is to provide a method for manufacturing synchronous and asynchronous synchronous / motion transmission components, as well as the synchronous and asynchronous synchronous and synchronous power / motion transmission components obtained according to this method, in order to respond to quality constraints, required in particular in the field of watchmaking, and allowing the use of complex materials without limitation of dimensioning.

This object is achieved by a method of manufacturing synchronous / asynchronous movement / power transmission components which describes shapes to be machined from the geometry defined on a 3D CAD plane, transfers the data to a software package. three-dimensional machining taking into account, in particular, interpolations of the left surfaces, defines steps according to the material and the machining depth so that the ablation conditions are optimized, introduces data into the computer control / piloting of the displacements, in the Y direction, the focal zone C by illumination with the aid of the optical head A, whether or not equipped with a diffraction device, positions the component to be machined on the plane B, clamps the component to be machined to using conventional systems such as flanges, adhesive, etc., adjusts the ultra-short femto pulse laser to less than 500 fs (5 × 10 <-> <13> seconds), starts the machining program and factory component by femto laser.

Thus, synchronous and asynchronous synchronous and synchronous power transmission / transmission components that meet the quality constraints required by the watch industry, namely: the choice of materials (mechanical properties and manufacturing processes); the difficulty of using the loaded structures (reinforcements reinforced with fibers, etc.); the definition of tooth profiles; the difficulty of machining.

The ultra short pulse laser does not diffuse heat outside the irradiated volume, regardless of the machined material.

The machining process is based on the ablation process that implements complex phenomena. The athermal nature of the process is due to the brevity of the conjugated pulses at a very high intensity of the order of 1014 Watt / cm <2> at the focal plane of the beam. The current trend directs the tools to pulses of 100 fs (1.0 × 10 <-> <13> seconds) for an energy of the order of MJ / pulse.

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

This procedure uses the light-material interface to cause local ablation of any material. Beyond marked thermal incidence, the ablation accuracy is significantly improved compared to conventional lasers of the pico second or excimer type.

The fluences required in the case of the machining range from 0.25 to a few tens of J / cm <2> depending on the desired speed and machining quality, typically 0.5 ~ 0.25 microns / pulse.

In one embodiment, the machining is done in the open air or controlled atmosphere (neutral gas). The advantage of machining in a controlled atmosphere is to avoid the phenomena of air breakdown at the focal plane and the corollary appearance of instability very partially altering the machining quality. Moreover and in order to improve the energy efficiency of the ablation, it is possible to add on the laser, in the case of industrial series, qualitative optics such as for example a diffractive set.

It will be noted that the use of an ultrashort pulse laser allows: in plastic materials (thermoplastics, polymers ...), cutting without thermal damage of the size area. in composite materials, the direct size without delamination of the multilayer material. the machining of all metals without formation of sagging or burring or even flaring at the incident surface. in ceramics, glassware, ultra-hard mineral products, including diamond, the size occurring without alteration of the surfaces or formation of networks of necking or cracking.

In general, machining operates without difficulty on the scale of ten microns. By using this tool we confirm the size of micro transmission whose tooth height (belts or wheels) is of the order of 5 microns. The limits of the technique are only those related to the beam offset.

The present invention allows the use of complex materials without limitation of sizing and the realization of sandwich-type or composite structures and meets the quality requirements of the motion / power transmissions when the motor-receiver axes are in particular parallel and geometric constructions such as: simple cases called parallel strands; simple cases called cross-strands.

The movements / power transmissions performed according to the invention are of the asynchronous and / or synchronous type.

In one embodiment, the movements / power transmissions are asynchronous and consist of at least one friction wheel, a belt and have at least one tension roller and / or guide which is located inside or outside the micro-belt.

Furthermore, the motion transmission components / asynchronous power are mounted on pivot or translation links which allows: to increase the winding angle on the pulleys; to provide clutch / disengagement functions.

Synchronous motion / power transmissions consist of at least one gear and toothed belts, which has the effect of allowing the transmission of mechanical power between a motor element and a slip-free receiving element, thus correcting the problem posed by the functional or accidental sliding of asynchronous transmissions, especially in case of overload.

Asynchronous movements / power transmissions comprise friction wheels, tension rollers and / or guide and flat or trapezoidal or striated belts.

Synchronous motion / power transmissions notably comprise gears and / or toothed belts characterized by: a carrier geometry with controlled deformation (elastic domain of the material); teeth with a curvilinear or polygonal profile; an ortho-radial, straight, inclined or curvilinear set on the carrier plane.

The components of a movement / power transmission made according to the present invention are made of material having sufficient mechanical characteristics, which is the case especially for plastics and polymers, metals, composites and ceramics.

The present invention also allows for the process proposed by the present invention micro-molds.

The invention also relates to a timepiece or a clockwork movement comprising a movement / power transmission made according to the present invention.

Other features of the invention are set forth in the dependent claims.

The invention will be better understood from the following detailed description with reference to the accompanying diagrammatic drawings in which: <tb> - fig. 1 <sep> represents, by way of example, a device for manufacturing synchronous / asynchronous movements / power transmissions. <tb> - fig. 2 <sep> represents a synchronous / asynchronous transmission of movements / power relative to a simple case called parallel strands. <tb> - fig. 3 <sep> represents a profile of curvilinear teeth. <tb> - fig. 4 <sep> represents two examples of asynchronous transmission with secondary pulleys arranged inside and outside the transmission. <tb> - fig. <Sep> is a sectional view of a laminated belt.

FIG. 1 illustrates a device for manufacturing a synchronous / asynchronous movement / power transmission (10) comprising: a work plane (11) having in particular six programmable axes (A, B, C, X, Y, Z) and clamping means (12); a computer (13) including a software for 3D CAD; a femto-type ultra-short pulse laser (14) comprising an optical head (16) for emitting a beam (18) focused on a focal area (D); a control computer / driver displacements (17).

A method for manufacturing components of a synchronous / asynchronous transmission of movements / power comprises in particular the following steps: description of the shapes to be machined from the geometry defined on a 3D CAD plane; data transfer on a three-dimensional machining software taking into account in particular interpolations of the left surfaces; defining the steps according to the material and the machining depth so that the ablation conditions are optimized; introduction of data into control computer / motion control (17); positioning, in the Y direction, of the focal zone D by illumination with the aid of the optical head (15), equipped or not with a diffraction device; positioning on the plane E of the component to be machined (10); clamping the component to be machined (10) by means of clamping means (12); adjustment of the ultra-short pulse laser femto less than 500 fs (5 × 10 <-> <13> seconds); start of the machining program and machining of the component (10) by femto laser.

Comparative experiments indicate that going from 100 to 10 fs substantially improves machining accuracy. The fluences used in micro-machining typically vary from 0.2 ~ 50 J / cm <2> depending on the desired quality and machining speed. The ablation rates represent a few μm / pulse according to the machined materials.

It should be noted that the combination of rotations and translations along the six axes (A, B. C, X, Y, Z) of the space allows machining any component (10), even complex.

In order to avoid the appearance of non-linear phenomenon due to the breakdown of air, it will be possible to machine under vacuum or under projection of neutral gas (helium, argon, etc.). Controlled atmosphere machining also significantly improves the quality of machining. In the case of specific applications, it will be possible to improve the optical precision by adopting a diffraction system mounted in addition to the focusing device.

FIG. 2 illustrates a transmission / synchronous / asynchronous power (10) by belt which comprises in particular a main pulley (23), a belt (20), a secondary pulley (22) and a tensioner roller (21). The main pulley (23) is flat and provided on its periphery equidistant radial teeth comparable to a flat gear wheel. The main pulley (23) is provided with a flange (not shown) to guide the belt (20).

It should be noted that the belts (20) have in particular curvilinear tooth profiles (30), as shown in FIG. (3).

When producing a synchronous transmission, the flanges (not shown) are disposed on a single pulley (23) and preferably that having the smallest diameter.

Furthermore, for each type of tooth profile there are teeth with straight flanks or involute (not shown).

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). ) to guide the belt (20) on said transmission (10).

The belts (20) are in particular of flat section, trapezoidal or striated.

The method which is the subject of the present invention allows the use of any materials adapted to the components of the transmission (10), namely: plastics; metals; composites; ceramics; the minerals; organic complex matrix materials.

Most forms machined on the elements involved in the production of the transmissions (10) can be machined in a plane. To do this, we use machining techniques in 2D or 2D1 / 2.

In the case of machining more complex surfaces such as complex teeth (not shown), the beam (16) of the laser is moved along three axes simultaneously or even four axes with a rotating plane (11) and a optical head (15) pivoting.

Ultrafast laser machining responds to the manufacture of all the forms that go into the realization of microphones and nano transmissions.

In general, all the molds machined by the process described in the invention, and whatever their type, consist or use a number of functional subassemblies: the molding elements: impression (punch and matrix) the functional elements carcass, feed, mechanisms of release and demolding of the injected parts, temperature control devices of the mold ancillary elements: fasteners and manipulators, centering systems, robots for placing prisoners and extraction of molded parts, safety devices and demolding controls.

The method of machining a mold by femto laser will focus on the realization of a cavity cavity in which the three-dimensional negative representation of the object (all dimensional corrections included) is limited by both parties what are the punch and the matrix.

This method allows the realization of any micro or nano molded part since the art of molding is preserved and the viscosities allow it (very small dimensions).

Note that the aforementioned method is applicable to all mouldable materials without exception and that the results obtained on the surface conditions are excellent, which is important especially for the friction parts.

The invention also relates to a timepiece or a watch movement comprising a movement / power transmission made according to the present invention. Indeed, from a functional point of view, a watch movement represents a synchronous kinematic chain characterized by the absence of sliding in contact with the transmission members.

Claims (14)

1. A method for manufacturing a component intended for synchronous / asynchronous movement / power transmission, characterized in that it comprises the following steps - description of the shapes to be machined from the geometry defined on a 3D CAD plane, Transfer of the data to a three-dimensional machining software taking into account, in particular, interpolations of the left surfaces, - Definition of the steps according to the material and the depth of machining so that the conditions of ablation are optimized, - introduction of the data in the computer control and / or control of displacements (17) of a beam (16) of a femto laser (14), Positioning, in a direction (Z), a focal zone (D) by illumination with the aid of an optical head (15) of the femto laser (14), equipped or not with a diffraction device, Positioning on a plane (E) of the component to be machined (10), - clamping the component to be machined (10) by means of clamping means (12), - adjustment of the femto laser with pulses less than 500 fs, - start of the machining program and machining of the component (10) by femto laser. 2. Method according to claim 1, characterized in that it is carried out under controlled atmosphere to prevent the occurrence of non-linear phenomena due to breakdown of air. 3. Method according to one of claims 1 to 2, comprising a step of machining the component using 2D machining techniques. 4. Method according to claim 1, characterized in that the component is a toothed belt. 5. Method according to claim 1, characterized in that the component is a belt which has a curvilinear toothing. 6. Method according to claim 1, characterized in that the component is a belt of flat section, trapezoidal or striated. 7. Method according to claim 1, characterized in that the component is a toothed pulley. 8. Method according to claim 1, characterized in that the component is a toothed roller. 9. Method according to claim 1, characterized in that the component is a flange for toothed pulley. 10. The method of claim 1, characterized in that the component is a gear which has a curvilinear toothing. 11. An assembly comprising at least one friction wheel, a belt and at least one tension / guide roller and intended to form an asynchronous movement / power transmission, characterized in that these components are obtained by the process according to claim 1. 12. Watch comprising a component obtained according to the method according to one of claims 1 to 10 or an assembly according to claim 11. Clockwork movement comprising a component obtained according to the method according to one of claims 1 to 10 or an assembly according to claim 11. 14. Belt obtained according to the method of claim 1, characterized in that it is toothed.