CH718688A2 - Machine for machining a micromechanical part and method of machining implemented by said machine. - Google Patents

Abstract

The present invention relates to a machining machine (1) for a workpiece having an axis of rotation, said machining machine (1) comprising forceless precision machining means (8) arranged to machine the workpiece, at the at least a first spindle (12), a first clamping device arranged to clamp the workpiece and mount it on the first spindle (12), and a piloting system (20). Said machining machine (1) comprises a first optical measuring system (22) of the part arranged to at least measure the real dimensions of the part when it is mounted on the first spindle (12). The piloting system (20) is arranged to continuously pilot control means (20b) of the first optical measurement system (22), comparison means (20c) of the actual measured dimensions of the part with predetermined dimensions of the part to be reached after machining, correction means (20d) for modifying machining parameters as a function of the comparison of the actual measured dimensions of the part with the predetermined dimensions and means for controlling (20e) the means for machining precision without force (8) to control machining then alternately measurements of the real dimensions of the part mounted on the first spindle (12) and machining of the part mounted on the first spindle (12) according to the machining parameters modified in based on the comparison of the actual measured dimensions of the part mounted on the first spindle (12) with the predetermined dimensions, until the actual measured dimensions of the part mounted on the first The spindle (12) correspond to the predetermined dimensions to be achieved, said control system (20) allowing closed-loop machining from the actual measured dimensions of the part. The invention also relates to a method for machining a workpiece by means of such a machining machine (1).

Description

Technical area

The present invention relates to a machine for machining a part, in particular a micromechanical part, having at least one surface of revolution of axis of rotation A, said machining machine comprising precision machining means without force arranged to machine the part, a lathe comprising at least a first spindle having an axis of rotation B extending along the Z axis in an XYZ frame, said first spindle being movable in translation along the Z axis and in rotation around from its axis of rotation B, a first clamping device arranged to clamp the workpiece and mount it on the first spindle, and a control system arranged to manage machining parameters.

The present invention also relates to a method for machining a part, in particular a micromechanical part, implemented by said machining machine.

The present invention also relates to a part, in particular a micromechanical part, machined obtained by such a machining process.

State of the art

[0004] Such parts, in particular micromechanical parts, may for example be precision axes which may be of very small dimensions such as clockwork pivots, such as balance axes for example, involving very small diameters, down to 60 microns or less.

[0005] Traditionally, turning machines by machining without force or without effort, such as turning by femtosecond laser, turning by electroerosion or turning by electrochemical process are controlled in a standard way, that is to say that the parts are machined then extracted from the machining area and measured.

[0006] The results of the measurements are used to correct the machining parameters of the machine in order to obtain the dimensions of the parts within the desired tolerances.

[0007] Therefore, when one proceeds in this way, a machining defect is detected only after the fact relatively long after the part has been completely machined.

[0008] The state of the machining machine will then have every chance of having changed (in terms of thermal expansion or other factors responsible for drift), making the correction of the machining machine based on the measurement of the relatively inaccurate or even erroneous piece.

[0009] On the other hand, traditionally, precision axes machined by turning (including turning by effortless machining, such as turning by femtosecond laser, turning by electroerosion or turning by electrochemical process) from slugs or blanks use traditional turning spindles and counter-spindles provided with clamping by collet, by chuck, or by other existing types of clamping. These types of reworking clamping do not make it possible to guarantee a high level of concentricity of reworking machining. Tailstocks can be used to improve machining, but these are not normally usable for very small parts. We are then forced to machine the entire part in a single clamping, sacrificing the material that is in the clamping. This mode makes it possible to ensure the concentricities between the different diameters of the part. However, the final cut of the part normally requires the use of a counter-spindle which will support the part during this operation. This machining mode does not allow the machining of the part to be divided into spindle and counter-spindle, which reduces the productivity of the machine by a factor of up to 2.

The present invention aims to remedy these drawbacks by proposing a machining machine and a method for machining parts, in particular micromechanical parts, such as watchmaking pivot axes, from blanks or blanks, to obtain machined parts with extreme qualities of concentricity, coaxiality, precision and tolerance.

Disclosure of Invention

[0011] To this end, the invention relates to a machine for machining a part, in particular a micromechanical part, having at least one surface of revolution of axis of rotation A, said machine for machining comprising means for precision machining without force arranged to machine the part, a lathe comprising at least a first spindle having an axis of rotation B extending along the Z axis in an XYZ frame, said first spindle being movable in translation along the Z axis and in rotation around its axis of rotation B, a first clamping device arranged to clamp the workpiece and mount it on the first spindle, and a control system arranged to manage machining parameters.

[0012] According to the invention, said machining machine comprises a first optical measurement system of the workpiece arranged to at least measure the real dimensions of the workpiece when it is mounted on the first spindle by means of the first clamping device , and the control system includes: means for recording predetermined dimensions of the part to be reached after machining with a predefined tolerance, means for controlling the first optical measuring system to measure and record the real dimensions of the part mounted on the first spindle, means for comparing the actual measured dimensions of the part with the predetermined dimensions, correction means for modifying the machining parameters according to the comparison of the actual measured dimensions of the part with the predetermined dimensions, control means of the forceless precision machining means for machining the part as a function of the machining parameters, said control system being arranged to continuously control said control means of the first optical measurement system, said comparison means , said correction means and said means for controlling the machining means for controlling machining then alternately measurements of the actual dimensions of the part mounted on the first spindle and machining of the part mounted on the first spindle according to the parameters of machining modified according to the comparison of the actual measured dimensions of the part mounted on the first spindle with the predetermined dimensions, until the actual measured dimensions of the part mounted on the first spindle correspond to the predetermined dimensions to be reached with said tolerance predefined, said control system allowing closed-loop machining from real dimensions measured from the room.

The present invention also relates to a method of machining a part, in particular a micromechanical part, having at least one surface of revolution of axis of rotation A by means of the machining machine as defined above , said method comprising the following steps: a) recording predetermined dimensions of the part to be achieved after machining with a predefined tolerance; b) bring a workpiece; c) mounting the workpiece in one of the spindles of the machining machine by means of its clamping device; d) machining the workpiece mounted on its rotating spindle by the precision machining means without force; e) measuring the dimensions of the part machined according to the previous step by means of the optical measurement system of the machining machine to obtain real measured dimensions of the part mounted on its spindle; f) comparing the actual dimensions measured in step e) to the predetermined dimensions recorded in step a); g) if the actual dimensions measured in step e) differ from the predetermined dimensions with the predefined tolerance, modifying the machining parameters managed by the control system according to the comparison of the measurements obtained in step f); h) machining the part mounted on its rotating spindle by the precision machining means without force according to the machining parameters modified in step g); i) repeating steps e) to h) until, in step f), the actual dimensions measured in step e) and compared according to step f) correspond to the predetermined dimensions to be reached with said tolerance predefined.

The method according to the invention applies to each part to be machined so that any machined part is then measured and checked.

[0015] Such a machine and such a machining process make it possible to obtain machined parts having extreme qualities of concentricity, coaxiality, precision and tolerance.

Brief description of the drawings

Other characteristics and advantages of the present invention will appear on reading the following detailed description of an embodiment of the invention, given by way of non-limiting example, and made with reference to the appended drawings in which : Figure 1 is a schematic view of a machining machine according to the invention; Figure 2 is a schematic view of a spindle, the clamping device and an optical measurement system; Figure 3 is a schematic view of a spindle and a concentricity correction device; Figure 4 is an enlarged view of a part mounted on its clamping device; Figure 5 is a detail view of Figure 3 showing the spindle, the clamping device and the concentricity correction device; FIG. 6 is a detail view of the clamping device mounted on the spindle and of the concentricity correction device; FIG. 7 is a cross-sectional view of the clamping device mounted on the spindle and of the concentricity correction device; FIG. 8 is a schematic representation of the steps of the method according to the invention; and Figure 9 is a schematic representation of the concentricity correction steps.

Embodiments of the Invention

Referring to Figure 1, the present invention relates to a machine 1 for a part 2, in particular a micromechanical part, having at least one surface of revolution of axis of rotation A. Such a part is represented for example in FIG. 9. This part 2 may for example be a precision pivot pin which may be of very small dimensions as a clockwork pivot pin, involving very small diameters, down to 60 microns or less.

[0018] Such precision axes can be made of hard materials, such as metallic materials of the type hardened steels, stainless steels, Inconel, or metallic glasses, ceramics or materials based on silicon carbide.

[0019] The watchmaking pivot axis comprises at each of its ends a pivot 4, in the extension of a shank 6. Conventionally, at least said pivots have a surface of revolution, and are each intended to pivot in a bearing , typically in an orifice of a stone or ruby.

[0020] The horological pivot axis traditionally has a diameter less than or equal to 2 mm and the pivot 4 has an outer diameter less than or equal to 200 μm, preferably less than or equal to 100 μm, preferably less than or equal to 90 μm , and more preferably less than or equal to 60 μm, when the pivot axis 2 is in the finished state, ready to be used. The pivot 4 is of the conical type for example.

[0021] The horological pivot axis can have a plurality of sections of different diameters, conventionally defining bearing surfaces and shoulders, produced by machining.

[0022] The pivot axis can be a pendulum axis for example. Of course, other types of horological pivot axes can be envisaged, such as, for example, horological mobile axes, typically escapement pinions, barrel arbors or even anchor rods. In this case, the pivot axis may comprise functional elements linked to its use. For example, the axle may comprise a toothing, a thread or a hook for fixing the spring in the case of a barrel arbor. Parts of this type have, at the level of the body, diameters that are preferably less than 2 mm, and pivots with a diameter that is preferably less than 0.2 mm as described above, with an accuracy of a few microns. The part described here is a pivot pin configured to suit preferably watchmaking applications, but it is obvious that it can be used in any other application requiring the same pivot pin configuration.

[0023] The workpiece 2 mounted on the machining machine 1 can be a piece of material that can be machined without effort, a blank or a slug which will be at least partially machined in the machining machine 1 to give a blank, which can then undergo a recovery and/or finishing step by another process if necessary. Preferably, the part 2 to be machined mounted on the machine 1 is a blank which will be entirely machined and finished in the machine 1 to obtain the part having its final dimensions by means of the single and same machine. 1.

The part 2 to be machined mounted on the machining machine 1 can also be a blank, that is to say a part already partially machined by means of another process and another machine, for example by chip removal via a traditional bar turning or conventional machining process or any other material removal method, and which will be taken up and/or finished on the machining machine 1 to obtain the part having its final dimensions.

The machining machine 1 comprises precision machining means without force 8 arranged to machine the part 2. In the present description, machining without force or without effort is called unconventional machining according to which there is no has no mechanical action transmitted by direct contact and force between a tool and the part, unlike conventional machining where there is direct contact between the tool and the part and in which significant cutting forces are involved. A machining without force is therefore a machining without direct contact between the part to be machined and a machining tool which would be capable of exerting a force or a constraint on said part.

Advantageously, the precision machining means without force 8 are arranged to attack the material radially and / or tangentially and / or axially to the workpiece 2 to be machined, while the latter is rotating.

[0027] Advantageously, the means for precision machining without force comprise means for machining by turning by femto laser, by electrochemical turning (electrochemical machining (ECM)), or by turning by electroerosion (for example EDM (electrical discharge machining) by wire).

[0028] Preferably, the precision machining means without force are a femto laser which delivers high-energy pulses over extremely short durations (of the order of 10-15 seconds). This enables material ablation processes without damage to the machining interface. Almost any material can be machined by this process.

Advantageously, the femtosecond pulsed laser is a laser with wavelengths comprised for example between 200 nm and 2000 nm, preferably between 400 nm and 1000 nm, limits included. The characteristics of the laser can be for example: average power between 1 W and 100 W, energy per pulse between 20 µJ and 4000 µJ, frequency between 100 kHz and 1000 kHz, pulse duration between 100 fs and 2 ps.

The laser can be controlled by means of a 2D scan head (2 axes) or a precession head with at least 3 axes, and preferably 5 axes. Such devices are available on the market.

The laser is controlled and programmed to create an action zone 9, in the course of the part 2 to be machined mounted on the machine 1.

[0032] The machining machine also comprises a digital lathe 10 comprising at least a first spindle 12 and a second spindle 14 acting as counter-spindle.

The first spindle 12 has an axis of rotation B extending along the Z axis in an XYZ frame, said first spindle being movable in translation along the Z axis and in rotation around its axis of rotation B.

Similarly, the second pin 14 has an axis of rotation B 'extending along the Z axis in the XYZ reference, opposite the first pin 12, said second pin 14 being movable in translation along the axis Z and in rotation around its axis of rotation B'.

Each pin 12, 14 is driven in rotation, powered by a motor 15 (see Figure 3).

As shown for example in Figures 2 and 4, the first pin 12 is associated with a first clamping device 16 arranged to clamp a first end of the workpiece 2 to be machined, and leave the second end free by exposing the part to be machined of part 2, and to mount said part 2 on said first spindle 12.

Similarly, the second pin 14 is associated with a second clamping device 18 arranged to clamp the second end of the workpiece, and leave the first end free by exposing the other part to be machined of the workpiece 2, and to mount said part 2 on said second pin 14.

The clamping devices 16, 18 will be described in detail later.

The machine also comprises a control system 20 arranged to manage machining parameters which include in particular the operating characteristics of the precision machining means without force 8, such as, for example, in the case of a femto laser, the power, the energy per pulse, the frequency, the pulse duration, the different depths of pass, the movement (circular, oscillatory, ...) of the laser added to its primary movement with respect to the part 2, possibly the angles of attack (eg: precession movements), etc...

[0040] The machining parameters also include the speed of rotation of the spindles 12, 14 (which can be constant or dynamically adjusted, for example synchronized with the speed of the laser beam), and the angle of inclination of the spindles with respect to to the working "plane" or to the two other planes of Cartesian space.

The control system 20 is also arranged to manage the positioning of the precision machining means without force 8 with respect to the workpiece 2 to be machined and the positioning of the clamping device 16, 18 with respect to its spindle 12, 14 respectively.

[0042] The machine 1 can also comprise a part feed device, a loading and unloading robot arranged to take a part from the feed device, position the part in one of the clamping devices on a spindle , then remove it after machining the exposed part, position the part in the other clamping device on the other spindle, then remove the machined part and unload it.

The machine can also include an air conditioning system, a water cooling device for the laser, as well as all the connectors and power supplies necessary for its operation.

According to the present invention, the machining machine 1 comprises a first optical measurement system 22 of the part 2 arranged to at least measure the real dimensions of the part 2 when it is mounted on the first spindle 12 at the means of the first clamping device 16.

Similarly, in particular when the second spindle 14 is used to carry out machining, the machine can advantageously comprise a second optical measurement system 24 of the part 2 arranged to at least measure the actual dimensions of the part 2 when it is mounted on the second spindle 14 by means of the second clamping device 18.

Thus, each system 22, 24 for optically measuring the real dimensions of the part mounted on its spindle is integrated into the machine allowing measurements in situ, without having to remove the part from its spindle.

Advantageously, each optical measurement system 22, 24 comprises telecentric optics 26 associated with telecentric lighting 28 allowing collimated illumination, as shown in Figure 2. Each optical measurement system 22, 24 is arranged to create a field measurement 30 around the part 2 mounted on its clamping device 16, 18, as shown in Figures 1 and 4.

Furthermore, according to the invention, the control system 20 comprises: means 20a for recording predetermined dimensions of the part to be reached after machining with a predefined tolerance, the predetermined dimensions to be reached after machining possibly being the dimensions of a blank when the part to be machined is a piece of material which can be machined without effort, a blank or a blank, partially machined in the machine 1 to obtain said blank, the blank then being finished by another process, or the final dimensions of the part when the piece to be machined is a fully machined and finished blank or a blank finished in machine 1 to obtain said part; control means 20b of the first optical measuring system 22 to measure and record the real dimensions of the part mounted on the first spindle 12; control means 20'b of the second optical measurement system 24, when present, to measure and record the actual dimensions of the part mounted on the second spindle 14; means 20c for comparing the actual measured dimensions of the part with the predetermined dimensions; correction means 20d for modifying the machining parameters, such as the characteristics of the laser or the rotational speed of the spindles 12, 14, according to the comparison of the actual measured dimensions of the part with the predetermined dimensions; control means 20e of the forceless precision machining means 8 for machining the part according to the machining parameters.

In a particularly advantageous manner, the control system 20 is arranged to continuously control said control means 20b of the first optical measurement system 22, said comparison means 20c, said correction means 20d and said control means 20th machining means 8 for controlling a first machining of the exposed part of the part 2 mounted on the first spindle 12, then alternately measurements of the actual dimensions of the part 2 mounted on the first spindle 12 and a machining of the part 2 always mounted on the first spindle 12 according to the machining parameters modified according to the comparison of the actual measured dimensions of the part mounted on the first spindle 12 with the predetermined dimensions, until the actual measured dimensions of the part 2 mounted on the first pin 12 correspond to the predetermined dimensions to be achieved with said predefined tolerance, said control system 20 allowing us Closed-loop engineering from the actual measured dimensions of part 2 mounted on first pin 12.

Similarly, the control system 20 is arranged to continuously control said control means 20'b of the second optical measurement system 24, when present, said comparison means 20c, said correction means 20d and said control means 20e of the machining means 8 for controlling a first machining of the other exposed part of the part 2 mounted on the second spindle 14, then alternately measurements of the actual dimensions of the part 2 mounted on the second spindle 14 and a machining of the part 2 still mounted on the second spindle 14 according to the machining parameters modified according to the comparison of the actual measured dimensions of the part mounted on the second spindle 14 with the predetermined dimensions, until the actual measured dimensions of the part 2 mounted on the second spindle 14 correspond to the predetermined dimensions to be achieved with said predefined tolerance, said control system 20 allowing machining in a closed loop from the actual measured dimensions of the part 2 mounted on the second pin 14.

Thus the control system 20 is arranged to create a closed loop of continuous dimensional checks of the parts and machining corrected according to the previous dimensional check, the part to be machined remaining on its spindle, in its clamping device. The part obtained is machined with extreme precision of the order of less than or equal to ± 1 µm.

The clamping devices 16, 18 and their mounting on their respective spindles 12, 14 are now described in detail with reference to Figures 3 to 7.

[0053] In a particularly advantageous manner, each clamping device 16, 18 comprises a vacuum clamping or holding system for the workpiece 2, such as an integrated Venturi system, arranged to create a vacuum and maintain part 2 pressed into its clamping device 16, 18.

More particularly, and with reference to Figure 7, each clamping device 16, 18 comprises a clamping head 32 having an orifice into which is inserted one end of the workpiece 2 to be machined, said orifice communicating with the Venturi system through channel 34.

In addition, there is also provided a vacuum holding system 36 of the clamping device 16, 18 on its respective spindle 12, 14, connected to the integrated Venturi system, the depression created also allowing each clamping device to be maintained 16, 18 pressed against its respective pin 12, 14, in a fixed position at least during machining.

[0056] In a particularly advantageous way, as the precision machining without force implemented according to the invention, in particular by femto laser, is done without mechanical effort, it is then possible to use a clamping system by the vacuum to hold the part in its clamping device and a vacuum holding system to hold the clamping device on its spindle.

Advantageously, the control system 20 is arranged to control the vacuum in order to be able to move the clamping device in the X-Y plane at least along the Y axis when necessary to correct the concentricity, as will be described below. Thus, each clamping device 16, 18 is arranged to be held on its respective spindle 12, 14 along the Z axis and to be able to be moved in the X-Y plane at least along the Y axis by a command from the control system 20 to correct concentricity.

To this end, each optical measurement system 22, 24 of the part 2 is arranged to also measure the concentricity of said workpiece 2 mounted on its spindle 12, 14, between the axis of rotation A of the part 2 and the axis of rotation B, B' of the spindle 12, 14 respectively.

In addition, the machining machine 1 comprises a concentricity correction device 40 associated with each clamping device 16, 18, said correction device 40 being arranged to be able to move the clamping device 16, 18 in translation. in the X-Y plane along the Y axis.

More particularly, and with reference to Figures 5 to 7, the concentricity correction device 40 comprises a rod 42 arranged to be able to cooperate radially along the Y axis with the outer periphery of the clamping device 16, 18, by support on said perimeter, and a correction cam 44 comprising an eccentric, cooperating with said rod 42 by pressing on said rod 42, and arranged to be driven in rotation by being integral with a shaft 45 driven by a motor 46.

The flange 48 of the pin 12, 14 has a housing 50 in which the clamping device 16, 18 is positioned with a certain clearance at least in Y to be able to position and refocus if necessary said clamping device 16, 18 by relative to the axis of its pin 12, 14. In addition, the housing 50 has a radial opening 52 allowing the passage of the rod 42 to be able to come into contact radially with the said clamping device 16, 18 when it is actuated by the corrective cam 44.

The correction cam 44 is arranged to be controlled by the control system 20 to move the rod 42 in translation along the Y axis, as shown by the arrow F, in order to move the clamping device 16, 18 in translation along the Y axis according to the concentricity to be corrected.

In addition, the control system 20 is arranged to control an angular displacement of the pin 12, 14 in the X-Y plane depending on the concentricity to be corrected.

[0064] More specifically, the control system 20 is arranged to control an angular displacement of the spindle 12, 14 in the X-Y plane and/or to control a movement of the clamping device 16, 18 in translation in the X-Y plane according to the axis Y via the correction device 40 so that the axes of rotation A, B, respectively B' of the workpiece 2 and of its spindle 12, 14 respectively coincide before machining.

Thus, the radial position of each clamping device 16, 18 clamping the part 2 is corrected with respect to the axis of rotation B, B' of the spindle 12, 14 associated before machining, making it possible to obtain a part machined with extreme qualities of concentricity and coaxiality.

Advantageously, each optical measurement system 22, 24 of the part 2 is arranged to measure the actual roughness of the workpiece, the control system 20 being arranged to compare said actual roughness with a predetermined roughness to be achieved, and to modify the machining parameters based on the comparison of the actual roughness of the workpiece with the predetermined roughness.

The invention also relates to the method of machining a part 2, in particular a micromechanical part, having at least one surface of revolution with an axis of rotation A by means of a machining machine 1 such as described above.

The method according to the invention advantageously comprises the following steps, with reference to FIG. 8: a) recording with the recording means 20a of the control system 20 the predetermined dimensions of the part 2 to be reached after machining with a predefined tolerance, corresponding to a model part 54, said predetermined dimensions to be reached after machining being able to be the dimensions of a blank when the part to be machined is a piece of material which can be machined without effort, a blank or a blank, partially machined in the machine 1 to obtain said blank, the blank then being finished by another process, or the final dimensions of the part when the part to be machined is a fully machined and finished blank or a finished blank in the machine 1 to obtain said part; b) provide oneself with a workpiece 2 to be machined; c) mounting the workpiece 2 to be machined in one 12 of the spindles 12, 14 of the machining machine 1 by means of its associated clamping device 16, held by the vacuum, said clamping device 16 having been positioned beforehand centered on its pin 12 and the positioning of the pin 12 and the initial positioning of the precision machining means without force 8, in particular a femto-second laser to correctly position its action zone 9, having been adjusted beforehand by means of a test piece; d) machining by the forceless precision machining means 8, in particular a femto-second laser, the exposed part of the part 2 to be machined by attacking the material radially and/or tangentially and/or axially to the part 2 mounted on its spindle 12 in rotation via its clamping device 16; the machining is programmed to produce the model part 54 as closely as possible; e) measuring and recording the dimensions of the part 2 machined according to the previous step in the measurement field 30 by means of the associated optical measurement system 22 provided in the machining machine 1 and control means 20b of the control system 20 to obtain actual measured dimensions of part 2 mounted on its associated spindle 12; f) comparing the actual dimensions measured in step e) with the predetermined dimensions of the model part 54 recorded in step a) by means of the comparison means 20c of the control system 20; g) if the actual dimensions measured in step e) differ from the predetermined dimensions with the predefined tolerance, modify the machining parameters managed by the control system 20 according to the comparison of the measurements obtained in step f) with the means of correction means 20d; the modified machining parameters are more particularly, in the case of a femto laser, the characteristics of the laser, namely the power, the energy per pulse, the frequency, the pulse duration, and/or the speed of rotation the associated pin 12; h) machining the exposed part of the part 2 by attacking the material radially and/or tangentially and/or axially to the part 2 mounted on its rotating spindle 12 by the precision machining means without force 8, controlled by the means control 20e of the control system 20, as a function of the machining parameters modified in step g); i) repeating steps e) to h) until, in step f), the actual dimensions measured in step e) and compared according to step f) correspond to the predetermined dimensions to be achieved of the part model 54, with said predefined tolerance.

Then, in the case where it is planned to machine the other part of the part 2 after machining the exposed part of the part 2 mounted on the spindle 12, the machining method according to the invention advantageously comprises the following steps: c′) removing, by the robot, the machined part 2 from its clamping device 16 held on the spindle 12 and mounting it in the other spindle 14 of the machining machine 1 by means of its associated clamp 18, held by vacuum, said clamping device 18 having been positioned beforehand in a centered manner on its pin 14 and the positioning of the pin 14 and the initial positioning of the precision machining means without force 8, in particular a femto-second laser to correctly position its action zone 9, having been adjusted beforehand by means of a test piece; d') machining by the forceless precision machining means 8, in particular a femto-second laser, the exposed part of the part 2 to be machined by attacking the material radially and/or tangentially and/or axially to the mounted part 2 on its rotating spindle 14 via its clamping device 18; the machining is programmed to produce the model part 54 as closely as possible; e′) measuring and recording the dimensions of the part 2 machined according to the previous step in the associated measurement field 30 by means of the associated optical measurement system 24 provided in the machining machine 1 and control means 20′b the control system 20 to obtain actual measured dimensions of the part 2 mounted on its associated pin 14; f′) comparing the actual dimensions measured in step e′) with the predetermined dimensions of the model part 54 recorded in step a) by means of the comparison means 20c of the control system 20; g′) if the actual dimensions measured in step e′) differ from the predetermined dimensions with the predefined tolerance, modify the machining parameters managed by the control system 20 according to the comparison of the measurements obtained in step f ') by means of the correction means 20d; the modified machining parameters are more particularly, in the case of a femto laser, the characteristics of the laser, namely the power, the energy per pulse, the frequency, the pulse duration, and/or the speed of rotation the associated pin 14; h′) machining the exposed part of the part 2, by attacking the material radially and/or tangentially and/or axially to the part 2 mounted on its rotating spindle 14 by the precision machining means without force 8, controlled by the control means 20e of the control system 20, according to the machining parameters modified in step g′); i') repeating steps e') to h') until, in step f), the actual dimensions measured in step e') and compared according to step f') correspond to the predetermined dimensions to be achieved from the model part 54, with said predefined tolerance.

These steps of the process for machining part 2 on the second spindle 14 are optional and may or may not be implemented depending on the configurations of part 2.

Advantageously, the machining method according to the invention comprises, before machining according to step d) and/or d'), the following intermediate steps, with reference to FIG. 9: j) measuring the concentricity of the piece 2 to be machined mounted on its spindle 12, 14 between the axis of rotation A and the axis of rotation of the spindle B, B' respectively by the associated optical measurement system 22, 24 respectively, of the processing machine 1; k) correcting the concentricity of the workpiece 2 to be machined with respect to the axis of rotation B, respectively B' of its associated spindle 12, respectively 14, by moving its clamping device 16, respectively 18, by means of the correction of the associated concentricity 40, so that the axes of rotation A, B, respectively B', of the workpiece 2 to be machined and of its associated spindle 12, respectively 14, are coincident.

More particularly, step k) comprises a first sub-step k1) of angular correction of spindle 12, 14 in the XY plane by angular displacement of spindle 12, 14 and therefore of the associated clamping device 16, 18 , the rotation of the spindle 12, 14 being controlled by the control system 20 as a function of the concentricity to be corrected.

[0073] Step k) comprises a second sub-step k2) of radial correction of the clamping device 16, 18 by its displacement in translation in the XY plane along the Y axis, as shown by the arrow F, by means of of the rod 42 coming into radial support, pushed by the correction cam 44 driven in rotation and controlled by the control system 20 according to the concentricity to be corrected. During this sub-step k2, the control system 20 is arranged to control the vacuum in order to be able to move the clamping device 16, 18 in the X-Y plane at least along the Y axis to recenter it with respect to the axis of its associated pin 12, 14.

[0074] The correction of the concentricity is for example necessary when the clamping device is off center with respect to its spindle when the part to be machined is placed in its clamping device. Depending on the position of the clamping device, only step k2) may be necessary. If the axes of the spindle and of the workpiece are coaxial from the start, only step j) of measuring the concentricity is implemented, step k) not being necessary.

Advantageously, step a) of the machining method of the invention can also comprise the recording, with the recording means 20a of the control system 20, of a predetermined roughness of the part to be reached after machining. Step e), respectively e′), then comprises a measurement of the actual roughness of the part 2 by means of the associated optical measurement system 22, 24, step f), respectively f′), then comprises a comparison of said actual roughness with the predetermined roughness to be achieved, step g), respectively g'), then comprises a modification of the machining parameters according to the comparison of the actual roughness of the part with the predetermined roughness, and the steps e) to h), respectively e') to h'), are then repeated until, in step f), respectively f'), the real dimensions and the real roughness measured in step e ), respectively e′), and compared according to step f), respectively f′), correspond to the predetermined dimensions to be reached with said predefined tolerance and to the predetermined roughness to be reached.

The various steps b) to i), c′) to i′), j) and k) described above apply to each part 2 to be machined. All the parts 2 are then measured and checked.

The machining machine 1 and the machining method implemented by said machining machine 1 according to the invention make it possible to carry out closed-loop machining, alternating the in situ dimensional measurements of the parts by optical systems and the machining of the parts according to machining parameters corrected according to the results of said dimensional measurements of the parts, without dismantling the part from its spindle, making it possible to obtain parts machined with extreme precision, less than or equal to ± 1 μm .

In addition, the machining machine 1 and the machining method implemented by said machining machine 1 according to the invention make it possible, before machining, to measure by optical systems the concentricity of rotation of the part. to be machined in its spindle and to correct the radial position of the workpiece clamping device with respect to the axis of rotation of its spindle according to the concentricity measurement carried out, making it possible to obtain machined parts with extreme qualities of concentricity and coaxiality.

[0079] It is obvious that the concentricity correction device 40 and the elements necessary for its operation can be used in a machining machine to recenter the clamping device of a part with respect to its spindle independently of the closed-loop machining described above.

Claims (21)

1. Machining machine (1) of a part (2) having at least one surface of revolution with axis of rotation A, said machining machine (1) comprising means for precision machining without force (8 ) arranged to machine the part, a lathe (10) comprising at least a first spindle (12) having an axis of rotation B extending along the Z axis in an XYZ frame, said first spindle (12) being movable in translation along the Z axis and in rotation around its axis of rotation B, a first clamping device (16) arranged to clamp the workpiece (2) to be machined and mount it on the first spindle (12), and a control system (20) arranged to manage machining parameters, characterized in that said machining machine (1) comprises a first optical measurement system (22) of the workpiece (2) arranged to at least measure the real dimensions of the part (2) when it is mounted on the first spindle (12) by means of the first clamping device (16), and in that the control system (2 0) includes: – recording means (20a) of predetermined dimensions of the part to be reached after machining with a predefined tolerance, – control means (20b) of the first optical measurement system (22) for measuring and recording the real dimensions of the part (2) mounted on the first spindle (12), – comparison means (20c) of the actual measured dimensions of the part (2) with the predetermined dimensions, – correction means (20d) for modifying the machining parameters according to the comparison of the actual measured dimensions of the part (2) with the predetermined dimensions, – control means (20e) of the precision machining means without force (8) for machining the part (2) according to the machining parameters, said control system (20) being arranged to continuously control said control means (20b) of the first optical measurement system (22), said comparison means (20c), said correction means (20d) and said control means (20e) forceless precision machining means (8) for controlling machining then alternately measurements of the actual dimensions of the part (2) mounted on the first spindle (12) and machining of the part (2) mounted on the first spindle (12) according to the machining parameters modified according to the comparison of the actual measured dimensions of the part (2) mounted on the first spindle (12) with the predetermined dimensions, until the actual dimensions measurements of the part (2) mounted on the first spindle (12) correspond to the predetermined dimensions to be reached with said predefined tolerance, said control system (20) allowing closed-loop machining from the actual measured dimensions of the part ( 2). 2. Machining machine according to claim 1, characterized in that the lathe (10) comprises a second spindle (14) having an axis of rotation B 'extending along the axis Z opposite the first spindle (12 ), said second spindle (14) being movable in translation along the Z axis and in rotation around its axis of rotation B', in that the machining machine (1) comprises a second clamping device (18) arranged for clamping the workpiece (2) to be machined and mounting it on the second spindle (14) and a second optical measuring system (24) of the workpiece (2) arranged to at least measure the actual dimensions of the workpiece (2) when 'it is mounted on the second spindle (14) by means of the second clamping device (18), the control system (20) comprising control means (20'b) of the second optical measurement system (24) for measuring and recording the actual dimensions of the part (2) mounted on the second spindle (14) and being arranged to continuously drive said means of c control (20'b) of the second optical measuring system (24), said comparison means (20c), said correction means (20d) and said control means (20e) of the forceless precision machining means (8 ) to order machining then alternatively measurements of the actual dimensions of the part (2) mounted on the second spindle (14) and machining of the part (2) mounted on the second spindle (14) according to the modified machining parameters based on the comparison of the actual measured dimensions of the part (2) mounted on the second spindle (14) with the predetermined dimensions, until the actual measured dimensions of the part (2) mounted on the second spindle (14 ) correspond to the predetermined dimensions to be achieved with said predefined tolerance. 3. Machining machine according to one of the preceding claims, characterized in that the forceless precision machining means (8) are arranged to attack the material of the workpiece (2) to be machined radially and/or tangentially and / or axially to said part (2). 4. Machining machine according to one of the preceding claims, characterized in that the precision machining means without force (8) comprise means for machining by turning by femto laser, by electrochemical turning, or by turning by spark erosion. 5. Machining machine according to one of the preceding claims, characterized in that the optical measuring system (22, 24) comprises telecentric optics (26) associated with telecentric lighting (28). 6. Machining machine according to one of the preceding claims, characterized in that the clamping device (16, 18) comprises a vacuum clamping system of the workpiece (2) to be machined. 7. Machining machine according to one of the preceding claims, characterized in that it comprises a vacuum holding system (36) of the clamping device (16, 18) on its respective spindle (12, 14). 8. Machining machine according to one of the preceding claims, characterized in that the clamping device (16, 18) is arranged to be held on its respective spindle (12, 14) along the Z axis and to be able to be moved in an X-Y plane at least along the Y axis by a command from the piloting system (20). 9. Machining machine according to claim 8, characterized in that the optical measuring system (22, 24) of the workpiece (2) is arranged to measure the concentricity of the workpiece (2) to be machined mounted on its spindle ( 12, 14) between the axis of rotation A and the axis of rotation B, respectively B' of the spindle (12, 14), in that the machining machine (1) comprises a correction device (40) concentricity associated with a clamping device (16, 18), said correction device (40) being arranged to be able to move its clamping device (16, 18) in translation in the X-Y plane along the Y axis, and in that the control system (20) is arranged to control an angular displacement of the spindle (12, 14) in the X-Y plane and/or to control a displacement of the clamping device (16, 18) in translation along the axis Y via its correction device (40) so that the axes of rotation (A, B, B') of the workpiece (2) to be machined and of its spindle (12, 14) coincide before machining. 10. Machining machine according to claim 9, characterized in that the concentricity correction device (40) comprises a rod (42) arranged to be able to cooperate with the associated clamping device (16, 18) and a correction (44) cooperating with said rod (42) and arranged to be driven in rotation and controlled by the control system (20) to move said rod (42) along the Y axis in order to move the clamping device (16, 18) in translation along the Y axis depending on the concentricity to be corrected. 11. Machining machine according to one of the preceding claims, characterized in that the optical measuring system (22, 24) of the workpiece (2) is arranged to measure the actual roughness of the workpiece (2) to be machined, and in that the control system (20) is arranged to compare said real roughness with a predetermined roughness to be achieved, and to modify the machining parameters according to the comparison of the real roughness of the part (2) with the predetermined roughness. 12. Machining machine according to one of the preceding claims, characterized in that the machining parameters comprise the operating characteristics of the precision machining means without force (8), the speed of rotation of the spindles (12, 14) and the inclination of the spindles (12, 14). 13. Machining machine according to one of the preceding claims, characterized in that the predetermined dimensions to be achieved after machining are the dimensions of a blank when the part (2) to be machined is a piece of material which can be machined without effort, a blank or a billet, partially machined to obtain said blank, or the final dimensions of the part when the part (2) to be machined is a machined billet or a finished blank to obtain said part. 14. Method of machining a part (2) having at least one surface of revolution of axis of rotation A by means of a machining machine (1) according to one of claims 1 to 13, characterized in that said method comprises the following steps: a) recording predetermined dimensions of the part to be achieved after machining with a predefined tolerance; b) provide oneself with a workpiece (2) to be machined; c) mounting the workpiece (2) to be machined in one of the spindles (12) of the machining machine (1) by means of its clamping device (16); d) machining the part (2) mounted on its rotating spindle (12) by the forceless precision machining means (8); e) measuring the dimensions of the part (2) machined according to the previous step by means of the optical measuring system (22) of the machining machine (1) to obtain real measured dimensions of the part (2) mounted on its spindle (12); f) comparing the actual dimensions measured in step e) to the predetermined dimensions recorded in step a); g) if the actual dimensions measured in step e) differ from the predetermined dimensions with the predefined tolerance, modify the machining parameters managed by the control system (20) according to the comparison of the measurements obtained in step f ); h) machining the part (2) mounted on its spindle (12) in rotation by the precision machining means without force (8) according to the machining parameters modified in step g); i) repeating steps e) to h) until, in step f), the actual dimensions measured in step e) and compared according to step f) correspond to the predetermined dimensions to be reached with said tolerance predefined. 15. Machining method according to claim 14, characterized in that said method comprises, after machining the part on one of the spindles (12), the following steps: c') removing the workpiece from one of the spindles (12) and mounting it in the other spindle (14) of the machining machine (1) by means of its clamping device (18); d') machining the part (2) mounted on its spindle (14) in rotation by the precision machining means without force (8); e') measuring the dimensions of the part (2) machined according to the previous step by means of the optical measuring system (24) of the machining machine (1) to obtain real measured dimensions of the part (2) mounted on its pin (14); f) comparing the actual dimensions measured in step e′) with the predetermined dimensions recorded in step a); g′) if the actual dimensions measured in step e′) differ from the predetermined dimensions with the predefined tolerance, modify the machining parameters managed by the control system according to the comparison of the measurements obtained in step f′ ); h′) machining the part (2) mounted on its spindle (14) in rotation by the precision machining means without force (8) according to the machining parameters modified in step g′); i′) repeating steps e′) to h′) until, in step f′), the actual dimensions measured in step e′) and compared according to step f′) correspond to the dimensions predetermined to be achieved with said predefined tolerance. 16. Machining method according to one of claims 14 and 15, characterized in that it comprises, before machining according to step d) or d′), the following intermediate steps: j) measuring the concentricity of the workpiece (2) to be machined mounted on its spindle (12, 14) between the axis of rotation A and the axis of rotation (B, B') of the spindle (12, 14) by the associated optical measuring system (22, 24) of the machining machine (1); k) correcting the concentricity of the workpiece (2) to be machined with respect to the axis of rotation (B, B') of its spindle (12, 14) by moving its clamping device (16, 18) so that the axes of rotation (A, B, B') of the workpiece (2) to be machined and of its spindle (12, 14) coincide. 17. Machining method according to one of claims 14 to 16, characterized in that step a) comprises recording a predetermined roughness of the part to be achieved after machining, in that step e) , respectively e'), comprises a measurement of the actual roughness of the part (2) by means of the associated optical measurement system (22, 24), in that step f), respectively f'), comprises a comparison of said actual roughness with the predetermined roughness to be achieved, in that step g), respectively g'), comprises a modification of the machining parameters according to the comparison of the actual roughness of the part with the predetermined roughness, and in that steps e) to h), respectively e') to h'), are repeated until, in step f), respectively f'), the actual dimensions and the actual roughness measured at step e), respectively e'), and compared according to step f), respectively f'), correspond to the predetermined dimensions to be achieved with said predefined tolerance and the predetermined roughness to be achieved. 18. Machining method according to one of claims 14 to 17, characterized in that the precision machining means without force (8) comprise means for machining by turning by femto laser, by electrochemical turning, or by EDM turning. 19. Machining method according to one of claims 14 to 18, characterized in that the machining parameters include the operating characteristics of the precision machining means without force (8), the speed of rotation of the spindles ( 12, 14) and the inclination of the spindles (12, 14). 20. Machining method according to one of claims 14 to 19, characterized in that the predetermined dimensions to be achieved after machining are the dimensions of a blank when the part to be machined is a piece of material which can be machined without effort, a raw or a billet, partially machined to obtain said blank, or the final dimensions of the part when the part to be machined is a machined billet or a finished blank to obtain said part. 21. Machined part obtained by the machining process according to one of claims 14 to 20.