FR2899147A1 - Decorative laser marking on non-flat parts by using decorative materials e.g. plastics, comprises modeling and generating of three-dimensional polylines in space, generating three-dimensional vectors, and real-time processing of vectors - Google Patents

Abstract

The process for decorative laser marking on non-flat parts by using decorative materials such as such as plastics, crude or anodized aluminum, crude or coated metal, raw or coated wood or composite, or analogues, comprises modeling and generating of three-dimensional polylines (3) in a space, generating three-dimensional vectors (6), real-time processing of three-dimensional vectors, generating three-dimensional route planning system (12, 14), managing and generating controlling parameters of a laser source (11), and controlling a three-dimensional deviation system (13, 15). The process for decorative laser marking on non-flat parts by using decorative materials such as such as plastics, crude or anodized aluminum, crude or coated metal, raw or coated wood or composite, or analogues, comprises modeling and generating of three-dimensional polylines (3) in a space, generating three-dimensional vectors (6), real-time processing of three-dimensional vectors, generating three-dimensional route planning system (12, 14), managing and generating controlling parameters of a laser source (11), and controlling a three-dimensional deviation system (13, 15). The parts have a dimension, which is higher than a meter and can be several decimeters. The three-dimensional deviation system comprises a linear optical axis. The controlling parameters of the laser source are designed that is suitable to act by power, frequency, or hashing of that source and to execute welding operations. An independent claim is included for a device for decorative laser marking on non-flat parts.

Description

The invention relates to a method for laser marking decorations on

  flat or non-planar parts, of all materials used in decorations such as plastics, raw or anodized aluminum, raw or coated metals, raw or coated wood or composites, or the like, the largest dimension of which may reach several decimetres, and may include The invention also relates to a device for implementing this method.

  The invention will find its application in many industrial sectors, in which appearance parts receive a functional and / or aesthetic decoration, and will find a particular interest in the automotive field. The parts to be treated are, depending on the case, raw, painted or even undergo a chemical treatment allowing more elaborate renderings. The constraints are essentially of two kinds: - the decorations made must not have any visible discontinuities; The method used, in its implementation, must make it possible to cover the range of aesthetic rendering required by the application, and in particular, in the most requested applications: - the establishment of the possible paint layer, in order to reveal an underlay in contrast with the initial color of the piece. The thickness of the layer is constant on a given piece model, but may vary from model to model; - partial removal of the surface (contrast less accentuated for a more discreet rendering); 30 - modification of the surface state by a color change. The material, previously treated, has its color modified under the effect of the laser; - Digging, the final rendering can be improved by a subsequent deposit (varnish for example). 35 - thermal effect (gray, black or "burnt" rendering).

  The complexity of the decorations, combined with that of the shapes of the rooms to be decorated, makes it necessary to use a control system, such as a programmable computer, which must make it possible to offer flexibility of use: - rapid creation of programs: - easy import of existing patterns and flexibility in set design; - accessibility of the settings - saving of the realized programs: - memorization of the geometry of the decorations; - storage of the rendering parameters. simple and fast loading of existing programs The user expects the same flexibility in the production of parts, and wants to have the means to achieve indifferently prototypes, unit work or small series, or a production of medium or large series , without requiring lengthy and costly changes of production, or testing new achievements. In view of this problem, it has so far been imagined to use laser marking means, because of their theoretical capacity to meet the aesthetic criteria required, and to offer a precision of line or decoration superior to prior art techniques. of the state of the art, such as screen printing, mechanical engraving, or the like.

  The theoretical capacity of the laser marking to fulfill the requested functions comes up, however, to a difficulty when decorating large flat parts, and, moreover, when decorating left parts. The difficulty is related to the problem of concentration of the light beam, in the case of the decoration of areas remote from the source. The use of optical systems, focal length in general less than 300mm, can decorate surfaces of the order of 350mm x 350 mm. But the problem quickly becomes insoluble, when it comes for example to decorate a car body panel, a highly warped piece such as a wing or an interior trim, such as console, dashboard stick or even door. Such parts can reach a developed length greater than one meter, and existing systems are not usable in the state. To overcome this difficulty, it has been imagined to segment the surface to be decorated in fields of dimensions capable of being processed by the existing means. However, this procedure quickly meets its limits, precisely because of the difficulty of repositioning and joining the areas successively treated by the marking means (by displacement, or marking means, or the piece to decorate, or both ). The optical defects are inevitable, and make the piece unsuitable for use, especially in the automotive field where an irreproachable quality of finish is required. The focus problem of the beam is reflected, again, by a different rendering according to the distance, with respect to the source, of the zone to be decorated.

  Existing systems generally combine the use of integral mirrors of square-mounted galvanometer frames which deflect the laser beam from a source according to the electrical signals applied to both. galvanometers, and a flat field lens, so as to cover the entire surface to be decorated. Such an objective, expensive, does not guarantee the perfection of geometry for a three-dimensional decoration of large size, and alters the distribution of the density of energy provided on the surface to be decorated.

  The system according to the invention offers the possibility of engraving patterns in a three-dimensional field of large size, and to guarantee the continuity and accuracy of the decorating patterns. For this purpose, the invention consists of a laser marking process of decorations on plane or non-flat parts, of all materials used in decorations such as plastics, raw or anodized aluminum, raw or coated metals, wood or composites raw or coated, or the like, whose largest dimension may reach several decimetres, and may especially be greater than one meter, characterized in that it comprises the steps of: - modeling and generation of three-dimensional polylines in space - generation of three-dimensional vectors - real-time processing of three-dimensional vectors - generation of three-dimensional displacement instructions - management and generation of control parameters of at least one laser source - control of a three-dimensional deflection system. According to another characteristic of the invention, the three-dimensional deflection system comprises a linear optical axis.

  According to yet another characteristic of the invention, the control parameters of the laser source are designed able to act on the power, the frequency, or the hash of this source. The invention also consists in a device for implementing such a method, characterized in that it comprises a linear optical axis consisting of a lens that is mobile in the direction of the beam emitted by a laser source, which lens is interposed between the latter and the first of two galvanometers moving along rotating optical axes, and which succeed each other on the path of said beam.

  According to another characteristic of this device, it comprises a diode-pumped or diode-pumped YAG type YAG laser source, or a Ytterbium doped fiber type. According to another characteristic of the invention, the operation of the laser source is in relaxed mode with pulses of a few kilowatts. According to yet another characteristic of the invention, the system comprises a plug-in function for exporting three-dimensional decorations from a three-dimensional CAD system to a specific control software designed capable of generating the three-dimensional vectors and to control the parameters of the laser source.

  According to another characteristic, the device comprises a circuit or a specific synchronization card designed able to synchronize the laser instructions and the displacements intended, respectively, to said laser source and servo means, such as electronic cards, axes. optics. Other features of the invention will appear in the description which follows, illustrating a representative mode, in no way limiting, of implementation of the invention.

  This description is illustrated by the single figure, which is a logic diagram showing schematically the interaction of the different control means and the constituent elements of a device for implementing the method. The method according to the invention relates to the laser marking of decorations on flat parts or not, of all materials used in the decorations such as plastics, raw or anodized aluminum, raw or coated metals, wood or raw or coated composites, or similar, the largest dimension can reach several decimetres, and can in particular be greater than one meter. It comprises the following steps: - modeling and generation of three-dimensional polylines in space - generation of three-dimensional vectors - real-time processing of three-dimensional vectors - generation of three-dimensional displacement instructions - management and generation of control parameters of at least one laser source - control of a three-dimensional deflection system.

  The three-dimensional deflection system, in a preferred application, comprises a linear optical axis. The control parameters of the laser source are designed able to act on the power, the frequency, or the hash of this laser source.

  The inventive step of the invention consists in particular in the choice of an architecture to obtain, at the level of the piece to be decorated, a high power density to allow good quality marking. Indeed, the prior art was limited in that, the increase in a focal length necessarily resulting in an increase in the diameter of the spot on the piece to be decorated, and the power density decreasing with distance, it seemed impossible to create, at the level of the piece to be decorated, the conditions of a quality marking. For this purpose, the invention favors the choice of switched lasers, that is to say, driven so as to emit pulses of energy, and to best use the available peak power. This makes it possible to obtain, at the spot, a Gaussian distribution of very sharp energy density, which results in a high concentration of energy on a very small central surface of the spot, and thus allows very high marking. quality and great fineness, even at a distance of about one meter after the beam output galvanometers. The device for implementing such a method comprises a laser source emitting a beam, a linear optical axis constituted by a lens movable in the direction of the beam emitted by this laser source. This lens is interposed between the latter and the first of two mobile galvanometers along rotating optical axes, and which follow one another in the path of the beam. It makes it possible to carry out a defocusing, thus to compensate for the differences in distance when, at the level of the piece to be decorated, one moves away obliquely from the axis of repose of the second galvanometer on the path of the beam. In a preferred application, the operation of the laser source is in relaxed mode with pulses of a few kilowatts. The system is capable of generating three-dimensional patterns to fit non-planar objects. The system allows an adjustment of its operating parameters in order to respond to the variants of aesthetic rendering. The variants are obtained by adjusting the essential parameters of the laser in ranges compatible with the diversity of the cases to be treated. The system makes it possible to import sets, in two or three dimensions, from computer files in standard formats (such as dxf, iges for example), as well as the creation of new patterns. The system allows the creation of part programs, which can be loaded on demand. The system still allows the automation of the execution of part programs, individually or in series. The volume of marking that can be processed by the system is, in a preferred non-restrictive application, of about 1000 mm × 1000 mm × 80 mm. It will be understood in the rest of the following description that what is described for a three-dimensional geometry of decor applies, of course, for a bidirectional geometry of plan decor. A 3D CAD software 1 performs the following functions: creation from a two or three-dimensional file 2, a part plan, and / or import of part or / and two or three-dimensional models; - creation and / or import of two-dimensional or three-dimensional decorations in the form of polylines 3; transformation of the entities to bring the whole of the geometry into the reference of the laser; export of the two-dimensional or three-dimensional decors, via a specific plug-in, to a specific control software 5. A specific control software 5 provides: - the import of 2A format files, in DXF format, 30 composed of polylines 3A in bi or three-dimensional; - the direct import from software 1 of CAD bi or three-dimensional, via the plug-in 4, decors; generation of bi or three-dimensional vectors, describing the geometry of the decorations, and parameterization of the laser 35 (frequency, duration of the laser shots, power).

  The functions of this specific software control 5 still allow the realization of parts programs, the validation of programs and the marking of parts in unit or in small series.

  The specific piloting software 5 manages, again, the backup and the loading with a file 8 part proprietary format. A specific synchronization card 9 synchronizes the laser pointers 10 of the laser 11 and the displacements intended respectively for the laser source and for electronic servocontrol cards for the optical axes X, Y 12 (galvanometer deflection heads 13) and Z 14 (linear optical axis 15 according to the direction of the beam). The X / Y axes 12 and Z 14 guarantee the focusing of the laser beam 16 in the marking volume 17: an X / Y galvanometric head, a combination of two mirrors mounted on galvanometers 13, moves the beam according to X / coordinates Y. A displacement of the X / Y axes alone would make it possible to describe geometries inscribed in a portion of a sphere. A deflection system Z, or linear optical axis 15, moving a lens in an optical assembly, modifies the focusing distance of the laser 11, thus making it possible, in combination with the X and Y axes 12, to describe a geometry three-dimensional in the marking volume 17, or two-dimensional in one of the planes of the volume 17. A machine software 18 automates the tasks of loading and management of a machine dedicated to the marking of large series of parts: - software control specific steering 5 via an automation interface 19. - management 20 and control of the mechanical members of the machine 21 (motorized axis of prepositioning, opening / closing of door ...) - management of series (startup, loading programs, 35 execution of programs ...). - operator interface.

  In a preferred application, four types of laser can be implemented, depending on the types of materials to be decorated. These include: - YVO4 laser, pumped 20W diode, wavelength 1064 nm, average power 20W, stability <± 2%, Gaussian mode, divergence <5 mrad, M2 <2 beam quality, linear polarization, modulation 20 to 200 kHz, pulsating power <780pJ, peak power <130 kW, laser diode excitation, red laser diode pointing laser, wavelength 635nm, power 2mW - YAG laser, pumped 50W diode, wavelength 1064 nm, average power 50W, stability <± 2%, Gaussian mode, divergence <5 mrad, M2 <6 beam quality, circular polarization, 20 to 200 kHz modulation, pulsation energy <2000pJ, peak power <250 kW, laser diode excitation , red laser diode pointing laser, wavelength 635nm, power 2mW - Ytterbium doped fiber 10W, wavelength 1060 at 1070 nm, average power 10W, stability <± 2%, beam quality M2 <1.4, circular polarization, 20 to 100 kHz modulation, pulse energy <500pJ - Ytterbium doped fiber 20W, long Wavelength 1060 to 1070 nm, average power 20W, stability <± 2%, beam quality M2 <1.4, circular polarization, modulation at 100 kHz, pulsation energy <1000 μJ. This list is in no way limitative, but has the advantage of presenting sources that make it possible to obtain high quality results for automobile trim parts in an envelope of 1000x1000x80 mm in particular.

  The X / YZ optical deflection system, for its part, has, in a preferred embodiment, the following characteristics: 8mm beam input diameter, typical 8rad / s processing speed, typical 18 rad / s positioning speed, dimension X / Y field 1000mmmx 1000mmm, defocus range Z ± 40mm, spot diameter function of M2.

  Of course, what is described above with respect to obtaining polyline decorations, also allows the filling operations between such decorations, with the greatest ease.

  The method, as described above, is, again, preferably with higher laser powers, applicable to micro-welding or the like. It will be understood that this process allows the welding of all materials, including plastics.

  Although the invention has been described with respect to a particular embodiment, it is understood that it is in no way limited thereto, and that various modifications of shapes, materials, and combinations can be made therein. of these various elements, without departing from the framework and spirit of the invention.

Claims (10)

  1. A method of laser marking decorations on planar or non-flat parts, of all materials used in decorations such as plastics, raw or anodized aluminum, raw or coated metals, raw or coated wood or composites, or the like, whose larger dimension can reach several decimetres, and can especially be greater than one meter, characterized in that it comprises the steps of: -modeling and generation of three-dimensional polylines (3) in space-generation of three-dimensional vectors (6 real-time processing of the three-dimensional vectors (6) - generation of three-dimensional displacement instructions (12, 14) - management and generation of control parameters (7) of at least one laser source (11) a three-dimensional deflection system (13, 15).   2. Method according to the preceding claim, characterized in that the three-dimensional deflection system comprises a linear optical axis (15).   3. Method according to one of the preceding claims, characterized in that the control parameters (10) of the laser source (11) are designed to act on the power, frequency, or hash of this source. 30   4. Method according to one of the preceding claims, characterized in that the control parameters (10) of the laser source (11) are designed to perform welding operations.   5. Device for implementing a method according to one of the preceding claims, characterized in that it comprises a linear optical axis (15) consisting of a movable lens in the direction (Z) of the beam (16). ) emitted by a laser source (11), which lens is interposed between the latter and the first of two galvanometers (13) movable along rotary optical axes (X, Y), and succeeding one another in the path of said beam (16) .   6. Device according to the preceding claim, characterized in that it comprises a laser source (11) YAG type diode pumped YVO4 or diode pumped YVO4, or fiber-type doped Ytterbium.   7. Device according to one of claims 5 or 6, characterized in that the operation of the laser source (11) is in relaxed mode with pulses of a few kilowatts.   8. Device according to one of claims 5 to 7, characterized in that it comprises a plug-in function 15 (4) for exporting three-dimensional decorations from a three-dimensional CAD system (1) to a specific software control unit (5) adapted to generate the three-dimensional vectors (6) and to drive the parameters (7) of the laser source.   9. Device according to one of claims 5 to 8, characterized in that it comprises a circuit or a specific synchronization card (9) adapted to synchronize the laser instructions (10) and the displacements (12, 14). ) for respectively said laser source (11) and servo means of the optical axes (X, Y, Z), such as electronic cards.   10. Device according to one of claims 5 to 9, characterized in that it comprises a laser source (11) capable of generating the power required for welding work.