DEVICE AND METHOD FOR PRODUCING A THREE-DIMENSIONAL OBJECT

Description

TECHNICAL FIELD

[0001] This is the technical field of selective additive manufacturing. STATE OF THE ART

[0002] Selective additive manufacturing consists of producing three-dimensional objects by consolidating selected areas on successive layers of powdered material (metal powder, ceramic powder, etc.). The consolidated areas correspond to successive sections of the three-dimensional object. Consolidation is carried out, layer by layer, by total or partial selective melting carried out with a consolidation source. This source is typically a radiation source (for example, a high-power laser beam) or a particle beam source (for example, an electron beam - technology known as EBM or "Electron Beam Melting" according to the Anglo-Saxon terminology generally used in the field).

[0003] However, conventional additive manufacturing devices have a productivity that is currently considered insufficient.

[0004] To increase the productivity of additive manufacturing devices, the number of laser sources can be increased. However, this has multiple drawbacks. The efficiency of such a system is limited. The presence of multiple laser sources poses space problems. Furthermore, the multiplication of laser sources is expensive.

[0005] Document US2017173876A1 discloses the preamble of claim 1. PRESENTATION

[0006] One aim of the invention is to overcome at least one of the drawbacks presented above.

[0007] For this purpose, an apparatus according to claim 1 is provided.

[0008] The invention is advantageously supplemented by the characteristics defined in claims 2 to 9, taken alone or in any of their technically possible combinations.

[0009] The invention also relates to a method according to claim 10.

[0010] The invention is advantageously completed by the characteristics of claim 11. DRAWINGS

[0011] Other objectives, characteristics and advantages will appear on reading the following description given for illustrative and non-limiting purposes with reference to the drawings, among which: there Figure 1 schematically represents an apparatus according to an exemplary embodiment of the invention, the Figure 2 represents a perspective view of the device of the Figure 1 , THE Figures 3a , 3b , 3c , 4a and 4brepresent trajectory patterns according to an exemplary embodiment of the invention, the Figure 5 represents a method according to an exemplary embodiment of the invention, DESCRIPTION General structure of the device

[0012] In reference to the figures 1 And 2 , an apparatus 1 is described. The apparatus 1 may be an apparatus 1 for manufacturing an object, for example by additive manufacturing, for example by selective additive manufacturing. The object may be a three-dimensional object.

[0013] The apparatus 1 may comprise a support 140. The support 140 may be adapted to support at least one layer 150 of material, for example of additive manufacturing material. The layer 150 of material may be a layer 150 of powder, for example of additive manufacturing powder.

[0014] The apparatus 1 may comprise a source 110. The source 110 may be a consolidation source. The source 110 may be a radiation source, for example a laser source, for example a laser light source, for example adapted to emit a laser beam.

[0015] The apparatus 1 may comprise a scanning device 130. The scanning device may be adapted to direct the laser beam, for example onto the layer 150, for example so as to scan at least a portion of the layer 150, for example along a scanning path.

[0016] The apparatus 1 comprises a device 120, for example a modulation device 120, for example a scanning trajectory modulation device. The device 120 may be arranged upstream of the scanning device 130. The device 120 may comprise a mirror 121, for example a modulation mirror 121. The mirror 121 may be adapted to reflect the laser beam coming from the laser source and / or direct it towards the scanning device. The angle α of incidence of the laser beam coming from the laser source on the mirror 121 is between 20 and 45°, and / or the angle formed between the laser beam coming from the laser source and directed towards the device 120 and the laser beam coming from the device 120 and directed towards the scanning device 130 is between 40 and 90°.

[0017] Angle of incidence refers to the angle between the direction of propagation of the laser beam and the normal to the mirror at the mirror surface encountered by the laser beam.

[0018] Upstream and downstream means upstream and downstream relative to the direction of the photon flow of the laser beam emitted by the laser source, i.e. relative to the optical path of the laser beam. It is thus possible to modulate the main trajectory defined by the scanning device 130 by means of a prior modulation and to obtain a modulated trajectory.

[0019] Indeed, the modulation of the trajectory makes it possible to improve the energy distribution provided by the laser source, which results in a widening of the melt pool, hence a wider bead of melted material and a reduction in the number of vectors corresponding to the laser paths and consequently an increase in the melt flow rate, i.e. a larger melted surface for the same unit of time. To obtain correct melting, a material needs a quantity of energy per unit of time, called fluence, expressed for example in J / mm 2< . If the fluence is too low, the melting is not complete and the material will not have the expected characteristics. If the fluence is too high, generally in the center of the laser spot, the melt pool will be too dynamic, which will cause unwanted phenomena such as projections, sparks, significant smoke disturbing the laser beam, or bubbling.Such unwanted phenomena degrade the quality of the material obtained. Thus, for a given laser spot diameter, the laser energy and the melting speed, and therefore the productivity, are limited in the prior art. The invention makes it possible to introduce, thanks to a modulation device that does not harm compactness and efficiency, modulations that make it possible to superimpose a secondary trajectory on the powder bed on the main trajectory.

[0020] It is thus possible to overcome the limitations specific to a point laser spot and a rectilinear trajectory by introducing modulations into the trajectory.

[0021] The device thus increases the efficiency of energy transfer to matter. Indeed, since the power of a laser beam is highly localized, the material such as powder melts quickly and the resulting molten pool acts as a mirror for the photons. This results in a significant re-emission of the energy supplied in this setting.

[0022] It is thus possible to obtain a more effective solution while remaining simple to implement and while limiting the associated costs.

[0023] Unlike adding multiple laser sources, it is possible to limit the costs associated with both obtaining the laser sources and the power required to use them.

[0024] The modulation of the trajectory also allows better control of the cooling dynamics of the molten pool and therefore makes it possible to improve the state, in particular the metallurgical state in the case of a metal, of the material formed.

[0025] Modulation also makes it possible, by choosing the modulation pattern, to adjust the quantity of energy deposited over the width of the molten pool, so as to adjust the energy, for example between the edges and the center of the molten pool or between one edge, the center and another edge, so as to limit unwanted phenomena such as projections and / or sparks.

[0026] Furthermore, it is thus possible to obtain an efficient and compact device by the choice of the relative arrangement between the source, the modulation device and the scanning device.

[0027] Indeed, the device is particularly compact compared to a solution with multiple laser sources. The claimed arrangement requires only one laser and is particularly compact without compromising quality in terms of additive manufacturing.

[0028] In particular, such a choice of angle makes it possible to reduce the reflection area and therefore to reduce the dimensions of the modulation mirror and therefore its inertia. It is thus possible to achieve high oscillation frequencies, for example greater than 1.5 kHz, and therefore to increase the efficiency of the modulation device.

[0029] Furthermore, such an apparatus can be obtained by modifying existing apparatuses without requiring extensive modification of the scanning device, for example without interfering with the actuator drive system of the scanning device. Laser source

[0030] The laser source 110 comprises for example a fiber laser, for example a continuous laser for example a single-mode laser with a Gaussian energy distribution.

[0031] The laser beam may have a power greater than or equal to 250 W, for example greater than or equal to 500 W, for example less than or equal to 5000 W, for example less than or equal to 3000 W, for example between 750 and 2500 W, for example equal to 1000 or 2000 W.

[0032] The laser beam may come into contact with the layer 150 of powder, forming a laser spot or spot. The spot may have a given diameter, for example greater than or equal to 50 or 60 µm, for example less than or equal to 300 or 250 µm, for example between 50 and 250 µm, for example equal to 70 or 150 or 250 µm.

[0033] The laser beam used, for example, has a wavelength of 1070 nm.

[0034] The apparatus 1 may comprise an optical element 1101 for controlling the focusing length, for example an optical lens for controlling the focusing length, for example arranged at the output of the laser source. The optical element for controlling the focusing length may be movable so as to adjust the focusing length, for example movable so as to approach and / or move it away from the laser source 110, for example movable along the axis formed by the laser beam 111 exiting the laser source.

[0035] The apparatus 1 may comprise a focusing device 1102 between the optical element for controlling the focusing length, for example arranged between the laser source 110 and the modulation device 120.

[0036] The apparatus 1 may comprise a device for shaping the laser beam, for example so as to homogenize the energy supplied to the surface, for example the upper surface, of the part of the scanned powder layer, for example so as to obtain a top hat or donut type energy distribution. The shaping device may be or comprise a diffractive lens or a refractive element. Scanning device

[0037] The scanning device 130 may comprise a first scanning mirror 131 and / or a second scanning mirror 132. The scanning device 130 may thus be adapted to modify the orientation of the first scanning mirror 131 and / or the second scanning mirror 132 along one or more rotation axes, for example over a range of scanning angle values. The scanning device 130 may be adapted to modify the orientation of the first scanning mirror 131 along a first scanning rotation axis 133, for example over a first scanning angle value range. The scanning device 130 may be adapted to modify the orientation of the second scanning mirror 132 along a second scanning rotation axis 134, for example over a second scanning angle value range.

[0038] The scanning device 130 may be configured to change the orientation of the first scanning mirror 131 along the first scanning rotation axis 133 and / or of the second scanning mirror 132 along the second scanning rotation axis 134, at a scanning rotation speed.

[0039] The first scanning mirror 131 may be adapted and / or controlled to reflect the laser beam 112 from the modulation mirror 121 and direct it toward the second scanning mirror 132. The second scanning mirror 132 may be adapted to reflect the laser beam from the first scanning mirror 131 and direct it onto the layer 150. The system may be adapted to control the orientation of the first scanning mirror 131 along the first scanning rotation axis 133 and of the second mirror 132 along the second scanning rotation axis 134 to control the scanning trajectory of the layer 150 by the laser beam along two degrees of freedom, for example in a plane of the powder layer, for example along two directions of the plane of the powder layer. The plane of the powder layer may be a plane corresponding to a surface, for example an upper surface, of the powder layer.

[0040] The scanning device 130 may comprise at least one actuator, for example for modifying the orientation of the first scanning mirror 131 and / or the second scanning mirror 132. The scanning device 130 may thus comprise a first actuator for modifying the orientation of the first scanning mirror 131 along the first scanning rotation axis 133 and a second actuator for modifying the orientation of the second scanning mirror 132 along the second rotation axis 134.

[0041] The first scanning mirror 131 and / or the second scanning mirror 132 may be a plane mirror, and / or a shaped mirror, for example cut-out shaped, elliptical, or rectangular, for example square, or circular.

[0042] The scanning device 130 may be adapted to impose on the laser beam, or direct the laser beam according to, a scanning trajectory or main trajectory at the level of at least a portion of the layer 150 of additive manufacturing powder. The scanning trajectory or main trajectory corresponds to the trajectory which would be followed by the laser beam in the absence of modulation by the modulation device 120. It therefore corresponds to a certain control of the scanning device 130. The final trajectory therefore depends on the main trajectory and the secondary trajectory as described below.

[0043] The main trajectory may comprise one or more sections, for example rectilinear. The section(s) correspond(s) to portions of trajectory where the beam would actually reach the layer 150 of powder in the absence of modulation, thus forming the spot following the sections. The sections form, for example, vectors.

[0044] The trajectory may comprise one or more jumps separating two sections, corresponding to portions where no laser beam would actually reach the layer 150 of powder in the absence of modulation because at the corresponding moment no laser beam is emitted or reaches the scanning device 130.

[0045] At least two sections, for example two successive sections, can be separated by a spacing, called vector spacing. The successive sections of the main trajectory are for example separated by the same spacing. The spacing is for example greater than 100 µm, for example greater than 200 µm, for example greater than 400 µm, for example less than 1000 µm, for example less than 700 µm, for example equal to 500 µm. The apparatus comprising the modulation device allows an increase in the vector spacing compared to the prior art and therefore greater efficiency by reducing the length of the main trajectory and therefore the manufacturing time.

[0046] The scanning device 130 may comprise a three-axis scanning head. The apparatus 1 may then preferably comprise the optical element for controlling the focal length 1101 and / or the focusing device 1102 described above.

[0047] The scanning device 130 may comprise a two-axis scanning head. The apparatus 1 may then preferably comprise a focusing device between the scanning device 130 and the layer 150. The focusing device comprises for example a lens, for example a flat-field lens, for example an F-Theta lens. Modulation device

[0048] The modulation device 120 may be adapted to modify the orientation of the modulation mirror 121, for example by rotation, for example along at least one rotation axis, over a range of modulation angle values. The modulation device 120 may be adapted to modify the orientation of the modulation mirror 121, for example along a first modulation rotation axis 122, for example over a first range of modulation values. In addition, the modulation device 120 may be adapted to modify the orientation of the modulation mirror 121 along a second modulation rotation axis 123, for example over a second range of modulation values. The first modulation rotation axis 122 and the second modulation rotation axis 123 may be two orthogonal axes.

[0049] The first modulation value range and / or the second modulation value range has for example an amplitude between + / - 0.0025 rad and + / - 0.0015 rad, for example + / - 0.002 rad.

[0050] The range of scanning angle values ​​may be wider than the range of modulation angle values. The first and / or second range(s) of scanning angle values ​​may be wider than the first and / or second range(s) of modulation angle values. Indeed, the modulations aim to modulate the scanning which determines the main trajectory, for example by imposing a secondary trajectory which is superimposed on the main trajectory resulting from the control of the scanning device 130.

[0051] The modulation device 120 may be configured to modify the orientation of the modulation mirror 121 along the first modulation rotation axis 122 and / or the second modulation rotation axis 123, at a modulation rotation speed. The scanning rotation speed may be lower than the modulation rotation speed. Indeed, the modulation device thus makes it possible to offer greater responsiveness.

[0052] The modulation device 120 may comprise at least one actuator, for example to modify the orientation of the modulation mirror 121. The modulation device 120 may thus comprise a first actuator to modify the orientation of the modulation mirror along the first modulation rotation axis 122 and a second actuator to modify the orientation of the modulation mirror along the second modulation rotation axis 123.

[0053] The at least one actuator, for example the first actuator and / or the second actuator, may be or comprise a piezoelectric actuator, for example adapted to oscillate at least at an oscillation frequency greater than or equal to 1 kHz, for example greater than 1.5 kHz, for example greater than 2 kHz, for example less than 15 kHz, for example less than 12 kHz, for example between 1.5 and 10 kHz. Such an actuator makes it possible to achieve high frequencies, while being compact and inexpensive. Furthermore, such an actuator allows high angular precision on the position during modulation, i.e. control of the amplitude, and on the return to a reference position corresponding to an absence of modulation.

[0054] The at least one actuator, for example the first actuator and / or the second actuator, may be or comprise an electromagnetic or mechanical actuator.

[0055] The at least one actuator, for example the first actuator and / or the second actuator, may be or comprise a microelectromechanical system, also called MEMS (microelectromechanical systems), for example adapted to oscillate at least at an oscillation frequency greater than 10 kHz, for example greater than 15 kHz, for example equal to 20 kHz. Such a high modulation frequency makes it possible to increase the main scanning speed while maintaining a satisfactory pattern density on the layer.

[0056] The at least one actuator, for example the first actuator and / or the second actuator, may be or comprise a galvanometer.

[0057] The angle α of incidence of the laser beam coming from the laser source on the mirror 121 may be between 25 and 35°, and / or the angle formed between the laser beam coming from the laser source and directed towards the device 120 and the laser beam coming from the device 120 and directed towards the scanning device 130 may be between 50 and 70°.

[0058] The laser beam may have a diameter between 20 and 40 mm when reflected from the modulation mirror, for example about 23 mm in diameter and / or a diameter between 50 and 100 µm at the surface of the powder layer.

[0059] For an angle of incidence α of 45°, for a laser beam of approximately 30 mm in diameter when reflected on the modulation mirror, the modulation mirror must have an elliptical reflection zone of at least 42 mm in length and 30 mm in width. On the other hand, for an angle of incidence of 30°, the modulation mirror can have an elliptical reflection zone of 35 mm in length and 30 mm in width. The associated mass is therefore reduced by around 18%.

[0060] The angle of incidence of the laser beam from the laser source on the modulation mirror can be between 28 and 32°, for example equal to 30°.

[0061] The modulation mirror 121 may be a mirror, for example a plane mirror, of shape, for example a cut-out shape, elliptical. Such a shape is particularly suitable for limiting the quantity of material, which allows rapid oscillation, without limiting the area that can be reached by the laser on the surface of the powder layer.

[0062] The elliptical mirror has for example a length between D f / cos(α) and 2 D f / cos(α), where D f is the diameter of the laser beam and α the angle of incidence of the laser beam from the laser source on the modulation mirror, for example equal to 1.6 D f / cos(α). The mirror has for example a width between D f and 1.1 D f , for example equal to Df. D f is for example the diameter of the laser beam at 1 / e 2< , or D86 at 86% of the energy of a Gaussian spot.

[0063] Alternatively, the modulation mirror 121 may be a rectangular mirror, for example square, or a circular mirror.

[0064] The modulation mirror 121 may comprise a substrate and a reflection surface coating. Such a coating makes it possible to improve the reflection of photons on the mirror. Such a coating makes it possible to avoid or limit the absorption of the energy of the laser beam by the mirror, avoids or limits the heating of the mirror, the heating leading to deformation and reducing the quality of the beam. Such a coating thus makes it possible to increase the lifetime of the modulation mirror. The modulation mirror 121 comprises for example silicon carbide. The mirror comprises for example a substrate, the substrate being for example made of silicon carbide and / or is essentially made of silicon carbide. Silicon carbide offers good performance in terms of mass / rigidity, without having disadvantages specific to materials such as berylium, for example toxicity and difficulty of supply, as well as the cost of supply.It is thus possible to further reduce the mass and therefore the inertia of the modulation mirror, and therefore to further increase the oscillation frequency of the actuator(s) of the modulation device 120.

[0065] The modulation device 120 can be adapted to modulate the trajectory according to a modulation. The modulation device 120 can thus be adapted to impose on the laser beam, or direct the laser beam according to, a modulation trajectory or secondary trajectory which is superimposed on the main trajectory at the level of at least a portion of the layer 150 of additive manufacturing powder.

[0066] The modulation mirror 121 can be adapted to oscillate, for example along at least one axis, for example along two axes, for example along the first modulation rotation axis 122 and / or along the second modulation rotation axis 123. The modulation mirror 121 can thus be adapted to oscillate simultaneously and / or independently along the two axes, for example along the first modulation rotation axis 122 and / or along the second modulation rotation axis 123.

[0067] The modulation mirror 121 can thus be adapted to oscillate according to first oscillations according to the first modulation rotation axis 122 and / or according to second oscillations according to the second modulation rotation axis 123. The modulation mirror 121 can be adapted to oscillate simultaneously according to first oscillations according to the first modulation rotation axis 122 and according to second oscillations according to the second modulation rotation axis 123, for example to generate a sinusoidal or circular pattern. The oscillations according to the first modulation rotation axis 122 and / or according to the second modulation rotation axis 123 can be controlled in amplitude and / or in frequency, for example independently between the two axes 122 and 123.

[0068] The oscillations along the first modulation rotation axis 122 can be controlled so as to have a phase shift relative to the oscillations along the second rotation axis 123. Controlling the phase shift makes it possible, for example, to adjust the shape of the pattern, to change the shape of the pattern and / or to orient the pattern along the scanning direction.

[0069] The oscillations allow for example resulting oscillations, for example specific to the secondary trajectory, at the level of the layer 150 of powder, of amplitude greater than 100 µm, for example greater than 200 µm, for example less than 2000 µm, for example less than 1000 µm, for example less than 750 µm, for example equal to 500 µm. The oscillations can allow to increase the width of the melt pool for the same speed of movement of the spot and the same fluence. It is thus possible to increase the vector spacing and therefore the surface productivity proportionally.

[0070] The modulation mirror may be adapted to oscillate at a frequency greater than 1.5 kHz, preferably greater than 2.5 kHz, preferably greater than or equal to 10 kHz, for example along the first modulation rotation axis 122 and / or the second modulation rotation axis 123. The modulation may comprise a pattern, for example a periodic pattern, for example repeated at a frequency greater than 1.5 kHz, preferably greater than 2.5 kHz, preferably greater than or equal to 10 kHz. The pattern is for example an oscillation. The modulation may form a pattern. It is thus possible, using the modulation device, to introduce modulations.

[0071] The secondary trajectory may include a pattern, for example so as to superimpose a pattern on the primary trajectory at the surface of the powder layer portion.

[0072] In reference to the Figures 3a to 3c , an example pattern is shown. The pattern is a sinusoid.

[0073] On the Figure 3a , the elements in bold represent the main trajectory comprising sections 301 separated by a gap 303 and jumps 302, while the elements in thin lines represent the modulated trajectory after superposition of the secondary trajectory so as to present sinusoidal oscillations and traveled by the laser spot 304.

[0074] On the Figure 3b , the corresponding secondary or modulation trajectory is represented as a variation along an axis as a function of time.

[0075] There Figure 3c details the secondary trajectory between the control associated with the first modulation rotation axis 305 and the control associated with the second modulation rotation axis 306, as a function of time. In the example, the modulation mirror oscillates only around the second modulation rotation axis.

[0076] In reference to the Figures 4a and 4b, an example pattern is shown. The pattern is circular.

[0077] On the Figure 4a , the corresponding secondary or modulation trajectory is represented as a variation along an axis as a function of time.

[0078] There Figure 4b details the secondary trajectory between the control associated with the first modulation rotation axis 405 and the control associated with the second modulation rotation axis 406, as a function of time. In the example, the modulation mirror oscillates both around the first modulation rotation axis and around the second modulation rotation axis.

[0079] The laser source 110, the modulation device 120 and the scanning device 130 are for example arranged so as to allow a surface melting rate, that is to say the surface of the powder layer covered by the laser spot per unit of time, greater than 1000 cm 2 < / min, for example greater than 2000 cm 2 < / min, for example greater than 4000 cm 2 < / min, for example less than 15000 cm 2 < / min, for example less than 10000 cm 2 < / min, for example of the order of 6000 cm 2 < / min. The apparatus according to the invention, due to the presence of the modulation device, allows a drastic increase in the surface melting rate and therefore in the surface productivity.

[0080] The modulation device 120 and the scanning device 130 are for example arranged so as to allow the speed of movement of the laser spot to be between 0.5 and 10 m / s, for example between 1 and 5 m / s, for example equal to 1 or 2 m / s.

[0081] The modulation mirror 121 may be arranged at a converging portion of the laser beam coming from the laser source 110, for example downstream of the focusing device 1102 when the scanning device 130 comprises a three-axis scanning head. It is thus possible to limit the disturbance of the quality of the laser beam. Indeed, the laser beam at the output of the optical element for controlling the focusing length 1101 is divergent and only becomes convergent at the output of the focusing device 1102. Placing the modulation device 120 elsewhere, in particular further upstream, would risk disturbing the optical operation by decentering the laser beam. Layer and support

[0082] The support includes, for example, a tray designed to be moved as layers are added.

[0083] The or each layer 150 of powder has for example a thickness of between 10 and 100 µm, for example between 20 and 60 µm, for example equal to 40 µm.

[0084] The material of the or each layer 150 of powder has for example a fluence of between 0.5 and 10 J / mm 2< , for example of between 1 and 5 J / mm 2< , for example equal to 2 J / mm 2< .

[0085] The material of the or each powder layer 150 may comprise titanium and / or aluminum and / or inconel and / or stainless steel and / or maraging steel. The material of the or each powder layer 150 may consist of titanium and / or aluminum and / or inconel and / or stainless steel and / or maraging steel. Other source

[0086] In addition to the laser source 110, the apparatus may comprise a second source. The second source may be a particle beam source, for example an electron beam, for example an EBM source (“Electron Beam Melting” according to the English terminology generally used in the field), for example an electron gun.

[0087] The apparatus 1 may thus be a hybrid apparatus, comprising several energy sources for carrying out selective fusion. The second source may form a primary energy source suitable for carrying out selective fusion at the core of the object. The laser source 110 may form a secondary energy source suitable for carrying out selective fusion at peripheral areas, for example the skin or edge of the object.

[0088] In this way, it is possible to obtain an object with different mechanical or metallographic properties at its periphery and in its volume.

[0089] The apparatus 1 may further comprise one or more other laser sources 110, for example such as the laser source described above. One or more other laser sources 110, for example each other laser source 110, may be equipped with a scanning device 130, for example a scanning device 130 as described above, and / or a modulation device 120, for example a modulation device 120 as described above. It is thus possible to manufacture large parts via a support and large powder layers, by implementing several laser sources and / or scanning devices and / or modulation devices in parallel to treat different areas of the powder layer or layers. Means of ordering

[0090] The apparatus 1 may comprise control means adapted to control the apparatus, for example to control the laser source 110 and / or the modulation device 120 and / or the scanning device 130.

[0091] The control means comprise or form, for example, a control unit.

[0092] The control means comprise, for example, data storage means, for example a data storage unit, for example a random access memory and / or a read only memory. The storage means may be adapted to store instructions corresponding to the method described below.

[0093] The control means include, for example, computing means, for example a processor.

[0094] The control means may be configured to implement a method as described below. Process

[0095] In reference to the Figure 5, a method of manufacturing a three-dimensional object by selective additive manufacturing is described.

[0096] The method can be implemented by means of the apparatus 1.

[0097] The method may comprise a step 400 of controlling the scanning device 130 according to a command to scan at least a portion of the layer 150 of additive manufacturing powder according to the scanning trajectory or main trajectory.

[0098] The method may comprise a step 402, implemented at the same time as the control of the scanning device of step 400, of controlling the modulation device 120 according to a modulation command of the scanning trajectory. The modulation command of the scanning trajectory corresponds for example to the secondary trajectory or modulation trajectory.

[0099] Steps 400 and 402 may be implemented such that the laser beam follows a modulated scanning path at the powder layer 150. The modulated scanning path may correspond to the superposition of the modulation path on the scanning path.

[0100] In step 400 of controlling the scanning device 130, the scanning device can be controlled so as to modify the orientation of the first scanning mirror 131 and / or the second scanning mirror 132 along the second scanning rotation axis 134 at a scanning rotation speed. In step 402 of controlling the modulation device 120, the modulation device 120 can be controlled so as to modify the orientation of the modulation mirror 121 along the first rotation axis and / or second rotation axis(es), respectively 122 and / or 123, of modulation at the modulation rotation speed. The scanning rotation speed can be lower than the modulation rotation speed. Detailed examples

[0101] For a spot diameter of 70 µm, a spot displacement speed of 2 m / s, a layer thickness of 40 µm, a fluence of 2 J / mm 2< , an exemplary apparatus according to the prior art without the modulation device 120 would require a spacing of 50 µm and would be limited to a laser power of 200 W, so that it would achieve a surface melting rate of 600 cm 2< / min, whereas an exemplary apparatus such as the apparatus described, which includes the modulation device 120, can for example allow a spacing of 500 µm and a secondary trajectory oscillation width of 500 µm, and exploit a higher laser power, for example from 1000 to 2000 W, allowing a surface melting rate of 3000 to 6000 cm 2< / min and a surface productivity thus improved by a ratio of 5 to 10.

Claims

1. Apparatus for manufacturing a three-dimensional object by selective additive manufacturing, comprising: - a substrate (140) suitable for supporting at least one layer (150) of additive manufacturing powder, - a laser source (110) suitable for emitting a laser beam (111), - a scanning device (130) suitable for directing the laser beam onto the powder layer so as to scan at least part of the powder layer, - a scanning path modulation device (120) arranged upstream of the scanning device, the modulation device comprising a modulation mirror (121) suitable for reflecting the laser beam from the laser source and directing it towards the scanning device, characterized in that the angle of incidence of the laser beam from the laser source on the modulation mirror is between 20 and 45°, and in that the modulation device (120) is suitable for changing the orientation of the modulation mirror along a first modulation rotational axis (122) and along a second modulation rotational axis (123).

2. Apparatus according to claim 1, wherein the scanning device (130) comprises a first scanning mirror (131) and / or a second scanning mirror (132), the scanning device being suitable for changing the orientation of the first scanning mirror along a first scanning rotational axis (133) and / or of the second scanning mirror along a second scanning rotational axis (134).

3. Apparatus according to claim 2, wherein the scanning device is suitable for changing the orientation of the first scanning mirror (131) along the first scanning rotational axis (133) over a first range of scanning angle values and / or of the second scanning mirror (132) along the second scanning rotational axis (134) over a second range of scanning angle values, wherein the modulation device (120) is suitable for changing the orientation of the modulation mirror along the first modulation rotational axis (122) over a first range of modulation angle values and the second modulation rotational axis (123) over a second range of modulation angle values, the first and / or second range(s) of scanning angle values being wider than the first and / or second range(s) of modulation angle values.

4. Apparatus according to either claim 2 or claim 3, wherein the scanning device (130) is designed to change the orientation of the first scanning mirror (131) along the first scanning rotational axis (133) and / or of the second scanning mirror (132) along the second scanning rotational axis (134), at a scanning rotational speed, wherein the modulation device (120) is designed to change the orientation of the modulation mirror (121) along the first modulation rotational axis (122) and the second modulation rotational axis (123) at a modulation rotational speed, the scanning rotational speed being lower than the modulation rotational speed.

5. Apparatus according to any of claims 2 to 4, wherein the scanning device comprises the first scanning mirror (131) and the second scanning mirror (132), the first scanning mirror being suitable for reflecting the laser beam from the modulation mirror (121) and directing it towards the second scanning mirror, the second scanning mirror being suitable for reflecting the laser beam from the first scanning mirror and directing it onto the additive manufacturing powder layer (150), the system being suitable for controlling the orientation of the first scanning mirror along the first scanning rotational axis and of the second mirror along the second scanning rotational axis in order to control the path for the scanning of the powder layer by the laser beam according to two degrees of freedom in a plane of the powder layer.

6. Apparatus according to any of claims 1 to 5, wherein the modulation device (120) is suitable for modulating the path according to a modulation comprising an oscillation at a frequency greater than 1.5 kHz, preferably greater than or equal to 10 kHz.

7. Apparatus according to any of claims 1 to 6, wherein the angle of incidence of the laser beam from the laser source on the modulation mirror is between 25 and 35°.

8. Apparatus according to any of claims 1 to 7, wherein the modulation mirror (121) comprises silicon carbide.

9. Apparatus according to any of claims 1 to 8, wherein the modulation mirror (121) is an elliptically shaped mirror.

10. Method for manufacturing a three-dimensional object by selective additive manufacturing, implemented by means of the apparatus according to any of the preceding claims, comprising the following steps: - controlling the scanning device (130) according to a command for scanning at least part of the additive manufacturing powder layer (150) along a scanning path, and - at the same time as controlling the scanning device, controlling the modulation device (120) according to a scanning path modulation command, so that the laser beam follows a modulated scanning path over the powder layer (150).

11. Method according to claim 10, wherein: - in the step of controlling the modulation device (120), the modulation device is controlled so as to change the orientation of the modulation mirror (121) along the first and / or second modulation rotational axis(es) (122, 123) at a modulation rotational speed, - in the step of controlling the scanning device (130), the scanning device is controlled so as to change the orientation of the first scanning mirror (131) along the first scanning rotational axis (133) and / or of the second scanning mirror (132) along the second scanning rotational axis (134), at a scanning rotational speed lower than the modulation rotational speed.