Apparatus for producing three-dimensional work piece

Abstract

To provide an apparatus for producing a three-dimensional work piece.SOLUTION: An apparatus 10 for producing a three-dimensional work piece 46 by irradiating layers of a raw material powder with electromagnetic or particle radiation comprises a process chamber 16 accommodating a carrier 12 and a powder application device 14 for applying a layer of raw material powder onto the carrier 12. The apparatus 10 further comprises an irradiation unit 26 for selectively irradiating the layer of raw material powder with electromagnetic or particle radiation in accordance with a geometry of a corresponding layer of the work piece 18 to be produced. An absorption device 50 which is adapted to absorb heat radiation emitted upon selectively irradiating the layer of raw material powder with electromagnetic or particle radiation is provided in the process chamber 16 and / or in the irradiation unit 26 at such a position that it is capable of absorbing radiation occurring in an interior of the process chamber 16 and / or in an interior of the irradiation unit 26.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an apparatus for producing three-dimensional workpieces by irradiating a layer of raw material powder with electromagnetic or particle radiation. [Background technology]

[0002] Powder bed fusion is an additive manufacturing method that can process powders, particularly metal and / or ceramic raw materials, into three-dimensional workpieces with complex shapes. To do this, a layer of raw powder is applied to a carrier and selectively irradiated with a laser depending on the desired shape of the workpiece to be manufactured. The laser beam penetrating the powder layer causes heating, resulting in melting or sintering of the raw powder particles. Additional layers of raw powder are then applied successively to the previously laser-treated carrier layer until the workpiece has the desired shape and size. Powder bed fusion may be employed to manufacture or repair prototypes, tools, replacement parts, high-value components, or medical prostheses, such as dental or orthopedic prostheses, based on CAD data.

[0003] An exemplary apparatus for producing three-dimensional workpieces by powder bed fusion, as described in EP 3321003, includes a process chamber containing a carrier for receiving raw material powder. An irradiation unit including a radiation source and a plurality of optical elements is provided to selectively irradiate the raw material powder on the carrier with electromagnetic or particle radiation to produce the workpiece. A protective gas flow is directed through the process chamber to establish a desired atmosphere within the process chamber and to evacuate impurities from the process chamber.

[0004] As a three-dimensional workpiece is built on a carrier in a powder bed fusion apparatus, radiant energy is introduced into the raw material powder, causing it to melt and / or sinter. Specifically, a molten pool of molten material is generated in the area where the radiation beam strikes the raw material powder. Thermal radiation emitted from the irradiated powder bed causes a temperature increase in the processing chamber, which can then cause a temperature increase in the irradiation unit.

[0005] As described in EP 3067132 A1, temperature changes in the irradiation unit can cause temperature-dependent changes in certain optical properties of optical elements of the irradiation unit. For example, the refractive index of an optical fiber, a lens or another optical element, or the shape of the lens, in particular the curvature or radius, can change depending on the temperature prevailing in the process chamber and thus in the irradiation unit. Temperature-induced changes in the optical properties of the optical elements can cause the focal position of the radiation beam to move along the beam path of the radiation beam. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] European Patent No. 3321003 [Patent Document 2] European Patent Application Publication No. 3067132 Summary of the Invention [Problem to be solved by the invention]

[0007] It is an object of the present invention to provide an apparatus for producing high quality three-dimensional workpieces by irradiating a layer of raw material powder with electromagnetic or particle radiation. [Means for solving the problem]

[0008] An apparatus for manufacturing a three-dimensional workpiece by irradiating a layer of raw material powder with electromagnetic or particle radiation includes a processing chamber that accommodates a carrier. The apparatus further includes a powder application device for applying the layer of raw material powder onto the carrier. The powder application device may be movable across the carrier to distribute the raw material powder layer on the surface of the carrier. The carrier may be a rigidly fixed carrier. However, the carrier is preferably designed to be vertically movable, so that the carrier can move vertically downward as the workpiece increases in build height as it is built up layer by layer from the raw material powder. The raw material powder applied to the carrier is preferably a metal powder, in particular a metal alloy powder, but may also be a ceramic powder or a powder containing a different material. The powder may have any suitable particle size or particle size distribution. However, it is preferred to process powders with a particle size of less than 100 μm. The processing chamber is preferably sealable from the ambient atmosphere.

[0009] The apparatus further comprises an irradiation unit for selectively irradiating the raw material powder layer with electromagnetic or particle radiation according to the shape of the corresponding layer of the workpiece to be produced. The irradiation unit for selectively irradiating the raw material powder layer with electromagnetic or particle radiation may comprise a radiation beam source, in particular a laser beam source, and may further comprise at least one optical unit for splitting, directing and / or processing at least one radiation beam emitted from the radiation beam source. The optical unit may comprise optical elements such as an objective lens and a scanner unit, the scanner unit preferably comprising a diffractive optical element and a deflection mirror. The irradiation unit may irradiate the raw material powder layer with a single radiation beam. However, it is also conceivable that the irradiation system irradiates the raw material powder layer with two or more radiation beams.

[0010] An absorber configured to absorb radiation is provided in the treatment chamber and / or the irradiation unit in a position such that it can absorb radiation generated in the treatment chamber and / or the irradiation unit. An "absorber" in the sense of the present application is a device that absorbs radiation, in particular thermal radiation, electromagnetic radiation and / or particle radiation, and thus emits said radiation from components arranged in the vicinity of the absorber. The thermal radiation absorbed by the absorber may be emitted from the powder bed, the construction part of the workpiece, the heating unit, and further from the heated components. The electromagnetic radiation and / or particle radiation absorbed by the absorber may be radiation emitted to irradiate a layer of raw material powder. The electromagnetic radiation and / or particle radiation may be reflected, in particular, from the powder bed formed by a layer of raw material powder applied on a carrier.

[0011] The phrase "in the processing chamber and / or in the irradiation unit" may refer to the placement of the absorber within the interior space of the processing chamber and / or the irradiation unit and / or to the integration of at least a portion of the absorber within a component of the processing chamber and / or the irradiation unit. For example, the absorber may be at least partially integrated into a wall of the processing chamber and / or the irradiation unit or the absorber may be at least partially disposed in an opening in a wall of the processing chamber and / or the irradiation unit. The absorber may also be at least partially integrated into a component of an apparatus for manufacturing three-dimensional workpieces that is disposed within the processing chamber and / or the irradiation unit.

[0012] The absorber may be formed by a single absorber element which may be arranged in the treatment chamber or in the irradiation unit, however, it is also conceivable that the absorber comprises a plurality of absorber elements which may be distributed in the treatment chamber and / or in the irradiation unit.

[0013] The absorber absorbs radiation that would otherwise heat the optical elements of the irradiation unit. As a result, the absorber attenuates or even prevents temperature-induced changes in the optical properties of the optical elements of the irradiation unit, as well as dislocations due to thermal distortion. This may reduce or even prevent undesired movements of the focal position of the radiation beam along the beam path of the radiation beam, i.e., movements of the focal position in the z-axis direction. Similarly, undesired movements of the spot position of the radiation beam, i.e., movements of the spot position in the x-axis and / or y-axis directions, may be reduced or even prevented. This allows for the production of high-quality workpieces that are less affected or even not affected at all by the temperature-induced focal position movements.

[0014] The absorbing surface of the absorber may face the interior of the processing chamber and / or the interior of the irradiation unit, so that the absorber can particularly effectively absorb radiation generated inside the processing chamber and / or inside the irradiation unit.

[0015] The absorbing surface of the absorber may have a hemispherical reflectivity of less than 40%, preferably less than 20%, more preferably less than 10%, and most preferably less than 5% for thermal radiation, i.e., radiant energy in the wavelength range from 0.75 μm to 50 μm. Alternatively or additionally, the absorbing surface of the absorber may have a hemispherical reflectivity of less than 40%, preferably less than 20%, more preferably less than 10%, and most preferably less than 5% for radiant energy at wavelengths of electromagnetic or particle radiation used to selectively irradiate the layer of raw material powder, in particular at wavelengths in the ranges of 350 nm to 1100 nm, preferably 405 to 490 nm (blue), 490 to 575 nm (green), and / or 805 to 1100 nm (infrared).

[0016] Alternatively or additionally, the absorbing surface of the absorber may be at least partially anodized, coated, foiled, oxidized, structured, and / or roughened, in particular laser black marked. The anodized absorbing surface layer may have a thickness of 0.5 μm to 150 μm. The absorbing coating provided on the absorber and forming the absorbing surface of the absorber may be a black and / or opaque coating or foil, such as a black metal or black ceramic coating or foil, and / or may have a thickness of 0.1 μm to 1 mm. The surface roughness of the absorbing surface may be in the range of 0.1 μm to 10 μm.

[0017] However, the various absorbing surfaces may also have different hemispherical reflectivities, and in particular, the hemispherical reflectivity of the absorbing surfaces in the processing chamber may differ from that of the absorbing surfaces in the irradiation unit. Preferably, the absorbing surfaces of the absorbing device arranged in the processing chamber are good absorbers of radiant energy at the wavelengths of the electromagnetic or particle radiation used to selectively irradiate the layer of raw material powder, i.e., the radiant energy at the wavelengths emitted by the radiation source of the irradiation unit. Additionally or alternatively, the absorbing surfaces of the absorbing units arranged in the irradiation units may be good absorbers of thermal radiation, i.e., radiation with wavelengths in the range of 0.75 μm to 50 μm.

[0018] It is also conceivable that the absorber or the absorbing surface of the absorber comprises or is made of a semi-transparent material that absorbs radiant energy at the wavelength of electromagnetic or particle radiation, in particular laser radiation, used to selectively irradiate the layer of raw material powder. For example, the absorbing surface of the absorber may comprise or be made of mineral glass or acrylic glass. The absorbing surface of the absorber may also be covered by a semi-transparent window made of a non-absorbing material. A cooling channel may be formed between the absorbing surface and the semi-transparent window. A coolant, which may be, for example, an absorbent coolant such as water, may flow through the cooling channel.

[0019] A reflecting device configured to reflect radiation may be provided in the processing chamber and / or the irradiation unit in a position such that it can reflect radiation generated inside the processing chamber and / or inside the irradiation unit. A "reflecting device" in the sense of the present application is a device that reflects radiation, in particular thermal, electromagnetic and / or particle radiation, and thus deflects said radiation away from components arranged in the vicinity of the reflecting device. The reflecting device may be formed by a single reflecting element that may be arranged in the processing chamber or in the irradiation unit. However, it is also conceivable for the reflecting device to comprise multiple reflecting elements that may be distributed inside the processing chamber and / or in the irradiation unit.

[0020] The reflecting device may be provided in particular in areas of the treatment chamber and / or irradiation unit where, during selective irradiation of the raw material powder layer with electromagnetic or particle radiation, emitted or reflected thermal radiation, electromagnetic radiation, and / or particle radiation may strongly affect the optical properties of optical elements of the irradiation unit or may cause severe deformation due to intense heating. Furthermore, the reflecting device may be arranged to reflect the thermal radiation, electromagnetic radiation, and / or particle radiation into areas of the treatment chamber and / or irradiation unit where the radiation is less destructive and / or can be more easily removed. For example, the reflecting device may be provided in an area of ​​the treatment chamber arranged adjacent to the irradiation unit so as to reflect the radiation away from the irradiation unit and towards a carrier supporting the raw material powder layer to be irradiated.

[0021] The reflecting surface of the reflecting device may face the interior of the processing chamber and / or the interior of the irradiation unit, so that the reflecting device can particularly effectively reflect radiation generated inside the processing chamber and / or inside the irradiation unit.

[0022] The reflective surface of the reflector may have a hemispherical reflectivity of greater than 60%, preferably greater than 70%, more preferably greater than 80%, and most preferably greater than 90% for thermal radiation, i.e., radiant energy in the wavelength range from 0.75 μm to 50 μm. Alternatively or additionally, the reflective surface of the reflector may have a hemispherical reflectivity of greater than 60%, preferably greater than 70%, more preferably greater than 80%, and most preferably greater than 90% for radiant energy at wavelengths of electromagnetic or particle radiation used to selectively irradiate the layer of raw material powder, particularly at wavelengths of 350 nm to 1100 nm, preferably 405 to 490 nm (blue), 490 to 575 nm (green), and / or 805 to 1100 nm (infrared).

[0023] Alternatively or additionally, the reflective surface of the reflector device may be at least partially structured, foiled, coated, and / or polished. The reflective coating or foil provided on the reflector device and forming the reflective surface of the reflector device may be specular and / or diffusely reflective. The reflective surface of the reflector device may be formed by a white opaque coating or white opaque foil and / or may have a thickness of 0.01 μm to 1 mm. The surface roughness of the reflective surface may be less than 1 μm, preferably less than 0.2 μm.

[0024] However, it is also contemplated that the various reflective surfaces may have different hemispherical reflectivities, and in particular, that the hemispherical reflectivity of the reflective surfaces in the processing chamber may differ from that of the reflective surfaces in the irradiation unit. Preferably, the reflective surface of the reflector disposed in the processing chamber is a good reflector of radiant energy at the wavelengths of the electromagnetic or particle radiation used to selectively irradiate the layer of raw material powder, i.e., the radiant energy at the wavelengths emitted from the radiation source of the irradiation unit. Additionally or alternatively, the reflective surface of the reflector disposed in the irradiation unit may be a good reflector of thermal radiation, i.e., radiation with wavelengths in the range of 0.75 μm to 50 μm. The reflective surfaces in the processing chamber may also have retroreflective properties, for example, the reflective surfaces may comprise retroreflective foil.

[0025] At least one of the absorber and reflector may contain a material with a thermal conductivity of at least 10 W / (m*K), preferably at least 50 W / (m*K), more preferably at least 100 W / (m*K), to ensure sufficient dissipation of heat from the absorber and / or reflector.

[0026] In addition to the thermal conductivity of the absorber and reflector, the distance between the absorbing and reflecting surfaces, respectively, and the elements serving to emit energy from the absorber and reflector, respectively, may be appropriately customized. The absorber and reflector, respectively, may be made of a different material than the elements serving to emit energy from the absorber and reflector, respectively. In particular, the length of the emission path of the radiant energy and the thermal resistance along this emission path must be minimized, since the temperature difference between the heat source and the heat exhaust pipe depends on the overall effect of the heat flow and its assistance along the emission path.

[0027] The absorber may comprise at least one discrete absorbing element located within the processing chamber and / or within the irradiation unit and serving the sole purpose of absorbing radiation emitted and / or reflected during selective irradiation of the layer of raw material powder with electromagnetic or particle radiation. For example, the absorber may comprise at least one plate-shaped absorbing element with a suitable absorbing surface.

[0028] Alternatively or additionally, the reflecting device may comprise at least one separate reflecting element disposed within the processing chamber and / or irradiation unit and serving the sole purpose of reflecting radiation emitted and / or reflected during selective irradiation of the layer of raw material powder with electromagnetic or particle radiation. For example, the reflecting device may comprise at least one plate-shaped reflecting element with a suitable reflecting surface.

[0029] Alternatively or additionally, the absorber may comprise at least one absorbing element formed by a portion of the processing chamber wall and / or a portion of the irradiation unit housing wall, for example, the absorber may comprise at least one absorbing element formed by a portion of the processing chamber wall and / or a portion of the irradiation unit housing wall and provided with an anodized, coated and / or roughened surface forming an absorbing surface.

[0030] Furthermore, the reflector may comprise at least one reflecting element formed by a portion of a processing chamber wall and / or a portion of an irradiation unit housing wall. For example, the reflector may comprise at least one reflecting element formed by a portion of a processing chamber wall, a portion of a support structure of the irradiation unit and / or a portion of an irradiation unit housing wall, the reflecting element being provided with a coated and / or polished surface forming a reflective surface.

[0031] The apparatus may further comprise a transmission element for transmitting the electromagnetic radiation or particle radiation emitted by the irradiation device into the processing chamber. The transmission element may, for example, be designed in the form of a window. Alternatively, the transmission element may comprise or consist of an optical element of the irradiation device, in particular a lens. The transmission element may be arranged in a wall of the processing chamber, in particular in the upper wall portion of the processing chamber. In a particularly preferred embodiment of the apparatus, the transmission element is arranged in an area above the center of the carrier. For example, the transmission element may be integrated into a wall portion of the processing chamber, in particular in the upper wall portion.

[0032] The material of the transmission element may be selected depending on the type of radiation emitted by the irradiation device to ensure the desired transparency of the transmission element to the electromagnetic or particle radiation emitted by the irradiation device. For example, the transmission element may be made of a glass material or a suitable polymer material. If necessary, the transmission element in the region of its surface facing the interior of the processing chamber may be provided with a surface layer that minimizes adhesion and deposition of welding fume condensate on the surface of the transmission element. In a particularly preferred embodiment of the device, the transmission element is accommodated in a portion of the processing chamber wall that forms at least the reflecting element of the reflecting device. The processing chamber wall portion may, for example, be an upper wall portion of the processing chamber.

[0033] The transmission element may be provided with a surface structure and / or coating on one or more surfaces, in particular its entrance and / or exit surfaces. In a preferred embodiment, the transmission element may be provided with an anti-reflective coating on its entrance surface, meaning the surface facing away from the processing chamber. Additionally or alternatively, the transmission element may be provided with a reflective coating on its exit surface, meaning the surface facing the processing chamber, to prevent excessive heating of the transmission element. The reflective coating on the exit surface of the transmission element may have a reflectivity of more than 40%, preferably more than 50%, and even more preferably more than 60%, for radiant energy in the wavelength range of 0.75 μm to 50 μm. In a further preferred embodiment, the transmission element (optionally comprising the coated surface and / or the structured surface) is configured to transmit at least 70%, in particular at least 90%, in the direction from the entrance surface to the exit surface of radiation of the wavelengths of the electromagnetic or particle radiation used to selectively irradiate the layer of raw material powder, i.e. radiation of the wavelengths emitted by the radiation source of the irradiation unit, in particular radiation of wavelengths in the ranges of 350 nm to 1100 nm, in particular 405 to 490 nm (blue), 490 to 575 nm (green) and / or 805 to 1100 nm (infrared).

[0034] In certain preferred embodiments of the apparatus, all applicable process chamber wall portions that receive the thermal radiation emitted during selective irradiation of the layer of raw material powder with electromagnetic or particle radiation form either an absorber or a reflector. The term "applicable process chamber wall portion" in this context refers to a process chamber wall portion that does not perform another functional purpose, e.g., does not perform the introduction of gas into or the exhaust of gas from the process chamber, making the process chamber wall portion unsuitable for forming an absorber or a reflector.

[0035] In a preferred embodiment of the apparatus, the processing chamber comprises a first gas inlet for introducing a gas, particularly an inert gas, into the processing chamber. For example, the first gas inlet may be formed by an opening in a porous processing chamber wall portion and / or a processing chamber wall portion, particularly a processing chamber sidewall portion. The gas may be provided by a first gas source, which may comprise a first gas storage container and a first gas supply line. The first gas source may be, for example, an argon gas source or a nitrogen gas source. The first gas supply line may be connected to the first gas inlet. The processing chamber may further comprise a first gas outlet for exhausting the gas from the processing chamber.

[0036] The gas stream introduced into the processing chamber through the first gas inlet and exhausted from the processing chamber through the first gas outlet may absorb and entrap particulate impurities such as soot, welding fumes, and dust as it is directed through the processing chamber, particularly across the carrier, and exhaust such particulate impurities from the processing chamber. The first gas outlet and the first gas inlet may be connected to a recirculation line for recirculating the gas exiting the processing chamber through the first gas outlet back into the processing chamber through the first gas inlet. A suitable filtration device may be disposed in the recirculation line for filtering particulate impurities from the gas stream.

[0037] The first gas inlet may be configured to direct at least a portion of the gas flow introduced into the processing chamber through the first gas inlet toward an absorber and / or reflector disposed within the processing chamber to transfer heat from the absorber and / or reflector to the gas flow. Thus, the gas flow may be used to cool the absorber and / or reflector. The first gas source may be configured to provide a cooling gas or a heating gas. For this purpose, the first gas source may be in thermal contact with a first temperature control system configured to transfer heat to or evacuate heat from the gas introduced into the processing chamber.

[0038] The first temperature control system preferably operates to cool the gas introduced into the process chamber while the apparatus and irradiation unit are operating to produce the three-dimensional workpiece by irradiating the layer of raw material powder with electromagnetic or particle radiation. Conversely, during a start-up phase of the apparatus before starting the irradiation unit and before starting production of the three-dimensional workpiece, the first temperature control system may operate to heat the gas introduced into the process chamber in order to heat the process chamber and components of the apparatus in thermal contact with the process chamber to a suitable operating temperature.

[0039] Preferably, the irradiation unit comprises a second gas inlet for introducing gas, particularly an inert gas, into the irradiation unit. The gas may be provided by a second gas source, which may comprise a second gas storage container and a second gas supply line. The second gas source may, for example, be a gas source that supplies a gas with a high heat transfer coefficient without increasing the flow rate. In particular, the second gas source may be a helium gas source. The second gas supply line may be connected to the second gas inlet. The irradiation unit may further comprise a second gas outlet for discharging gas from the irradiation unit. The second gas outlet and the second gas inlet may be connected to a recirculation line for recirculating the gas leaving the irradiation unit via the second gas outlet back to the irradiation unit via the second gas inlet. The recirculation line may be equipped with an appropriate filter device, a heat exchanger, and a conveying device. The conveying device may be designed in the form of a pump or a compressor. The recirculation circuit must be sealed to avoid loss of the gas provided by the second gas source, for example, helium gas.

[0040] The second gas inlet may be configured to direct at least a portion of the gas flow introduced into the irradiation unit through the second gas inlet toward an absorber and / or reflector disposed within the irradiation unit to transfer heat from the absorber and / or reflector to the gas flow. Thus, the gas flow may be used to cool the absorber and / or reflector. The second gas source may be configured to provide cooling or heating gas. For this purpose, the second gas source may be in thermal contact with a second temperature control system configured to transfer heat to or remove heat from the gas introduced into the irradiation unit.

[0041] While the apparatus and the irradiation unit are operating to produce three-dimensional workpieces by irradiating a layer of raw material powder with electromagnetic or particle radiation, the second temperature control system is preferably operative to cool the gas introduced into the irradiation unit. Conversely, during a start-up phase of the apparatus before starting up the irradiation unit and before starting production of the three-dimensional workpieces, the second temperature control system may be operative to heat the gas introduced into the irradiation unit in order to heat the irradiation unit, and in particular the optical elements disposed therein, to a suitable operating temperature.

[0042] The first gas inlet of the processing chamber and the second gas inlet of the irradiation unit may be connected to separate gas sources and / or separate temperature control systems for the processing chamber and the irradiation unit, as described above. However, it is also conceivable to provide the apparatus with only one gas source and / or one temperature control system. The first gas inlet of the processing chamber and the second gas inlet of the irradiation unit may then be connected to the same gas source and / or the same temperature control system.

[0043] The absorber may comprise cooling fins. Preferably, the cooling fins of the absorber extend from the absorption surface and / or a surface of the absorber arranged opposite the absorption surface. The cooling fins are thus configured to transfer heat away from the absorber, in particular from the absorption surface. If the absorber comprises one or more absorption elements, at least one of the absorption elements may comprise cooling fins extending from the absorption surface and / or a surface of the absorption element arranged opposite the absorption surface.

[0044] Alternatively or additionally, the reflector may comprise cooling fins. Preferably, the cooling fins of the reflector extend from a surface of the reflector that is arranged opposite the reflecting surface. The cooling fins are thus configured to dissipate heat from the reflector, in particular from the reflecting surface. If the reflector comprises one or more reflecting elements, at least one of the reflecting elements may comprise cooling fins that extend from a surface of the reflecting element that is arranged opposite the reflecting surface.

[0045] The absorber may comprise at least one conditioning channel extending through the body of the absorber and / or extending adjacent to and in thermal contact with a surface of the absorber located opposite the absorbing side. If the absorber comprises one or more absorbing elements, at least one of the absorbing elements may comprise at least one conditioning channel extending through the body of the absorbing element and / or extending adjacent to and in thermal contact with a surface of the absorbing element located opposite the absorbing side.

[0046] Alternatively or additionally, the reflecting device may include at least one conditioning channel extending through the body of the reflecting device and / or extending adjacent to and in thermal contact with a surface of the reflecting device located opposite the reflecting surface. If the reflecting device includes one or more reflecting elements, at least one of the reflecting elements may include at least one conditioning channel extending through the body of the reflecting element and / or extending adjacent to and in thermal contact with a surface of the reflecting element located opposite the reflecting surface.

[0047] The conditioning channels of the absorber and / or reflector may be flowed with a suitable temperature control fluid. The temperature control fluid may be a liquid temperature control fluid or a gaseous temperature control fluid, such as air. The conditioning channels of the absorber and / or reflector may be in thermal contact with a third temperature control system configured to transfer heat to or reject heat from the temperature control fluid flowing through the conditioning channels.

[0048] While the apparatus and the irradiation unit are operating to produce three-dimensional workpieces by irradiating layers of raw material powder with electromagnetic or particle radiation, the third temperature control system preferably operates to cool the temperature control fluid flowing through at least one conditioning channel of the absorber and / or reflector. Conversely, during a start-up phase of the apparatus before starting up the irradiation unit and before starting production of three-dimensional workpieces, the third temperature control system may operate to heat the temperature control fluid flowing through the conditioning channel of the absorber and / or reflector in order to heat the processing chamber and / or irradiation unit and components of the apparatus in thermal contact with the processing chamber and / or irradiation unit to suitable operating temperatures.

[0049] The third temperature control system may be formed integrally with the first and / or second temperature control systems, but it is also conceivable to provide the apparatus with separate temperature control systems for the gases supplied to the treatment chamber and / or irradiation unit and for the temperature control fluid flowing through the conditioning channels of the absorber and / or reflector.

[0050] The apparatus may comprise at least one additional conditioning channel. The at least one additional conditioning channel may extend through a portion of the processing chamber wall and / or a portion of the irradiation unit housing wall that does not form at least part of the absorber and / or reflector. Alternatively or additionally, the at least one additional conditioning channel may extend adjacent to and in thermal contact with a portion of the processing chamber wall and / or a portion of the irradiation unit housing wall that does not form at least part of the absorber or reflector.

[0051] The additional conditioning channel may be flowed with a suitable temperature-control fluid. The temperature-control fluid may be a liquid temperature-control fluid or a gaseous temperature-control fluid, for example, air. Preferably, the additional conditioning channel is in thermal contact with a third temperature-control system. Thus, the temperature of the temperature-control fluid flowing through the additional conditioning channel may be controlled in the same way as the temperature-control fluid flowing through at least one conditioning channel of the absorber and / or reflector. However, it is also contemplated that the additional conditioning channel may be in thermal contact with a fourth temperature-control system that may control the temperature of the temperature-control fluid flowing through the additional conditioning channel independently of the temperature of the temperature-control fluid flowing through at least one conditioning channel of the absorber and / or reflector.

[0052] At least one of the first, second, third and fourth temperature control systems may be controlled in dependence on one or more temperature sensors measuring one or more of the temperature of the surface, the temperature of the gas stream and the temperature of the temperature control fluid. Additionally or alternatively, at least one of the temperature control systems may be controlled in dependence on build run data, in particular the percentage of the workpiece area of ​​the powder bed that is irradiated.

[0053] The absorber may be configured and arranged to thermally expand without imposing mechanical loads on the processing chamber and / or irradiation unit. Alternatively or additionally, the absorber may be configured and arranged to thermally expand without affecting the location of the irradiation unit relative to the carrier.

[0054] This may be achieved, for example, by designing the absorber in the form of a separate absorber element that is placed in the treatment chamber and / or irradiation unit in such a way that thermally induced deformations of the absorber element are not transmitted to the treatment chamber and / or irradiation unit. For example, the absorber element may be freely suspended within the treatment chamber and / or irradiation unit. Alternatively or additionally, the absorber may be connected to or integrated into the treatment chamber and / or irradiation unit via an expansion joint that prevents thermally induced deformations of the absorber element from being transmitted to the treatment chamber and / or irradiation unit.

[0055] A gap having a width of at least 0.1 mm may be provided between the irradiation unit housing wall facing the processing chamber or the support structure of the irradiation unit facing the processing chamber and the processing chamber wall facing the irradiation unit. For example, the irradiation unit may be provided with an appropriate support structure to position the irradiation unit, particularly the irradiation unit housing wall facing the processing chamber, at a desired distance from the processing chamber. As a result, the irradiation unit can be at least partially thermally isolated from the processing chamber to prevent excessive heat from being transferred from the processing chamber to the irradiation unit. A coolant, e.g., a cooling gas, may be flowed through the gap, and / or a thermal insulating material may be disposed within the gap.

[0056] The absorber may comprise at least one movable shielding element disposed within the processing chamber and associated with a functional tool housed therein. Alternatively or additionally, the reflector may comprise at least one movable shielding element disposed within the processing chamber and associated with a functional tool housed therein. For example, the movable shielding element of the absorber or reflector may be associated with a powder application device, a glove extending into the processing chamber for handling purposes, and / or a suction device for evacuating raw material powder from the processing chamber. The movable shielding element may be a simple plate-like element. However, it is also conceivable that the movable shielding element forms a kind of housing for accommodating the functional tool. The movable shielding element protects the functional tool from radiation emitted and / or reflected during selective irradiation of the raw material powder layer with electromagnetic or particle radiation. [Brief explanation of the drawings]

[0057] Preferred embodiments of the present invention will now be described in more detail with reference to the accompanying schematic drawings. [Figure 1] FIG. 1 shows an apparatus for producing three-dimensional workpieces by irradiating a layer of raw material powder with electromagnetic or particle radiation. DETAILED DESCRIPTION OF THE INVENTION

[0058] FIG. 1 illustrates an apparatus 10 for manufacturing three-dimensional workpieces by additive manufacturing. The apparatus includes a carrier 12 and a powder application device 14 for applying a raw material powder onto the carrier 12. The carrier 12 and the powder application device 14 are housed within a process chamber 16 that can be sealed from the ambient atmosphere. The internal atmosphere is established by a shielding gas supplied via a first gas inlet 18 in the process chamber 16. In the exemplary apparatus 10 illustrated in FIG. 1 , the first gas inlet 18 is formed by a porous process chamber wall portion 18a that forms part of the process chamber sidewall and an opening 18b formed in the process chamber sidewall. The gas supplied to the process chamber 16 via the first gas inlet 18 is provided by a first gas source 20 that includes a first gas storage container 22 and a first gas supply line 24. The first gas supply line 24 is connected to the first gas inlet 18.

[0059] The processing chamber 16 further includes a first gas outlet 25 for exhausting gas from the processing chamber 16. During operation of the apparatus 10, the gas stream introduced into the processing chamber 16 via the first gas inlet 18 and exhausted from the processing chamber 16 via the first gas outlet 25, as it is directed through the processing chamber 16 and across the carrier 12, attracts and entrains particulate impurities, such as soot, welding fumes, and powder particles, and exhausts such particulate impurities from the processing chamber 16. The first gas outlet 25 and the first gas inlet 18 are connected to a recirculation line (not shown). Via the recirculation line, gas exiting the processing chamber 16 via the first gas outlet 25 is recirculated back to the processing chamber 16 via the first gas inlet 18. A suitable filtration device (also not shown) may be disposed in the recirculation line to filter particulate impurities from the gas stream.

[0060] The apparatus 10 further comprises an irradiation unit 26 for selectively irradiating the raw material powder coated on the carrier 12 with electromagnetic or particle radiation. The irradiation unit 26 comprises at least one radiation beam source, in particular a laser beam source. In the exemplary apparatus 10 shown in Figure 1, the radiation source emits two radiation beams 30a, 30b that are processed in an appropriate manner by a pair of optical units 28. Each optical unit 28 comprises optical elements such as an objective lens and a scanner unit, which in turn comprises a diffractive optical element and / or at least one deflection mirror.

[0061] A transmission element 31, which transmits the radiation beams 30a, 30b emitted by the irradiation device 26 into the processing chamber 16, is arranged in an upper wall portion of the processing chamber 16. A gap 33 having a width of at least 0.1 mm is provided between a part of the irradiation unit housing wall 60 facing the processing chamber 16 and a part of the processing chamber wall 58 facing the irradiation unit 26. In particular, the irradiation unit 26 comprises a suitable support structure 35 for positioning the optical components of the irradiation unit 26, in particular the irradiation unit housing wall portion facing the processing chamber 16, at a desired distance from the processing chamber 16. As a result, the irradiation unit 26 is at least partially thermally isolated from the processing chamber 16.

[0062] The irradiation unit 26 includes a second gas inlet 32 ​​for introducing an inert gas into the irradiation unit 26. The inert gas is provided by a second gas source 34 including a second gas storage container 36 and a second gas supply line 38. The second gas supply line 38 is connected to the second gas inlet 32. The irradiation unit 26 further includes a second gas outlet 40 for exhausting gas from the irradiation unit 26.

[0063] The first and second gas sources 20, 34 are configured to provide cooling or heating gases. To this end, the first gas source 20 is in thermal contact with a first temperature control system 42 configured to transfer heat to or exhaust heat from gases introduced into the processing chamber 16. The second gas source 34 is in thermal contact with a second temperature control system 44 configured to transfer heat to or exhaust heat from gases introduced into the irradiation unit 26.

[0064] During operation of the apparatus 10 to manufacture the three-dimensional workpiece 46, a layer of raw material powder is applied onto the carrier 12 by the powder application device 14. To apply the layer of raw material powder, the powder application device 14 moves across the carrier 12. The layer of raw material powder is then selectively irradiated with electromagnetic or particle radiation according to the shape of a corresponding layer of the workpiece 18 being manufactured by the irradiation device 26.

[0065] The steps of applying layers of raw material powder onto the carrier 12 and selectively irradiating the layers of raw material powder with electromagnetic or particle radiation according to the shape of the corresponding layer of the workpiece 46 to be manufactured are repeated until the workpiece 46 reaches the desired shape and size. The carrier 12 is vertically movable within the built cylinder 48, so that the carrier 12 can move downward as the build height of the workpiece 48 increases as the workpiece 48 is built layer by layer from the raw material powder on the carrier 12. The carrier 12 can be equipped with a heater and / or a cooler.

[0066] While the apparatus 10 and irradiation unit 26 are operating to fabricate the three-dimensional workpiece 48 as described above, the first and second temperature control systems 42, 44 operate to cool the gases introduced into the process chamber 16 and irradiation unit 26. Conversely, during a start-up phase of the apparatus 10, prior to starting up the irradiation unit 26 and prior to beginning fabrication of the three-dimensional workpiece 48, the first and second temperature control systems 42, 44 operate to heat the gases introduced into the process chamber 16 and irradiation unit 26 in order to heat them to the appropriate operating temperature.

[0067] The apparatus 10 further comprises an absorption device 50 configured to absorb radiation emitted and / or reflected during the selective irradiation of the layer of raw material powder with electromagnetic or particle radiation. In Figure 1, the thermal radiation emitted during the selective irradiation of the layer of raw material powder with electromagnetic or particle radiation is schematically represented by a dotted pattern inside the process chambers 16, in the gaps 33 between the process chambers 16, and inside the irradiation unit 26.

[0068] The absorption device 50 comprises a plurality of absorption elements 52a-52e distributed within the process chamber 16 and the irradiation unit 26. The absorption device 50, i.e., each of the absorption elements 52a-52e, comprises an absorption surface 54 having a hemispherical reflectivity of less than 40%, preferably less than 20%, more preferably less than 10%, and most preferably less than 5%, for radiant energy with wavelengths in the range of 0.75 μm to 50 μm and / or for radiant energy with wavelengths in the range of 350 nm to 1100 nm, preferably 405-490 nm, 490-575 nm, and / or 805-1100 nm, respectively, of the electromagnetic or particle radiation used to selectively irradiate the layer of raw material powder.

[0069] Specifically, the absorbing surface 54 of each of the absorbing elements 52a-52e is anodized or coated with a black and / or opaque metallic or ceramic coating to provide an anodized absorbing surface layer or absorbing coating having a thickness of 0.1 μm to 1 mm. The surface roughness of the absorbing surface is in the range of 0.1 μm to 10 μm. The absorbing device 50, i.e., each of the absorbing elements 52a-52e, contains a material having a thermal conductivity of at least 10 W / (m*K), preferably at least 50 W / (m*K), and more preferably at least 100 W / (m*K).

[0070] Furthermore, the absorbing surface 54 of the absorbing device 50, ie, the absorbing surface 54 of each of the absorbing elements 52a-52e, faces the interior of the processing chamber 16 or the interior of the irradiation unit .

[0071] In particular, the absorber 50 has a plate-like body and includes two separate absorber elements 52d, 52e disposed within the irradiation unit 26. The two absorber elements 52d, 52e are provided with cooling fins 56 extending from surfaces of the absorber elements 52d, 52e, which are disposed on opposite sides of the absorbing surface 54. The absorber 50 further includes an absorber element 52a formed by a portion of the processing chamber wall 58 and two absorber elements 52b, 52c formed by a portion of the support structure 35 of the irradiation unit 26. Each of the absorber elements 52a, 52b, 52c includes a conditioning channel 62 extending through the body of the absorber element 52a, 52b, 52c. The absorber element 52a may be made of a translucent material. Alternatively, the absorber element 52a may be disposed in a recess formed in the processing chamber wall 58.

[0072] The apparatus 10 further comprises a reflecting device 64 configured to reflect heat and reflected laser radiation emitted during selective irradiation of the layer of raw material powder with electromagnetic or particle radiation. The reflecting device 64 comprises a plurality of reflecting elements 66a-66g distributed within the processing chamber 16 and the irradiation unit 26. Each of the reflecting devices 64, i.e., the reflecting elements 66a-66g, comprises a reflecting surface 68 having a hemispherical reflectivity of greater than 60%, preferably greater than 70%, more preferably greater than 80%, and most preferably greater than 90%, for radiant energy with a wavelength in the range of 0.75 μm to 50 μm and / or for radiant energy with a wavelength in the range of 350 nm to 1100 nm, preferably 405-490 nm, 490-575 nm, and / or 805-1100 nm, used to selectively irradiate the layer of raw material powder. Specifically, the reflective surface 68 of each of the reflective elements 66a-66g is coated with a white opaque coating or polished to provide a reflective coating having a thickness of 0.01 μm to 1 mm. The surface roughness of the reflective surface is less than 1 μm. The reflective device 64, i.e., each of the reflective elements 66a-66g, contains a material having a thermal conductivity of at least 10 W / (m*K), preferably at least 50 W / (m*K), and more preferably at least 100 W / (m*K).

[0073] Furthermore, the reflecting surface 68 of the reflecting device 64, that is, the reflecting surface 68 of each of the reflecting elements 66a to 66g, faces the interior of the processing chamber 16 or the interior of the irradiation unit .

[0074] In particular, reflecting device 64 comprises reflective elements 66a, 66b formed by portions of processing chamber wall 58 that have a reflective coating provided on their surfaces facing the interior of processing chamber 16. Reflecting element 66b is formed by an upper portion of processing chamber wall 58 that houses transmissive element 31. Additionally, reflecting device 64 comprises reflective element 66c formed by a portion of support structure 35 of irradiation unit 26 that has a reflective coating provided on its surface facing processing chamber 16. Reflecting elements 66a-66c have retroreflective properties and may therefore reflect heat and laser radiation from the powder bed back into the powder bed.

[0075] The reflecting device 64 further includes reflecting elements 66d, 66e formed by portions of the irradiating unit housing wall 60 with a reflective coating on the surface facing the interior of the irradiating unit 26. This reflects thermal radiation away from the deformation critical portion of the irradiating unit housing wall 60 and toward less affected areas within the irradiating unit 26. Each of the reflecting elements 66b, 66c includes an adjustment channel 70 extending through the body of the reflecting element 66b, 66c. The reflecting device 64 also includes two separate reflecting elements 66g, 66f with a plate-like body and disposed within the irradiating unit 26. The two reflecting elements 66g, 66f are provided with cooling fins 56 extending from surfaces of the reflecting elements 66g, 66f located on opposite sides of the reflective surface 68. The reflecting elements 66g, 66f may also include a concave reflective surface for dispersing reflected radiation.

[0076] Finally, the reflecting device 64 is disposed within the processing chamber 16 and includes a movable shielding element 72 associated with a functional tool housed within the processing chamber 16. In the exemplary apparatus 10 shown in Figure 1, the functional tool associated with the movable shielding element 72 is the powder application device 14. The movable shielding element 72 has a reflective coating applied to its exterior surface to form the reflective surface 68.

[0077] The apparatus 10 includes an additional conditioning channel 73 extending through a portion of the irradiation unit housing wall 60 that does not form at least part of the absorber 50 and / or reflector 64. A suitable temperature control fluid flows through the conditioning channels 62, 70 and additional conditioning channel 73 of the absorber 50 and reflector 64, and is in thermal contact with a schematically illustrated third temperature control system 74. The third temperature control system 74 is configured to transfer heat to the temperature control fluid flowing through the conditioning channels 62, 70 and additional conditioning channel 73, or to reject heat from the temperature control fluid flowing through the conditioning channels 62, 70 and additional conditioning channel 73.

[0078] While the apparatus 10 and the irradiation unit 26 are operating to produce the three-dimensional workpiece 46 by irradiating a layer of raw material powder with electromagnetic or particle radiation, the third temperature control system 74 operates to cool the temperature control fluid flowing through the conditioning channels 62, 70 and the additional conditioning channel 73 of the absorber 50 and the reflector 64. Conversely, during a start-up phase of the apparatus 10, before starting up the irradiation unit 26 and before starting production of the three-dimensional workpiece 48, the third temperature control system 74 operates to heat the temperature control fluid flowing through the conditioning channels 62, 70 and the additional conditioning channel 73 of the absorber 50 and the reflector 64 in order to heat the process chamber 16 and the irradiation unit 26 to an appropriate operating temperature.

[0079] To further control the temperature of the absorber 50 within the reflector 64, the first gas inlet 18 is configured to direct at least a portion of the gas flow introduced into the processing chamber 16 via the first gas inlet 18 toward the absorber 52, the reflector elements 66a, 66b, and the movable shielding element 72 to transfer heat from the absorber 52, the reflector elements 66a, 66b, and the movable shielding element 72 to the gas flow. Thus, the gas flow through the processing chamber 16 may be used to cool the absorber 50 and reflector 64 elements disposed within the processing chamber 16.

[0080] Similarly, the second gas inlet 37 is configured to direct at least a portion of the gas flow introduced into the irradiation unit 26 via the second gas inlet 37 towards the absorbing elements 52c, 52d and the reflecting elements 66d-66g, in order to transfer heat from the absorbing elements 52c, 52d and the reflecting elements 66d-66g to the gas flow. Thus, the gas flow may be used to cool the elements of the absorbing device 50 and the reflecting device 64 arranged in the irradiation unit 26. The following are some embodiments of the present invention. [Aspect 1] 1. An apparatus (10) for producing a three-dimensional workpiece (46) by irradiating a layer of raw material powder with electromagnetic or particle radiation, the apparatus (10) comprising: a treatment chamber (16) containing a carrier (12) and a powder application device (14) for applying a layer of raw material powder onto the carrier (12); an irradiation unit (26) for selectively irradiating the layers of raw material powder with electromagnetic or particle radiation according to the shape of the corresponding layer of the workpiece (18) to be produced, An apparatus (10) comprising an absorption device (50) configured to absorb radiation, provided within the processing chamber (16) and / or the irradiation unit (26) at a position such that the absorption device (50) can absorb radiation generated within the processing chamber (16) and / or the irradiation unit (26). [Aspect 2] the absorbing surface (54) of the absorber (50) faces the interior of the treatment chamber (16) and / or the interior of the irradiation unit (26), and / or the absorbing surface (54) of the absorbing device (50) has a hemispherical reflectivity of less than 40%, preferably less than 20%, even more preferably less than 10%, most preferably less than 5% for radiant energy with wavelengths in the range of 0.75 μm to 50 μm and / or for radiant energy with wavelengths in the range of 350 nm to 1100 nm, preferably 405 to 490 nm, 490 to 575 nm and / or 805 to 1100 nm, and / or The device (10) according to aspect 1, wherein the absorbing surface (54) of the absorbing device (50) is at least partially anodized, coated, foil-oxidized, structured and / or roughened, in particular laser black-marked. [Aspect 3] 3. The apparatus of claim 1, further comprising a reflector configured to reflect radiation within the processing chamber and / or the irradiation unit at a position capable of reflecting radiation generated within the processing chamber and / or the irradiation unit. [Aspect 4] the reflecting surface (68) of the reflector (64) faces the interior of the treatment chamber (16) and / or the interior of the irradiation unit (26), and / or the reflecting surface (68) of the reflecting device (64) has a hemispherical reflectivity of more than 60%, preferably more than 70%, even more preferably more than 80%, and most preferably more than 90% for radiant energy with a wavelength in the range of 0.75 μm to 50 μm and / or for radiant energy with a wavelength in the range of 350 nm to 1100 nm, preferably 405 to 490 nm, 490 to 575 nm and / or 805 to 1100 nm; and / or The device (10) according to aspect 3, wherein the reflective surface (68) of the reflector (64) is at least partially structured, foiled, coated and / or polished. [Aspect 5] 5. The apparatus (10) of any one of the preceding aspects, wherein at least one of the absorber (50) and the reflector (64) comprises a material having a thermal conductivity of at least 10 W / (m*K), preferably at least 50 W / (m*K), and more preferably at least 100 W / (m*K). [Aspect 6] the absorption device (50) comprises at least one separate absorption element (52c, 52d) arranged in the treatment chamber (16) and / or in the irradiation unit (26); and / or The apparatus (10) according to any one of aspects 1 to 5, wherein the reflecting device (64) comprises at least one separate reflecting element (66f, 66g) arranged in the processing chamber (16) and / or in the irradiation unit (26). [Aspect 7] the absorption device (50) comprises at least one absorption element (52a, 52b, 52c) formed by a part of the treatment chamber wall (58) and / or by a part of the irradiation unit housing wall (60); and / or The apparatus (10) according to any one of aspects 1 to 6, wherein the reflecting device (64) comprises at least one reflecting element (66a, 66b, 66c, 66d, 66e) formed by a portion of a processing chamber wall (58), a portion of a support structure (35) of the irradiation unit (26) and / or a portion of an irradiation unit housing wall (60). [Aspect 8] 8. The apparatus according to any one of claims 1 to 7, further comprising a transmission element (31) for transmitting the electromagnetic radiation or particle radiation emitted by the irradiation unit (26) into the processing chamber (16), the transmission element (31) being housed in a portion of the processing chamber wall (58) that forms the reflecting element (66b) of the reflecting device (64). [Aspect 9] The processing chamber (16) includes a first gas inlet (18) for introducing gas supplied by a first gas source (20) into the processing chamber (16); the first gas inlet (18) is configured to direct at least a portion of the gas flow introduced into the processing chamber (16) through the first gas inlet (18) to the absorber (50) and / or the reflector (64) disposed within the processing chamber (16) in order to transfer heat from the absorber (50) and / or the reflector (64) to the gas flow; and / or The apparatus (10) of any one of aspects 1 to 8, wherein the first gas source (20) is configured to provide a cooling gas or a heating gas. [Aspect 10] the irradiation unit (26) includes a second gas inlet (32) for introducing gas provided by a second gas source (34) into the irradiation unit (26); the second gas inlet (32) is configured to direct at least a portion of the gas flow introduced into the processing chamber (16) via the second gas inlet (32) to the absorber (50) and / or the reflector (64) arranged in the irradiation unit (26) in order to transfer heat from the absorber (50) and / or the reflector (64) to the gas flow; and / or The apparatus (10) of any one of aspects 1 to 9, wherein the second gas source (34) is configured to provide a cooling gas or a heating gas. [Aspect 11] the absorber (50) comprises, in particular, cooling fins (56) extending from the absorption surface (54) and / or from a surface of the absorber (50) located opposite the absorption surface (54); and / or The device (10) according to any one of the preceding aspects, wherein the reflector (64) comprises cooling fins (56) extending from a surface of the reflector (64) arranged opposite the reflecting surface (68). [Aspect 12] the absorber (50) comprises at least one conditioning channel (62) extending through the body of the absorber (50) and / or adjacent to and in thermal contact with a surface of the absorber (50) located opposite the absorption surface (54); and / or The device (10) of any one of aspects 1 to 11, wherein the reflector (64) comprises at least one conditioning channel (70) extending through the body of the reflector (64) and / or extending adjacent to and in thermal contact with the surface of the reflector (64) located opposite the reflective surface (68). [Aspect 13] the absorber (50) is constructed and arranged to thermally expand without exerting mechanical loads on the processing chamber (16) and / or the irradiation unit (26); and / or 13. The apparatus (10) of any one of aspects 1 to 12, wherein the absorption device (50) is constructed and arranged to thermally expand without affecting the location of the irradiation unit (26) relative to the carrier (12). [Aspect 14] 14. The apparatus (10) of any one of aspects 1 to 13, wherein a gap (33) having a width of at least 0.1 mm is provided between a portion of the irradiation unit housing wall (60) facing the processing chamber (16) or a support structure (35) of the irradiation unit (26) facing the processing chamber (16) and a portion of the processing chamber wall (58) facing the irradiation unit (26). [Aspect 15] the absorption device (50) is arranged in the processing chamber (16) and comprises at least one movable shielding element that is associated with a functional tool housed in the processing chamber (16); and / or The apparatus (10) according to any one of the preceding aspects, wherein the reflecting device (64) comprises at least one movable shielding element (72) arranged within the processing chamber (16) and adapted to engage a functional tool housed within the processing chamber (16).

Claims

[Claim 1] 1. An apparatus (10) for producing a three-dimensional workpiece (46) by irradiating a layer of raw material powder with electromagnetic or particle radiation, said apparatus (10) comprising: a treatment chamber (16) containing a carrier (12) and a powder application device (14) for applying a layer of raw material powder onto the carrier (12); an irradiation unit (26) for selectively irradiating the layers of the raw material powder with electromagnetic or particle radiation according to the shape of the corresponding layer of the workpiece (18) to be produced, The apparatus (10) includes an absorption device (50) configured to absorb radiation, the absorption device (50) being provided in the processing chamber (16) and / or the irradiation unit (26) at a position where it can absorb radiation generated inside the processing chamber (16) and / or inside the irradiation unit (26).

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