Apparatus and method for manufacturing three-dimensional workpieces

Abstract

The apparatus (10) is an apparatus (10) for manufacturing three-dimensional workpieces, and includes a process chamber (12), a carrier (14) configured to receive raw material powder, an irradiation device configured to selectively irradiate electromagnetic or particle radiation onto the carrier (14) to manufacture a workpiece made from the raw material powder by an additive manufacturing method, a transmission element (18) configured to enable transmission of the electromagnetic or particle radiation irradiated by the irradiation device (16) into the process chamber (12), and a gas supply element (19) for supplying the process chamber (12) with a gas. a gas supply device (26) configured to supply gas (D) from the processing chamber (12) and having at least one gas inlet (28, 32); a gas exhaust device (34) configured to exhaust gas from the processing chamber (12) and having at least one gas outlet (36); and a flow capture (44) configured to capture gas containing particulate impurities in a flow capture region (46) located downstream of the transmission element (18) with respect to the direction of gas flow (D) entering the processing chamber (12) through the at least one gas inlet (28, 32).

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. The present invention also relates to a method for producing three-dimensional workpieces. [Background technology]

[0002] Powder Bed Fusion (PBF) is an additive layering process 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 material powder is applied to a carrier and exposed to electromagnetic or particle radiation, depending on the desired geometry of the workpiece to be manufactured. The raw material powder is heated by the electromagnetic or particle radiation penetrating the powder layer, causing it to melt or sinter. Additional layers of raw material powder are then applied successively to the previously irradiated layer on the carrier until the workpiece has the desired shape and size. Particle Bed Fusion can be used, specifically based on CAD data, to manufacture prototypes, tools, replacement parts, or medical prosthetics.

[0003] The welding fume generated in particle bed fusion processes as the feedstock powder is irradiated and melted can contaminate the interior of the process chamber and also contaminate components of the irradiation system, such as lenses or windows through which the radiation beam directed into the process chamber passes. As a result, an increasing portion of the radiation energy irradiated by the irradiation system can be absorbed by the accumulated welding fume condensate.

[0004] EP 3321003 describes an apparatus for manufacturing three-dimensional workpieces by particle bed fusion, which suppresses absorption of radiation energy emitted by an irradiation system by welding condensed material from welding fume attached to the surface of a transmission element. The apparatus described in EP 3321003 includes a processing chamber containing a carrier for receiving raw material powder and an irradiation device for selectively irradiating the carrier with electromagnetic or particle radiation. The apparatus manufactures workpieces by an additive manufacturing method. The transmission element allows the electromagnetic or particle radiation emitted by the irradiation device to be transmitted into the processing chamber. The gas inlet includes a gas-permeable, panel-shaped porous member disposed in the region of a first sidewall of the processing chamber. A second sidewall of the processing chamber, located opposite the first sidewall, contains a gas outlet. The gas inlet and gas outlet are configured and arranged to generate a first gas flow of a protective gas. The first gas flow has a flow direction component flowing away from the transmission element. The additional gas inlet is disposed in a region below the gas-permeable porous member of the gas inlet in the first sidewall of the processing chamber. The additional gas inlet and the gas outlet are constructed and arranged to generate a second flow of protective gas. The second gas flow is directed substantially parallel to the carrier to ensure that particulate impurities generated in the processing chamber when electromagnetic radiation or particle radiation is irradiated onto the raw material powder on the carrier are removed from the processing chamber. Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention aims to provide an apparatus and method for producing three-dimensional workpieces by irradiating a layer of raw material powder with electromagnetic or particle radiation, and in particular, an apparatus and method capable of producing high-quality workpieces by maintaining stable operating conditions during operation. [Means for solving the problem]

[0006] This object is addressed by the device defined in claim 1 and the method defined in claim 14.

[0007] The apparatus for manufacturing three-dimensional workpieces includes a processing chamber. The apparatus further includes a carrier configured to receive raw material powder. The carrier may be housed within the processing chamber. However, it is also conceivable that the processing chamber can be moved across the carrier. The carrier may be a solid, fixed carrier having a surface onto which the raw material powder is applied to receive electromagnetic or particle radiation. However, the carrier is preferably designed to be vertically displaceable so that the carrier can be moved vertically downward as the workpiece is built up layer by layer from the raw material powder, increasing its build height. The raw material powder applied to the carrier in the processing chamber is preferably metal particles, particularly metal alloy particles, but may also be ceramic particles or particles containing other materials. The particles may have any suitable particle size or particle size distribution. However, it is preferred to process particles with a particle size of less than 100 μm.

[0008] The apparatus further comprises an irradiation device configured to selectively irradiate the raw material powder on the carrier with electromagnetic or particle radiation in order to manufacture a workpiece made from the particulate raw material powder by the additive manufacturing method. Using the irradiation device, the raw material powder applied to the carrier may be subjected to electromagnetic or particle radiation in a site-selective manner depending on the desired geometric shape of the workpiece to be manufactured. The irradiation device may comprise a radiation beam source, in particular a laser beam source, and may additionally comprise an optical unit for guiding and / or processing the radiation beam emitted from the radiation beam source. The optical unit may comprise an optical element such as an objective lens and a scanner unit, which preferably comprises a diffractive optical element and a deflection mirror.

[0009] Furthermore, the apparatus is provided with a transmission element configured to transmit the electromagnetic or particle radiation emitted by the irradiation device into the processing chamber. For example, the transmission element can be designed in the form of a window. Alternatively, the transmission element can comprise an optical element of the irradiation device, in particular a lens, or can consist of an optical element of the irradiation device.

[0010] The material of the transmission element can be selected depending on the type of radiation irradiated by the irradiation device to ensure the desired transmittance of the transmission element to the electromagnetic or particle radiation irradiated by the irradiation device. Furthermore, the material of the transmission element should be selected so that it can withstand the thermal load acting on the transmission element during operation of the apparatus for manufacturing the three-dimensional workpiece. For example, the transmission element may be made of a glass material or a suitable polymer material. If necessary, the transmission element may have a surface layer on the surface area facing the interior of the processing chamber to minimize adhesion and deposition of welding fume condensate on the surface of the transmission element.

[0011] The apparatus further includes a gas supply device. The gas supply device is configured to supply gas to the processing chamber and has at least one gas inlet. As described in EP 3321003, for example, the gas supply device preferably includes a first gas inlet defined by a gas-permeable porous panel disposed in the region of a first sidewall of the processing chamber, and a second gas inlet disposed in the region of the first sidewall of the processing chamber below the first gas inlet. The gas supplied by the gas supply device may be an inert gas, such as argon or nitrogen. The processing chamber may be sealable from the surrounding atmosphere so that a controlled atmosphere can be maintained inside. The controlled atmosphere may be an inert gas atmosphere to prevent undesired chemical reactions, particularly oxidation reactions.

[0012] The apparatus further includes a gas exhaust configured to exhaust gas from the processing chamber and having at least one gas exhaust port, which can be located in a second sidewall of the processing chamber opposite the first sidewall containing the one or more gas inlets.

[0013] The gas supply and gas discharge devices are preferably configured to generate a protective gas flow within the processing chamber. In particular, the first gas inlet and gas outlet of the gas supply device may be configured and arranged to have a flow direction component away from the transmission element to generate a first protective gas flow that protects the transmission element from contamination by impurities such as powder particles or welding fumes rising from the raw material powder coated on the carrier when the raw material powder on the carrier is irradiated with electromagnetic radiation or particle radiation. The second gas inlet and gas discharge port may be configured and arranged to be oriented substantially parallel to the carrier to generate a second protective gas flow that ensures removal of particulate impurities generated when the raw material powder on the carrier is irradiated with electromagnetic radiation or particle radiation from the processing chamber.

[0014] The flow cross-sectional area of ​​the at least one gas outlet of the gas discharge device may be smaller than the flow cross-sectional area of ​​the processing chamber such that the static pressure generated in the processing chamber is higher than the static pressure generated in the gas discharge device downstream of the at least one gas outlet. For example, the static pressure in the processing chamber may be about 20 mbar, and the static pressure in the gas discharge device downstream of the at least one gas outlet may be <20 mbar.

[0015] The recirculation line can connect the gas outlet to one or more gas inlets so that gases exiting the processing chamber through the gas outlet can be recirculated back into the processing chamber through one or more gas inlets. A suitable filter arrangement can be provided in the recirculation line to remove particulate impurities from the gases exiting the processing chamber before they are recirculated into the processing chamber. Furthermore, a suitable transport device, such as a pump or blower, can be provided in the recirculation line to supply gases into and exhaust gases from the processing chamber.

[0016] The apparatus further comprises a flow capture configured to capture gas containing particulate impurities within a flow capture region. The flow capture region is located downstream of the transmission element relative to the direction of gas flow entering the processing chamber through the at least one gas inlet. In the context of this application, the term "flow capture" defines any device or means configured to retain or "capture" gas containing particulate impurities within the flow capture region for a limited or unlimited retention time such that the particulate impurities accumulate within the flow capture region. This can be achieved, for example, by controlled manipulation and / or deceleration of the flow.

[0017] The flow capture area is preferably located within the processing chamber, i.e., defined by a region of the processing chamber. For example, the flow capture area may be bounded by a portion of the wall of the processing chamber. However, it is also contemplated that the flow capture area may be located outside the processing chamber and configured to direct or redirect gas containing particulate impurities toward a flow capture area located outside the processing chamber. The apparatus may have only one flow capture. However, it is also contemplated that the apparatus may include multiple flow captures, which may be located at different positions within or relative to the processing chamber.

[0018] When directed toward the flow capture region, the gas flow containing particulate impurities may be deflected or redirected from its primary original flow direction. However, when directed toward the flow capture region, the gas flow containing particulate impurities may maintain its primary original flow direction but still ultimately be captured, i.e., retained, within the flow capture region. The flow capture may be located within the processing chamber and may include one or more flow directing, flow deflecting, flow diverting, and / or flow retaining elements that may be defined by one or more components of the processing chamber, such as a processing chamber wall or a section of the processing chamber wall. However, the flow directing, flow deflecting, flow diverting, and / or flow retaining elements may include or be defined by gas jets or gas streams that affect the flow of the gas flow containing particulate impurities such that the gas flow containing particulate impurities is directed toward and / or trapped within the flow capture region.

[0019] The flow trap prevents particulate impurities contained in the gas stream downstream of the transmission element from reaching the transmission element and thereby contaminating it. In particular, the flow trap prevents particulate impurities from forming condensed particles that accumulate in the ascending flow component of the gas stream, such as from heating the gas when the feedstock powder is irradiated and evaporation of feedstock from a molten pool created by the impact of the radiation beam on the feedstock powder, so that the particulate impurities are retained downstream of the transmission element and are not drawn toward the transmission element.

[0020] Therefore, absorption of radiant energy by impurities adhering to the transmission element, such as smoke condensate deposited on the surface of the transmission element, can be minimized, and the apparatus for manufacturing three-dimensional workpieces can maintain stable operating conditions within the processing chamber for longer operating times. As a result, high-quality workpieces can be manufactured without interrupting the operation of the apparatus to clean the transmission element. Furthermore, damage to the transmission element due to impurity deposition can be prevented or at least significantly reduced.

[0021] Although the flow capture region is located downstream of the transmission element, a flow capture component, such as a flow directing element or a flow deflecting element, may be located upstream of the transmission element relative to the direction of gas flow entering the processing chamber through at least one gas inlet. It is also contemplated that the flow capture component may be located at least partially around the circumference of the transmission element. Additionally, the flow capture component may be located at any suitable location within the processing chamber.

[0022] The flow capture may include a shielding element. The shielding element may be positioned downstream of the transmission element with respect to the direction of gas flow entering the processing chamber through the at least one gas inlet and may be configured to shield the transmission element from gas containing particulate impurities trapped in the flow capture region. Specifically, the shielding element separates the flow capture region from the region of the processing chamber adjacent to the transmission element, thereby increasing the distance the gas and any particulate impurities contained therein must cover to reach the transmission element. Furthermore, the shielding element may act as a flow deflector flow diverter, for example, deflecting a flow component of a gas flow ascending within the processing chamber toward the top wall of the processing chamber so that the gas and any particulate impurities contained therein are trapped in the flow capture region.

[0023] The shielding element may extend from a wall of the processing chamber. Alternatively or additionally, the shielding element may have a first rim connected to the wall of the processing chamber and a second rim positioned opposite the first rim and facing the interior of the processing chamber. The flow capture may have a single shielding element. However, the flow capture may have multiple shielding elements that can surround the flow capture region, for example, on different sides of the flow capture region.

[0024] The shielding element may be positioned at an angle relative to the direction of gas flow entering the processing chamber through the at least one gas inlet such that a second rim of the shielding element is positioned downstream of a first rim of the shielding element relative to the direction of gas flow entering the processing chamber through the at least one gas inlet. The angled shielding element is particularly well suited to retaining gas and particulate impurities within a flow capture region downstream of the transmission element.

[0025] The shielding element may comprise a substantially plate-shaped element. Alternatively or additionally, the shielding element may be made of metal, polymer and / or inorganic material. The material of the shielding element is preferably selected to ensure that the shielding element can withstand the temperatures in the processing chamber when irradiating the raw material powder. The shielding device may be provided with a surface capable of absorbing and / or reflecting radiation. For example, the surface of the shielding element may be anodized, foil coated, oxidized and / or roughened, in particular laser black mark treated.

[0026] The shielding element may also comprise a shielding gas jet. For example, the shielding gas jet may form a type of gas curtain extending from a top wall and / or at least one side wall of the processing chamber and defined by injecting gas into the interior of the processing chamber through suitable shielding gas jet inlets formed in the top wall and / or at least one side wall of the processing chamber. The shielding element may also be formed by a region of the processing chamber wall that is offset from a peripheral region of the processing chamber wall, thereby forming an edge or recess in the processing chamber wall.

[0027] The transmission element may be arranged in a region of the wall of the processing chamber, in particular in a region of the upper wall of the processing chamber. For example, the transmission element may be integrated into the wall of the processing chamber, in particular in the upper wall of the processing chamber. In a particularly preferred embodiment of the device, the transmission element is arranged in a region above the carrier, in particular in a central region of the carrier.

[0028] The flow capture may be configured to capture gas containing particulate impurities within a flow capture region disposed adjacent to the top wall of the processing chamber. Positioning the flow capture region adjacent to the top wall of the processing chamber is particularly advantageous when the transmission element is disposed in the region of the top wall of the processing chamber. The flow capture region may then be bounded by a portion of the top wall of the processing chamber disposed downstream of the transmission element relative to the direction of gas flow entering the processing chamber through at least one gas inlet. Alternatively or additionally, the flow capture region may be bounded by a portion of the second side wall, particularly a portion of the second side wall disposed above the gas outlet.

[0029] In particular, if the transmission element is arranged in the region of the top wall of the processing chamber, the shielding element may extend from the top wall of the processing chamber and / or a first rim of the shielding element may be connected to the top wall of the processing chamber. A second rim of the shielding element may face the carrier for receiving the raw material powder. However, it is also conceivable that the first rim of the shielding element is connected to a side wall of the processing chamber. For example, the first rim of the shielding element may be connected to the second side wall of the processing chamber above the gas outlet, and the second rim of the shielding element may face the first side wall of the processing chamber.

[0030] The flow rate of the gas entering the processing chamber through the at least one gas inlet may be greater than the flow rate of the gas containing the particulate impurities as it flows through the at least one gas inlet. Reducing the flow rate of the gas containing the particulate impurities is useful for retaining the gas, particularly the particulate impurities, within the flow capture region.

[0031] Furthermore, the apparatus preferably includes a flow deflection element configured to deflect the flow of gas containing particulate impurities toward the flow capture region and / or toward at least one gas outlet of the gas discharge device. The flow deflection element may form a component of the flow capture, but may alternatively be designed independently of the flow capture. The flow deflection element is preferably positioned downstream of the transmission element with respect to the direction of gas flow entering the processing chamber through the at least one gas inlet.

[0032] The flow deflection element may be disposed adjacent to a sidewall of the processing chamber or may be integrally formed with the sidewall of the processing chamber. For example, the flow deflection element may be disposed adjacent to a member integrally formed with a second sidewall of the processing chamber. The flow deflection element may also be disposed above at least one gas outlet of the gas discharge device.

[0033] The flow deflection element may have a rounded and / or bulged structure. For example, the flow deflection element may be defined by a curved sheet of material, or may include a bulged portion of a wall of the processing chamber, particularly a bulged portion of a second sidewall of the processing chamber. The flow deflection element may have a first section configured to direct a flow of gas containing particulate impurities toward the flow capture region. The first section may have a first rim connected to the sidewall of the processing chamber. The first section may further have a second rim positioned opposite the first rim and facing the interior of the processing chamber. The first section may be angled with respect to the direction of gas flow entering the processing chamber through the at least one gas inlet such that the first rim is positioned downstream of the second rim.

[0034] The flow deflecting element may further include a second section configured to direct the flow of gas containing particulate impurities toward at least one gas outlet of the gas discharge device. The second section may include a first rim connected to a sidewall of the processing chamber. The second section may further include a second rim positioned opposite the first rim and facing the interior of the processing chamber. The second section may be angled with respect to the direction of gas flow entering the processing chamber through the at least one gas inlet such that the first rim is positioned downstream of the second rim.

[0035] The flow deflecting element may also have a third section extending substantially perpendicular to the direction of gas flow entering the processing chamber through the at least one gas inlet. For example, the third section of the flow deflecting element may extend substantially parallel to a sidewall of the processing chamber, particularly a second sidewall of the processing chamber to which the first and second sections are connected. Alternatively or additionally, the third section may extend between a second rim of the first section and a second rim of the second section.

[0036] The first, second, and / or third sections of the flow deflection element may be disposed adjacent to or integrally formed with the sidewall of the processing chamber. The flow deflection element may be designed to have separate first, second, and third sections. However, the first, second, and third sections of the flow deflection element may be integrally formed with each other, thereby integrating with each other. For example, the flow deflection element may not have a distinct rim that clearly delimits the sections of the flow deflection element.

[0037] The apparatus may further include a cooling element configured to cool the particulate impurity-laden gas trapped in the flow capture region. The cooling element may be disposed adjacent to or integrally formed with a portion of the processing chamber wall that bounds the flow capture region. Cooling the particulate impurity-laden gas promotes deposition of the particulate impurities, for example, on the cooling element. As a result, the presence of the cooling element enhances protection of the transmission element from contamination by particulate impurities.

[0038] The cooling element may be an active cooling element or a passive cooling element. The cooling element may have cooling channels through which a coolant, such as water, can flow. Alternatively or additionally, the cooling element may have or be made of a material with a higher thermal conductivity than the surrounding material. The cooling element may also be provided with cooling fins and / or have a large surface area to enable rapid cooling of the trapped gas. The cooled gas typically flows downward toward the gas outlet, away from the transmission element. Furthermore, the downward flow of the cooled gas provides room for "new" smoke / gas clouds to flow and be captured in the capture area.

[0039] In a preferred embodiment, the apparatus includes a removal device configured to remove gas containing particulate impurities from the flow capture region. Furthermore, removing particulate impurities from the flow capture region enhances protection of the transmission element from contamination by particulate impurities. The removal device can be employed in an apparatus with a flow capture having the above-described shielding and / or flow deflecting elements. However, it is also contemplated that the removal device can be employed in an apparatus in which flow capture is achieved without a shielding and / or flow deflecting element. Such flow capture may be defined by or include any device or means configured to retain or "trap" gas containing particulate impurities within the flow capture region for a limited or unlimited retention time, e.g., by controlled manipulation and / or deceleration of the flow, such that the particulate impurities accumulate within the flow capture region.

[0040] The removal device may include a connecting device. A first end of the connecting device may be connected to the flow capture area. The removal device may further include a conveying device, such as a pump, configured to convey the gas containing particulate impurities from the flow capture area. The conveying device may be disposed in the connecting device. The connecting device may include one or more hoses. Optionally, a valve may be disposed in the connecting device to enable or disable removal of the gas containing particulate impurities from the flow capture area.

[0041] The second end of the connecting device may be open, for example, connected to a collection vessel configured to receive gas and, in particular, particulate impurities removed from the flow capture region. However, the second end of the connecting device may also be connected to a gas evacuation device. For example, the connecting device may connect the flow capture region to a pipe that opens into the gas evacuation device downstream of the gas outlet. Optionally, a valve disposed on the connecting device may be configured to allow or stop the removal of gas containing particulate impurities from the flow capture region into the gas evacuation device.

[0042] As described above, the cross-sectional flow area of ​​the gas outlet may be smaller than the cross-sectional flow area of ​​the processing chamber so that the static pressure generated in the processing chamber is higher than the static pressure generated in the gas discharge device downstream of the gas outlet. Thus, the discharge of gas through the gas outlet may be induced or promoted by the Venturi effect. Furthermore, the cross-sectional flow area of ​​the connecting device may be smaller than the cross-sectional flow area of ​​the gas discharge device downstream of at least one gas outlet so that the discharge of gas containing particulate impurities from the flow capture region to the gas discharge device may be induced or promoted by the Venturi effect.

[0043] In a method for manufacturing a three-dimensional workpiece, a layer of raw material powder is applied to a carrier housed in a processing chamber. To manufacture a workpiece made from the raw material powder by an additive manufacturing method, the raw material powder on the carrier is selectively irradiated with electromagnetic radiation or particle radiation. The electromagnetic radiation or particle radiation is transmitted into the processing chamber via a transmission element. Gas is supplied to the processing chamber via at least one gas inlet of a gas supply device. The gas is exhausted from the processing chamber via at least one gas outlet of a gas exhaust device. By flow capture, gas containing particulate impurities is captured in a flow capture region located downstream of the transmission element with respect to the direction of gas flow entering the processing chamber via the at least one gas inlet.

[0044] The flow trap may include a shielding element disposed downstream of the transmission element relative to the direction of flow of gas entering the processing chamber through the at least one gas inlet, and configured to shield the transmission element from the gas containing particulate impurities trapped in the flow trapping region. The flow trap may capture the gas containing particulate impurities in a flow trapping region disposed adjacent to an upper wall of the processing chamber. The flow velocity of the gas entering the processing chamber through the at least one gas inlet as it flows through the at least one gas inlet may be greater than the flow velocity of the gas containing particulate impurities as it is trapped in the flow trapping region.

[0045] The flow capture may include a flow deflecting element for deflecting the flow of gas containing particulate impurities toward the flow capture region and / or toward at least one gas outlet of the gas discharge device. The flow deflecting element may be located adjacent to a sidewall of the processing chamber or may be integrally formed with the sidewall of the processing chamber, and in particular may be located above or integrally formed with the at least one gas outlet of the gas discharge device.

[0046] The flow deflecting element may have a first section configured to direct the flow of gas containing particulate impurities toward the flow capture region. The first section may have a first rim connected to a sidewall of the processing chamber and a second rim disposed opposite the first rim and facing the interior of the processing chamber. The first section may be angled with respect to the direction of gas flow entering the processing chamber through the at least one gas inlet such that the first rim is disposed downstream of the second rim with respect to the direction of gas flow entering the processing chamber through the at least one gas inlet.

[0047] The flow deflecting element may further include a second section configured to direct the flow of gas containing particulate impurities toward at least one gas outlet of the gas discharge device. The second section may include a first rim connected to a sidewall of the processing chamber and a second rim disposed opposite the first rim and facing the interior of the processing chamber. The second section may be inclined with respect to the direction of gas flow entering the processing chamber through the at least one gas inlet such that the first rim is disposed downstream of the second rim with respect to the direction of gas flow entering the processing chamber through the at least one gas inlet.

[0048] The flow deflection element may also have a third section extending substantially perpendicular to the direction of gas flow entering the processing chamber through the at least one gas inlet and / or extending between the second rim of the first section and the second rim of the second section.

[0049] In the method for manufacturing a three-dimensional workpiece, gas containing particulate impurities may be removed from the flow capture region. The removal device may include a connecting device. A first end of the connecting device may be connected to the flow capture region. The gas containing particulate impurities may be removed from the flow capture region by a conveying device, such as a pump. A second end of the connecting device may be open and may be connected to, for example, a collection vessel configured to receive the gas and in particular the particulate impurities removed from the flow capture region. However, the second end of the connecting device may be connected to a gas discharge device. Further features described above with respect to the apparatus for manufacturing a three-dimensional workpiece may also be present in the method for manufacturing a three-dimensional workpiece.

[0050] Preferred embodiments of the invention will now be described in more detail with reference to the accompanying schematic drawings, in which: FIG. [Brief explanation of the drawings]

[0051] [Figure 1] 1 illustrates a first embodiment of an apparatus for manufacturing a three-dimensional workpiece. [Figure 2] FIG. 2 illustrates a second embodiment of an apparatus for manufacturing a three-dimensional workpiece. DETAILED DESCRIPTION OF THE INVENTION

[0052] 1 shows a first embodiment of an apparatus 10 for manufacturing three-dimensional workpieces by an additive manufacturing process. The apparatus 10 has a process chamber 12 that houses a carrier 14 for receiving raw material powder. A powder application device 15 serves to apply the raw material powder onto the carrier 14. The carrier 14 is designed to be vertically displaceable so that the carrier 14 can move vertically downward as the build height of the workpiece increases as it is formed layer by layer from the raw material powder on the carrier 14.

[0053] Furthermore, the apparatus 10 for manufacturing three-dimensional workpieces comprises an irradiation device 16 for selectively irradiating raw material powder applied on the carrier 14 with electromagnetic or particle radiation, in particular laser radiation, in order to manufacture workpieces made from the raw material powder by an additive manufacturing method. By means of the irradiation device 16, the raw material powder on the carrier 14 may be subjected to electromagnetic or particle radiation in a location-selective manner depending on the desired geometric shape of the component to be manufactured. The irradiation device 16 comprises a radiation source which may comprise a diode-pumped ytterbium fiber laser emitting laser light at a wavelength of approximately 1070-1080 nm.

[0054] The irradiation device 16 further comprises an optical unit for guiding and processing the radiation beam emitted by the radiation source. The optical unit may comprise a beam expander for expanding the radiation beam, a scanner and an objective lens. Alternatively, the optical unit may comprise a beam expander including focusing optics and a scanner unit. The scanner unit allows changing and adjusting the position of the focus of the radiation beam both in the direction of the beam path and in a plane perpendicular to the beam path. The scanner unit may be designed in the manner of a galvanometer scanner and the objective lens may be an f-theta objective lens.

[0055] The apparatus 10 further includes a transmission element 18 that transmits the electromagnetic or particle radiation emitted by the irradiation device 16 into the processing chamber 12. In the illustrated apparatus 10, the transmission element 18 includes two windows 20 and 22 made from glass or a polymer material and positioned in a region of the top wall 24 of the processing chamber 12 above the center of the carrier 14. Thus, the radiation beam emitted by the irradiation device 16 can be directed across the carrier 14 through the windows 20 and 22 of the transmission element 18 as desired, depending on the geometry of the workpiece being manufactured.

[0056] The processing chamber 12 is sealed from the ambient atmosphere, i.e., the environment surrounding the processing chamber 12. A gas supply device 26 serves to supply gas to the processing chamber 12, having a first gas inlet 28 and a second gas inlet 32. The first gas inlet 28 is defined by a panel-shaped gas-permeable porous member disposed in the region of a first sidewall 30 of the processing chamber 12, and the second gas inlet 32 ​​is disposed in the first sidewall 30 of the processing chamber 12 in the region below the first gas inlet 28. The gas supplied by the gas supply device 26 may be an inert gas, such as argon or nitrogen. The gas is transported into the processing chamber 12 by an appropriate transport device, such as a pump or a blower (not shown).

[0057] The apparatus 10 further includes a gas exhaust device 34. The gas exhaust device 34 serves to exhaust gases, particularly gases containing particulate impurities generated within the processing chamber 12 when irradiated onto the raw material powder on the carrier 14, from the processing chamber 12, and includes a gas exhaust port 36 disposed in a second sidewall 38 of the processing chamber 12. The second sidewall 38 of the processing chamber 12 is disposed opposite the first sidewall 30.

[0058] The gas outlet 36 is connected to a gas exhaust line 40, which is connected to the gas supply system 26 via a recirculation line (not shown), allowing gases exiting the processing chamber 12 via the gas outlet 36 to be recirculated back into the processing chamber 12 via the first gas inlet 28 and the second gas inlet 32. A suitable filter arrangement (not shown) is provided in the recirculation line to remove particulate impurities from the gases exiting the processing chamber 12 via the gas outlet 36 before the gases are recirculated into the processing chamber 12. The discharge of gases from the processing chamber 12 via the gas outlet 36 and the gas exhaust line 40 is controlled by a valve 42 disposed in the gas exhaust line 40.

[0059] The gas supply device 26 and the gas exhaust device 34 are configured to generate protective gas flows F1 and F2 within the processing chamber 12, with the first gas flow F1 flowing from the first gas inlet 28 to the gas exhaust port 36 and the second gas flow F2 flowing from the second gas inlet 32 ​​to the gas exhaust port 36. The supply of gases to the processing chamber 12 is controlled so that the volumetric flow rate of gas into the processing chamber 12 via the first gas inlet 28, i.e., the volumetric flow rate of the first gas flow F1, is greater than the volumetric flow rate of gas into the processing chamber 12 via the second gas inlet 32, i.e., the volumetric flow rate of the second gas flow F2. However, the flow rate of the first gas flow F1 is slower than the flow rate of the second gas flow F2.

[0060] At least in the region of the processing chamber 12 adjacent to the second gas inlet 32, the second gas flow F2 is directed substantially parallel to the carrier 14, ensuring that particulate impurities generated within the processing chamber 12 when the raw material powder on the carrier 14 is irradiated with electromagnetic or particle radiation are removed from the processing chamber 12. Conversely, the first gas flow F1 has a flow direction component v1 away from the transmission element 18. That is, the gas supplied to the processing chamber 12 via the first gas inlet 28 increases the distance from the top wall 24 of the processing chamber 12 that houses the transmission element 18 as it flows through the processing chamber 12 after passing through the transmission element 18. Therefore, the first gas flow F1 protects the transmission element 18 from being contaminated by impurities, such as powder particles or welding fumes, that rise from the raw material powder applied to the carrier 14 when irradiated with electromagnetic or particle radiation.

[0061] Because the cross-sectional flow area of ​​the gas outlet 36 is smaller than the cross-sectional flow area of ​​the processing chamber 12, the static pressure generated within the processing chamber 12 is higher than the static pressure generated within the gas exhaust device 34 downstream of the gas outlet 36, such as the gas exhaust line 40. The static pressure within the processing chamber 12 may be, for example, about 20 mbar, and the static pressure within the gas exhaust line 40 may be <20 mbar.

[0062] Irradiation of the raw material powder on the carrier 14 introduces heat into the processing chamber 12. As a result, the temperature of the second gas flow F2, in particular, increases with increasing distance from the first gas inlet 28 and the second gas inlet 32. Thus, in the region of the processing chamber 12 adjacent the gas outlet 36, the second gas flow F2 has a flow direction component v2 directed away from the carrier 14 toward the top wall 24 of the processing chamber 12. The upward gas flow component f typically carries particulate impurities, such as raw material powder particles and / or condensed particles formed by evaporation of raw material from a molten pool created by the impact of the radiation beam on the raw material powder.

[0063] Thus, the apparatus 10 includes a flow capture 44 configured to capture gas containing particulate impurities in a flow capture region 46. The flow capture region 46 is disposed within the processing chamber 12 downstream of the transmission element 18 with respect to the flow direction D of gas entering the processing chamber 12 via the first gas inlet 28 and the second gas inlet 32. The flow capture 44 captures the gas containing particulate impurities, specifically the impurity-laden gas flow component f rising toward the top wall 24 in the region of the gas outlet 36, within the flow capture region 46 for a limited or unlimited retention time, such that the particulate impurities accumulate within the flow capture region 46. Thus, the flow capture 44 prevents the particulate impurities from reaching the transmission element 18 and contaminating it.

[0064] The second gas flow F2 entering the processing chamber 12 via the second gas inlet 32 ​​has a faster flow rate through the second gas inlet 32 ​​than the flow rate of the gas containing the particulate impurities as it is captured in the flow capture region 46. Slowing the flow rate of the gas containing the particulate impurities helps to retain the impurity-laden gas within the flow capture region 46.

[0065] 1, the flow capture area 46 is located in the region of the top wall 24 of the processing chamber 12 and is bounded by the top wall 24 and a portion of the second side wall 38 connected to the top wall 24. The portion of the second side wall 38 connected to the top wall 24 and bounding the flow capture area 46 is inclined toward the first side wall 30 relative to the carrier 14. However, it is also contemplated that the flow capture area 46 may be bounded by a portion of the second side wall 38 that extends substantially perpendicular to the carrier 14 and / or parallel to the first side wall 30.

[0066] The flow capture 44 includes a shielding element 48 positioned downstream of the transmission element 18 relative to the direction of gas flow D entering the processing chamber 12 via the first gas inlet 28 and the second gas inlet 32, thereby shielding the transmission element 18 from gas containing particulate impurities trapped within the flow capture region 46. Specifically, the shielding element 48 separates the flow capture region 46 from the region of the processing chamber 12 adjacent to the transmission element 18, thereby increasing the distance that the gas and particulate impurities contained in the flow capture region 46 must cover to reach the transmission element 18. Additionally, the shielding element 48 acts as a flow deflecting element that deflects the upward flow component f of the second gas flow F2 so that the gas and particulate impurities contained in the gas are directed into the flow capture region 46 and ultimately captured.

[0067] The shielding element 48 has a first rim connected to a wall of the processing chamber 12, specifically the top wall 24, and a second rim disposed opposite the first rim and facing the interior of the processing chamber 12. Thus, the shielding element 48 protrudes from the wall of the processing chamber 12, specifically the top wall 24, into the interior of the processing chamber 12. The shielding element 48 is also inclined with respect to the flow direction D of the gas flowing into the processing chamber 12 via the first gas inlet 28 and the second gas inlet 32 ​​such that the second rim of the shielding element 48 is disposed downstream of the first rim of the shielding element 48.

[0068] 1, the shielding element 48 comprises a generally plate-shaped element made of metal. However, the shielding element 48 may also be defined by or include a shielding gas jet that forms a gas curtain extending from a wall, specifically the top wall 24 of the processing chamber 12, into the interior of the processing chamber 12. The shielding gas jet may be defined by injecting gas into the processing chamber 12 through a suitable shielding gas jet inlet formed in the wall, specifically the top wall 24 of the processing chamber 12.

[0069] The apparatus 10 further includes a flow deflection element 50 configured to deflect a gas flow containing particulate impurities, specifically, an impurity-laden gas flow component f rising toward the upper wall 24 in the region of the gas outlet 36, toward the flow capture area 46 and / or toward the gas outlet 36 of the gas evacuation device 34. The flow deflection element 50 is positioned downstream of the transmission element 18 with respect to the flow direction D of gas entering the processing chamber 12 via the first gas inlet 28 and the second gas inlet 32. In the apparatus 10 shown in FIG. 1 , the flow deflection element 50 is positioned adjacent to a sidewall, specifically, the second sidewall 38 of the processing chamber 12 above the gas outlet 36. However, it is also contemplated that the flow deflection element 50 may be formed integrally with the second sidewall 38.

[0070] The flow deflecting element 50 has a first section 52 configured to direct a gas flow, configured to direct a gas flow component f carrying particulate impurities, specifically impurities rising toward the top wall 24 in the region of the gas outlet 36, toward the flow capture region 46. The first section 52 has a first rim connected to the second sidewall 38 of the processing chamber 12 and a second rim positioned opposite the first rim and facing the interior of the processing chamber 12. The first section 52 is inclined with respect to the flow direction D of gas entering the processing chamber 12 through the first gas inlet 28 and the second gas inlet 32 ​​such that the first rim is positioned downstream of the second rim.

[0071] Furthermore, the flow deflecting element 50 has a second section 54 configured to direct the flow of gas containing particulate impurities, specifically, in the region of the gas outlet 36, a second gas flow component f′ still flowing substantially parallel to the carrier 14, toward the gas outlet 36 of the gas discharge device 34. The second section 54 has a first rim connected to the second sidewall 38 of the processing chamber 12 and a second rim positioned opposite the first rim and facing the interior of the processing chamber 12. The second section 54 is inclined with respect to the flow direction D of gas entering the processing chamber 12 through the first gas inlet 28 and the second gas inlet 32 ​​such that the first rim is positioned downstream of the second rim.

[0072] The flow deflection element 50 also has a third region 56 that extends substantially perpendicular to the flow direction D of gas entering the processing chamber 12 through the first gas inlet 28 and the second gas inlet 32 ​​and that is substantially parallel to the second sidewall 38 of the processing chamber 12. The third region 56 further extends between the second rim of the first region 52 and the second rim of the second region 54.

[0073] The flow deflection element 50 may be replaced by a second flow capture area. Additionally, the flow deflection element 50 may have a rounded and / or bulged structure. For example, the flow deflection element 50 may be defined by, include, or be defined by a curved sheet of material or a bulged portion of the second sidewall 38 of the processing chamber 12.

[0074] The apparatus 10 also includes a cooling element 58 configured to cool the gas containing particulate impurities trapped in the flow capture region 46. In the apparatus 10 of Figure 1, the cooling element 58 is integrated into a portion of the top wall 24 of the processing chamber 12 that bounds the flow capture region 46.

[0075] 2 illustrates a second embodiment of the apparatus 10 for manufacturing three-dimensional workpieces by additive layering. The apparatus 10 illustrated in FIG. 2 differs from the arrangement of FIG. 1 in that it includes a removal device 60 that functions to remove gas containing particulate impurities from the flow capture region 46. The removal device 60 includes a connection device 62. A first end of the connection device 62 is connected to the flow capture region 46. The removal device 60 may also include a transport device (not shown), such as a pump, configured to transport the gas containing particulate impurities from the flow capture region 46. The transport device may be disposed within the connection device 62.

[0076] The second end of the connecting device 62 may be open and may be connected, for example, to a collection container (not shown) configured to receive gas, particularly particulate impurities, removed from the flow capture area 46. However, in the arrangement of FIG. 2 , the second end of the connecting device 62 is connected to the gas discharge device 34. Specifically, the connecting device 62 has one or more hoses 64 connected to a pipe 66 that opens the flow capture area 46 into the gas discharge device 34 downstream of the gas outlet 36. However, the connecting device 62 may have other means for connecting the flow capture area 46 to the gas discharge device 34, such as a bypass channel routed along the second side wall 38. Specifically, the pipe 66 opens into the gas discharge line 40 downstream of the gas outlet 36.

[0077] A valve 68 is disposed in the connecting device 62, specifically the pipe 66, to enable or stop the removal of gas containing particulate impurities from the flow capture area 46 into the gas outlet 36 as needed. Because the cross-sectional flow area of ​​the connecting device 62 is smaller than the cross-sectional area of ​​the gas outlet 36 downstream of the gas outlet 36, i.e., the cross-sectional flow area of ​​the gas outlet line 40, the discharge of gas containing particulate impurities from the flow capture area 46 into the gas outlet 36 may be induced or at least facilitated by the Venturi effect. The length of the pipe 66 may be selected to increase the pressure difference between the connecting device 62 and the gas outlet 36 downstream of the gas outlet 36 and to compensate for the potential drop at the end of the pipe 66.

[0078] Otherwise, the structure and function of the device 10 shown in FIG. 2 corresponds to the structure and function of the device 10 according to FIG.

[0079] 2, the removal device 60 is employed in an apparatus 10 having a flow capture 44 including a shielding element 48 and a flow deflection element 50. However, it is also contemplated that the removal device 60 may be employed in an apparatus 10 in which the flow capture 44 is implemented without the shielding element 48 and / or the flow deflection element 50, and implemented using another suitable means configured to retain or "trap" gas containing particulate impurities within the flow capture region 46, for example, by controlled manipulation and / or deceleration of the flow.

Claims

1. An apparatus (10) for manufacturing a three-dimensional workpiece, comprising: a processing chamber (12); a carrier (14) configured to receive the raw material powder; an irradiation device configured to selectively irradiate the raw material powder on the carrier (14) with electromagnetic or particle radiation in order to produce a workpiece made from the raw material powder by an additive manufacturing method; a transmission element (18) configured to allow transmission of the electromagnetic or particle radiation emitted by the irradiation device (16) into the processing chamber (12); a gas supply (26) configured to supply gas to the processing chamber (12) and having at least one gas inlet (28, 32); a gas exhaust device (34) configured to exhaust gases from the processing chamber (12) and having at least one gas exhaust port (36); a flow capture (44) configured to capture gas containing particulate impurities in a flow capture region (46) located downstream of the transmission element (18) relative to a direction of gas flow (D) entering the processing chamber (12) through the at least one gas inlet (28, 32); An apparatus (10) comprising:

2. 2. The apparatus (10) of claim 1, wherein the flow capture (44) comprises a shielding element (48) positioned downstream of the transmission element (18) with respect to the direction of gas flow (D) entering the processing chamber (12) through the at least one gas inlet (28, 32) and configured to shield the transmission element (18) from gas containing particulate impurities trapped in the flow capture region (46).

3. 3. The apparatus (10) of claim 2, wherein the shielding element (48) has a first rim extending from and / or connected to a wall of the processing chamber (12), and a second rim positioned opposite the first rim and facing the interior of the processing chamber (12).

4. 4. The apparatus (10) of claim 3, wherein the shielding element (48) is positioned at an angle with respect to a direction of gas flow (D) entering the processing chamber (12) through the at least one gas inlet (28, 32) such that the second rim of the shielding element (48) is positioned downstream of the first rim of the shielding element (48) with respect to a direction of gas flow (D) entering the processing chamber (12) through the at least one gas inlet (28, 32).

5. The apparatus (10) according to any one of claims 2 to 4, wherein the shielding element (48) comprises at least one of a substantially plate-shaped element and a shielding gas jet.

6. the transmission element (18) is disposed on a top wall (24) of the processing chamber (12); and / or the flow capture (44) is configured to capture gas containing particulate impurities within a flow capture area (46) disposed adjacent the top wall (24) of the processing chamber (12); and / or the shielding element (48) extends from a top wall of the processing chamber (12) and / or the first rim of the shielding element (48) is connected to a top wall (24) of the processing chamber (12); An apparatus (10) according to any one of claims 1 to 5.

7. 7. The apparatus (10) of claim 1, wherein a flow rate of gas flowing through the at least one gas inlet (28, 32) into the processing chamber (12) is greater than a flow rate of gas containing particulate impurities when trapped in the flow capture region (46).

8. 8. The apparatus (10) of claim 1, further comprising a flow deflecting element (50) configured to deflect a flow of gas containing particulate impurities toward the flow capture area (46) and / or toward the at least one gas outlet (36) of the gas ejection device (34).

9. 9. The apparatus (10) of claim 8, wherein the flow deflection element (50) is positioned adjacent to or integrally formed with a sidewall of the processing chamber (12), specifically above the at least one gas exhaust port (36) of the gas exhaust device (34).

10. The flow deflection element (50) a first section (52) configured to direct a flow of gas containing particulate impurities toward the flow capture area (46), specifically having a first rim connected to a sidewall of the processing chamber (12) and a second rim located opposite the first rim and facing the interior of the processing chamber (12), the first section (52) being inclined with respect to the direction of gas flow (D) entering the processing chamber (12) through the at least one gas inlet (28, 32) such that the first rim is located downstream of the second rim with respect to the direction of gas flow (D) entering the processing chamber (12) through the at least one gas inlet (28, 32); and / or a second section (54) configured to direct a flow of gas containing particulate impurities toward the at least one gas outlet (36) of the gas discharge device (34), specifically having a first rim connected to a sidewall of the processing chamber (12) and a second rim located opposite the first rim and facing the interior of the processing chamber (12), the second section (54) being inclined with respect to the direction of gas flow (D) entering the processing chamber (12) through the at least one gas inlet (28, 32) such that the first rim is located downstream of the second rim with respect to the direction of gas flow (D) entering the processing chamber (12) through the at least one gas inlet (28, 32); and / or a third section (56) extending substantially perpendicular to the direction of gas flow (D) entering the processing chamber (12) through the at least one gas inlet (28, 32) and / or extending between the second rim of the first section (52) and the second rim of the second section (54); 10. The device (10) according to claim 8 or 9, comprising at least one of:

11. The apparatus (10) of any one of claims 1 to 10, further comprising a cooling element (58) configured to cool gas containing particulate impurities trapped in the flow trapping region (46).

12. The apparatus (10) of any one of claims 1 to 11, further comprising a removal device (60) configured to remove gas containing particulate impurities trapped in the flow capture region (46).

13. The apparatus (10) of claim 12, wherein the removal device (60) comprises a connection device (62) connecting the flow capture area (46) to the gas discharge device (34).

14. 1. A method for manufacturing a three-dimensional workpiece, comprising: Applying a layer of raw material powder onto a carrier (14); selectively irradiating the raw material powder on the carrier (14) with electromagnetic or particle radiation to produce a workpiece made from the raw material powder by an additive manufacturing process; transmitting electromagnetic or particle radiation into the processing chamber (12) via a transmission element (18); supplying gas to the processing chamber (12) through at least one gas inlet (28, 32) of a gas supply system (26); exhausting gas from the processing chamber (12) through at least one gas outlet (36) of a gas exhaust system (34); a flow capture (44) for capturing gas containing particulate impurities in a flow capture region (46) located downstream of the transmission element (18) relative to the direction of gas flow (D) entering the processing chamber (12) through the at least one gas inlet (28, 32); The method includes:

15. the flow capture (44) comprises a shielding element (48) disposed downstream of the transmission element (18) with respect to the direction of gas flow (D) entering the processing chamber (12) through the at least one gas inlet (28, 32), and shielding the transmission element (18) from gas containing particulate impurities trapped in the flow capture region (46); and / or 15. The method of claim 14, wherein the flow trap (44) traps gas containing particulate impurities in a flow trapping region (46) disposed adjacent an upper wall of the processing chamber (12).

16. 16. The method of claim 14 or 15, wherein a flow rate of gas flowing through the at least one gas inlet (28, 32) into the processing chamber (12) is greater than a flow rate of gas containing particulate impurities when trapped in the flow capture region (46).

17. 17. The method of claim 14, further comprising: a flow deflecting element (50) for deflecting a flow of gas containing particulate impurities toward the flow capture area (46) and / or toward the at least one gas outlet (36) of the gas discharge device (34), the flow deflecting element (50) being located adjacent to a side wall of the processing chamber (12) or being formed integrally with the side wall of the processing chamber (12), the flow deflecting element being located above the at least one gas outlet (36) of the gas discharge device (34).

18. The flow deflection element (50) a first section (52) configured to direct a flow of gas containing particulate impurities toward the flow capture area (46), specifically having a first rim connected to a sidewall of the processing chamber (12) and a second rim located opposite the first rim and facing the interior of the processing chamber (12), the first section (52) being inclined with respect to the direction of gas flow (D) entering the processing chamber (12) through the at least one gas inlet (28, 32) such that the first rim is located downstream of the second rim with respect to the direction of gas flow (D) entering the processing chamber (12) through the at least one gas inlet (28, 32); and / or a second section (54) configured to direct a flow of gas containing particulate impurities toward the at least one gas outlet (36) of the gas discharge device (34), specifically having a first rim connected to a sidewall of the processing chamber (12) and a second rim located opposite the first rim and facing the interior of the processing chamber (12), the second section (54) being inclined with respect to the direction of gas flow (D) entering the processing chamber (12) through the at least one gas inlet (28, 32) such that the first rim is located downstream of the second rim with respect to the direction of gas flow (D) entering the processing chamber (12) through the at least one gas inlet (28, 32); and / or a third section (56) extending substantially perpendicular to the direction of gas flow (D) entering the processing chamber (12) through the at least one gas inlet (28, 32) and / or extending between the second rim of the first section (52) and the second rim of the second section (54); 18. The method of claim 17, comprising at least one of:

19. 19. The method of claim 14, further comprising removing gas containing particulate impurities trapped in the flow capture area, wherein the removal device specifically comprises a connection device that connects the flow capture area to the gas discharge device.

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