Calibration system for energy beam of additive manufacturing device

Abstract

The invention relates to a calibration system (100, 100 ', 100' ') for an energy beam (22) of an additive manufacturing device (1). The calibration system comprises: an additive manufacturing device (1) having a beam inlet (25) for an energy beam (22); a gas supply source (31) for providing a gas suitable for calibration; and a measuring unit (35) for detecting a beam characteristic of the energy beam (22). Furthermore, the calibration system (100, 100 ', 100' ') comprises calibration aids (40, 60, 80), which have a cavity (54, 74, 94) and an inflow opening (41, 61, 81) for introducing a gas into the cavity (54, 74, 94). In this case, the calibration aid (40, 60, 80) is arranged in the additive manufacturing device (1), and the energy beam (22) is surrounded by a cavity (54, 74, 94) from the beam inlet (25) to the measuring unit (35). A gas is fed into the cavity (54, 74, 94) for calibration. The invention further relates to a method for calibrating an energy beam (22) and to the use of a calibration aid (40, 60, 80) for calibrating an energy beam (22).

Description

Technical Field

[0001] The invention relates to a calibration system and a method as well as the use of a calibration aid for calibrating an energy beam. Background Art

[0002] Additive manufacturing processes are becoming increasingly important in the production of prototypes and at the same time in series production. In general, an "additive manufacturing process" can be understood as a manufacturing process in which a product or component is constructed by accumulating material, usually based on digital 3D design data. The construction process is usually completed by applying the construction material layer by layer and selectively curing it. As a synonym for additive manufacturing, the term "3D printing" is often used, and the production of models, samples and prototypes using additive manufacturing processes is often referred to as "rapid prototyping", mold production is referred to as "rapid tooling", and the production of series products is referred to as "direct manufacturing".

[0003] Selective solidification of building materials is usually achieved by repeatedly applying thin layers of building material, usually in powder form, in a superimposed manner and irradiating spatially limited locations that are to belong to the manufactured product to be produced after manufacturing with the aid of an energy beam, for example with the aid of light and / or heat and / or particle radiation. Examples of methods for processing with irradiation are "laser powder bed fusion" or "selective laser melting". During the solidification process, the powder particles of the building material are partially or completely melted by the energy introduced locally at these locations by the radiation. After cooling, these powder particles are then connected to one another in the form of a solid.

[0004] In such production processes, it is usually necessary to conduct process gases through the process chamber for inertization, cooling or exhaust purposes (especially using fans). This means that the additive manufacturing process is carried out in a process gas atmosphere, the properties of which may differ significantly from the normal ambient atmosphere. For example, the process gas atmosphere can have a lower humidity content than the normal ambient atmosphere.

[0005] Sometimes it is necessary to calibrate the energy beam in order to adjust the properties of the energy beam for manufacturing as best as possible. For this purpose, a measuring instrument is introduced into the beam path, which detects measured values ​​of certain beam properties of the energy beam. In order to provide an atmosphere for calibration that is as identical as possible to that of additive manufacturing, the entire process chamber is currently usually filled with process gas for calibration. This is particularly time-consuming, because multiple calibration steps must be performed and / or the process chamber must first be restored to a normal ambient atmosphere to be safely opened. Summary of the invention

[0006] The object of the present invention is to simplify the calibration of an energy beam of an additive manufacturing device.

[0007] This object is achieved by a calibration system according to claim 1 , a method for calibrating an energy beam according to claim 13 and the use of a calibration aid for calibrating an energy beam according to claim 15 .

[0008] The calibration system for an energy beam of an additive manufacturing device mentioned at the beginning includes an additive manufacturing device having a beam inlet for an energy beam. The calibration system also includes: a gas supply source for providing a gas suitable for calibration; a measuring unit for detecting the beam characteristics of the energy beam; and a calibration aid having a cavity and an inflow opening for introducing a gas into the cavity. Here, the calibration aid is arranged in the additive manufacturing device so that the energy beam is surrounded by the cavity from the beam inlet to the measuring unit, and the gas is fed into the cavity for calibration.

[0009] The energy beam is in principle any energy beam suitable for selectively melting or sintering the corresponding material for additive manufacturing. For example, the energy beam is generated by means of a laser, preferably by means of a CO laser. For example, it can also be a CO2 laser, a diode laser, in particular a diode laser with a wavelength of 4 to 7 μm, an Nd:YAG laser, an electron beam, etc.

[0010] During operation, the energy beam enters the processing chamber or installation space of the additive manufacturing device via (at least one) beam inlet. The beam inlet can be designed in a simple manner as an opening or through hole of the processing chamber. However, in order to keep the volume of the area to be filled with process gas small, the processing chamber is preferably separated from other areas of the additive manufacturing device (such as the optical chamber of the optical element for adjusting the energy beam) in a gas-tight manner. Therefore, the beam inlet is designed, for example, as a coupling-in window that is transparent to the energy beam.

[0011] The gas suitable for calibration is selected according to the energy beam, i.e. according to the type of energy beam. It has optical properties at least similar to those of the process gas. Preferably, in the case of a CO laser as the energy beam, dry air or nitrogen is suitable as calibration gas. For example, the gas is provided by means of a gas cylinder, by means of a separate internal gas supply or preferably by means of a gas supply of the additive manufacturing device.

[0012] The cavity of the calibration aid is surrounded by a hollow body. Here, the hollow body can be substantially formed by corresponding elements of the calibration aid. Alternatively, the hollow body is formed by the interaction of elements of the calibration aid with elements of the additive manufacturing device, such as walls of the process chamber and / or coupling windows or beam inlets. Therefore, during operation as expected, the energy beam is also enclosed from the beam inlet to the measuring unit or measuring instrument. This means that the beam path or light beam path of the energy beam is largely enclosed in the process chamber by the beam inlet, the calibration aid and the measuring instrument. The beam path or light beam path extends through the cavity of the calibration aid. Therefore, the beam path is shielded from the ambient atmosphere in the calibration system, which may have properties that hinder accurate calibration. This improves the repeatability of the calibration.

[0013] For calibration, gas is sent or introduced into the cavity of the calibration aid via the inflow opening. For this purpose, the inflow opening is fluidically connected with a gas supply source, for example, by means of a hose or the like.

[0014] The measuring unit is designed according to the beam characteristic to be detected of the energy beam. When, for example, the power of the energy beam is measured or detected as the beam characteristic by means of the measuring unit, the measuring unit is designed as a power meter. The measuring unit is arranged adjacent to the calibration aid or preferably fastened thereto so that the energy beam strikes the measuring region of the measuring unit.

[0015] Therefore, the calibration aid is preferably an additional unit which can be easily separated from the additive manufacturing device or removed from the process chamber, which additional unit is introduced into the process chamber only for the purpose of calibrating the energy beam.

[0016] Correspondingly, the method mentioned at the beginning for calibrating the energy beam of an additive manufacturing device (including the beam inlet) has at least the following steps: In one step, a calibration aid is provided, which comprises a cavity and an inlet opening for introducing a gas suitable for calibration. In a further step, the calibration aid is introduced into the additive manufacturing device so that the energy beam is largely surrounded by the cavity from the beam inlet to the measuring unit. In a further step, the gas is made to flow through the cavity of the calibration aid. During this period, a calibration of the beam path is performed in a subsequent step. Here, the measuring unit detects the beam characteristics of the energy beam.

[0017] The method thus substantially comprises the functional design features of the calibration system described above.After the calibration has been performed, the calibration aid and the measuring unit are preferably removed from the process chamber so that an additive manufacturing process can be performed by means of the additive manufacturing device.

[0018] As mentioned at the outset, the calibration aid according to the invention is used to calibrate the energy beam of an additive manufacturing device. Here, the calibration aid and its cavity are introduced into the additive manufacturing device so that the energy beam is enclosed in the cavity from the beam inlet to the measuring unit. During the calibration of the beam path, a gas suitable for calibration is flowed through the cavity of the calibration aid and the beam characteristics of the energy beam are detected by means of the measuring unit.

[0019] Thus, the use of the calibration aid in the process chamber of the additive manufacturing device according to the invention advantageously reduces the volume that must be flowed through or filled with the gas suitable for calibration used to calibrate the energy beam, compared to filling the entire process chamber. This reduces the time required for calibration in particular. This is the case in particular if, after a new adaptation of the energy beam, multiple calibration steps and therefore multiple fillings are required.

[0020] Other particularly advantageous designs and improvements of the present invention are derived from the dependent claims and the following description, wherein the independent claims of one category of claims can also be improved similarly to the dependent claims and embodiments of another category of claims, and in particular, the individual features of different embodiments or variants can also be combined into new embodiments or variants.

[0021] Gases suitable for calibration are referred to below as "gases". Preferably, the gas is introduced into the cavity such that during calibration the relative humidity in the cavity remains below 5%, particularly preferably below 4%, very preferably below 3%. As described at the outset, the relative humidity is related, for example, to the beam properties of a CO laser or a diode laser with a wavelength of 4 to 7 μm. Since the relative humidity in the additive manufacturing process is lower similar to the preferred humidity values, it is also advantageous to calibrate the energy beam under these conditions. Preferably, the gas temperature during calibration is at least 10° C. and / or at most 50° C.

[0022] In contrast, during the flow through the cavity, the typical relative ambient humidity prevailing in the remaining volume of the process chamber of the additive manufacturing device is on average preferably greater than 3%, further preferably greater than 5%, even more preferably greater than 10%, and particularly preferably greater than 20%.

[0023] The cavity of the calibration system, i.e. the volume between the beam inlet, the calibration aid and the measuring device, does not have to be sealed gas-tight. Preferably, for example, at the connection points between these individual elements there are small gap dimensions through which the gas can escape. This advantageously allows gas components of the ambient atmosphere to be discharged from the cavity, in particular during the first filling of the cavity with gas.

[0024] Preferably, the gas is provided by means of a gas supply of the additive manufacturing device. This is advantageous because the same gas as in the manufacturing process is used directly and therefore substantially the same optical conditions prevail as in the process gas atmosphere.

[0025] The introduction of gas into the cavity is preferably accomplished via a separate interface or inlet in the process chamber. This means that an additional gas interface or gas inlet for calibration is preferably arranged in the process chamber. Therefore, one or more existing gas inlets to the process chamber, which are used to achieve the inerting of relatively large volumes and / or to clean the process gas of impurities in the process chamber volume, are preferably not used for calibration. Therefore, the inlet for the manufacturing process does not have to be adjusted. In addition, the separate interface for calibration is preferably controllable or adjustable independently of the other inlets. Since the volume flow of the gas used for calibration can be adjusted in this way, it is also possible, for example, to achieve the above-mentioned relative humidity values ​​in the cavity.

[0026] According to an alternative preferred design, a plurality of existing gas inlets in the process chamber are used to provide a gas suitable for calibration. For this purpose, it is particularly preferred that the gas is provided to the additive manufacturing device by means of a flow device assigned to a plurality of beam inlets. In conventional manufacturing processes, the flow device A purging device or a purging device is used for the directional flow of at least one beam inlet or laser window or coupling window. To carry out the calibration, the flow device is activated and controlled or actuated individually, while other devices for filling / flowing the process chamber as a whole with process gas / inert gas can be deactivated during this period. The flow device thus supplies the inlet opening of the calibration aid with a gas suitable for calibration in order to carry out the calibration.

[0027] For example, the cavity of the calibration aid can be docked at the desired location to an opening (gas inlet) on the process chamber side of the flow device and conduct the gas during calibration into the region between the beam inlet or coupling window and the measuring cell. Relative gas tightness can be achieved, for example, by a locally complementary design of the calibration aid with respect to the geometry of the top wall. This means that the calibration aid is connected substantially gas-tightly to the wall or top wall of the process chamber by virtue of its shaping (for example by corresponding positioning and manufacturing accuracy and / or by means of additional seals).

[0028] Preferably, in the desired position, the calibration aid forms a cavity in cooperation with a processing chamber wall of the additive manufacturing device. In this case, the inlet opening of the calibration aid particularly preferably abuts against a gas outlet of the flow device and is fluidically connected thereto.

[0029] Thus, the cavity serves as a gas tube or gas channel and can be realized, for example, by a recess or by designing the calibration aid, which locally comprises a surface spaced apart from the process chamber wall at the intended location. In the intended docking state with the flow conveying device and / or the process chamber ceiling and / or the process chamber wall, the calibration aid according to the invention can form a cavity or thus a clear gap or channel together with the measuring unit. The cavity formed in this way can have an outflow opening, which, during operation as intended, allows the inflowing gas to flow into the interior of the process chamber as the only opening of the calibration aid.

[0030] In this embodiment, advantageous synergistic effects are achieved by virtue of the fact that such a flow device is usually arranged on the ceiling of the process chamber and in the vicinity of the existing plurality of beam inlets or coupling windows. Thus, the flow device is used within the scope of the method or calibration system according to the invention for a further purpose outside the manufacturing process, so that interfaces, valves and / or lines which may be additionally required if necessary are advantageously saved.

[0031] Preferably, the cavity has a variable height. In other words, the distance between the beam inlet and the measuring unit can be adjusted or regulated by means of the cavity, in particular by means of an element forming a hollow body. Thus, for example, the beam characteristics of the energy beam can be calibrated at different height positions of the production plane or the construction field. A detailed design is described below.

[0032] In order to change the height, the cavity is preferably designed to be stretchable. For this purpose, the cavity, i.e. in particular the hollow body, can particularly preferably be made of an elastic material, in particular as a hose. Alternatively or additionally, it can particularly preferably be designed as a bellows or a similar stretchable element. At least the hollow body preferably has a corresponding stretchable area. With this design, on the one hand, the height position of the measuring unit can be changed, but also the position perpendicular to the height in the manufacturing plane can be changed.

[0033] Furthermore, the cavity or the hollow body can be designed particularly preferably as an elastic hood or bellows-shaped hood. Here, the hood has, for example, a pyramidal or conical shape. In contrast to a substantially linear or tubular design of the hollow body, the hood-shaped, pyramidal or conical design allows calibration measurements over the entire construction field without the need to reposition the calibration aid.

[0034] Alternatively or additionally, in order to change the height, the cavity or hollow body is preferably designed to be telescopic. That is, the cavity or hollow body has at least a telescopic part or extension. Here, the cavity or hollow body can also have a rigid part. The extension is, for example, a telescopic extension.

[0035] Preferably, the calibration aid has a joint at at least one end of the hollow body, particularly preferably at each end. For example, a simple pivot joint or a combination of multiple joints can be used as the joint. For example, the joint can also be designed as a bellows. However, it is particularly preferred that the joint is designed as a ball joint. With the help of the joint, in particular in combination with a variable height of the cavity or the hollow body, the measuring unit can be advantageously positioned at different positions on the production plane, in particular different positions required for calibration, with the height of the production plane being adjusted as desired. In this case, the beam path remains surrounded by the hollow body or enclosed in its cavity, so that the energy beam extends during calibration through a gas suitable for calibration.

[0036] The calibration aid is preferably designed to be self-retaining. This means that the calibration aid is preferably designed so that it retains the height and / or the articulated position once it has been adjusted. Therefore, it is particularly preferred that the calibration aid is designed to be self-retaining, so that the calibration aid remains fixed in position / size in the additive manufacturing device.

[0037] This is achieved, for example, by generating a frictional resistance between the individually adjustable elements. The frictional resistance can be generated by relatively small gaps between the elements and / or corresponding surface properties, in particular a suitable surface roughness. The frictional resistance can preferably be overcome simply during manual adjustment, but is sufficient to allow the individual elements to maintain their relative position or arrangement without external influences.

[0038] Preferably, the calibration system has a fastening device for mounting the calibration aid to the additive manufacturing device. The fastening device is arranged, for example, on the calibration aid or the additive manufacturing device. The fastening device is preferably designed as a complementary element of form fit and / or friction fit. For example, the calibration aid can be realized by means of a clamping screw or a clip, in particular by means of a manually releasable form-fitting locking lug, another form-fitting element and / or the like. Here, the calibration aid is preferably fastened in the region of a beam inlet or a coupling window for the energy beam in the process chamber.

[0039] Preferably, the calibration aid extends in the additive manufacturing device over part or the entire distance between the build plane or the construction field and the beam inlet of the additive manufacturing device. This means that the calibration aid is fastened, for example, as described above, to the coupling window and extends from there, but does not extend completely to the build plane, but holds the measuring unit almost floatingly in a position between the build plane and the beam inlet.

[0040] The hollow body of the calibration aid preferably completely surrounds the energy beam from the moment the energy beam passes through the beam inlet or coupling window until the energy beam strikes the measuring unit. Here, the volume enclosed by the hollow body (i.e., the cavity) is preferably smaller than the volume of the process chamber, in particular smaller than one-third of the volume of the process chamber, further preferably smaller than one-quarter, even more preferably smaller than one-tenth, particularly preferably smaller than one-fiftieth, and even more preferably smaller than one-hundredth. This ratio and the resulting savings improve as the size of the installation space increases. Correspondingly, the time required for filling the volume used for calibration according to the invention is also advantageously shorter.

[0041] The calibration aid and / or the measuring unit are preferably removable from the process chamber and are removed from the process chamber before the additive manufacturing process. This means that before commissioning the additive manufacturing device or after a previous additive manufacturing process, the method according to the invention is preferably carried out for calibration, and subsequently the calibration aid and / or the measuring unit are preferably removed from the process chamber and further, a new subsequent additive manufacturing process is carried out.

[0042] This means that the additive manufacturing process is preferably not carried out during the calibration. Therefore, during the calibration with the calibration system according to the invention, it is particularly preferred to deactivate the throughflow of the process chamber, which can be provided, for example, by a circulation system for supplying and returning process gas (if necessary, with filtering of contaminated process gas). This advantageously saves the energy required for process gas or process gas circulation.

[0043] Preferably, the characteristics of the energy beam detected for calibration include the beam power, intensity distribution, focus position, focus geometry and / or response behavior of the energy beam. Alternatively or additionally, the characteristics of the energy beam deflection device (e.g., galvanometer scanner) may also be measured, for example, the position accuracy of one or more deflection devices relative to each other.

[0044] To determine the laser power, a typical power meter is used, for example, as described above. In this case, the laser power is preferably not measured in the focus or focal point, but rather outside the focus point, since the intensity in the focal point can be too high at certain points. If the focus is, for example, in the production plane, the power meter is simply placed on the production plane or the building platform. The resulting offset from the focus is sufficient for the power measurement, since the power meter can still measure the full power in this way without the intensity being too high at certain points.

[0045] The focal position indicates the position of the focal point in three-dimensional space relative to the additive manufacturing device, i.e., in particular the height above the production plane or the distance from the beam inlet and the two-dimensional position in a plane parallel to the production plane. In this case, the focal geometry indicates whether the focal point (in particular when the main axis is indicated) is circular, elliptical or designed in another way. For example, the focal position and the focal geometry can be determined by means of a focus monitor (Fokusmonitor) as a measuring unit. This can be realized in a simple manner, for example, by means of a power meter with a front pinhole (point pinhole aperture).

[0046] The response behavior of the energy beam describes the reaction delay or power curve when switching on, switching off or changing the power requirement. As a measuring unit for the response behavior, for example, thermal paper can be used. On this basis, the corresponding characteristics regarding the response behavior can be determined after a calibration measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The invention will be described in more detail below with reference to the accompanying drawings by means of embodiments. In the various drawings, identical components are provided with identical reference numerals. The drawings are generally not drawn to scale. The drawings show:

[0048] Figure 1 A partial cross-sectional schematic diagram showing an additive manufacturing apparatus for additively manufacturing a three-dimensional object;

[0049] Figure 2 A partial cross-sectional schematic diagram showing an embodiment of a calibration system of the present invention for an energy beam of an additive manufacturing device;

[0050] Figure 3 A schematic detail view showing a partial cross section of another embodiment of the calibration system of the present invention;

[0051] Figure 4 Show Figure 2 A schematic detail diagram of a partial cross section of the calibration system;

[0052] Figure 5 A schematic perspective detail view showing another embodiment of the calibration system of the present invention;

[0053] Figure 6 Show Figure 5 A cross-sectional view of the calibration system;

[0054] Figure 7 Show Figure 5 calibration aids and a 3D detail of the measuring unit; and

[0055] Figure 8 A flow chart of an embodiment of the method of the present invention for calibrating an energy beam of an additive manufacturing device is shown in a block diagram. DETAILED DESCRIPTION

[0056] In the following, reference is made to Figure 1 An apparatus 1 for additive manufacturing of a three-dimensional object is described. Figure 1 The production device 1 shown schematically and partly in section in FIG. 1 is a selectively acting laser melting device 1 . For forming an object 2 , the device comprises a processing chamber 3 with a chamber wall 4 .

[0057] Arranged in the process chamber 3 is an upwardly open container 5 with a container wall 6. A build plane 7 is defined by the upper opening of the container 5, wherein the region of the build plane 7 located within the opening and available for building the object 2 is referred to as a building field 8. Furthermore, the process chamber 3 comprises a process gas supply 31 assigned to the process chamber 3, and a process gas outlet 32.

[0058] In the container 5 there is arranged a carrier 10 which is movable in a vertical direction V, on which a substrate 11 is mounted, which closes the container 5 downwards and thus forms its bottom. The substrate 11 can be a plate formed separately from the carrier 10 and fastened to the carrier 10, or it can be formed integrally with the carrier 10. Depending on the powder and the process used, a building platform 12 can also be mounted on the substrate 11 as a building support, on which the object 2 is built. However, the object 2 can also be built on the substrate 11 itself, which then serves as a building support. Figure 1 , an object 2 to be formed on a building platform 12 in a container 5, located below a production plane 7, is shown in an intermediate state, in which the object has a plurality of solidified layers which are surrounded by building material 13 which remains unsolidified.

[0059] The laser melting device 1 further comprises a storage container 14 for a powdered building material 15 which can be solidified by electromagnetic radiation, and a coater 16 which is movable in a horizontal direction H for applying the stored building material 15 in the building field 8. Preferably, the coater 16 extends transversely to its direction of movement over the entire area to be coated.

[0060] The laser melting device 1 also includes an irradiation device 20 with a laser 21 (preferably a CO laser), which generates a laser beam 22, which is deflected via a deflection device 23 and focused by a focusing device 24 via a beam inlet 25 or a coupling window 25 on the production plane 7, and the coupling window is installed in the chamber wall 4 on the upper side of the processing chamber 3.

[0061] In addition, the laser melting device 1 includes a control unit 29, via which the various components of the laser melting device 1 are controlled in a coordinated manner to perform the construction process. Alternatively, the control unit 29 can also be partially or completely installed outside the laser melting device 1. The control unit can include a CPU, the operation of which is controlled by a computer program (software). The computer program can be stored on a storage medium separately from the laser melting device 1, and the computer program can be loaded from the storage medium into the laser melting device 1, in particular the control unit 29.

[0062] As building material 15 , a powdered material is preferably used, wherein this material can be, for example, a metal-containing or metal-based building material, but preferably a polymer-containing, particularly preferably polymer-based (>50% by weight polymer fraction) building material.

[0063] During operation, in order to apply a powder layer, the carrier 10 is first lowered to a height corresponding to the desired layer thickness. The coater 16 first travels to the storage container 14 and takes out a sufficient amount of building material 15 from the storage container to apply a layer. Subsequently, the coater travels above the building field 8, where the powdered building material 15 is applied to the building support 12 or to the previously existing powder layer and outputs the building material as a powder layer. This application is carried out at least over the entire cross section of the object 2 to be produced, preferably over the entire building field 8 (i.e., the area defined by the container wall 6). Optionally, the powdered building material 15 is heated to the working temperature by means of a radiation heating device.

[0064] Subsequently, the cross section of the object 2 to be produced is scanned with the laser beam 22, so that the powdered structural material 15 is solidified at the location corresponding to the cross section of the object 2 to be produced. Here, the powder particles are partially or completely melted at these locations by means of the energy introduced by the radiation, so that the powder particles are connected to each other after cooling and exist as a solid. These steps are repeated until the object 2 is manufactured and can be removed from the processing chamber 3.

[0065] Figure 2 A schematic partial cross-sectional view of an exemplary embodiment of a calibration system 100 according to the present invention for an energy beam 22, in particular a beam of a CO laser, of an additive manufacturing device 1 is shown. The additive manufacturing device 1 corresponds to Figure 1 1. However, some elements of the additive manufacturing device 1 are not shown here in order to better illustrate the calibration system 100. Here, the carrier 10 and the substrate 11 are arranged adjacent to the production plane 7 or the construction field 8 in the starting position.

[0066] In addition to the additive manufacturing device 1, the calibration system 100 also includes a calibration aid 60 and a measuring unit 35. The measuring unit 35 is designed as a power meter 35 for measuring laser power as a beam characteristic and is positioned in the beam path of the laser beam 22 on the manufacturing plane 7.

[0067] The beam path of the laser 22 in the process chamber 3 is surrounded by a calibration aid 60 from the coupling window 25 to the power meter 35. The calibration aid 60 has an inlet opening 61, which is fluidically connected to the process gas supply 31 by means of a hose 26 and a plug 27 in an exemplary simple embodiment. During calibration, a process gas, in particular nitrogen, flows through the interior or cavity 74 of the calibration aid 60 via the inlet opening (see Figure 4 ), as indicated by the arrows. In this case, the process gas enters through the small gaps between the elements of the calibration aid 60 and discharges gas components of the ambient atmosphere from the calibration aid 60. Since the process gas is the same for the production process and the calibration process, it is a suitable gas for calibration, since it has the same optical properties. For example, a relative air humidity of less than 3% is achieved in the cavity of the calibration aid by the gas fed in, wherein the air humidity (especially in the case of CO lasers) has an influence on the calibration or beam properties.

[0068] The calibration aid 60 will also be used by Figure 4 Detailed description.

[0069] Figure 3 A schematic detail view of a further embodiment of a calibration system 100' according to the invention is shown in partial section. For the sake of clarity, only the production plane 7 of the additive manufacturing device 1 and the upper side of the chamber wall 4 with the coupling window 25 are shown, which separates the irradiation device 20 or the optical chamber from the process chamber 3 in a gas-tight manner by means of a surrounding seal 34 (see also Figure 1 ).

[0070] The calibration aid 40 comprises an upper part 42 and a lower part 43. The upper part 42 and the lower part 43 are substantially cylindrical and arranged concentrically so that they together form a hollow body with a cavity 54. Here, the outer dimensions of the lower part 43 are determined relative to the inner dimensions of the upper part 42 so that they can perform telescopic movements relative to each other. As a result, the height of the calibration aid (i.e. the distance from the free end of the upper part 42 to the free end of the lower part 43) can be changed or adjusted. Preferably, the dimensions of the upper part 42 and the lower part 43 are determined so that they form a friction fit without manual force, which friction fit spontaneously holds the lower part 42 and other components fastened thereto.

[0071] At the free end of the upper half 42, an upper support 44 is formed. The top of the cavity wall 4 has a cornice portion 33 in the area around the coupling window 25. The cornice portion 33 is surrounded by the upper support 44 of the calibration aid 40 in a substantially perfect fit (i.e., only with a small gap size). Therefore, the cornice portion 33 and the upper support 44 have complementary shapes. For example, they can be arranged concentrically, circularly or squarely around the coupling window 25. The upper support 44 is preferably made in a perfectly matching manner so that a friction fit is produced with the cornice portion 33. Thus, a simple plug-in connection is formed. Alternatively, the upper support 44 can also be connected to the cornice portion 33 in a force-fit and / or form-fit manner by a fastening device (such as a clamping screw and / or a buckle).

[0072] The upper part 42 also has an inlet opening 41, which can be fluidically connected to a gas supply source, in particular a process gas supply device 31, for example by means of a hose 26 (see Figure 2 The inflow opening 41 is preferably arranged near or adjacent to the free end of the upper half 42 .

[0073] At the free end of the lower half 42, a lower support 45 is formed. The lower support 45 is manufactured to perfectly match the holder 46 for the measuring cell 35 and surrounds the opening of the measuring cell facing the coupling window 25. Furthermore, "perfect match" preferably means that a friction fit is produced between the lower support 45 and the holder 46, so that a simple plug connection is formed. Alternatively, for example, the above-mentioned fastening means can also be used here.

[0074] The calibration aid 40 is therefore preferably designed such that it maintains the height once adjusted spontaneously and thus also holds the measuring unit 35 in its holder 46 in a manner suspended from the cornice 33. Here, only small gap dimensions occur between the connection points of the elements of the calibration aid 40 with the cornice 33 and the holder 46, through which only a small amount of gas suitable for calibration and introduced via the inlet opening 41 can escape. Therefore, after the initial filling, the cavity 54 is filled with gas suitable for calibration and is easily flowed through by the gas, so that gas from the ambient atmosphere cannot enter the calibration aid 40. Therefore, the entire beam path of the laser beam 22 extending through the process chamber 3 is surrounded by the calibration aid 40 and extends from the coupling window 25 through the gas suitable for calibration until the laser beam strikes the measuring window 36 or the measuring region 36 of the measuring unit 35. Therefore, the laser beam 22 can be calibrated substantially under the same conditions, i.e. with the same optical properties, under which the subsequent additive manufacturing process is also carried out.

[0075] After calibration is complete, the plug-in connection of the calibration aid 40 (and, if necessary, its fastening means) to the cornice 33 and the support 46 can be released and the calibration aid 40 can be removed from the processing chamber 3. To facilitate removal, the calibration aid 40 can be pushed together between its upper half 42 and its lower half 43, for example when using a telescopic height adjustment.

[0076] exist Figure 4 In the Figure 2 Schematic cross-sectional view of a calibration system. The calibration aid 60 shown here is Figure 3 The calibration aid 40 of FIG. 6 is similar to the calibration aid 40 of FIG. 60 . However, the difference is that the calibration aid 60 has two ball joints 68 , 69 , 70 , 71 , 72 , 73 .

[0077] The upper ball joint 68, 69, 70 is formed between the upper support 64 and the upper half 62. The upper ball joint comprises a concentrically arranged intermediate spherical crown 68, an outer spherical crown 69 and an inner spherical crown 70. Here, the spherical crowns 68, 69, 70 are designed as spherical universal joints or layers of spherical universal joints and have radii that increase from the inside to the outside relative to each other. The outer spherical crown 69 and the inner spherical crown 70 are formed on the upper support 64. The intermediate spherical crown 68 is formed on the upper half 62. Compared with the outer spherical crown 69 and the inner spherical crown 70, the intermediate spherical crown is designed as a spherical layer that is closer to the pole of the sphere and is therefore partially engaged between the outer spherical crown 69 and the inner spherical crown 70. Therefore, the upper half 62 is supported movably or rotatably around the common center of the spherical crowns 68, 69, 70 relative to the upper support 64. For example, such a rotary bearing 68 , 69 , 70 consisting of spherical crowns 68 , 69 , 70 joined together can be produced by means of additive manufacturing.

[0078] Between the lower support 65 and the lower half 63, lower ball joints 71, 72, 73 are formed in the same manner as the upper ball joints 68, 69, 70. Here, the intermediate spherical crown 71 arranged on the lower half 63 also engages between the inner spherical crown 73 and the outer spherical crown 72, both of which are formed on the lower support 65. Preferably, similar to a telescopic connection, the two ball joints 68, 69, 70, 71, 72, 73 are formed in a self-retaining manner between the upper half 62 and the lower half 63 by virtue of the friction resistance existing therebetween.

[0079] By means of ball joints 68, 69, 70, 71, 72, 73, measuring unit 35 can be positioned at a position on central vertical axis A of coupling window 25 with an offset D. This also allows the beam characteristics of laser beams 22 which extend obliquely to central vertical axis A at an angle α to be calibrated.

[0080] exist Figure 5 and Figure 6 Another embodiment of the calibration system 100 of the present invention is schematically shown in a three-dimensional diagram. Figure 6 Display along Figure 5 4. Here, for the sake of clarity, only the top of the chamber wall 4 is partially shown.

[0081] A coupling window 25 is arranged in a recess at the top of the chamber wall 4. Via the coupling window 25, the laser beam 22 strikes a measuring region 36 of a measuring unit 35 which is arranged in the processing chamber 3 (see Figure 1 ). The measuring unit 35 also has a fan 37 with cooling fins in order to dissipate the generated heat if necessary.

[0082] The measuring unit 35 is fastened in the vicinity of the coupling window 25 by means of a calibration aid 80. For precise positioning and fastening, the calibration aid 80 has two pins 84 (see Figure 6 and 7 ), which engage in a form-fitting manner in complementary elements (not shown) that are rigidly connected to the chamber wall 4. With the help of the pins 84 and the complementary elements, the calibration aid 80 and therefore also the measuring unit 35 are precisely guided to the position required for the measurement. In addition, for fastening, metal plates 26 are arranged on both sides next to the coupling window 25 parallel to the section plane S. The metal plates 26 are accordingly surrounded by the fastening clamps 82 of the calibration aid 80. With the help of the fastening clamps 82 and the corresponding knurled screws 83, the calibration aid 80 is fastened to the metal plates 26 in a force-fitting manner.

[0083] A cavity 94 is arranged between the coupling window 25 and the measuring region 36 of the measuring cell 35, which cavity is surrounded by the hollow body of the calibration aid 80. Figure 3 and Figure 4 Compared to the embodiment of the present invention, the cavity 94 is designed to be flat so that the gas suitable for calibration flows through it in a substantially laminar flow. Figure 7 As shown, it schematically shows Figure 5 and Figure 6 A perspective view of a calibration aid 80 is shown in FIG. 8 , in which the measuring unit 35 is shown without the chamber wall 4 .

[0084] In order to introduce gas into the cavity 94, the calibration aid 80 has an inlet opening 81. Preferably, the inlet opening 81 is directly fluidically connected to a gas supply (not shown). Here, the gas supply is preferably not a process gas supply provided for the actual circulation of the process gas. The gas supply used here is preferably designed separately from the process gas supply and preferably controlled separately.

[0085] Thus, the laser beam 22 extends between the coupling-in window 25 and the measuring region 36 of the measuring cell 35 in a cavity 94 which is surrounded by the calibration aid 80 and through which a gas suitable for calibration flows during calibration. The laser beam 22 is thus shielded from gases in the ambient atmosphere which could have a negative effect on the calibration.

[0086] Although Figure 3 and Figure 4 The calibration aids 40, 60 are particularly suitable for performing a calibration based on beam characteristics detected in the region of the production plane 7, but Figures 5 to 7 The calibration aid 80 illustrated in FIG. 8 has an advantageously small volume to be filled and is used for calibration measurements which can be performed in the region of the coupling window 25 , for example, measuring the total power of the laser beam 22 .

[0087] Figure 8 A flow chart of an exemplary embodiment of the method according to the present invention for calibrating an energy beam 22 of an additive manufacturing device 1 is shown in a block diagram.

[0088] In a first step I, a plurality of additive manufacturing processes are performed by means of the additive manufacturing device 1. After a predetermined number of manufacturing cycles, a predetermined operating time or as required, the energy beam 22 needs to be calibrated.

[0089] For this purpose, in a second step II, a calibration aid 40 , 60 , 80 is provided which has a hollow body 54 , 74 , 94 with an inflow opening 41 , 61 , 81 .

[0090] In a third step III, the calibration aid 40 , 60 , 80 is introduced into the process chamber 3 of the additive manufacturing device 1 , so that the calibration aid surrounds the energy beam from the coupling window 25 or the beam inlet 25 to the measuring unit 35 for subsequent calibration.

[0091] The inflow opening 41 , 61 , 81 is fluidically connected to a gas supply source, so that in a fourth step IV a gas suitable for calibration flows through the hollow body 54 , 74 , 94 .

[0092] In this gas atmosphere, calibration is performed in a fifth step V. For this purpose, beam characteristics, such as the power of the energy beam 22, are detected by means of a measuring unit 35, such as a power meter. Based on the values ​​measured in this way, the optical devices 22, 23 are adjusted or adjustments are made during the generation 21 of the energy beam 22 until the desired beam characteristics are achieved.

[0093] In a sixth step VI, after calibration, the calibration aid 40 and the measuring unit 35 are removed from the process chamber 3 .

[0094] In a seventh step VII, multiple manufacturing processes can be performed with the calibrated energy beam 22 until recalibration is required and steps II to VI are repeated.

[0095] Finally, it is pointed out again that the drawings described in detail above are only embodiments, and various modifications may be made thereto by those skilled in the art without departing from the scope of the invention. Although only CO lasers are described above as energy beams and nitrogen as a gas suitable for calibration, other types of lasers and corresponding suitable gases or gas mixtures also fall within the scope of the invention. The calibration aid may also have other designs, such as a bellows shape, etc. In addition, the use of the indefinite article "a" or "an" does not exclude that the relevant features may exist in plurality. Similarly, the term "unit", "device" or "system" does not exclude that it is composed of a plurality of subcomponents that cooperate with each other, which may also be spatially distributed if necessary.

[0096] Reference numerals list

[0097] 1Additive manufacturing device / laser melting device

[0098] 2 Objects / Components

[0099] 3 Processing chamber

[0100] 4 Cavity wall

[0101] 5. Container

[0102] 6 container wall

[0103] 7. Manufacturing Plane

[0104] 8 Tectonic Field

[0105] 10 Carrier

[0106] 11 base plate

[0107] 12 Construction Platform

[0108] 13 Uncured construction material

[0109] 14 Storage Containers

[0110] 15 Construction Materials

[0111] 16 Coating Machine

[0112] 17 Radiant heating device

[0113] 20 Irradiation device / irradiation device

[0114] 21 Lasers

[0115] 22 laser beams, beam paths

[0116] 23 Deflector / Scanner

[0117] 24 Focusing device

[0118] 25 Incoupling window / beam entrance

[0119] 26 Metal Plate

[0120] 28 Hose

[0121] 27 plug

[0122] 29 Control Unit

[0123] 31. Process gas supply device

[0124] 32 Process gas outlet

[0125] 33 Cornice

[0126] 34 Seals

[0127] 35 measurement units

[0128] 36 measurement areas / measurement windows

[0129] 37 Fan

[0130] 40, 60, 80 calibration aids

[0131] 41, 61, 81 inflow openings

[0132] 42, 62 upper part

[0133] 43, 63 lower part

[0134] 44, 64 upper support

[0135] 45 Lower support

[0136] 46 Bracket

[0137] 54, 74, 94 cavity / hollow body

[0138] 68, 71 middle ball crown

[0139] 69, 72 outer ball crown

[0140] 70, 73 inner ball crown

[0141] 68, 69, 70 upper ball joint

[0142] 71, 72, 73 lower ball joint

[0143] 82 Fastening clip

[0144] 83 Knurled Screw

[0145] 84 Pins

[0146] 100, 100', 100" Calibration System

[0147] A axis

[0148] α Angle

[0149] D Offset

[0150] V vertical direction

[0151] Section plane S

[0152] I, II, ..., VII method steps.

Claims

1. A calibration system (100, 100', 100") for an energy beam (22) of an additive manufacturing device (1), the calibration system comprising: - an additive manufacturing device (1) having a beam inlet (25) for the energy beam (22), - a gas supply source (31) for providing a gas suitable for calibration, - a measuring unit (35) for detecting the beam characteristics of the energy beam (22) and - a calibration aid (40, 60, 80) having a cavity (54, 74, 94) and an inflow opening (41, 61, 81) for introducing the gas into the cavity (54, 74, 94), wherein - the calibration aid (40, 60, 80) is arranged in the additive manufacturing device (1), the energy beam (22) is enclosed in the cavity (54, 74, 94) from the beam inlet (25) to the measuring unit (35), and - The gas used for the calibration flows into the cavity (54, 74, 94).

2. A calibration system according to claim 1, wherein the gas is introduced into the cavity (54, 74, 94) so ​​that during the calibration, the relative humidity in the cavity (54, 74, 94) is kept below 5%, preferably below 4%, particularly preferably below 3%.

3. The calibration system according to one of the preceding claims, wherein the gas is provided by means of the gas supply source (31) of the additive manufacturing device (1).

4. The calibration system according to one of the preceding claims, wherein the cavity (54, 74, 94) has a variable height.

5. The calibration system according to any of the preceding claims, wherein the cavity (54, 74) is telescopic to vary the height.

6. A calibration system according to claim 5, wherein the calibration aid (60) has a joint (68, 69, 70, 71, 72, 73) at at least one end of the cavity (74), preferably at each end, and the joint is preferably designed as a ball joint (68, 69, 70, 71, 72, 73).

7. The calibration system according to one of the preceding claims, wherein the gas is supplied to the additive manufacturing device (1) by means of a flow device which is assigned to a plurality of beam inlets (25).

8. A calibration system according to one of the preceding claims, wherein in the expected position, the calibration aid (80) forms the cavity (94) by cooperating with the processing chamber wall of the additive manufacturing device (1), wherein the inlet opening (81) of the calibration aid (80) is preferably adjacent to the gas outlet of the flow conveying device.

9. The calibration system according to one of the preceding claims, wherein the calibration aid (40, 60, 80) is designed to be self-retaining.

10. The calibration system according to one of the preceding claims, wherein the calibration aid (40, 60, 80) is designed to be self-retaining, so that the calibration aid remains positionally / size-fixed in the additive manufacturing device (1).

11. The calibration system according to one of the preceding claims, comprising fastening means (82, 83, 84) for mounting the calibration aid (80) to the additive manufacturing device (1).

12. The calibration system according to claim 1, wherein the calibration aid (40, 60, 80) extends in the additive manufacturing device (1) over a portion or the entire distance between a build plane (7) and a beam inlet (25) of the additive manufacturing device (1).

13. A method for calibrating an energy beam (22) of an additive manufacturing device (1), the additive manufacturing device comprising a beam inlet (25), the method comprising at least the following steps: - providing a calibration aid (40, 60, 80) having a cavity (54, 74, 94) and an inflow opening (41, 61, 81) for introducing a gas suitable for the calibration, - introducing the calibration aid (40, 60, 80) into the additive manufacturing device (1) so that the energy beam (22) is surrounded by the cavity (54, 74, 94) from the beam inlet (25) to the measuring unit (35), - causing the gas to flow through the cavity (54, 74, 94) of the calibration aid (40, 60, 80) and - performing the calibration of the energy beam (22), wherein the measuring unit (35) detects beam characteristics of the energy beam (35).

14. The method according to claim 13, wherein, in order to achieve the calibration, the beam power, the intensity distribution, the focus position, the focus geometry and / or the response behavior of the energy beam are detected as beam characteristics of the energy beam (22).

15. Use of a calibration aid (40, 60, 80) for calibrating an energy beam (22) of an additive manufacturing device (1), wherein - introducing the calibration aid (40, 60, 80) and its cavity (54, 74, 94) into the additive manufacturing device (1) so that the energy beam (22) is surrounded by the cavity (54, 74, 94) from the beam inlet (25) to the measuring unit (35), - causing a gas suitable for the calibration to flow through the cavity (54, 74, 94) of the calibration aid (40, 60, 80) and - performing the calibration of the energy beam (22), wherein the measuring unit (35) detects beam characteristics of the energy beam (22).

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