Support system for manufacturing system and workpiece holder for the same

Abstract

To provide a support system for a manufacturing system, and a workpiece holder for use in the support system.SOLUTION: A support system comprises: a base support that is designed to be mounted to a process chamber of a manufacturing system and that has at least one positioning element; and a workpiece holder on which a workpiece can be fabricated according to the manufacturing process involving layered application of a powdered raw material. The workpiece holder has a lower side and a build side as an upper side; the workpiece holder has a positioning device on its lower side in order to releasably, positionally and precisely attach the workpiece holder to the base support of the manufacturing device; the positioning device is designed in a complementary fashion to form pin / hole pairs; at least one portion of the pin is made from a first material having a first coefficient of thermal expansion; and a hole portion is made from a second material having a second coefficient of thermal expansion.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The invention relates to a support system for a manufacturing system and to a workpiece holder thereof according to the preamble of claim 1. The invention further relates to a manufacturing device comprising such a support system and to a method for producing a workpiece. [Background technology]

[0002] In additive manufacturing, also called "3D printing", a workpiece is built up step by step from a build material. For this purpose, in one variant, a powder of the build material is applied layer by layer to a build platform ("stage"). This powder is melted in a controlled manner by inputting energy. Once the melted areas have solidified, the process is repeated until the workpiece is complete. The energy is applied, for example, by targeted irradiation with electromagnetic radiation, more particularly with a laser, or with particle radiation. The layer-by-layer application of the powder is achieved, for example, by lowering the build platform step by step in a build cylinder. An apparatus of this kind is known, for example, from EP 2 386 404 (A1).

[0003] For precise, high-quality production, the powder application must be uniform and dense. In particular, local sagging of the building material during the production process must be avoided. Possible causes of this are small voids that collapse during the process. Irregularities in the respective top layers lead to structural defects in the produced workpiece.

[0004] Another aspect of the above manufacturing process is the complete sealing of the build platform to the build cylinder, avoiding loss of build material into the space below the build platform due to leakage of this seal, which may result in undesirable unevenness in the applied build material layer.

[0005] Various building materials are known for use in these additive manufacturing processes, in particular meltable or partially meltable materials such as polymers, more particularly thermoplastic polymers, metal powders, ceramic powders, etc.

[0006] Once the manufacturing process is complete and excess build material is removed, the workpiece is rigidly secured to the build platform at its contact surfaces and often through support structures that serve to stabilize the position of the workpiece during the manufacturing process and to direct generated heat to the build platform.

[0007] Such workpieces produced by additive manufacturing processes are often in a state where they must be followed by further process steps, e.g. thermal treatments, or cutting (i.e. material removal or removal) manufacturing processes. For this purpose, it is necessary to remove the workpiece from the build platform so that these further process steps can be applied. Since the build platform is an integral part of the additive manufacturing apparatus and removing it therefrom is laborious, the removal of the workpiece from the platform must be done on-site, which is complex and typically requires manual labor. Furthermore, since multiple objects (e.g. up to 100) are produced simultaneously, it is difficult to access the individual workpieces during removal.

[0008] From the field of cutting manufacturing (turning, milling, grinding, etc.) it is known to arrange exchangeable workpiece holders, so-called pallets, on a base plate. The pallets are provided with suitable fixing devices for the workpieces, and more recently also with so-called zero-point clamping systems, by which displacements of the pallet relative to its centre due to thermal expansion during processing and mechanical loads applied to the pallet are avoided. The pallets are fixed to the base carrier by active fixing devices so as to withstand the loads during processing.

[0009] However, pallets of this kind are not applicable to additive manufacturing processes, in particular those using powders applied in layers, in particular they do not meet certain requirements, namely compatibility with the build material so that the workpieces can be built on the surface of the pallet, a void-free coating with powder with maximum use of the surface, since additive manufacturing allows the simultaneous production of several workpieces on the one hand, and on the other hand, due to the high time requirements, a large number of workpieces produced simultaneously is a determining factor for profitability, and dimensional stability during heating, since in additive manufacturing, due to the direct connection of the build surface to the workpiece, deformations of the build surface are directly transmitted to the workpiece. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] EP2386404(A1) Summary of the Invention [Problem to be solved by the invention]

[0011] It is therefore an object of the present invention to provide a solution in the form of a support system, a workpiece holder and associated methods that allows a more streamlined transfer of a workpiece from a manufacturing apparatus for an additive manufacturing process to a subsequent manufacturing process, more particularly to a subsequent removal process (e.g. a cutting process) or a subsequent thermal process. [Means for solving the problem]

[0012] Such a support system is described in claim 1 and a workpiece holder is described in claim 2. Claims 15 to 19 each define a corresponding method for producing a workpiece. The further claims show preferred embodiments and a manufacturing device.

[0013] Each of the numerical values ​​set forth in the following description and claims should be understood to include normal tolerances.

[0014] According to a first aspect, a support system for a manufacturing apparatus and a workpiece holder for such a support system are provided. The support system comprises a base support (or base plate) designed to be mounted in a process chamber of the manufacturing system and comprising at least one positioning element, and a workpiece holder on which a workpiece can be fabricated according to a manufacturing process comprising layer-by-layer application of powdered raw materials. The workpiece holder has a lower side and a build side as the upper side of the workpiece holder, which is substantially opposite the lower side. On the lower side, the workpiece holder has at least one first positioning device for releasably and positionally accurately mounting the workpiece holder to the base support of the manufacturing apparatus. The at least one positioning element and the at least one first positioning device are designed in a complementary manner and form a pin / hole pair. At least one part of the pin is made of a first material having a first thermal expansion coefficient, and a part of the hole, which is crucial for the positioning accuracy, is made of a second material having a second thermal expansion coefficient. In the first option, the second coefficient of thermal expansion is smaller than the first coefficient of thermal expansion, so that when the temperature of the support system increases during the manufacturing process, a clamping effect occurs between the pin and the surrounding hole due to expansion of the area of ​​the pin. In the second option, the first coefficient of thermal expansion is smaller than the second coefficient of thermal expansion, so that when the temperature of the support system increases during the manufacturing process, a clamping effect occurs between the pin and the surrounding hole due to expansion of the retention area of ​​the hole.

[0015] The manufacturing system may for example be an additive type (e.g. for selective laser melting) manufacturing device. The manufacturing system may also be a manufacturing system for thermal post-treatment of workpieces or a manufacturing system for subtractive (e.g. cutting) manufacturing. The process chamber may be the space of the manufacturing system in which the respective manufacturing process (e.g. additive manufacturing process) is performed. More specifically, the base support may be provided as part of the build platform of the manufacturing system. The base support may include fastening means suitable for fastening the base support to a base plate of the manufacturing system. Such fastening means may for example be holes, pins and / or screws. In particular, the base support may be adapted to be screwed to the base plate of the manufacturing system.

[0016] The manufacturing process may include, for example, selective laser melting or selective laser sintering. The powdered raw material may be a metal powder. The lower side and the upper side of the workpiece holder may be provided as substantially flat surfaces of the workpiece holder and may define both sides of the workpiece holder. The build side may be suitable for manufacturing a workpiece thereon according to a method including layer-by-layer application of the powdered raw material. The first positioning device may have a circular cross section or a cross section deviating from a circular shape. A plurality of first positioning devices may be provided on the workpiece holder (e.g. in the form of an array of positioning devices). Furthermore, a plurality of positioning elements may be provided on the base support (e.g. in the form of an array of positioning elements). The number of positioning devices may differ from the number of positioning elements. The positioning element and the first positioning device configured as a pin / hole pair may mean that the positioning element is designed as a pin and the first positioning device is designed as a hole or that the positioning element is designed as a hole and the first positioning device is designed as a pin. In other words, the pin / hole pair is designed such that the base support comprises the pin and the workpiece holder comprises the hole, or the base support comprises the hole and the workpiece holder comprises the pin. If multiple pin / hole pairs are provided, the base support may comprise both the pin and the hole and the workpiece holder may comprise the associated hole and pin. The positioning element and the first positioning device being complementary in design may mean that the cross-section of the positioning element substantially matches the cross-section of the first positioning device. In other words, the pin can be received in the hole with substantially no play.

[0017] At least one section of the pin can be a positioning ring. The positioning ring can have a substantially annular shape. The positioning ring can be provided, for example, in the form of a disk-shaped ring. The thickness of the positioning ring can be, for example, constant. At least one section of the pin can also be provided in the form of a cylinder. The thermal expansion coefficient can be a longitudinal expansion coefficient or a spatial expansion coefficient. According to a first option, the clamping effect can be achieved, for example, by a section of the pin expanding in the radial direction of the pin, thus involving friction and positive interlocking between the pin and the hole. According to a second option, the clamping effect can be achieved, for example, by a holding section of the hole expanding in the (negative) radial direction of the hole, i.e. towards the pin, thus involving friction and positive interlocking between the pin and the hole.

[0018] A positive connection can be achieved, for example, in a direction parallel to the upper and lower sides, and a friction connection can be achieved in a direction perpendicular to the upper and lower sides. When the support system cools down, the clamping effect can be released.

[0019] The workpiece holder may comprise a plate-shaped upper element and a plate-shaped lower element. The upper element may comprise an upper side and the lower element may comprise a lower side. The upper element may be formed from a different material than the lower element.

[0020] Hereinafter, the lower element is also called the lower part and the upper element is also called the upper part. Between the upper and lower sides of the workpiece holder there may be an interface between the upper and lower elements. At this interface the upper and lower elements may contact each other in a planar manner. However, a cavity or multiple cavities may also be provided between the upper and lower elements.

[0021] The upper and lower elements are each plate-shaped. Also, at the interface of the two elements, the upper and lower elements can have the same cross section (e.g. a substantially rectangular cross section). The upper element is made of a different material than the lower element. For example, the upper element can be made of a material suitable for producing workpieces by a manufacturing process, more particularly by a (selective laser melting) process. The upper element can be made of, for example, aluminum or an aluminum alloy. The lower element can be made of a heat-resistant material. The lower element can be made of, for example, tool steel.

[0022] The lower and upper elements may be releasably connected to one another. Thus, the lower and upper elements may, for example, be screwed together. Alternatively, the two elements may be connected to one another by other releasable fastening devices, for example by pegs or pins and associated holes, or by clamps.

[0023] Starting from the upper side, at least 1 / 4 of the height of the workpiece holder can form the upper element, and starting from the lower side, the lower element can extend up to the upper element, in which at least a part of the first positioning device is formed, for example in the form of a hole. The upper element can for example form up to 3 / 4 of the height of the workpiece holder, for example about half of the height of the workpiece holder.

[0024] The second material is - Heat resistant up to 550℃ - Hardness ranging from 45 to 68HRC (Rockwell Hardness C) The stimuli can exhibit at least one of the following two characteristics:

[0025] The second material may furthermore be heat resistant up to 1000° C. The hardness of the second material may for example be in the range of 50 to 55 HRC. This material may be a tool steel. The entire lower element may for example be made of the material of which the holding parts of the first positioning device, which are relevant for the positioning accuracy, are made.

[0026] The first positioning devices may be substantially holes and the retention portions of the holes may represent substantially annular portions of the inner walls of the holes. The retention portions may comprise at least one ring per hole that is pressed or screwed into.

[0027] If the holding portion comprises a pressed or screwed ring, the ring may, for example, be formed from the second material and the rest of the workpiece holder may be formed from another material, which may, for example, be a material suitable for fabricating the workpiece thereon by a manufacturing process.

[0028] The second positioning device may be provided on the upper element and the lower element and may have a configuration complementary to each other, so that the upper element and the lower element may be positionally accurately fixed to each other. The second positioning device may have at least two pairs of holes, including a first hole and at least one second hole, and the second hole is designed as an oblong hole, so that a positioning pin of the second positioning device inserted therein is displaceable in at least one direction to compensate for thermal dimensional changes of the upper element relative to the lower element. More specifically, the oblong hole may extend in a direction substantially corresponding to the direction connecting between the first hole and the second hole.

[0029] Since the first positioning device can represent a hole with a circular cross section and a second recess arranged offset from the center is provided in the workpiece holder, or since the hole has an elliptical, oval or polygonal cross section, the workpiece holder is rotationally constrained when placed on a base support having at least one positioning element of a complementary configuration. In particular, the workpiece holder should be rotationally constrained relative to the base support in a direction parallel to the upper and lower sides of the workpiece holder. For this purpose, for example, a polygonal cross section of the first positioning device can be advantageous.

[0030] The side surface of the workpiece holder between the lower side and the upper side may be inclined, so that the workpiece holder tapers from the lower side towards the upper side. The inclined side surface ensures that agglomeration of the powdered building material due to compression due to thermal expansion of the workpiece holder is avoided. Furthermore, the risk of voids being generated in the powdered building material applied to the workpiece holder is avoided. The inclination of the side surface may, for example, be in the range of 1° to 11°, in particular 3° to 9°, more particularly 5° to 7°, for example up to 6°.

[0031] At least one side of the workpiece holder can be provided with at least one gripping means in the form of a groove or a ridge. The gripping means can extend from top to bottom, i.e. from the upper side to the lower side. The gripping means can be designed such that the gripping device can engage with it and be fixed there by friction and / or a positive connection so as to be able to move the workpiece holder.

[0032] The gripping means may be designed in the form of a groove with a dovetail cross section. The side walls of the gripping means may each have an undercut of from 10° to 40°, in particular from 15° to 20°.

[0033] The at least one positioning element can comprise a pin, the at least one positioning device can comprise a hole, and the lower element is formed from a second material. The second material of the lower element can be a tool steel.

[0034] According to a second aspect there is provided an additive manufacturing apparatus using a manufacturing process comprising layer-by-layer application of powdered raw material, the manufacturing apparatus comprising a build stage and a support system according to the first aspect, the build stage of the manufacturing apparatus comprising a base support of the support system, the base support may for example be screwed to a base plate such that the base support represents part of the build stage of the manufacturing apparatus.

[0035] The base support may comprise an array of positioning elements, including pins of circular cross section and additional rotationally restraining pins. Alternatively, the pins may have an elliptical, oval or polygonal cross section such that the workpiece holder is restrained from rotating when placed on the base support. In particular, the workpiece holder should be restrained from rotating in directions parallel to the upper and lower sides of the workpiece holder.

[0036] According to a third aspect, a method for fabricating a workpiece is provided. The method includes placing a workpiece holder of a support system according to the first aspect on a base support of a support system of an additive manufacturing device, where at least one positioning element comprises a pin and at least one positioning device comprises a hole, and the pin engages with the hole. The method further includes performing additive manufacturing of the workpiece on the workpiece holder by the manufacturing device, where the temperature of the support system increases during the manufacturing process and a clamping effect occurs between the pin and the surrounding hole due to expansion of the area of ​​the pin or expansion of the holding area of ​​the hole, cooling the support system, whereby the clamping effect is released, disengaging the workpiece holder together with the workpiece fabricated thereon from the base support, and placing the workpiece holder on a support of a system for subtractive post-processing of the workpiece, where the pin of the support engages with the hole of the workpiece holder.

[0037] The method may further comprise a step of placing the workpiece holder on a support of an equipment for thermal post-treatment of the workpiece prior to the step of placing the workpiece holder on a support of an equipment for ablation post-treatment. The thermal post-treatment may be, for example, a heating treatment. The material of the lower element of the workpiece holder may be heat-resistant to the heat generated by the equipment. During the thermal post-treatment, the aforementioned clamping effect between the holes of the workpiece holder and the pins of the base support of the system for thermal post-treatment may also be utilized.

[0038] The disengaging step may include gripping the workpiece holder with a gripping tool by gripping means provided on a side of the workpiece holder, which may for example be a dovetail groove.

[0039] A plurality of workpiece holders may be arranged side-by-side, possibly spaced apart, on a base support of a manufacturing apparatus, such that, for example, the entire surface of the base support is covered by workpiece holders, and in a manufacturing process, a workpiece may be fabricated, for example, on each of the workpiece holders.

[0040] According to a fourth aspect, there is provided a method for fabricating a workpiece according to an additive manufacturing process, the method comprising: determining a position and / or orientation of a workpiece to be fabricated relative to a workpiece holder on which the workpiece is additively manufactured taking into account digital part data defining a geometry of the workpiece and taking into account conditions defined by a subtractive post-processing of the workpiece, and performing additive manufacturing of the workpiece on the workpiece holder based on the determined position and / or orientation of the workpiece.

[0041] The method may be performed, for example, by a control device of an additive manufacturing device. The method may also be provided by a central control device or a central computer configured to control both the additive manufacturing device and the device for subtractive post-processing. The control device and / or computer performing the method may comprise a processor for performing the individual process steps and a memory in which program instructions for the individual process steps are stored. The digital part data may be CAD (Computer Aided Design) data, more specifically a machine-readable CAD file. The method may include a step of generating a machine control file for additive manufacturing, based on which the step of performing additive manufacturing is performed. The machine control file may include information regarding the determined position and / or orientation of the workpiece.

[0042] The method may further include determining a support geometry including at least one support structure for the workpiece taking into account conditions defined by a subtractive post-processing of the workpiece, and performing additive manufacturing includes additive manufacturing of the support structure. The support structure may specifically include one or more supports and / or columns for the workpiece that support the workpiece on the workpiece holder. The method may include generating a machine control file for additive manufacturing, the machine control file including and / or defining information regarding the support structure.

[0043] The conditions defined by the subtractive post-processing of the workpiece may include at least one of the following conditions: milling force of the tool used in subtractive post-processing, milling torque of the tool used in subtractive post-processing, vibration during subtractive post-processing, attainability of the geometry of the workpiece and / or the support structure by the tool used in subtractive post-processing, machine kinematics of the tool used in subtractive post-processing, tool geometry of the tool used in subtractive post-processing, tool coordination of the tool used in subtractive post-processing. These conditions may be stored, for example, in a memory and thus known to the machine performing the method. These conditions may be provided, for example, in the form of parameters or numerical data.

[0044] The method may further include configuring an available build space of the manufacturing device for additive manufacturing of the workpiece.

[0045] The method may further include determining layer thicknesses for additive manufacturing and / or determining an exposure strategy for additive manufacturing taking into account digital part data defining a geometry of the workpiece and taking into account conditions defined by subtractive post-processing of the workpiece. In other words, both layer thicknesses and exposure strategy may be determined taking into account the digital part data. The exposure strategy may, for example, define locations of multiple exposure passes.

[0046] The method may further comprise the step of providing a support system according to the first aspect, the workpiece holder being a workpiece holder of the support system.

[0047] As explained above, the workpiece holder according to the first aspect can differentiate itself in that at least those surfaces on which the workpieces are produced by additive manufacturing consist of the material on which production is possible. In the simplest case, the surface consists substantially of the material used for production.

[0048] The workpiece holders according to the first aspect may be provided with corresponding positioning devices, preferably holes, on their underside for mounting on a base plate of a correspondingly equipped manufacturing device, and the workpiece holders may then be arranged on a base plate with complementary positioning devices, i.e. preferably pins.

[0049] In a preferred embodiment, the functionally significant parts of the positioning device of the workpiece holder are made of a heat-resistant (e.g. up to 500° C.) and / or hardenable or hardened material. The workpiece holder can therefore be exposed to heating procedures together with the workpiece or can withstand the loads caused by clamping during cutting or material removal procedures, respectively. A suitable material is tool steel.

[0050] Heat resistance means that sufficient mechanical properties, especially strength, are maintained even at a certain high temperature (e.g. 500°C or 900°C). As a parameter of heat resistance, a 0.2% yield point, i.e. the stress causing a reversible elongation of 0.2%, can be used. Depending on the requirements, a 0.2% yield point at least 10 MPa, preferably 20 MPa, or higher, e.g. 30 MPa or 40 MPa, can be considered as a limit for heat resistance.

[0051] The positioning device may be an insert that is threaded or pressed into a hole in the body of the workpiece holder.

[0052] In a particularly preferred embodiment, the upper part (upper element) of the workpiece holder is made from a material compatible with additive manufacturing, and the lower part (lower element) is made from a material appropriately selected for positioning purposes, preferably a tool steel.

[0053] For a uniform, dense and void-free coverage with the powder used in additive manufacturing, the edges of the workpiece holder are beveled in a preferred embodiment, presenting the overall shape of a truncated pyramid. The tapering shape towards the top, i.e. from the base plate upwards, results in a dense powder coverage. In addition, the correspondingly selected side angle provides the advantage that powder can migrate upwards between adjacent workpiece holders or between the workpiece holder and the build cylinder in case of dimensional changes as a result of temperature changes, more particularly expansion.

[0054] One problem with the upwardly tapered shape of the workpiece holders is that they cannot be gripped by normal gripping tools because they cannot hold on to the side walls or engage underneath the workpiece holders. A preferred solution to this problem is to provide gripping grooves in the side walls with vertical or, preferably, slightly undercut side walls (dovetail grooves). In such grooves, gripping tools find a sufficient hold, especially in embodiments with undercut side walls that allow a positive interlock.

[0055] The invention according to the aforementioned aspects will be further explained with reference to preferred exemplary embodiments and drawings. [Brief description of the drawings]

[0056] [Figure 1] FIG. 1 illustrates an isometric view of a build cylinder of an additive manufacturing system with a workpiece holder. [Diagram 2] FIG. 2 is an isometric view of a base support for the manufacturing system according to FIG. 1. [Figure 3a] FIG. 2 is a bottom isometric view of one embodiment of the workpiece holder of FIG. 1. [Figure 3b] 2 is a bottom isometric view of another embodiment of the workpiece holder of FIG. 1. FIG. [Figure 3c] 2 is a bottom isometric view of yet another embodiment of the workpiece holder of FIG. 1. FIG. [Figure 4] FIG. 2 is a top view of a workpiece holder of the first embodiment of the support system. [Diagram 5] FIG. 5 is a three-dimensional view of the “unfolded” workpiece holder according to FIG. [Figure 6] FIG. 6 is a cross-sectional view of the workpiece holder according to FIG. 5 placed on a base plate. [Figure 7] FIG. 3c shows a cross-sectional view of the workpiece holder according to FIG. 3c with a second embodiment of the positioning device. [Figure 8] FIG. 3c is an isometric view from below of the workpiece holder according to FIG. 3c with a third embodiment of the positioning device; [Figure 9] 9 shows an enlarged view of the workpiece holder on the base plate and a partial cross-sectional view of the positioning device according to FIG. 8. [Figure 10] 5 is a cross-sectional view of the workpiece holder according to FIG. 4 placed on a base support having locating pins, the locating pins being shown in cross-section and not in cross-section; [Figure 11] FIG. 1 illustrates an embodiment of a method for fabricating a workpiece according to an additive manufacturing process. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0057] 1 shows a schematic diagram of a build cylinder 2 of a machine for additive manufacturing with a build platform 4, which is vertically movable therein. Here, in particular the laser melting method is considered, in which the build platform is coated layer by layer with a powder of a build material and after each newly applied layer the structure of the workpiece is created by melting the powder by means of a laser.

[0058] The build platform 4 comprises a base support or base plate 6 (not visible here, see FIG. 2) on which workpiece holders 8 or pallets 8 are placed, optimally so that the entire surface of the base support 6 is covered as shown. As the guideline is that one workpiece is produced per pallet, different sizes of pallets 8 are used to suit the size of the workpieces to be produced, but this does not exclude the existence of unused pallets or the production of multiple workpieces on one pallet. Together with the pallets 8, the base support 6 forms a support system.

[0059] The base support 6 has pins 10 for the purpose of positioning the pallets 8. The pallets 8 have on their lower side 12 recesses 14 that are complementary in cross section to the pins 10 at least in the circumferential line, so that the pins 10 slide into the recesses 14 with little, if any, resistance, but in any case with only little or practically no play, thus keeping the pallet 8 in place with precision. The terms "recess" and "recess" are used synonymously in this specification and have the same meaning within the scope of this disclosure. For the smallest pallets 16, which have only one recess 14, it is advantageous or even necessary for automatic positioning on the base support 6 to provide a rotational restraint. In this case, the rotational restraint consists of a smaller rotational restraint recess 18 and a matching rotational restraint pin 20 on the base support 6.

[0060] Also, as will be explained further below, the rotational restraining means may generally be provided in the form of an off-center shaped raised portion relative to the pin 10 and a corresponding recess in the underside of the pallet 8. An alternative to this is a pin 10 having a shape that is not circularly symmetric, for example an oval, elliptical or polygonal cross-section, or other characteristic shapes that deviate from a circularly symmetric cross-section, such as a radially protruding nose, or a combination of the aforementioned shapes.

[0061] The pallet 8 according to an exemplary embodiment of the invention exhibits, at least on the upper side 11, a material on which the workpieces can be produced by an additive manufacturing process. It is therefore a material that is compatible with the respective building material. In the case of producing workpieces from metal powder, such a material is for example an aluminum alloy.

[0062] Another problem in this respect is that the manufacturing process is accompanied by an increase in temperature. For example, the base support 6 is heated, for example, to a temperature of 200° C. Furthermore, the melting of the building material, especially in the initial stages, is accompanied by an additional energy input near the surface 11, resulting in local temperature increases. These increases in temperature cause thermal expansion effects. Nevertheless, at least the surface of the pallet has to meet high requirements regarding dimensional stability. Apart from dimensional changes in the xy plane, i.e. parallel to the upper side 11 (see FIG. 1), curvatures due to temperature fluctuations, i.e. deviations from an exact plane, and displacements in the xy plane due to the occurrence of play around the pins 10 must be avoided or at least reduced to tolerable limits.

[0063] The xy-displacements are reduced in that the recesses 14, at least in the areas crucial for positioning, are made of a material with a correspondingly low thermal expansion. Tool steels are preferred for this purpose, and also heat-resistant tool steels, in particular with a view to the subsequent transfer of the pallet 8 to a machine tool for cutting production or to a machine tool for further thermal post-treatment at high temperatures, e.g. hot isostatic pressing.

[0064] Figures 4 to 6 show a first embodiment of a workpiece holder 8 (pallet 8) provided in the form of a sandwich-like structure, the pallet 8 being composed of an upper part 57 (herein also "upper element 57") and a lower part 59 (herein also "lower element 59"). The upper part 57 is composed of a material required for additive manufacturing, i.e. of a material on which the workpieces can be built from a building material using the respective additive manufacturing process. The lower part 59, on the other hand, is composed of a material with high strength and different, more particularly low, thermal expansion, as described below with respect to the sockets 28 and 42 of the second and third embodiment. The upper part 57 and the lower part 59 are connected to each other in a suitable manner. This is achieved, preferably in a detachable manner, for example by screws 61, which are preferably arranged symmetrically around the positioning recess 14, as shown. The screws 61 are screwed into corresponding blind holes 63 in the upper part 57.

[0065] It has been observed that this construction results in a smaller temperature gradient in the upper part 57 and a correspondingly lower tendency to form a curved surface. Another element counteracting the curvature can be the lower part 59, which is a rigid and temperature-stable element and therefore counteracts the formation of a concave curvature on the lower side of the upper part 57. In order to precisely position the lower part 59 and the upper part 57 relative to each other during their assembly, a first positioning bolt 65 of the lower part 59 is proposed, which can be inserted into a precisely fitting first positioning hole 67 of the upper part 57. Spaced apart from the positioning bolt 65, the lower part 59 comprises a second positioning bolt 69 intended to be inserted into a second positioning hole. The positioning hole has the feature of being elongated in the direction of the connecting line to the first positioning hole 67 and therefore presents an oval cross section or is provided in the form of an oblong hole. In this way, the different thermal expansion of the upper part 57 and the lower part 59 during heating of the pallet 8 is compensated without stressing the second positioning bolts 69. For larger pallets 8, it may be necessary to provide additional positioning bolts and holes offset laterally from the connection line between the first positioning bolt 65 and the second positioning bolt 69. In this case, a third positioning hole (not shown) must be provided for the second positioning bolt 69, with a larger cross section than the respective positioning bolt, to allow a displacement in any direction in the xy plane. Similarly, the holes 63 for the screws 61 in the lower part 59 are oversized in relation to the shanks of the screws 61, so that the screw heads of the screws 61 and their shanks can be displaced in the lower part 59 according to the relative thermal expansion of the upper part 57.

[0066] A workpiece holder 8 (pallet 8) according to a second embodiment of the support system is shown in FIG. 7. The body 9 of the pallet 8 is entirely made of a material suitable as a carrier material for additive manufacturing. The body 9 defines on its upper side the surface of the pallet 8, on which the workpieces can be built up. On the lower side of the body 9 a cylindrical recess 32 with an internal thread 26 is made. A socket 28 is made from tool steel substantially in the shape of a ring and is screwed onto the thread 26. The socket 28 has a rotation-restraining recess 30. In this case, two diametrically opposed rotation-restraining recesses 30 are provided in the socket 28, which serve to engage a screwdriver for screwing and unscrewing the socket 28.

[0067] The recess 32 receiving the socket 28 is limited by a relatively thin cylinder wall 36 surrounded by an expansion gap 38. If necessary, the cylinder wall 36, which also carries the internal thread 26, is undersized relative to the periphery of the socket 28 to compensate for the possible high thermal expansion, under manufacturing conditions, of the material of the body 9 of the lower element relative to the material of the socket 28. In particular, the undersized size is selected to ensure that the socket 28 is held without play on the thread 26 during additive manufacturing at the highest envisaged temperature.

[0068] It should be noted that with this solution, the socket 28 and, accordingly, the threads 26 of the pallet 8 must be made with high precision, since the socket 28 and the anti-rotation recesses 30 must be positioned with precision.

[0069] During processing, when large forces are applied to the pallet 8, the sockets 28 serve as engagement means for anchorages that are common in this process, such as pins with expandable balls or claws. The sockets 28 can also be removed during process steps that the sockets 28 would interfere with or cannot withstand, such as hot isostatic pressing.

[0070] In a third embodiment according to Fig. 8, the socket 42 is press-fitted into a recess 44 of the pallet 8. The socket 42 has a nose 46 in which a rotation-restraining recess 48 is located. Again, an expansion gap 50 is provided to reduce distortions that may occur due to the different thermal expansion coefficients of the body of the pallet 8 and the socket 42. The wall 52 into which the socket 42 is press-fitted is designed such that, even if the thermal expansion of the body of the pallet is greater than that of the socket 42, the wall 52 still holds the socket 42 at least without play at the highest occurring temperature.

[0071] As described in the second exemplary embodiment above, the socket 42 is made of heat-resistant tool steel and the body of the pallet 8 is made of a material suitable as a carrier material for additive manufacturing (e.g., aluminum or an aluminum alloy).

[0072] In this embodiment, the position of the rotation-reducing opening 48 is predetermined, but precise positioning in the vertical direction (z-direction) must be ensured while the socket 42 is pressed in. To ensure that this positioning is maintained even at the highest occurring temperatures, a higher prestress must be applied here, i.e., the wall 52 must be undersized relative to the socket 42, which exposes the material to higher loads.

[0073] Otherwise, the above description of socket 28 applies with regard to its fixing and removal during processing.

[0074] Fig. 10 shows a preferred embodiment of the pin 10. More precisely, Fig. 10 shows an embodiment in which the workpiece holder 8 is mounted on the base support 6 by means of the pin 10 and the associated recess 14. The workpiece holder 8 can be of one of the previously described embodiments, in particular the first embodiment according to Figs. 4 to 6. On the pin base 81 a pin cover 85 is fixed by means of screws 83. Between the pin base 81 and the pin cover 85 a ring 87 of a material having a higher thermal expansion (higher thermal expansion coefficient) than the lower element 59 (as shown) of the workpiece holder 8 of the first exemplary embodiment or the respective socket 28, 42 of the other embodiments is sandwiched. An aluminium alloy is preferred for this purpose. In particular, the ring 87 is arranged so as to lie precisely adjacent to the respective socket 28, 42 or, as shown, to an annular collar 91 of the lower element 59. When the pallet 8 is placed on the base support 6, the pins 10 slide easily into the pallet recesses 14 with as little play as possible. If the temperature increases, the ring 87 expands more than the surrounding material, thereby holding the pallet (workpiece holder) 8 on the base support 6 with increasing force.

[0075] As an alternative to the above-mentioned embodiment of the pin 10, a material with a higher thermal expansion may be provided at the edge of the hole. In particular, the holding portion 28, 42, 91 of the hole (14) may be made of a material with a higher thermal expansion coefficient than the material of the portion of the pin 10. In the first embodiment, this means that the collar 91 of the hole and possibly the entire lower element 59 are made of a material with a higher thermal expansion coefficient. In the second and third exemplary embodiments, this means that the socket 28 or the socket 42, respectively, are made of a material with a higher thermal expansion coefficient. According to this alternative, when the support system is heated, the surrounding hole 14 expands in a negative radial direction towards the pin 10, and the desired clamping effect is achieved.

[0076] The collar 91 is also similar to the sockets 28 and 42 and serves to engage the fastener during the next cutting process step. If the treatment is not favorable for the material of the lower part, for example due to excessive temperature, the lower part can be removed.

[0077] In particular, in additive manufacturing processes where powder is applied layer by layer in a planar manner, it should be avoided that voids or other irregularities are created in the layers. It must therefore be ensured that the space between the pallet 8 and the wall of the build cylinder 2 is filled uniformly with powder of the building material. Another effect is the thermal expansion or contraction, respectively, during the manufacturing process. When the pallet 8 expands, it must be ensured that the building material powder can move out of the space that decreases in size due to this process. On the other hand, if the size of the pallet decreases, it must be ensured that the powder can refill the increasing space, rather in a manner corresponding to the flow of a liquid, at least to ensure that no further displacements or movements occur in the powder after applying a layer of powder and smoothing it, i.e. the system is stable.

[0078] To meet these requirements, truncated pyramidal shaped pallets have been found suitable. The side walls of the pallets 8 in the exemplary embodiment are inclined so that the pallets taper from their lower side 12 towards their upper side 11. This results in a kind of funnel effect which, on the one hand, allows the powder to migrate when the spaces between the pallets or between the pallets and the cylinder wall decrease, and, on the other hand, ensures a safe and unresisted feed if the size of these spaces increases.

[0079] From another perspective, undercuts or cavities should be avoided for the reasons mentioned above. Specifically, this eliminates any gap between the lower side 12 of the pallet and the surface of the base support 6 for engaging a gripping tool under the pallet. Beveled side walls 95 make it more difficult to grip the pallet. For secure gripping, at least one side wall 95 is therefore provided with a gripping groove 97. That side wall 98 is vertical or preferably slightly undercut so that the gripping groove 97 is dovetailed and provides a hold for a suitable gripping tool. Because the dimensions of the gripping grooves 97 are relatively small, their orientation is nearly vertical, and there is limited undercutting to achieve the dovetail shape, the gripping grooves 97 do not pose any risk for irregular powder coating.

[0080] In particular, a particularity of the method using targeted melting of powdered material is that during removal of the workpiece, material is also removed from the surface of the build carrier. A further advantage of the first embodiment in this respect is that the upper part 57 can be easily replaced. In this regard, it is conceivable to make the upper part 57 smaller and to provide the gripping grooves 97 only in the lower part 59 from the tool steel. In this way, the shape of the upper part 57 is substantially simplified, i.e. a truncated pyramid with straight, continuous side walls.

[0081] In this regard, however, it is also conceivable to compensate for the loss of material of the pallet 8 in the upper part 57 in another way, for example by inserting an additive manufacturing step in which the material loss is compensated for by the growth of new material.

[0082] In the exemplary embodiments described above, the base support 6 includes at least one pin 10 and the workpiece holder 8 includes at least one hole 14. However, in alternative exemplary embodiments, the pin / hole pairs may be arranged in a reverse configuration, with the base support 6 having at least one hole and the workpiece holder 8 having at least one associated pin. In these exemplary embodiments, the clamping effect described above is also achieved in the manner described above. In the remaining aspects, these exemplary embodiments are similar to those described above. Furthermore, multiple pin / hole pairs may be provided, such that the base support 6 includes both a pin and a hole and the workpiece holder 8 includes an associated hole and pin.

[0083] In summary, the described pallet (workpiece holder) 8 together with the base support 6 provides a support system, which allows the workpieces to be transferred together with the pallet in a simple manner, in particular even by a robot, between the additive manufacturing system and a system for other treatments of the workpieces (cutting, heat treatment, cleaning, measuring). Overall, this offers considerable rationalization possibilities. Due to the appropriate construction of the pallet, adverse effects due to thermal expansion or the risk of irregular powder coatings were avoided. Thus, in a process, for example, the workpiece holder 8 can be transported in an automated manner from a system for additive manufacturing (e.g. a beam melting system for selective laser melting) to a system for subtractive treatment of the manufactured workpieces (more particularly from the base support 6 of the system). Optionally, in an intermediate step, the workpiece holder 8 together with the workpieces can be placed in a system for thermal post-treatment.

[0084] A method for manufacturing a workpiece using the support system of the first to third embodiments described herein can be carried out, for example, as follows: First, the workpiece holder 8 of the support system according to one of the embodiments is placed on the base support 6 of the support system of an additive manufacturing device. In this step, the pins 10 of the base support 6 engage with the holes 14 of the workpiece holder 8, as shown in FIG. 10 . Then, additive manufacturing of the workpiece is carried out by the manufacturing device on the workpiece holder 8. Due to the generated process heat, the temperature of the support system increases during the manufacturing process. Because the material of the portion 87 of the pin 10 has a higher thermal expansion coefficient than the material of the hole 14 of the workpiece holder 8 surrounding the portion 87, a clamping effect occurs between the pin 10 and the surrounding hole 14 due to the thermal expansion of the portion 87. Alternatively, the material of the retention portions 28, 42, 91 has a higher coefficient of thermal expansion than the material of at least the portion 87 of the pin 10, so that, alternatively, a clamping effect occurs between the pin 10 and the surrounding hole 14 due to the expansion of the retention portions 28, 42, 91.

[0085] After carrying out the additive manufacturing, the support system is cooled and the clamping action is released. The workpiece holder 8 together with the workpiece produced thereon is then removed from the base support 6 and transported to a system for subtractive post-processing of the workpiece. The workpiece holder 8 is placed on the support of the system for subtractive post-processing, the pins 10 of the support engaging in the holes 14 of the workpiece holder 8. Alternatively, the workpiece placed on the workpiece holder 8 may undergo one or more intermediate manufacturing steps between additive and subtractive manufacturing, for example a thermal post-processing step in a corresponding system, which also comprises a base support with corresponding pins, as in the systems for additive and subtractive manufacturing.

[0086] Examples include heat treatments for different materials suitable for additive manufacturing and corresponding pallet surfaces. - Aluminum alloys: Heat treatment in the range of about 200°C to about 500°C, preferably about 400°C to about 540°C - Titanium alloys: Heat treatment in the range of about 400°C to about 995°C (depending on the type of alloy), preferably about 480°C to about 730°C

[0087] Preferably, the pallet 8 and base support 6 are characterized by the following values: Inclination of the side walls 95: 1° to 11°, preferably 3° to 9°, 5° to 7° or about 6°. A large angle is especially associated with a significant reduction in the surface area available for production. A small angle is generally ineffective, associated with powder clogging. In particular, if the angle is too small, the powder is still trapped in the gap and can no longer escape upwards when the gap is reduced by thermal expansion. The height of the upper part 57 is between 1 / 4 and 3 / 4 of the total height of the pallet, however a maximum height of half the height of the pallet is preferred. The side walls 98 of the gripping groove 97 are each inclined at an angle of 10° to 40°, preferably 10° to 20°, more preferably 15° to 20°, with a preferred value of about 15°, relative to the bottom of the gripping groove 97. The depth of the gripping groove may be comprised between 3mm and 6mm, with a preferred value of 4mm. 1mm may be envisaged as the lowest limit. Pallet height: 25mm to 35mm. Hardness of the positioning parts (sockets 28, 42; lower part 59; and possibly also base support 6): from about 45 to about 68 HRC (Rockwell hardness C), preferably from about 50 to about 55 HRC.

[0088] From the foregoing description of exemplary embodiments, those skilled in the art will recognize modifications and additions without departing from the scope of the invention as defined by the claims. The base support 6 may in particular be provided with a peripheral edge which provides a transition between the build cylinder wall with rounded corners and the sharp corners of the pallet, thus saving build material which would otherwise have to be filled to fill the relatively large gaps which result between the side walls of the pallet and the build cylinder wall. In this context, detachable or non-detachable connections are conceivable. The provision of a rotation restraint may be omitted for pallets having at least two positioning means (recesses 14). The pallet 8 has, for example, more than one gripping groove 97 on more than one side, preferably on both sides, or more than one groove 97 on one side. Having more than one groove 97 on one side can be advantageous in the case of larger pallets. It is also conceivable to provide the corners of the pallet with gripping grooves, i.e. to provide at least one corner with a gripping groove. Instead of gripping grooves, reverse means are provided, i.e. ridges having a constant width or a width which decreases towards the pallet body. In the second positioning device, the slot 71 has a length that is up to 0.4 mm greater than its width and a hole with a larger diameter (an additional or alternative "third positioning hole" to the slot 71) has a diameter that is up to 0.4 mm greater than the first (positioning) hole 67.

[0089] In Fig. 11, a method for fabricating a workpiece in an additive manufacturing process is shown. The method can include additive manufacturing, for example, by one of the manufacturing apparatuses described herein. In particular, the method can include additive manufacturing of a workpiece on one of the workpiece holders 8 described herein (in particular, on the workpiece holder 8 according to the first embodiment).

[0090] The method according to Fig. 11 can be performed, for example, by a control device of an additive manufacturing apparatus. The method can also be provided by a central control device or a central computer, which controls both the additive manufacturing apparatus and the apparatus for subtractive post-processing. The control device and / or computer performing the method comprises a processor for performing the individual process steps and a memory in which program instructions for the individual process steps are stored.

[0091] According to a first step S1, the method comprises determining a position and / or orientation of a workpiece to be produced relative to a workpiece holder 8 on which said workpiece is additively manufactured, taking into account digital part data defining the geometry of the workpiece and taking into account conditions defined by subtractive post-processing of the workpiece. According to a second step S2, the method comprises performing additive manufacturing of the workpiece on the workpiece holder 8 based on the determined position and / or orientation of the workpiece.

[0092] Hereafter, further (partly optional) details of the method illustrated in FIG. 11 are described.

[0093] According to one embodiment, the manufacturing process of FIG. 1.) Importing parts from CAD 2.) Configuring additive manufacturing machines with palletizing / support systems 3.) Preparing the part for additive manufacturing (including step S1) 4.) Preparing the part for further removal procedures 5.) Generate the necessary machine control files (both adding and removing) 6.) Define quality assurance standards 7.) Start of all manufacturing processes (including step S2)

[0094] Regarding step 1. The method starts with the import of the digital part from the corresponding CAD (Computer Aided Design) program or from the connected PLM (Product Lifecycle Management) system, respectively. For this purpose, both native file formats, lightweight data and neutral exchange formats can be used. By way of example, we can mention formats such as *.prt, *.CATPart, *.step, *.igs, *.stl, JT, PVX, etc. Later, based on this geometry, the preparation for the additive construction process follows in step 3.) from the perspective of subtractive post-processing. This includes possible modifications of the existing CAD part based on the specific post-processing (e.g. oversize tolerances taking into account the implementation of the post-processing).

[0095] Regarding step 2. According to the geometric features of the CAD part or the part to be manufactured, the feasible build space of the additive manufacturing machine is configured. The size and material variations discussed with respect to the embodiment of the workpiece holder 8 and the base support 6 are available for selection. The configuration of the build space can be customized according to the requirements of the additive manufacturing in terms of gas flow, applicator direction, and scanning strategy. This configuration also includes considering an automated analog process chain using industrial robots for process optimization (e.g., the orientation of the gripping groove 97 mentioned above).

[0096] Regarding step 3. Preparing a part for additive manufacturing includes the steps of defining the part's position in the build space (following step S1) and corresponding pallet mounting, defining possible supports for additively manufacturing the part, and defining the exposure strategy and layer thicknesses of the additive manufacturing process.

[0097] a.) Position definition: The orientation of the part in the building space of the machine must be defined in terms of subtractive post-processing. This includes taking into account the subtractive process steps (e.g. countersinking, drilling, surface grinding, roughing, tapping, etc.), the tools required to perform these post-processing steps, the resulting constraints such as milling forces or torques, vibrations, etc., and the materials used. This information can be provided both manually and in an automated manner, based on internal strategies provided by the operator, databases, etc. In order to optimize the orientation of the workpiece in the building space, an analysis of the feasibility of achieving the machined area is performed based on the defined subtractive tools. This includes, among others, factors such as machine kinematics, tool geometry, tool interaction, etc. The quality of a particular orientation is visualized to the operator in the form of a false color representation. Furthermore, this representation can be combined with further quality criteria regarding part warpage, minimal complexity of the support geometry, additional building time, etc., and can be weighted individually.

[0098] b.) Supports: Based on the defined removal process steps, a calculation of a suitable support geometry is performed. The support geometry is designed in such a way that the resulting forces, torques, vibrations, etc. are absorbed and resisted accordingly. Weighting again follows with a view to minimizing the complexity of the support geometry. The applied strategies include simulation-based assessments based on topology optimization and machine learning processes based on evaluated previous manufacturing processes.

[0099] c.) Exposure strategies and layer thicknesses of the additive manufacturing process: The generation of the individual layers and the associated exposure strategies include defined subtractive process steps. This allows to locally adapt the resulting material properties of the additively manufactured workpiece in order to facilitate subtractive post-processing. The associated advantages are the gentle removal of the support material and the high-quality preparation of the quantities for precise post-processing.

[0100] Regarding step 4. The definition of the additive manufacturing steps is followed by the definition of the CAM (Computer Aided Manufacturing) paths according to known strategies. For this purpose, a selected orientation of the workpiece to be additively processed and a list of defined tools are referenced. The displacement paths obtained within the individual processing passes are checked for validity and generated as neutral G-code.

[0101] Regarding step 5. Based on the defined additive and subtractive process steps, a corresponding machine control file is generated. This includes both the generation of a build file for the corresponding additive manufacturing machine and the conversion of the neutral G-code into the format required by the specific subtractive processing machine or its control system, respectively. The definition of these steps is not limited to subtractive post-processing steps, but can be applied to tactile or optical measurement methods as well. This process step therefore allows both the definition of post-processing steps and the definition of automated quality assurance measurements.

[0102] Regarding step 6. In addition to the steps mentioned above, it is also possible to define further quality assurance criteria. This includes: a.) Definition of an unambiguous assignment of each part or pallet / workpiece holder to a specific manufacturing task, in the form of unambiguous identification by QR code, structural adaptation etc. b.) Collection and evaluation of process-relevant sensor data (analog, digital, optical, etc.) for additive manufacturing and the associated monitoring of the resulting part quality. c.) Definition of measurement points for the automated measurement of the additively manufactured blank, which is combined with a comparison to a digital target, resulting in a recalibration of the subtractive post-processing, if necessary.

[0103] Regarding step 7. Finally, the manufacturing begins and, according to step S2, an additive manufacturing process (e.g. selective beam melting) is first performed. For this purpose, predefined data is used. Then, optionally, a thermal post-treatment step and finally at least one subtractive post-treatment step of the workpiece follows. In an exemplary embodiment, the workpiece remains on the workpiece holder during the additive manufacturing and subtractive post-treatment. The workpiece holder can be one of the workpiece holders of the first to third embodiments described above.

[0104] The above-mentioned method according to Fig. 11 makes it possible to take advantage of the advantages of the support systems and their workpiece holders 8 according to the above-mentioned embodiments. This applies both to the digital preparation and to the analog process chain for the actual production. The entire process chain includes integration, coupling and monitoring in the sense of a Smart Factory. In the sense of a PLM (Product Lifecycle Management) solution, the lifecycle seamlessly represents the entire production process, starting from the digital part and ending at its safe disposal. This seamless integration allows production to be carried out without waste and without the risk of redundant steps, versions or interim solutions.

[0105] The method described above therefore reduces the administrative and operational effort, as well as the regulatory effort in the sense of validation according to guidelines, e.g. aviation or medical technology, in the entire integration chain.

Claims

1. 1. A support system for a manufacturing system, comprising: a base support (6) arranged to be mounted in a process chamber of the manufacturing system and comprising at least one positioning element; A workpiece holder (8) on which a workpiece can be produced according to a manufacturing process including layer-by-layer application of powdered raw materials; A support system comprising: the workpiece holder (8) has a lower side (12) and a build side as an upper side (11) of the workpiece holder (8) located substantially opposite the lower side (12); the workpiece holder (8) has at least one first positioning device on the lower side (12) for releasably and positionally accurate mounting of the workpiece holder (8) on the base support (6) of the support system, the at least one positioning element (10) and the at least one first positioning device (14) are designed in a complementary manner to form a pin / hole pair comprising a pin and a hole; At least one portion (87) of the pin is made from a first material having a first coefficient of thermal expansion and a holding portion (28, 42, 91) of the hole, which is crucial for the positioning accuracy, is made from a second material having a second coefficient of thermal expansion, the second coefficient of thermal expansion is smaller than the first coefficient of thermal expansion, so that when the temperature of the support system increases during the manufacturing process, a clamping effect occurs between the pin and the surrounding hole due to the expansion of the portion (87) of the pin, or A support system, wherein the first coefficient of thermal expansion is smaller than the second coefficient of thermal expansion, such that when the temperature of the support system increases during the manufacturing process, a clamping effect occurs between the pin and the surrounding hole due to expansion of the retention portion (28, 42, 91) of the hole.

2. A workpiece may be fabricated on said workpiece holder according to an additive manufacturing process including layer-by-layer application of powdered raw materials; the workpiece holder (8) has a lower side (12) and a build side as the upper side (11) of the workpiece holder (8) located substantially opposite the lower side (12), the workpiece support (8) has at least one first positioning device (14) on the lower side (12) for releasably and positionally accurate mounting of the workpiece support (8) to the base support (6) of the manufacturing apparatus; said workpiece holder (8) comprising a plate-shaped upper element (57) and a plate-shaped lower element (59); said upper element comprising said upper side (11) and said lower element comprising said lower side (59); 2. The workpiece holder (8) for a support system according to claim 1, wherein the upper element (57) is made from a different material than the lower element (59).

3. A workpiece may be fabricated on said workpiece holder according to an additive manufacturing process including layer-by-layer application of powdered raw materials; the workpiece holder (8) has a lower side (12) and a build side as the upper side (11) of the workpiece holder (8) located substantially opposite the lower side (12), the workpiece support (8) has at least one first positioning device (14) on the lower side (12) for releasably and positionally accurate mounting of the workpiece support (8) to the base support (6) of the manufacturing apparatus; The upper side (11), at least on its surface, is composed of a build carrier material that is compatible with a part build material of the additive manufacturing process, so that a workpiece can be additively fabricated from the build material on the workpiece holder (8) while being coupled to the surface of the upper side, and the workpiece holder (8) can be removed together with the workpiece from the base support (6). A workpiece holder (8) as described in claim 2 or a workpiece holder (8) for a support system as described in claim 1.

4. 4. A workpiece holder according to claim 2 or 3, wherein the lower element (59) and the upper element (57) are detachably connected to each other and, optionally, screwed to each other.

5. 5. A workpiece holder (8) according to claim 2, wherein starting from the upper side (11), at least ¼ of the height of the workpiece holder (8) forms the upper element (57), and starting from the lower side (12), the lower element (59) extends up to the upper element (57), and in the lower element (59) at least a part of the first positioning device (14) is provided in the form of a hole.

6. The second material is - Heat resistance up to 550°C, - Hardness ranging from 45 to 68 HRC (Rockwell Hardness C) 6. A workpiece holder (8) according to claim 2, which exhibits at least one of the following two characteristics:

7. 7. The workpiece holder (8) according to claim 2, wherein second positioning devices (67, 71, 65, 69) are provided on the upper element (57) and on the lower element (59) and have a complementary configuration to each other so that the upper element (57) and the lower element (59) can be positionally accurately fixed to each other, the second positioning devices (67, 71, 65, 69) comprising at least two pairs of holes (67, 71), including a first hole (67) and at least one second hole (71), the second holes being shaped as slots so that a positioning bolt (71) of the second positioning device inserted therein can be displaced in at least one direction to compensate for thermal dimensional changes of the upper element (57) relative to the lower element (59).

8. 8. A workpiece holder (8) according to any one of claims 2 to 7, wherein the first positioning device is substantially the hole (14), and the holding portion (28, 42, 91) of the hole represents a substantially annular portion of the inner wall of the hole and optionally comprises at least one ring (28, 42) per hole which is pressed or screwed into.

9. 9. The workpiece holder (8) according to claim 8, wherein the first positioning device is substantially the hole (14), and a second recess (18) having a circular cross-section and arranged offset relative to the hole (14) is provided in the workpiece holder (8), or the hole (14) has an elliptical, oval or polygonal cross-section, so that the workpiece holder (8) is prevented from rotating when placed on the base support (6) having the at least one positioning element (10) of a complementary configuration.

10. 10. A workpiece holder according to claim 8 or 9, wherein the lower element (59) is made from the second material.

11. 11. A workpiece holder (8) according to claim 2, wherein a side surface (95) of the workpiece holder (8) between the lower side (12) and the upper side (11) is inclined, so that the workpiece holder (8) narrows from the lower side (12) towards the upper side (11).

12. 12. A workpiece holder (8) according to any one of claims 2 to 11, wherein at least one of the sides of the workpiece holder (8) can be provided with at least one gripping means in the form of a groove or a ridge.

13. 13. A workpiece holder (8) according to claim 12, wherein the gripping means (97) are designed in the form of a groove having a dovetail cross section.

14. 14. The support system according to claim 1, wherein the workpiece holder (8) is designed according to any one of claims 2 to 13.

15. 15. An additive manufacturing apparatus using a manufacturing process including layer-by-layer application of powdered raw materials, the manufacturing apparatus comprising a build stage and a support system according to claim 1 or 14, the build stage of the manufacturing apparatus comprising the base support (6) of the support system.

16. 16. The manufacturing apparatus according to claim 15, wherein the base support (6) comprises an array of positioning elements, the array of positioning elements including the pins (10), at least one, preferably all, of the pins (10) having a circular cross-section and additionally at least one rotation-inhibiting pin (20) respectively, or having an elliptical, oval or polygonal cross-section such that rotation is inhibited when the workpiece holder (8) is placed on the base support (6).

17. placing the workpiece holder (8) of the support system according to claim 1 or 14 on the base support (6) of the support system of an additive manufacturing device, wherein the at least one positioning element (10) and the at least one positioning device (14) are designed in a complementary manner to form the pin / hole pair with the pin and the hole, the pin engaging with the hole; performing additive manufacturing of a workpiece on the workpiece holder (8) by means of the manufacturing device, the temperature of the support system increasing during the manufacturing process and causing a clamping effect between the pin and the surrounding hole due to the expansion of the portion of the pin (87) or due to the expansion of the holding portion of the hole (28, 42, 91); cooling the support system, whereby the clamping effect is relieved; disengaging the workpiece holder (8) together with the workpiece fabricated thereon from the base support (6); placing the workpiece holder (8) on a support of an apparatus for ablation post-processing of the workpieces, whereby positioning elements (10) of the support and the positioning devices (14) of the workpiece holder (8) engage with each other; A method for fabricating a workpiece comprising:

18. Prior to the step of placing the workpiece holder (8) on the support of the equipment for subtractive post-treatment, 18. The method according to claim 17, further comprising the step of placing the workpiece holder (8) on a support of an installation for thermal post-treatment of the workpiece.

19. The step of disengaging further comprises:

19. A method according to claim 17 or 18, comprising gripping the workpiece holder (8) by a gripping tool at the gripping means (97) arranged on the side of the workpiece holder (8).

20. 20. The method according to any one of claims 17 to 19, wherein a plurality of workpiece holders (8) are arranged side-by-side on the base support (6) of the manufacturing apparatus.

21. 1. A method for fabricating a workpiece according to an additive manufacturing process, comprising: determining a position and / or orientation of a workpiece to be produced relative to a workpiece holder (8) on which said workpiece is additively manufactured, taking into account digital part data defining the geometry of said workpiece and taking into account conditions defined by a subtractive post-processing step of said workpiece; performing additive manufacturing of the workpiece on the workpiece holder (8) based on the determined position and / or orientation of the workpiece; A method comprising:

22. determining a support geometry including at least one support structure for the workpiece taking into account the conditions defined by the subtractive post-processing of the workpiece; 22. The method of claim 21 , wherein the step of performing additive manufacturing comprises additive manufacturing of the support structure.

23. 23. The method of claim 21 or 22, wherein the conditions defined by the subtractive post-processing of the workpiece include at least one of the following conditions: milling force of a tool used in the subtractive post-processing, milling torque of the tool used in the subtractive post-processing, vibration during the subtractive post-processing, possibility of achieving the geometry of the workpiece and / or the support structure by the tool used in the subtractive post-processing, machine kinematics of the tool used in the subtractive post-processing, tool geometry of the tool used in the subtractive post-processing, tool coordination of the tool used in the subtractive post-processing.

24. 24. The method of any one of claims 21 to 23, further comprising configuring an available build space of a manufacturing apparatus for the additive manufacturing of the workpiece.

25. 25. The method of any one of claims 17 to 24, further comprising determining layer thicknesses of the additive manufacturing and / or determining an exposure strategy for the additive manufacturing taking into account the digital part data defining a geometry of the workpiece and taking into account the conditions defined by the subtractive post-processing of the workpiece.

26. 26. The method according to any one of claims 21 to 25, further comprising the step of providing a support system according to claim 1, and wherein the workpiece holder (8) is the workpiece holder (8) of the support system.

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