Additive manufacturing device with decoupled process chamber and additive manufacturing method

Abstract

The present invention relates to a manufacturing facility based on optical interaction, more particularly a manufacturing facility for selective laser melting. Particularly high accuracy during part manufacturing can be achieved easily by means of a special arrangement of the main components of the device, such as the process chamber (1) and optical module (9), in relation to one another and through decoupled mounting and provision of positioning elements.

Description

[0001] Additive manufacturing device with decoupled process chamber and additive manufacturing process

[0002] The present invention relates to an automatable manufacturing system based on optical interaction, in particular a manufacturing system for selective laser melting (SLM) with an optimized arrangement of the accuracy-determining components so that external interference and interference occurring during the process can be minimized. Furthermore, an optimized additive manufacturing process is proposed.

[0003] SLM systems known from the prior art are designed in such a way that the individual elements required to produce an SLM component, such as in particular the optics module, a build chamber, a coater and the Z-axis, are attached directly to the build chamber or directly to one another and to each other.

[0004] However, this type of bonding has the disadvantage that changes in the relative position and / or orientation of the elements or subcomponents in this composite, particularly due to thermal deformation or the application of force, result in unwanted changes in the overall structure. This leads to deviations and inaccuracies in the manufacturing of the component. The deformation of the structures of the main components typically causes point positioning errors in the position and orientation of the laser beam in the powder plane, which are either not reproducible or compensable, or can only be compensated with considerable effort.

[0005] Particularly in the case of SLM machines with multiple laser scanning systems, deviations in the relative positions of the various laser beams in the powder plane can occur. Furthermore, deviations in the powder bed surface, such as the position or orientation, as well as the actual layer thickness, can occur. This can compromise the quality of the manufactured component, leading to geometric errors such as shape and position deviations, reduced surface quality, or metallurgical defects such as bonding defects or gas porosity.

[0006] A device for producing molded bodies based on the principle of selective laser melting is known, for example, from DE 10 2019 200 680 A1. The subject matter of this application is hereby incorporated by reference.

[0007] An object of the present invention is to provide a manufacturing device for additive manufacturing with which improved manufacturing quality of the component to be manufactured can be achieved. Furthermore, an object of the invention is to provide an optimized manufacturing method with which improved manufacturing quality can be achieved. In particular, an object of the invention is to minimize the disruptive factors and influences occurring during the production of an SLM component, in particular thermal influences and force influences, so that the quality of the object to be manufactured can be improved.

[0008] To solve these problems, the features of the independent claims are proposed. Advantageous embodiments can be found in the dependent claims.

[0009] A device for the layer-by-layer construction of objects from powdered material using optical interaction may comprise a process chamber and at least one optical module. The device may, in particular, utilize a selective laser melting process.

[0010] The process chamber can be provided to provide a work space on a construction site. At least one optics module can be provided, which is part of an irradiation device or which forms an irradiation device for the location-selective irradiation of the material present in the region of the construction site. The optics module is preferably arranged above the process chamber and spaced apart from it. A primary carrier or a receiving element can enable central connection of individual main components of the device. The receiving element or base element functions as a carrier device for receiving or storing the main components of the device or production system. Main components include in particular those components of the device that are necessary for producing the object, i.e. in particular one or more optics modules, the process chamber, a coater and a Z-axis and / or lifting device.Advantageously, the at least one optical module is mounted or accommodated on the base element at a first connection point. Further advantageously, the process chamber is decoupled from the at least one optical module and accommodated or mounted on the base element at a spaced-apart second connection point. Thus, the optical module is arranged separately from the process chamber, with both the optical module and the process chamber being mounted on the base element.

[0011] Thermal expansion of the process chamber thus no longer directly affects the spaced-apart optics module. Since all main components of the device are preferably arranged separately and spaced from one another on the base element, thermal and mechanical interference between the main components is also minimized.

[0012] Preferably, the main components are mounted exclusively on the base element, with the main components particularly preferably being mounted only at one or more connection points, which are provided separately for each of the main components. The main components or accuracy-determining components are therefore arranged in such a way that they do not influence each other or that the influence is kept as minimal as possible.

[0013] Particularly preferably, the process chamber is mounted on the base element via a plurality of connection points, wherein each of the connection points is spaced from the first connection point (at which the optical module is mounted) and wherein particularly preferably the plurality of connection points are arranged substantially in a horizontal plane.

[0014] Particularly preferably, the basic element has a reference plane, relative to which the main components are arranged and positioned and whose relative position is used as position information, for example to compensate for deformations.

[0015] In other words, all relevant components are preferably connected to the base element and a plane of the device, which is defined as a common reference plane and which is particularly preferably the reference plane of the optical module, is used as a reference plane for each of the individual main components.

[0016] This characteristic arrangement of the main components, and in particular the optics module and the process chamber, spaced and separated from each other directly on the base element so that the thermal and mechanical influence of these components can be minimized, can significantly improve the manufacturing quality of the device.

[0017] The individual main components of the device, such as the process chamber, the optics module, a lifting device, and a construction cylinder, can be mounted separately from one another and preferably directly on the base element. The mounting is preferably designed in such a way that thermal expansion of the individual components is enabled without introducing significant forces into the base element, so that deformation of the main components is freely possible within predetermined tolerance ranges without introducing forces or deformations into the other main components or the base element. For example, the support points of the main components can be reduced so that they are each mounted on a separate bearing point on the base element, so that the body of the connected main component introduces no or only minimal forces into the base element in the event of thermal deformation.Furthermore, it is possible to design the bearing points of the mounted main components in such a way that a certain amount of play is provided, particularly in the vertical direction, so that no forces are introduced into the base element in the event of thermal expansion in the vertical direction of the connected main component. In particular, the separate arrangement of the individual main components on the same base element can minimize the mutual thermal and mechanical influences between the main components, thus improving the quality of the component to be manufactured.

[0018] At least one of the main components, such as the process chamber, the optics module, the lifting device, and / or the construction cylinder, can be mounted on the base element in a thermally decoupled manner. Thermally decoupled mounting on the base element can be achieved, for example, by using components made of thermally insulating materials. In particular, thermally insulating plates and disks, for example made of ceramic, glass, or fiber-reinforced plastics, can be used as intermediate elements at the bearing points or connection points. In addition, spacer plates made of thermally insulating plastic can be used. This advantageous design allows the thermal influence on the base element to be further reduced. The influence of the main components on one another can also be significantly reduced.In particular, the thermal deformation of the process chamber is essential, so that particularly preferably at least the process chamber is mounted via thermally insulating materials, such as ceramic plates or plastic discs at (preferably each) of the at least one bearing point or connection point.

[0019] A cooling device for cooling the connection point can also be provided at the second connection point. The second connection point is the (one or more) connection points between the process chamber and the base element, which is separate from the first connection point. For example, cooling channels can be provided in bearing plates or support plates, which enable active cooling or temperature control of the second connection point (or second connection points) and thereby minimize or actively influence the thermal influence of the process chamber on the base element and the other main components. Passive cooling is also possible, so that, for example, cooling fins can be provided to cool the second connection point (or second connection points), thus contributing to reducing the thermal influence of the process chamber on the base element.

[0020] Preferably, the main components of the device can be thermally and mechanically decoupled from the process chamber. In particular, the main components of the device can be provided on the base element, separate from the process chamber. In particular, one or more adapter elements for gas-tight and / or laser-safe shielding from the environment can also be provided between the optics module and the process chamber. The adapter element is preferably arranged above the process chamber and below the optics module. Since an adapter element is provided as an intermediate element between the optics module and the process chamber and the adapter element can be designed to be particularly flexible and enables gas-tight shielding of the transmission area from the optics module to the process chamber, a flexible connection can be achieved, as well as thermal and mechanical decoupling of the optics module from the process chamber.Preferably, the adapter element is connected directly to the optics module and directly to the process chamber. Thus, even strong heating of the process chamber does not affect the optics module. Advantageously, the adapter element is connected to the process chamber in such a way that relative movement between the process chamber and adapter element is permitted in both a horizontal and a vertical plane. For this purpose, sealing rings and / or membranes can be provided at the connection point. By using a movable bearing (preferably in both a horizontal and vertical direction) combined with sealing rings and / or membranes, relative movement of the connected process chamber can be enabled. Deformations of the process chamber are thus not transmitted to the optics module via the adapter element, but are compensated for in a gas-tight and / or laser-safe manner by the specific connection of the adapter element.The mutual thermal and mechanical influences between the components can be minimized, so that the manufacturing quality of the component can be significantly improved.

[0021] Particularly advantageously, the adapter element is designed to be flexible, allowing a relative movement of the process chamber to the optics module free of mechanical stresses. For this purpose, the adapter element can, for example, have a telescopic structure and / or be constructed of flexible materials. In particular, the adapter element comprises at least one membrane and / or at least one sealing ring to enable mechanical and thermal decoupling from the process chamber and / or the optics module.

[0022] Particularly preferably, the adapter element has an integrated protective glass to protect the optics module from the particle-contaminated process atmosphere of the process chamber. Particularly preferably, the protective glass is rigidly connected to the optics module to prevent relative displacement of the protective glass to the optics module and thereby ensure precision during component manufacturing. Particularly preferably, the adapter element is provided between the optics module and the process chamber and in connection with the optics module and the process chamber.

[0023] The individual main components can have a common reference plane. The individual main components can be aligned to one another via the common reference plane, in particular by means of positioning elements made of temperature-invariant material. A temperature-invariant material is, for example, Invar or fiber-reinforced plastics, such as carbon fiber-reinforced or glass fiber-reinforced plastics. For example, ceramic or glass can also be used. Because all individual main components have a common reference plane, the position, displacement, and orientation of the main components can be determined with respect to a common reference plane, thus enabling precise position and orientation determination of the main components. For example, compensation for displacements relative to the reference plane can be achieved via the machine control system and thus by adjusting the beam path.To enable the most precise determination of the position and orientation of the main components, the relative position of the individual main components to the common reference plane can also be determined relative to the intended positioning elements of the respective main components. Since the positioning elements are made of temperature-invariant material and are directly connected to the common reference plane, the positioning elements behave essentially temperature-invariantly. Thus, the individual positioning elements provide reference points or a reference scale for the metrological determination of the position and orientation of the individual main components. Thus, a displacement or the orientation of the main components can be determined simply and reliably by determining the relative position and orientation with respect to the positioning element.Preferably, the positioning elements extend from the common reference plane on the top side of the base element vertically downwards into the device, to the process chamber and to the lifting device and / or the construction cylinder.

[0024] At least one of the main components can advantageously be coupled to the common reference plane by means of a positioning element for determining deviations in the orientation or positioning of the respective component. The positioning element can advantageously be provided directly on the common reference plane and extend to the respective main component. The connection point between the main component and the positioning element can be used to metrologically determine changes in the position and orientation of the main components. This advantageously allows for a precise determination of the position and orientation of the main component relative to the common reference plane.

[0025] The displacement of the main components can be recorded electronically using measuring equipment and directly and / or simultaneously processed in the machine control system. This allows the detected displacement, particularly the adjustment of the optical module's beam path, to be compensated for, thereby improving the component's manufacturing quality.

[0026] The individual main components can be directly mechanically connected to the common reference plane via positioning elements, at least in part, to establish a constant distance from the common reference plane. This further development makes it possible, for example, to fix or position floating-mounted main components using positioning elements made of thermally invariant material, so that, for example, a constant distance can always be achieved in the vertical direction between the common reference plane and the connection point between the positioning element and the main component. The floating support, in turn, allows the main component to be expanded, while the connection point to the positioning element remains as a fixed point.The connection point to the positioning element is selected in particular in such a way that a displacement of the main component has the least possible impact on the component quality of the component to be manufactured.

[0027] The common reference plane can advantageously be the reference plane of the optics module. This particularly advantageous definition of the reference plane enables simple and efficient position and orientation determination of the main components and precise compensation. Particularly advantageously, the base element is designed in such a way that it forms a frame that encloses the process chamber (in particular completely). This enables particularly advantageous mounting of the main components, and in particular the process chamber, on the base element. Furthermore, thermal expansion of the base element can be compensated for, at least up to a predeterminable maximum value.

[0028] Advantageously, the device can have at least one coater for preparing the powdered material. The coater can comprise an alignment device. To ensure constant position and orientation of the alignment device, it can be connected directly to the reference plane by positioning elements, particularly preferably mechanically. The positioning elements can be designed as rods, bars, or thin beams made of temperature-invariant material (as already described). This particularly advantageous design makes it possible to keep the distance between the alignment device and the common reference plane essentially constant and thus essentially independent of thermal expansion. Thus, high component accuracy can be achieved in a particularly efficient manner.Preferably, the positioning elements are oriented along the Z-axis so that a change in length along the Z-axis is prevented as far as possible.

[0029] Advantageously, the device can comprise a Z-axis measuring system. To maintain the constant position and orientation of the measuring system, the measuring system can be directly connected to (or mounted on) the reference plane by positioning elements. The measuring system can also be provided as a measuring system for the lifting device.

[0030] Advantageously, process monitoring systems, such as a camera system, a powder bed monitoring system, and / or a melting point monitoring system, can be provided, each of which is coupled to the common reference plane (preferably directly connected to the reference plane). These additional process monitoring systems are thus advantageously arranged independently of the process chamber and connected or mounted directly on the base element.

[0031] Advantageously, a method for producing objects using a device as mentioned above is proposed, wherein the method may include the step of determining the position and / or orientation of at least one main component relative to a common reference plane using at least one positioning element. Thus, particularly precise production of the object can be achieved.

[0032] In addition, the method can include the step of compensating for displacements detected directly or simultaneously by the machine control system by adjusting the beam path (particularly of the optics module). This allows for particularly precise production of the object.

[0033] The method may further comprise the step of determining the position and / or orientation of the main components, using the individual main components and the associated positioning elements as a reference. As already described, the positioning elements made of thermally invariant material are to be regarded as fixed points relative to the common reference plane and thus enable simple and straightforward detection of the position and orientation of the respective main component by determining the relative distance (or change in distance) of the main component to the respective positioning element.

[0034] In a further advantageous embodiment, the process chamber can be released at the connection point to the base element along a release direction, in particular in the vertical direction, and wherein a coupling element can additionally be provided, in particular a coupling rod, which couples the movement along the release direction to a reference plane. The coupling rod can be designed as a positioning element and thus consist of temperature-invariant material. The positioning elements can also be designed as rods that are attached directly to the common reference plane. The device can also have a lifting device for vertically positioning a build plate. In addition, a build cylinder can be provided for guiding the build plate. Both the lifting device and the build cylinder can be mounted directly on the base element.All main components can be spaced apart and independent of the process chamber, in particular on the base element.

[0035] Advantageously, the individual main components can be connected to the base element in a decoupled manner, and the main components can be aligned with each other via a common reference plane. The process chamber can advantageously be mounted separately and independently of the optics module on the base element. The process chamber can be a process chamber housing to provide a workspace sealed from the environment during the construction process.

[0036] Short description of the characters

[0037] Fig. 1: shows a cross-sectional view of an additive manufacturing system;

[0038] Fig. 2: shows the layout of the coater of the additive manufacturing system;

[0039] Fig. 3: shows another side view of the production plant during thermal expansion;

[0040] Fig. 4: shows another side view of the system with the positioning element installed;

[0041] Fig. 5a and 5b: shows another production facility.

[0042] Detailed description of preferred embodiments

[0043] In the following, exemplary embodiments of the present invention are described in detail with reference to exemplary figures. The features of the exemplary embodiments can be combined in whole or in part, and the present invention is not limited to the described exemplary embodiments.

[0044] Fig. 1 shows a schematic embodiment of a manufacturing plant based on optical interactions, specifically a manufacturing plant for selective laser melting (SLM plant), in which a powder material to be processed is applied layer by layer on a movable base plate and locally remelted by means of focused laser irradiation in such a way that a three-dimensional workpiece (object to be manufactured) can be generated by continuously applying, exposing and fusing further material layers (additive manufacturing).

[0045] For this purpose, the production system provides at least one laser light source, which generates a light beam via a control system coupled to the production system. This light beam is focused onto the material layer to be processed via a light path using various optical elements integrated into a scanning head, such as focus or scattering lenses, mirrors, optical filters, etc. The production system has an optics module 9 for guiding the light beam.

[0046] The problem with conventional SLM machines is that the main components, such as the optics module, the build chamber (or process chamber), the coater, as well as the lifting device or the Z-axis, are usually directly or at least partially connected to the build chamber or process chamber or are directly attached to it. This has the disadvantage that changes in the relative position and / or orientation of the elements, for example due to thermal expansion or mechanical deformation, result in unwanted changes in the overall system that distort the manufacturing process and thus lead to manufacturing errors, which are particularly attributable to point positioning errors in the position and orientation of the laser beam in the powder plane. Due to the interaction of the thermal deformation of the main components, which are at least partially directly connected to one another, compensation is only possible with great effort.

[0047] In contrast, the present invention proposes a decoupling of the main components. As shown, for example, in Fig. 1, the optics module 9 is mounted directly at a first connection point 0 on the base element 3. Separately and spaced from this, the process chamber 1 is mounted directly on the base element 3 at a second connection point 13.

[0048] For the connection, particularly to the process chamber 1, thermally insulating materials are preferably used, for example, ceramic or plastic discs or insulating plates as intermediate elements of the bearing surfaces. The second connection point 13 is the connection point for connecting the base element 3 to the process chamber 1, which therefore preferably enables thermally insulating mounting. This enables thermal decoupling of the process chamber 1, which heats up to, for example, 50°C to 80°C during operation of the system.

[0049] Figure 1 shows a single connection point (or bearing point) for the second connection point 13, whereby the process chamber 1 can preferably also be mounted on the base element 3 via a plurality of second connection points (preferably via four connection points). These second connection points can be arranged substantially in a horizontal plane, and the process chamber 1 can be placed (preferably exclusively) on the underside and firmly connected thereto. The first connection point (at which the optics module 9 is mounted) is preferably arranged at a distance (vertically and / or horizontally) from each of the second connection points.

[0050] Preferably, the base element 3 has a common reference plane 2, relative to which the main components are arranged and positioned, and whose relative position is used as position information, for example, to compensate for deformations. In an advantageous embodiment, the optics module 9 is mounted directly on this common reference plane 2 (for example, directly on the top side of the base element 3).

[0051] In addition, one or more positioning elements are provided, which extend vertically downwards, for example, toward the main components. Positioning elements include, for example, positioning elements 4 or 8. These are designed such that they are thermally and mechanically decoupled from the main components, and in particular from the process chamber 1, while simultaneously being attached to the common reference plane 2. For example, the positioning element 4 can be suspended in the process chamber 1 or arranged laterally to enable efficient determination of the orientation and position of the process chamber 1 relative to the common reference plane 2. Advantageously, the positioning element 4 is not directly connected to the process chamber, but functions merely as a distance scale or relative point for measuring the relative distances.The main components can be considered to be in particular the process chamber 1, the optics module 9, the lifting device 10 and / or the construction cylinder 11.

[0052] In addition, to further improve accuracy should thermal displacements nevertheless occur, these displacements can be determined electronically using measuring instruments and directly and preferably simultaneously calculated in the machine control system. Additional process monitoring systems 12 can therefore also be provided. These process monitoring systems 12 can preferably be directly connected to the common reference plane and / or fixed thereto. Advantageously, camera systems for monitoring the device, as well as powder bed monitoring systems for monitoring the powder bed and melting point monitoring systems can be provided, which in turn are directly coupled to the common reference plane 2, so that they are not subject to thermal and mechanical displacements and provide precise and unadulterated data.

[0053] An adapter element 14 is advantageously provided between the optics module 9 and the process chamber 1. This adapter element 14 can be used to create a gas- and laser-tight shield from the environment, ensuring optimal transmission of the laser beam from the optics module 9 into the process chamber 1. The adapter element 14 is designed or connected in a flexible manner, allowing relative displacements of the process chamber 1 to the optics module 9 without the transmission of mechanical stresses. The relative movement while maintaining tightness can be achieved using membranes or sealing rings.

[0054] The adapter element 14 is connected to the process chamber 1 at a connection point in such a way that relative movement between the process chamber 1 and the adapter element 14 is permitted in both a horizontal and a vertical plane. For this purpose, several sealing rings and / or membranes can be provided at the connection point. By using a movable bearing (preferably in both a horizontal and a vertical direction) combined with sealing rings and / or membranes, relative movement of the connected process chamber 1 can be permitted while simultaneously ensuring tightness. Deformations of the process chamber 1 are thus not transmitted to the optics module 9 by the adapter element 14, but are compensated for in a gas-tight and / or laser-safe manner by the specific connection of the adapter element 14.The mutual thermal and mechanical influences between the components can be minimized, so that the manufacturing quality of the component can be significantly improved.

[0055] Furthermore, a protective glass can be integrated into the adapter element 14 to protect the optics module from the particle-contaminated process atmosphere in the process chamber 1. However, the protective glass must be rigidly connected to the optics module 9 to prevent relative displacement of the protective glass relative to the optics module.

[0056] Fig. 1 also shows a measuring system 6, which can be used to measure the Z-axis 7 and uses a positioning element 8 as a reference. The measuring system 6 can also be used to determine the position and orientation of main components, for example the construction cylinder 11 and the process chamber 1. The measuring system and preferably all measuring systems of the device are referenced to the common reference plane 2, in particular via positioning elements. By using the positioning element 8 as a reference element, a precise position and orientation determination of the main components can be achieved. The positioning element is made of temperature-invariant material. A temperature-invariant material is, for example, Invar or fiber-reinforced plastics, such as carbon fiber-reinforced or glass fiber-reinforced plastics.

[0057] Located in the build cylinder 11 is the lifting device 10, which is vertically movable, for example, to raise or lower a base plate relative to the circumferential transformation. At the beginning of a build process, a layer of material powder is deposited and leveled on the plate using an alignment device (or a coater 22). During the build process, after successive application of the layers and fusion of the desired sections, the lifting device 10 is gradually lowered to allow a new layer of material powder to be applied to the build area.

[0058] As shown in Fig. 1, an additional measuring device 5 is also provided, which can detect the relative position of the lifting device 10. Displacements are determined here, for example, in the vertical direction. In parallel, positioning elements 8 can be provided laterally to the measuring device 5 to determine the relative positioning of the individual main components and the position or zero point of the measuring system 5. The positioning elements 8 are preferably connected directly to the common reference plane 2. Since the positioning elements are made of thermally invariant material, they do not essentially change shape due to thermal influences, but remain constant in length. The distance of the positioning elements from the common reference plane 2 can therefore be regarded as essentially constant. The measuring device 5 is provided for determining the position and orientation of the construction platform of the lifting device 10.For this purpose, the measuring device 5 can be located, for example, in or parallel to the lifting device 10. Furthermore, the measuring device 5 can have a positioning element arranged within the cylinder of the lifting device 10 to provide a constant reference for determining the position. Laser distance sensors, in particular, can be used as the measuring device 5, or tactile measuring devices such as a touch sensor can be used.

[0059] Each of the positioning elements provides fixed points relative to the common reference plane, which are used to easily determine the displacement and / or orientation change of the individual main components. Similar to a ruler or a fixed scale fixed to the common reference plane 2, it is therefore possible to determine a displacement relative to the common reference plane 2 by measuring or determining the relative position change between a main component and the positioning element. The determined displacement can be used via the machine control system to compensate for the beam path in order to achieve the highest possible component accuracy during workpiece production.

[0060] As shown in Fig. 1, two positioning elements 8 are arranged laterally and at a distance from the process chamber 1, wherein these positioning elements can be used, for example, to determine the position of the lifting device 10 and / or the cylinder 11, but also to determine the position of the process chamber 1. By providing two spaced and parallel positioning elements 8, the position of main components on two different sides can be determined, so that a change in position and also a change in orientation can be determined easily and precisely.

[0061] The process chamber 1 is firmly connected to the base element 3 at the second connection point 13. However, as can be seen from Fig. 1, thermal deformation of the process chamber 1 can lead to a shift of the center of the process chamber 1 relative to the common reference plane 2. At least one (preferably two) positioning element 4 is also provided for the process chamber 1. The positioning elements are designed such that they are thermally and mechanically decoupled from the process chamber 1. If the position of the process chamber 1 changes, the fixed points of the positioning element 4 enable precise determination of the position and orientation of the process chamber 1.

[0062] As shown in Fig. 1, the base element 3 can advantageously comprise a base plate or a base element, side walls mounted on the base plate, and a cover section to which the optics module 9 is connected. Preferably, the components of the base element 3 are firmly connected to one another to form a stable frame or stand.

[0063] It is therefore proposed to provide the process chamber 1 as a closed frame or base element 3 that accommodates or supports all of the main components. The individual components typically comprise an optical system with the optics module 9, the process chamber 1 or build chamber, a lifting device 10, and the build cylinder 11. This specific construction creates a self-contained force flow, and no component is influenced by another component with regard to the effect of force. Furthermore, the components can be precisely aligned to one another. In addition, a plane is defined as a common reference plane 2 for the entire system. This is advantageously the reference plane of the optical system or the optics module 9. The accuracy-determining elements, such as main components, are coupled directly and thermally stably to this plane.Thermal stability can be achieved by positioning elements that have a low coefficient of thermal expansion, for example, made of Invar. Particularly preferably, the position of the optics module 9 relative to the reference plane 2 (and the receiving element 3) can also be designed to be adjustable, for example, by means of a vertically and / or horizontally adjustable mounting.

[0064] Fig. 2 is an advantageous embodiment of the present invention, which can be used separately or in combination with the embodiment shown in Fig. 1. Fig. 2 shows an alignment device or powder layer preparation unit. This alignment device can be viewed as an accuracy-determining component or as a main component. The alignment device with the scraper lip 20 of the coater 22 is part of the powder layer preparation device, which can be used to level the material powder on the base plate (or building plate). To align the scraper lip 20, it moves over a straight alignment bar 21. The fastening of the lip is released and the lip can be pressed against the alignment bar 21. In the process, the geometric position, and orientation of the alignment bar 21 are transferred to the scraper lip 20. The fastening of the scraper lip 20 is then reactivated.The lip is now rigid again. It is now important that the position of the alignment bar 21 does not change during machine operation, so that the wiper lip 20 can be aligned reproducibly and accurately. Errors in alignment will directly result in a defective powder coating during the build-up process of the workpiece.

[0065] The precise maintenance of the position and orientation of the alignment beam 21 is achieved by connecting the alignment beam 21 on two sides via positioning elements 23 fixed thereto. The positioning elements 23 are in turn directly connected to the common reference plane 2 or mounted thereon. Furthermore, the positioning elements 23 are made of a material with a low coefficient of thermal expansion. The positioning elements 23 are therefore made, in particular, of a temperature-invariant material. Examples of temperature-invariant materials include Invar or fiber-reinforced plastics, such as carbon fiber-reinforced or glass fiber-reinforced plastics.

[0066] Another accuracy-determining component is the Z-axis measuring system 7. Here, too, thermal displacement would lead to incorrect measurements, which in turn could directly impact the accuracy and metallurgical integrity of the component being manufactured. This is avoided by connecting the measuring system directly to the common reference plane 2 via the positioning elements 8 (or by at least partially supporting it on the positioning elements). Ideally, the positioning elements here are also made of a material with a low coefficient of thermal expansion.

[0067] Further embodiments of the present invention are illustrated in Figs. 3 and 4, with Fig. 3 illustrating the thermal expansion of the process chamber 1. By supporting the process chamber 1 at the second connection points 13 on the base element 3, which are present only on the underside, an expansion of the process chamber 1 in the vertical direction is enabled without introducing stresses into the base element 3. The flexibly connected adapter element 14 enables expansion in the horizontal and vertical directions of the top side of the process chamber 1 without inducing stresses into the base element 3 or the optics module.

[0068] In Fig. 3, the adapter element 14 is provided, which enables decoupling between the optics module 9 and the process chamber 1, with the optics module 9 and the process chamber 1 each mounted on the base element. Thus, precise beam guidance from the optics module 9 can be achieved even in the event of thermal expansion of the process chamber 1.

[0069] To further improve accuracy, as shown in Fig. 4, the positioning element can also be made of a temperature-invariant material, which enables precise position and orientation determination of the main components, and in particular of the process chamber 1. A temperature-invariant material is, for example, Invar or fiber-reinforced plastics, such as carbon fiber-reinforced or glass fiber-reinforced plastics. Ceramic or glass, for example, can also be used.

[0070] Figures 5a and 5b depict another manufacturing facility. Figure 5a shows a process chamber that thermally expands due to the process heat. Since decoupling of the main components is not provided, the focus of the laser beam shifts. Figure 5b shows that the deformations occur not only vertically but also horizontally, resulting in complex displacement of the laser beam. The thermal and mechanical deformation leads to significant inaccuracies in component manufacturing.

Claims

CLAIMS Device for the layer-by-layer construction of objects from powdered material by means of optical interaction, in particular according to the process of selective laser melting, wherein the device comprises: a process chamber (1) for providing a working space in the area of ​​a build field, at least one optical module (9) of an irradiation device for the location-selective irradiation of the material present in the area of ​​the build field, a lifting device (10) for vertically positioning a build plate to support the build field, and a collective receiving element (3) for the common connection of individual main components of the device, wherein the optical module (9) is received on the receiving element (3) at a first connection point and the process chamber (1) is received separately from the optical module (9) at at least a spaced-apart second connection point on the receiving element (3).Device according to claim 1, wherein the individual main components, such as the process chamber (1), the optical module (9), the lifting device (10) and / or a build cylinder (11), are mounted separately from one another and preferably directly on the receiving element (3). Device according to at least one of the preceding claims, wherein at least one of the main components, such as the process chamber (1), the optical module (9), the lifting device (10) and / or the build cylinder (11), is thermally decoupled and mounted on the receiving element (3), in particular by means of thermally insulating materials.

4. Device according to at least one of the preceding claims, wherein at least at the second connection point a cooling device is provided for cooling the connection point.

5. Device according to at least one of the preceding claims, wherein the process chamber (1) is mounted only at one bearing point on the receiving element (3) and / or wherein all functional carriers are mounted separately from the process chamber (1).

6. Device according to at least one of the preceding claims, wherein the main components of the device are thermally and mechanically decoupled from the process chamber (1), and an adapter element (14) is provided between the optical module (9) and the process chamber (1) for gas-tight and / or laser-safe shielding of a beam guidance area from the environment.

7. Device according to at least one of the preceding claims, wherein the adapter element (14) is flexibly designed so that a relative displacement of the process chamber (1) to the optical module (9) free from mechanical stresses is possible.

8. Device according to at least one of the preceding claims, wherein the adapter element (14) comprises a membrane and / or a sealing ring.

9. Device according to at least one of the preceding claims, wherein the adapter element (14) has an integrated protective glass to protect the optical module (9) from the process atmosphere contaminated with particles, and wherein the protective glass is preferably rigidly connected to the optical module (9) to avoid relative displacements of the protective glass to the optical module (9).

10. Device according to one of the preceding claims, wherein the individual main components have a common reference plane (2) and the individual main components are aligned to each other via the common reference plane (2), in particular by means of positioning elements made of temperature-invariant material such as Invar and / or fiber-reinforced plastics.

11. Device according to at least one of the preceding claims, wherein at least one of the main components is coupled to the common reference plane (2) by means of a positioning element for determining deviations in the orientation or positioning of the respective component.

12. Device according to at least one of the preceding claims, wherein displacements of the main components are determined electronically via measuring means (5) and preferably directly and / or simultaneously in the machine control in order to compensate for the determined displacements, in particular by adjusting the beam path.

13. Device according to at least one of the preceding claims, wherein the individual main components are at least partially mechanically connected to the common reference plane (2) via positioning elements for setting a constant distance to the common reference plane (2).

14. Device according to one of the preceding claims, wherein the reference plane of the optical module (9) is the common reference plane (2).

15. Device according to at least one of the preceding claims, wherein the receiving element (3) is a frame that at least encloses the process chamber (1) and wherein the receiving element (3) preferably also encloses the lifting device (10) and / or the construction cylinder (11). Device according to at least one of the preceding claims, wherein the device further comprises a coater (22) for preparing the powdered material and the coater (22) comprises an alignment device, and wherein, to maintain the position and orientation of the alignment device constantly, it is directly connected to the common reference plane (2) by positioning elements (23). Device according to at least one of the preceding claims, wherein the device comprises a measuring system (6) of the Z-axis (7), and, to maintain the position and orientation of the measuring system (6) constantly, it is directly connected to the common reference plane (2) by positioning elements (23).Device according to at least one of the preceding claims, wherein process monitoring systems (12) such as a camera system, a powder bed monitoring system, and / or a melting point monitoring system are provided, each of which is coupled to the common reference plane (2). Method for manufacturing articles using a device according to at least one of the preceding claims, wherein. - the position and / or orientation of at least one principal component relative to the common reference plane (2) is determined using a positioning element and - the determined displacement is compensated directly and / or simultaneously by the machine control through adjustment of the beam path of the optical module (9). Method according to claim 19, wherein the positioning elements assigned to the individual main components are used as a reference to determine the position and orientation of the main components.

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