Lifting device for carrier device of system for additive manufacturing of three-dimensional workpieces

Abstract

The invention relates to a lifting device for a carrier device of a system for additive manufacturing of three-dimensional workpieces. The lifting apparatus includes a base element, at least one first spindle attached to the base element, a lifting platform, and at least one second spindle attached to the lifting platform. Furthermore, the lifting device comprises at least one intermediate frame comprising at least one first drive means for vertically moving the intermediate frame relative to the first spindle and the base element and at least one second drive means for vertically moving the second spindle and the lifting platform relative to the intermediate frame.

Description

Technical Field

[0001] The invention relates to a lifting device of a carrier device of a system for additive manufacturing of a three-dimensional workpiece. In particular but not limited to, the additive manufacturing may be a method of selective laser melting, selective laser sintering or selective electron beam melting. Background Art

[0002] In additive (or generative) methods for producing three-dimensional workpieces and in particular in generative layering processes, it is known that an initially unshaped or intermediately shaped molding compound of a raw material (e.g., a raw material powder) is applied in the form of multiple layers to a carrier (also referred to herein as a carrier device) and the initially unshaped or intermediately shaped molding compound is solidified by irradiation at specific locations (e.g., by melting or sintering) to finally obtain a workpiece of the desired shape. The irradiation can be carried out by electromagnetic radiation, for example in the form of laser radiation, or by particle radiation, for example in the form of electron radiation. In the initial state, the molding compound can initially be in the form of particles, in the form of a powder, or in the form of a liquid molding compound, and the molding compound can be selectively solidified or, in other words, selectively solidified in a position-specific manner as a result of the irradiation. The molding compound can, for example, include ceramic, metal or plastic materials and mixtures of these materials. A variant of the generative layering process involves so-called laser beam melting in a powder bed, in which the original powder material, in particular metal and / or ceramic, is solidified into a three-dimensional workpiece by irradiation with a laser beam.

[0003] In order to produce a single workpiece layer, it is also known that a raw powder material is applied to a carrier in the form of a raw powder layer and that the raw powder material is selectively irradiated according to the geometry of the workpiece layer currently to be produced. The laser radiation penetrates the raw powder material and solidifies it, for example as a result of heating which leads to melting and / or sintering. Once the workpiece layer has been solidified, a new unprocessed layer of raw powder material is applied to the already produced workpiece layer. Known applicator devices or powder application devices can be used for this purpose. Then, the now uppermost and still unprocessed raw powder layer is irradiated. Thus, the workpiece is built up continuously layer by layer, wherein each layer defines the cross-sectional area and / or contour of the workpiece. In this context, it is also known to use CAD or comparable workpiece data to produce the workpiece substantially automatically.

[0004] It should be understood that the present invention can also provide all of the above aspects as well as the following aspects.

[0005] Before a new layer of raw material is applied, the carrier device to which the first layer has been applied is usually lowered vertically downwards. This is done by a lifting device, which for this purpose can have one or more motors, telescopic screw drives, actuators, pneumatic elements, etc., to move the carrier device vertically and then keep it at a predetermined height. The carrier device moves within the building cylinder, the side walls of which support the uncured raw material during the manufacturing process. The carrier device thus forms the bottom wall of the building cylinder.

[0006] Build sizes (particularly build heights) in additive manufacturing processes are continuing to grow. The resulting increase in build cylinder height also increases the overall height of the additive manufacturing system. This can cause problems for end users if the production floor has a low ceiling height. Therefore, solutions that reduce the height of the system are needed.

[0007] For example, one approach to solving this problem is to use telescopic screw drives. However, these telescopic screw drives require a relatively large amount of installation space, are relatively complex to manufacture and are therefore generally relatively expensive. Furthermore, in some cases, the multi-stage nature of these telescopic screw drives under load shows nonlinear deformation curves and / or different stiffnesses of the respective screw stages.

[0008] Therefore, it is desirable to provide a lifting device which is compact, easy to manufacture and inexpensive.Furthermore, a relatively low deformability of the individual elements of the lifting device or at least an accurate predictability of the deformation of the elements of the lifting device is desirable. Summary of the invention

[0009] It is therefore an object of the present invention to provide a lifting device that solves at least one of the above-mentioned problems or related problems.

[0010] This object is achieved by a lifting device for a carrier arrangement of a system for additive manufacturing of three-dimensional workpieces having the features of claim 1. The object is further achieved by a system according to claim 14. Further embodiments are given in the dependent claims.

[0011] Thus, according to a first aspect, the invention relates to a lifting device for a carrier device of a system for additive manufacturing of three-dimensional workpieces. The lifting device comprises a base element, at least one first spindle attached to the base element, a lifting platform and at least one second spindle attached to the lifting platform. The lifting device also comprises at least one intermediate frame, the at least one intermediate frame comprising at least one first drive device for vertically moving the intermediate frame relative to the first spindle and the base element and at least one second drive device for vertically moving the second spindle and the lifting platform relative to the intermediate frame.

[0012] In particular, the system may be a system for selective laser melting or sintering, which for example comprises one or more of the above-mentioned features. Furthermore, the system may be a system for selective electron beam melting or another system for additive manufacturing, which requires a vertically movable carrier device for the manufactured workpiece.

[0013] The base element can be a structural base, in particular a structural mounting base. The base element can, for example, include a plate and / or a grid structure. In particular, the base element can be configured to be arranged on the floor or fixed to the floor, and thus can achieve fixed attachment of the first spindle to the floor. If multiple first spindles are provided, the base element can achieve fixed relative positioning of the first spindles relative to each other. The base element can be a substrate. In particular, the base element can be the bottom plate of the system. For example, the base element can stand directly on the floor of the production workshop, or stand on the floor and / or fasten to the floor using corresponding feet and / or damping elements. The base element can also be part of the production workshop floor. The first spindle can be, for example, detachably attached to the base element such as by screws, bolts, etc. In addition, the first spindle can also be firmly connected to the base element, such as welded on the base element. The first spindle can extend vertically upward from the base element. In other words, the base element can be in the form of a substantially plate-shaped substrate and define an xy plane, wherein the first spindle extends perpendicular to the base element along the z direction.

[0014] The lifting platform may have any shape. The lifting platform may comprise a plate-like element and / or may be plate-like or at least substantially plate-like. In particular, the lifting platform may comprise a plate assembly. The lifting platform may be configured to serve as a carrier device or to comprise a carrier device, or the lifting platform may be configured to serve as a further intermediate frame or to comprise a further intermediate frame.

[0015] For attaching the second spindle to the lifting platform, the above options for attaching the first spindle to the base element apply accordingly. The second spindle can extend perpendicularly to the plane in which the lifting platform extends. For example, the lifting platform can be arranged parallel to the base element. The extension directions of the first spindle and the second spindle can be parallel to each other and in particular perpendicular to the base element and the lifting platform.

[0016] The intermediate frame may have any shape. For example, the intermediate frame may comprise a plate to which the first drive means and the second drive means are attached. However, the intermediate frame may also not comprise such a (common) plate, but rather comprise a first plate to which the first drive means (and optionally further first drive means) are attached and a second plate to which the second drive means (and optionally further second drive means) are attached. Furthermore, the intermediate frame may not comprise any plates at all, but rather consist of a linkage mechanism, wherein the drive means are attached to the rods of the linkage mechanism.

[0017] The first drive device and the second drive device can each include a ball screw drive, in particular a ball screw drive with a shaft drive. The first drive device and the second drive device can be designed so that the first drive device and the second drive device each include a drive (in particular a ball screw drive) that rotates around a spindle under appropriate control and power supply, wherein the spindle itself is fixed and does not rotate. In this way, the first drive device is vertically moved relative to the first spindle. In addition, a vertical movement of the second spindle relative to the second drive device is performed in this way.

[0018] The lifting platform may comprise a carrier device of the system.

[0019] For example, the lifting platform may include and / or represent a carrier device in the form of a carrier plate. For example, the lifting platform may include a plate assembly, wherein the uppermost plate of the plate assembly represents the carrier device. The plate assembly may, for example, be attached to a plate-shaped element of the lifting platform by means of screws. In particular, the raw material may be applied to the carrier plate. The lifting platform including the carrier device may mean that the carrier device is rigidly connected to another element of the lifting platform and / or that the carrier device forms a one-piece component together with another element of the lifting platform. In this case, it can be said that the lifting device is two-stage, because the lifting device includes two moving planes, namely the plane of the intermediate frame and the plane of the lifting platform. In other embodiments (see below), at least one further additional stage (in particular above the second stage) may be provided.

[0020] The lifting platform may comprise a further intermediate frame, wherein the lifting device further comprises the further lifting platform and at least one third spindle attached to the further lifting platform. The further intermediate frame may comprise at least one third drive device for vertically moving the third spindle and the further lifting platform relative to the further intermediate frame.

[0021] Thus, the lifting device can be three-stage or have further stages, so that the lifting device can be four-stage, five-stage, etc. For the attachment of the third spindle to the further lifting platform and for the drive means, the above description regarding the second spindle and the second drive means, respectively, can apply. The further lifting platform can comprise a carrier device of the system.

[0022] The first drive device and the second drive device can be controlled independently of each other.

[0023] In particular, the first drive device and the second drive device may each include a motor (e.g. a servomotor) and / or an actuator of the first drive device and the second drive device itself. In addition, the first drive device and the second drive device may be controlled independently of each other, for example via corresponding gearboxes. For example, a common motor and a gearbox coupled to the motor and the first drive device and the second drive device may be provided, the gearbox driving only the first drive device in a first gearbox position and only the second drive device in a second gearbox position. In addition, a third gearbox position may be provided, in which the first drive device and the second drive device are driven simultaneously.

[0024] The first drive means may include a first motor, and the second drive means may include a second motor.

[0025] Thus, the first drive device and the second drive device can be controlled separately from each other by the control device of the lifting device. Separate control includes, for example, controlling one of the first drive device and the second drive device while the other drive device remains stationary, including controlling the first drive device and the second drive device in opposite directions and / or controlling the first drive device and the second drive device at different speeds.

[0026] The lifting device may further comprise at least one further first spindle attached to the base element.The intermediate frame may comprise at least one further first drive means for vertically moving the intermediate frame relative to the further first spindle and the base element.

[0027] For the additional first spindles and the additional first drive means, the above aspects and details discussed with respect to the first spindles and the first drive means may apply. In particular, two, three or four first spindles and two, three or four first drive means associated with the two, three or four first spindles may be provided.

[0028] The first drive device and the further first drive device can be controlled independently of one another.

[0029] In this way, the intermediate frame can be tilted and / or oriented horizontally (hereinafter also: leveled), for example (in particular relative to the ground plane). At the same time, the carrier device can be tilted and / or leveled.

[0030] The lifting device may further comprise a control unit for independently controlling the first drive device and the second drive device.

[0031] The control unit can be, for example, the control unit of the system or be formed by the control unit of the system.The control unit can comprise a microprocessor and a (volatile or non-volatile) memory, wherein a control program is stored in the memory, which enables the corresponding drive device to be controlled.

[0032] The lifting device may further comprise at least one further second main shaft attached to the lifting platform.The intermediate frame may comprise at least one further second drive means for vertically moving the further second main shaft and the lifting platform relative to the intermediate frame.

[0033] For the additional second spindles and the additional second drive means, the above aspects and details discussed with respect to the second spindles and the second drive means may apply. In particular, two, three or four second spindles and two, three or four second drive means associated with the two, three or four second spindles may be provided.

[0034] The second drive device and the further second drive device can be controlled independently of one another.

[0035] In this way, the lifting platform can be tilted and / or leveled, for example, in particular relative to a reference plane, such as a ground plane, a coater, laser optics or a process chamber floor. At the same time, the carrier device can be tilted and / or leveled.

[0036] The lifting device may include at least three second spindles attached to the lifting platform, wherein the intermediate frame includes at least three second drive devices for vertically moving the three second spindles and the lifting platform relative to the intermediate frame. In addition, the lifting device may include a device for detecting the orientation of the lifting platform. The control unit may be configured to control the second drive devices based on detection data of the device for detecting the orientation of the lifting platform so that the lifting platform is horizontally oriented.

[0037] By providing at least three second spindles, the lifting platform can be horizontally oriented (leveled), in particular relative to a reference plane, such as a ground plane, a coater, laser optics or a process chamber floor. In this case, the lifting platform can be tilted about at least two non-parallel axes, which can allow full leveling. The device for detecting the orientation can, for example, comprise a spirit level, an electronic spirit level, a plurality of triangulation lasers and / or a corresponding sensor, which is used, for example, to detect the earth's gravity, for example comprising a suitable micro-electro-mechanical system (MEMS). If the sensor, for example, detects that the lifting platform is not oriented horizontally, a corresponding second drive device can be controlled which orients the lifting platform horizontally, i.e. levels the lifting platform.

[0038] The means for detecting the orientation of the lifting platform may comprise at least one linear encoder.

[0039] The linear encoder may, for example, enable high-precision (eg, sub-micron precision) positioning of the lifting platform relative to one or more guide rails.The linear encoder may be a so-called glass scale linear encoder.

[0040] The lifting device may further comprise at least one guide rail attached to the base element and at least one track guide attached to the intermediate frame, the at least one track guide being used to guide the intermediate frame during a vertical movement of the intermediate frame relative to the first spindle and the base element.

[0041] The guide rail in combination with the track guide can prevent tilting or twisting of the intermediate frame and / or tilting or twisting of the lifting platform, so that the two elements always remain horizontally aligned. This is particularly applicable to the case where only the first spindle and / or the second spindle are provided. The track guide can, for example, include one or more carriages. In particular, at least two track guides can be provided for one or more guide rails.

[0042] The base element may comprise a substrate. In particular, the base element may be a substrate.

[0043] According to a second aspect, the invention relates to a system for additive manufacturing of a three-dimensional workpiece, the system comprising the lifting device of the first aspect.

[0044] All sub-aspects and details of the above-described lifting device can be arranged accordingly in the lifting device of the system. The additive manufacturing system can be, for example, a system for selective laser sintering, for selective laser melting or for selective electron beam melting. Apart from the lifting device, the system can have one or more of the above-described features of the corresponding known systems.

[0045] The system for additive manufacturing of three-dimensional workpieces comprises, for example, a carrier device for applying powder in multiple layers so as to form a powder bed. In addition, one or more powder applying devices can be provided, one or more powder applying devices for applying powder and, if necessary, for applying powders of different materials. A separate powder applying device can be provided for each material. The carrier device can be moved vertically downward by means of a lifting device so that the uppermost powder layer is always maintained at the same height relative to the building chamber of the system. In addition, the system can include one or more irradiation units. The irradiation units each include a beam source (in particular a laser beam source) and an optical system having one or more optical components for shaping and deflecting the beam (e.g., a beam expander, a focusing unit, a scanning device, an F-θ lens). BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The present invention is described below with reference to the accompanying drawings. The present invention represents:

[0047] Figure 1: A schematic side view of a system for additive manufacturing of a three-dimensional workpiece including a lifting device according to an embodiment of the present disclosure;

[0048] Figure 2 : A perspective view of a lifting device according to a first embodiment of the present disclosure, wherein the lifting device comprises three first main shafts and three second main shafts, wherein part (a) represents a fully retracted state of the lifting device, and part (b) represents a fully extended state of the lifting device;

[0049] Figure 3 : A side view of a lifting device according to a first embodiment, wherein part (a) represents a fully retracted state, and part (b) represents a fully extended state;

[0050] Figure 4 : a perspective view of a lifting device according to a first embodiment in a partially retracted state of the lifting device;

[0051] Figure 5 : A side view of a lifting device according to a second embodiment of the present disclosure, wherein the lifting device includes two first main shafts and three second main shafts, wherein part (a) represents a fully retracted state of the lifting device, and part (b) represents a fully extended state of the lifting device; and

[0052] Figure 6 : A side view of a lifting device according to a third embodiment of the present disclosure, wherein the lifting device includes a first main shaft and three second main shafts, wherein part (a) represents a fully retracted state of the lifting device, and part (b) represents a fully extended state of the lifting device. DETAILED DESCRIPTION

[0053] Figure 1 A system 1 for additive manufacturing of a three-dimensional workpiece 2 is shown, wherein the system 1 comprises a lifting device 20 for a carrier device 5 of the system 1. Apart from the lifting device 20, the system 1 is a conventional system for selective laser melting with known components. The selective laser melting technology used by the system 1 is known to a person skilled in the art and is only briefly explained here with reference to selective laser melting in a powder bed 3.

[0054] First, a first raw material powder layer is applied to a carrier 5 (also referred to as a carrier device 5) of the system 1, and the first raw material powder layer is irradiated in a position-specific manner by one or more laser beams 7a, 7b so that the desired area of ​​the powder is solidified. This example shows a system 1 having two irradiation units, each of which includes a laser 9a, 9b and an optical system 11a, 11b. Therefore, the irradiation unit including the laser 9a and the optical device 11a is configured to emit a laser beam 7a and guide the laser beam to the desired position of the uppermost powder layer of the powder bed 3. In addition, the irradiation unit including the laser 9b and the optical device 11b is configured to emit a laser beam 7b and guide the laser beam to the desired position of the uppermost powder layer of the powder bed 3. The optical devices 11a, 11b each include components for beam shaping and beam deflection, such as lenses, deflection mirrors, scanning mirrors, etc.

[0055] All components of the system 1 are controlled by a control unit 13 , in particular the lasers 9a , 9b , the scanning mirrors of the optics 11a , 11b , the movement of the carrier 5 by means of the lifting device 20 and the function of the powder application device 15 described below.

[0056] After the first powder layer has been cured as desired, another powder layer is applied to the previous powder layer, and this top layer is again irradiated and cured.

[0057] In order to always keep the distance between the uppermost layer and the optical unit constant, the carrier 5 can be lowered and / or the optical unit can be raised during the building process (along the vertical direction defined here as the z-direction). In this way, the three-dimensional workpiece 2 to be produced is built up layer by layer. The uncured powder can then be removed and optionally reused.

[0058] A horizontally movable powder application device 15 is used to apply powder, which has suitable components for applying powder in the form of multiple layers (for example, at least one roller and / or at least one scraper and / or at least one pusher and / or at least one storage container, etc.).

[0059] The gas supply 17 supplies an inert gas to the build chamber 19 of the system 1, so that an inert gas atmosphere prevails within the build chamber 19. Furthermore, a gas extraction system (not shown) may be provided, which sucks the inert gas back from the build chamber 19, so that a gas flow through the build chamber 19, in particular through the powder bed 3, is generated.

[0060] In the following, the lifting device 20 is described in detail with reference to a plurality of embodiments. In other words, the lifting device according to each of the following embodiments can be used as Figure 1 The system 1 includes a lifting device 20 .

[0061] Figure 2 A perspective view showing a lifting device according to a first embodiment of the present disclosure is shown. Figure 2 Part (a) shows the fully retracted state of the lifting device 20a, and part (b) shows the fully extended state of the lifting device 20a.

[0062] In the following, reference numerals 20a, 20b and 20c are used for specific embodiments of the lifting device 20. In other words, any of the embodiments described below can be used as a lifting device 20 (e.g. Figure 1 ). Therefore, reference numeral 20 includes "sub-reference numerals" 20a, 20b and 20c. The same applies to the other reference numerals used herein with lower case letters a, b and c, respectively. The lifting device 20 is generally configured to move the carrier device 5 of the system vertically (ie, along the z direction).

[0063] For greater clarity, in the following figures, only the representation of the extended state has reference numerals. It should be understood that corresponding elements of the lifting device 20 in the retracted state have the same reference numerals as the same elements in the extended state.

[0064] The lifting device 20a comprises a base element in the form of a base plate 22 and three first spindles 24a, 24b, 24c (hereinafter collectively referred to as first spindles 24) attached to the base plate 22 by screws. When the terms "first", "second", "third", etc. are used herein, this is only for the purpose of linguistic distinction of the respective elements. For example, the "first spindle" 24 of the lower layer (or also: lower level) of the lifting device 20 is linguistically distinguished from the "second spindle" 26 of the upper level.

[0065] The plate-like base element 22 shown in the figures should not be understood restrictively, and the base element may also be provided as a non-plate-like element, for example as a frame structure to which the one or more first spindles 24 are attached.

[0066] The spindles 24 and 26 are threaded rods, so the spindles have threads on the sides of the spindles. As long as the spindles are not rotatably mounted, the spindles 24 are firmly connected to the base plate 22. The spindles 24 each extend perpendicularly to the base plate 22 in the z direction.

[0067] The lifting device 20a also includes a lifting platform 28 having three second spindles 26a, 26b, 26c (hereinafter generally referred to as second spindles 26) attached to the lifting platform. In the embodiment shown, the lifting platform 28 includes a plate-like element. The second spindles 26 each extend downwardly from the lifting platform 28 perpendicular to the lifting platform in the z-direction. An intermediate layer in the form of an intermediate frame 30 is arranged between the substrate 22 and the lifting platform 28. In the embodiment shown, the intermediate frame 30 includes two horizontally extending plate-like elements and a connecting element located between the two horizontally extending plate-like elements. Ultimately, the specific design of the intermediate frame 30 is at the discretion of those skilled in the art, so that a variety of possible designs can be imagined.

[0068] The intermediate frame 30 comprises three first drive devices 32a, 32b, 32c associated with the respective first spindles 24a, 24b, 24c. More precisely, the drive device 32a interacts with the spindle 24a and / or the drive device 32a constitutes a drive for the spindle. The same applies to the drive devices 32b, 32c and the associated spindles 24b, 24c. The intermediate frame 30 also comprises three second drive devices 34a (hidden in the figure and therefore not shown), 34b, 34c associated with the respective second spindles 26a, 26b, 26c. More precisely, the drive device 34a interacts with the spindle 26a and / or the drive device 32a constitutes a drive for the spindle. The same applies to the drive devices 34b, 34c and the associated spindles 26b, 26c.

[0069] The first drive device 32 (collectively for 32a, 32b, 32c) and the second drive device 34 (collectively for 34a, 34b, 34c) are each firmly connected to another element of the intermediate frame 30. In the embodiment shown, the drive devices 32 and 34 are each attached to a plate of the intermediate frame, and the associated spindles 24 and 26 are guided through associated holes in the corresponding plates of the intermediate frame 30.

[0070] The drive devices 32 and 34 each comprise a ball screw with a shaft drive. More precisely, the drive devices 32 and 34 are used to rotate the ball screw around the (fixed) spindles 24 and 26, respectively, which results in a relative movement of the spindle and the drive device due to the threads of the spindles.

[0071] In this way, driving the drive device 32 causes the vertical movement of the intermediate frame 30 relative to the first main shaft 24 and the base plate 22. In addition, driving the second drive device 34 causes the vertical movement of the second main shaft 26 and the lifting platform 28. In this way, the movement of the first drive device 32 and the movement of the second drive device 34 both cause the movement of the lifting platform 28 relative to the base plate 22. In other words, the movement of the first drive device 32 and the movement of the second drive device 34 can both cause the vertical raising or lowering of the lifting platform 28.

[0072] In one embodiment, the carrier device 5 is directly attached to the lifting platform 28 , for example fastened thereto with screws. Alternatively, the lifting platform 28 may represent the carrier device 5 .

[0073] In other embodiments (not shown), the lifting device is a lifting device with more than two stages and a further (third) drive device is arranged on the lifting platform 28, which thus represents a further intermediate frame. The third drive device in turn drives an associated third spindle, which is firmly connected to the further lifting platform at its upper end. For example, the carrier device 5 can be attached to the lifting platform, which in this particular embodiment represents a three-stage lifting device.

[0074] In one embodiment, the first drive device 32 can be controlled independently of the second drive device 34. For example, a separate motor (particularly a servomotor) or actuator can be provided in each of the drive devices 32, 34, each of which can be controlled separately by a control unit (e.g., by the control unit 13). Therefore, if only the first drive device 32 is operated without the second drive device 34, only the "lower stage" (or "first stage") of the lifting device 20a moves. If only the second drive device 34 is operated without the first drive device 32, only the "upper stage" (or "second stage") of the lifting device 20a moves. If the first drive device and the second drive device move simultaneously, the two stages move simultaneously, so that the lifting platform 28 can move (i.e., rise or fall) faster relative to the substrate 22.

[0075] In a further embodiment, the first drive device 32 and / or the second drive device 34 can be controlled individually relative to each other. Thus, each of the individual drives 32a, 32b, 32c and / or each of the individual drives 34a, 34b, 34c can be controlled individually. In this way, for example, the (e.g. non-horizontal) orientation of the lifting platform 28 can be changed and in particular can be adjusted so that the lifting platform 28 is oriented horizontally (in particular horizontally relative to the ground or parallel to the base plate 22). In other words, the lifting platform 28 can be leveled.

[0076] Since three drive devices 24, 26 are provided for each of the lower and upper stages, the intermediate frame 30 and the lifting platform 28 can be tilted about two non-parallel axes. Therefore, the intermediate frame 30 and the lifting platform 28 can be fully leveled. Leveling the lifting platform 28 means that the carrier device 5 connected to the lifting platform is also leveled, which may be necessary during the additive manufacturing process, for example, to avoid any quality loss.

[0077] In order to orient the lifting platform 28 and the associated orientation of the carrier device 5, the lifting device 20 may include a device for detecting the orientation of the lifting platform 28. For example, the device may be a sensor device arranged in the lifting platform 28 or the carrier device 5. The sensor device may, for example, include a triangulation laser system or an electronic level, in particular one or more micro-electromechanical systems (MEMS), which are suitable for detecting the earth's gravity. In addition, the device for detecting the orientation of the lifting platform 28 may include a linear encoder. The linear encoder may, for example, be arranged in combination with the guide rails described below, and in particular may detect the position of the track guide relative to the corresponding guide rail.

[0078] The lifting device 20a also includes two guide rails 36a and 36b. The guide rails 36a, 36b are fixedly connected to the base plate 22 and extend perpendicularly to the base plate, and the guide rails 36a, 36b are parallel to the main shafts 24 and 26. The guide rails 36a, 36b guide the associated track guides 38a, 38b fixedly connected to the intermediate frame 30. In this way, the intermediate frame 30 is guided during the vertical movement of the intermediate frame along the guide rails 36a, 36b, thereby preventing the distortion of the intermediate frame 30. In the first embodiment shown, two track guides are provided for each guide rail 36 (one track guide is above the other track guide), which leads to better stability of the guided element (intermediate frame 30), in particular to prevent tilting. The track guides 38 can each be provided in the form of a carriage. However, the number of track guides 38 of each guide rail can be increased and decreased as needed, wherein a greater number of track guides 38 can contribute to increasing the stability of the intermediate frame 30.

[0079] Figure 2 Part (a) shows the fully retracted state of the lifting device 20a, wherein the first stage and the second stage are retracted so that the lifting platform 28 is at the lowest possible height. Figure 2 Part (b) shows the fully extended state of the lifting device 20a, wherein the first stage and the second stage are extended so that the lifting platform 28 is at the highest possible height.

[0080] Figure 3 Shown according to Figure 2A side view (along the side of the lifting device 20a of the first embodiment) Figure 2 The elements shown correspond to Figure 2 Part (a) and Figure 2 element of part (b).

[0081] Figure 4 Shown according to Figure 2 A perspective view of a lifting device 20a of a first embodiment, similar to Figure 2 View of. Figure 4 In the illustration of FIG, a partially retracted or partially extended state of the lifting device 20a is shown. Here, the lower (first) stage is extended and the upper (second) stage is retracted. Thus, the first drive device 32 can be controlled independently of the second drive device 34, so that any desired state of the lifting device 20a can be assumed with respect to the position of the intermediate frame 30 relative to the base plate 22 and the position of the lifting platform 28 relative to the intermediate frame 30.

[0082] Figure 5 A side view of a lifting device 20b according to a second embodiment of the present disclosure is shown, wherein the lifting device comprises two first main shafts 24a, 24b and three second main shafts 26a, 26b, 26c. Associated with each of these main shafts 24 and 26, the lifting device 20c has two first drive units 32a, 32b and three second drive units 34a, 34b, 23c. Part (a) shows the fully retracted state of the lifting device 20b, and part (b) shows the fully extended state of the lifting device 20b.

[0083] exist Figure 5 In the second embodiment example, only some elements are provided with reference numerals, whereby elements which clearly correspond to elements of the first embodiment example are regarded as being provided with the same reference numerals.

[0084] The lifting device 20b of the second embodiment example is identical to the lifting device 20a of the first embodiment example, except for the number of first spindles 24 and first drive devices 32. The above description of the first embodiment example applies correspondingly to the second embodiment example.

[0085] The advantage of the second embodiment example over the first embodiment example may be that the first spindle 24c and the first drive 32c can be omitted. Adequate guidance and stabilization of the intermediate frame 30 during the movement of the lower stage is ensured by the guide rails 36 and the associated track guides 38. Adequate possibilities for changing the alignment (leveling) of the lifting platform 28 are ensured by the provision of three second spindles 26.

[0086] An advantage of the first embodiment example over the second embodiment example may be that larger loads can be lifted (because the total load is distributed over the three first spindles 24). In addition, the intermediate frame 30 can already be aligned using the three first spindles 24, which results in greater flexibility in the alignment. In particular in conjunction with the first embodiment example, for example, the guide rails 36 and the associated rail guides 38 may also be omitted. This applies in principle to all embodiments mentioned herein.

[0087] Figure 6 A side view of a lifting device 20c according to a second embodiment of the present disclosure is shown, wherein the lifting device comprises a first main shaft 24a and three second main shafts 26a, 26b, 26c. Associated with each of these main shafts 24 and 26, the lifting device 20c comprises a first drive unit 32a and three second drive units 34a, 34b, 23c. Part (a) shows the fully retracted state of the lifting device 20c, and part (b) shows the fully extended state of the lifting device 20c.

[0088] exist Figure 6 In the third embodiment of the present invention, only some elements are provided with reference numerals, wherein elements which clearly correspond to elements of the first embodiment example are considered to be provided with the same reference numerals.

[0089] The lifting device 20c of the third embodiment is the same as the lifting device 20a of the first embodiment and the lifting device 20b of the second embodiment except for the number and arrangement positions of the first spindles 24 and the first drive devices 32. The above description of the first embodiment applies to the third embodiment accordingly.

[0090] The advantage of the third embodiment over the first and second embodiments may be that the number of first spindles 24 can be reduced to one, which saves costs and material. Adequate guidance and stabilization of the intermediate frame 30 during the movement of the lower stage is ensured by the guide rails 36 and the associated track guides 38. Adequate possibility of changing the orientation of the lifting platform 28 is ensured by providing three second spindles 26.

[0091] It should be pointed out that the number of first spindles 24 and the number of second spindles 26 is ultimately arbitrary in each case, so that embodiments are conceivable, for example, with the following number of first spindles / second spindles: the number of first spindles / second spindles is 1 / 1, 1 / 2, 1 / 3, 1 / 4, 2 / 1, 2 / 2, 2 / 3, 2 / 4, 3 / 1, 3 / 2, 3 / 3, 3 / 4, 4 / 1, 4 / 2, 4 / 3, 4 / 4, etc. Among them, as mentioned above, the series of 3 / 3, 2 / 3 and 1 / 3 may be particularly advantageous.

[0092] Furthermore, multi-stage lifting devices are possible, which have more than two stages, wherein at least one spindle with an associated drive is provided for each stage. For example, two-stage, three-stage, four-stage, five-stage, etc. lifting devices are conceivable.

[0093] With the above-described technology, a lifting device can be provided which is compact when retracted and which, when fully extended, allows a large distance between the substrate 22 and the lifting platform 28. In this way, large, in particular tall, workpieces can also be produced in low production halls, since the overall height of the system 1 remains relatively low. In addition, the proposed technology allows precise and stable positioning, in particular for deformations of the lifting device 20. In addition, a safe and stable guidance can be ensured. In addition, an alignment, in particular a leveling, of the lifting platform 28 can be achieved.

[0094] A 2-stage "multi-stage" lifting column as described in the above embodiment (3-stage or more-stage lifting columns are also conceivable) can be used for position-accurate electric height adjustment with heavy loads (e.g. 500 kg to 5000 kg), in particular for construction work and for safe, stable guidance over the entire stroke with small external dimensions. An axis drive (servo drive) with a rotating ball screw arranged antiparallel to one another in both actuation directions can accommodate higher loads than would otherwise be possible by dividing the total stroke into two small individual strokes.

[0095] Depending on the number of drives and the number of roller track guides, different positioning accuracies result. This is particularly important in the additive industry with large build jobs.

Claims

1. A lifting device (20, 20a, 20b, 20c) of a carrier device (5) of a system (1) for additive manufacturing of a three-dimensional workpiece (2), comprising: - a base element (22); - at least one first spindle (24a, 24b, 24c) attached to said base element (22); - a lifting platform (28); - at least one second spindle (26a, 26b, 26c) attached to the lifting platform (28); and - at least one intermediate frame (30), comprising at least one first drive device (32a, 32b, 32c) for vertically moving the intermediate frame (30) relative to the first spindle (24a, 24b, 24c) and the base element (22), and at least one second drive device (34a, 34b, 34c) for vertically moving the second spindle (26a, 26b, 26c) and the lifting platform (28) relative to the intermediate frame (30).

2. The lifting device (20, 20a, 20b, 20c) according to claim 1, wherein: The lifting platform (28) comprises the carrier device (5) of the system (1).

3. The lifting device (20, 20a, 20b, 20c) according to claim 1, wherein: The lifting platform (28) comprises a further intermediate frame, and wherein the lifting device (20, 20a, 20b, 20c) further comprises: - Additional lifting platforms; and - at least one third main shaft attached to said further lifting platform, Therein, the further intermediate frame comprises at least one third driving device for vertically moving the third main shaft and the further lifting platform relative to the further intermediate frame.

4. The lifting device (20, 20a, 20b, 20c) according to any one of claims 1 to 3, wherein: The first drive device (32a, 32b, 32c) and the second drive device (34a, 34b, 34c) can be controlled independently of each other.

5. The lifting device (20, 20a, 20b, 20c) according to claim 4, wherein: The first drive means (32a, 32b, 32c) includes a first motor, and the second drive means (34a, 34b, 34c) includes a second motor.

6. The lifting device (20, 20a, 20b, 20c) according to any one of claims 1 to 5, further comprising: - at least one further first spindle (24a, 24b, 24c) attached to said base element (22), Wherein, the intermediate frame (30) comprises at least one additional first drive device (32a, 32b, 32c) for vertically moving the intermediate frame (30) relative to the additional first spindle (24a, 24b, 24c) and the base element (22).

7. The lifting device (20, 20a, 20b, 20c) according to claim 6, wherein: The first drive device (24a, 24b, 24c) and the further first drive device (24a, 24b, 24c) can be controlled independently of each other.

8. The lifting device (20, 20a, 20b, 20c) according to any one of claims 1 to 7, further comprising: - a control unit (13) for independently controlling the first drive means (32a, 32b, 32c) and the second drive means (34a, 34b, 34c).

9. The lifting device (20, 20a, 20b, 20c) according to any one of claims 1 to 8, further comprising: - at least one further second spindle (26a, 26b, 26c) attached to the lifting platform (28), The intermediate frame (30) includes at least one additional second drive device (34a, 34b, 34c) for vertically moving the additional second spindle (26a, 26b, 26c) and the lifting platform (28) relative to the intermediate frame (30).

10. The lifting device (20, 20a, 20b, 20c) according to claim 9, wherein: The second drive device (34a, 34b, 34c) and the further second drive device (34a, 34b, 34c) can be controlled independently of each other.

11. The lifting device (20, 20a, 20b, 20c) according to claims 8 and 10, further comprising: - at least three second main shafts (26a, 26b, 26c) attached to the lifting platform, wherein the intermediate frame (30) comprises at least three second drive means (34a, 34b, 34c) for vertically moving the three second main shafts (26a, 26b, 26c) and the lifting platform (28) relative to the intermediate frame (30); and - means for detecting the orientation of the lifting platform (28), The control unit (13) is configured to control the second drive device (34a, 34b, 34c) based on detection data of the device for detecting the orientation of the lifting platform (28), so that the lifting platform (28) is oriented horizontally.

12. The lifting device (20, 20a, 20b, 20c) according to claim 11, wherein: The means for detecting the orientation of the lifting platform (28) comprises at least one linear encoder.

13. The lifting device (20, 20a, 20b, 20c) according to any one of claims 1 to 12, further comprising: - at least one guide rail (36a, 36b) attached to the base element (22); as well as - at least one rail guide (38a, 38b) attached to the intermediate frame (30), the at least one rail guide being used to guide the intermediate frame (30) during its vertical movement relative to the first spindle (24a, 24b, 24c) and the base element (22).

14. The lifting device (20, 20a, 20b, 20c) according to any one of claims 1 to 13, wherein: The base element (22) comprises a base plate (22).

15. A system (1) for additive manufacturing of a three-dimensional workpiece (2), comprising a lifting device (20, 20a, 20b, 20c) according to any one of claims 1 to 14.

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