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

Abstract

The present 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, and further includes at least one intermediate frame including 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.

Description

[Technical Field]

[0001] The present invention relates to a lifting apparatus for a carrier device of a system for additive manufacturing of three-dimensional workpieces, in particular, but without limitation, additive manufacturing may be selective laser melting, selective laser sintering or selective electron beam melting. [Background technology]

[0002] In layer-by-layer (or generative) methods for the production of three-dimensional workpieces, in particular in generative deposition processes, it is known to apply an initially shapeless or shape-neutral molding compound of raw materials (e.g. raw material powder) in layers to a carrier (also referred to herein as a carrier device) and solidify it by site-specific irradiation (e.g. by melting or sintering) to ultimately obtain a workpiece of the desired shape. The irradiation may be carried out using electromagnetic radiation, for example in the form of laser irradiation, or using particle radiation, for example in the form of electron radiation. In the initial state, the molding compound may initially be in the form of granules, powder, or liquid molding compound, which may be selectively, in other words site-specifically, solidified as a result of the irradiation. The molding compound may comprise, for example, ceramic, metal, or plastic materials, as well as mixtures of these materials. One variant of the generative deposition process relates to so-called laser beam melting in a powder bed, in which in particular metal and / or ceramic powder raw materials are solidified into a three-dimensional workpiece by irradiation with a laser beam.

[0003] To produce individual workpiece layers, it is also known to apply raw powder material in the form of a raw powder layer to a carrier and irradiate it selectively and depending on the geometry of the workpiece layer to be produced. Laser radiation penetrates the raw powder material as a result of heating, solidifying it and causing melting or sintering. Once the workpiece layer has solidified, a new layer of raw powder raw material is applied to the previously produced workpiece layer. Known coater arrangements or powder application devices may be used for this purpose. The now-uppermost raw powder layer is then irradiated. As a result, the workpiece is successively built up layer by layer, with each layer defining the cross-sectional area and / or contour of the workpiece. In this context, the use of CAD or comparable workpiece data to essentially automatically produce workpieces is also known.

[0004] It should be understood that all of the above-mentioned embodiments as well as the following embodiments may be provided within the present invention as well.

[0005] Before applying a new layer of material, the carrier device on which the first layer has been applied is typically lowered downward. This is accomplished by a lifting device, which for this purpose may have one or more motors, telescopic screw drives, actuators, pneumatic elements, etc., for vertically moving the carrier device and subsequently holding it at a predetermined height. The carrier device moves inside a build cylinder, the side walls of which support the unsolidified material during the manufacturing process. The carrier device thus forms the bottom wall of the build cylinder.

[0006] The build size (specifically, the build height) in additive manufacturing processes is continuously growing. The resulting increase in build cylinder height likewise increases the overall height of the additive manufacturing system. This creates problems for end users when the ceiling height of the production site is low. Therefore, there is a need for a solution to reduce the system height.

[0007] One approach to solving this problem is, for example, the use of telescopic screw drives. However, these screw drives require a relatively large installation space, are relatively complex to manufacture, and are therefore generally relatively expensive. Furthermore, in some situations, the multi-stage nature of these telescopic screw drives operating under load results in nonlinear deformation curves and / or different stiffnesses for each screw stage.

[0008] It is therefore desirable to provide a lifting device that is compact, easy to manufacture, and inexpensive. Furthermore, it is desirable to have relatively low deformation of the individual elements of the lifting device, or at least to have precisely predictable deformation of the elements of the lifting device. Summary of the Invention [Problem to be solved by the invention]

[0009] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a lifting device that overcomes at least one of the above or related problems. [Means for solving the problem]

[0010] This object is addressed by a lifting apparatus for a carrier device of a system for additive manufacturing of three-dimensional workpieces having the features of claim 1.

[0011] This object is further addressed by a system according to claim 14. Further embodiments are provided in the subclaims.

[0012] Thus, according to a first aspect, the present invention relates to a lifting device of a carrier device of a system for additive manufacturing of three-dimensional workpieces, the lifting device comprising 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 further comprising 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.

[0013] In particular, the system may be a system for selective laser melting or sintering, including, for example, one or more of the features described above. Furthermore, the system may be a system for selective electron beam melting or another system for additive manufacturing that requires a vertically movable carrier device for the manufactured workpieces.

[0014] The base element is a structural base, specifically a structural assembly base. The base element may, for example, include a plate and / or a grid structure. In particular, the base element may be configured to be placed on or fixed to the floor, thus enabling a stationary attachment of the first spindle to the floor. If several first spindles are provided, the base element may enable a fixed relative positioning of the first spindles with respect to one another. The base element may be a base plate. In particular, the base element may be a bottom plate of the system. The base element may, for example, stand directly on the floor of the production site or stand on and / or be fastened to the floor with corresponding feet and / or damping elements. The base element may also constitute part of the floor of the production site. The first spindle may be releasably attached to the base element, for example, using screws, bolts, etc. Furthermore, the first spindle may also be rigidly connected to the base element, for example, welded onto the base element. The first spindle may extend vertically upward from the base element, in other words the base element may be essentially in the form of a plate-like base plate and define an xy-plane, the first spindle extending perpendicular to this xy-plane along the z-direction.

[0015] The lifting platform may have any shape, it may include plate-like elements and / or may be plate-like or at least substantially plate-like.

[0016] In particular, the lifting platform may include the plate package, may serve as or be configured to include a carrier device, or may serve as or be configured to include a further intermediate frame.

[0017] For mounting the second spindle on the lifting platform, the options described above for mounting the first spindle on the base element apply accordingly. The second spindle may extend perpendicular to the plane in which the lifting platform extends. For example, the lifting platform may be arranged parallel to the base element. The extension directions of the first and second spindles may be parallel to each other, in particular perpendicular to the base element and the lifting platform.

[0018] The intermediate frame may have any shape. For example, the intermediate frame may include a plate to which the first and second drive devices are attached. However, the intermediate frame may also not include such a (common) plate, but rather include a first plate to which the first drive device (and optionally a further plurality of first drive devices) is attached, and a second plate to which the second drive device (and optionally a further plurality of second drive devices) is attached. Furthermore, the intermediate frame may not include any plates, but rather be composed of linkages, with the drive devices attached to rods of the linkages.

[0019] The first and second drive devices may each include a ball screw drive mechanism, in particular a shaft drive mechanism. The first and second drive devices may each be designed to include a drive mechanism (in particular a ball screw drive mechanism) that, with appropriate control and power supply, rotates around a spindle, where the spindle itself is stationary and does not rotate. In this way, vertical movement of the first drive device relative to the first spindle is achieved. Furthermore, vertical movement of the second spindle relative to the second drive device is also achieved in this way.

[0020] The lift platform may include the carrier device of the system.

[0021] 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 package, the top plate of which may represent the carrier device. The plate package may be attached to a plate-like element of the lifting platform, for example, using screws. In particular, the raw material may be applied onto the carrier plate. The fact that the lifting platform includes a carrier device may mean that the carrier device is rigidly connected to a further element of the lifting platform and / or forms an integral component with the further element of the lifting platform. In this case, the lifting device can be said to be two-stage, since it 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.

[0022] The lifting platform may include a further intermediate frame, where the lifting apparatus further includes the further lifting platform and at least one third spindle attached to the further lifting platform, and the further intermediate frame may include at least one third drive device for vertically moving the third spindle and the further lifting platform relative to the further intermediate frame.

[0023] The lifting device may therefore be three-stage or have further stages, thus four-stage, five-stage, etc. With regard to the attachment of the third spindle to the further lifting platform and with regard to the drive device, what has been said above with regard to the second spindle and the second drive device, respectively, may apply. The further lifting platform may comprise the carrier device of the system.

[0024] The first drive device and the second drive device may be controllable independently of each other.

[0025] In particular, the first and second drive devices may each include their own motor (e.g., servo motor) and / or actuator. Furthermore, the first and second drive devices may be independently controllable, for example, via corresponding gearboxes. For example, a common motor and a gearbox coupled to the motor and the first and second drive devices may be provided, such that only the first drive device is driven in the first gearbox position and only the second drive device is driven in the second gearbox position. Furthermore, a third gearbox position may be provided in which the first and second drive devices are driven simultaneously.

[0026] The first drive device may include a first motor and the second drive device may include a second motor.

[0027] Thus, the first and second drive devices may be controlled independently of one another by the control device of the lifting apparatus, including, for example, controlling one of the first and second drive devices while the other remains stationary, controlling the first and second drive devices in opposite directions, and / or controlling the first and second drive devices at different speeds.

[0028] The lifting apparatus may further include at least one further first spindle attached to the base element, and the intermediate frame may include at least one further first drive device for vertically moving the intermediate frame relative to the further first spindle and the base element.

[0029] With regard to the further first spindles and further first drive devices, the above aspects and details discussed with regard to the first spindles and first drive devices may apply. In particular, two, three or four first spindles and two, three or four first drive devices (associated with these spindles) may be provided.

[0030] The first drive device and the further first drive device may be controllable independently of each other.

[0031] In this way, the intermediate frame can for example be tilted (particularly in relation to the horizon) and / or horizontally oriented (hereinafter also referred to as "leveling"), and at the same time the carrier device can also be tilted and / or leveled.

[0032] The lifting apparatus may also include a control unit for independently controlling the first drive device and the second drive device.

[0033] The control unit may, for example, be or be included in the control unit of the system, and may include a microprocessor and a (volatile or non-volatile) memory in which a control program is stored and by which the respective drive device is controlled.

[0034] The lifting apparatus may further include at least one additional second spindle attached to the lifting platform, and the intermediate frame may include at least one additional second drive device for vertically moving the additional second spindle and the lifting platform relative to the intermediate frame.

[0035] With regard to the further second spindles and further second drive devices, the above aspects and details discussed with regard to the second spindles and second drive devices may apply. In particular, two, three or four second spindles and (associated with these spindles) two, three or four second drive devices may be provided.

[0036] The second drive device and the further second drive device may be controllable independently of each other.

[0037] In this way, the lifting platform can be tilted and / or leveled relative to a reference plane, for example, in particular the horizon, the coater, the laser optics or the floor of the process chamber, and at the same time the carrier device can be tilted and / or leveled.

[0038] 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. The lifting device may further include a device for detecting an 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 oriented horizontally.

[0039] By providing at least three second spindles, the lift platform can be oriented (leveled) horizontally, specifically with respect to a reference plane such as the horizon, a coater, a laser optics element, or the floor of a process chamber. Here, the lift platform can be tilted about at least two non-parallel axes, thereby enabling perfect leveling. The device for detecting the orientation can include, for example, a spirit level, an electronic spirit level, several triangulation lasers, and / or a corresponding sensor (including, for example, a suitable MEMS) for detecting, for example, the Earth's gravity. For example, if a sensor detects that the lift platform is not oriented horizontally, the corresponding second drive device can be controlled to align (i.e., level) the lift platform horizontally.

[0040] The device for detecting the orientation of the lift platform may include at least one linear encoder.

[0041] The linear encoder may, for example, allow for high precision (eg sub-micron precision) positioning of the lift platform relative to one or more guide rails. The linear encoder may be a so-called glass scale linear encoder.

[0042] The lifting device may further include at least one guide rail attached to the base element and at least one rail guide attached to the intermediate frame for guiding the intermediate frame during vertical movement relative to the first spindle and the base element.

[0043] The guide rail, together with the rail guide, can prevent tilting or twisting of the intermediate frame and / or the lifting platform, so that these two elements always remain horizontally aligned. This is particularly true when only the first spindle and / or the second spindle are provided. The rail guide can, for example, include one or more carriages. In particular, at least two rail guides can be provided for one or more guide rails.

[0044] The base element may include a base plate. In particular, the base element may be a base plate.

[0045] According to a second aspect, the invention relates to a system for additive manufacturing of three-dimensional workpieces, comprising a lifting device according to the first aspect.

[0046] All of the sub-aspects and aspects of the lifting device discussed above can be included in a corresponding manner in the lifting device of the system. The additive manufacturing system can be, for example, a system for selective laser sintering, selective laser melting, or selective electron beam melting. In addition to the lifting device, the system can have one or more of the above-mentioned features of corresponding known systems.

[0047] A system for additive manufacturing of three-dimensional workpieces may include, for example, a carrier device for applying powder in several layers so that a powder bed is formed. Furthermore, one or more powder application devices may be provided for applying powder, and if necessary, for applying powders of different materials. A separate powder application device may be provided for each material. A lifting device may be used to move the carrier device vertically downward so that the top powder layer always remains at the same height relative to the system's build chamber. Furthermore, the system may include one or more irradiation units. Each irradiation unit includes a beam source (particularly a laser beam source) and an optical system with one or more optical components for shaping and deflecting the beam (e.g., a beam expander, a focusing unit, a scanner device, an F-theta lens).

[0048] The invention will now be described with reference to the accompanying drawings. [Brief explanation of the drawings]

[0049] [Figure 1] FIG. 1 is a schematic side view of a system for additive manufacturing of three-dimensional workpieces including a lifting apparatus according to one embodiment of the present disclosure. [Figure 2] FIG. 2 is a perspective view of a lifting device according to a first embodiment of the present disclosure, including three first spindles and three second spindles, where section (a) represents the lifting device in a fully retracted position and section (b) represents the lifting device in a fully extended position. [Figure 3] FIG. 3 is a side view of the lifting device according to the first embodiment, with section (a) representing the fully retracted position and section (b) representing the fully extended position. [Figure 4] FIG. 4 is a perspective view of the lifting device according to the first embodiment, in a partially retracted position of the lifting device. [Figure 5]FIG. 5 is a perspective view of a lifting device according to a second embodiment of the present disclosure, including two first spindles and three second spindles, where section (a) represents the lifting device in a fully retracted position and section (b) represents the lifting device in a fully extended position. [Figure 6] FIG. 6 is a perspective view of a lifting device according to a third embodiment of the present disclosure, including one first spindle and three second spindles, where section (a) represents the lifting device in a fully retracted position and section (b) represents the lifting device in a fully extended position. DETAILED DESCRIPTION OF THE INVENTION

[0050] 1 shows a system 1 for additive manufacturing of a three-dimensional workpiece 2, where the system 1 includes a lifting apparatus 20 for a carrier device 5 of the system 1. Apart from the lifting apparatus 20, the system 1 is a conventional system for selective laser melting with known components. The selective laser melting techniques used by the system 1 are well known to those skilled in the art and will only be briefly described here with respect to selective laser melting in a powder bed 3.

[0051] First, a first layer of raw material powder is applied to a carrier 5 (also referred to as a carrier device 5) of the system 1, and one or more laser beams 7a, 7b are applied in a site-specific manner to solidify desired areas of the powder. This example shows the system 1 with two irradiation units, each including a laser 9a, 9b and an optical system 11a, 11b. Thus, the irradiation unit including the laser 9a and the optical system 11a is configured to emit the laser beam 7a and direct it to a desired location in the top powder layer of the powder bed 3. Furthermore, the irradiation unit including the laser 9b and the optical system 11b is configured to emit the laser beam 7b and direct it to a desired location in the top powder layer of the powder bed 3. The optical systems 11a, 11b each include components for beam shaping and beam deflection, such as lenses, deflection mirrors, scanner mirrors, etc.

[0052] All components of the system 1, in particular the lasers 9a, 9b, the scanner mirrors of the optical elements 11a, 11b, the movement of the carrier 5 using the lifting device 20, and the functioning of the powder application device 15 described below, are controlled by a control unit 13.

[0053] After the first powder layer has solidified as desired, another layer of powder is applied on top of the previous powder layer, and this top layer is irradiated and solidified again.

[0054] To maintain a constant distance between the top layer and the optical unit, it is possible to lower the carrier 5 and / or raise the optical unit during the build process (in 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 unsolidified powder can then be removed and optionally reused.

[0055] A horizontally movable application device 15 having suitable means for applying the powder in the form of a layer (e.g. at least one roller and / or at least one squeegee and / or at least one pusher and / or at least one storage container, etc.) is used to apply the powder.

[0056] A gas supply 17 supplies an inert gas to a build chamber 19 of the system 1, filling the interior of the build chamber 19 with an inert gas atmosphere. Additionally, a gas extraction system (not shown) may be provided that draws the inert gas out of the build chamber 19 in such a way that a gas flow is created through the build chamber (specifically across the powder bed 3).

[0057] The following describes the lifting device 20 in relation to several embodiments. In other words, the lifting device according to each of the following embodiments may be used as the lifting device 20 of the system 1 of FIG.

[0058] 2 shows a perspective view of a lifting device 20a according to a first embodiment of the present disclosure, with section (a) of FIG. 2 showing the lifting device 20a in a fully retracted position and section (b) showing the lifting device 20a in a fully extended position.

[0059] In the following, reference signs 20a, 20b and 20c are used for specific embodiments of the lifting apparatus 20. In other words, any of the embodiments described below may be used as the lifting apparatus 20 (e.g., in FIG. 1). Thus, reference sign 20 includes "sub-reference signs" 20a, 20b and 20c. The same applies to other reference signs used herein that are marked with lower case letters a, b and c, respectively. The lifting apparatus 20 is generally configured to move the carrier device 5 of the system vertically (i.e., along the z-direction).

[0060] For greater clarity, in the following figures, reference numerals are provided only for the representation of the extended state, it being understood that corresponding elements of the lifting device 20 in the stowed state are provided with the same reference numerals as the same elements in the extended state.

[0061] The lifting device 20a includes a base element in the form of a base plate 22 and three first spindles 24a, 24b, and 24c (collectively referred to as first spindles 24) attached to the base plate 22 using screws. When the terms "first," "second," and "third" are used herein, this is merely for the purpose of linguistic differentiation of individual elements. For example, the "first spindle" 24 on the lower level (also referred to as the lower stage) of the lifting device 20 is linguistically distinct from the "second spindle" 26 on the upper stage.

[0062] The plate-like base element 22 shown in FIG. 2 should not be understood as limiting, as the base element may also be a non-plate-like element, for example a frame structure to which one or more first spindles 24 are attached.

[0063] Spindles 24 and 26 are threaded rods and therefore have threads on their lateral surfaces. Spindle 24 is rigidly connected to base plate 22 unless rotatably mounted thereon. Spindles 24 each extend perpendicular to base plate 22 in the z-direction.

[0064] The lifting device 20a further includes a lifting platform 28 with three second spindles 26a, 26b, 26c (hereinafter collectively referred to as second spindles 26) attached thereto. In the illustrated embodiment, the lifting platform 28 includes a plate-like element. The second spindles 26 each extend downwardly from the lifting platform 28 along a z-direction perpendicular thereto. An intermediate level in the form of an intermediate frame 30 is provided between the base plate 22 and the lifting platform 28. In the illustrated embodiment, the intermediate frame 30 includes two horizontally extending plate elements and a connecting element positioned therebetween. The specific design of the intermediate frame 30 is ultimately at the discretion of those skilled in the art, and a wide variety of possible designs can be envisioned.

[0065] The intermediate frame 30 includes three first drive devices 32a, 32b, 32c associated with the respective first spindles 24a, 24b, 24c. More precisely, drive device 32a interacts with and / or constitutes a drive mechanism for spindle 24a. The same applies to drive devices 32b and 32c and the associated spindles 24b and 24c. The intermediate frame 30 further includes three second drive devices 34a (hidden in the figures and therefore not shown), 34b, 34c associated with the respective second spindles 26a, 26b, 26c. More precisely, drive device 34a interacts with and / or constitutes a drive mechanism for spindle 26a. The same applies to drive devices 34b and 34c and the associated spindles 26b and 26c.

[0066] The first drive devices 32 (collectively 32a, 32b, 32c) and the second drive devices 34 (collectively 34a, 34b, 34c) are each rigidly coupled to a further element of the intermediate frame 30. In the illustrated embodiment, the drive devices 32 and 34 are each mounted to a plate of the intermediate frame, with the associated spindles 24 and 26 being guided through associated holes in the respective plates of the intermediate frame 30.

[0067] The drive devices 32 and 34 each include a ball screw with a shaft drive mechanism, more precisely, the drive devices 32 and 34 are used to rotate a ball screw around the (fixed) spindles 24 and 26, respectively, to induce relative movement of the spindles and the drive devices due to the spindle threads.

[0068] In this manner, driving the drive device 32 causes vertical movement of the intermediate frame 30 relative to the first spindle 24 and the base plate 22. Furthermore, driving the second drive device 34 causes vertical movement of the second spindle 26 and the lifting platform 28. In this manner, both the movement of the first drive device 32 and the movement of the second drive device 34 cause movement of the lifting platform 28 relative to the base plate 22. In other words, both the movement of the first drive device 32 and the movement of the second drive device 34 can raise or lower the lifting platform 28 vertically.

[0069] In one embodiment, the carrier device 5 is directly attached to the lifting platform 28, for example screwed thereto. Alternatively, the lifting platform 28 may refer to the carrier device 5.

[0070] In other embodiments (not shown), the lifting apparatus has more than two stages and a further (third) drive device is provided on the lifting platform 28, which therefore represents a further intermediate frame. The third drive device itself drives an associated third spindle which is rigidly connected at its upper end to the further lifting platform. For example, the carrier device 5 may be attached to this lifting platform, which in this specific embodiment represents a three-stage lifting apparatus.

[0071] In one embodiment, the first drive device 32 is controllable independently of the second drive device 34. For example, a separate motor (particularly a servo motor) or actuator may be provided in each of the drive devices 32, 34, which can be individually controlled by a control unit (e.g., control unit 13). Thus, when only the first drive device 32 is operated and the second drive device 34 is not operated, only the “lower stage” (or “first stage”) of the lifting apparatus 20a moves. When only the second drive device 34 is operated and the first drive device 32 is not operated, only the “upper stage” (or “second stage”) of the lifting apparatus 20a moves. When both the first and second drive devices are moved simultaneously, both stages move simultaneously, thereby allowing the lifting platform 28 to move (i.e., raise and lower) faster relative to the base plate 22.

[0072] In a further embodiment, the first and / or second drive devices 32, 34 are individually controllable relative to one another. Thus, each of the individual drive devices 32a, 32b, 32c and / or each of the individual drive devices 34a, 34b, 34c can be individually controlled. In this manner, for example, the (e.g., non-horizontal) orientation of the lift platform 28 can be changed, and in particular, the lift platform 28 can be adjusted so that it is oriented horizontally (in particular, horizontally relative to the horizon or parallel to the base plate 22). In other words, the lift platform 28 can be leveled.

[0073] Due to the provision of three drive devices 24, 26 for each of the lower and upper stages, both the intermediate frame 30 and the lifting platform 28 can be tilted relative to two non-parallel axes. This makes it possible to completely level the intermediate frame 30 and the lifting platform 28. Leveling the lifting platform 28 means that the carrier device 5 connected to it is also leveled, which may be necessary in the additive manufacturing process, for example, to avoid any loss of quality.

[0074] For the purpose of determining the orientation of the lifting platform 28 and the associated orientation of the carrier device 5, the lifting apparatus 20 may include a device for detecting the orientation of the lifting platform 28. This may be, for example, a sensor arrangement provided in the lifting platform 28 or the carrier device 5. The sensor arrangement may, for example, include a triangulation laser system or an electronic split level, in particular one or more MEMS suitable for detecting the Earth's gravity. Furthermore, the device for detecting the orientation of the lifting platform 28 may include a linear encoder. The linear encoder may, for example, be provided in association with the guide rails described below, in particular capable of detecting the position of the rail guides relative to the respective guide rails.

[0075] The lifting device 20a further includes two guide rails 36a and 36b that are fixedly connected to the base plate 22 and extend perpendicular thereto and parallel to the spindles 24 and 26. The guide rails 36a and 36b guide associated rail guides 38a and 38b that are fixedly connected to the intermediate frame 30.

[0076] In this way, the intermediate frame 30 is guided during its vertical movement along the guide rails 36a, 36b, and twisting of the intermediate frame 30 is prevented. In the first embodiment shown, two rail guides, one above the other, are provided for each guide rail 36, resulting in better stability of the guided element (the intermediate frame 30), especially against tilting. The rail guides 38 may each be provided in the form of a carriage. However, the number of rail guides 38 per guide rail can be increased or decreased as desired, where a greater number of rail guides 38 may contribute to increased stability of the intermediate frame 30.

[0077] Section (a) of Figure 2 represents the fully retracted state of the lifting device 20a, where both the first and second stages are retracted and therefore the lifting platform 28 is at its lowest possible height. Section (b) of Figure 2 represents the fully extended state of the lifting device 20a, where both the first and second stages are extended and therefore the lifting platform 28 is at its highest possible height.

[0078] Figure 3 shows in side view (view direction along the y-axis of Figure 2) the lifting device 20a according to the first embodiment of Figure 2. The elements shown correspond to those of Figures 2(a) and 2(b).

[0079] 4 shows a second embodiment of the lifting device 20a according to the first embodiment in a perspective view similar to that of FIG. 2. In the illustration of FIG. 4, the lifting device 20a is shown in a partially retracted or partially extended state, with the lower (first) stage extended and the upper (second) stage retracted. Therefore, the first drive device 32 can be controlled independently of the second drive device 34, and thus the lifting device 20a can assume any desired state 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.

[0080] 5 shows a side view of a lifting apparatus 20b according to a second embodiment of the present disclosure, in which the lifting apparatus includes two first spindles 24a, 24b and three second spindles 26a, 26b, 26c. The lifting apparatus 20c has two first drive units 32a, 32b and three second drive units 34a, 34b, 26c associated with each of the spindles 24 and 26. Section (a) shows the lifting apparatus 20b in a fully retracted position, and section (b) shows the lifting apparatus 20b in a fully extended position.

[0081] In the second example embodiment of FIG. 5, only some elements are provided with reference numerals, whereby elements that clearly correspond to elements of the first example embodiment should be considered to be provided with the same reference numerals.

[0082] Apart from the number of first spindles 24 and first drive devices 32, the lifting apparatus 20b of the second example embodiment is identical to the lifting apparatus 20a of the first example embodiment. Therefore, the above description of the first example embodiment applies to the second example embodiment.

[0083] The advantage of the second embodiment over the first embodiment may be that the first spindle 24c and the first drive device 32c can be omitted. The guide rail 36 and the associated rail guide 38 ensure sufficient guidance and stabilization of the intermediate frame 30 during the movement of the lower stage. The provision of three second spindles 26 ensures sufficient possibilities for changing the alignment (leveling) of the lifting platform 28.

[0084] The advantage of the first embodiment over the second embodiment is that a larger load can be lifted (since the total load is distributed over the three first spindles 24). Furthermore, by using three first spindles 24, greater flexibility in alignment is created, since the intermediate frame 30 can already be aligned. In particular, in relation to the first embodiment, for example, the guide rail 36 and the associated rail guide 38 can be eliminated as well. This applies in principle to all embodiments mentioned herein.

[0085] 6 shows a side view of a lifting apparatus 20c according to a second embodiment of the present disclosure, in which the lifting apparatus includes one first spindle 24a and three second spindles 26a, 26b, and 26c. The lifting apparatus 20c has one first drive unit 32a and three second drive units 34a, 34b, and 34c associated with each of the spindles 24 and 26. Section (a) shows the lifting apparatus 20c in a fully retracted position, and section (b) shows the lifting apparatus 20c in a fully extended position.

[0086] In the third embodiment of FIG. 6, only some elements are provided with reference numerals, where elements that clearly correspond to elements of the first example embodiment should be considered to be provided with the same reference numerals.

[0087] Apart from the number and positions of the first spindles 24 and the first drive devices 32, the lifting apparatus 20c of the third embodiment is identical to the lifting apparatus 20a of the first embodiment and the lifting apparatus 20b of the second embodiment. Therefore, the above description of the first embodiment applies to the third embodiment.

[0088] An advantage of the third exemplary embodiment compared to the first and second embodiments may be that the number of first spindles 24 can be reduced to one, thereby saving costs and materials. The guide rails 36 and the associated rail guides 38 ensure sufficient guidance and stabilization of the intermediate frame 30 during movement of the lower stage. The provision of three second spindles 26 ensures sufficient possibilities for changing the orientation of the lifting platform 28.

[0089] 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, and thus embodiments with the following numbers of first spindles / second spindles are conceivable: 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. Of these, the 3 / 3, 2 / 3 and 1 / 3 arrangements may be particularly advantageous, as mentioned above.

[0090] Furthermore, multi-stage lifting devices are possible, having three or more stages, each stage being provided with at least one spindle with an associated drive device. For example, lifting devices with two, three, four, five, etc. stages are conceivable.

[0091] Using the above-described technique, it is possible to provide a lifting device that is compact when stored and allows a large distance between the base plate 22 and the lifting platform 28 when fully extended. In this way, the overall height of the system 1 remains relatively small, allowing large (specifically tall) workpieces to be manufactured in low-height production areas. Furthermore, the presented technique allows for precise and stable positioning, especially with regard to deformations of the lifting device 20. Furthermore, it ensures safe and stable guidance. Furthermore, it allows for alignment, especially leveling, of the lifting platform 28.

[0092] The two-stage lifting column "Multistage" described in the above embodiment (three-stage or multi-stage lifting columns are equally conceivable) can be used for positionally precise motorized height adjustment under heavy loads (e.g., 500-5000 kg) especially for build jobs, and for safe and stable guidance over the entire stroke in small overall dimensions. Shaft drives with rotating ball screws (servo drives) arranged adjacent to each other antiparallel in two drive directions can split the total stroke into two smaller individual strokes, thereby allowing for larger loads to be handled than would be possible without this split.

[0093] Depending on the number of drives and roller rail guides, different positioning accuracy results, which can be extremely relevant in the additive manufacturing sector with large build jobs.

Claims

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

2. 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 platform (28) further comprises an intermediate frame, and the lifting device (20, 20a, 20b, 20c) further comprises: - a further lifting platform; - at least one third spindle attached to said further lifting platform; 2. The lifting device (20, 20a, 20b, 20c) according to claim 1, wherein the further intermediate frame includes at least one third drive device for vertically moving the third spindle and the further lifting platform relative to the further intermediate frame.

4. 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) are controllable independently of each other.

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

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

7. 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) are controllable independently of each other.

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

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

10. 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) are controllable independently of each other.

11. at least three second spindles (26a, 26b, 26c) attached to the lifting platform, the intermediate frame (30) including at least three second drive devices (34a, 34b, 34c) for vertically moving the three second spindles (26a, 26b, 26c) and the lifting platform (28) relative to the intermediate frame (30); a device for detecting the orientation of said lifting platform (28); Including, the control unit (13) is configured to control the second drive devices (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. A lifting device (20, 20a, 20b, 20c) according to claims 8 and 10.

12. The lifting apparatus (20, 20a, 20b, 20c) of claim 11, wherein the device for detecting the orientation of the lifting platform (28) includes at least one linear encoder.

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

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

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