Lifting apparatus for a support device of an installation for additively manufacturing a three-dimensional workpiece

Abstract

The invention relates to a lifting apparatus for a support device of an installation for additively manufacturing a three-dimensional workpiece. The lifting apparatus comprises a base element, at least one first spindle secured to the base element, a lifting platform, and at least one second spindle secured to the lifting platform. The lifting apparatus also comprises at least one intermediate frame comprising at least one first drive device for vertically moving the intermediate frame in relation 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 in relation to the intermediate frame.

Description

[0001] Lifting device for a carrier device of a system for the additive manufacturing of a three-dimensional workpiece

[0002] The invention relates to a lifting device for a support device of a system for the additive manufacturing of a three-dimensional workpiece. In particular and without limitation, the additive manufacturing can involve a process of selective laser melting, selective laser sintering, or selective electron beam melting.

[0003] In additive (or generative) processes for producing three-dimensional workpieces, and in particular in generative layer-by-layer construction processes, it is known to apply an initially formless or shape-neutral molding compound of a raw material (e.g., a raw material powder) layer by layer onto a carrier (also referred to herein as a carrier device) and to solidify it by site-specific irradiation (e.g., by fusing or sintering) in order to ultimately obtain a workpiece of the desired shape. The irradiation can be carried out using electromagnetic radiation, for example, in the form of laser radiation, or by particle radiation, for example, in the form of electron beams. In an initial state, the molding compound can initially be in the form of granules, powder, or liquid molding compound and, as a result of the irradiation, can be solidified selectively or, in other words, site-specifically.The molding compound can comprise, for example, ceramic, metal, or plastic materials, as well as mixtures of these. One variant of additive layering processes involves so-called laser beam melting in a powder bed, in which metallic and / or ceramic raw material powder materials are solidified into three-dimensional workpieces under the irradiation of a laser beam.

[0004] To produce individual workpiece layers, it is also known to apply raw material powder in the form of a raw material powder layer to a carrier and to irradiate it selectively and in accordance with the geometry of the workpiece layer currently being produced. The laser radiation penetrates the raw material powder material and solidifies it, for example as a result of heating, which causes melting or sintering. Once a workpiece layer has solidified, a new layer of unprocessed raw material powder material is applied to the previously produced workpiece layer. Known coating arrangements or powder application devices can be used for this purpose. The now uppermost and still unprocessed raw material powder layer is then irradiated again. Consequently, the workpiece is built up successively layer by layer, with each layer defining a cross-sectional area and / or a contour of the workpiece.In this context, it is also known to use CAD or comparable workpiece data in order to produce the workpieces essentially automatically.

[0005] It is understood that all of the aspects explained above and the following aspects can also be provided within the scope of the present invention.

[0006] Before a new layer of raw material is applied, the support device onto which the first layer was applied is typically lowered vertically. This is done by a lifting device, which may have one or more motors, telescopic screw drives, actuators, pneumatic elements, etc., to move the support device vertically and then hold it at a predetermined height. The support device moves within a building cylinder, the side walls of which support the unconsolidated raw material during the production process. The support device thus forms the bottom wall of the building cylinder.

[0007] The size (especially the height) of additive manufacturing processes is continuously increasing. The resulting increase in build cylinder height also increases the overall height of the additive manufacturing system. This causes problems for end users in production halls with low ceiling heights. Therefore, there is a need for solutions that reduce system height.

[0008] One approach to solving this problem is the use of telescopic screw drives. However, these require a relatively large amount of installation space, are relatively complex to manufacture, and are therefore generally relatively expensive. Furthermore, the multi-stage nature of these telescopic screw drives can, in some situations, result in nonlinear deformation and / or varying stiffnesses of the respective screw stages under load.

[0009] It is therefore desirable to provide a lifting device that is compact, easy to manufacture, and inexpensive. Furthermore, a relatively low deformability of individual elements of the lifting device, or at least a precise predictability of the deformation of the elements of the lifting device, is desirable. The object of the invention is therefore to provide a lifting device that solves at least one of the problems described above or a related problem.

[0010] This object is achieved by a lifting device for a carrier device of a system for the additive manufacturing of a three-dimensional workpiece having the features of patent claim 1. The object is further achieved by a system according to claim 14. Further embodiments are specified in the subclaims.

[0011] According to a first aspect, the invention therefore relates to a lifting device for a support device of a system for the additive manufacturing of a three-dimensional workpiece. The lifting device comprises a base element, at least one first spindle fastened to the base element, a lifting platform, and at least one second spindle fastened to the lifting platform. The lifting device further comprises 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] The system may, in particular, be a system for selective laser melting or sintering, which, for example, has 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 support device for the manufactured workpiece.

[0013] The base element can be a structural base, in particular a structural fastening base. The base element can, for example, comprise a plate and / or a lattice structure. In particular, the base element can be designed to be placed on a floor or to be fastened to a floor and can thus enable a stationary fastening of the first spindle to a floor. If a plurality of first spindles are provided, the base element can enable a fixed relative positioning of the first spindles to one another. The base element can be a base plate. In particular, the base element can be a floor plate of the system. The base element can, for example, stand directly on a floor of a production hall or stand and / or be fastened to the floor with appropriate feet and / or damping elements.The base element can also be part of a production hall floor. The first spindle can, for example, be releasably attached to the base element, e.g., with screws, bolts, etc. Furthermore, the first spindle can also be permanently connected to the base element, e.g., welded. The first spindle can extend vertically upwards from the base element. In other words, the base element can be in the form of a substantially plate-shaped base plate and define an xy plane, with the first spindle extending perpendicularly thereto along the z direction.

[0014] The lifting platform can have any desired shape. The lifting platform can comprise a plate-shaped element and / or can be plate-shaped or at least substantially plate-shaped. In particular, the lifting platform can comprise a plate stack. The lifting platform can either be configured to serve as a support device or to encompass the support device, or it can be configured to serve as a further intermediate frame or to encompass a further intermediate frame.

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

[0016] The intermediate frame can have any desired shape. For example, the intermediate frame can comprise a plate to which the first and second drive devices are fastened. However, the intermediate frame can also not comprise such a (common) plate, but rather a first plate to which the first drive device (and optionally further first drive devices) is fastened, and a second plate to which the second drive device (and optionally further second drive devices) is fastened. Furthermore, the intermediate frame can also not comprise any plate(s) at all, but rather be composed of a linkage, wherein the drive devices are attached to rods of the linkage. The first drive device and the second drive device can each comprise a ball screw drive, in particular with a shaft drive.The first and second drive devices can be configured such that they each comprise a drive (in particular a ball screw drive) which, when appropriately controlled and supplied with power, rotates around the spindle, with the spindle itself being stationary and not rotating. In this way, a vertical movement of the first drive device relative to the first spindle is executed. Furthermore, a vertical movement of the second spindle relative to the second drive device is executed in this way.

[0017] The lifting platform can include the support structure of the system.

[0018] The lifting platform can, for example, comprise and / or represent the support device in the form of a support plate. For example, the lifting platform can comprise a plate pack, wherein an uppermost plate of the plate pack represents the support device. The plate pack can, for example, be fastened to a plate-shaped element of the lifting platform by means of screws. In particular, raw material can be applied to the support plate. The fact that the lifting platform comprises the support device can mean that the support device is rigidly connected to the other elements of the lifting platform and / or forms a one-piece component together with the other elements of the lifting platform. In this case, the lifting device can be said to be two-stage, since it comprises 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.

[0019] The lifting platform may comprise a further intermediate frame, wherein the lifting device further comprises a 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.

[0020] The lifting device can thus be three-stage or have additional stages, allowing it to be four-stage, five-stage, etc. Regarding the attachment of the third spindle to the additional lifting platform and the drive device, the above statements regarding the second spindles and the second drive devices apply. The additional lifting platform can comprise the support device of the system. The first drive device and the second drive device can be controlled independently of each other.

[0021] In particular, the first and second drive devices can each comprise their own motor (e.g., servomotor) and / or actuator. Furthermore, the first and second drive devices can be controlled independently of one another, for example, via a corresponding gear mechanism. For example, a common motor can be provided and a gear mechanism coupled to the motor and the first and second drive devices, which, in a first gear position, drives only the first drive device and, in a second gear position, drives only the second drive device. Furthermore, a third gear position can be provided, in which the first and second drive devices are driven simultaneously.

[0022] The first drive device may comprise a first motor and the second drive device may comprise a second motor.

[0023] Thus, the first drive device and the second drive device can be controlled separately from one another by a control device of the lifting device. The separate control includes, for example, controlling one of the first and second drive devices while the other drive device remains stationary, controlling the first and second drive devices in opposite directions, and / or controlling the first and second drive devices at different speeds.

[0024] 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 device for vertically moving the intermediate frame relative to the further first spindle and the base element.

[0025] With regard to the further first spindle and the further first drive device, the above-mentioned aspects and details discussed with regard to the first spindle and the first drive device may apply. In particular, two, three, or four first spindles and—associated with these—two, three, or four first drive devices may be provided. The first drive device and the further first drive device may be controllable independently of one another.

[0026] In this way, the intermediate frame can, for example, be tilted and / or aligned horizontally (hereinafter also referred to as leveled) (particularly with respect to the earth's horizon). At the same time, the support structure can be tilted and / or leveled.

[0027] The lifting device may further comprise a control unit for independently controlling the first drive device and the second drive device.

[0028] The control unit can, for example, be a control unit of the system or be included in 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 controls the respective drive devices.

[0029] The lifting device may further comprise at least one further second spindle attached to the lifting platform. The intermediate frame may comprise at least one further second drive device for vertically moving the further second spindle and the lifting platform relative to the intermediate frame.

[0030] With regard to the further second spindle and the further second drive device, the above-mentioned aspects and details discussed with regard to the second spindle and the second drive device may apply. In particular, two, three, or four second spindles and—associated with these—two, three, or four second drive devices may be provided.

[0031] The second drive device and the further second drive device can be controlled independently of one another.

[0032] In this way, the lifting platform can, for example, be tilted and / or leveled, in particular with respect to a reference plane, such as the earth's horizon, the coater, the laser optics, or the process chamber floor. At the same time, the support device can be tilted and / or leveled. The lifting device can comprise at least three second spindles fastened to the lifting platform, wherein the intermediate frame comprises at least three second drive devices for vertically moving the three second spindles and the lifting platform relative to the intermediate frame. Furthermore, the lifting device can comprise a device for detecting an orientation of the lifting platform. The control unit can be configured to control the second drive devices based on detection data from the device for detecting the orientation of the lifting platform such that the lifting platform is horizontally aligned.

[0033] By providing at least three second spindles, the lifting platform can be aligned (leveled) horizontally, in particular with respect to a reference plane, such as the earth's horizon, the coater, the laser optics, or the process chamber floor. The lifting platform can be tilted about at least two non-parallel axes, which can enable complete leveling. The device for detecting the alignment can comprise, for example, a spirit level, an electronic spirit level, several triangulation lasers, and / or corresponding sensors, for example for detecting the earth's gravitational force (including, for example, suitable MEMS). If the sensors detect, for example, that the lifting platform is not aligned horizontally, corresponding second drive devices can be controlled, which bring the lifting platform into a horizontal alignment (i.e., level it).

[0034] The device for detecting an orientation of the lifting platform may comprise at least one linear encoder.

[0035] The linear encoder can, for example, enable high-precision (e.g., sub-micrometer-accurate) positioning of the lifting platform relative to one or more guide rails. The linear encoder can be a so-called glass scale linear encoder.

[0036] The lifting device may further comprise at least one guide rail attached to the base member and at least one rail guide attached to the intermediate frame for guiding the intermediate frame during its vertical movement relative to the first spindle and the base member.

[0037] The guide rail in combination with the rail guide can prevent the intermediate frame and / or the lifting platform from tilting or twisting, ensuring that these two elements always remain horizontally aligned. This is particularly true if only a first spindle and / or a second spindle is provided. The rail guide can, for example, comprise one or more carriages. In particular, at least two rail guides can be provided for each of the one or more guide rails.

[0038] The base element may comprise a base plate. In particular, the base element may be a base plate.

[0039] According to a second aspect, the invention relates to a system for the additive production of a three-dimensional workpiece, comprising the lifting device of the first aspect.

[0040] All of the sub-aspects and details of the lifting device discussed above can be provided accordingly in the lifting device of the system. The system for additive manufacturing can, for example, be 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-described features of a corresponding known system.

[0041] The system for additive manufacturing of a three-dimensional workpiece comprises, for example, a carrier device for applying the powder in multiple layers to create a powder bed. Furthermore, one or more powder application devices can be provided for applying the powder and, if necessary, for applying powder of different materials. A separate powder application device can be provided for each material. The carrier device can be moved vertically downwards using the lifting device so that the uppermost powder layer always remains at the same height relative to a build chamber of the system. Furthermore, the system can comprise one or more irradiation units. The irradiation units each comprise a beam source (in particular a laser beam source) and an optics system with one or more optical components for shaping and deflecting the beam (e.g., beam expander, focusing unit, scanner device, F-theta lens).

[0042] The invention is explained below with reference to the accompanying figures. Figure 1 shows a schematic side view of a system for the additive manufacturing of a three-dimensional workpiece, comprising a lifting device according to an exemplary embodiment of the present disclosure;

[0043] Figure 2: a perspective view of a lifting device according to a first

[0044] Embodiment of the present disclosure, wherein the lifting device has three first spindles and three second spindles, wherein section (a) represents a fully retracted state and section (b) represents a fully extended state of the lifting device;

[0045] Figure 3: a side view of the lifting device according to the first embodiment, wherein section (a) represents the fully retracted state and section (b) represents the fully extended state;

[0046] Figure 4: a perspective view of the lifting device according to the first

[0047] Embodiment in a partially retracted state of the lifting device;

[0048] Figure 5: a side view of a lifting device according to a second embodiment of the present disclosure, wherein the lifting device has two first spindles and three second spindles, and wherein section (a) represents a fully retracted state and section (b) represents a fully extended state of the lifting device; and

[0049] Figure 6: a side view of a lifting device according to a third embodiment of the present disclosure, wherein the lifting device has a first spindle and three second spindles and wherein section (a) represents a fully retracted state and section (b) represents a fully extended state of the lifting device.

[0050] Figure 1 shows a system 1 for the additive manufacturing of a three-dimensional workpiece 2, 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 the known components. The selective laser melting technology used by the system 1 is well known to those skilled in the art and will only be briefly explained here using selective laser melting in the powder bed 3. First, a first layer of raw material powder is applied to a carrier 5 (also: carrier device 5) of the system 1 and irradiated in a location-specific manner by one or more laser beams 7a, 7b such that desired areas of the powder are solidified. The present example shows a system 1 with two irradiation units, each comprising a laser 9a, 9b and an optics 11a, 11b.Thus, the irradiation unit, which comprises the laser 9a and the optics 11a, is configured to emit the laser beam 7a and direct it to a desired location on the uppermost powder layer of the powder bed 3. Furthermore, the irradiation unit, which comprises the laser 9b and the optics 11b, is configured to emit the laser beam 7b and direct it to a desired location on the uppermost powder layer of the powder bed 3. The optics 11a, 11b each comprise components for beam shaping and beam deflection, such as lenses, deflection mirrors, scanner mirrors, etc.

[0051] All components of the system 1 are controlled by a control unit 13, in particular the lasers 9a, 9b, the scanner 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.

[0052] After the first layer of powder has solidified as desired, another layer of powder is applied on top of the previous powder layer and this top layer is again irradiated and solidified.

[0053] To maintain a constant distance between the top layer and the optical units, it is possible to lower the carrier 5 and / or raise the optical units (along a vertical direction defined herein as the z-direction) during the ongoing construction process. 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 reused if necessary.

[0054] For powder application, the horizontally movable powder application device 15 is used, which has suitable means for layer-by-layer powder application (for example, at least one roller and / or at least one doctor blade and / or at least one slider and / or at least one storage container, etc.).

[0055] A gas supply 17 supplies a build chamber 19 of system 1 with inert gas, so that an inert gas atmosphere prevails within the build chamber 19. Furthermore, a gas extraction system (not shown) can be provided, which extracts the inert gas from the build chamber 19, thus generating a gas flow through the build chamber 19 (in particular via the powder bed 3).

[0056] The lifting device 20 is explained in detail below using several exemplary embodiments. In other words, the lifting device according to each of the following exemplary embodiments can be used as the lifting device 20 of system 1 in Fig. 1.

[0057] Fig. 2 shows a perspective view of a lifting device 20a according to a first embodiment of the present disclosure. Section (a) of Fig. 2 shows a fully retracted state of the lifting device 20a, and section (b) shows a fully extended state thereof.

[0058] 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 the lifting device 20 (for example, in Fig. 1). The reference numeral 20 thus includes the "subreference numerals" 20a, 20b, and 20c. The same applies to the other reference numerals used herein, which bear the lowercase letters a, b, and c, respectively. The lifting device 20 is generally configured to move the support device 5 of the system vertically (i.e., along the z-direction).

[0059] For clarity, only the representations of the extended state are provided with reference numerals in the following figures. It is understood that the corresponding elements of the lifting device 20 in the retracted state bear the same reference numerals as the same elements in the extended state.

[0060] The lifting device 20a comprises a base element in the form of a base plate 22 and three first spindles 24a, 24b, 24c (hereinafter generally referred to as first spindles 24) fastened to the base plate 22 by means of screws. The use of the terms "first," "second," "third," etc., herein merely serves to linguistically distinguish the individual elements. For example, the "first spindles" 24 of the lower level of the lifting device 20 (or also: lower stage) are linguistically distinguished from the "second spindles" 26 of the upper stage.

[0061] The plate-shaped base element 22 shown in Fig. 2 is not to be understood as limiting and the base element can also be present as a non-plate-shaped element, for example as a frame construction to which the one or more first spindles 24 are fastened.

[0062] The spindles 24 and 26 are threaded rods and thus have a thread on their outer surface. The spindles 24 are firmly connected to the base plate 22 in that they are mounted in a non-rotatable manner. The spindles 24 each extend perpendicular to the base plate 22 in the z-direction.

[0063] The lifting device 20a further comprises a lifting platform 28 with three second spindles 26a, 26b, 26c attached thereto (hereinafter generally referred to as second spindles 26). In the illustrated embodiment, the lifting platform 28 comprises a plate-shaped element. The second spindles 26 each extend downward from the lifting platform 28 perpendicular to the latter, along the z-direction. An intermediate plane 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 comprises two horizontally extending plate elements and connecting elements located therebetween. Ultimately, the specific design of the intermediate frame 30 is at the discretion of the person skilled in the art, and a wide variety of design options are conceivable.

[0064] The intermediate frame 30 comprises three first drive devices 32a, 32b, 32c, which are assigned to the respective first spindles 24a, 24b, 24c. More precisely, the drive device 32a interacts with the spindle 24a or represents a drive for this spindle. The same applies to the drive devices 32b and 32c and the associated spindles 24b and 24c. The intermediate frame 30 further comprises three second drive devices 34a (hidden in the figure and therefore not shown), 34b, 34c, which are assigned to the respective second spindles 26a, 26b, 26c. More precisely, the drive device 34a interacts with the spindle 26a or represents a drive for this spindle. The same applies to the drive devices 34b and 34c and the associated spindles 26b and 26c.

[0065] The first drive devices 32 (collectively: 32a, 32b, 32c) and the second drive devices 34 (collectively: 34a, 34b, 34c) are each fixedly connected to the other elements of the intermediate frame 30. In the illustrated embodiment, the drive devices 32 and 34 are each attached to a plate of the intermediate frame, with the associated spindles 24 and 26 being guided through associated holes in the respective plate of the intermediate frame 30. The drive devices 32 and 34 each comprise a ball screw with a shaft drive. More precisely, with the help of the drive units 32 and 34, a ball screw is rotated around the (stationary) spindle 24 and 26, respectively, which, due to the thread of the spindle, leads to a relative movement between the spindle and the drive device.

[0066] In this way, a drive of the drive devices 32 causes a vertical movement of the intermediate frame 30 relative to the first spindles 24 and the base plate 22. Furthermore, a drive of the second drive devices 34 causes a vertical movement of the second spindles 26 and the lifting platform 28. In this way, both the movement of the first drive devices 32 and the movement of the second drive devices 34 cause a movement of the lifting platform 28 relative to the base plate 22. In other words, a vertical raising or lowering of the lifting platform 28 can be caused by both the movement of the first drive devices 32 and the second drive devices 34.

[0067] In one embodiment, the support device 5 is mounted directly on the lifting platform 28, for example, screwed thereto. Alternatively, the lifting platform 28 can represent the support device 5.

[0068] In other embodiments (not shown), the lifting device has more than two stages, and additional (third) drive devices are provided on the lifting platform 28, which thus represents a further intermediate frame. The third drive devices, in turn, drive associated third spindles, which are firmly connected at their upper end to another lifting platform. For example, the support device 5 can be attached to this lifting platform, which in this specific embodiment represents a three-stage lifting device.

[0069] In one embodiment, the first drive devices 32 can be controlled independently of the second drive devices 34. For example, each of the drive devices 32, 34 can be provided with its own motor (in particular a servo motor) or actuator, which can be controlled individually by a control unit (for example, by the control unit 13). Thus, if only the first drive devices 32 are operated, but not the second drive devices 34, only the "lower stage" (or "first stage") of the lifting device 20a moves. If only the second drive devices 34 are operated, but not the first drive devices 32, only the "upper stage" (or "second stage") of the lifting device 20a moves.If both the first and second drive devices are moved simultaneously, both stages move simultaneously and the lifting platform 28 can thus be moved (ie raised or lowered) more quickly relative to the base plate 22.

[0070] In a further embodiment, the first and / or second drive devices 32, 34 can be individually controlled. Thus, each of the drive devices 32a, 32b, 32c and / or each of the drive devices 34a, 34b, 34c can be individually controlled. In this way, for example, a (for example, non-horizontal) orientation of the lifting platform 28 can be changed and, in particular, adjusted so that the lifting platform 28 is aligned horizontally (in particular horizontally with respect to the earth's horizon or parallel to the base plate 22). In other words, the lifting platform 28 can be leveled.

[0071] Since three drive devices 24, 26 are provided for 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 allows for complete leveling of the intermediate frame 30 and the lifting platform 28. Leveling the lifting platform 28 also means that the associated support device 5 is leveled, which may be necessary, for example, in the additive manufacturing process to avoid quality losses.

[0072] For the purpose of aligning the lifting platform 28 and the associated alignment of the support device 5, the lifting device 20 can have a device for detecting an alignment of the lifting platform 28. This can be, for example, a sensor arrangement provided in the lifting platform 28 or the support device 5. The sensor arrangement can, for example, comprise a triangulation laser system or an electronic spirit level, in particular one or more MEMS, which are suitable for detecting the earth's gravitational force. Furthermore, the device for detecting the alignment of the lifting platform 28 can comprise a linear encoder. Linear encoders can, for example, be provided in conjunction with the guide rails described below and, in particular, detect a position of a rail guide in relation to the respective guide rail.

[0073] The lifting device 20a further comprises two guide rails 36a and 36b. The guide rails 36a, 36b are fixedly connected to the base plate 22 and extend perpendicular to it, parallel to the spindles 24 and 26. The guide rails 36a, 36b guide associated rail guides 38a and 38b, which are fixedly connected to the intermediate frame 30. 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 are provided one above the other for each guide rail 36, which results in better stability of the guided element (the intermediate frame 30), particularly with respect to tilting. The rail guides 38 can 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, whereby a larger number of rail guides 38 can contribute to increased stability of the intermediate frame 30.

[0074] Section (a) of Fig. 2 illustrates a fully retracted state of the lifting device 20a, in which both the first stage and the second stage are retracted, and the lifting platform 28 is thus at the lowest possible height. Section (b) of Fig. 2 illustrates a fully extended state of the lifting device 20a, in which both the first stage and the second stage are extended, and the lifting platform 28 is thus at the greatest possible height.

[0075] Fig. 3 shows the lifting device 20a according to the first embodiment of Fig. 2 in a side view (viewed along the y-axis of Fig. 2). The elements shown correspond to those of Figs. 2(a) and 2(b).

[0076] Fig. 4 shows the lifting device 20a according to the first embodiment of Fig. 2 in a perspective view, similar to the view of Fig. 2. The illustration in Fig. 4 shows a partially retracted or partially extended state of the lifting device 20a. Here, the lower (first) stage is extended and the upper (second) stage is retracted. The first drive devices 32 can thus be controlled independently of the second drive devices 34, so that any desired states of the lifting device 20a can be assumed with regard to a position of the intermediate frame 30 in relation to the base plate 22 and a position of the lifting platform 28 in relation to the intermediate frame 30.

[0077] Fig. 5 shows a side view of a lifting device 20b according to a second embodiment of the present disclosure, wherein the lifting device has two first spindles 24a, 24b and three second spindles 26a, 26b, 26c. Associated with these spindles 24 and 26, the lifting device 20c has two first drive units 32a, 32b and three second drive units 34a, 34b, 23c. It shows section

[0078] (a) a fully retracted state of the lifting device 20b and section

[0079] (b) a fully extended state of the lifting device 20b.

[0080] In the second embodiment of Fig. 5, only some elements are provided with reference numerals, wherein the elements which clearly correspond to those of the first embodiment are to be considered as provided with the same reference numerals.

[0081] Apart from the number of first spindles 24 and first drive devices 32, the lifting device 20b of the second embodiment is identical to the lifting device 20a of the first embodiment. The above description of the first embodiment applies accordingly to the second embodiment.

[0082] An advantage of the second embodiment over the first embodiment may be that a first spindle 24c and a first drive device 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 rail guides 38. A sufficient possibility of changing the orientation of the lifting platform 28 (leveling) is ensured by the provision of three second spindles 26.

[0083] An advantage of the first embodiment over the second embodiment may be that heavier loads can be lifted (since the total load is distributed across three first spindles 24). Furthermore, the intermediate frame 30 can already be aligned using the three first spindles 24, which provides greater flexibility in alignment. Particularly in connection with the first embodiment, the guide rails 36 and the associated rail guides 38 can also be omitted. This applies in principle to all embodiments mentioned herein.

[0084] Fig. 6 shows a side view of a lifting device 20c according to a second embodiment of the present disclosure, wherein the lifting device has a first spindle 24a and three second spindles 26a, 26b, 26c. Associated with these spindles 24 and 26, the lifting device 20c has a first drive unit 32a and three second drive units 34a, 34b, 34c, respectively. Section (a) shows a fully retracted state of the lifting device 20c, and section (b) shows a fully extended state of the lifting device 20c. In the third embodiment of Fig. 6, only a few elements are provided with reference numerals, wherein the elements that clearly correspond to those of the first embodiment are to be considered as provided with the same reference numerals.

[0085] Apart from the number and arrangement position of the first spindles 24 and the first drive devices 32, the lifting device 20c of the third embodiment is identical to the lifting device 20a of the first embodiment and the lifting device 20b of the second embodiment. The above description of the first embodiment applies accordingly to the third embodiment.

[0086] An 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 rail guides 38. A sufficient possibility of changing the orientation of the lifting platform 28 is ensured by the provision of three second spindles 26.

[0087] It should be noted that the number of first spindles 24 and the number of second spindles 26 is ultimately arbitrary in each case and thus, for example, embodiments are conceivable which have the following number of first spindles / second spindles: 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 constellations 3 / 3, 2 / 3 and 1 / 3 can be particularly advantageous, as described above.

[0088] Furthermore, multi-stage lifting devices are possible, which have more than two stages, with at least one spindle and associated drive device being provided for each stage. For example, two-stage, three-stage, four-stage, five-stage, etc. lifting devices are conceivable.

[0089] The technology described above can provide a lifting device that is compact when retracted and allows a large distance between base plate 22 and lifting platform 28 when fully extended. In this way, large (especially tall) workpieces can be manufactured even in low production halls, since the overall height of system 1 remains relatively low. Furthermore, the presented technology can enable precise and stable positioning, particularly with regard to deformations of the lifting device 20. Furthermore, safe and stable guidance can be ensured. Furthermore, it may be possible to enable alignment and, in particular, leveling of the lifting platform 28.

[0090] A 2-stage "multistage" lifting column as described in the above examples (a 3-stage or multi-stage lifting column is also conceivable) is used for precise electrical height adjustment under heavy loads (e.g., 500-5000 kg), particularly for a construction job, and for safe, stable guidance over the entire stroke with small external dimensions. The shaft drives (servo drives) with recirculating ball screws, arranged anti-parallel next to each other in two actuation directions, can accommodate a higher load than without this division by dividing the total stroke into two small individual strokes.

[0091] Depending on the number of drives and the number of roller rail guides, different positioning accuracies result. This can be particularly relevant in the additive manufacturing sector with large build jobs.

Claims

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

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

3. 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: a further lifting platform; and at least one third spindle attached to the further lifting platform, wherein the further intermediate frame comprises at least one third drive device for vertically moving the third spindle and the further lifting platform relative to the further intermediate frame.

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

5. Lifting device (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. Lifting device (20, 20a, 20b, 20c) according to one of claims 1 to 5, further comprising: at least one further first spindle (24a, 24b, 24c) attached to the base element (22), wherein 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 spindle (24a, 24b, 24c) and the base element (22).

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

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

9. 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), wherein the intermediate frame (30) comprises at least one further second drive device (34a, 34b, 34c) for vertically moving the further second spindle (26a, 26b, 26c) and the lifting platform (28) relative to the intermediate frame (30).

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

11. Lifting device (20, 20a, 20b, 20c) according to claims 8 and 10, comprising: at least three second spindles (26a, 26b, 26c) attached to the lifting platform, wherein the intermediate frame (30) comprises 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); and a device for detecting an orientation of the lifting platform (28), wherein the control unit (13) is configured to, based on detection data from the device for detecting the orientation of the lifting platform (28), to control the drive devices (34a, 34b, 34c) so that the lifting platform (28) is horizontally aligned.

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

13. 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); and at least one rail guide (38a, 38b) attached to the intermediate frame (30), for guiding the intermediate frame (30) during its vertical movement relative to the first spindle (24a, 24b, 24c) and the base element (22).

14. Lifting device (20, 20a, 20b, 20c) according to one of claims 1 to 13, wherein the base element (22) comprises a base plate (22).

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

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