Method and apparatus for additive manufacturing

Abstract

A method for additive manufacturing, in which parts (10, 42, 43, 44, 45) are produced layer by layer by a starting material (4) that is hardened by an energy beam (8, 41, 58) irradiated by an energy beam irradiating means (9, 22, 31, 38, 39, 55, 59, 61) while the starting material (4) is supported by a base surface (3, 15, 30, 36, 52) arranged on a base element (2, 16, 29, 35, 51), and the energy beam is A method, wherein a base element (2, 16, 29, 35, 51) is moved with a rotational component having a base element rotation axis while a gee beam (8, 41, 58) impacts the starting material (4), and the starting material (4) is held on a base surface (3, 15, 30, 36, 52) by centrifugal acceleration generated via the rotational component, and a rotational motion is provided for at least a portion of the energy beam application means (9, 22, 31, 38, 39, 55, 59, 61). Similarly, an apparatus for additive manufacturing, wherein the starting material (4) is held on a base surface (3, 15, 30, 36, 52) by centrifugal acceleration, and at least one energy beam rotation axis (46) is provided for rotating at least a portion of the energy beam application means (9, 22, 31, 38, 39, 55, 59, 61).

Description

[Technical field]

[0001] The invention relates to a method for additive manufacturing according to the preamble of claim 1 and to an apparatus for additive manufacturing according to the preamble of claim 16. [Background technology]

[0002] Additive manufacturing or additive manufacturing in the sense of the present invention means the layer-by-layer production of components from starting materials that are present, for example, in powder form, under irradiation with an energy beam, for example a laser beam or an electron beam. For example, selective laser melting, also known as laser powder bed melting (LPBF), selective laser sintering (for example SLS) or electron beam melting are known from the prior art. By layer-by-layer construction, complex internal and external structures can be realized in three-dimensional components, such as cooling channels or support structures. Additive manufacturing offers high possibilities for realizing digitally controlled process chains in the sense of Industry 4.0, especially when using laser beams. In this way, subsequent customer coupling points can be provided and standardized semi-finished products can be used. Fields of application are, inter alia, the automotive sector, aerospace, medical technology, tool and mechanical engineering.

[0003] Since the development of the LPBF process in 1999, additive manufacturing has been established as a technique for the rapid production of small to medium series, primarily of prototypes or specific parts. Since then, additive manufacturing has led to a paradigm shift in the growing field from primarily subtractive process chains to generative processes. However, so far additive manufacturing has been used relatively little in the manufacture of mass-produced parts, as established processes are usually more economical.

[0004] The low economic efficiency of additive manufacturing processes is often due to the relatively low build rates and the associated high part costs. Furthermore, additively manufactured surfaces often require post-processing. Further problems can arise due to residual porosity in the parts as well as the loss of expensive powder-like substrates due to low process efficiency.

[0005] To date, additive manufacturing has been dominated by machine kinematics using a Cartesian coordinate system, typically employing a powder bed and two-axis beam guidance for the energy beam that is lowered after a layer of a part is completed.

[0006] In some process variants of additive production, a gas flow is used, in particular a protective or inert gas, which prevents oxygen from entering the starting materials.

[0007] EP 3 357 606 A1 describes an apparatus for selective laser melting, in which a laser beam is guided in its processing path over a powder bed so that particles generated during processing are not blown into the unprocessed powder bed by a gas flow directed at the part. In the example shown, the direction of the gas flow is constant and the direction of the processing path can be changed by a scanner unit of the laser device.

[0008] DE 102018109737 A1 discloses a method and an apparatus of the type mentioned at the outset, in which a laser is used for selective sintering of powder material in a build chamber, which is designed in the shape of a ring and rotates relative to the powder deposition system and the laser. The material application takes place in a build direction that is essentially parallel to the base element rotation axis. In this way, a number of parts distributed in a ring can be additively produced, and part layers can be sintered one after the other on different parts with the same laser scanner, while new powder can be applied or peeled off on another part at the same time. In this way, a higher throughput is possible.

[0009] A similar disclosure can be found in EP 2 983 896 B1, according to which a carrier for the workpieces to be produced and a powder distributor for generating a powder bed are provided in a process chamber of a system for selective laser melting, where the powder distributor and the shaft support are rotatably arranged. The cup-shaped structure of the carrier is such that when the carrier rotates, the cylindrical wall rotates together with the bottom, thereby avoiding relative movements between the wall of the process chamber, where the powder bed is produced, and the rotating bottom of the process chamber, which serves as a base for the workpieces to be produced.

[0010] From CN206839165U a 3D printing process is known, by means of which cylinders or hollow cylinders with large diameters, for example 2 m or more, can be produced. For this purpose, a 3D printer is used which is designed with an overall cylindrical shape, the main building direction being arranged parallel to the cylinder axis.

[0011] CN108015278B discloses a 3D printing device that distributes powder with a cylindrical powder distributor having a structure that rotates around the z-axis on a base perpendicular to the z-axis, with the structure of the part to be printed being parallel to the z-axis.

[0012] DE 102010041284 A1 discloses a process for selective laser sintering, in which powder application is carried out by a rotating powder distributor, the rotation axis of which is arranged inside a closed annular cross-section of the part to be produced and perpendicular to the surface of the powder bed. At least during the first linear energy input, the laser beam should be guided along the curved contour of the part so that this contour can be step-free reproduced by the sintered material.

[0013] From US 2020 / 0180224 A1, a method and an apparatus for three-dimensional printing are known, which comprises a frame rotating around an axis with a base surface on which a three-dimensional object is built up with a powder layer as starting material. The rotational movement of the frame exerts a sufficient centrifugal force on the powder layer deposited on the base surface, so that the powder layer is continuously held by the base surface and an energy beam is applied for 3D printing. The powder can be sprayed using a pivot arm that is supported on a central rotating shaft of the frame but does not rotate. The beam source is fixed to a cardan ring radially spaced from the rotating shaft of the frame so that it can rotate in any direction.

[0014] Methods and devices for 3D printing using a rotating base surface and centrifugal forces acting on the powder are known from DE 4308189 C1 and DE 102018019 A1. Summary of the Invention

[0015] The present invention is based on the technical problem of providing a method and an apparatus for additive manufacturing, which has an alternative kinematics to the prior art and which offers improved options for influencing the starting materials and the process control.

[0016] Regarding the method, the technical problem is solved with the characterizing features of claim 1. Advantageous embodiments arise from the dependent method claims.

[0017] Thus, in a method for additive manufacturing, a part is produced in layers by starting material which is hardened or solidified by an energy beam irradiated by an energy beam irradiation means while the starting material is supported by a base surface arranged on a base element, and while the energy beam impinges on the starting material, the base element is moved with a rotational component having a base element rotation axis, and the starting material is held on the base surface by centrifugal acceleration generated via the rotational component, a rotational movement is provided to at least a part of the energy beam irradiation means.

[0018] According to the method according to the invention, the starting material is not placed on the base surface by the gravitational acceleration, but remains attached on the base surface by the centrifugal acceleration. The rotational component of the movement has an appropriate angular velocity, which prevents the starting material from slipping or falling off the base surface, for example based on the gravitational acceleration. In this way, a dynamics for additive manufacturing is given, which provides additional options for influencing the state of the starting material or various parameters of the manufacturing process. It is proposed for the first time to provide a rotational movement for at least a part of the energy beam application means. This means that not only the base element but also the energy beam can be rotated during the additive manufacturing process, which gives additional options for setting or changing the relative speed between the energy beam and the starting material to be processed. The rotational movement of at least a part of the energy beam application means is guided in such a way that the energy beam itself rotates in the base element, so that the part of the energy beam extending between the energy beam application means and the starting material has an energy beam rotation axis aligned perpendicular to at least one component of the propagation direction of the energy beam.

[0019] The energy beam application means may comprise optical elements such as lenses, mirrors and / or light guides.

[0020] It may be particularly advantageous to carry out the method according to the invention in such a way that the rotational movement for the energy beam application means or for at least a part of the energy beam application means is carried out with the energy beam rotation axis parallel to the base element rotation axis, in this way the energy beam can be used without restriction in the full angular range of 360° of the central angle of rotation in the circumferential direction of the base element.

[0021] It is particularly advantageous if the base element rotation axis and the energy beam rotation axis are coaxial or can be coaxially aligned with one another. Coaxial alignment of the rotation axes means, for example, that in each angular position of the rotating energy beam application means or of at least a portion of the rotation of the energy beam application means, the radial distance of the exit point of the energy beam to the base surface, which is assumed to be cylindrical, remains the same.

[0022] The method according to the invention can also be implemented by varying the relative speed of the impact point of the energy beam on the surface of the base or starting material relative to the base surface or starting material during additive manufacturing, resulting in additional parameters being added to the manufacturing process.

[0023] Additionally, methods according to the present invention can be implemented to vary the intensity of the energy beam during additive manufacturing.

[0024] The variation of the relative speed and intensity of the energy beam can be performed in time and / or in space, such that different relative speeds and / or intensities can be provided for different coordinates in the axial direction, i.e., parallel to the axis of rotation of the base element, and / or for different layers in a layered build-up of the part.

[0025] The method according to the invention can be carried out with different angular velocities of the rotational movement of the energy beam application means or of at least a part of the energy beam application means and the rotational movement of the base element. In this way, the relative velocity of the energy beam with respect to the starting material can be changed at the point where the energy beam impacts the source material without having to change the rotational velocity of the base element. This is advantageous because the base element together with the starting material has a much larger moment of inertia than the energy beam application means.

[0026] Furthermore, the method according to the invention provides that the direction of rotation of the rotational movement of the energy beam application means or at least a part of the energy beam application means and the direction of rotational movement of the base element are opposite to each other. In this way, a relative speed between the energy beam and the starting material is achieved, which clearly exceeds the peripheral speed of the starting material rotating with the base element. Of course, the direction of rotation of the rotational movement of the energy beam application means or at least a part of the energy beam application means and the direction of rotational movement of the base element can be the same. The direction of rotation of the rotational movement of the energy beam application means or at least a part of the energy beam application means can also be changed with respect to the direction of rotational movement of the base element, so that a wider range of relative speeds between the energy beam and the starting material can be used.

[0027] The method according to the invention can also be implemented in such a way that the angular speed of the rotational movement of the energy beam application means or at least a part of the energy beam application means is changed during the additive manufacturing. For example, this angular speed can be adapted to a change, for example an increase, in the layer thickness of the starting material. Thus, as already mentioned, not only can the relative speed between the impact point of the energy beam and the starting material be changed as required, but in this way it can also be ensured that the relative speed remains as constant as possible even with an increase in the layer thickness of the starting material, without the need to change the angular speed of the base element.

[0028] Via the angular velocity of the rotational movement of the base element, it is possible to influence, for example, the pore formation, the energy input or, if gas, for example protective gas, is used, the gas flow. It is also possible to provide different alignments of the rotation axes of the rotating components, for example parallel or perpendicular to the direction of the gravitational acceleration or any other alignment. In the course of the method, the alignment of the rotation axes can also be changed.

[0029] For example, if the starting material is in powder form, the dynamics of the powder can be influenced by changing the angular velocity. Increasing the rotation speed increases the pressing force of the powder particles against each other in the powder bed and can reduce denudation, i.e. the undesired removal of powder particles or entire layers by gas flows or other influences, or the scattering (spattering) of powder particles. The centrifugal acceleration can also affect the size and number of pores and gas inclusions in the part. Influencing by centrifugal acceleration is also possible for other forms of starting material, for example viscous starting materials.

[0030] The method according to the invention can be carried out in such a way that the magnitude of the centrifugal acceleration acting on the starting material corresponds at least to the magnitude of the gravitational acceleration. In this case, it is also possible to carry out the method according to the invention when the base element rotation axis of the rotating component is aligned perpendicular to the gravitational acceleration. The centrifugal acceleration can also be several times the gravitational acceleration, for example a multiple of the gravitational acceleration, for example at least 15 m / s 2 , at least 20m / s 2 Or at least 50m / s 2 Or at least 100 m / s 2 In terms of the absolute value of the gravitational acceleration, the gravitational acceleration may be at least 1.5 times, and more preferably at least twice, the acceleration of gravity. In particular, it may be advantageous to adjust the centrifugal acceleration in a targeted manner.

[0031] Furthermore, it may be advantageous to change the centrifugal acceleration during a manufacturing process, even for the production of the same part, so that the process flow can be influenced in completely new ways. For example, by changing the centrifugal acceleration, the density of the starting material can be influenced, which in turn can affect the structure of the part to be produced. For example, due to the higher pressure in the starting material, gas inclusions can be displaced in the direction of the rotation axis, which can reduce the number of porosity in the part.

[0032] Furthermore, the process according to the invention can be carried out so that the layer is composed of at least one main component whose local surface normal is parallel or non-parallel to the centrifugal acceleration. The starting material usually assumes an inner surface with a local normal oriented non-parallel to the centrifugal acceleration. In a corresponding manner, the component layers produced in the starting material bed can be aligned by hardening, for example by welding, sintering or after melting. In this way, the sequence of the stacked component layers usually extends radially in the direction of the base element rotation axis.

[0033] The method according to the invention can also be carried out in such a way that in the same manufacturing step at least two parts are built on the same base element, said parts being spaced apart from one another in the circumferential and / or axial direction.

[0034] Furthermore, the method according to the invention can also be implemented in such a way that at least one part that is circumferentially closed in the base surface is built up on the base element. Such a part can be, for example, annular, tubular, hollow cylindrical in shape. Several circumferentially closed or connected parts can be produced simultaneously or successively, axially spaced apart from one another. The part or at least one of the parts can be rotationally symmetrical.

[0035] Furthermore, the method according to the invention can also be implemented in such a way that the base element is hollow cylindrical in at least some areas, the central longitudinal axis of the hollow cylindrical shape being used as the base element rotation axis for the rotational components.

[0036] However, the base element may also have structures in its base surface which differ from a hollow cylindrical shape or which serve to determine the shape of the component to be manufactured, such as recesses, chambers or webs.

[0037] The movement of the base element may also differ from a pure rotation: the rotation may be combined with other movement components, such as, for example, a swing movement about a swing axis perpendicular to the axis of rotation of the base element or (one or more) translational movements, thus offering the possibility of further influencing the starting material to be hardened.

[0038] With regard to an apparatus for additive manufacturing comprising a base element having a base surface for receiving a starting material, an energy beam application means provided for applying an energy beam in the direction of the base surface, and a base element drive means for moving the base element with a rotational component having a base element rotation axis, the base surface extending along a direction parallel to the base element rotation axis, the technical problem being solved by at least one energy beam rotation axis for rotating at least a part of the energy beam application means.

[0039] Advantageous developments are given by the dependent claims.

[0040] The extension of the base surface along a direction parallel to the base element rotation axis does not mean that the base surface must have a plane vector parallel to the base element rotation axis, i.e. that it extends parallel to the base element rotation axis. As seen in the direction of the base element rotation axis, the base surface may also be at least partially inclined. As will be explained further below, the base surface may therefore differ from a hollow cylindrical shape.

[0041] The energy beam application means may for example comprise beam shaping means or beam guiding means such as one or more radiation guiding fibers, mirrors or other optical elements, or a scanner device etc. The energy beam may be a laser beam or may be any other energy beam suitable for curing the starting material, such as for example a beam formed by an electron beam or a UV beam, especially if the starting material is a fluid.

[0042] The base element drive means is arranged to rotate the base element at a sufficiently high angular velocity to hold the starting material on the base surface based on a centrifugal acceleration acting on the starting material, the magnitude of the centrifugal acceleration acting on the starting material preferably corresponding to at least the magnitude of the acceleration of gravity.

[0043] The device according to the invention may also have at least one axis of movement in addition to the axis of rotation of the energy beam for moving at least a part of the energy beam application means. The part of the energy beam application means which moves relative to the rotation or additional axis of movement can for example be a beam output to which the energy beam is supplied via suitable means, such as mirrors, beam guide fibers and / or other optical elements.

[0044] At least one of the additional axes of movement can be a swing axis. It is therefore possible for the energy beam application means or its movable part to rotate or swing in the same direction and with the same angular velocity as the base element. For layer building, the energy beam can be guided on the starting material by suitable means, such as a scanner device or other beam deflection means, which are part of the energy beam application means or are provided separately. However, the rotation or swing movement of the energy beam application means or its movable part does not necessarily have to coincide with the angular velocity of the rotation of the base element. It is also conceivable to temporarily stop the rotation or swing of the energy application means or its movable part or to use an angular velocity different from the angular velocity of the base element.

[0045] If the energy beam application means or its movable parts do not rotate or swing or their angular speed differs from that of the base element, it is possible to coordinate the irradiation with the rotation of the base element, for example by always activating the energy beam or releasing the irradiation of the starting material or the part when the area of ​​the starting material to be processed or the already partially manufactured part reaches the appropriate position. In this case, a pulsed irradiation is performed, i.e. the irradiation is interrupted once or several times during one revolution of the base element relative to the energy application means. The irradiation time can be calculated, for example, from the rotation speed of the base element, the current inner diameter of the starting material, for example the powder bed, and the diameter of the impinging energy beam. Furthermore, the time of starting and ending the irradiation of the starting material or part can be synchronized with the angular position of the base element. In the case of parts closed in the circumferential direction of the rotational movement of the base surface, the beam action can also be performed continuously in the course of at least one revolution of the base element.

[0046] The device according to the invention can also be designed such that at least one of the additional axes of movement is a translational axis, in particular a linear or straight axis. Such a translational axis may be provided in addition to at least one rotational axis for the energy application means or its movable part. The at least one translational axis may in particular be provided for a movement parallel and / or perpendicular to the base element rotation axis. A translational axis having at least one component parallel to the base element rotation axis may be configured such that at least a part of the energy application means or its movable part can move into or out of the base element.

[0047] The rotation, swing and translation axes can be in the region of or close to the base element rotation axis or can have a radial distance therefrom, which is particularly relevant when the base element has a large diameter, e.g., 1 m or more.

[0048] The device according to the invention can be designed such that the means for applying the starting material and / or the means for smoothing, distributing and / or removing the starting material and / or the means for supplying gas and / or the means for aspirating gas or waste material are arranged or can be arranged for operation of the device in the base element internal space through which the base element rotation axis passes and which is at least partially surrounded by the base surface.

[0049] For example, energy application means or parts thereof can be used, for example the beam outlet of the energy beam application means may be located approximately in the center of the extent of the base surface in the axial direction parallel to the base element rotation axis, as well as other aforementioned means arranged inside the base element, however, it is also possible to arrange these means or energy application means or parts thereof at different positions in the axial extent.

[0050] The aforementioned means, including the energy application means or a part thereof, may also extend axially such that the base surface can be used, at least over substantially its entire axial extent, for example, for application of starting material and / or smoothing, distributing, removing starting material and / or supplying / suctioning gas.

[0051] The device according to the invention can be designed such that the means for applying the starting material and / or the means for smoothing, distributing and / or removing the starting material and / or the means for removing the starting material and / or the means for supplying gas and / or the means for aspirating gas or waste material are axially and / or radially shiftable. In this way the method for additive manufacturing can be influenced in various ways. In particular, it is possible to simultaneously solidify the starting material at at least one point on the base surface and to apply the starting material to at least one other point on the base surface. The axial shiftability can be so extensive that the beam outlet and / or further aforementioned means can also be led out of the base element.

[0052] The device according to the invention also comprises means for applying the starting material and / or means for smoothing, distributing and / or removing the starting material and / or means for supplying gas and / or means for aspirating gas or waste products, which are rotatably or pivotally mounted, in particular with an axis of rotation or pivot parallel to the axis of rotation of the base element.

[0053] The means for applying the starting material and / or the means for smoothing, distributing and / or removing the starting material and / or the means for supplying gas and / or the means for extracting gas or waste products can rotate or swing synchronously with the base element or move in a circular or helical path, for example along the treatment location on the part. However, said means are not used to rotate or swing or are used with an angular velocity different from that of the base element, so that instead of the application of the energy beam with the rotation of the base element, the energy beam impinges on the starting material only in the area intended for the completed layer of the part. In this case, a pulsed or discontinuous operation of the energy application means can be provided.

[0054] During the swinging movement or rotation of the means for applying the starting material, the starting material can be fed through a rotating passage, for example through at least one open axial end of the base element. However, it is also conceivable to place the stock of the required starting material or a part of it inside the base element. If necessary, it is also possible to interrupt production and replenish the stock.

[0055] The device according to the invention can be manufactured with a wide range of sizes of base element. An internal diameter of the base surface of 1 m or more or 2 m or more is conceivable, thus making it possible to arrange the necessary elements in the base element internal space, such as energy application means or means for applying starting material and / or means for smoothing, distributing and / or removing starting material and / or means for supplying gas and / or means for sucking gas or waste products, etc. However, depending on the desired shape, diameters significantly smaller than 1 m are also useful.

[0056] The means for applying the starting material and the means for smoothing, distributing and / or removing the starting material can be realized by a single device, for example an applicator for the starting material and a squeegee arranged thereon. The means for distributing the starting material can also be one that acts by a gas flow, in particular a nozzle, for example a slit nozzle. Alternatively or additionally, the gas flow can also be used for smoothing.

[0057] Furthermore, the special design of the device according to the invention makes it possible to vary the installation space of the base element or of the entire device in a simple manner in the axial direction, regardless of the diameter of the base element, i.e. by exchanging a base element as required or by using a base element whose axial extension can be changed, the available base surface can be enlarged or reduced in the axial direction.

[0058] Furthermore, the device according to the invention can also be designed such that, in a cross-sectional plane perpendicular to the base element rotation axis, the base surface concentrically surrounds the base element rotation axis at least on the main circumference. The base surface forms a body of revolution in so far as it concentrically and completely surrounds the base element rotation axis over all cross-sectional planes that intersect with the base surface. However, the base surface can also correspond to an incomplete body of revolution, which does not completely surround the base element rotation axis in the circumferential direction, but has at least one interruption in the circumferential direction. Thus, beams or materials can be introduced from the outside into the base element internal space or removed from the base element internal space, for example to remove excess starting material.

[0059] The device according to the invention can also be designed such that the base surface is cylindrical at least in a partial region extending in a direction parallel to the base element rotation axis and at least on the main circumference, for example the base element can be formed partially as a hollow cylinder.

[0060] The base surface may have, at both ends, as viewed in its axial extension, end walls extending, preferably perpendicularly, from the base surface in the direction of the axis of rotation of the base element, which hold the starting material within the base element at least during rotation of the base element, and at least one end wall may be movable or removable to facilitate emptying of the base element.

[0061] In principle, the base element can be open at one or both axial ends, to the extent that an energy beam or starting material or further elements can be fed from there, such as energy beam application means or parts thereof and / or means for applying starting material and / or means for smoothing, distributing and / or removing starting material and / or means for feeding gas and / or means for sucking gas or waste material. For this reason, both ends of the base element can be completely free of walls or supports. If necessary, the support and / or drive of the base element can be performed from the outside, for example by rollers.

[0062] Although the above description and the claims represent the method according to the invention and the device according to the invention as having one part, one base element, one base surface or one energy beam or other elements, each of which is designated singular, this is by way of example and not of limitation. The invention also includes variants having more than one of these elements, for example providing two or more base elements, each of which has at least one base surface, or two or more energy beams. It is also possible to implement multiple base surfaces, separated from one another, on the base element or on at least one base element. [Brief description of the drawings]

[0063] Preferred exemplary embodiments of the method according to the invention and the device according to the invention are explained below with reference to the figures. [Figure 1] FIG. 1 illustrates a first embodiment of a selective laser melting apparatus in axial cross section. [Diagram 2] FIG. 2 illustrates a side cross-sectional view of a second embodiment of a selective laser melting apparatus. [Diagram 3] FIG. 3 shows a third embodiment of a selective laser melting apparatus during the production of a rotationally symmetric part having an internal structure. [Figure 4] FIG. 4 illustrates a fourth embodiment of a selective laser melting apparatus with two laser optics for parallel processing. [Diagram 5] FIG. 5 illustrates a fifth embodiment of a selective laser melting apparatus. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0064] The drawings do not show a complete system for selective laser melting, but only the essential components of the invention, in particular the drive means for the laser radiation and the starting material, the control device and the supply device.

[0065] Figure 1 shows a schematic axial cross-section of a first design embodiment 1 of a system for selective laser melting, hereinafter referred to as the first LPBF system 1. The first LPBF system 1 has a base element 2, of which only the hollow cylindrical base surface 3 can be seen in the view of Figure 1.

[0066] The base element 2 is rotated by drive means, not shown here. The drive means can act on the base element 2, for example, by form-locking or force-locking. As starting material for additive production, powder 4 is illustrated here, which is applied to the base element 3 with a powder applicator 5. Due to the rotational movement in the direction indicated by the arrow around the base element rotation axis extending perpendicularly to the plane of the paper and the associated centrifugal acceleration, the powder 4 remains on the base surface 3. The powder application forms a powder bed 7. The powder applicator 5 can, for example, be moved in a circumferential direction relative to the base surface 3 only by the rotation of the base element 2 or additionally by further drive means, not shown here.

[0067] The squeegee 6 serves to distribute the powder 4 uniformly. An energy beam in the form of a laser beam 8 is irradiated onto the powder bed 7 via a laser optics 9. The laser beam 8 melts the powder in the powder bed 7 selectively in layers, whereby the lateral layer dimensions of the part to be produced are determined by the movement or motion of the laser beam 8 and the layer thickness is determined by the height of each new powder layer. When the melted layer cools, it hardens or solidifies, forming the first layer of the desired part 10, which is thus stacked one on top of the other. Correct focusing of the laser beam 8 onto the powder bed can be achieved by changing the laser optics 9 or by shifting the laser optics 9 relative to the base element rotation axis. The shifting of the laser optics 9 can be achieved, for example, via a first linear or straight axis 11.

[0068] It is also possible to move the laser optics 9 in another direction, for example on a second linear axis, not shown here, parallel to the base element rotation axis. Alternatively, the laser optics can extend over the entire axial length required for the production of the component or can act over a corresponding distance by a scanner device, not shown separately here, so that there is no need to shift the laser optics 9 parallel to the base element rotation axis.

[0069] The laser optics is mounted for rotation about an energy beam rotation axis parallel to the base element rotation axis, preferably coaxially, as will be explained in more detail in FIG. 5 by way of a further example of embodiment.

[0070] A protective gas or inert gas (Schutzgas) is released into the additive production area by a protective gas applicator 12 and collected by a gas collector 13. It can be seen that the application of the powder 4 and the production of the part 10 can take place simultaneously. Also, the gas flow emitted by the protective gas applicator 12 can assist or even cause the distribution and levelling of the powder 4 in the powder bed 7, so that the squeegee 6 can be omitted.

[0071] The protective gas applicator 12, the gas collector 13 and / or the powder applicator 5 can be radially and / or axially movable. The radial movability is useful for adapting to a growing part. The axial movability can accommodate an axially shifting processing area. The protective gas applicator 12, the gas collector 13 and / or the powder applicator 5 can also extend axially over the entire processing area.

[0072] The laser optics 9, the protective gas applicator 12, the gas collector 13 and / or the powder applicator 5 can rotate, swing or move on a circular or spiral path synchronously with the base element 2, i.e. with the same angular velocity, for example to follow the processing positions on the component 10. In this case, the laser optics 9 can be operated continuously. However, it is also possible, for example, to not rotate the laser optics 9 temporarily about its energy beam rotation axis or to rotate the laser optics 9 with an angular velocity different from the angular velocity of the base element, so that the laser irradiation is coordinated with the rotation of the base element 2, for example, such that the laser beam strikes only the area of ​​the layer of the component 10 to be finished on the powder bed 7. In this case, a pulsed or discontinuous operation of the laser is provided.

[0073] 2 shows a schematic cross-section of a second LPBF system 14 with a drum-shaped base element 16 having a hollow cylindrical base surface 15, here with a drive connection 17 for the engagement of a drive element, not shown, for the base element 16. In addition to a bottom piece 18 and a peripheral wall 19 for the base surface 15, the base element 16 can have a front end wall 20, in which an opening 21 is provided that allows access of a laser optics 22 with a feed 28 and an axial linear guide 23. On the outside of the base element 16, a radial linear guide 27 is provided for the laser optics 22. The radial linear guide 27 can alternatively also be arranged inside the base element 16. The linear guides 23, 27 are shown only symbolically and are combined in a manner not shown here with means for supporting and driving the rotation of the laser optics 22, also not shown.

[0074] Other elements such as a powder applicator or a protective gas applicator, which are not shown in FIG. 2 for clarity, can also be inserted via opening 21 and their spatial position can be changed, for example via a linear tube or via a rotational or swing axis.

[0075] The second LPBF system 14 shown is used, for example, to manufacture two parts 24, 25 which are closed in the circumferential direction of the base element 16 and each have an annular shape.

[0076] 3 shows a schematic cross-section of a base element 29 with a base surface 30 of the third LPBF system 26, whereby the base element 29 rotates in the direction of the arrow. A laser optics 31 is arranged in the base element 29, whereby an annular closed part 33 with a number of cavities 34 is produced by additive manufacturing from a powder bed 32, only one of which is referenced. Note that here the energy beam rotation axis of the laser optics 31 is not shown (see reference 46 in the fourth embodiment in FIG. 4).

[0077] FIG. 4 shows a schematic cross-section of a base element 35 having a base surface 36 of a fourth LPBF system 37, which rotates in the direction of the arrow around the rotation axis of the base element. A first laser optic 38 and a second laser optic 39 are arranged in the base element 35 and simultaneously apply a laser beam 41 to different points of a powder bed 40 to simultaneously form layers on two different parts 42 and 43. The first laser optic 38 and the second laser optic 39 can rotate around an energy beam rotation axis 46 that is coaxial with the base element rotation axis, and the angular velocities of the laser optics 38 and 39 can be temporarily the same or different therefrom to change the alignment of the laser beam 41 relative to the base element 35. When the base element 35 in its angular position is further rotated by an appropriate angle relative to the laser optics 38 and 39, the laser optics 38 and 39 can simultaneously provide two further parts 44 and 45, one layer each. Components which are further extended in the circumferential direction, in particular parts which are closed in the circumferential direction, can be treated simultaneously at different points using both laser optics 38 and 39. Although not shown here, the means for applying powder and / or the means for flowing protective gas can be provided in several ways, for example depending on the number of laser optics 38, 39.

[0078] FIG. 5 shows a fifth LPBF device 50 comprising a base element 51 with a base surface 52. The powder used as starting material for additive manufacturing is not shown. The base element 51 is driven by means not shown here to rotate with an angular velocity ω1, indicated by arrow 53. The drive can engage, for example, with the outer peripheral surface of the base element 51 by form-locking or force-locking. Inside the base element 51 a hollow shaft 55 is guided via a bearing 54. This bearing allows a rotational movement between the base element 51 and the hollow shaft 55 as well as an axial displacement, indicated by the double arrow. The hollow shaft 55 is driven by drive means not shown here to rotate with an angular velocity w2, indicated by arrow 56.

[0079] A laser beam 58 from a laser source (not shown) is coupled into the hollow shaft 55 via a rotary coupling 57. The rotary coupling makes it possible to operate the beam source (not shown) without a rotational movement. The rotary coupling 57 is preceded in the beam direction by an optical element 59, here represented simply by three optical lenses 60, which allows a controlled focusing of the laser beam 58.

[0080] The hollow shaft 55 has a mirror element 61 at its front end and is supported for a controllable scanning or swinging movement in the example shown. However, it can also be provided with a fixed mirror element, for example with a fixed angle of 90°, i.e. without a scanning device. By means of the mirror element, the focal point of the laser beam can thus be moved, for example parallel to the hollow shaft 55, i.e. axially, or also in other directions on the base surface 52 or on the powder surface, which are not shown here. This can be done in the case of a scanning or swinging device by correspondingly changing the inclination angle of the mirror element 61, or by axial displacement in the case of a mirror element with a fixed deflection angle. Instead of a mirror, it is of course also possible to use an optical deflection device, such as a prism. If the thickness of the powder layer changes, the focal position can be adjusted by the optical component 59.

[0081] The angular velocity ω256 of the hollow shaft 55 corresponds to the angular velocity with which the laser beam 58 rotates about the energy beam rotation axis, which here coincides with the central longitudinal axis of the hollow shaft 55. The angular velocity ω256 of the hollow shaft 55 can be made to coincide with the angular velocity ω153 of the base element 51, so that, neglecting the scanning motion controlled by the mirror 61, the energy beam 58 on one side and the base surface 52 on the other side or the surface of the powder layer, not shown here, do not exhibit any relative motion to each other at the impact point of the laser beam 58.

[0082] Advantageously, different angular velocities ω2 56 of the hollow shaft 55 and ω1 53 of the base element 51 are selected, which reduces the relative velocity between the incident laser beam 58 and the surface of the powder layer, ignoring a possible scanning movement of the laser beam 58. This relative velocity determines the speed of the process step and is, for example, at least 100 mm / s, typically 200 mm / s, up to 2 m / s or up to 5 m / s. The relative movement can be realised with ω2>ω1 or ω2<ω1.

[0083] The relative motion can also be achieved by the hollow shaft 55 and the base element 51 having opposite directions of rotation. The relative speed does not have to be constant during the manufacturing process but can also be varied. For example, different relative speeds can be provided at different axial positions. In additive manufacturing, the part is manufactured in successive layers one above the other. Different relative speeds can be provided for different layers of the part. Furthermore, positional variations in the intensity of the laser beam are possible for different axial positions and for different layers.

[0084] All of the presented exemplary embodiments can be modified in an appropriate manner with respect to the number of presented elements, such as laser optics, components, powder applicators, squeegees, protective gas applicators and / or gas collectors, etc. Instead of powders as starting materials for the illustrated exemplary embodiments, alternative materials are also conceivable, such as, for example, liquid, e.g. viscous starting materials. Furthermore, instead of a laser beam, alternative energy beams can also be used, such as, for example, an electron beam or an ultraviolet beam (UV radiation). [Explanation of symbols]

[0085] 1 1st LPBF device (Erste LPBF-Anlage) 2 Basiselement 3 Base surface 4 Pulver 5 Pulver Applikator 6 Squeegee (Rakel) 7 Powder bed (Pulverbet) 8 Laser Beam 9 Laser optics 10 Parts (Bauteil) 11 First Linear Axis 12 Protective gas applicator (Schutzgas-Applikator) 13 Gas recovery unit (Gassammler) 14 2nd LPBF device (Zweite LPBF-Anlage) 15 Base surface 16 Basiselement 17 Drive sockets 18 Bottom piece (Bodenstueck) 19 Perimeter Wall (Umfangswand) 20 Front end wall (Vordere Abschlusswand) 21 Oeffnung 22 Laser optics (Laseroptik) 23 Axial Linear Guide 24 Parts(Bauteil) 25 parts(Bauteil) 26 3rd LPBF device (Dritte LPBF-Anlage) 27 Radial Linear Guide 28 Supply Department (Zuleitung) 29 Basiselement 30 Base surface 31 Laser optics 32 Powder bed (Pulverbet) 33 Parts (Bauteil) 34 Cavity (Hohlraum) 35 Basiselement 36 Base surface 37 4th LPBF device (Vierte LPBF-Anlage) 38 Erste Laseroptik 39 Second Laser Optics (Zweite Laseroptik) 40 Powder Bed(Pulverbet) 41 Laser beam 42 Parts (Bauteil) 43 Parts (Bauteil) 44 Parts (Bauteil) 45 parts (Bauteil) 46 Energy beam rotation axis 50 5th LBPF device (Fuenfte LBPF-Anlage) 51 Basiselement 52 Base surface 53 Arrow (Pfeil) 54 Bearings (Lagerung) 55 Hollow shaft (Hohlwelle) 56 Arrow (Pfeil) 57 Rotary coupling (Drehkopplung) 58 Laser beam 59 Optical Block (Optischer Baustein) 60 Optical Lenses 61 Mirror element (Spiegelelement)

Claims

1. 1. A method for additive manufacturing comprising: a part is produced in layers by starting material being hardened by an energy beam irradiated by the energy beam irradiating means while said starting material is supported by a base surface arranged on the base element, the base element is moved with a rotational component having a base element axis of rotation while the energy beam impinges on the starting material; the starting material is held above the base surface by centrifugal acceleration generated via the rotational component; providing a rotational motion for at least a portion of the energy beam application means having an energy beam axis of rotation coaxial with the base element axis of rotation; The rotational movement of the base element and the rotational movement of the energy beam irradiation means are driven separately from each other; The energy beam application means is moved along a translation axis extending parallel to the base element rotation axis. method.

2. the relative velocity of the impact point of the energy beam on the base surface or on the surface of the starting material relative to the base surface or to the starting material is changed during the additive manufacturing; The method of claim 1.

3. the intensity of the energy beam is varied during the additive manufacturing; 3. The method according to claim 1 or 2.

4. The rotational movement of the energy beam irradiation means or at least a part of the energy beam irradiation means and the rotational movement of the base element are performed at different angular velocities.

4. The method according to claim 1 ,

5. The rotation direction of the rotational motion of the energy beam irradiation means or at least a part of the energy beam irradiation means and the rotation direction of the rotational motion of the base element are opposite to each other.

5. The method according to any one of claims 1 to 4.

6. the angular velocity of the rotational movement of the energy beam application means or at least a part of the energy beam application means is changed during additive manufacturing; 6. The method according to any one of claims 1 to 5.

7. The magnitude of the centrifugal acceleration acting on the starting material corresponds to at least the magnitude of the acceleration of gravity, corresponds to at least 1.5 times the magnitude of the acceleration of gravity, or corresponds to at least twice the magnitude of the acceleration of gravity; 7. The method according to any one of claims 1 to 6.

8. The magnitude of centrifugal acceleration changes during the manufacturing process.

8. The method according to any one of claims 1 to 7.

9. the part being constructed in layers; the local surface normal of the layer has at least one principal component that is parallel or non-parallel to the centrifugal acceleration; 9. The method according to any one of claims 1 to 8.

10. At least two parts are built on the same base element during the same manufacturing process; 10. The method of any one of claims 1 to 9.

11. On said base element at least one part is constructed which is closed in the circumferential direction of said base surface, 11. The method according to any one of claims 1 to 10.

12. The base element is at least partially hollow cylindrical, and a longitudinal central axis of the hollow cylindrical shape is used as a base element rotation axis for the rotational component.

12. The method of any one of claims 1 to 11.

13. The rotational component is combined with a further movement component for the movement of the base element.

13. The method of any one of claims 1 to 12.

14. The energy beam irradiation means is supported by an axial linear guide that is radially movable between the base element rotation axis and the base surface.

14. The method of any one of claims 1 to 13.

15. 1. An apparatus for additive manufacturing comprising: a base element having a base surface for receiving a starting material; an energy beam irradiation means provided for irradiating an energy beam in the direction of the base surface; a base element driving means for moving the base element with a rotational component having a base element rotation axis, the base surface extending along a direction parallel to the base element rotation axis; at least one energy beam rotation axis, coaxial with the base element rotation axis, for rotating at least a part of the energy beam application means; at least one axis of movement in addition to the energy beam rotation axis for moving at least a portion of the energy beam application means; Equipped with separate drives for the rotational movement of the base element and the rotational movement of the energy beam irradiation means; At least one of the additional axes of motion is a translation axis extending parallel to the base element axis of rotation. Device.

16. The magnitude of the centrifugal acceleration acting on the starting material corresponds to at least the magnitude of the acceleration of gravity, corresponds to at least 1.5 times the magnitude of the acceleration of gravity, or corresponds to at least twice the magnitude of the acceleration of gravity; 16. The apparatus of claim 15.

17. a focus adapting means for adapting the focus of the energy beam, 17. Apparatus according to claim 15 or 16.

18. Means for applying said starting material, and / or Means for smoothing, distributing and / or removing said starting material; and / or means for supplying gas, and / or a means for sucking gas or waste material, The base element rotation axis passes through and is arranged in a base element internal space that is at least partially surrounded by the base surface, or can be arranged for operation of the device; 18. Apparatus according to any one of claims 15 to 17.

19. means for applying said starting material, and / or means for smoothing, distributing and / or removing said starting material; and / or means for supplying gas, and / or The means for aspirating gas or waste material comprises: axially and / or radially shiftable; 20. The apparatus of claim 18.

20. Means for applying said starting material, and / or means for smoothing, distributing and / or removing said starting material; and / or means for supplying gas, and / or The means for aspirating gas or waste material comprises: Supported to be rotatable or swingable; 20. Apparatus according to claim 18 or 19.

21. In a cross section perpendicular to the base element rotation axis, the base surface concentrically surrounds the base element rotation axis at least along a major circumference.

21. Apparatus according to any one of claims 15 to 20.

22. the base surface is cylindrical at least in a partial region extending in a direction parallel to the base element rotation axis and at least along a major circumference, 22. The apparatus of claim 21.

23. the base element has at least one axial end a closing wall extending from the base surface in the direction of the base element rotation axis and being movable and / or removable; 23. Apparatus according to any one of claims 15 to 22.

24. The energy beam irradiation means is supported by an axial linear guide that is radially movable between the base element rotation axis and the base surface.

24. Apparatus according to any one of claims 15 to 23.

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