EP4171853A1

EP4171853A1 - Additive manufacturing method and device

Info

Publication number: EP4171853A1
Application number: EP21754910.4A
Authority: EP
Inventors: Henning Janssen; Florian Schmidt; Christian Brecher; Daniel Zontar
Original assignee: Fraunhofer Gesellschaft zur Forderung der Angewandten Forschung eV
Current assignee: Fraunhofer Gesellschaft zur Forderung der Angewandten Forschung eV
Priority date: 2020-06-26
Filing date: 2021-06-28
Publication date: 2023-05-03
Also published as: US20230211548A1; WO2021259428A1; DE102020116972A1; US11820047B2; JP2023532008A

Abstract

The invention relates to an additive manufacturing method in which a component (10, 42, 43, 44, 45) is produced in layers using an energy beam (8, 41, 58) which solidifies a starting material (4) and is irradiated by energy beam irradiating means (9, 22, 31, 38, 39, 55, 59, 61) while the starting material (4) is held by a base surface (3, 15, 30, 36, 52) arranged on a base element (2, 16, 29, 35, 51). While the starting material (4) is being irradiated with the energy beam (8, 41, 58), the base element (2, 16, 29, 35, 51) is moved by a rotational component which has a base element rotational axis, wherein the starting material (4) is held on the base surface (3, 15, 30, 36, 52) by a centrifugal acceleration generated by the rotational component. The invention is characterized in that a rotational movement is produced for at least some of the energy beam irradiating means (9, 22, 31, 38, 39, 55, 59, 61). Analogously, at least one energy beam rotational axis (46) is proposed for rotating at least some of the energy beam irradiating means (9, 22, 31, 38, 39, 55, 59, 61) in an additive manufacturing device in which the starting material (4) is held on a base surface (3, 15, 30, 36, 52) by a centrifugal acceleration.

Description

Process and device for additive manufacturing

The invention relates to a method for additive manufacturing according to the preamble of claim 1 and a device for additive manufacturing according to the preamble of claim 16.

Additive manufacturing in the sense of the invention concerned here means the layer-by-layer production of components from a starting material which, for. B. is in powder form, with irradiation of an energy beam such as a laser beam or an electron beam. From the prior art, for example, selective laser melting, also known as laser powder bed fusion (LPBF), selective laser sintering (e.g. SLS) or electron beam melting are known. Due to the layered structure, complex internal and external structures can be implemented in the three-dimensional components, such as cooling channels or support structures. Additive manufacturing offers, especially with the use of laser beams, a high potential for the implementation of digitally controlled process chains in the sense of Industry 4.0. This means that late customer interconnection points can be provided and standardized semi-finished products can be used. Areas of application are in particular the automotive sector, aerospace, medical technology as well as tool and mechanical engineering.

Since the development of the LPBF process in 1999, additive manufacturing has primarily established itself for the rapid production of prototypes and for small to medium-sized series of specific components. Since then, additive manufacturing has brought a paradigm shift in growing areas from largely subtractive process chains to generative processes. So far, however, additive manufacturing has been used relatively little in the production of high-volume components, since the established processes are usually even more economical there.

The low cost-effectiveness of additive manufacturing processes in many cases is due to the comparatively low construction rates and the associated high component costs. In addition, the additively manufactured surfaces often require post-processing. Other problems can arise from residual porosities in the component as well Loss of expensive, powdery base material can occur due to poor process efficiency.

So far, machine kinematics with a Cartesian coordinate system has prevailed for additive manufacturing, usually with a powder bed, which is lowered after completion of a layer of the component, and a 2-axis beam guidance for the energy beam.

In some process variants of additive manufacturing, a gas flow, in particular from a protective gas that prevents oxidation of the starting material, is used.

From EP 3357606 A1 a device for selective laser melting is known in which the laser beam with its processing path is guided over the powder bed in such a way that particles produced during processing are not blown onto the unprocessed powder bed by a gas stream directed at the component. In the illustrated embodiment, the direction of the gas flow is constant, while the direction of the processing path can be changed by a scanner unit of the laser device.

From DE 102018 109737 A1 a method and a device of the type mentioned are known in which a laser is used for the selective sintering of a powder material in a build-up chamber, the build-up chamber being annular and rotating relative to a powder storage system and the laser. The material is applied essentially with a direction of construction parallel to the axis of rotation of the base element. In this way, several components distributed in the ring can be manufactured additively, whereby the same laser scanner can successively sinter component layers on different components, while new powder can be applied or stripped for another component at the same time. This should enable a higher throughput.

A similar disclosure emerges from EP 2983896 B1, according to which a carrier for a The workpiece to be produced and a powder distributor for producing a powder bed are provided, the powder distributor and the support of the axis being rotatably arranged. A pot-shaped structure of the carrier is intended to cause the cylindrical wall to rotate together with the base when the carrier rotates, creating a relative movement between the wall of the process chamber in which the powder bed is produced and the rotating base of the process chamber, which is called The basis for the workpieces to be produced is avoided.

A 3D printing process is known from CN 206839165 U, with which cylinders or hollow cylinders with a larger diameter of e.g. more than 2 m can be produced. For this purpose, an overall cylindrical 3D printer is used, with the main construction direction being aligned parallel to the cylinder axis.

CN108015278 B discloses a 3D printer device in which the powder is distributed in a cylindrical powder distributor with a structure rotating about a z-axis on a floor perpendicular to the z-axis. The components to be printed are built up parallel to this z-axis.

DE 102010041 284 A1 discloses a method for selective laser sintering in which the powder is applied by means of a rotating powder distributor, the axis of rotation of which is aligned inside an annularly closed cross section of the component to be produced and perpendicular to the surface of the powder bed. The laser beam should be guided following the curved contour of the component, at least during a first linear energy input, in such a way that the contour is continuously reproduced by the sintered material.

From US 2020/0180224 A1 a method and a device for three-dimensional printing are known, the device having a frame rotating about an axis with a base surface on which three-dimensional objects are built up in a powder layer as starting material. The rotational movement of the frame causes a sufficient centrifugal force to act on the powder layer applied to the base surface, so that the powder layer is held continuously by the base surface and on this with an energy beam for 3D printing can be applied. The powder can be sprayed on by means of a pivotable arm which is mounted on the central rotating shaft for the frame, but does not rotate with it. At a radial distance from the rotating shaft of the frame, a beam source is fixed to a cardan ring in such a way that it can be pivoted in any direction.

Methods and devices for 3D printing with a rotating base surface and utilization of a centrifugal force acting on the powder are also known from DE 4308 189 C1 and DE 102018019 A1.

The invention is based on the technical problem of providing a method and a device for additive manufacturing which have kinematics that are alternative to the prior art and which offer improved options for influencing the starting material and the process control.

With regard to the method, the technical problem is solved with the characterizing features of claim 1. Advantageous embodiments emerge from the dependent method claims.

Thus, in a method for additive manufacturing, in which a component is manufactured in layers by means of an energy beam that solidifies a starting material and is radiated in by means of energy radiation radiation means, while the starting material is held by a base surface arranged on a base element, with the starting material being exposed to the energy beam the base element is moved with a rotational component having a base element rotational axis and the starting material is held on the base surface by means of a centrifugal acceleration generated by the rotational component, it is proposed that a rotational movement be provided for at least some of the energy beam irradiation means.

According to the method according to the invention, the starting material does not rest on the base surface due to the gravitational acceleration, but rather remains adhering to the base surface due to the centrifugal acceleration. The rotational component of the movement has a suitable angular velocity, that of sliding or falling of the starting material from the base surface, for example due to gravitational acceleration, is prevented. In this way, there is kinematics for the additive process that offers additional options for influencing the condition of the starting material or various parameters of the manufacturing process. For the first time it is proposed that a rotational movement be provided for at least some of the energy beam irradiation means. This means that not only the base element but also the energy beam can be rotated during the additive manufacturing process, which results in additional options for setting or changing the relative speed between the energy beam and the starting material to be processed. The rotational movement for at least some of the energy beam irradiation means has the consequence that the energy beam itself is guided in a rotating manner within the base element, so that the part of the energy beam running between the energy beam irradiation means and the starting material has an energy beam axis of rotation that is perpendicular to at least one component of the direction of propagation of the energy beam is aligned.

The energy beam irradiation means can have optical elements such as lenses, mirrors and / or light guides.

It can be particularly advantageous to carry out the method according to the invention in such a way that the rotational movement for the energy beam irradiation means or for at least some of the energy beam irradiation means is carried out with an energy beam rotation axis parallel to the base element rotation axis. In this way, the energy beam can be used without restriction in the complete angular range of 360 ° of a central angle of its rotation in the circumferential direction of the base element.

It is particularly advantageous if the axis of rotation of the base element and the axis of rotation of the energy beam are coaxial or can be aligned coaxially with one another. A coaxial alignment of the axes of rotation can mean, for example, that in every angular position of the rotating energy beam irradiation means or of the at least one rotating part of the energy beam irradiation means, the radial spacing of one The exit point for the energy beam to a base surface assumed to be cylindrical remains the same.

The method according to the invention can also be carried out in such a way that a relative speed of a point of impact of the energy beam on the base area or the surface of the starting material relative to the base area or relative to the starting material is varied during additive manufacturing. This results in additional parameters for the manufacturing process.

Furthermore, the method according to the invention can be carried out in such a way that the intensity of the energy beam is varied during additive manufacturing.

The variation of the relative speed as well as the intensity of the energy beam can take place in terms of time and / or location. Thus, different relative speeds and / or intensities can be provided for different coordinates in the axial direction, that is to say parallel to the axis of rotation of the base element, and / or for different layers when building components up in layers.

The method according to the invention can be carried out in such a way that the rotational movement of the energy beam irradiation means or of at least some of the energy beam irradiation means and the rotational movement of the base element are carried out at angular velocities that differ from one another. In this way, the relative speed of the energy beam to the starting material at the point of impact of the energy beam on the starting material can be influenced without having to change the rotational speed of the base element. This is advantageous because the base element, together with the starting material, has the significantly greater moment of inertia compared to the energy beam irradiation means.

Furthermore, the method according to the invention can be carried out in such a way that the direction of rotation of the rotational movement of the energy beam irradiation means or of at least some of the energy beam irradiation means and the direction of rotation of the rotational movement of the base element are opposite to one another. To this 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. It goes without saying that the direction of rotation of the rotational movement of the energy beam irradiation means or of at least some of the energy beam irradiation means and the direction of rotation of the rotational movement of the base element can be rectified. It is also possible to change the direction of rotation of the rotational movement of the energy beam irradiation means or of at least some of the energy beam irradiation means relative to the direction of rotation of the rotational movement of the base element, so that a larger range of relative speed between the energy beam and the starting material can be used.

The method according to the invention can also be carried out in such a way that the angular speed of the rotational movement of the energy beam irradiation means or of at least some of the energy beam irradiation means is changed during additive manufacturing. For example, this angular velocity could be adapted to a changing, for example increasing, layer thickness of the starting material. Thus, not only, as already mentioned, the relative speed between the point of impact of the energy beam and the starting material can be changed if necessary, but it can also be worked towards keeping the relative speed as constant as possible even with increasing layer thickness of the starting material, without doing this having to change the angular velocity of the base element.

The angular speed of the rotational movement of the base element can influence, for example, the formation of pores, the energy input or when a gas is used, e.g. B. a protective gas, can be taken on the gas flow. It is also possible to provide different orientations of the axis of rotation of the rotational component, for example parallel or perpendicular to the direction of gravitational acceleration, or any other desired orientation. The orientation of the axis of rotation can also be changed during the procedure. If the starting material is in powder form, for example, the powder dynamics can be influenced by varying the angular velocity. Increasing rotational speeds lead to higher contact pressure between the powder particles in a powder bed, which can reduce denudation, i.e. undesired removal of powder particles or entire layers due to gas flows or other influences, or spraying of powder particles (spatter ejection). In addition, the size and / or number of pores or gas inclusions in the component can be influenced via the centrifugal acceleration. It is also possible to influence the centrifugal acceleration with other forms of the starting material, for example with a viscous starting material.

The method according to the invention can be carried out in such a way that the amount of the centrifugal acceleration acting on the starting material corresponds at least to the amount of the gravitational acceleration. In this case it is also possible to operate the method according to the invention when the base element rotation axis of the rotation component is oriented perpendicular to the gravitational acceleration. The centrifugal acceleration can also be a multiple of the gravitational acceleration, e.g. the acceleration due to gravity, e.g. at least 1.5 times, more preferably at least twice the amount of the gravitational acceleration, in absolute numbers based on the acceleration due to gravity e.g. at least 15 m / s ² , at least 20 m / s ² or at least 50 m / s ² or at least 100 m / s ² . In particular, it can be advantageous to set the centrifugal acceleration in a targeted manner.

In addition, it can be advantageous to vary the centrifugal acceleration during a manufacturing process, for example also in the course of manufacturing the same module. This means that the process can be influenced in a completely new way during the process. For example, changing the centrifugal acceleration could influence the density of the starting material, which in turn can influence the structure of a component to be manufactured. It could e.g. B. can be achieved that gas inclusions migrate due to the higher pressure in the starting material in the direction of the axis of rotation and the number of pores in the component is reduced. Furthermore, the method according to the invention can be carried out in such a way that the component is built up with layers whose local surface normals have at least one main component parallel or antiparallel to the centrifugal acceleration. The starting material will usually assume an inner surface, the local surface normal of which is aligned antiparallel to the centrifugal acceleration. The component layers produced in the bed of the starting material by solidification, for example by welding, sintering or after melting, can also be aligned in a corresponding manner. The sequence of the built-up component layers thus generally extends radially in the direction of the axis of rotation of the base element.

The method according to the invention can also be carried out in such a way that at least two components are built up on the same base element in the same manufacturing method. These components can be spaced apart from one another in the circumferential direction and / or in the axial direction.

Furthermore, the method according to the invention can also be carried out in such a way that at least one component that is closed in the circumferential direction of the base surface is built up on the base element. Such a component can be, for example, ring-shaped, tubular or hollow-cylindrical. A plurality of components which are closed in the circumferential direction and which are spaced apart from one another in the axial direction can be manufactured simultaneously or one after the other. The component or at least one of the components can in particular be rotationally symmetrical.

Furthermore, the method according to the invention can be carried out in such a way that the base element is at least regionally shaped as a hollow cylinder and the longitudinal center axis of the hollow cylinder shape is used as the base element axis of rotation of the rotational component.

The base element can, however, also deviate from the hollow cylindrical shape or have structures, for example depressions, chambers or webs, in the base surface, which can help determine the shape of the component to be produced. The movement of the base element can also deviate from a pure rotation. For example, the rotation can be combined with further movement components, for example a pivoting movement about a pivoting axis perpendicular to the base element rotational axis of the rotational component or with translational movement (s), so that further possibilities of influencing the starting material to be solidified are given.

With regard to a device for additive manufacturing, comprising a base element with a base surface for receiving a starting material, energy beam irradiation means set up for irradiating an energy beam in the direction of the base area, and base element drive means for moving the base element with a rotational component having a base element rotation axis, the base area extending along a extends in the direction parallel to the base element rotation axis, the technical problem is solved by at least one energy beam rotation axis for the rotation of at least part of the energy beam irradiation means.

Advantageous further developments result from the dependent device claims.

An extension of the base surface along the direction parallel to the base element axis of rotation does not mean that the base surface must have a surface vector parallel to the base element axis of rotation, that is, runs parallel to the base element axis of rotation. Seen in the direction of the base element axis of rotation, the base surface can therefore also run inclined at least in some sections. As will be explained further below, the base surface can therefore in particular deviate from a hollow cylindrical shape.

The energy beam irradiation means can, for example, means for beam shaping or means for beam guidance, e.g. B. have one or more radiation guide fibers, mirrors or other optical elements, or a scanner device. The energy beam can be a laser beam or another one to solidify the starting material be a suitable energy beam, for example an electron beam or, especially in the case of liquids as the starting material, a beam formed with UV radiation.

The base element drive means are designed to rotate the base element at a sufficiently high angular velocity to hold the starting material on the base surface due to the centrifugal acceleration acting on it. The amount of the centrifugal acceleration acting on the starting material preferably corresponds to at least the amount of the gravitational acceleration.

The device according to the invention can also have at least one additional axis of movement to the axis of rotation of the energy beam for the movement of at least part of the energy beam irradiation means. In the case of the part of the energy beam radiation means which is movable for the rotation or for the additional axis of movement, it can be, for. B. be a beam output to which the energy beam is supplied via suitable means, z. B. mirrors, beam guiding fibers and / or other optical elements.

At least one of the additional axes of movement can be a pivot axis. It is thus possible for the energy beam irradiation means or their movable part to rotate or pivot with the base element in the same orientation and angular speed. For the layer structure, the energy beam can be guided over the starting material by suitable means, for example with a scanner device or with other beam deflection means which are part of the energy beam irradiation means or are provided separately. The rotation or the pivoting movement of the energy beam irradiation means or of the movable part thereof does not necessarily have to match the rotation of the base element in terms of angular velocity. It is also conceivable to temporarily suspend the rotation or the pivoting of the energy beam irradiation means or of the movable part thereof or to use an angular velocity which deviates from the angular velocity of the base element. If the energy beam irradiation means or the movable part thereof are not rotating or pivoting or deviate in their angular velocity from that of the base element, the irradiation can be coordinated with the rotation of the base element, for example by activating the energy beam always then or for irradiating the starting material or the Component is released when the area of the starting material to be processed or the component that has already been partially manufactured has reached a suitable position. In this case, there is pulsed irradiation, that is to say irradiation which is interrupted once or several times during one revolution of the base element relative to the energy irradiation means. The irradiation time can be calculated, for example, from the rotational speed of the base element and the current inside diameter of the starting material, for example the powder bed, and the diameter of the incident energy beam. Furthermore, the times at which the irradiation on the starting material or the component begins and / or ends can be synchronized with the angular position of the base element. In the case of components that are closed in the circumferential direction of the rotational movement of the base surface, the effect of the jet can also take place continuously in the course of at least one rotation of the base element.

The device according to the invention can also be designed in such a way that at least one of the additional movement axes is a translation axis, in particular a linear axis. Such a translation axis can also be provided in addition to the at least one rotation axis for the energy beam radiation means or for the movable part thereof. The at least one translation axis can in particular be provided for a movement parallel and / or perpendicular to the base element rotation axis. The translation axis, which has at least one component parallel to the base element rotation axis, can be designed in such a way that it enables at least part of the energy irradiation means or the movable part thereof to be moved into or out of a base element interior.

Rotation axes, pivot axes and translation axes can be located in the area or in the vicinity of the base element rotation axis or have a radial distance from it. Such a distance can be particularly useful when when the base element has a large diameter of, for example, more than 1 m.

The device according to the invention can also be designed so that means for applying the starting material and / or means for smoothing, distributing and / or removing the starting material and / or means for supplying a gas and / or means for sucking off a gas or waste products, within a base element inner space traversed by the base element rotation axis and at least partially surrounded by the base surface are arranged or can be arranged therein for the operation of the device.

For example, the energy beam radiation means or a part thereof, e.g. B. the beam output of the energy beam irradiation means, be arranged approximately centrally in the axial extension of the base surface given parallel to the base element rotation axis. The same applies to the other aforementioned means arranged in the interior of the base element. These means or the energy beam irradiation means or part thereof can, however, also be arranged at different positions along the axial extent.

The aforementioned means, including the energy beam radiation means or part thereof, can also extend in the axial direction in such a way that the base surface can be operated over at least almost its entire axial extent, e.g. with the application of raw material and / or smoothing, distribution or removal of raw material and / or supply / suction of a gas.

The device according to the invention can also be designed so 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 a gas and / or the means for sucking off a gas or of waste products are axially and / or radially displaceable. This means that the additive manufacturing process can be influenced in a variety of ways. In particular, it is possible to simultaneously solidify the starting material at at least one point on the base surface and to apply starting material to at least one other point on the base surface. The axial The displaceability can be so extensive that the beam outlet and / or the further aforementioned means can also be guided out of the base element.

The device according to the invention can also be designed so 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 a gas and / or the means for sucking off a gas or of waste products are rotatably or pivotably mounted, in particular with a rotation or pivot axis parallel to the base element rotation axis.

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 a gas and / or the means for sucking off a gas or waste products can rotate or pivot synchronously with the base element move on a circle or spiral path in order to follow the processing location, for example on the component. It is also conceivable, however, not to use the aforementioned means or to rotate or pivot them at an angular speed that deviates from the angular speed of the base element and instead to coordinate the radiation of the energy radiation with the rotation of the base element in such a way that the energy radiation is only in the area to be manufactured Layers of the component strikes the base material. In this case, there can be a pulsed or discontinuous operation of the energy beam radiation means.

In the event of a pivoting movement or a rotation of the means for applying the starting material, the starting material can be supplied, for example, via a rotary feedthrough, for example via at least one open axial end of the base element. However, it is also conceivable to arrange the necessary supply of the starting material or a part thereof in the interior of the base element. If necessary, production can be interrupted to refill the supply.

The device according to the invention can be manufactured with the most varied of sizes of the base element. Inner diameter for the base area in the range of 1 m or 2 m or more are conceivable and thus enable the arrangement of the required elements, such as. B. Energy radiation means or 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 a gas and / or the means for sucking off a gas or waste products, in the base element Inner space. However, diameters of significantly less than 1 m can of course also be useful, depending on the desired geometry.

The means for applying the starting material and the means for smoothing, distributing and / or removing the starting material can be implemented by a unitary device, for example by an applicator for the starting material and a doctor blade arranged thereon. The means for distributing the starting material can also be those which act by means of a gas stream, in particular means which have a nozzle, e.g. B. have a slot nozzle. The gas flow can alternatively or additionally also be used for smoothing.

The special design of the device according to the invention also allows the installation space for the base element or the entire device to be changed in the axial direction in a simple manner, regardless of the diameter of the base element. The usable base area can thus be expanded or shortened in the axial direction if necessary, for example by replacing the base element or using a base element whose axial extent can be changed.

Furthermore, the device according to the invention can also be designed in such a way that, in a sectional plane perpendicular to the base element rotation axis, the base surface concentrically encloses the base element rotation axis at least over the predominant circumference. Insofar as the base surface concentrically and completely surrounds the base element axis of rotation over all cutting planes intersecting the base surface, the base surface forms a body of revolution. However, the base surface can also correspond to an incomplete body of revolution which does not completely surround the base element axis of rotation in the circumferential direction, but rather has at least one interruption in the circumferential direction, so that radiation or matter from the outside in the base element interior can be introduced or can leave the base element interior, for example to remove excess starting material.

The device according to the invention can also be designed in such a way that the base surface is cylindrical in shape at least in a partial area extending in a direction parallel to the base element rotation axis and at least over the predominant circumference. So the base element z. B. be shaped in places as a hollow cylinder.

The base surface, viewed in the direction of its axial extent, can have end walls at its ends which extend from the base surface, preferably perpendicularly, in the direction of the base element rotation axis and which hold the starting material in the base element at least during the rotation of the base element. At least one end wall can also be movable or removable in order to facilitate emptying of the base element.

In principle, the base element can be opened so wide at one or both axial ends that the energy beam or starting material or other elements, e.g. B. the energy beam irradiation means or a part thereof and / or 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 a gas and / or the means for sucking off a gas or from waste products. For this purpose, the base element can be completely free of walls or brackets at both ends. If necessary, the base element can be supported and / or driven from the outside, for example by means of rollers.

Insofar as the previous description and claims represent the method according to the invention and the device according to the invention with a component, a base element, a base surface or an energy beam, or other elements in each case in the singular, this is exemplary and not a restriction. The invention thus also includes variants with more than one of these elements, for example two or more base elements each having at least one base area or two or more energy beams can be provided. There can also be several mutually delimited base surfaces can be realized in the base element or in at least one of the base elements.

In the following, preferred exemplary embodiments of the method according to the invention and the device according to the invention are described with reference to figures.

It shows schematically and in partial representation

1: a first embodiment of a system for selective laser melting in axial cross section,

2: a second embodiment of a system for selective laser melting in a lateral cross-section,

3: a third embodiment of a system for selective laser melting with production of a rotationally symmetrical component with internal structures,

4: a fourth embodiment of a system for selective laser melting with two laser optics for parallel processing, and

5: a fifth embodiment of a system for selective laser melting.

The figures do not show the respective system for selective laser melting in their completeness, but rather limited in each case to the components essential for the invention. In particular, the systems still have drive means, control units and feed devices for laser radiation and raw material.

1 shows schematically in an axial cross section a first embodiment 1 of a system for selective laser melting (hereinafter referred to as the first LPBF system 1 for short). The first LPBF system 1 has a base element 2, of which only a hollow cylindrical base surface 3 can be seen in the illustration in FIG. 1. The base element 2 is rotated by drive means not shown here. The drive means can, for example, act on the base element 2 from the outside in a form-fitting or force-fitting manner. A powder 4, which is applied to the base surface 3 with a powder applicator 5, is used here as an example of the starting material for additive manufacturing. Due to the direction of rotation around a base element rotation axis, which runs perpendicular to the plane of the drawing, and the associated centrifugal acceleration, the powder 4 remains on the base surface 3. With the powder application, a powder bed 7 is created. The powder applicator 5 can be moved in the circumferential direction relative to the base surface 3, for example solely by rotating the base element 2 or additionally by separate drive means (not shown here).

A doctor blade 6 ensures uniform distribution of the powder 4. An energy beam in the form of a laser beam 8 is radiated onto the powder bed 7 via laser optics 9. With the laser beam 8, the powder is selectively melted in a layer in the powder bed 7, the lateral layer dimensions of the component to be created being determined by a movement of the laser beam 8 and the layer thicknesses being determined by the height of the new powder layer. As the melted layer cools, the material solidifies to form a first layer of a desired component 10, which is built up successively in this way. The correct focusing of the laser beam 8 on the powder bed can be achieved by changing the laser optics 9 or by shifting the laser optics 9 relative to the axis of rotation of the base element. The displacement of the laser optics 9 can take place, for example, via a first linear axis 11.

The laser optics 9 can also be moved in further directions, for example via 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 act on a corresponding distance by means of a scanner unit not shown separately here, so that a displacement of the laser optics 9 parallel to the base element rotation axis is not necessary. The laser optics are mounted in such a way that they can be rotated about a preferably coaxial, energy beam rotation axis parallel to the base element rotation axis, as is explained in more detail in FIG. 5 on the basis of a further exemplary embodiment.

A protective gas is emitted in the area of additive manufacturing by means of a protective gas applicator 12, which is collected by means of a gas collector 13. It can be seen that the application of the powder 4 and the production of the component 10 can take place simultaneously.

The gas flow emitted by the protective gas applicator 12 can also support or even effect the distribution and smoothing of the powder 4 in the powder bed 7, so that the doctor blade 6 can be dispensed with.

The protective gas applicator 12, the gas collector 13 and / or the powder applicator 5 can be moved radially and / or axially. The radial movability is helpful for adapting to the growing component. The axial displaceability can serve to adapt to a machining area that is shifting in the axial direction. The protective gas applicator 12, the gas collector 13, and / or the powder applicator 5 can, however, also extend in the axial direction over the entire processing area.

The laser optics 9, the protective gas applicator 12, the gas collector 13 and / or the powder applicator 5 can rotate synchronously, ie with the same angular speed as the base element 2, pivot or move on a circular or spiral path around the processing location, for example on the component 10, to follow. The laser optics 9 can be operated continuously in this case. However, it is also conceivable, for example, not to rotate the laser optics 9 about its energy beam rotation axis at times or to rotate at an angular speed that deviates from the angular speed of the base element and to coordinate the laser radiation with the rotation of the base element 2 in such a way that the laser radiation is only in the area of the Layers of the component 10 to be manufactured impinges on the powder bed 7. In this case, pulsed or discontinuous operation of the laser is given. 2 shows schematically in cross section a second LPBF system 14 with a base element 16 having a hollow cylindrical base surface 15, which is drum-shaped and has a drive connector 17 for the engagement of a drive element (not shown here) for the base element 16. In addition to a bottom piece 18 and the peripheral wall 19 for the base surface 15, the base element 16 comprises a front end wall 20 with an opening 21 which allows access for laser optics 22 with a feed line 28 and an axial linear guide 23. A radial linear guide 27 for the laser optics 22 is provided outside the base element 16. The radial linear guide 27 can alternatively also be arranged within the base element 16. The linear guides 23 and 27 are shown only symbolically and are combined in a manner not shown here with the means for mounting and driving a rotation of the laser optics 22, also not shown.

Other elements, such as B. a powder applicator or a protective gas applicator, are not shown in Fig. 2 for the sake of clarity, but can also be introduced via the opening 21 and their spatial position can be changed, for example via linear guides or via rotary or pivot axes.

With the illustrated second LPBF system 14, two components 24 and 25 are produced, for example, which can be closed in the circumferential direction of the base element 16 and, for example, each have a ring shape.

3 shows schematically a base element 29 with a base surface 30 of a third LPBF system 26 in cross section, the base element 29 rotating in the direction of the arrow. Arranged in the base element 29 are laser optics 31, by means of which, by additive manufacturing, an annularly closed component 33 with cavities 34 is produced from a powder bed 32, only one of which is provided with a reference number. The axis of rotation of the energy beam (see 46 for the fourth exemplary embodiment in FIG. 4) for the laser optics 31 is not shown here.

Fig. 4 shows schematically a base element 35 with a base surface 36 of a fourth LPBF system 37 in cross section, the base element 35 in the direction of the arrow around the Base element rotation axis rotates. In the base element 35, a first laser optics 38 and a second laser optics 39 are arranged, which simultaneously apply laser radiation 41 to different locations of a powder bed 40 for the simultaneous formation of layers on two different components 42 and 43. The first laser optics 38 and the second laser optics 39 can be rotated around the energy beam rotation axis 46 which is coaxial to the base element rotation axis, wherein the angular speed of the laser optics 38 and 39 can be temporarily identical to that of the base element 35 or different therefrom, around the alignment of the laser beams 41 to change relative to the base element 35. When the base element 35 is further rotated in its angular position relative to the laser optics 38 and 39 by a suitable angle, the laser optics 38 and 39 can provide two further components 44 and 45 each with a layer at the same time. By means of the two laser optics 38 and 39, a component that expands further in the circumferential direction, in particular one that is closed in the circumferential direction, can be processed simultaneously at different points. Means, not shown here, for applying the powder and / or for flowing a protective gas through it can also be provided multiple times, for example corresponding to the number of laser optics 38, 39.

5 shows a fifth LPBF system 50 with a base element 51 having a base area 52. A powder to be used as a starting material for additive manufacturing is not shown. The base element 51 is driven by means of means, not shown here, for rotation at an angular velocity wi, symbolized by the arrow 53. The drive can act on the outside of the base element 51 in a form-fitting or force-fitting manner, for example. A hollow shaft 55 is guided into the interior of the base element 51 via a bearing 54. The mounting allows both a rotational movement and an axial displacement indicated by the double arrow between the base element 51 and the hollow shaft 55. The hollow shaft 55 is driven to rotate at the angular speed 002, symbolized by the arrow 56, via drive means (not shown here).

Laser radiation 58 from a laser source, not shown here, is coupled into the hollow shaft 55 via a rotary coupling 57. The rotary coupling makes it possible to operate the radiation source (not shown) without a rotary movement. The rotary coupling 57 an optical module 59, here merely symbolized by three optical lenses 60, is connected upstream in the beam direction, with which a controlled focus adjustment for the laser beam 58 is possible.

At its front end, the hollow shaft 55 has a mirror element 61 which, in the example shown, is mounted for a controllable scanning or pivoting movement. However, a fixed mirror element with a fixed angle of e.g. 90 ° can also be provided, i.e. without a scanning device. By means of the mirror element, the focus of the laser radiation can thus be moved in a controlled manner, e.g. parallel to the hollow shaft 55, i.e. in the axial direction, or in other directions on the base surface 52 or a powder surface (not shown here). In the case of the scanning or pivoting device, this can be done by correspondingly changing the angle of inclination of the mirror element 61 or, in the case of a mirror element with a fixed deflection angle, by axial displacement. Instead of a mirror, alternative optical deflection devices, such as a prism, can of course also be used. As the thickness of the powder layer changes, the focus position can be adjusted by means of the optical module 59.

The angular speed 00256 of the hollow shaft 55 corresponds to the angular speed with which the laser beam 58 rotates about its energy beam axis of rotation, here coinciding with the central longitudinal axis of the hollow shaft 55. The angular speed 00256 of the hollow shaft 55 can match the angular speed wi 53 of the base element 51, so that the energy beam 58 on the one hand and the base surface 52 or the surface of a powder layer (not shown here) on the other side at the point of impact of the laser beam 58 does not have any relative movement have to each other, if one disregards a scanning movement controlled by the mirror 61.

It is advantageous to choose different angular velocities 00256 of the hollow shaft 55 and wi 53 of the base element 51 so that, neglecting a possible scanning movement of the laser beam 58, there is a relative velocity between the incident laser beam 58 and the surface of the powder layer. This Relative speed determines the speed of the process progress and is, for example, at least 100 mm / s, typically 200 mm / s and up to 2 m / s or up to a maximum of 5 m / s. The relative movement can be achieved with 002> wi or with 002 <wi. The relative movement can also be achieved in that the hollow shaft 55 and base element 51 have opposite directions of rotation.

The relative speed does not have to be constant during the manufacturing process, but can also be changed. For example, different relative speeds can be provided at different axial positions. With additive manufacturing, components are manufactured in successive layers. Different relative speeds can be provided for different layers of the component. In addition, a local variation of the intensity of the laser beam for different axial positions and different layers is possible.

All of the exemplary embodiments presented can be varied in a suitable manner with regard to the number of elements presented, such as laser optics, components, powder applicators, squeegees, inert gas applicators and / or gas collectors. Instead of powder, an alternative material, such as a viscous starting material, for example a liquid, is also conceivable as the starting material in the exemplary embodiments shown. In addition, an alternative energy radiation, for example electron radiation or ultraviolet radiation (UV radiation), can also be used instead of laser radiation.

List of reference symbols

1 First LPBF system 30 base area

2 base element 31 laser optics

3 base area 32 powder bed

4 powder 33 component

5 powder applicator 34 cavity

6 squeegee 35 base element

7 powder bed 36 base area

8 Laser beam 37 Fourth LPBF system

9 Laser optics 38 First laser optics

10 Component 39 Second laser optics

11 First linear axis 40 powder bed

12 Inert gas applicator 41 Laser radiation

13 Gas collector 42 component

14 Second LPBF system 43 component

15 base surface 44 component

16 base element 45 component

17 Drive connection 46 Energy beam rotation axis

18 Floor piece 50 Fifth LBPF system

19 Perimeter wall 51 base element

20 Front end wall 52 Base area

21 opening 53 arrow

22 Laser optics 54 Storage

23 Axial linear guide 55 Hollow shaft

24 component 56 arrow

25 Component 57 Rotary coupling

26 Third LPBF system 58 Laser radiation

27 Radial linear guide 59 Optical module

28 Supply line 60 optical lens

29 base element 61 mirror element

Claims

1. A method for additive manufacturing, in which a component (10, 42, 43, 44, 45) by means of a starting material (4) solidifying, by means of energy radiation radiation means (9, 22, 31, 38, 39, 55, 59, 61) irradiated energy beam (8, 41, 58) is produced in layers, while the starting material (4) is supported by a base surface (3,

15, 30, 36, 52), with the base element (2, 16, 29, 35, 51) having a base element axis of rotation during the application of the energy beam (8, 41, 58) to the starting material (4) Rotary component is moved, the starting material (4) being held on the base surface (3, 15, 30, 36, 52) by means of a centrifugal acceleration generated by the rotational component, characterized in that for at least some of the energy beam irradiation means (9, 22, 31 , 38, 39, 55, 59, 61) a rotational movement is provided.

2. The method according to claim 1, characterized in that the rotational movement for the energy beam radiation means (9, 22, 31, 38, 39, 55, 59, 61) or for at least some of the energy beam radiation means (9, 22, 31, 38, 39 , 55, 59, 61) is carried out with an energy beam rotation axis (46) parallel to the base element rotation axis.

3. The method according to claim 2, characterized in that the base element rotation axis and the energy beam rotation axis (46) are coaxial or can be aligned coaxially with one another.

4. The method according to any one of the preceding claims, characterized in that a relative speed of a point of impact of the energy beam (8, 41, 58) on the base surface (3, 15, 30, 36, 52) or the surface of the starting material (4) is varied relative to the base surface (3, 15, 30, 36, 52) or relative to the starting material (4) during additive manufacturing.

5. The method according to any one of the preceding claims, characterized in that the intensity of the energy beam (8, 41, 58) is varied during additive manufacturing.

6. The method according to any one of the preceding claims, characterized in that the rotational movement of the energy beam irradiation means (9, 22, 31, 38, 39, 55, 59, 61) or of at least some of the energy beam irradiation means (9, 22, 31, 38, 39, 55, 59, 61) and the rotational movement of the base element (2, 16, 29, 35, 51) can be carried out at angular velocities that differ from one another.

7. The method according to any one of the preceding claims, characterized in that the direction of rotation of the rotational movement of the energy beam radiation means (9, 22, 31, 38, 39, 55, 59, 61) or of at least part of the energy beam radiation means (9, 22, 31, 38, 39, 55, 59, 61) and the direction of rotation of the rotational movement of the base element (2, 16, 29, 35, 51) are opposite to one another.

8. The method according to any one of the preceding claims, characterized in that the angular speed of the rotational movement of the energy beam irradiation means (9, 22, 31, 38, 39, 55, 59, 61) or of at least part of the energy beam irradiation means (9, 22, 31, 38, 39, 55, 59, 61) is changed during additive manufacturing.

9. The method according to any one of the preceding claims, characterized in that the amount of the centrifugal acceleration acting on the starting material (4) corresponds to at least the amount of the gravitational acceleration, preferably at least 1.5 times, more preferably at least twice the amount of the gravitational acceleration.

10. The method according to any one of the preceding claims, characterized in that the amount of centrifugal acceleration is changed in the course of the manufacturing process.

11. The method according to any one of the preceding claims, characterized in that the component (10, 42, 43, 44, 45) is built up in layers, the local surface normals of the layers having at least one main component parallel or antiparallel to the centrifugal acceleration.

12. The method according to any one of the preceding claims, characterized in that at least two components (10, 42, 43, 44, 45) are built on the same base element (2, 16, 29, 35, 51) in the same manufacturing process.

13. The method according to any one of the preceding claims, characterized in that at least one component (10, 42, 43, 44, 45) closed in the circumferential direction of the base surface is built up on the base element (2, 16, 29, 35, 51).

14. The method according to any one of the preceding claims, characterized in that the base element (2, 16, 29, 35, 51) is at least partially hollow cylindrical and the longitudinal center axis of the hollow cylindrical shape is used as the base element axis of rotation of the rotational component.

15. The method according to any one of the preceding claims, characterized in that the rotation component is combined with further movement components for the movement of the base element (2, 16, 29, 35, 51).

16. Device for additive manufacturing, comprising a base element (2, 16, 29, 35, 51) with a base surface (3, 15, 30, 36, 52) for receiving a starting material (4) for irradiating an energy beam (8, 41, 58) in the direction of the base surface (3, 15, 30, 36, 52) arranged energy beam radiation means (9, 22, 31, 38, 39, 55, 59, 61), and Base element drive means for moving the base element (2, 16, 29, 35, 51) with a rotational component having a base element axis of rotation, the base surface (3, 15, 30, 36, 52) extending along a direction parallel to the base element axis of rotation, characterized by at least one energy beam rotation axis (46) for rotating at least part of the energy beam irradiation means (9, 22, 31, 38, 39, 55, 59, 61).

17. The device according to claim 16, characterized in that the amount of the centrifugal acceleration acting on the starting material (4) corresponds to at least the amount of the gravitational acceleration, preferably at least 1.5 times, more preferably at least twice the amount of the gravitational acceleration.

18. The device according to claim 16 or 17, characterized by at least one axis of movement additional to the axis of rotation of the energy beam (46) for the movement of at least part of the energy beam irradiation means (9, 22, 31, 38, 39, 55, 59, 61).

19. The device according to claim 18, characterized in that at least one of the additional axes of movement is a pivot axis.

20. The device according to claim 18 or 19, characterized in that at least one of the additional movement axes is a translation axis, in particular a linear axis.

21. Device according to one of claims 16 to 20, characterized by focus adjustment means (59) for adjusting a focus of the energy beam (8, 41, 58).

22. Device according to one of claims 16 to 21, characterized in that means for applying (5) the starting material (4) and / or means for smoothing, distributing and / or removing the starting material (4) and / or Means for supplying a gas (12) and / or means for sucking off a gas or waste products (13) within a base element traversed by the axis of rotation of the base element and at least partially surrounded by the base surface (3, 15, 30, 36, 52) - Are arranged inside or can be arranged therein for the operation of the device.

23. The device according to claim 22, characterized in that the means for applying (5) the starting material (4) and / or the means for smoothing, distributing and / or removing (6) the starting material (4) and / or the means for Supply of a gas (12) and / or the means for sucking off a gas or waste products (13) are axially and / or radially displaceable.

24. The device according to claim 22 or 23, characterized in that the means for applying (5) the starting material (4) and / or the means for smoothing, distributing and / or removing (6) the starting material (4) and / or the Means for supplying a gas (12) and / or the means for sucking off a gas or waste products (13) are rotatably or pivotably mounted.

25. Device according to one of claims 16 to 24, characterized in that in a section plane perpendicular to the base element rotation axis the base surface (3, 15, 30, 36, 52) concentrically encloses the base element rotation axis at least over the predominant circumference.

26. The device according to claim 25, characterized in that the base surface (3, 15, 30, 36, 52) is cylindrical in shape at least in a partial area extending in a direction parallel to the base element rotation axis and at least over the predominant circumference.

27. Device according to one of claims 16 to 26, characterized in that the base element (2, 16, 29, 35, 51) at at least one axial end extends from the base surface (3, 15, 30, 36, 52) in Has direction to the base element rotation axis extending and movable and / or removable end wall (20).