ADDITIVE MANUFACTURING METHOD AND DEVICE

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.

Claims

1-27. (canceled)

28. An additive manufacturing method in which a component is manufactured in layers by means of an energy beam, which solidifies a starting material and is irradiated by energy beam irradiation means while the starting material is held by a base surface arranged on a base element, wherein, while the starting material is being irradiated with the energy beam, the base element is moved by a rotational component which has a base element rotational axis, wherein the starting material is held on the base surface by a centrifugal acceleration generated by the rotational component, wherein for at least one part of the energy beam irradiation means a rotational movement with an energy beam rotational axis coaxial to the base element rotational axis is provided, wherein the base element rotational movement and the energy beam irradiation means rotational movement are each driven separately and the energy beam irradiation means are moved along a translational axis parallel to the base element rotational axis.

29. The method according to claim 28, characterized in that, during additive manufacturing, a relative velocity of an impact point of the energy beam on the base surface or the surface of the starting material is varied relative to the base surface or relative to the starting material.

30. The method according to claim 28, characterized in that the intensity of the energy beam is varied during additive manufacturing.

31. The method according to claim 28, characterized in that the rotational movement of the energy beam irradiation means or of the at least one part of the energy beam irradiation means and the rotational movement of the base element are carried out at angular velocities deviating from one another.

32. The method according to claim 28, characterized in that the rotational direction of the rotational movement of the energy beam irradiation means or of the at least one part of the energy beam irradiation means and the rotational direction of the rotational movement of the base element are opposite to one another.

33. The method according to claim 28, characterized in that the angular velocity of the rotational movement of the energy beam irradiation means or of the at least one part of the energy beam irradiation means is changed during additive manufacturing.

34. The method according to claim 28, characterized in that the amount of centrifugal acceleration acting on the starting material is at least equal to the amount of gravitational acceleration, preferably at least 1.5 times, further preferably at least twice the amount of gravitational acceleration.

35. The method according to claim 28, characterized in that the amount of centrifugal acceleration is changed in the course of the manufacturing method.

36. The method according to claim 28, characterized in that the component is built in layers, wherein the local surface normals of the layers have at least one principal component parallel or antiparallel to the centrifugal acceleration.

37. The method according to claim 28, characterized in that at least two components are built on the same base element in the same manufacturing method.

38. The method according to claim 28, characterized in that at least one component closed in the circumferential direction of the base surface is built on the base element.

39. The method according to claim 28, characterized in that the base element is in the shape of a hollow cylinder, at least in some areas, and the longitudinal center axis of the hollow cylinder shape is used as the base element rotational axis of the rotational component.

40. The method according to claim 28, characterized in that for the movement of the base element the rotational component is combined with further movement components.

41. An additive manufacturing device, comprising a base surface for receiving a starting material, energy beam irradiation means configured to irradiate an energy beam in the direction of the base surface, base element drive means for moving the base element with a rotational component having a base element rotational axis, wherein the base surface extends along a direction parallel to the base element rotational axis, and at least one energy beam rotational axis coaxial to the base element rotational axis for the rotation of at least one part of the energy beam irradiation means, and at least one axis of movement additional to the energy beam rotational axis for moving at least one part of the energy beam irradiation means, wherein separate drives for the rotational movement of the base element and the rotational movement of the energy beam irradiation means, wherein at least one of the additional axes of movement is a translational axis extending parallel to the base element rotational axis.

42. The device according to claim 41, characterized in that the amount of centrifugal acceleration acting on the starting material is at least equal to the amount of gravitational acceleration, preferably at least 1.5 times, further preferably at least twice the amount of gravitational acceleration.

43. The device according to claim 41, characterized by focus adjustment means for adjusting a focus of the energy beam.

44. The device according to claim 41, characterized in 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 extracting a gas or waste products are arranged within a base element interior space which is traversed by the base element rotational axis and at least partially surrounded by the base surface or can be arranged therein for the operation of the device.

45. The device according to claim 44, characterized in 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 extracting a gas or waste products are axially and/or radially displaceable.

46. The device according to claim 45, characterized in 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 extracting a gas or waste products are rotatably or pivotably supported.

47. The device according to claim 41, characterized in that in a sectional plane perpendicular to the base element rotational axis, the base surface concentrically encloses the base element rotational axis at least on the majority of the circumference.

48. The device according to claim 47, characterized in that the base surface has the shape of a cylindrical surface at least in a partial region extending in a direction parallel to the base element rotational axis and at least on the majority of the circumference.

49. The device according to claim 41, characterized in that the base element has at at least one axial end a movable and/or removable end wall extending from the base surface in the direction of the base element rotational axis.

Description

[0071] The Figures show the following, schematically and in partial representation:

[0072] FIG. 1: An axial cross-section of a first embodiment of a selective laser melting system,

[0073] FIG. 2: a lateral cross-section of a second embodiment of a selective laser melting system,

[0074] FIG. 3: a third embodiment of a system for selective laser melting with manufacture of a rotationally symmetrical component with internal structures,

[0075] FIG. 4: a fourth embodiment of a selective laser melting system with two laser optics for parallel processing, and

[0076] FIG. 5: a fifth embodiment of a selective laser melting system.

[0077] The Figures do not show the respective system for selective laser melting in its entirety, but are limited in each case to the components essential to the invention. In particular, the systems are also equipped with drive means, control units and feed devices for laser radiation and starting material.

[0078] FIG. 1 shows schematically an axial cross-section of a first embodiment 1 of a system for selective laser melting (hereinafter referred to as first LPBF system 1 for short). The first LPBF system 1 has a base element 2, of which only a base surface 3 in the shape of a hollow cylinder can be seen in the representation of FIG. 1.

[0079] 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-fit or force-fit manner. As an example, a powder 4 is used here as the starting material for additive manufacturing, which is applied to the base surface 3 using a powder applicator 5. Due to the rotational movement, the direction of which is shown by an arrow, about a base element rotational axis, which is perpendicular to the drawing plane, and the centrifugal acceleration which accompanies it, the powder 4 remains on the base surface 3. A powder bed 7 is created by the application of powder. The powder applicator 5 can be moved in the circumferential direction relative to the base element 3, e.g. by the rotation of the base element 2 alone, or additionally by separate drive means not shown here.

[0080] A scraper 6 ensures uniform distribution of the powder 4. An energy beam in the form of a laser beam 8 is irradiated onto the powder bed 7 via laser optics 9. The laser beam 8 selectively melts the powder in the powder bed 7 in one layer, wherein the lateral layer dimensions of the component to be produced are determined by a movement of the laser beam 8 and the layer thicknesses are determined by the height of the respective new powder layer. As the molten layer cools, the material solidifies to form a first layer of a desired component 10, which is built successively in this way. Correct focusing of the laser beam 8 on the powder bed can be achieved by changing the laser optics 9 or by moving the laser optics 9 relative to the base element rotational axis. The displacement of the laser optics 9 can, for example, take place via a first linear axis 11.

[0081] The laser optics 9 can also be moved in other directions, for example via a second linear axis, not shown here, parallel to the base element rotational axis. Alternatively, the laser optics can extend over the entire axial length required for manufacturing the component or act on a corresponding distance by means of a scanner unit not shown separately here, so that it is not necessary to displace the laser optics 9 parallel to the base element rotational axis.

[0082] The laser optics are supported in such a way that they can be rotated about an energy beam rotational axis parallel, preferably coaxial, to the base element rotational axis, as explained in more detail in FIG. 5 with reference to a further embodiment example.

[0083] An inert gas applicator 12 is used to emit an inert gas in the additive manufacturing area, which is collected by means of a gas collector 13. It is apparent that the application of the powder 4 and the manufacture of the component 10 can take place simultaneously.

[0084] The gas stream emitted by the inert gas applicator 12 can also assist or even cause the distribution and smoothing of the powder 4 in the powder bed 7, so that the scraper 6 can be dispensed with.

[0085] The inert gas applicator 12, the gas collector 13 and/or the powder applicator 5 can be radially and/or axially movable. The radial movability is helpful for adapting to the growing component. The axial movability can be used to adapt to a processing area that is being displaced in the axial direction. However, the inert gas applicator 12, the gas collector 13, and/or the powder applicator 5 can also extend in the axial direction over the entire processing area.

[0086] The laser optics 9, the inert gas applicator 12, the gas collector 13 and/or the powder applicator 5 can rotate, pivot or move on a circular or spiral path synchronously, i.e. with an angular velocity identical to that of the base element 2, in order to follow the processing location, for example on the component 10. In this case, the laser optics 9 can be operated continuously. However, it is also conceivable, for example, to temporarily not rotate the laser optics 9 about its energy beam rotational axis or to rotate it at an angular velocity deviating from the angular velocity 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 impacts on the powder bed 7 only in the region of the layers to be manufactured of the component 10, In this case, pulsed or intermittent operation of the laser is indicated.

[0087] FIG. 2 schematically shows a cross-section of a second LPBF system 14 with a base element 16 which has a base surface 15 in the shape of a hollow cylinder, is drum-shaped and has a drive socket 17 for the engagement of a drive element for the base element 16, which drive element is not shown here. In addition to a bottom piece 18 and the circumferential 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. Outside the base element 16, a radial linear guide 27 is provided for the laser optics 22. The radial linear guide 27 may alternatively 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 supporting and driving a rotation of the laser optics 22, which means are also not shown.

[0088] Further elements, such as a powder applicator or an inert gas applicator, are not shown in FIG. 2 for the sake of clarity, but they can also be inserted via the opening 21 and their spatial position can be changeable, for example, via linear guides or via rotation or pivoting axes.

[0089] The second LPBF system 14 shown is used, for example, to manufacture two components 24 and 25, which can be closed in the circumferential direction of the base element 16 and each have an annular shape, for example.

[0090] FIG. 3 schematically shows a cross-section of a base element 29 with base surface 30 of a third LPBF system 26, wherein the base element 29 rotates in the direction of the arrow. Laser optics 31 are arranged in the base element 29, by means of which an annularly closed component 33 with cavities 34 is produced by additive manufacturing from a powder bed 32, only one of which cavities is provided with a reference number. The energy beam rotational axis (see 46 for the fourth embodiment in FIG. 4) for the laser optics 31 is not shown here.

[0091] FIG. 4 schematically shows a cross-section of a base element 35 with base surface 36 of a fourth LPBF system 37, wherein the base element 35 rotates about the base element rotational axis in the direction of the arrow.

[0092] First laser optics 38 and second laser optics 39 are arranged in the base element 35, which laser optics simultaneously apply laser radiation 41 to different locations of a powder bed 40 for simultaneous layer formation on two different components 42 and 43. The first laser optics 38 and the second laser optics 39 may be rotated about the energy beam rotational axis 46 coaxial to the base element rotational axis, and the angular velocity of the laser optics 38 and 39 may at times be identical to or deviate from that of the base element 35 to change the orientation of the laser beams 41 relative to the base element 35. When the base element 35, with respect to its angular position relative to the laser optics 38 and 39, has rotated further by a suitable angle, the laser optics 38 and 39 can simultaneously apply respectively one layer to two other components 44 and 45. By means of the two laser optics 38 and 39, a component further expanding in the circumferential direction, in particular a component that is closed in the circumferential direction, can also be processed simultaneously at different locations. Means for applying the powder and/or for streaming an inert gas, which are not shown here, can also be provided multiple times—for example, corresponding to the number of laser optics 38, 39.

[0093] FIG. 5 shows a fifth LPBF system 50 with a base element 51 having a base surface 52. A powder to be used as starting material for additive manufacturing is not shown. The base element 51 is driven by means to rotate at an angular velocity ω1, symbolized by the arrow 53, which means are not shown here. The drive can, for example, engage the outside of the base element 51 in a form-fit or force-fit manner. Via a support 54, a hollow shaft 55 is guided into the interior of the base element 51. The support allows both rotational movement and axial displacement, indicated by the double arrow, between the base element 51 and the hollow shaft 55. Via drive means not shown here, the hollow shaft 55 is driven to rotate at the angular velocity ω2, symbolized by the arrow 56.

[0094] 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 allows the radiation source, which is not shown, to be operated without rotary movement.

[0095] An optical component 59, symbolized here only by three optical lenses 60, is connected upstream of the rotary coupling 57 in the beam direction, with which a controlled focus adjustment for the laser beam 58 is possible.

[0096] The hollow shaft 55 has a mirror element 61 at its front end, which in the example shown is supported for 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 also 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 changing the angle of inclination of the mirror element 61 accordingly, or in the case of a mirror element with a fixed deflection angle, by axial displacement. Of course, alternative optical deflection devices, such as a prism, can be used instead of a mirror. As the thickness of the powder layer changes, the focus position can be adjusted using the optical component 59.

[0097] The angular velocity ω2 56 of the hollow shaft 55 corresponds to the angular velocity at which the laser beam 58 rotates about its energy beam rotational axis, here coinciding with the central longitudinal axis of the hollow shaft 55. The angular velocity ω2 56 of the hollow shaft 55 can coincide with the angular velocity ω1 53 of the base element 51, so that the energy beam 58 on one side and the base surface 52 or, respectively, the surface of a powder layer not shown here on the other side have no relative movement with respect to one another at the point of impact of the laser beam 58, if one disregards a scanning movement controlled by the mirror 61.

[0098] It is advantageous to select different angular velocities ω2 56 of the hollow shaft 55 and ω1 53 of the base element 51 so that, disregarding any scanning movement of the laser beam 58, there is a relative velocity between the impacting laser beam 58 and the surface of the powder layer.

[0099] This relative velocity determines the speed of the process progress and is e.g. at least 100 mm/s, typically 200 mm/s and up to 2 m/s or also up to max. 5 m/s. The relative movement can be achieved with ω2>ω1 or with ω2<ω1. The relative movement can also be achieved by the hollow shaft 55 and base element 51 having opposite rotational directions.

[0100] The relative velocity does not have to be constant during the manufacturing process, but can also be changed. For example, different relative velocities can be provided at different axial positions.

[0101] In additive manufacturing, components are manufactured in successive layers. Different relative velocities can be provided for different layers of the component. In addition, local variation of the intensity of the laser beam is possible for different axial positions and different layers.

[0102] All of the embodiment examples presented can be suitably varied with respect to the number of elements presented, such as laser optics, components, powder applicators, scrapers, inert gas applicators, and/or gas collectors. Instead of powder, an alternative starting material, such as a viscous starting material, e.g. a liquid, is also conceivable as a starting material in the embodiments shown. In addition, alternative energy radiation, for example electron radiation or ultraviolet radiation (UV radiation), can be used instead of laser radiation.

TABLE-US-00001 Reference symbol list 1 First LPBF system 2 Base element 3 Base surface 4 Powder 5 Powder applicator 6 Scraper 7 Powder bed 8 Laser beam 9 Laser optics 10 Component 11 First linear axis 12 Inert gas applicator 13 Gas collector 14 Second LPBF system 15 Base surface 16 Base element 17 Drive socket 18 Bottom piece 19 Circumferential wall 20 Front end wall 21 Opening 22 Laser optics 23 Axial linear guide 24 Component 25 Component 26 Third LPBF system 27 Radial linear guide 28 Feed line 29 Base element 30 Base surface 31 Laser optics 32 Powder bed 33 Component 34 Cavity 35 Base element 36 Base surface 37 Fourth LPBF system 38 First laser optics 39 Second laser optics 40 Powder bed 41 Laser radiation 42 Component 43 Component 44 Component 45 Component 46 Energy beam rotational axis 50 Fifth LBPF system 51 Base element 52 Base surface 53 Arrow 54 Support 55 Hollow shaft 56 Arrow 57 Rotary coupling 58 Laser radiation 59 Optical component 60 Optical lens 61 Mirror element