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CN-115135436-B - Exposure strategy associated with laser centers

CN115135436BCN 115135436 BCN115135436 BCN 115135436BCN-115135436-B

Abstract

The invention relates to a method for controlling an energy input device (20) of an additive manufacturing apparatus for manufacturing a three-dimensional object with the additive manufacturing apparatus, each beam of a number of beams being assigned a beam deflection center (23) above a build plane (7), from which beam deflection center the beam is directed towards the build plane (7), each beam deflection center (23) being assigned a projection center (23 '), which projection center corresponds to a perpendicular projection of the position of the beam deflection center (23) onto the build plane (7), the direction of the motion vector of the number of beams (22) at the time of scanning a trajectory (54) being defined, at least in a section of the object cross-section, such that at each curing point in the section the motion vector has an angle smaller than a predetermined maximum angle gamma 1 with respect to a connection vector from the curing point to the projection center (23') of the beam (22) used.

Inventors

  • S. BRANDT
  • A. FREY

Assignees

  • EOS有限公司电镀光纤系统

Dates

Publication Date
20260505
Application Date
20210217
Priority Date
20200218

Claims (20)

  1. 1. A method for controlling an energy input device (20) of an additive manufacturing apparatus for manufacturing a three-dimensional object using the additive manufacturing apparatus, Wherein the object is manufactured with the additive manufacturing apparatus by applying build material layer by layer and by curing the build material in a build plane (7), curing of the build material being achieved with energy input means by supplying radiation energy to curing points in each layer assigned to a cross section of the object in the layer in such a way that the curing points are scanned along a plurality of trajectories (54) in the build plane (7) with a number of beams (22) provided by the energy input means (20), Each of the number of beams being distributed over a beam deflection center (23) above the build plane (7) from which beam deflection center the beam is directed towards the build plane, Each beam deflection center (23) being assigned a projection center (23') corresponding to a perpendicular projection of the position of the beam deflection center (23) on the building plane (7), At least one section of the cross-section of the object is solidified sub-area by sub-area, In at least one of the sub-areas (53), the solidification point of the sub-area is scanned with a beam (22) assigned to the sub-area, the scanning order of the trajectories (54) is defined such that the trajectory closer to the projection center (23 ') of the beam is scanned before the trajectory further from the projection center (23'), and The temporal sequence of scanning the sub-regions (53) is defined such that sub-regions closer to the projection center (23 ') of the beam (22) are scanned before sub-regions farther from the projection center (23'), the solidification points of which are assigned to the beam scanning of these sub-regions.
  2. 2. Method according to claim 1, wherein in the sub-region (53) in which the trajectories (54) extend substantially parallel to each other and the order of scanning the trajectories is defined such that trajectories closer to the projection center (23 ') of the beam (22) are scanned before trajectories further away from the projection center (23 '), the direction of the motion vector along the trajectory is defined such that at each of said solidification points the motion vector has an angle smaller than a predetermined maximum angle y 1 with respect to a connection vector from the solidification point to the projection center (23 ') of the beam (22) for the sub-region.
  3. 3. Method according to claim 1 or 2, wherein, for determining the proximity of a track to a projection center (23 '), a reference point connection vector (83) from a reference point on the respective track to the projection center (23 ') is established for each of the tracks, and the length of a component (83 s) of the reference point connection vector (83) perpendicular to the track is determined, wherein it is provided that for each two tracks of different lengths of the component (83 s) perpendicular to the track, the track of smaller length of the component (83 s) perpendicular to the track is closer to the projection center (23 ') of the beam (22).
  4. 4. Method according to claim 1 or 2, wherein in a sub-region (53) in which the trajectories (54) extend substantially parallel to each other and the order of scanning the trajectories is defined such that the trajectory closer to the projection center (23 ') of the beam (22) is scanned before the trajectory further away from the projection center (23 '), the motion vector at least one solidification point has an angle with respect to the connection vector from the solidification point to the projection center (23 ') of the beam (22) used that is larger than a predetermined minimum angle γ2.
  5. 5. The method according to claim 4, wherein different minimum angles γ2 are specified for different values of the beam deflection angle α, wherein the beam deflection angle is defined as the arctangent of the quotient of the distance from the solidification point to the projection center (23 ') and the length of the projection line (23 k) of the beam deflection center (23), the projection line (23 k) of the beam deflection center (23) being the perpendicular to the building plane (7) connecting the projection center (23') with the beam deflection center (23).
  6. 6. Method according to claim 1 or 2, wherein the air flow is directed through the respective curing points during scanning when manufacturing a three-dimensional object with the additive manufacturing apparatus, Wherein, for scanning a solidification point in said at least one of said sub-areas (53), a beam deflection center (23) is selected for which a directional component of said gas flow is directed from said solidification point to a projection center (23') assigned to said beam deflection center (23).
  7. 7. A method for controlling an energy input device (20) of an additive manufacturing apparatus for manufacturing a three-dimensional object using the additive manufacturing apparatus, Wherein the object is manufactured with the additive manufacturing apparatus by applying build material layer by layer and by curing the build material in a build plane (7), curing of the build material being achieved with energy input means by supplying radiation energy to curing points in each layer assigned to a cross section of the object in the layer in such a way that the curing points are scanned along a plurality of trajectories (54) in the build plane (7) with a number of beams (22) provided by the energy input means (20), Each of said number of beams being distributed over a beam deflection center (23) above the build plane (7), from which beam deflection center the beam is directed towards the build plane (7), Each beam deflection center (23) being assigned a projection center (23') corresponding to a perpendicular projection of the position of the beam deflection center (23) on the building plane (7), At least in a section of the cross-section of the object, the direction of the motion vectors of the beams (22) in scanning the trajectory (54) is defined such that at each solidification point in the section the motion vector has an angle smaller than a predetermined maximum angle gamma 1 with respect to the connection vector from the solidification point to the projection centre (23') of the beam (22) used, and At least one section of the cross-section of the object is solidified sub-area by sub-area, wherein the temporal sequence of scanning sub-areas (53) is defined such that sub-areas closer to the projection center (23 ') of the beam (22) are scanned before sub-areas farther from the projection center (23'), the solidification points of said sub-areas being allocated to the beam scanning of these sub-areas.
  8. 8. The method of claim 7, wherein the predetermined maximum angle γ1 has a value of less than or equal to 135 °.
  9. 9. The method according to claim 7, wherein different maximum angles γ1 are specified for different values of the beam deflection angle α, wherein the beam deflection angle is defined as the arctangent of the quotient of the distance between the solidification point and the projection center (23 ') and the length of the projection line (23 k) of the beam deflection center (23), the projection line (23 k) of the beam deflection center (23) being the perpendicular to the building plane (7) connecting the projection center (23') with the beam deflection center (23).
  10. 10. The method of claim 7 or 8, wherein at least two adjacent tracks (54) are scanned in the same or different directions and adjacent tracks are scanned using different beams (22).
  11. 11. Method according to claim 7 or 8, wherein the air flow is directed through the respective curing points during scanning when manufacturing a three-dimensional object with the additive manufacturing apparatus, Wherein in said at least one section of the object cross-section, the direction of the motion vector of said number of beams (22) when scanning the trajectory (54) is defined such that one directional component of the air flow is opposite to the direction of the motion vector of said number of beams.
  12. 12. The method of claim 7, wherein the predetermined maximum angle γ1 has a value of less than or equal to 90 °.
  13. 13. A method for controlling an energy input device (20) of an additive manufacturing apparatus for manufacturing a three-dimensional object using the additive manufacturing apparatus, Wherein the object is manufactured with the additive manufacturing apparatus by applying build material layer by layer and by curing the build material in a build plane (7), curing of the build material being achieved with energy input means by supplying radiation energy to curing points in each layer assigned to a cross section of the object in the layer in such a way that the curing points are scanned along a plurality of trajectories (54) in the build plane (7) with a number of beams (22) provided by the energy input means (20), Each of the number of beams being distributed over a beam deflection center (23) above the build plane (7) from which beam deflection center the beam is directed towards the build plane (7), Each beam deflection center (23) being assigned a projection center (23') corresponding to a perpendicular projection of the position of the beam deflection center (23) on the building plane (7), At least one section of the cross-section of the object is solidified sub-area by sub-area, wherein the temporal sequence of scanning sub-areas (53) is defined such that sub-areas closer to the projection center (23 ') of the beam (22) are scanned before sub-areas farther from the projection center (23'), the solidification points of said sub-areas being allocated to the beam scanning of these sub-areas.
  14. 14. Method according to claim 13, wherein in the sub-region (53) defining the temporal sequence of the scan, the motion vector at each of said solidification points has an angle smaller than a predetermined maximum angle γ1 with respect to a connection vector from the solidification point to the projection center of the beam for that sub-region.
  15. 15. Method according to claim 13 or 14, wherein the minimum value of the distance of the solidification points in a sub-area to the centre of projection is used as a measure of the distance of the sub-area (53) to the centre of projection (23').
  16. 16. Method according to claim 13 or 14, wherein the section has a plurality of sub-areas (53) which have a rectangular shape in a top view onto the building plane (7), the tracks (54) in the section extending substantially parallel to each other and to the lateral sides of the sub-areas, wherein the length of a perpendicular (93 p) from the projection center to a straight line extending through the sub-areas parallel to the longitudinal sides of the sub-areas is used as a measure of the distance of the sub-areas (53) to the projection center (23').
  17. 17. The method of claim 16, wherein upon curing a cross-section of the object present in a different layer, longitudinal sides of the plurality of sub-regions in the different layer have an orientation that changes in a build plane.
  18. 18. Method according to claim 13 or 14, wherein in each of the sub-areas (53) defining the temporal sequence of the scanning, the motion vector at the solidification point has an angle larger than a predetermined minimum angle γ2 with respect to a straight line connecting the solidification point to the projection center of the beam used.
  19. 19. Method according to claim 13 or 14, wherein the air flow is directed through the respective curing points during scanning when manufacturing a three-dimensional object with the additive manufacturing apparatus, Wherein, in order to scan a solidification point in said at least one section of an object cross-section, a beam deflection center (23) is selected for which a directional component of the gas flow is directed from the solidification point to a projection center (23') assigned to the beam deflection center (23).
  20. 20. The method according to claim 1 or 7 or 13, wherein the method is carried out for a section having at least one solidification point, the beam deflection angle exceeding a deflection minimum angle α1 when scanning the at least one solidification point, wherein the beam deflection angle is defined as the arctangent of the quotient of the distance of the solidification point to the projection center (23 ') and the length of a projection line (23 k) of the beam deflection center (23), wherein the projection line (23 k) of the beam deflection center (23) is a perpendicular to a construction plane (7) connecting the projection center (23') with the beam deflection center (23).

Description

Exposure strategy associated with laser centers Technical Field The present invention relates to a method for controlling an energy input device of an additive manufacturing apparatus, a correspondingly adapted additive manufacturing method, a corresponding apparatus for controlling an energy input device of an additive manufacturing apparatus, a correspondingly adapted additive manufacturing apparatus and an object produced by the correspondingly adapted additive manufacturing method. The additive manufacturing apparatus and related methods to which the present invention relates are generally characterized in that they manufacture objects layer by solidifying amorphous build material (e.g., metal powder or plastic powder). Solidification may be achieved, for example, by supplying thermal energy to the build material by irradiating it with electromagnetic radiation or particle radiation, such as laser sintering (SLS or DMLS) or laser melting or electron beam melting. For example, in laser sintering or laser melting, a laser beam is moved through points of a layer of build material corresponding to the cross-section of an object to be fabricated in the layer, such that the build material solidifies at these points. After melting or sintering the build material at one point by supplying thermal energy, the build material is no longer in an amorphous state after cooling, but is present as a solid. After scanning all points of an object cross-section to be cured, a new layer of build material is applied and cured at the same point corresponding to the object cross-section in that layer. Background Particularly in the processing of metal powders as building materials, impurities (for example metal vapors, fumes or splashes) are produced during the melting process, which deposit on the layer to be solidified or interfere with the supply of radiation. These impurities are undesirable because they may lead to an undesirable distribution of, for example, the mechanical properties of the produced object. Accordingly, in the prior art, attempts have been made to minimize the effect of these impurities on the properties of the manufactured object by passing a gas stream through the points to be solidified during scanning. WO2014/125280A2 proposes to match the direction of movement of the beam with the direction of the air flow when scanning the layer in order to obtain as uniform object properties as possible. Although this approach has improved the performance of the object, the approach still needs improvement, because on the one hand the coordination of the beam movement and the gas flow direction sometimes complicates the manufacturing process, and on the other hand non-uniformities in the performance of the object are still observed, especially in the case of large-area building areas. Disclosure of Invention It is therefore an object of the present invention to provide a method and an apparatus for controlling an energy input device of an additive manufacturing apparatus by means of which an improved uniformity of properties of an additive manufactured object can be achieved. This object is achieved by a method for controlling an energy input device according to claims 1,5 and 10, an additive manufacturing method according to claim 24, an apparatus for controlling an energy input device according to claims 25, 26 and 27, an additive manufacturing apparatus according to claim 28 and an object according to claim 29. In particular, the device according to the invention can be further developed by the features of the method according to the invention, which are set forth below or in the dependent claims, and vice versa. Furthermore, features described in connection with one device according to the invention may also be used for further developments of another device according to the invention, even if this is not explicitly stated. The present invention relates to additive manufacturing apparatus and methods, in particular to such apparatus and methods, in which energy in the form of electromagnetic radiation or particle radiation is selectively supplied to an amorphous build material layer. The working plane (also called the build plane) is the plane in which the upper side of the layer to which energy is supplied is located. In this case, the energy input means may comprise, for example, a laser or an electron beam source. The radiation provided to the build material heats the build material, causing a sintering or melting process. In particular, the present invention relates to laser sintering, laser melting and electron beam melting apparatus and related methods. Although the invention is applicable to both plastic-based and metal-based build materials, it is particularly advantageous that the invention is applied to additive manufacturing methods and apparatus using metal or at least metal-containing build materials, such as metal powders or metal alloy powders. In this connection, it should be noted that with t