Exposure strategies related to laser centers

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 of several beams is assigned a beam deflection center (23) above a build plane (7), the beams are aimed at the build plane (7) from the beam deflection centers, each beam deflection center (23) is assigned a projection center (23'), which corresponds to the perpendicular projection of the position of the beam deflection center (23) on the build plane (7), the direction of the movement vector of the several beams (22) in a section of the object cross section is defined in such a way that, at each solidification point in the section, the movement vector has an angle to the connection vector from the solidification point to the projection center (23') of the used beam (22) which is smaller than a predetermined maximum angle γ1.

Description

Technical Field

[0001] The present invention relates to a method for controlling an energy input device for an additive manufacturing equipment, a corresponding additive manufacturing method, a corresponding device for controlling the energy input device for an additive manufacturing equipment, a corresponding additive manufacturing equipment, and an object produced by the corresponding additive manufacturing method.

[0002] The additive manufacturing equipment and related methods of the present invention are generally characterized in that they manufacture objects layer by layer by solidifying amorphous building materials (e.g., metal powder or plastic powder). Solidification can be achieved, for example, by supplying thermal energy to the building material by irradiating it with electromagnetic radiation or particle radiation (e.g., laser sintering (SLS or DMLS) or laser melting or electron beam melting). For example, in laser sintering or laser melting, a laser beam moves through the building material layer to those points corresponding to the cross-section of the object to be manufactured in that layer, causing the building material to solidify at those points. After the building material is melted or sintered at a point by supplying thermal energy, the building material, upon cooling, is no longer in an amorphous state but exists as a solid. After scanning all the points to be solidified on a cross-section of an object, a new layer of building material is applied and similarly solidified at the points corresponding to the cross-section of the object in that layer. Background Technology

[0003] Especially when processing metal powders used as building materials, impurities (such as metal vapor, fumes, or spatter) are generated during the melting process. These impurities deposit on the layer to be cured or interfere with the supply of radiation. These impurities are undesirable because they can lead to undesirable distributions of, for example, the mechanical properties of the produced object. Therefore, in the prior art, attempts are made to minimize the impact of these impurities on the properties of the manufactured object by passing the airflow through the point to be cured during the scanning process.

[0004] WO2014 / 125280A2 proposes matching the beam motion direction with the airflow direction during scanning to obtain the most uniform object properties possible. Although this method has improved object performance, it still needs improvement because, on the one hand, coordinating the beam motion and airflow direction can sometimes complicate the manufacturing process, and on the other hand, non-uniformity in object properties is still observed, especially in the case of large-area construction areas. Summary of the Invention

[0005] Therefore, the object of the present invention is to provide a method and apparatus for controlling the energy input device of an additive manufacturing equipment, by means of which improved uniformity of the properties of additively manufactured objects can be achieved.

[0006] This objective is achieved by the method for controlling an energy input device according to claims 1, 5, and 10; the additive manufacturing method according to claim 24; the apparatus for controlling an energy input device according to claims 25, 26, and 27; the additive manufacturing apparatus according to claim 28; and the object according to claim 29. In particular, the apparatus according to the invention can be further developed by 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 conjunction with one apparatus according to the invention can also be used for further development of another apparatus according to the invention, even if not explicitly stated.

[0007] The additive manufacturing apparatus and methods of the present invention are particularly those in which energy in the form of electromagnetic radiation or particle radiation is selectively supplied to an amorphous building material layer. The working plane (also called the building plane) is the plane on which the upper side of the layer to which energy is supplied lies. In this case, the energy input device may include, for example, a laser or an electron beam source. The radiation supplied to the building material heats the building material, thereby inducing 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 building materials, it is particularly advantageous for additive manufacturing methods and apparatus using metal or at least metal-containing building materials (e.g., metal powder or metal alloy powder).

[0008] In this respect, it should be noted that, with the aid of the additive manufacturing apparatus according to the invention, not only can one object be manufactured, but several objects can be manufactured simultaneously. If the manufacture of objects is mentioned in this application, it goes without saying that the corresponding description can also be applied in the same manner to the additive manufacturing method and apparatus in which several objects are manufactured simultaneously.

[0009] Here, the term "beam" is used instead of "ray" to indicate that the diameter of the ray does not have to be very small, especially when the radiation is incident obliquely on the building material, or when radiation is used to intentionally cover a large surface area when incident on the building material.

[0010] The beam deflection center can be, for example, a scanner with one or more galvanometer mirrors for deflecting the laser beam. Multiple different beams can also be assigned to the same beam deflection center or scanner, for example, by alternately aligning the beams from that beam deflection center to the construction plane, although typically one beam deflection center is assigned exactly one beam to be guided onto the construction plane. It should be noted that in this application, the term "several" is always understood to mean "one or more". To project the position of the beam deflection center onto the construction plane, a perpendicular line can be established, for example, passing through a point on the beam deflection center from which the beam pointing towards the construction plane begins. The projection center is the location on the construction plane where the perpendicular line is established. It should be mentioned that in the case of multiple beams assigned to a single beam deflection center, the possible differences in the positions of the beam origins are negligible.

[0011] In the method according to the invention, in order to manufacture at least several cross-sections of an object, preferably for manufacturing the entire object, in each case, an energy input device is controlled based on a data model of the object's cross-sections, such that the energy required for curing the building material is supplied to the points to be cured corresponding to the object's cross-sections via the energy input device. Specifically, the temporal sequence of the points to be cured is determined, i.e., a scan line or trajectory in the building plane along which the beam should move, and correspondingly, several control beam deflection centers are established to move the beams assigned to them.

[0012] The beam trajectory specified when controlling the energy input device corresponds to a solidification path in the building plane. By moving the molten pool in a direction substantially parallel to the building plane, the building material is solidified along this solidification path. Here, the beam provides so much energy at the solidification point to the preferably powdery or paste-like building material that the building material sintersulates or completely melts at that point due to exceeding the melting temperature, i.e., the solidus temperature and / or liquidus temperature, so that the building material no longer exists in an amorphous state in the cooled state, but exists as a solid. Therefore, the solidification path is a region in which the solidification of the building material is actually achieved, rather than merely heated, during the scanning of the building material by the at least one beam. For example, the solidification path can be a straight route with a certain width, but there are also cases where one or more directional changes occur when the beam is moved along the solidification path, particularly where the solidification path is geometrically presented as a curve with a certain width. In this application, when referring to scanning with a beam, this always refers to the effect of the beam on the building material that results in the solidification of at least the uppermost layer of the building material, i.e., it is not merely a preheated or post-heated building material.

[0013] When referring to the angle between two vectors in this application, it always means that the value of the angle between the directions of the two vectors is less than or equal to 180°.

[0014] The section of the cross-section of an object referred to in this invention does not necessarily refer only to a portion of the cross-section of an object or a single cross-section of an object, but may also include the entire object to be manufactured.

[0015] In the method according to the invention for controlling the energy input device of an additive manufacturing equipment to manufacture a three-dimensional object using the additive manufacturing equipment, the object is manufactured by applying building material layer by layer and by the building material being solidified in a building plane. The solidification of the building material is achieved by the energy input device by supplying radiant energy to solidification points in each layer that are assigned to the cross-section of the object in that layer. The radiant energy is supplied by scanning these solidification points along multiple trajectories in the building plane using a plurality of beams provided by the energy input device.

[0016] Each of the plurality of beams is assigned a beam deflection center above the construction plane, and the beam is aligned with the construction plane from the beam deflection center.

[0017] Each beam deflection center is assigned a projection center, which corresponds to the vertical projection of the beam deflection center's position onto the construction plane.

[0018] In at least one segment of the cross-section of the object, the direction of the motion vectors of the plurality of beams in the scanning trajectory is defined such that at each solidification point in that segment, the motion vector has an angle relative to the connecting vector from the solidification point to the projection center of the beam used, the angle being less than a predetermined maximum angle γ1.

[0019] The connection vector from the solidified point to the projection center is here a vector pointing towards the projection center along the shortest possible straight line connecting the solidified point and the projection center, the length of which corresponds to the distance between the solidified point and the projection center.

[0020] The method according to the invention enables additive manufacturing of objects with improved uniformity. This applies not only to the uniformity of material properties within the object but also to the reproducibility of properties between objects when the same objects are manufactured simultaneously at multiple different locations within an additive manufacturing apparatus. The inventors explain this by the fact that during the manufacturing process, the beam is almost always incident on the build plane at an angle other than 90°. In fact, vertical incidence of the beam exists only at the projection center. According to the inventors, oblique incidence of the beam causes displacement of the build material at the solidification point. Therefore, the inventors observed that, with oblique incidence of the beam, the more significantly the beam's movement moves away from the projection center, the more build material is displaced. This displacement of the build material leads to fluctuations in the volume of the solidified material, resulting in non-uniformity of mechanical properties. Therefore, avoiding beam movement directions that are substantially away from the projection center provides an advantage. In particular, these advantages are independent of the corresponding orientation of the airflow through the build area relative to the beam's motion vector.

[0021] It should be noted that different maximum angle γ1 values ​​can also be defined for motion vectors located on different sides of the connecting vector.

[0022] Preferably, the value of the predetermined maximum angle γ1 is less than or equal to 135°, and more preferably less than or equal to 90°.

[0023] To obtain good results, a maximum angle of 90° is preferred. However, satisfactory results can still be obtained using a maximum angle between 90° and 135°. The smaller the maximum angle, the better the results. Therefore, depending on the quality requirements, maximum angles such as 75°, 60°, and 45° can also be selected.

[0024] More preferably, 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 and the length of the projection line of the beam deflection center, the projection line of the beam deflection center being a perpendicular line to the construction plane, which connects the projection center and the beam deflection center.

[0025] Here, the beam deflection angle α is defined as the angle between the beam propagation direction and the perpendicular line to the building plane. The more obliquely the beam is incident on the building plane, i.e., the larger the beam deflection angle α, the more pronounced the effect of the beam incident on the building material (especially material displacement) will be, and the smaller the maximum angle γ1 should be. Therefore, it is advantageous to use a smaller maximum angle γ1 as a basis in the region farther away from the projection center of the beam deflection center. It is already advantageous to base it on at least two different values ​​of the maximum angle γ1, where, of course, classifying the maximum angle γ1 into three, four, or five different values ​​according to the beam deflection angle α will lead to better results.

[0026] More preferably, the method specifies that at least two adjacent trajectories are scanned in the same or different directions, and different beams are used to scan the adjacent trajectories.

[0027] The advantages of this method are particularly evident when multiple different beams are assigned to multiple different beam deflection centers. The scanning process can then be performed more quickly because, regardless of whether it is temporally advantageous to scan multiple different points on the cross-section of the object simultaneously, for each solidified point, a beam can always be selected for scanning, positioned advantageously for implementing the preferred exposure method due to the location of the relevant projection center. In particular, adjacent trajectories can then be scanned in alternating directions, which can be performed with an increased time offset if necessary.

[0028] When manufacturing three-dimensional objects using additive manufacturing equipment, airflow can be passed through corresponding solidification points during scanning. Preferably, in at least one segment of the object's cross-section, the direction of the motion vectors of the plurality of beams along the scanning trajectory is defined such that a directional component of the airflow is opposite to the direction of the motion vectors of the plurality of beams.

[0029] Specifically, the angle between each motion vector and the airflow direction can be greater than 90°, preferably greater than 135°, and more preferably greater than 150°. Ideally, the airflow direction is exactly opposite to the direction of the motion vector.

[0030] Therefore, by additionally taking into account the direction of airflow, the results achievable by the present invention can be further improved.

[0031] In another method according to the invention for controlling an energy input device for an additive manufacturing equipment to manufacture a three-dimensional object using the additive manufacturing equipment, the object is manufactured by applying building material layer by layer and by solidifying the building material in a building plane. The solidification of the building material is achieved by the energy input device supplying radiant energy to solidification points in each layer, which are assigned to cross-sections of the object within that layer. The radiant energy is supplied by scanning these solidification points along multiple trajectories in the building plane using several beams provided by the energy input device.

[0032] Each of the plurality of beams is assigned a beam deflection center above the construction plane, and the beam is aligned with the construction plane from the beam deflection center.

[0033] Each beam deflection center is assigned a projection center, which corresponds to the vertical projection of the beam deflection center's position onto the construction plane.

[0034] Solidify at least one segment of the object's cross-section, sub-region by sub-region.

[0035] In at least one of the sub-regions, the solidified point of the sub-region uses the beam scan assigned to the sub-region to define the scanning order of the trajectory such that the trajectory closer to the projection center of the beam is scanned before the trajectory farther away from the projection center.

[0036] In principle, the mentioned sub-regions can have any shape. Preferably, rectangular or square shapes are chosen because the tracks in such a sub-region typically have the same or substantially the same length, which allows for better uniformity during curing. Two tracks are substantially parallel if they are parallel to each other at least 80%, preferably at least 95%, of the shorter of the two;

[0037] Assuming that the same method for determining the spatial distances of all trajectories within a sub-region is used, there are no restrictions on how the distances are determined. For example, the average distance of all points on a trajectory to the projection center can be defined as the distance of that trajectory to the projection center. However, the minimum distance of all points on a trajectory to the projection center can also be defined accordingly.

[0038] In the method according to the invention, it can result in additively manufactured objects with improved uniformity, an advantage stemming from the fact that the non-isotropic deposition of material is considered when the beam is incident obliquely on the build plane. Specifically, when the beam is incident obliquely, impurities generated during the melting process (e.g., partially melted material) preferentially deposit in the build plane toward the projection center. If a trajectory with a smaller distance to the projection center is scanned before a trajectory with a larger distance to the projection center, this results in trajectories being scanned one after another in a sub-region, starting with the trajectory closest to the projection center and ending with the trajectory furthest from the projection center. This results in impurities that appear during the scanning of the trajectory always being deposited (towards the projection center) on the already solidified build material. This leads to improved uniformity of the solidified object because impurities cannot interfere with the solidification process of subsequent trajectories, which would occur if the scanning order were reversed. In particular, uniformity is improved regardless of the corresponding orientation of the airflow through the build area.

[0039] Preferably, in a sub-region where the trajectories are substantially parallel to each other and the order of scanning the trajectories is defined such that the trajectory closer to the projection center of the beam is scanned before the trajectory farther from the projection center, the direction of the motion vector along the trajectory is defined such that at each solidification point the motion vector has an angle relative to the connecting vector from the solidification point to the projection center of the beam for that sub-region is less than a predetermined maximum angle γ1.

[0040] The described process combines the advantages of favorable selection of the direction of the motion vector during trajectory scanning with the advantages of favorable selection of the scanning sequence of the trajectory, thereby obtaining a more uniform component. For good results, a maximum angle γ1 of 90° is preferably selected. However, satisfactory results can still be obtained even at maximum angles between 90° and 135°. The smaller the maximum angle, the better the results. Therefore, depending on quality requirements, maximum angles such as 75°, 60°, and 45° can also be selected.

[0041] More preferably, in order to determine the proximity of each trajectory to the projection center for each trajectory, a connection vector is established from a reference point on the corresponding trajectory, preferably from the starting point of the corresponding trajectory to a reference point on the projection center, and the length of the component of the reference point connection vector perpendicular to the trajectory is determined, wherein it is stipulated that for every two trajectories with different lengths of the component perpendicular to the trajectory, the trajectory with the smaller length of the component perpendicular to the trajectory is closer to the projection center of the beam.

[0042] Here, a reference point on the trajectory is a point whose distances to the start and end points of the trajectory satisfy a predetermined relationship. Specifically, the reference point can be either the start or end point of the trajectory. For example, if adjacent trajectories are scanned in opposite directions, a point with the same distance to both the start and end points can be defined as a reference point. The described process for determining the distance of the trajectory from the projection center is particularly advantageous if the trajectory is not perpendicular to the connecting vector from the projection center to the corresponding start point of the trajectory.

[0043] More preferably, in a sub-region where the trajectories are substantially parallel to each other and the scanning order of the trajectories is defined such that the trajectory closer to the projection center of the beam is scanned before the trajectory farther from the projection center, the motion vector at at least one fixed point has an angle greater than a predetermined minimum angle γ2 relative to the connecting vector from the fixed point to the projection center of the beam used.

[0044] When the beam's motion vector during scanning has a small angle relative to the connection vector from the solidification point on the trajectory to the projection center, impurities are deposited roughly along the trajectory itself when the beam is incident obliquely on the construction plane. Thus, damage to adjacent trajectories is not significant. Therefore, it is useful to define a minimum angle γ2 and specify a particular order of scanning trajectories only when this minimum angle is exceeded. Preferably, a value of 45° can be chosen for the minimum angle, even more preferably a value of 60°, and even more preferably a value of 75°.

[0045] It should also be noted that different values ​​of the minimum angle γ2 can be specified for motion vectors located on different sides of the connecting vector.

[0046] Preferably, different minimum angles γ2 are specified for different values ​​of 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 and the length of the projection line of the beam deflection center, wherein the projection line of the beam deflection center is a perpendicular line to the construction plane, which connects the projection center and the beam deflection center.

[0047] The more obliquely the beam is incident on the construction plane, the more pronounced the deposition of impurities in the preferred direction will be. Therefore, it is advantageous to use a smaller minimum angle γ2 as a basis in the region further away from the projection center of the beam deflection center. Here, it is already advantageous if at least two different values ​​of the minimum angle γ2 are used as a basis.

[0048] When manufacturing three-dimensional objects using additive manufacturing equipment, airflow can be passed through corresponding solidification points during scanning. Preferably, to scan solidification points in at least one of the sub-regions, a beam deflection center is selected such that, with respect to this beam deflection center, a directional component of the airflow points from the solidification point to the projection center assigned to that beam deflection center.

[0049] Specifically, the angle between the airflow direction and the connecting line between the solidification point and the projection center can be selected to be less than 90°, preferably less than 45°, and more preferably less than 30°. Ideally, the airflow should be precisely directed towards the projection center.

[0050] Therefore, by taking the direction of airflow into consideration, the results achievable by the present invention can be further improved.

[0051] According to the present invention, in another method for controlling the energy input device of an additive manufacturing equipment to manufacture a three-dimensional object using the additive manufacturing equipment, the object is manufactured by applying building material layer by layer and by the building material being solidified in a building plane. The solidification of the building material is achieved by the energy input device supplying radiant energy to solidification points in each layer that are assigned to the cross-section of the object in that layer. The radiant energy is supplied by scanning these solidification points along multiple trajectories in the building plane using a plurality of beams provided by the energy input device.

[0052] Each of the plurality of beams is assigned a beam deflection center above the construction plane, and the beam is aligned with the construction plane from the beam deflection center.

[0053] Each beam deflection center is assigned a projection center, which corresponds to the vertical projection of the beam deflection center's position onto the construction plane.

[0054] At least one segment of the cross-section of the object is solidified sub-region by sub-region, wherein the temporal order of scanning sub-regions (the solidification points of the sub-regions are assigned to the beam scan of these sub-regions) is defined such that sub-regions closer to the projection center of the beam are scanned before sub-regions farther away from the projection center.

[0055] In principle, the mentioned sub-regions can have any shape. Furthermore, sub-regions can have any shape in principle, and different sub-regions can also have different dimensions. Moreover, the building materials within the sub-regions do not necessarily have to be cured along a straight trajectory. Scanning along a cycloid trajectory (technically termed "wobbling") is also conceivable. However, if the trajectories in the sub-regions are chosen to be substantially parallel and have substantially equal lengths, then rectangular or square-shaped sub-regions are preferably chosen simultaneously. If two trajectories are parallel to each other at least 80%, preferably at least 95%, of the length of the shorter of the two trajectories, then there is a substantially parallel extension of these two trajectories. In the case of rectangular or square-shaped sub-regions, it is also particularly easy to cover cross-sectional sections of objects having sub-regions that are adjacent to each other without gaps.

[0056] Assuming the same method is used to determine the spatial distances from the projection center to all sub-regions, there are no restrictions on how the distances are determined. For example, the average distance from all points to be solidified within a sub-region to the projection center can be defined as the distance from that sub-region to the projection center. However, for example, the minimum distance from all points to be solidified within a sub-region to the projection center can also be defined as the distance from that sub-region to the projection center.

[0057] In the method according to the invention, it can result in additively manufactured objects with improved uniformity. This advantage also stems from the fact that the deposition of impurities with anisotropic or spatially non-uniform distribution is considered when the beam is incident obliquely onto the build plane. As described above, when the beam is incident obliquely, impurities preferentially deposit in the build plane toward the projection center. If sub-regions allocated the same beam for scanning are scanned in such a manner that those sub-regions with smaller distances to the projection center of the beam are scanned before those with larger distances to the projection center, this results in sub-regions being scanned one after another, starting from the one closest to the projection center and ending at the one furthest from the projection center. As a result, impurities generated during the scanning of sub-regions are always deposited (towards the projection center) on the already cured build material. This leads to improved uniformity of the cured object because impurities cannot impair the curing process of subsequent sub-regions, which would occur if the scanning order were reversed. In particular, uniformity is improved regardless of the corresponding orientation of the airflow through the build area.

[0058] Preferably, in a sub-region that defines the time sequence of scanning, the angle between the motion vector at each curing point and the connecting vector from that curing point to the projection center of the beam for that sub-region is less than a predetermined maximum angle γ1.

[0059] By combining the advantages of favorable selection of motion vector direction during scanning trajectory with the advantages of favorable selection of scanning sequence for sub-regions through the described process, a more uniform component can be obtained. For good results, a maximum angle γ1 of 90° is preferably selected. However, satisfactory results can still be obtained even at maximum angles between 90° and 135°. The smaller the maximum angle, the better the results. Therefore, depending on quality requirements, maximum angles such as 75°, 60°, and 45° can also be selected.

[0060] Preferably, in at least one sub-region (where the curing point is assigned to the beam scan of that sub-region), the scanning order of the trajectories is defined such that trajectories closer to the projection center of the beam are scanned before trajectories farther from the projection center.

[0061] Assuming that the same method is used to determine the spatial distances of all trajectories within a sub-region to the projection center, there are no restrictions on how the distances are determined. For example, the average distance from all points on a trajectory to the projection center can be defined as the distance from the trajectory to the projection center. However, it is also conceivable, for example, to define the minimum distance from each point on a trajectory to the projection center as the distance from the trajectory to the projection center.

[0062] By combining the advantages of advantageously selecting the scanning order of the trajectory within a sub-region, preferably within each sub-region, with the advantages of advantageously selecting the scanning order of the sub-region, a more uniform component can be obtained.

[0063] More preferably, the minimum distance from the solidified point in a sub-region to the projection center is used as a measure of the distance of the sub-region from the projection center.

[0064] The scanning order of sub-regions can be defined in a simple way by defining the distance from the described sub-region to the projection center.

[0065] More preferably, the segment has multiple sub-regions, each sub-region having a rectangular shape in a top view on the construction plane, with trajectories in the segment extending substantially parallel to each other and substantially parallel to the lateral side of the sub-region, wherein the length of a perpendicular line from the projection center to a straight line extending parallel to the longitudinal side of the sub-region serves as a measure of the distance between the sub-region and the projection center.

[0066] By defining the distance from the sub-region to the projection center in this way, the scanning order can be specified in a defined manner, especially for side-by-side rectangular sub-regions.

[0067] More preferably, during the curing of the cross-section of the object present in different layers, the longitudinal sides of the plurality of sub-regions in the different layers have an orientation that changes in the construction plane.

[0068] Changing the orientation of sub-regions in the construction plane layer by layer (from one layer to another) can lead to a reduction in the anisotropy of the properties of the manufactured object. The more frequently sub-regions are rotated layer by layer, the more isotropic properties can be achieved in a plane parallel to the construction plane. For example, if the orientation of the trajectory in a sub-region is chosen such that the trajectory always intersects the longitudinal side of the sub-region at a specified angle, then the different orientations of the sub-regions layer by layer (from one layer to another) also result in different orientations of the trajectories within them layer by layer (from one layer to another). This can lead to different determination of the scanning order of the sub-regions layer by layer, and in particular, to different configurations of the laser beam deflection center with respect to the sub-regions, in order to ensure optimized directions of motion vectors and scanning order relative to the corresponding projection centers. In particular, the layer rotation angle δ of the sub-region rotating from one layer to another can be determined in relation to a maximum angle γ1 and / or a minimum angle γ2 predetermined for the sub-region.

[0069] More preferably, in each of the sub-regions in which the scanning time sequence is defined, the motion vector at the solidification point has an angle greater than a predetermined minimum angle γ2 relative to the straight line connecting the solidification point to the projection center of the beam used.

[0070] If the trajectory's extension direction has a small angle relative to the connecting vector of the solidified point on the trajectory toward the projection center, then impurities will deposit approximately along the trajectory itself when the beam is incident obliquely on the construction plane. Thus, damage to adjacent trajectories is not significant. Therefore, it is useful to define a minimum angle γ2 and specify a particular order of scanning sub-regions only when this minimum angle is exceeded. Preferably, a value of 45° can be chosen for the minimum angle, even more preferably a value of 60°, and even more preferably a value of 75°.

[0071] When manufacturing a three-dimensional object using additive manufacturing equipment, an airflow can be passed through a corresponding solidification point during scanning. Preferably, in order to scan a solidification point in at least one segment of a cross-section of an object, a beam deflection center is selected such that, with respect to this beam deflection center, a directional component of the airflow points from the solidification point to a projection center assigned to that beam deflection center.

[0072] Specifically, when doing so, the angle between the airflow direction and the line connecting the solidification point and the projection center can be selected to be less than 90°, preferably less than 45°, and more preferably less than 30°. Ideally, the airflow should be precisely directed towards the projection center.

[0073] Therefore, by taking the direction of airflow into consideration, the effects achievable by the present invention can be further improved.

[0074] More preferably, the method is implemented for a section having at least one solidified point, wherein when scanning the at least one solidified point, the beam deflection angle exceeds the minimum deflection angle α1, wherein the beam deflection angle is defined as the arctangent of the quotient of the distance from the solidified point to the projection center and the length of the projection line of the beam deflection center, wherein the projection line of the beam deflection center is a perpendicular line to the construction plane, which connects the projection center and the beam deflection center.

[0075] The more obliquely the beam is incident on the building plane, the more pronounced the deposition of impurities in the preferred direction will be. Therefore, for small beam deflection angles, the process according to the invention can be omitted. To determine the minimum deflection angle α1, preliminary tests can be performed on the building material to be used and the beam parameters to be applied (e.g., laser power, beam diameter, etc.). In this case, the minimum deflection angle α1 will also depend on the acceptable degree of inhomogeneity of the cured building material in the object to be manufactured. Experience shows that for most metal-containing powders used as building materials, a minimum deflection angle α1 generally required for component uniformity can be specified, which is greater than or equal to 16°, preferably greater than or equal to 13°, more preferably greater than or equal to 10°, and particularly preferably greater than or equal to 7.5°.

[0076] More preferably, a beam is used to scan the building material along a trajectory, the beam deflection angle α of which does not exceed a predetermined maximum deflection angle α2, wherein the beam deflection angle is defined as the arctangent of the quotient of the distance from the solidification point to the projection center and the length of the projection line of the beam deflection center, wherein the projection line of the beam deflection center is a perpendicular line to the building plane, which connects the projection center and the beam deflection center.

[0077] The process described is useful when multiple beam deflection centers exist. This avoids enhanced unilateral deposition of impurities on the construction plane during scanning of the construction material. Preferably, the maximum deflection angle α2 is the same as the minimum deflection angle α1, which, when exceeded, should be performed according to the invention.

[0078] More preferably, for larger beam deflection angle α values, different energy input parameter values ​​are specified compared to for smaller beam deflection angle α values, wherein the beam deflection angle is defined as the arctangent of the quotient of the distance from the solidification point to the projection center and the length of the projection line of the beam deflection center, the projection line of the beam deflection center being a perpendicular line to the construction plane, the perpendicular line connecting the projection center and the beam deflection center.

[0079] The inventors have discovered that by modifying energy input parameters (such as laser power, deflection speed during beam scanning, etc.), it is possible to suppress the increased deposition of impurities on the construction plane as the beam deflection angle increases.

[0080] More preferably, the number of transitions from one beam to another during the scanning of the trajectory in the segment is limited to a maximum value M.

[0081] When scanning a segment using multiple beams from different beam deflection centers, the transition from one beam to another can be understood as scanning a first curing point with the first beam and a second curing point directly adjacent to the first curing point with the second beam. Specifically, if the scanning process performed with the first beam is interrupted and the scanning process continues with the second beam, ensuring the optimized direction of the motion vector during the scanning, this will lead to an increase in the scanning process time. This is why specifying a maximum value M for the number of changes ensures that the expected manufacturing time of the object to be manufactured does not exceed this limit.

[0082] More preferably, the maximum value M is determined in relation to the mass of the segment and / or the specified manufacturing time of the object.

[0083] Preferably, specifications for the quality or uniformity and / or manufacturing time of sections of an object are established by means of operator input at an input terminal, particularly a graphical user interface. This allows the operator to specify individually which sections of the cross-section of the object to be manufactured must have a high degree of uniformity and what specifications to make regarding the construction time (=manufacturing time).

[0084] Specifically, the operator can use operator input on an input terminal, particularly a graphical user interface, to select one of n predetermined, sequentially occurring quality or uniformity levels to specify the quality or uniformity. Here, n is a natural number greater than 1, and preferably, but not necessarily, equal to the number of beams or beam deflection centers available for the scanning segment. It is further assumed that the predetermined quality or uniformity levels follow a sequential relationship and are all distinct from each other. The specification of discrete uniformity levels is advantageous on the one hand for operability, and on the other hand for the adaptability of the method according to the invention to a given additive manufacturing apparatus. Instead of the manufacturing time of the object, the manufacturing time of the cross-section of the object can also be explicitly specified or selected from a range of possible manufacturing times. The specified or selected manufacturing time directly affects the manufacturing time of the object.

[0085] More preferably, the plurality of beams are distributed to the trajectory in such a way that the maximum time difference between the durations required for the laser beams to scan the allocated curing points within the segment is minimized.

[0086] Typically, the beams to be assigned to a trajectory or sub-region for scanning can be selected randomly or according to pre-established rules. Specifically, when the orientation of a sub-region in the construction plane changes from one layer to another with a predetermined layer rotation angle, this rule can depend on the value of the layer rotation angle. This rule can further depend on specified maximum angle γ1 and / or minimum angle γ2 (these angles can also be selected differently in different layers).

[0087] Preferably, the method according to the invention is implemented for a segment that is at least partially part of the bottom surface region of the cross-section of an object, the bottom surface region being defined such that at least one of the p layers below the bottom surface region does not specify the curing of the building material, where p is a predetermined natural number, and / or the segment is at least partially part of the top surface region of the cross-section of an object, the top surface region being defined such that at least one of the q layers above the top surface region does not specify the curing of the building material, where q is a predetermined natural number.

[0088] Achieving good surface quality is particularly important in the bottom and top surface areas, as these surfaces are visible from the outside. Through this further development, significant improvements in surface quality have been observed for p=1 and q=1; however, if uncured building material is located in layers following or even further down the chain, it may also affect curing properties. If values ​​for p and / or q are chosen to be less than 5, preferably less than 10, or even less than 25, an effect on external surface quality can be observed. Specific values ​​for parameters p and q can be determined based on experience with particular building materials and specific generative layer construction equipment (e.g., after initial testing), thereby determining when the influence of uncured building material still exists.

[0089] More preferably, the method is applied to a segment that is at least partially a component of the contour region of the object's cross-section.

[0090] The contour region is the edge region of an object's cross-section, forming part of the object's outer surface after it is manufactured, and therefore should have high quality. Typically, if possible, one attempts to achieve high quality by scanning the edges of the object's cross-section in a single pass. According to this further development of the invention, the difference from conventional methods lies in that the positions of the individual curing points relative to the projection center are considered as described above when scanning the surface region. Therefore, in particular, the direction and / or sequence of the motion vector relative to the projection center (the portion of the contour region to be cured is scanned relative to the projection center in this order) are considered. This ensures improved surface quality. Here, the segment can include not only a portion of the contour region but also the entire contour region.

[0091] In the additive manufacturing method for manufacturing three-dimensional objects according to the present invention, the object is manufactured by applying building materials layer by layer and by solidifying the building materials in a building plane using the additive manufacturing equipment. The solidification of the building materials is achieved by an energy input device by supplying radiant energy to solidification points in each layer that are assigned to the cross-section of the object in that layer. The radiant energy is supplied by scanning these solidification points along multiple trajectories in the building plane by a plurality of beams provided by the energy input device. The energy input device is controlled by a method for controlling an energy input device for additive manufacturing equipment according to the present invention.

[0092] Specifically, the energy input device may have several laser sources, from which laser beams are supplied to several scanners (especially galvanometer scanners) that serve as beam deflection centers.

[0093] In additive manufacturing, it is possible to pass (or guide) airflow through corresponding curing points during scanning. Advantageously, the manufacturing method is implemented such that, in at least one segment of the object's cross-section, a directional component of the airflow points from the curing point toward the projection center and / or is opposite in direction to the motion vectors of the plurality of beams.

[0094] Here, the movement of the beam can be oriented toward a predetermined direction of airflow, or, if possible in an additive manufacturing apparatus, the direction of airflow can be adapted to the movement of the beam.

[0095] Specifically, the angle between the airflow direction and the connecting line between the solidification point and the projection center can be less than 90°, preferably less than 45°, and more preferably less than 30°. Ideally, the airflow should be precisely directed towards the projection center.

[0096] Furthermore, the angle between each motion vector and the airflow direction can be greater than 90°, preferably greater than 135°, and more preferably greater than 150°. Ideally, the airflow direction is exactly opposite to the direction of the motion vector.

[0097] Therefore, by choosing the favorable airflow direction, the effects achievable by the present invention can be further improved.

[0098] According to the invention, an energy input device for controlling an additive manufacturing apparatus to manufacture a three-dimensional object using the additive manufacturing apparatus is provided, wherein the object is manufactured by applying building material layer by layer and by solidifying the building material in a building plane. The solidification of the building material is achieved by the energy input device supplying radiant energy to solidification points in each layer, which are assigned to cross-sections of the object within that layer. The radiant energy is supplied by scanning these solidification points along multiple trajectories in the building plane using a plurality of beams provided by the energy input device.

[0099] Each of the plurality of beams is assigned a beam deflection center above the construction plane, and the beam is aligned with the construction plane from the beam deflection center.

[0100] The device for controlling the energy input of the additive manufacturing equipment includes a distribution device that assigns a projection center to each beam deflection center, the projection center corresponding to the vertical projection of the beam deflection center's position onto the build plane.

[0101] The device for controlling the energy input device includes a scanning control unit configured such that the scanning control unit defines a trajectory and the direction of motion vectors of the plurality of beams as they scan the trajectory in at least a segment of the cross-section of the object, such that at each solidification point in the segment, the motion vector has an angle relative to the connecting vector from the solidification point to the projection center of the beam used that is less than a predetermined maximum angle γ1.

[0102] The device for controlling the energy input device can implement the aforementioned method for controlling the energy input device, wherein the direction of the motion vector along the trajectory is defined. Here, the various components of the device, namely, in particular the distribution device and the scanning control unit, can be implemented individually by software, individually by hardware, or by a combination of hardware and software.

[0103] According to the invention, an energy input device for controlling an additive manufacturing equipment to manufacture a three-dimensional object using the additive manufacturing equipment manufactures the object by applying building material layer by layer and by solidifying the building material in a building plane. The solidification of the building material is achieved by the energy input device supplying radiant energy to solidification points in each layer, which are assigned to cross-sections of the object within that layer. The radiant energy is supplied by scanning these solidification points along multiple trajectories in the building plane using several beams provided by the energy input device.

[0104] Each of the plurality of beams is assigned a beam deflection center above the construction plane, and the beam is aligned with the construction plane from the beam deflection center.

[0105] The device for controlling the energy input includes a distribution unit that assigns a projection center to each beam deflection center, the projection center corresponding to the vertical projection of the beam deflection center's position onto the construction plane.

[0106] The device for controlling the energy input device includes a scanning control unit configured such that the scanning control unit specifies the curing of at least one segment of a cross-section of an object in sub-regions, wherein the tracks in each sub-region are substantially parallel to each other, and in at least one sub-region (whose curing point is scanned using a beam assigned to that sub-region), the scanning order of the tracks is defined such that the tracks closer to the projection center of the beam are scanned before the tracks further away from the projection center.

[0107] This device for controlling the energy input device enables the aforementioned method for controlling the energy input device, wherein the order of the trajectories within the scanning sub-region is defined or specified. Here, the various components of the device, particularly the distribution device and the scanning control unit, can be implemented individually through software, individually through hardware, or through a combination of hardware and software.

[0108] According to the invention, an energy input device for controlling an additive manufacturing apparatus to manufacture a three-dimensional object using the additive manufacturing apparatus is another device, wherein the object is manufactured using the additive manufacturing apparatus by applying building material layer by layer and by building material solidifying in a building plane. The solidification of the building material is achieved by the energy input device supplying radiant energy to solidification points in each layer, which are assigned to the cross-section of the object in that layer. The radiant energy is supplied by scanning these solidification points along multiple trajectories in the building plane using a plurality of beams provided by the energy input device.

[0109] Each of the plurality of beams is assigned a beam deflection center above the construction plane, and the beam is aligned with the construction plane from the beam deflection center.

[0110] The device for controlling the energy input includes a distribution unit that assigns a projection center to each beam deflection center, the projection center corresponding to the vertical projection of the beam deflection center's position onto the construction plane.

[0111] The device for controlling the energy input device includes a scanning control unit configured to specify the curing of at least one segment of the cross-section of an object in a sub-regional manner, wherein the temporal order of scanning the sub-regions is defined such that sub-regions closer to the projection center of the beam are scanned before sub-regions farther away from the projection center, and the curing points of the sub-regions are scanned using the beams assigned to these sub-regions.

[0112] The device for controlling the energy input device can implement the aforementioned method for controlling the energy input device, in which the scanning sequence of sub-regions is specified or defined. Here, the various components of the device, namely, in particular the distribution device and the scanning control unit, can be implemented individually by software, individually by hardware, or by a combination of hardware and software.

[0113] According to an additive manufacturing apparatus for manufacturing three-dimensional objects, the object is manufactured by applying building materials layer by layer and by solidifying the building materials in a building plane. The solidification of the building materials is achieved by an energy input device supplying radiant energy to solidification points in each layer, which are assigned to cross-sections of the object within that layer. The radiant energy is supplied by scanning these solidification points along multiple trajectories in the building plane using a plurality of beams provided by the energy input device. The additive manufacturing apparatus includes:

[0114] A layer application device suitable for applying a building material layer onto an existing, preferably selectively cured, building material layer, and

[0115] An energy input device is adapted to supply radiant energy to solidified points in each layer that are allocated to the cross-section of the object in that layer, wherein the radiant energy is supplied by scanning the solidified points along multiple trajectories in the construction plane using several beams provided by the energy input device.

[0116] The additive manufacturing equipment includes, according to the invention, a device for controlling an energy input device for the additive manufacturing equipment, and / or a device connected in terms of signal technology to, according to the invention, a device for controlling an energy input device for the additive manufacturing equipment.

[0117] Specifically, the device for controlling the energy input device present in the additive manufacturing equipment can also be integrated into a control device present in the additive manufacturing equipment and controlling the additive manufacturing process. Specifically, the device for controlling the energy input device present in the additive manufacturing equipment can also be a computer program, which controls the CPU present in the control device. Here, the connection in terms of signal technology means using physical lines or radio connections capable of transmitting control signals.

[0118] The object according to the invention can be made using the additive manufacturing method according to the invention. Attached Figure Description

[0119] Other features and advantages of the invention will become apparent from the description of exemplary embodiments with reference to the accompanying drawings.

[0120] Figure 1A partially cutaway schematic diagram of an exemplary apparatus for additive manufacturing of three-dimensional objects according to the present invention is shown.

[0121] Figure 2 An example of a process (“drawing shading lines”) for curing strip sub-regions of an object cross-section according to the present invention is illustrated schematically.

[0122] Figure 3 The positions of the beam deflection center and the projection center of the beam deflection center relative to the solidification point are shown in the construction plane.

[0123] Figure 4 An example of a process according to the first embodiment is shown.

[0124] Figure 5 The results of a study illustrating the influence of the beam's motion direction on the quality of a component during the scanning of building materials are shown schematically.

[0125] Figure 6 An example of a process according to the second embodiment is shown.

[0126] Figure 7a and Figure 7b The findings of the investigation regarding the order of scan trajectories within the sub-region are illustrated schematically.

[0127] Figure 8 An example of a process according to a third embodiment is shown.

[0128] Figure 9a and Figure 9b The images schematically illustrate the incident laser beam on the top layer of the building material at different beam tilt angles during the scanning process.

[0129] Figure 10 The process taking into account the magnitude of the beam deflection angle is shown.

[0130] Figure 11 An example of a variation of the process according to the second embodiment is shown.

[0131] Figure 12a and Figure 12b The process of melting building materials in different trajectory processing directions is illustrated schematically.

[0132] Figure 13 A schematic structure of a device for controlling an energy input device according to the present invention is shown. Detailed Implementation

[0133] To describe the present invention, examples of laser sintering or laser melting equipment will be used first below. Figure 1 The additive manufacturing apparatus according to the present invention is described below.

[0134] To construct object 2, the laser sintering or laser melting equipment 1 includes a processing chamber or construction chamber 3 with chamber walls 4. A construction container 5, open upwards and with container walls 6, is arranged within the processing chamber 3. A working plane 7 (also called a construction plane) is defined by an upper opening in the construction container 5, and the area within this opening of the working plane 7 that can be used to construct object 2 is called the construction area 8.

[0135] A support member 10, movable in a vertical direction V, is provided in the container 5. A base plate 11 is attached to this support member, which closes the container 5 at the bottom, thus forming the bottom of the container. The base plate 11 can be a plate formed separately from the support member 10 and attached to the support member 10, or the base plate can be integrally formed with the support member 10. Depending on the powder and process used, a construction platform 12 can also be mounted on the base plate 11 as a construction base for constructing the object 2 thereon. However, the object 2 can also be constructed on the base plate 11 itself, and then the base plate serves as the construction base. Figure 1 In the middle, below the working plane 7, the object 2 to be formed on the construction platform 12 in the container 5 is shown in an intermediate state. The object has multiple solidified layers, which are surrounded by uncured construction material 13.

[0136] The laser sintering or laser melting apparatus 1 further includes: a storage container 14 for building material 15, which in this example is a powder that can be cured by electromagnetic radiation; and a coater 16 movable in the horizontal direction H for coating the building material 15 within the building zone 8. Optionally, a heating device, such as a radiation heater 17, may be disposed in the processing chamber 3 for heating the coated building material. For example, an infrared radiator may be provided as the radiation heater 17.

[0137] The exemplary additive manufacturing apparatus 1 also includes an energy input device 20 with a laser 21 that generates a laser beam 22, which is deflected by a beam deflection center 23 (e.g., one or more galvanometer mirrors along with associated drivers) and focused by a focusing device 24 via a coupling window 25 disposed in the chamber wall 4 on the upper side of the processing chamber 3. In particular, multiple lasers and / or beam deflection centers can also be provided. This allows the manufacturing process to be performed in a shorter time, as the building material can then be scanned and cured simultaneously at multiple different points using multiple beams.

[0138] therefore, Figure 1The specific structure of the laser sintering or laser melting equipment shown is merely an example of the invention and can, of course, be modified, especially when using an energy input device different from that shown. To indicate that the area of ​​the radiation incident region on the building material does not need to be very small (“point-like”), the term “beam” is often used synonymously with “ray” in this application.

[0139] The laser sintering equipment 1 also includes a control unit 29, which coordinates the various components of the equipment 1 to carry out the construction process. Alternatively, the control unit may be located partially or completely outside the additive manufacturing equipment. The control unit may include a CPU whose operation is controlled by a computer program (software). The computer program may be stored separately from the additive manufacturing equipment in a storage device, from which it can be loaded (e.g., via a network) into the additive manufacturing equipment, and particularly into the control unit.

[0140] During operation, the support member 10 is lowered layer by layer via the control device 29, the coating device 16 is controlled to coat new powder layers, and the energy input device 20, i.e., in particular the beam deflection center 23 and optionally the laser 21 and / or focusing device 24, is controlled to solidify the corresponding layer at the location corresponding to the corresponding object by scanning these locations with a laser. Here, in this application, the unit 39 within the control device 29 responsible for controlling the energy input device 20 is referred to as the device 39 for controlling the energy input device. However, it should be emphasized that the device for controlling the energy input device can also exist outside the control device 29 in the same manner (also as a computer program), as long as it is ensured that the device 39 for controlling the energy input device for additive manufacturing of the object can interact sufficiently with the control device 29, i.e., in particular, can exchange signals.

[0141] Even though this invention primarily relates to laser sintering or laser melting methods or equipment, it can also be applied to electron beam melting.

[0142] When the energy input device is controlled, the curing of the building material layers is determined by a time sequence corresponding to the movement of the beam along its trajectory through the building material. Here, Figure 13 A schematic structure of the aforementioned device 39 for controlling the energy input device is shown, wherein the scanning control unit 39b specifies the time sequence, wherein... Figure 2 An example of this process is given. Figure 2In this example, the cross-section 50 of the object to be cured, having a rectangular shape, is subdivided into an inner region or core region 52 and a contour region 51. Typically, the contour region 51 is assigned different parameters for the energy input to the building material compared to the inner region 52. For example, the contour region 51 is scanned using a laser beam (as an example of a beam) whose trajectory extends along the contour. In this example, the inner region 52 is cured in such a way that it is subdivided into multiple sub-regions 53, typically having an approximately rectangular or square shape and therefore also referred to as "strips" or "squares," and the scanning of the building material is then specified sub-region by sub-region. Figure 2 In the example, the laser beam moves along a parallel trajectory (hatching) 54 through the building material in each sub-region 53, thus creating a hatching-like moving pattern as the laser beam scans each sub-region 53. This process is also known in technical terms as "hatching". In this case, in Figure 2 In the image, the direction of the laser beam's movement along its trajectory is indicated by the arrow.

[0143] According to the present invention, the horizontal position of the beam deflection center is taken into account when controlling the energy input device. A distribution device 39a is provided for this purpose in the device 39 for controlling the energy input device. Reference is made below. Figure 3 To explain this process, a beam deflection center 23 is schematically shown above the construction area 8. A projection center 23' in the construction plane 7 is assigned to the beam deflection center 23 by the vertical projection of the beam deflection center 23 onto the construction area 8 (or construction plane 7). In this respect, as shown in the figure, the projection line 23k is a perpendicular line to the construction plane 7, connecting the projection center 23' with the beam deflection center 23.

[0144] By defining the projection center 23', the scanning process can be defined according to the positions of the points 64a, 64b, 64c to be fixed within the construction area relative to the projection center 23', as will be explained below with reference to several examples.

[0145] First exemplary embodiment

[0146] According to a first exemplary embodiment, the device for controlling the energy input device selects the direction of the motion vector of the beam used to scan the location to be cured or the cured point in the construction area 8 based on the position of the curing point relative to the projection center 23'. (Refer to below) Figure 4 Explain the process.

[0147] Figure 4A top view of the construction area 8 is shown, in which the position of the projection center 23' of the beam deflection center 23 and the positions of four exemplary curing points 74a, 74b, 74c, and 74d can be seen. Furthermore, the figure shows the corresponding motion vectors 75a, 75b, 75c, and 75d as the beam originating from the beam deflection center 23 moves through the curing points 74a, 74b, 74c, and 74d.

[0148] It can be seen that the direction of the motion vector at positions 74a, 74b, and 74d is defined by the device used to control the energy input device, such that the motion vector has a component s pointing towards the projection center 23'. To better illustrate the direction, in Figure 4 For each solidification point 74a, 74b, 74c and 74d, a straight connecting line 73a, 73b, 73c and 73d to the projection center 23' is drawn with dashed lines.

[0149] exist Figure 4 It can also be seen that at the solidification point 74c, the motion vector is limited to having only a component q perpendicular to the connecting line 73c. ​​In this case, the motion vector 75c along the trajectory forms an angle γ of 90° with the connecting line 73c.

[0150] The background to the described process is that the inventors discovered that when the motion vector has a large component pointing away from the projection center, the object's properties deteriorate. Therefore, Figure 5 The results of the study are schematically illustrated, in which a layer of metal powder is applied in a conventional laser sintering apparatus and then scanned with a laser beam. For the study, the construction zone 8 was divided into sixteen square segments A to P, as shown. Figure 5 As shown in the upper part, the position of the projection center 23' of the beam deflection center 23 used for scanning is also marked. Here, according to reference... Figure 2 The described process involves scanning. Thus, the various sub-regions 53 in the cross-section are scanned in such a way that, in each sub-region 53, the laser beam moves along a parallel trajectory (shadow line) 54 through the building material.

[0151] The lower part of the figure shows a top view of segment A after the scan. Within segment A, sixteen sub-regions 53 can be seen, along with... Figure 2Conversely, they are not directly adjacent to each other. Within each sub-region, the arrows indicate the direction of travel along the trajectory. Note that within each sub-region 53, the parallel trajectories 54 travel in the same direction; that is, the motion vectors point in the same direction during the scanning of a sub-region. Furthermore, the position depicted by the arrows within each sub-region 53 indicates the position of the trajectory 54 first scanned within that sub-region. Finally, it should be noted that, for clarity, only two of the sixteen sub-regions in the figure are labeled 53 and 54.

[0152] Figure 5 The lower part shows scanned sub-regions 53 with three different shading densities and a sub-region 53 without shading. The different shading densities are intended to represent different properties of the cured building material. Here, densely arranged shading indicates a larger local fluctuation in the volume of cured material in sub-region 53 compared to less densely arranged shading or even absent shading in sub-region 53. Thus, absent shading indicates the maximum achievable uniformity or maximum achievable volume percentage of the cured material in sub-region 53. In particular, it can be seen that different directions of the motion vector relative to the projection center 23' result in different shading densities. The magnitude of the component of the motion vector pointing towards or away from the projection center also plays a role. The stronger the motion vector is oriented towards or away from the projection center, the more pronounced the effect to be observed.

[0153] It should also be noted that the above studies are conducted on different directions of airflow across the construction area, and corresponding results are always obtained. Figure 5 The result.

[0154] The above research clearly demonstrates that when using beam scanning to construct materials, the directional component of the motion vector pointing away from the projection center should be avoided from being too large. Preferably, the directional component of the motion vector pointing away from the projection center should be completely avoided. However, in practice, it may prove necessary to deviate from the preferred approach due to other boundary conditions, such as not exceeding the predetermined manufacturing time for the object. Therefore, in practice, it is advantageous to use the aforementioned approach at least when the trajectory to be scanned is below the maximum angle γ1 relative to the line connecting to the projection center.

[0155] The inventors explain the observed behavior by examining the characteristics of a keyhole welding process (deep penetration welding) used for melting metal powder. In the keyhole welding process, high temperatures are generated in the material, causing evaporation, and particularly radiation penetrates into vapor capillaries at the material surface. Multiple reflections at the edges of the vapor capillaries allow more energy to be specifically introduced into the material. These temporarily formed vapor capillaries are commonly referred to as "keyholes." As explained below with reference to Figure 9, the observed characteristics can be explained by the fact that, when a laser beam is incident obliquely on the building material, the keyholes form differently depending on the direction of motion.

[0156] Figures 9A and 9B, based on the interpretive model, schematically illustrate the incident laser beam on the metal powder used. In each case, the beam is in the horizontal direction (in... Figure 9a and Figure 9b The arrow moves upwards (from left to right), which is indicated in each case by an arrow pointing to the right. Furthermore, in... Figure 9a and Figure 9b In Figure 9A, reference numeral 22 indicates a beam that points from a beam deflection center (not shown) toward the building material. In Figure 9A, when scanning the building material, the beam moves away from the projection center of the beam deflection center (also not shown), while in Figure 9B, when scanning the building material, the beam moves toward the projection center.

[0157] Figures 9A and 9B both schematically illustrate the aperture formed by the provided radiant energy. This aperture has approximately its maximum size in the direction of beam incidence, and therefore is inclined relative to the vertical direction when the beam is incident obliquely on the building material. (As shown in...) Figure 9a As can be clearly seen, this erosion and replacement of the uncured powder material, while Figure 9b This is not how it happened. As a result, Figure 9a The cured layer in the medium exhibits poor properties, particularly with partially reduced or drastically varied layer thickness. Figure 9a Not shown in the schematic diagram.

[0158] Although Figure 9 exemplarily shows a case where the beam's motion vector has only a directional component toward or away from the projection center, in reality, there will usually also be a directional component perpendicular to the line connecting the fixed point and the projection center. Therefore, if the directional component perpendicular to the line is sufficiently large, satisfactory results can also be obtained if the directional component away from the projection center is not too large; in other words, if the angle between the motion vector and the line connecting to the projection center is less than the maximum angle.

[0159] As can be seen from the given description, the most significant improvement in uniformity is achieved when the beam is incident obliquely onto the construction plane, as per the present invention. This refers to... Figure 10 An explanation was provided.

[0160] Figure 10 The view and Figure 3 The views are very similar. Specifically, the position of the beam deflection center 23 above its associated projection center 23' in the construction plane is shown, along with schematic diagrams illustrating the beam directions 163a, 163b, and 163c when the beam is aligned with the solidification points 164a, 164b, and 164c, respectively. The figure also shows the corresponding beam deflection angles α6, α1, and α4 between the respective directions 163a, 163b, and 163c and the projection line 23k of the beam deflection center 23. Here, the solidification point 164c is shown only for the purpose of illustrating the minimum deflection angle α1.

[0161] When in Figure 10 The example specifies how the energy input device in the additive manufacturing equipment should be controlled for scanning curing points 164a and 164b, and then the corresponding beam deflection angle α6 or α4 is first compared with the minimum deflection angle α1. Since the beam deflection angle α4 for curing point 164b is greater than the minimum deflection angle α1, the direction of the motion vector at curing point 164b is set such that the predetermined maximum angle between the motion vector and the line connecting to the projection center is not reached. The beam deflection angle α6 for curing point 164a is less than the minimum deflection angle α1. Therefore, at curing point 164a, a direction of the motion vector is allowed in which the predetermined maximum angle between the motion vector and the line connecting to the projection center is exceeded.

[0162] Although the advantages of the method according to the first exemplary embodiment mentioned above are independent of the orientation of the airflow, such as through the construction area, i.e. the location to be cured, as described in WO2014 / 125280A2, this does not mean that the results cannot be further improved by taking the orientation of the airflow into consideration.

[0163] As indicated above in conjunction with Figure 9, it is unfavorable if the building material is displaced when laser radiation is incident on it, i.e., it deposits on the still-uncured building material at the point where it will still be cured. Therefore, as the airflow passes through the point to be cured during scanning, the motion vectors of the plurality of beams 22 in the scanning trajectory 54 should be defined such that the directional component of the airflow is opposite to the direction of the motion vector. In this way, the airflow suppresses deposition on the material to be cured. Alternatively, the direction or orientation of the airflow can be adjusted if the additive manufacturing equipment allows.

[0164] Second exemplary embodiment

[0165] The second exemplary embodiment relates to the above reference. Figure 2 The description outlines the typical process of scanning the position of a cross-section sub-region by sub-region. According to a second exemplary embodiment, the order of scanning the trajectory (shadow line) within each sub-region is determined by a device for controlling the energy input device based on the position of the trajectory relative to the projection center. (Refer to the following...) Figure 6 Explain the process.

[0166] Figure 6 and Figure 2 Very similar. (And) Figure 2 In contrast, the position of the projection center 23' relative to sub-region 53 is shown. Furthermore, within each sub-region 53, the temporal order in which the trajectory 54 is scanned is indicated in each case by an arrow depicting the trajectory processing direction 86. It can be seen that, in Figure 6 In each sub-region 53, the rightmost trajectory is scanned first, then all other trajectories 54 are scanned sequentially until the leftmost trajectory in that sub-region is scanned. Figure 6 In the example, the device used to control the energy input device therefore specifies the order in which the trajectories are scanned, such that the trajectory with a larger distance from the projection center is scanned before the trajectory with a smaller distance from the projection center.

[0167] An exemplary way to determine the distance from the trajectory to the projection center 23' within sub-region 53 is to construct a connection vector 83 from the corresponding starting point of the trajectory to the reference point of the projection center 23' for each of the trajectories 54 in sub-region 53, and determine the length of the component 83s of the connection vector perpendicular to the trajectory. Then, for trajectories that are substantially parallel to each other within a sub-region, a trajectory processing direction 86 perpendicular to the trajectory can be specified based on the length of the component 83s. As a result, trajectories closer to the projection center 23' are scanned before those farther away from the projection center 23'. Of course, another reference point on the trajectory can be chosen instead of the starting point to construct the connection vector. However, it is advantageous to refer to the starting or ending point as the reference point when not all trajectories within a sub-region are precisely parallel to each other and / or have precisely the same length.

[0168] The inventors were able to determine that, compared to scanning the trajectory without considering the chosen strategy, the described process can achieve more uniform curing of the building material (e.g., identified by lower surface roughness in the scanned area). Here, improvements can be achieved regardless of the airflow direction present in each case. Figure 7 schematically illustrates exemplary results of the inventors' research on the sequence of scanning trajectories within a sub-region.

[0169] like Figure 5The study shows that a layer of metal powder is applied in a conventional laser sintering apparatus and then scanned with a laser beam. Figure 7a and Figure 7b The top view of the square section of construction area 8 after it has been scanned, and the position of the projection center 23', are shown respectively. Figure 5 As shown in the lower part, sixteen sub-regions 53 are visible, and... Figure 2 Instead, they are not directly adjacent to each other. In each sub-region, arrow 88 indicates the direction of the laser beam's trajectory during scanning, where in all sub-regions 53, parallel trajectories are scanned in the same direction, i.e., the motion vectors point in the same direction during scanning. For clarity, in Figure 7a and 7b In each case, only one of the sixteen sub-regions is provided with a reference marker.

[0170] Figure 7a and Figure 7b The difference lies in the position of the arrows indicating the scanning direction in each sub-region. Figure 7a In the middle, the arrows 88 are respectively placed at the upper left edge of sub-region 53, while... Figure 7b In the image, the arrows are positioned at the bottom right edge of each sub-region. The reason for the different arrangements is that... Figure 7a and Figure 7b In the image, the position of arrow 88 also indicates the trajectory scanned first within the sub-region. Therefore, in Figure 7a In the middle, the trajectory in each sub-region 53 is scanned from the top left to the bottom right, while... Figure 7b In the middle, the trajectory in each sub-region 53 is scanned from the bottom right to the top left.

[0171] and Figure 5 Similarly, Figure 7 shows scanned sub-regions 53 with three different shaded line densities and a sub-region 53 without shaded lines. The different shaded line densities are intended to represent different qualities achieved in different sub-regions. The denser arrangement of shaded lines in sub-region 53, compared to sub-region 53 with less densely arranged or even absent shaded lines, is intended to indicate greater surface roughness. Therefore, the absence of shaded lines indicates a surface with very low roughness. Specifically, by comparison... Figure 7a and Figure 7b It can be seen that higher quality (identifiable by lower surface roughness) can be achieved if the direction of the sequential scanning trajectory (trajectory processing direction) within the sub-region has a component pointing away from the projection center 23'. This result can be observed during scanning regardless of the direction of the gas flow across the construction area.

[0172] Furthermore, it can be seen that improvements are also achieved for those sub-regions 53 where the beam motion vector during trajectory scanning has a directional component pointing away from the projection center. This indicates that the method according to the second embodiment itself, regardless of the choice of the direction of the motion vector during scanning each trajectory, leads to improved quality of the solidified region. Therefore, in Figure 6 The process shown can also achieve improved uniformity, although the scanning direction (shadow direction) alternates in sub-region 53, i.e., every other trajectory has a directional component pointing away from the projection center 23'. If a particularly high uniformity of the manufactured component is desired, the processes / methods according to the first exemplary embodiment and the second exemplary embodiment should be combined with each other, which is readily achievable.

[0173] A possible explanation for the observed characteristics is given with reference to Figure 12. Similar to Figure 9, Figure 12 shows the location of the pinholes formed when the beam is incident on the powdered building material. However, unlike Figure 9, the beam moves perpendicular to the line connecting the corresponding solidification point to the projection center. Therefore, in Figure 12a and 12b In the left half, in each case, a section showing the orifice and two adjacent curing paths 54' perpendicular to the direction of beam motion is shown, i.e., the direction of beam motion is perpendicular to the plane of the drawing. Figure 12a and Figure 12b The difference between them is that, in Figure 12a The small and medium pores are tilted towards the uncured powder material, while... Figure 12b The small and medium-sized holes are inclined towards the two curing paths 54' of the already cured building material. Figure 12a and 12b The right half of the image shows top views of the layers currently being cured. From this top view, it can be seen that... Figure 12a The trajectory processing direction points towards the projection center 23' (not shown), while... Figure 12b The trajectory processing direction points away from the projection center by 23'.

[0174] In Figure 12 (as in Figure 9), the displacement of material through the orifice is indicated by two arrows on either side of the corresponding orifice. It can be seen that... Figure 12a In the process, material from the pores is deposited on the uncured powdery building material, while... Figure 12b In the middle, material from the pores is deposited on the curing path 54'. Therefore, in Figure 12a In such cases, the melting process is weakened when scanning subsequent adjacent trajectories, which leads to quality degradation, such as a rougher surface on the associated solidification path.

[0175] Similar to the first embodiment, in practice it can be proven that deviations from the process according to the second embodiment are necessary due to other boundary conditions, such as a predetermined manufacturing time for manufacturing the object that must not be exceeded. In this case, the process according to the second exemplary embodiment can be performed only in those sub-regions where the motion vector relative to the connecting line to the projection center has an angle exceeding the minimum angle γ2 when scanning the trajectory within the sub-region. This refers to... Figure 11 An explanation was provided.

[0176] Figure 11 A schematic top view of construction area 8 is shown, illustrating the position of projection center 23' relative to trajectories 154, 155, and 157 in different sub-regions. The connecting vector 181 to projection center 23' forms an angle γ2 with the motion vector along the exemplary trajectory 154, which is... Figure 11 In the example, it is defined as the minimum angle.

[0177] Using this definition of the minimum angle γ2, the trajectory processing direction 186 is defined for trajectory 155 in such a way that the trajectory located closer to the projection center 23' is scanned before the trajectory located farther from the projection center 23'. This is because, when scanning parallel trajectory 155, the angle γ5 between the direction of the motion vector and the corresponding connecting vector 183 to the projection center 23' is greater than the minimum angle γ2. The motion vector along parallel trajectory 157 forms an angle γ7 with the corresponding connecting vector 188, which is less than the minimum angle γ2. Therefore, for trajectory 157, a trajectory processing direction 187 is allowed, in which the trajectory closer to the projection center 23' is scanned after the trajectory farther from the projection center 23' when the processing direction is defined.

[0178] Similarly, in the second exemplary embodiment, the most significant improvement in uniformity is obtained when the beam is incident at an angle onto the construction plane, as performed according to the invention. In other words, for sufficiently perpendicular incident beams, the process described in the second exemplary embodiment can be omitted if the accuracy requirement is not very high. Therefore, referring to... Figure 10 The process / method shown in relation to the beam deflection angle can be applied in the same manner as the second exemplary embodiment.

[0179] Similar to the first embodiment, the results can be further improved if the direction of airflow is also taken into account.

[0180] As described above Figure 12aAs already mentioned, it is disadvantageous if, when laser radiation is incident on the building material, the material is displaced by the aperture in such a way that it deposits on the uncured building material at a location where it has not yet cured. Therefore, if the airflow passes through the area to be cured during scanning, not only should the trajectory processing direction be selected to point away from the projection center 23', but also, for fixation, such a beam deflection center 23 should be selected whose associated projection center 23' position results in one directional component of the airflow pointing from the curing point towards the projection center 23 during scanning. In this way, the airflow suppresses deposition on the still-curing material. Alternatively, if the additive manufacturing equipment allows for this, the direction or orientation of the airflow can also be adjusted.

[0181] Third Exemplary Example

[0182] Similar to the second exemplary embodiment, the third exemplary embodiment relates to the above references Figure 2 The general process of scanning the position of the cross-section sub-region by sub-region, as described in the third exemplary embodiment, is that the order in which the sub-regions are scanned is determined by a device for controlling the energy input device based on the position of the sub-regions relative to the projection center. (Refer to below) Figure 8 Explain the process.

[0183] Figure 8 and Figure 6 Very similar, but the trajectory processing direction 86 in the sub-region is not specifically indicated by the arrow. Figure 8 In the figure, the two sub-regions labeled 53a and 53b are distinguished from each other by an additional lowercase letter. This is to indicate that sub-region 53a was scanned before sub-region 53b because it is closer to the projection center 23'.

[0184] An exemplary way to consider the distance between a sub-region and the projection center is to determine the minimum distance from each sub-region to the projection center and scan the sub-regions as the size of the minimum distance increases; that is, first scan the sub-regions with the smallest minimum distance and last scan the sub-regions with the largest minimum distance. Figure 8 In the diagram, the minimum distance between sub-region 53a and projection center 23' is represented by the connecting vector or the straight connecting line 93.

[0185] Of course, the distance between the sub-region and the projection center can also be determined in other ways. For example, instead of defining the length of the shortest connecting line between the sub-region and the projection center as the distance, as just described, the component of the shortest connecting line perpendicular to the trajectory within the sub-region can be determined. The corresponding distance is... Figure 8 It is indicated by the figure mark 93p in the figure.

[0186] Similarly, regarding the process according to the third exemplary embodiment, the inventors were able to determine that more uniform curing of the building material could be achieved compared to not adhering to the preferred time sequence for sequentially scanning sub-regions as just described. Likewise, improvements can be achieved regardless of the airflow direction present in each case.

[0187] In the case of the second embodiment, especially in the presence of other boundary conditions, such as not exceeding a predetermined manufacturing time for manufacturing the object, the process according to the third embodiment can be limited to a sub-region in which the trajectory to be scanned has an angle relative to the connecting line to the projection center, said angle exceeding a minimum angle γ2. (The above is combined with...) Figure 11 The explanation can be similarly applied to the third exemplary embodiment.

[0188] Similarly, in the third exemplary embodiment, the most significant improvement in uniformity is obtained when the beam is incident at an angle onto the construction plane, as performed according to the invention. In other words, for sufficiently perpendicular incident beams, the process described in the third exemplary embodiment can be omitted if the accuracy requirement is not very high. Therefore, referring to... Figure 10 The process shown in relation to the beam deflection angle can be applied in the same manner as the third exemplary embodiment.

[0189] Similar to the second embodiment, the results can be further improved if the direction of airflow is also taken into account.

[0190] According to the third exemplary embodiment, by scanning a sub-region located closer to the projection center 23' of the beam 22 before scanning a sub-region located further away from the projection center 23', the uniformity of the properties of the manufactured object is improved. In this case, material deposition on uncured building material should also be avoided during scanning. Therefore, if the airflow passes through the location to be cured during scanning, the beam deflection center 23 should be selected for curing, the position of its associated projection center 23' causing one directional component of the airflow to point from the curing point in the sub-region towards the projection center 23 during scanning. In this way, the airflow suppresses deposition on the material still to be cured. Alternatively, if the additive manufacturing equipment allows this, the direction or orientation of the airflow can also be adjusted.

[0191] The processes described in the first, second, and third exemplary embodiments, including their modifications, can be arbitrarily combined with each other. Maximizing the uniformity of the properties of the additively manufactured object is achieved by simultaneously implementing the teachings of all three exemplary embodiments while controlling the energy input device. Finally, it should be noted that the aforementioned maximum angle γ1 and minimum angle γ2 need not be chosen symmetrically with respect to the connecting vector from the solidification point to the projection center. Instead, different values ​​can be assigned to the maximum angle γ1 and / or the minimum angle γ2 for motion vectors located on different sides of the connecting vector.

Claims

1. A method for controlling an energy input device (20) of an additive manufacturing equipment to manufacture a three-dimensional object using the additive manufacturing equipment, in, The object is manufactured using the additive manufacturing equipment by applying building materials layer by layer and by solidifying the building materials in the building plane (7). The solidification of the building materials is achieved by an energy input device by supplying radiant energy to solidification points in each layer that are assigned to the cross-section of the object in that layer. The radiant energy is supplied by scanning these solidification points along multiple trajectories (54) in the building plane (7) using several beams (22) provided by the energy input device (20). Each of the plurality of beams is assigned a beam deflection center (23) above the construction plane (7), and the beam is aligned with the construction plane from the beam deflection center. Each beam deflection center (23) is assigned a projection center (23') that corresponds to the vertical projection of the position of the beam deflection center (23) onto the construction plane (7). Solidify at least one segment of the object's cross-section, sub-region by sub-region. In at least one of the sub-regions (53), the solidified points of that sub-region are scanned using a beam (22) assigned to that sub-region, defining the scanning order of the trajectory (54) such that the trajectory closer to the projection center (23') of the beam is scanned before the trajectory farther from the projection center (23'), and The temporal order of the scanning 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 away from the projection center (23'), and the solidified points of the sub-regions are assigned to the beam scans of these sub-regions.

2. The method according to claim 1, wherein, In the following sub-region (53), 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'), and the direction of the motion vector along the trajectory is defined such that at each solidification point the motion vector has an angle relative to the connecting vector from the solidification point to the projection center (23') of the beam (22) for the sub-region is less than a predetermined maximum angle γ1.

3. The method according to claim 1 or 2, wherein, To determine the proximity of the trajectory to the projection center (23'), a reference point connection vector (83) is established for each trajectory from a reference point on the corresponding trajectory to the projection center (23'), and the length of the component (83s) of the reference point connection vector (83) perpendicular to the trajectory is determined, wherein it is stipulated that for every two trajectories with different lengths of the component (83s) perpendicular to the trajectory, the trajectory with the smaller length of the component (83s) perpendicular to the trajectory is closer to the projection center (23') of the beam (22).

4. The method according to claim 1 or 2, wherein, In the following sub-region (53), 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'), and the motion vector at at least one fixed point has an angle greater than a predetermined minimum angle γ2 relative to the connecting vector from that fixed point to the projection center (23') of the beam (22) used.

5. The method according to claim 4, wherein, Different minimum angles γ2 are specified for different values ​​of 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 (23k) of the beam deflection center (23), the projection line (23k) of the beam deflection center (23) being a perpendicular line to the construction plane (7) that connects the projection center (23') to the beam deflection center (23).

6. The method according to claim 1 or 2, wherein, When manufacturing a three-dimensional object using the additive manufacturing equipment, airflow is guided through corresponding solidification points during scanning. In order to scan the solidified point in at least one of the sub-regions (53), a beam deflection center (23) is selected such that, for the beam deflection center, one directional component of the airflow points from the solidified point to the projection center (23') assigned to the beam deflection center (23).

7. A method for controlling an energy input device (20) of an additive manufacturing equipment to manufacture a three-dimensional object using the additive manufacturing equipment, in, The object is manufactured using the additive manufacturing equipment by applying building materials layer by layer and by solidifying the building materials in the building plane (7). The solidification of the building materials is achieved by an energy input device by supplying radiant energy to solidification points in each layer that are assigned to the cross-section of the object in that layer. The radiant energy is supplied by scanning these solidification points along multiple trajectories (54) in the building plane (7) using several beams (22) provided by the energy input device (20). Each of the plurality of beams is assigned a beam deflection center (23) above the construction plane (7), and the beam is aligned with the construction plane (7) from the beam deflection center. Each beam deflection center (23) is assigned a projection center (23') that corresponds to the vertical projection of the position of the beam deflection center (23) onto the construction plane (7). At least in one segment of the object's cross-section, the direction of the motion vectors of the plurality of beams (22) during the scanning trajectory (54) is defined such that at each solidification point in that segment, the angle of the motion vector relative to the connecting vector from that solidification point to the projection center (23') of the beam (22) used is less than a predetermined maximum angle γ1, and At least one segment of the cross-section of the object is solidified sub-region by sub-region, wherein the temporal order of scanning sub-regions (53) is defined such that sub-regions closer to the projection center (23') of the beam (22) are scanned before sub-regions further away from the projection center (23'), and the solidification points of the sub-regions are assigned to the beam scans of these sub-regions.

8. The method according to claim 7, wherein, The predetermined maximum angle γ1 is less than or equal to 135°.

9. The method according to claim 7, wherein, Different maximum angles γ1 are specified for different values ​​of 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 (23k) of the beam deflection center (23), which is a perpendicular line of the construction plane (7) that connects the projection center (23') and the beam deflection center (23).

10. The method according to claim 7 or 8, wherein, Scan at least two adjacent trajectories (54) in the same or different directions, and use different beams (22) to scan each adjacent trajectory.

11. The method according to claim 7 or 8, wherein, When manufacturing a three-dimensional object using the additive manufacturing equipment, airflow is guided through corresponding solidification points during scanning. In the at least one segment of the cross-section of the object, the direction of the motion vector of the plurality of beams (22) in the scanning trajectory (54) is defined such that a directional component of the airflow is opposite to the direction of the motion vector of the plurality of beams.

12. The method according to claim 7, wherein, The predetermined maximum angle γ1 is less than or equal to 90°.

13. A method for controlling an energy input device (20) of an additive manufacturing equipment to manufacture a three-dimensional object using the additive manufacturing equipment, in, The object is manufactured using the additive manufacturing equipment by applying building materials layer by layer and by solidifying the building materials in the building plane (7). The solidification of the building materials is achieved by an energy input device by supplying radiant energy to solidification points in each layer that are assigned to the cross-section of the object in that layer. The radiant energy is supplied by scanning these solidification points along multiple trajectories (54) in the building plane (7) using several beams (22) provided by the energy input device (20). Each of the plurality of beams is assigned a beam deflection center (23) above the construction plane (7), and the beam is aligned with the construction plane (7) from the beam deflection center. Each beam deflection center (23) is assigned a projection center (23') that corresponds to the vertical projection of the position of the beam deflection center (23) onto the construction plane (7). At least one segment of the cross-section of the object is solidified sub-region by sub-region, wherein the temporal order of scanning sub-regions (53) is defined such that sub-regions closer to the projection center (23') of the beam (22) are scanned before sub-regions further away from the projection center (23'), and the solidification points of the sub-regions are assigned to the beam scans of these sub-regions.

14. The method according to claim 13, wherein, In a sub-region (53) that defines the temporal order of scanning, at each solidification point, the angle of the motion vector relative to the connection vector from the solidification point to the projection center of the beam for that sub-region is less than a predetermined maximum angle γ1.

15. The method according to claim 13 or 14, wherein, The minimum distance from each solidified point in a sub-region to the projection center is used as a measure of the distance from the sub-region (53) to the projection center (23').

16. The method according to claim 13 or 14, wherein, The segment has multiple sub-regions (53) that have a rectangular shape in a top view on the construction plane (7). Trajectories (54) in the segment extend substantially parallel to each other and substantially parallel to the lateral side of the sub-regions. The length of a perpendicular line (93p) from the projection center to a straight line that extends through the sub-region parallel to the longitudinal side of the sub-region is used as a measure of the distance from the sub-region (53) to the projection center (23').

17. The method according to claim 16, wherein, When the cross-section of the object existing in different layers is solidified, the longitudinal sides of the plurality of sub-regions in the different layers have an orientation that changes in the construction plane.

18. The method according to claim 13 or 14, wherein, In each of the sub-regions (53) in which the scanning time sequence is defined, the motion vector at the solidification point has an angle greater than a predetermined minimum angle γ2 relative to the straight line connecting the solidification point to the projection center of the beam used.

19. The method according to claim 13 or 14, wherein, When manufacturing a three-dimensional object using the additive manufacturing equipment, airflow is guided through corresponding solidification points during scanning. In order to scan the solidified point in at least one segment of the cross-section of an object, a beam deflection center (23) is selected such that, with respect to the beam deflection center, a directional component of the airflow points from the solidified point to the projection center (23') assigned to the beam deflection center (23).

20. The method according to claim 1, 7, or 13, wherein, The method is implemented for a section having at least one solidified point, wherein when scanning the at least one solidified point, the beam deflection angle exceeds the minimum deflection angle α1, wherein the beam deflection angle is defined as the arctangent of the quotient of the distance from the solidified point to the projection center (23') and the length of the projection line (23k) of the beam deflection center (23), wherein the projection line (23k) of the beam deflection center (23) is a perpendicular line to the construction plane (7) that connects the projection center (23') and the beam deflection center (23).

21. The method according to claim 1, 7, or 13, wherein, To scan the building material along a trajectory, a beam (22) is used, the beam deflection angle α of which does not exceed a predetermined maximum deflection angle α2, 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 (23k) of the beam deflection center (23), wherein the projection line (23k) of the beam deflection center (23) is a perpendicular line to the building plane (7), which connects the projection center (23') and the beam deflection center (23).

22. The method according to claim 1, 7, or 13, wherein, For a larger value of the beam deflection angle α, a different energy input parameter value is specified compared to a smaller value 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 (23k) of the beam deflection center (23), which is a perpendicular line of the construction plane (7) connecting the projection center (23') and the beam deflection center (23).

23. The method according to claim 21, wherein, The segment is scanned using multiple beams from different beam deflection centers, and the change from one beam to another is understood as scanning a first curing point with a first beam and scanning a second curing point directly adjacent to the first curing point with a second beam, and the number of changes from one beam to another during the trajectory scanning of the segment is limited to a maximum value M.

24. The method according to claim 23, wherein, The maximum value M is determined in relation to the mass of the segment and / or the specified manufacturing time of the object.

25. The method according to claim 1, 7, or 13, wherein, The method is implemented for a segment that is at least partially part of the bottom surface region of the cross-section of an object, the bottom surface region being defined such that at least one of the p layers below the bottom surface region does not specify the curing of the building material (15), where p is a predetermined natural number, and / or the segment is at least partially part of the top surface region of the cross-section of an object, the top surface region being defined such that at least one of the q layers above the top surface region does not specify the curing of the building material, where q is a predetermined natural number.

26. The method according to claim 1, 7, or 13, wherein, The method is applied to segments that are at least partially part of the contour region of the cross-section of an object.

27. An apparatus for controlling an energy input device (20) of an additive manufacturing equipment to manufacture three-dimensional objects using the additive manufacturing equipment. in, The object is manufactured using the additive manufacturing equipment by applying building materials layer by layer and by solidifying the building materials in the building plane (7). The solidification of the building materials is achieved by an energy input device by supplying radiant energy to solidification points in each layer that are assigned to the cross-section of the object in that layer. The radiant energy is supplied by scanning these solidification points along multiple trajectories (54) in the building plane (7) using several beams (22) provided by the energy input device (20). Each of the plurality of beams is assigned a beam deflection center (23) above the construction plane (7), and the beam is aligned with the construction plane (7) from the beam deflection center. The device for controlling the energy input includes a distribution unit that assigns a projection center to each beam deflection center, the projection center corresponding to the vertical projection of the beam deflection center's position onto the construction plane. The device for controlling the energy input device includes a scanning control unit configured to specify the curing of at least one segment of the cross-section of an object in sub-regions, wherein in each sub-region (53) the trajectories (54) are substantially parallel to each other, and in at least one sub-region, the curing point of the sub-region is scanned using a beam assigned to that sub-region, the scanning order of the trajectories (54) being defined such that trajectories closer to the projection center (23') of the beam (22) are scanned before trajectories farther from the projection center (23'), and The temporal order of the scanning 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 away from the projection center (23'), and the solidified points of the sub-regions are assigned to the beam scans of these sub-regions.

28. An apparatus for controlling an energy input device (20) of an additive manufacturing equipment to manufacture three-dimensional objects using the additive manufacturing equipment. in, The object is manufactured using the additive manufacturing equipment by applying building materials layer by layer and by solidifying the building materials in the building plane (7). The solidification of the building materials is achieved by an energy input device by supplying radiant energy to solidification points in each layer that are assigned to the cross-section of the object in that layer. The radiant energy is supplied by scanning these solidification points along multiple trajectories (54) in the building plane (7) using several beams (22) provided by the energy input device (20). Each of the plurality of beams is assigned a beam deflection center (23) above the construction plane (7), and the beam is aligned with the construction plane (7) from the beam deflection center. The device for controlling the energy input includes a distribution unit that assigns a projection center to each beam deflection center, the projection center corresponding to the vertical projection of the beam deflection center's position onto the construction plane. The device for controlling the energy input device includes a scanning control unit configured such that the scanning control unit defines a trajectory (54) and the direction of the motion vectors of the plurality of beams (22) as they scan the trajectory, at least in a segment of the cross-section of the object, such that at each solidification point in the segment, the motion vector has an angle relative to the connecting vector from the solidification point to the projection center of the beam used that is less than a predetermined maximum angle γ1. The scanning control unit specifies that at least one segment of the cross-section of the object is cured sub-region by sub-region, wherein the time sequence of scanning sub-regions (53) is defined such that sub-regions closer to the projection center (23') of the beam are scanned before sub-regions farther away from the projection center (23'), and the curing points of the sub-regions are scanned using beams (22) assigned to these sub-regions.

29. An apparatus for controlling an energy input device (20) of an additive manufacturing equipment to manufacture a three-dimensional object using the additive manufacturing equipment, in, The object is manufactured using the additive manufacturing equipment by applying building materials layer by layer and by solidifying the building materials in the building plane (7). The solidification of the building materials is achieved by an energy input device by supplying radiant energy to solidification points in each layer that are assigned to the cross-section of the object in that layer. The radiant energy is supplied by scanning these solidification points along multiple trajectories (54) in the building plane (7) using several beams (22) provided by the energy input device (20). Each of the plurality of beams is assigned a beam deflection center (23) above the construction plane (7), and the beam is aligned with the construction plane (7) from the beam deflection center. The device for controlling the energy input includes a distribution unit that assigns a projection center to each beam deflection center, the projection center corresponding to the vertical projection of the beam deflection center's position onto the construction plane. The device for controlling the energy input device includes a scanning control unit configured to specify the curing of at least one segment of the cross-section of an object in a sub-regional manner, wherein the temporal order of the scanning sub-regions (53) is defined such that sub-regions closer to the projection center (23') of the beam are scanned before sub-regions farther away from the projection center (23'), and the curing points of the sub-regions are scanned using beams (22) allocated to these sub-regions.

30. An additive manufacturing apparatus for manufacturing a three-dimensional object, wherein the object is manufactured by applying building material layer by layer and by supplying radiant energy to solidification points in a building plane (7) in each layer, which are assigned to the cross-section of the object in that layer, using an energy input device, wherein the radiant energy is supplied by scanning these solidification points along multiple trajectories (54) in the building plane (7) using a plurality of beams (22) provided by the energy input device. The additive manufacturing equipment includes: Layer application device (16) is suitable for applying a layer of building material on an existing layer of building material; as well as An energy input device (20) is adapted to supply radiant energy to solidified points in each layer that are assigned to the cross-section of the object in that layer, wherein the radiant energy is supplied by scanning these solidified points along multiple trajectories (54) in the construction plane using several beams provided by the energy input device. The additive manufacturing equipment includes the equipment according to any one of claims 27 to 29 or is connected to the equipment according to any one of claims 27 to 29 in terms of signal technology.

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