Illumination strategy within cross-section

Abstract

A method of providing control data for an additive manufacturing apparatus (1), comprising: a first step (S1) of accessing model data of a plurality of partial cross-sections of an object to be manufactured, each partial cross-section comprising a sub-region of the object cross-section and a portion of an edge of the object cross-section; a second step (S2) of creating a data model of a plurality of partial cross-sections, the data model specifying a position at which the plurality of partial cross-sections are scanned along a plurality of trajectories (54) in the layer plane (7) with a plurality of light beams (22), at least one of the partial cross-sections having a set order for scanning the trajectories such that a starting trajectory is first scanned, at least one point of the starting trajectory is spaced from the edge of the object cross-section by a distance such that at least one further trajectory is located between the at least one point and the edge; and a third step (S3) of providing control data for generating the control data set.

Description

[0001] The invention relates to a method and a device for providing control data for an additive manufacturing device, a method and a suitably adapted device for controlling a suitably adapted energy input device of an additive manufacturing device, a suitably adapted additive manufacturing method and a suitably adapted additive manufacturing device as well as a suitably adapted computer program.

[0002] The invention relates to additive manufacturing devices and related methods which generally have the following features: Objects are produced layer by layer therein by solidifying amorphous build material, for example metal or plastic powder. Solidification can be achieved, for example, by irradiating the build material with electromagnetic or particle radiation, for example laser sintering (SLS or DMLS) or laser melting or electron beam melting, to supply it with thermal energy. In laser sintering or laser melting, for example, a laser beam is scanned over those positions in a layer of build material which correspond to the object cross section of the object to be manufactured in that layer, so that the build material solidifies at these positions. When the build material has been melted or sintered at a position by supplying thermal energy, the cooled build material no longer exists in an amorphous state, but rather in the form of a solid. After scanning all the positions of the object cross section, a new layer of build material is applied and likewise solidified at the positions corresponding to the object cross section in that layer.

[0003] The inventors have found that, after solidification of the build material, undesirable height differences (layer thickness deviations) occur in the positions of the layer corresponding to the object cross section, in particular when metal-containing build material is used. This unevenness makes the manufacture of high-precision objects difficult and affects the manufacturing process. It is therefore an object of the invention to provide a method and a device for generating control data for an additive manufacturing device, a method and a suitably adapted device for controlling a suitably adapted energy input device of an additive manufacturing device, a suitably adapted additive manufacturing method and a suitably adapted additive manufacturing device as well as a suitably adapted computer program, with which objects with a higher detail resolution can be obtained by a more reliable additive manufacturing process.

[0004] The problem is solved by a method for providing control data according to claim 1, a corresponding device according to claim 12, a method for controlling a suitably adapted energy input device according to claim 13, a suitably adapted additive manufacturing method according to claim 14, a suitably adapted device for controlling a suitably adapted energy input device according to claim 15, a suitably adapted additive manufacturing device according to claim 16 and a suitably adapted computer program according to claim 17.

[0005] Further embodiments of the application are set out in the dependent claims. In particular, the device according to the application can also be further developed by the features of the method according to the application as set out below or in the dependent claims, and vice versa. Furthermore, features described in connection with the device according to the application can also be used for further developing another device according to the application, even if this is not explicitly stated.

[0006] A computer-aided method according to the application for providing control data for an additive manufacturing device for manufacturing a three-dimensional object by means of the additive manufacturing device,

[0007] wherein the additive manufacturing device is configured such that the object is manufactured by the additive manufacturing device by applying a build material layer by layer and by supplying a radiation energy to positions in each layer associated with the object cross-section in the layer to solidify the build material in the layer plane, the method comprising:

[0008] a first step (S1 ) of accessing computer-based model data of a plurality of partial cross-sections of the object to be manufactured, wherein each partial cross-section comprises a sub-region of the object cross-section and a portion of an edge of the object cross-section,

[0009] a second step (S2) of generating a data model of the plurality of partial cross-sections, wherein in the data model positions are specified for scanning the plurality of partial cross-sections along a plurality of trajectories in the layer plane with a plurality of light beams,

[0010] wherein in at least one of the plurality of partial cross-sections an order of scanning the trajectories is specified such that a start trajectory is scanned first, wherein at least one point of the start trajectory is spaced apart from the edge of the object cross-section in the layer plane such that at least one further trajectory, preferably at least two further trajectories, are located between the at least one point and the edge, and

[0011] a third step (S3) of providing control data corresponding to the data model generated in the second step (S2) to generate a control data set for manufacturing the object using the additive manufacturing device.

[0012] In particular, the method can be executed entirely by a computer, which independently executes all method steps without the need for intervention by an operator.

[0013] The present invention relates to additive manufacturing devices and methods, in particular to devices and methods for selectively supplying energy in the form of electromagnetic or particle radiation to a layer of amorphous build material. Herein, the working plane (also referred to as the build plane) is the plane in which the top surface of the layer supplied with energy lies, also referred to herein as the layer plane. Herein, the radiant energy can for example be generated by a laser or an electron beam source, wherein also multiple radiation sources and / or beams can be used. The radiation supplied to the build material heats the build material, thereby causing a sintering or melting process. In particular, the present invention relates to laser sintering, laser melting and electron beam melting devices and related methods. Although the present invention can be applied both to plastic-based build materials and to metal-based build materials, the present invention has particular advantages when applied in additive manufacturing methods and devices using metal or at least metal-containing build materials, such as metal powders or metal alloy powders. In particular, the present invention can also be used for combinations of metal-based build materials and plastic-based build materials, wherein the combination comprises a mixture of metal-based build materials and plastic-based build materials, wherein also other components can optionally be included. For example, the build material can be in the form of a powder, in particular the powder particles can consist of a metal-containing core and a plastic-containing coating (or vice versa).

[0014] It is noted here that by the additive manufacturing device according to the present invention not only one object can be produced, but also multiple objects can be produced simultaneously. When the present application refers to the production of one object, it is to be understood that the corresponding description equally applies to additive manufacturing methods and devices producing several objects simultaneously.

[0015] Herein, the term "beam" does not imply that the diameter of the beam has to be very small. On the contrary, the beam can also have a larger diameter in the area of incidence on the build material (in the build plane or layer plane), in particular when the radiation is incident on the build material obliquely, or when a larger beam incidence area is intentionally generated by beam shaping when the beam is incident on the build material.

[0016] When the beam is directed onto the build material, the beam trajectory specified in the data model provides the trace of the beam in the build plane. The data model thus specifies where the beam is incident on the layer plane (the locations to be solidified) and the temporal order in which these locations in the layer plane are scanned. In the context of the present invention, a trajectory is defined as a path with a predefined directional course, which can be described by a single specific mathematical function. If the direction of the path changes, for example due to a change in the sign of the curve (i.e. a reversal of the direction), this is a new trajectory, which can be distinguished from the previously mathematically described trajectory by a different function. The beam can be directed onto the build material along the course of the trajectory, but there can also be places along the trajectory where the beam is switched off or paused. In other words, the radiation source does not necessarily have to be in the active state all the time when the scanner moves along the trajectory.

[0017] In scanning the position of the layer to be solidified, a distinction is sometimes made between an inner region of the object cross-section and an edge region (typically an edge line, whose width corresponds approximately to the diameter of the region in the build plane in which the light beam is incident on the build material perpendicular to the direction of movement of the light beam). Here, the inner region is solidified by moving the light beam along tracks which are typically substantially parallel to each other. This region can be said to be represented in hatching, so these individual tracks are also referred to as "hatch lines". In particular, in the present application the term "track" is used synonymously with "hatch line" or scan line, even though strictly speaking a track refers to a line (of zero width) specified in the control data, whereas a hatch line or scan line refers to a trace in the build plane (of non-zero width, roughly estimated to correspond approximately to the diameter of the region in the build plane in which the light beam is incident on the build material perpendicular to the direction of movement of the light beam). In order to take account of the non-zero width of the fused trace in the build plane, the tracks or hatch lines in the data model are spaced apart from each other so as to be able to input energy uniformly and without gaps into the build material when scanning the build material. In the context of the present application, preferably the hatch lines are configured as straight lines.

[0018] The edge region of the object cross-section (also referred to as the contour region) is typically solidified by moving the light beam along the run of the edge region. In contrast, the tracks referred to in the present application are lines along which the inner region of the object cross-section is scanned. The scanning of the edge region of the object cross-section can be carried out before or after the scanning of the inner region, or, in particular if the light beam used to scan the edge region is different from the light beam used to scan the inner region, the scanning of the edge region can also be carried out in time overlap with the scanning of the inner region.

[0019] The computer-based model data accessed in the first step contains a geometric description of the object (of the partial cross-section), i.e. in particular a three-dimensional CAD model, wherein further possibilities for a geometric description exist, for example a description using a parameter set and design rules. In this context, the only thing that matters is that the model data describes the geometry of at least one partial cross-section of the object to be manufactured, which partial cross-section is assigned one layer of build material, preferably exactly one layer.

[0020] Even if the second step involves generating a data model of a partial cross-section, it is understood that a data model involving multiple partial cross-sections can also be generated, i.e. according to the present application, for at least one, preferably multiple, particularly preferably all of these partial cross-sections, the position of the partial cross-section is specified in which multiple light beams are to be used to scan along multiple tracks in the layer plane. The prerequisite for this is that in the first step, the corresponding computer-based model data of these partial cross-sections is accessed. The present application includes data models in which multiple partial cross-sections are assigned to the same build material layer. However, in particular, data models relating to multiple partial cross-sections assigned to different build material layers can also be generated. If applicable, a data model of the entire object can also be generated.

[0021] A partial cross-section of an object is defined here as a subregion / subarea of an object cross-section to which a layer of build material is assigned during additive manufacturing. A further characteristic of this subregion is that it comprises a portion of the edge of the object cross-section, i.e. it adjoins a position in the layer plane which does not need to be solidified beyond the object cross-section. In a preferred embodiment of the present application, the partial cross-section according to the present application is at least predominantly separated from the other regions of the entire object cross-section by build material which does not need to be solidified. This means that the edge of the build material layer region associated with the partial cross-section adjoins build material which does not need to be solidified over at least 50%, preferably at least 75%, even more preferably at least 95%, particularly preferably 100% of its length. If the partial cross-section does not adjoin a position in the layer plane which does not need to be solidified over its entire edge, the shape and position of the partial cross-section in the layer plane can be predetermined by the person implementing the method, for example by modifying the computer-based model data, or can be defined completely automatically. In the automatic definition of the shape and position of the partial cross-section, for example, a subregion of the object cross-section which differs from the other regions of the entire object cross-section in at least one geometric property (for example, its geometric shape and / or the orientation of its geometric shape in the layer plane) can be defined as a partial cross-section. In particular, the partial cross-section can also comprise the entire cross-section of the object to be manufactured, provided that the entire cross-section is not broken down into subregions / subareas which are separate from one another (i.e. are path-connected in a mathematical sense).

[0022] It should also be noted that a partial cross-section according to the present application can only be a region which has a minimum extension in each direction in the layer plane. The minimum extension is preferably at least three times, more preferably at least five times, the distance between adjacent tracks over which the partial cross-section is solidified.

[0023] It should also be noted that the present application is advantageous regardless of the manner in which the partial cross-section is defined within the (path-connected) object cross-section.

[0024] In the present case, the starting trajectory is defined as the trajectory that first passes in time when the partial cross section is scanned.

[0025] In the present case, the distance between the starting trajectory and the edge of the partial cross section in the layer plane is defined such that at at least one point of the starting trajectory there is at least one further trajectory between the starting trajectory and the edge, preferably at least two further trajectories between the starting trajectory and the edge. Further preferably, the distance of the point of the starting trajectory to the edge is determined in a direction perpendicular to the course of the starting trajectory through the point. In particular, the point can be the starting point of the starting trajectory, i.e. the point in the starting trajectory that specifies the position in the build plane to which the beam first points when the starting trajectory is scanned. The starting point then corresponds to a two-dimensional area in the build plane or layer plane that is substantially as large as the area of incidence of the beam on the build plane.

[0026] Preferably, at at least 25% of the points of the starting trajectory to which the starting point preferably belongs, further preferably at at least 50% of the points of the starting trajectory, still further preferably at at least 75% of the points of the starting trajectory to which the starting point preferably belongs, still further preferably at all points of the starting trajectory, there is at least one further trajectory, preferably at least two further trajectories, between the starting trajectory and the edge.

[0027] The control data set can be regarded as the sum of all control data that is specified for controlling the manufacturing process in the additive manufacturing device. The control data relating to a single layer is therefore generally referred to as a layer data set. In the present application, in particular, it is assumed that the layer data set contains a data model of the position of the object cross section or object partial cross section to be solidified in a layer by one or more beams during the manufacturing process. In addition, further information about the production of the object cross section can also be included, in particular by specifying the time sequence in which the positions corresponding to the object cross section or object partial cross section are to be solidified by the scanning lines or trajectories along which the beam is to be moved, the time sequence in which the plurality of scanning lines or trajectories are scanned, or for example the layer thickness or values of illumination parameters such as the diameter or travel speed of the beam incident on the build material.

[0028] The control data provided according to the application makes it possible to achieve a more uniform thickness of the solidified build material layers in the layer-by-layer additive manufacturing process. This enables, on the one hand, the production of objects with more precise dimensions in the direction perpendicular to the layer plane, generally referred to as the z direction, and on the other hand, it prevents the disturbance of the application of the layers by protrusions of the solidified layers that can in some cases collide with the recoating element.

[0029] The inventors explain the improvements achieved as follows:

[0030] When the light beam is incident on the build material, a molten pool forms. As the light beam moves along its trajectory, this molten pool migrates through the build material, creating a melt path that, upon solidification, forms a solidified path of solidified build material. Due to surface tension formed on the surface of the molten pool, unsolidified build material in the vicinity of the molten pool is pulled into the molten pool itself. Furthermore, as long as the molten pool continues to form at the first point of incidence of the light beam, molten (unsolidified) build material is pulled from the melt path toward the first point of incidence. When the light beam first impacts the applied build material layer, more build material is available in the molten pool. Therefore, (as the light beam moves along its trajectory in the build plane) more build material is delivered to the impact location, or first melt path, than to other locations. This results in an accumulation of molten material and, consequently, a thickening of the first solidified path, particularly in the z-direction (hereinafter, the terms "build material accumulation" and "superelevation" are also used to describe this accumulation of molten material and the thickening of the solidified path in the z-direction). Subsequent cure paths thicken (rise) to a lesser extent because there is less uncured build material on the sides of the corresponding cure paths. Consequently, there will be a lack of build material in subsequent cure paths (or locations farther from the first beam impact point or the first cure path) because build material has already been transported from these cure paths (locations) to the first beam impact point or the first cure path. If, in subsequent layers, the starting trajectory (which is spaced from the edge of the associated object (partial) cross-section) is located at a different location in the build plane than in the previous layer(s), any bumps in the previous layer can be more effectively compensated.

[0031] Preferably, in the second step (S2), a data model of at least one partial cross-section in the first building material layer and a data model of at least one partial cross-section in the overlying second building material layer are generated, and for the partial cross-section in the second building material layer, a starting trajectory is selected that has the most partial overlap (preferably no overlap) with the starting trajectory of the partial cross-section of the first building material layer.

[0032] If the two starting trajectories intersect in the build plane, then there may be an overlap. Alternatively, there may be an overlap if the two starting trajectories are at least partially congruent or parallel to each other in the build plane and slightly offset from each other in the build plane. Overlap may also occur if the starting trajectories are slightly offset in the build plane, as it must be taken into account that the trajectories correspond to traces with non-zero widths in the build material. If it is assumed that the distances between the trajectories specified for the build material layers correspond to the trace widths in the build material, then there is an overlap if the offset of the starting trajectories is less than the average distance between the trajectories in one of the two build material layers (in particular, the first build material layer). Since constant values ​​are usually specified for the distances between the trajectories within a build material layer, the average distance usually corresponds to the specified constant distance.

[0033] If the starting tracks in the second build material layer overlap without lateral offset with the starting tracks in the first build material layer, there should preferably be at most half the length of the starting tracks in the first build material layer of overlap (coverage), further preferably at most 1 / 10 of overlap, particularly preferably at most 1 / 100 of the length of the starting tracks in the first build material layer of overlap. Since each starting track corresponds to a trace in the build material layer having a width corresponding to the track distance, it can also simply be said that the values given above for the maximum length of overlap of the starting tracks in the first build material layer correspond to values for the maximum area of overlap of the starting tracks in the first build material layer. If there is a lateral offset between the two starting tracks, the area of overlap of the starting tracks in the first build material layer can be calculated accordingly using the following formula:

[0034] Overlap area = overlap length x (track distance - offset)

[0035] Here it is assumed that the value of the offset is between zero and the track distance. This means that even if there is an offset of the starting tracks, and generally if the starting tracks have an arbitrary course, it can be said that there should preferably be at most half the area of the starting tracks in the first build material layer of overlap (coverage), further preferably at most 1 / 10 of overlap, particularly preferably at most 1 / 100 of the area of the starting tracks in the first build material layer of overlap.

[0036] Preferably, the starting points of the starting tracks in the second build material layer are laterally offset in the build plane relative to the starting points of the starting tracks in the first build material by an amount greater than the average distance between the tracks in the first build material layer, preferably greater than twice the average distance between the tracks in the first build material layer, more preferably greater than three times the average distance between the tracks in the first build material layer. Generally, the distance between the tracks is specified for the build material layer, so the average distance between the tracks simply corresponds to the distance specified for the build material layer.

[0037] The procedure generates a data model of a plurality of partial sections assigned to different build material layers.

[0038] Since there are elevations in the solidified build material layer in the area of the starting tracks, the elevations can superimpose in the build plane at locations where the area of the starting tracks of different build material layers lies above one another, even if a few layers are sufficient to cause such superimposition. As a result, the sum of the elevations in the upper layers can be so great that the recoating element used for this purpose collides with the elevation location when another build material layer is applied. This will result in an interruption of the build process, which can even damage the recoating element.

[0039] By not fully overlapping the starting track in the second build material layer with the starting track in the first layer, an increase in the hump caused by the first build material layer in the second build material layer can be prevented or reduced. By compensating for the hump, for example, in the first and second layers, it is also possible to prevent the manufacturing process from being impaired or interrupted.

[0040] It is further preferred that the starting tracks in more than two successive build material layers at most partially overlap, more preferably do not overlap at all. This makes it possible to even more effectively avoid large humps.

[0041] It is further preferred that the starting track in the partial cross-section of the second build material layer is chosen such that it is at a different distance from an edge of the object cross-section in the layer plane than the starting track in the partial cross-section of the first build material layer, wherein the different distances are characterized in that there is a different number of further tracks between the starting track or a point thereof and the edge.

[0042] This procedure can be used in particular if the position and orientation of the partial cross-sections in the first build material layer and the second build material layer are very similar, to ensure that the starting track in the first build material layer and the starting track in the second build material layer are offset in the build plane. This can minimize or completely prevent overlap of the starting tracks. For the starting tracks in more than two successive build material layers, it is preferred to treat them in the manner described above, wherein it is also possible to vary the distance with respect to a further build material layer following the first build material layer.

[0043] It is further preferred that the tracks in the second build material layer are rotated by an angle different from 0°, 90° and 270° with respect to the tracks in the first build material layer.

[0044] The effect of these preferred angles is that by rotating the tracks in the build material layer located above the first build material layer, the build material accumulation and build material deficiency compared to the first build material layer (or a further build material layer following the first build material layer) is modified, thereby effectively reducing the increase in the hump.

[0045] These preferred angles are particularly suitable if the first build material layer and the second build material layer are located directly above one another. If possible, the angle of rotation can also be chosen such that the starting track in the second build material layer does not overlap the starting track in the first build material layer. In general, it is preferred to choose a rotation angle such that, if the layers are rotated by this angle, the starting track in the overlying build material layer only overlaps the starting track of the first build material layer after as many layers as possible.

[0046] It should also be noted that the above angle specifications apply regardless of the direction of rotation, but it is preferred that the direction of rotation is always the same.

[0047] It is further preferred that the trajectories in the second build material layer are rotated by an angle greater than 90° and / or less than 270° with respect to the trajectories in the first build material layer.

[0048] It is even more preferred that the angle is greater than 120° or less than 120°, preferably greater than 100° and less than 140°.

[0049] The value of 120° is excluded because if the layers are rotated by 120° from layer to layer, the trajectories in the build plane in the next layer after the second build material layer are oriented the same as in the first build material layer, which is generally not desirable.

[0050] For the preferred range of angles, a particularly uniform thickness of the solidified layer area can be achieved. In particular, within this range of angles, it can be ensured that the trajectories in the successive build material layers extend as heterogeneously as possible, i.e. preferably in different directions. By making the trajectories in the successive build material layers sufficiently heterogeneous, it can generally be ensured that the starting trajectories in the subsequent build material layers only overlap with the trajectories of the previous build material layer after as many layers as possible. Within this range of angles, by rotating the trajectories, the build material accumulation and the build material deficiency in the build plane occur at different positions than in the first build material layer, so that the bulging can be effectively compensated.

[0051] Particularly preferred values of this angle are 105°, 115°, 125°, 130°, 135° or 140°.

[0052] Preferably, the starting trajectory is selected from the plurality of trajectories to be scanned in the partial cross-section using a random number generator.

[0053] As a rule, the shape of the (partial) cross-section and its position in the build plane only changes slightly (possibly not at all) between the individual build material layers. In particular in these cases, by modifying the distance between the starting trajectory and the edge in the individual layers, an increase in the bulging due to the area overlap of the starting trajectories can be avoided. This applies in particular in the case where the trajectories in the second build material layer extend substantially parallel to the trajectories in the first build material layer. Here, the random principle is used to ensure that the starting trajectories of the build material layers stacked on top of one another do not overlap or only have a small amount of overlap.

[0054] Preferably, the shape and the orientation of the trajectories in the second build material layer with respect to one another are the same as the trajectories in the first build material layer.

[0055] In this case, it is easier to select the starting trajectory in the second build material layer such that this starting trajectory overlaps as little as possible with the starting trajectory in the first build material layer.

[0056] Preferably, the individual or all subsegments of at least two, particularly preferably all, of the tracks in a partial cross section are parallel to each other. The parallelity of the tracks in one partial cross section, particularly in each of the plurality of partial cross sections, facilitates the selection of the starting track, since in this case it can be easily checked whether there is another track between the intended starting track and the edge of the object cross section. It is emphasized that parallel tracks or their subsegments are not necessarily straight. Rather, the parallelity can also exist in curved lines, particularly in the closed line course of the tracks.

[0057] Preferably, the partial cross sections are cured section by section, wherein one section corresponds to one subregion of the partial cross section and each section is cured by scanning along a plurality of tracks in the layer plane.

[0058] The sections are subregions of the partial cross section, so that during the section-wise curing the build material layer region corresponding to the partial cross section is cured subregion by subregion. Preferably, the sections have the same shape and orientation in the layer plane or build plane. It is particularly preferred that the sections have a rectangular shape, particularly a square shape. It is further preferred that the shape and orientation of the tracks in the build plane are the same in all sections and it is particularly preferred that the direction in which the tracks in the sections are scanned one after the other (succession direction of the tracks) is also the same, so that the position of the first scanned track relative to the section region is the same for all sections.

[0059] In case of a section-wise curing of the build material layer region corresponding to the partial cross section, the distance of the starting track to the edge of the object cross section can be achieved by correspondingly selecting the section of the partial cross section which is to be cured first. This applies in particular in case that the position of the first scanned track relative to the section region is the same in all sections and that the shape and orientation of these sections in the build plane are the same.

[0060] Preferably, the tracks within a section extend parallel to each other.

[0061] It is further preferred that the sections have a rectangular shape and that the tracks in these sections form an angle with the edges of these sections which is between 5° and 175°, preferably between 45° and 135°, particularly preferably between 85° and 95°.

[0062] Preferably, in this procedure straight tracks, particularly parallel tracks, are used in the individual sections. The mentioned angle refers to the angle which the starting portion or the end portion of the track (starting and end are defined by the direction of travel of the track) forms with the edge of the section. Preferably, this angle is essentially 90°, particularly exactly 90°.

[0063] It is further preferred that the track located in one of the sections is defined as the starting track,

[0064] wherein the starting trajectory is defined such that it is scanned in a direction away from the border of the segment pointing to the adjacent neighboring segment, and

[0065] wherein the first one of the trajectories to be scanned in the adjacent neighboring segment is defined such that it is scanned in a direction away from the border starting from a position adjacent to the starting trajectory.

[0066] The border between two segments is considered to be the area in the plane where the two segments adjoin. Preferably, this is a border line or edge line. The border can also be considered to be an area because there can be embodiments where the trajectories of one segment extend slightly into the other segment, or start or end at a distance from the other segment. However, the "overlap" resulting therefrom or the remaining distance to the other segment resulting therefrom is typically less than the width of the trace in the layer of build material corresponding to the trajectories, in other words less than the distance between the trajectories in the segment that are adjacent to each other.

[0067] In this context, the position adjacent to the starting trajectory is in particular a position in the neighboring segment that is at a distance from the start of the starting trajectory that is less than the width of the trace in the layer of build material corresponding to the trajectories, or less than the distance between the adjacent trajectories in the segment in which the starting trajectory is located.

[0068] This is intuitively clear for trajectories that are perpendicular to the border when scanning the trajectories in a direction away from the border. If the trajectories form an angle with the border that is not 90°, then there is at least one directional component away from the border when scanning away from the border.

[0069] The inventors interpret the advantage of this procedure by the fact that scanning the starting trajectory in the area of the neighboring segment next to the starting trajectory results in a lack of build material. If this area is the first area in the neighboring segment that is scanned, then the lack of build material will be compensated by the fact that during solidification of this area, build material that is not yet solidified adjacent to this area will also solidify, or build material that is already solidified adjacent to this area will melt again and be pulled into this area.

[0070] It is further preferred that in the segment in which the starting trajectory is located and in the adjacent neighboring segment, all trajectories are scanned in the same direction. This means that the start of all trajectories is preferably located at or near the border between these two segments. This procedure can take into account the fact that bulges often occur at the start of a trajectory.

[0071] According to the invention, a device for providing control data for an additive manufacturing device for manufacturing a three-dimensional object using the additive manufacturing device,

[0072] wherein the additive manufacturing device is configured such that an object is manufactured by the additive manufacturing device by applying a build material layer by layer and by supplying a radiant energy to locations in each layer assigned to an object cross section in the layer to solidify the build material in the layer plane, the device comprising:

[0073] an access unit configured to access computer-based model data of a plurality of partial cross sections of the object to be manufactured, wherein each partial cross section comprises a sub-region of an object cross section and a portion of an edge of the object cross section,

[0074] a data model generation unit configured to generate a data model of the plurality of partial cross sections, wherein the data model specifies locations of the plurality of partial cross sections to be scanned along a plurality of trajectories in the layer plane with a plurality of light beams,

[0075] wherein the data model generation unit is configured to define, in at least one of the plurality of partial cross sections, an order of scanning the trajectories such that a start trajectory is scanned first, wherein at least one point of the start trajectory is spaced apart from an edge of the object cross section in the layer plane such that at least one further trajectory, preferably at least two further trajectories, are located between the at least one point and the edge, and

[0076] a control data provision unit configured to provide control data corresponding to the data model generated by the data model generation unit to generate a control data set for manufacturing the object using the additive manufacturing device.

[0077] The data model generated by the data model generation unit for generating the control data set can be provided by the control data provision unit itself by integrating the generated data model into the control data set of the additive manufacturing device. However, the provision also includes forwarding the data model to a data processing device which integrates the data model into the control data set or forwarding the data model directly to the additive manufacturing device. In particular, the data model of an object cross section which has not yet been manufactured can be dynamically provided to the additive manufacturing device during the manufacturing process of the additive manufacturing device.

[0078] In a method for controlling an energy input device of an additive manufacturing device for manufacturing a three-dimensional object using the additive manufacturing device according to the present application,

[0079] wherein the object is manufactured by the additive manufacturing device by applying a build material layer by layer and by supplying a radiant energy to locations in each layer assigned to an object cross section in the layer to solidify the build material in the layer plane,

[0080] wherein the additive manufacturing device comprises an energy input device for supplying radiant energy, the energy input device being configured to solidify a plurality of partial cross sections of an object to be manufactured by scanning positions of the plurality of partial cross sections along a plurality of trajectories in the layer plane with a plurality of light beams, wherein each partial cross section comprises a sub-area of an object cross section and a portion of an edge of the object cross section,

[0081] for at least one of the plurality of partial cross sections, a sequence of scanning the trajectories is defined such that a starting trajectory is scanned first, wherein at least one point of the starting trajectory is spaced apart from the edge of the object cross section in the layer plane such that at least one further trajectory is located between the at least one point and the edge, preferably at least two further trajectories are located between the at least one point and the edge.

[0082] In order to scan the build material along the trajectories, the energy input device can particularly comprise a plurality of light beam deflection devices (e.g. galvanometer scanners) by which light from a radiation source (e.g. a laser) is directed to the desired positions in the build plane, wherein the movement speed of the one or more light beams over the build plane is also controlled via these light beam deflection devices. In particular, the method for controlling the energy input device can be implemented by processing the control data set generated with the control data provided according to the method for providing control data according to the present application.

[0083] In an additive manufacturing method for manufacturing a three-dimensional object with an additive manufacturing device according to the present application, the method for controlling an energy input device of an additive manufacturing device according to the present application is performed.

[0084] Preferably, this is a manufacturing method using a metal-based build material, i.e. a build material with a metal content of more than 50% by weight, for example a metal powder or a metal alloy powder, such as a steel powder or a powder containing chromium, titanium, tungsten, cobalt, nickel, copper or aluminum, wherein the list of elements is not exhaustive. However, in particular, a combination of a metal-based build material and a plastic-based build material can also be used, wherein the combination consists of a mixture of a metal-based build material and a plastic-based build material and optionally can also include further components. For example, the build material can be in the form of a powder, in particular the powder particles can consist of a metal-containing core and a plastic-containing coating (or vice versa). Preferably, the additive manufacturing method is a laser sintering method or a laser melting method.

[0085] According to the present application, a device for controlling an energy input device of an additive manufacturing device for manufacturing a three-dimensional object with the additive manufacturing device,

[0086] wherein the object is manufactured by the additive manufacturing device by applying a build material layer by layer and by supplying a radiation energy to locations of object cross sections assigned to the object cross sections in each layer to solidify the build material in the layer plane,

[0087] wherein the additive manufacturing device comprises an energy input device for supplying the radiation energy, the energy input device being configured to solidify the plurality of partial cross sections by scanning the locations of the plurality of partial cross sections along a plurality of trajectories in the layer plane using a plurality of light beams, wherein each partial cross section comprises a sub-area of an object cross section and a portion of an edge of the object cross section,

[0088] The device comprises a scan control unit configured to, for at least one of the plurality of partial cross sections, specify an order of scanning the trajectories such that a start trajectory is scanned first, wherein at least one point of the start trajectory is spaced apart from an edge of the object cross section in the layer plane such that at least one further trajectory, preferably at least two further trajectories, are located between the at least one point and the edge.

[0089] The control device of the energy input device can implement the above-described method for controlling an energy input device. The individual components of the device, in particular the scan control unit, or the entire control device, can be implemented by software only or by hardware only or by a mixture of hardware and software. The interfaces do not necessarily have to be configured as hardware components, but can also be implemented as software modules. The interfaces can also consist of hardware components and software components, for example in the form of a standard hardware interface and a special configuration for a specific application by means of software. In addition, several interfaces can also be combined into a common interface, for example an input and output interface.

[0090] In particular, the control device can be a unit within a control unit for controlling the manufacturing process in the additive manufacturing device. However, it is emphasized that the control device can also exist outside the control unit in the same way and can exchange signals with the additive manufacturing device, in particular the energy input device, via a network. In particular, if the control device is implemented by software only, the control device can be in the form of a computer program. Preferably, such a computer program for the manufacturing process is then executed by the additive manufacturing device in its control unit.

[0091] The additive manufacturing device for manufacturing a three-dimensional object by an additive manufacturing device according to the invention comprises a device for controlling an energy input device of the additive manufacturing device according to the invention.

[0092] Preferably, the additive manufacturing device is configured to manufacture objects from a metal-based build material, wherein the metal content exceeds 50% by weight of the build material, for example a metal powder or a metal alloy powder, such as a steel powder or a powder containing chromium, titanium, tungsten, cobalt, nickel, copper or aluminum, wherein the list of elements is not exhaustive. In particular, the additive manufacturing device can be configured to manufacture objects from a combination of a metal-based build material and a plastic-based build material, wherein the combination consists of a mixture of a metal-based build material and a plastic-based build material, wherein further components can optionally be included. For example, the build material can be in the form of a powder, in particular the powder particles can comprise a metal-containing core and a plastic-containing coating (or vice versa). Preferably, the additive manufacturing device is a laser sintering device or a laser melting device.

[0093] The computer program according to the present application comprises a series of instructions which, when executed, implement the computer-aided method for providing control data for an additive manufacturing device according to the present application, and / or the method for controlling an energy input device of an additive manufacturing device according to the present application, or the additive manufacturing method for manufacturing a three-dimensional object by means of an additive manufacturing device according to the present application.

[0094] The computer program for implementing the method for providing control data according to the present application can be executed on a computer or data processor which is completely independent of the additive manufacturing device, in particular which cannot exchange data with the additive manufacturing device. It is of course advantageous if the instructions of the computer program are executed by a data processor which is integrated in the additive manufacturing device or which cooperates with the additive manufacturing device. The implementation of the method for providing control data according to the present application and the related devices by means of software makes it easy to install on different computer systems at different locations, for example at the creator of the object design or at the operator of the additive manufacturing device.

[0095] Preferably, the computer program for implementing the method for controlling an energy input device according to the present application or the additive manufacturing method according to the present application is executed on a data processor which is integrated into the additive manufacturing device or which interacts with the additive manufacturing device. The term "interacts" mentioned several times above means that the data processor can exchange data with the additive manufacturing device, for example via a radio network or via a data line.

[0096] Figure 1 A schematic view of an exemplary device for additive manufacturing of a three-dimensional object according to the present application is shown, partly in cross-section.

[0097] Figures 2a to 2c The term "partly in cross-section" used in this application is explained.

[0098] Figure 3 An example of a procedure for specifying a starting trajectory according to the present application is shown schematically.

[0099] Figure 4 Another example of a procedure for specifying a start trajectory is schematically shown.

[0100] Figures 5a to 5c For explaining the possibility of defining a distance between a start trajectory and an edge of an object cross section.

[0101] Figures 6a to 6c For illustrating a procedure for specifying a start trajectory in several layers.

[0102] Figure 7 A sequence of the method for providing control data according to the application is schematically shown.

[0103] Figure 8 The structure of the apparatus for providing control data according to the application is schematically shown.

[0104] Figure 9a and Figure 9b Another example of a procedure for specifying a start trajectory in several layers is shown.

[0105] Figure 10a and Figure 10b A variant of the procedure according to Figure 4 is shown.

[0106] With reference to Figure 2a , Figure 2b and Figure 2c , the term "partial cross section" used in this application is first explained in more detail. Figure 2a An exemplary object 200 to be produced by means of additive manufacturing is shown. Figure 2b The entire cross section 280 through the object 200 in a plane A is shown in Figure 2a During additive manufacturing, a layer of build material is assigned to the cross section 280, and therefore, the plane A is chosen to be parallel to this layer of build material. As can be seen from Figure 2b , the entire cross section 280 comprises eight mutually separate sub-areas 281, 282, 283, 284, 285, 286, 287, 288. Each of these sub-areas can be regarded as a partial cross section completely separate from the other areas of the entire cross section 280. Figure 2c An exemplary object 210 to be also produced by means of additive manufacturing is shown, as well as the entire cross section 290 through the object 210 in a plane B. As in the case of the object cross section 280, during additive manufacturing, a layer of build material is assigned to the cross section 290, and therefore, the plane B is chosen to be parallel to this layer of build material. As can be seen from Figure 2cAs can be seen, the four sub-areas 291, 292, 293 and 294 in the entire cross-section 290 differ from each other in their geometric properties. Sub-area 291 is approximately rectangular except for the two semicircular protrusions at the edges. Sub-area 292 is a circular arc. Sub-area 293 is a mirror image of sub-area 292 along a horizontal straight line in the drawing plane, having the same shape and the same area as sub-area 292, but sub-area 293 differs from sub-area 292 in that it has a different sign of curvature in plane B. In addition, each of the sub-areas 291, 292, 293, 294, which together form the object cross-section 290, is contiguous with build material that does not need to be solidified. According to the present invention, only sub-area 291 is considered a partial cross-section, because it is the only one of the sub-areas that has a minimum extension that is more than five times the distance between the trajectories in the sub-area. To illustrate this fact, Figure 2c Exemplary trajectories in each sub-area are shown in the cross-section. In sub-area 291, a plurality of concentric trajectories can be seen, whereas in sub-areas 292, 293 and 294, there is only one trajectory each (trajectories 2992, 2993, 2994).

[0107] For describing the present invention, reference will first be made in the following to Figure 1 An additive manufacturing apparatus according to the present invention is described by way of example with a laser sintering apparatus or a laser melting apparatus.

[0108] For building the object 2, the laser sintering or laser melting apparatus 1 comprises a process chamber or build chamber 3 having a chamber wall 4. In the process chamber 3, a build container 5 is arranged which opens towards the top and has a container wall 6. The upper opening of the build container 5 defines a working plane 7 (also referred to as build plane), wherein the area of the working plane 7 which is located within this opening and which can be used for building the object 2 is referred to as build area 8.

[0109] A support 10 which can be moved in a vertical direction V is arranged in the build container 5 to which a base plate 11 is attached which closes the container 5 at the bottom, thus forming the bottom of the container. The base plate 11 can be a plate which is formed separately from the support 10 and which is attached to the support 10, or the base plate can be formed integrally with the support 10. Depending on the powder used and the process, a build platform 12 can also be attached to the base plate 11 as a build base on which the object 2 is built. However, it is also possible to build the object 2 on the base plate 11 itself, which in turn serves as a build base. In Figure 1 In the cross-section, the object 2 to be formed in the container 5 on the build platform 12 is shown in an intermediate state below the working plane 7, wherein several solidified layers are surrounded by un-solidified build material 13.

[0110] Laser sintering or melting device 1 further comprises a storage container 14 for a building material 15 (in this example, a powder) that can be solidified by electromagnetic radiation, and a reapplicator 16 that can be moved in a horizontal direction H to apply building material 15 to building area 8. Optionally, a heating device, such as a radiant heater 17, can be arranged in process chamber 3 for heating the applied building material. Radiant heater 17 can be, for example, an infrared radiator.

[0111] The exemplary additive manufacturing device 1 further comprises an energy input device 20 having a laser 21, which generates a laser beam 22, which is deflected via a beam emitter 23 (e.g. one or more galvanometer mirrors and associated drives) and focused by a focusing device 24 via a coupling window 25 in the chamber wall 4 attached to the upper side of the process chamber 3 onto the working plane 7. Figure 1 Although not shown in the figure, the additive manufacturing apparatus may include two or more beam emitters 23. This allows the manufacturing process to be completed in a shorter time because several beams can be used to scan and solidify the build material at different locations simultaneously.

[0112] Figure 1 The specific design of the laser sintering or laser melting device shown is merely exemplary for the present invention and can of course also be modified, in particular when using energy input devices other than those shown.

[0113] The laser sintering device 1 further includes a control unit 29, which controls the various components of the device 1 in a coordinated manner to perform the building process. Alternatively, the control unit may be partially or completely external to the additive manufacturing device. The control unit may include a CPU whose operation is controlled by a computer program (software). The computer program may be stored in a storage device separate from the additive manufacturing device, and then loaded from the storage device (e.g., via a network) into the additive manufacturing device, and in particular, into the control unit.

[0114] During operation, the control unit 29 lowers the support 10 layer by layer, controls the recoater 16 to apply a new powder layer, and controls the energy input device 20, i.e. in particular the beam emitter 23 and possibly the laser 21 and / or the focusing device 24, to solidify the respective layer at the positions corresponding to the respective object by scanning these positions with the laser. In the present application, reference is made to a unit 39 within the control unit 29, which is responsible for controlling the energy input device 20 as the control device 39 of the energy input device. However, it should be emphasized that the control device 39 of the energy input device can also be present outside the control unit 29 in the same way (also in the form of a computer program), as long as it is ensured that the control device 39 of the energy input device is able to fully cooperate with the control unit 29 for the additive manufacturing of the object, i.e. in particular is able to exchange signals with the control unit 29.

[0115] In the additive manufacturing device described above as an example, the manufacturing process is carried out in such a way that the control unit 29 or the control device 39 of the energy input device processes a control data set. The control data set is used to specify at each point in time during the solidification process the energy input device (in particular, the deflection device 23 in the case of the laser sintering or laser melting device described above) at which position the radiation is to be directed to the working plane 7.

[0116] Figure 8 FIG1 shows an apparatus 100 for providing control data for an additive manufacturing apparatus. The apparatus comprises a data access unit 101, a data model generating unit 102 and a control data providing unit 103. Figure 7 The operating mode of the apparatus 100 for providing control data is described by way of example.

[0117] exist Figure 8 In the device 100 for providing control data for an additive manufacturing device, the data access unit 101 first accesses computer-based model data of an object. Figure 7 In the processing sequence shown, this data access step is the first step S1. The computer-based model data contain a geometric description of the object, i.e., in particular a three-dimensional CAD model, although other geometric descriptions are also possible, such as descriptions using parameter sets and design rules. In this context, it is only important that the model data describe the geometry of at least one partial cross-section of the object to be manufactured, to which a layer of building material is assigned. In other words, the data access unit 101 can also access the entire model data (complete CAD model) of the object to be manufactured (or multiple objects to be manufactured, if multiple objects are to be manufactured in parallel in the additive manufacturing device).

[0118] The data access step (first step S1) can also comprise forwarding the model data to the data model generation unit 102 described below, but the data model generation unit 102 can also obtain this data from the data access unit 101 or read this data from a memory not shown in Figure 8 which the data is stored.

[0119] In the second step S2 shown in Figure 7 , the data model generation unit 102 now specifies a data model in which the solidification of the positions of the build material layer assigned to the at least one partial cross section, which correspond to the at least one partial cross section, is defined in a chronological order corresponding to the movement of the light beam along the trajectory on the build material. Here, in particular, a chronological order is specified in which the trajectory is traversed sequentially.

[0120] After the generation of the at least one data model in the second step S2 in Figure 7 , the control data providing unit 103 shown in Figure 8 then provides control data for generating a control data set (in Figure 7 , this is step S3). Here, the data model generated in the second step S2 can be provided as control information (control data) or the data model is reformatted for better integration into the control data set.

[0121] Examples of the procedure in the second step S2 are described below for different (partial) cross sections and course of the trajectory.

[0122] The schematic Figure 3 shows an exemplary partial cross section 30 which is identical to the entire cross section of the object and has an elliptical outer edge 31 towards build material which does not need to be solidified and an elliptical inner edge 32 towards build material which does not need to be solidified. In order to solidify the area between these two edges, the curved edges make it advisable not to move the light beam along a straight trajectory, but along a curved trajectory, as shown by reference numerals 301 to 309 in Figure 3 . In this example, since these trajectories have a shape which adapts to the shape of the edges 31 and 32, the number of trajectories required to scan the cross section area is less than in the case of choosing straight trajectories.

[0123] The procedure according to the application is characterized in that, when scanning the build material, the trajectory which is to be scanned first in time is not the trajectory 303 or 309 which is closest to one of the edges 31, 32 (edge trajectory), but a trajectory which is spaced apart from the edge. In Figure 3In FIG, the track 301 (starting track) where the scan occurs first in time is represented by a solid line to distinguish it from other tracks. As can be seen from the figure, the two tracks 302 and 303 scanned after the starting track 301 are located between the starting track 301 and the edge 31. Figure 3 The reference numerals in are selected in such a way that the tracks with higher reference numerals pass after the tracks with lower reference numerals.

[0124] Of course, according to the present invention, a trajectory other than trajectory 301 may also be selected as Figure 3 , for example, trajectory 307. It is only important that the starting trajectory is not the trajectory closest to the edge. Although in the most general method of the invention it is sufficient that at least one point of the starting trajectory (in particular the starting point) is spaced from the edge, in this example it is possible to define a starting trajectory in which all points are spaced from the edge.

[0125] Figure 4 Another example of the procedure in the second step S2 is shown. The exemplary partial cross section 40 has a rectangular shape, which in this example corresponds to the entire cross section of the object to be manufactured by additive manufacturing. Figure 3 In contrast, the building material in the building material layer area assigned to the cross section is not scanned using a trajectory that passes through the entire cross section. Instead, the scanning is performed segment by segment by defining segments (each segment corresponding to a cross section sub-area). Figure 4 Rectangular segments 401, 402, 403, 404 and 405 are shown by way of example. As shown in segment 401, the area of ​​each segment is scanned along trajectories 91, 92, 93, 94 and 95. In this case, the order in which the trajectories are scanned within the individual segments is typically chosen to be the same in all segments. Figure 4 , the trajectory is scanned from top to bottom (in the drawing plane) in each segment. Figure 4 This is illustrated in FIG401 where the trajectory to be scanned first in each segment is shown as a solid line, while the trajectory that follows in time is shown as a dashed line. Thus, for segment 401, trajectory 91 is scanned first, then trajectory 92, then trajectory 93, then trajectory 94, then trajectory 95. Although in Figure 4 In the embodiment, the tracks within a segment are perpendicular to the edge of the segment, i.e. form a 90° angle with the edge of the segment, but the tracks may also form a different angle with the edge of the segment, such as a 45° angle, but an angle of substantially or exactly 90° is preferred.

[0126] If segmented scanning is selected to scan a region of the building material layer corresponding to a (partial) cross section, the procedure according to the invention can be implemented in such a way that a segment within the cross section is first scanned, in which the trajectory in the segment scanned first in time is spaced apart from the edge of the cross section. This trajectory is therefore the starting trajectory when scanning the (partial) cross section. Correspondingly, in Figure 4 In the example shown, segment 401 is scanned first, followed by segments 402, 403, 404, and 405 in the order of the reference numerals. Alternatively, segments 402 and 403 could be scanned first, but segments 404 and 405 could not be scanned first because, in these two segments, the trajectory to be scanned first in time is adjacent to edge 41. To clearly indicate that trajectory 91, which is to be scanned first in time in segment 401, is the starting trajectory of section 40, trajectory 91 is shown with a thicker line.

[0127] Figure 10a and Figure 10b An exemplary embodiment is shown of how to advantageously define a trajectory to be scanned in two adjacent segments in order to avoid bulging in thickness of the solidified layer that occurs during solidification of a cross section of an object.

[0128] Figure 10a A top view of a cross section 1000 of an object manufactured by additive manufacturing is shown, the object having an exemplary circular shape with an outer edge 1100. Figure 4 As in the example in Figure 10a In the example in , the build material is scanned segment by segment. Figure 4 As in FIG, for clarity, only those segments that need to be scanned to achieve solidification of the build material corresponding to cross section 1000 are shown. Figure 4 Same as in Figure 10a The two segments 1001 and 1002 shown have a rectangular shape, wherein the trajectory along which the area of ​​each segment is scanned is again indicated by arrows. In each segment, the trajectory that is scanned first in time in this segment is represented by a solid line, in segment 1001 this is trajectory 1021 and in segment 1002 this is trajectory 1020, while the trajectories that follow in time are represented by dashed lines. Figure 10a In the example of FIG, segment 1002 is solidified first in the object cross section, so trajectory 1020 is the starting trajectory of cross section 1000 and is represented by a thicker line for identification purposes.

[0129] In accordance with Figure 10aIn the procedure shown, it can be first seen that in segment 1001, track 1021 is scanned first, with its starting point 1021a immediately adjacent to the starting point 1020a of starting track 1020. In addition, track 1021 in segment 1001 is traversed in the opposite direction to the starting track. Such a procedure can be used to ensure that material accumulated at the starting point of the starting track is at least partially transported away by scanning the first track in the adjacent segment, thereby reducing layer bulge.

[0130] Figure 10b Shown according to Figure 10a Modifications of the procedure of Figure 10b In the procedure, all trajectories in segments 1001, 1002 are scanned in the same direction. In addition, all trajectories start from the boundary 1012 between the two segments 1001 and 1002. In this way, the layer ridges that often appear at the beginning of the trajectories in the first scanned segment 1002 can be at least partially eliminated.

[0131] refer to Figures 5a to 5c , a possible definition of the distance between the starting trajectory and the edge of the partial section is explained below. For this purpose, Figures 5a to 5c In each case a partial cross section 50 is shown which, for simplicity, is identical to the entire cross section of the object, being square as an example and having an edge 51 . Figure 5a In FIG, four trajectories 501, 502, 503, and 504 are shown in a partial cross-section 50, with trajectory 501 being defined as the starting trajectory and therefore represented by a thicker line. The figure also shows three subsegments 510, 511, and 512 of starting trajectory 501. It can be seen that, perpendicular to the direction of subsegment 510, two additional trajectories 502 and 503 lie between subsegment 510 and edge 51 of object cross-section 50. Furthermore, perpendicular to the direction of subsegment 511, three additional trajectories 502, 503, and 504 lie between subsegment 511 and edge 51 of object cross-section 50. Finally, perpendicular to the direction of subsegment 512, another trajectory 502 lies between subsegment 512 and edge 51 of object cross-section 50. Therefore, according to the present invention, trajectory 501 can be defined as the starting trajectory because at least one subsegment of trajectory 501 satisfies the requirement that at least one additional trajectory exists between the starting trajectory and the edge.

[0132] Figure 5a For the purpose of explaining the preferred case, in which the distances of the sub-segments or points of the starting track from the edge are determined in a direction perpendicular to the direction of the sub-segments or the direction of the starting track through these points, it is not absolutely necessary to determine the distances in this way, and reference will be made to Figure 5b and Figure 5c Provide explanation. Figure 5bA starting trajectory 505 and two further trajectories 555 and 556 are shown. The trajectories 555 and 556 are located between the starting point 550 of the starting trajectory 505 and the edge 51 of the object cross section 50. In particular, the trajectories 555 and 556 are located between the starting point 550 of the starting trajectory 505 and the edge 51 of the object cross section 50 in a direction parallel to the course of the starting trajectory (more precisely, in the direction of the course of the initial portion of the starting trajectory). In Figure 5a In the example of Fig. 5, the distance between a linear subsection of the starting trajectory and the edge is determined, but here the distance of a single point (in this case the starting point) of the starting trajectory to the edge is determined. In Figure 5b In Fig. 5, according to the present application, the trajectory 505 can be defined as a starting trajectory, since there is at least one further trajectory between at least one point (here the starting point) of the starting trajectory and the edge. As Figure 5b is shown, the trajectories 555 and 556 are neither parallel nor perpendicular to each other. Furthermore, the trajectories 555 and 556 are neither parallel nor perpendicular to the starting trajectory 505.

[0133] Figure 5c A starting trajectory 506, a circular-arc-shaped subsection 560 of the starting trajectory 506, and trajectories 565 and 566 are shown. The trajectories 565 and 566 are located between the subsection 560 of the starting trajectory 506 and the edge 51 of the object cross section 50. In particular, the trajectories 565 and 566 are located between the subsection 560 of the starting trajectory 506 and the edge 51 of the object cross section 50 in a radial direction of the subsection 560 (with respect to the circular-arc shape) of the starting trajectory. According to the present application, the trajectory 506 can thus be defined as a starting trajectory, since there is at least one point (here even multiple points, namely the subsection 560) that fulfills the condition that there is at least one further trajectory between the starting trajectory and the edge. As Figure 5c is shown, the trajectories 565 and 566 are neither parallel nor perpendicular to each other. Furthermore, the trajectories 565 and 566 are neither parallel nor perpendicular to the course (of the circular-arc shape) of the subsection 560 of the starting trajectory 506.

[0134] As shown with reference to Figure 5a , Figure 5b and Figure 5c , for embodiments of the present application, the direction of the further trajectory located between the edge and the starting trajectory with respect to the direction of the course of the starting trajectory is irrelevant. The direction of the course of the further trajectory located between the point or subsection of the starting trajectory and the edge also has no influence on embodiments of the present application.

[0135] Even though the uniformity of the solidified layer thickness can be improved by the procedure of the present application, the maximum thickness of the solidified build material layer within a partial cross-section usually still occurs in the area of the start trajectory. Since the object to be manufactured usually has many object cross-sections stacked on top of each other (corresponding to many build material layers stacked on top of each other), the increase in the excessive thickness in the individual layers can lead to an undesirably large deviation in the overall height of the object (extending in the z-direction). In particular, this height deviation can already be so large during the manufacturing process that the recoating element collides with protrusions of solidified build material protruding upwards from already solidified layers. This undesirably behavior can be countered by the procedure described below with reference to Figures 6a to 6c

[0136] Figure 6a A top view of a cross-section 60 of an object manufactured using additive manufacturing is shown, which cross-section has a circular shape and for example comprises an outer edge 61. As in the example in Figure 4 , in the example in Figure 6a , the build material is scanned in segments. As in Figure 4 , for the sake of clarity, only some of the segments are shown which need to be scanned in order to achieve the solidification of the build material corresponding to the cross-section 60. As in Figure 4 , the two segments 601 and 602 shown have a rectangular shape, wherein the trajectories along which the area of each segment is scanned are again indicated with arrows. In each segment, the trajectory which is scanned first in time in the segment is indicated in solid line, which is trajectory 691 in segment 601 and trajectory 692 in segment 602, while the trajectory which is scanned later in time is indicated in dashed line. Since segment 601 is solidified first in the example in Figure 6a , trajectory 691 is the start trajectory of cross-section 60 and is indicated with a thicker line for identification purposes.

[0137] Figure 6b A top view of another cross-section 60' of the same object involved in Figure 6a is shown. Here, cross-section 60' involves a position higher in the z-direction than the position involved in cross-section 60 in Figure 6a . In other words, with respect to the orientation of the object in space during its manufacture, Figure 6b , the height at which cross-section 60' of Figure 6a is higher than cross-section 60 of Figure 6a . Therefore, cross-section 60' is assigned a build material layer which is located above the build material layer assigned to cross-section 60 of

[0138] For the sake of simplicity, Figure 6b , cross-section 60' in Figure 6a has the same shape and size as cross-section 60 in Figure 6b .​Figure 6b Segments 601' and 602' have the same Figure 6a The segments 601 and 602 in FIG. 6 are of the same shape and size. However, it can be seen that Figure 6a Compared to the segment in , segments 601' and 602' are rotated 25° clockwise. Other possible rotation angles are, for example, 45°, 65°, 85°, 105°, 115°, 125°, 135°, 155°, and 175°. This also applies to the tracks in segments 601' and 602', such as the track 691' that solidifies first in time in segment 601' and the track 692' that solidifies first in time in segment 602'. Figure 6b , track 692' is the starting track.

[0139] Figure 6c Shown Figure 6a The cross section 60 and Figure 6b Section 60' and Figure 6a and Figure 6b 6 shows a top view of the superposition of segments and trajectories shown in . It can be seen in the superposition that the trajectory 691' which is scanned first in time in the segment 601' of the cross section 60' overlaps with the starting trajectory 691 of the cross section 60. If the segment 601' in the cross section 60' is solidified first, the trajectory 691' will become the starting trajectory of the cross section 60'. The increase in layer thickness will then be accumulated at the point where the starting trajectories 691 and 691' overlap. Depending on the application, the accumulation of the increase in layer thickness in a small area (in the hypothetical example, the starting trajectories 691 and 691' intersect at only one point) may be acceptable. However, for some applications, the presence of an overlap of the starting trajectories may be disadvantageous or undesirable, in particular when the layers 60 and 60' are separated by only a small number of further layers (for example less than 64 layers, preferably less than 32 layers, particularly preferably less than 16 layers). Therefore, the example of FIG. 6 provides that in the cross section 60', the segment 602' is solidified first, whereby the trajectory 692' becomes the starting trajectory of the cross section 60', as Figure 6b shown.

[0140] Figure 9a and Figure 9b Another exemplary procedure is shown. Figure 9a and Figure 6a is very similar and shows a top view of a cross section 90 of an object manufactured using additive manufacturing, the cross section being circular in shape and having, for example, an outer edge 91. Figure 6a As in the example in Figure 9a In the example in , the build material is scanned segment by segment. Figure 6a Again, for clarity, only those segments that need to be scanned to achieve solidification of the build material corresponding to section 90 are shown. Figure 6a Same as in Figure 9aThe two segments 901 and 902 shown have a rectangular shape, wherein the trajectory along which the area of ​​each segment is scanned is again indicated by arrows. In each segment, the trajectory scanned first in time is represented by a solid line, in segment 901 this is trajectory 991 and in segment 902 this is trajectory 992, while the trajectories scanned later in time are represented by dashed lines. Figure 9a In the example shown, segment 901 is cured first, so trajectory 991 is the starting trajectory of section 90 and is shown with a thicker line for identification purposes.

[0141] Figure 9b Shown through Figure 9a Here, the cross section 90' relates to a cross section 90' of the object in the z direction. Figure 9a The section 90 in FIG. 1 relates to a higher position. In other words, relative to the orientation of the object in space during manufacture, Figure 9b The height of the section 90' is higher than Figure 9a Thus, section 90' is assigned a layer of building material that is located between the layers assigned to Figure 9a A cross section 90 is provided above the build material layer.

[0142] For simplicity, in this example, Figure 9b The cross section 90' has the same Figure 9a The cross-section 90 is of the same shape and size, and Figure 9b Segments 901' and 902' have the same Figure 9a In addition, the positions and orientations of segments 901' and 902' and the trajectories therein in the construction plane or layer plane are also the same as Figure 9a Segments 901 and 902 in the cross-section 90 and the trajectories therein are identical. However, when curing cross-section 90', trajectory 991' is not selected as the starting trajectory (and therefore segment 901' is not selected as the starting segment), but trajectory 992' is selected (and therefore segment 902' is selected as the starting segment). This is because if trajectory 991' were selected as the starting trajectory, it would completely overlap with starting trajectory 991 of the lower cross-section 90 during curing, resulting in cumulative layer bulges.

[0143] As Figure 9b Alternatively to the procedure shown in , it is also possible to avoid or reduce the overlap of the starting trajectories by spatially offsetting (without rotating) segments 901′ and 902′ and / or the trajectories contained therein relative to segments 901 and 902 and / or the trajectories contained therein in the layer plane or the construction plane. Depending on the degree of the offset, the (now spatially offset) trajectory 991′ can serve as the starting trajectory.

[0144] Finally, it is also possible to use a random number generator to select a starting trajectory from the trajectories in a layer, in particular the second layer after the first layer. In particular when the segment pattern and / or the trajectory pattern in successive layers is the same and / or has the same orientation in the build plane, this procedure can be selected.

[0145] In particular when the sections of the partial cross-sections in the successively stacked build material layers are scanned section by section, changing the orientation (rotation) of the trajectories in the layer plane or build plane can sometimes already ensure that the starting trajectories in the different build material layers do not overlap (not at any position) even if the scanning order of the segments in the different layers is the same.

[0146] In general, it is advantageous if the position and orientation of the trajectories in the plane is different in different layers, since this counteracts the formation of anisotropies or preferential directions in the manufactured object. If the orientation of the trajectories in the build material layers stacked on top of each other is the same, the trajectories in these layers preferably do not directly stack on top of each other, but are offset horizontally from each other, in particular in a direction perpendicular to the direction of the trajectories' course.

[0147] One simple way of preventing anisotropies is to change the orientation of the trajectories in the respective subsequent layer or at least in every second layer. Assuming that the shape of the trajectories does not change between the layers, a change in the orientation of the trajectories corresponds to a rotation of the build plane or layer plane. Preferably, the angle of rotation should not be a fraction of 360°, and particularly preferably should have no common divisor with 360° other than one. This avoids a repetition of the orientation of the trajectories in different build material layers.

Claims

1. A computer-aided method for providing control data for an additive manufacturing device (1) for manufacturing a three-dimensional object (2) using the additive manufacturing device, in, The additive manufacturing device is configured such that the object is manufactured by the additive manufacturing device by applying the building material layer by layer and by supplying radiation energy to positions in each layer assigned to a cross section of the object in that layer to solidify the building material in the layer plane (7), The method of providing control data includes: A first step (S1) is to access computer-based model data of a plurality of partial cross-sections of the object to be manufactured, each of the plurality of partial cross-sections comprising a sub-region of the object cross-section and a portion of an edge of the object cross-section, The second step (S2) is to generate a data model of the plurality of partial cross sections, wherein the data model specifies positions of scanning the plurality of partial cross sections along a plurality of trajectories (54) in the slice plane (7) using a plurality of light beams (22). wherein, in at least one of the plurality of partial cross-sections, the order in which the trajectories are scanned is defined such that a starting trajectory is scanned first, wherein at least one point of the starting trajectory is spaced apart from the edge of the object cross-section in the slice plane such that at least one further trajectory is located between the at least one point and the edge, preferably at least two further trajectories are located between the at least one point and the edge, and A third step (S3): providing control data corresponding to the data model generated in the second step (S2) to generate a control data set for manufacturing the object using the additive manufacturing device.

2. The method according to claim 1, wherein In the second step (S2), a data model of at least one partial cross-section in the first building material layer and a data model of at least one partial cross-section in the overlying second building material layer are generated, and a starting trajectory is selected for the partial cross-section in the second building material layer, which starting trajectory overlaps with the starting trajectory of the partial cross-section of the first building material layer at most partially, and preferably does not overlap at all.

3. The method according to claim 2, wherein: The starting trajectory in the partial cross-section of the second building material layer is selected so that its distance from the edge of the object cross-section in the layer plane is different from the distance of the starting trajectory in the partial cross-section of the first building material layer from the edge, wherein the different distances are characterized by a different number of further trajectories being located between the starting trajectory or a point of the starting trajectory and the edge.

4. The method according to claim 2 or 3, wherein: The tracks in the second layer of build material are rotated relative to the tracks in the first layer of build material by angles other than 0°, 90°, and 270°.

5. The method according to claim 4, wherein The tracks in the second layer of build material are rotated relative to the tracks in the first layer of build material by an angle greater than 90° and / or less than 270°.

6. The method according to claim 5, wherein: The angle is greater than 120° or less than 120°, preferably greater than 100° and less than 140°.

7. The method according to claim 1, wherein: The starting trajectory is selected from the plurality of trajectories to be scanned in the partial cross section using a random number generator.

8. The method according to claim 1, wherein: The tracks in the second layer of build material have the same shape and orientation relative to each other as the tracks in the first layer of build material.

9. The method according to claim 1, wherein: The partial cross section is solidified segment by segment, wherein a segment corresponds to a sub-region of the partial cross section, and each segment is solidified by scanning along a plurality of trajectories in the layer plane (7).

10. The method according to claim 9, wherein: The segment is rectangular in shape and the tracks in the segment form an angle with the edge of the segment, the angle ranging from 5° to 175°, preferably from 45° to 135°, particularly preferably from 85° to 95°.

11. The method according to claim 10, wherein: A trajectory located in one of the segments is defined as the starting trajectory, wherein the starting trajectory is defined such that the starting trajectory is scanned in a direction away from the boundary of the segment toward the adjacent adjacent segment, and The first track among the tracks to be scanned in the adjacent adjacent segments is defined such that the first track is scanned starting from a position adjacent to the starting track in a direction away from the boundary.

12. A device for providing control data to an additive manufacturing device (1) for manufacturing a three-dimensional object (2) using the additive manufacturing device, in, The additive manufacturing device is configured such that the object is manufactured by the additive manufacturing device by applying the building material layer by layer and by supplying radiation energy to positions in each layer assigned to a cross section of the object in that layer to solidify the building material in the layer plane (7), Wherein, the device for providing control data includes: an access unit configured to access computer-based model data of a plurality of partial cross-sections of the object to be manufactured, each of the plurality of partial cross-sections comprising a subregion of the object cross-section and a portion of an edge of the object cross-section, a data model generating unit configured to generate a data model of the plurality of partial cross sections, wherein in the data model, positions of scanning the plurality of partial cross sections along a plurality of trajectories (54) in the layer plane (7) using a plurality of light beams (22) are specified, wherein the data model generation unit is configured to define, in at least one of the plurality of partial cross-sections, an order in which the trajectories are scanned, such that a starting trajectory is scanned first, wherein at least one point of the starting trajectory is spaced apart from the edge of the object cross-section in the slice plane, such that at least one further trajectory is located between the at least one point and the edge, preferably at least two further trajectories are located between the at least one point and the edge, and A control data providing unit is configured to provide control data corresponding to the data model generated by the data model generating unit, so as to generate a control data set for manufacturing the object using the additive manufacturing device.

13. A method for controlling an energy input device of an additive manufacturing device (1) for producing a three-dimensional object (2) using the additive manufacturing device, in, The object is manufactured by the additive manufacturing device by applying the building material layer by layer and by supplying radiation energy to the locations in each layer assigned to the object cross section in that layer to solidify the building material in the layer plane (7), The additive manufacturing device comprises an energy input device for supplying radiation energy, wherein the energy input device is configured to solidify the plurality of partial cross sections by scanning the positions of the plurality of partial cross sections of the object to be manufactured along a plurality of tracks (54) in the layer plane (7) using a plurality of light beams (22), each of the plurality of partial cross sections comprising a sub-region of the object cross section and a portion of an edge of the object cross section. Wherein, in the method, for at least one of the multiple partial sections, the order of scanning the trajectories is defined so that a starting trajectory is scanned first, wherein at least one point of the starting trajectory is spaced apart from the edge of the object section in the layer plane, so that at least one further trajectory is located between the at least one point and the edge, preferably at least two further trajectories are located between the at least one point and the edge.

14. An additive manufacturing method for manufacturing a three-dimensional object (2) using an additive manufacturing device, wherein: The method according to claim 13 is performed in the additive manufacturing method.

15. A device for controlling an energy input device of an additive manufacturing device (1) for producing a three-dimensional object (2) using the additive manufacturing device, in, The object is manufactured by the additive manufacturing device by applying the building material layer by layer and by supplying radiation energy to the locations in each layer assigned to the object cross section in that layer to solidify the building material in the layer plane (7), The additive manufacturing device comprises an energy input device for supplying radiation energy, wherein the energy input device is configured to solidify the plurality of partial cross sections by scanning the positions of the plurality of partial cross sections along a plurality of tracks (54) in the layer plane (7) using a plurality of light beams (22), each of the plurality of partial cross sections comprising a sub-region of the object cross section and a portion of an edge of the object cross section, The device comprises a scanning control unit configured to specify, for at least one of the plurality of partial sections, an order in which the trajectories are scanned, such that a starting trajectory is scanned first, wherein at least one point of the starting trajectory is spaced apart from the edge of the object section in the layer plane, such that at least one further trajectory is located between the at least one point and the edge, preferably at least two further trajectories are located between the at least one point and the edge.

16. An additive manufacturing device for manufacturing a three-dimensional object (2) using the additive manufacturing device, wherein: The additive manufacturing apparatus comprises the apparatus according to claim 15.

17. A computer program comprising a series of instructions which, when executed, implement the method according to one of claims 1 to 11 and / or the method according to one of claims 13 or 14.

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