DE102023201157A1 - Exposure strategy within cross sections - Google Patents

Abstract

A method for providing control data for an additive manufacturing device (1) comprises: a first step (S1) of accessing model data of a number of partial cross-sections of the object to be manufactured, each of which comprises a partial area of an object cross-section and a section of the edge of this object cross-section, a second step (S2) of generating a data model of the number of partial cross-sections, wherein in the data model a scanning of the locations of the number of partial cross-sections with a number of rays (22) along a plurality of trajectories (54) in the layer plane (7) is specified, wherein in at least one of the partial cross-sections an order of scanning of the trajectories is defined such that a start trajectory is scanned first, wherein at least one point of the start trajectory is spaced from the edge of the object cross-section such that at least one further trajectory lies between the at least one point and the edge, and a third step (S3) in which control data for the Generation of a tax data record.

Description

The present invention relates to a method and a device for providing control data for an additive manufacturing device, a correspondingly adapted method and a correspondingly adapted device for controlling an energy input device of an additive manufacturing device, a correspondingly adapted additive manufacturing method and a correspondingly adapted additive manufacturing device and a correspondingly adapted computer program.

Additive manufacturing devices and associated methods to which the invention relates are generally characterized in that objects are produced in them by solidifying a shapeless building material (e.g. a metal or plastic powder) layer by layer. Solidification can be brought about, for example, by supplying thermal energy to the building material by irradiating it with electromagnetic radiation or particle radiation (e.g. laser sintering (SLS or DMLS) or laser melting or electron beam melting). For example, in laser sintering or laser melting, a laser beam is moved over those points in a layer of the building material that correspond to the object cross-section of the object to be produced in this layer, so that the building material is solidified at these points. After the building material has been melted or sintered at one point by supplying thermal energy, the building material is no longer in a shapeless state after cooling, but as a solid body. After all the areas of an object cross-section that are to be solidified have been scanned, a new layer of the build-up material is applied and also solidified at the points corresponding to the cross-section of the object in this layer.

The inventors were able to observe undesirable height differences (fluctuations in layer thickness) of the solidified building material at the points of a layer corresponding to the object cross-section, particularly when using metal-containing building materials, after the building material had solidified. Such inhomogeneities make it difficult to produce objects with high precision and impair the manufacturing process. The object of the invention is therefore to provide a method and a device for generating control data for an additive manufacturing device, a correspondingly adapted method and a correspondingly adapted device for controlling an energy input device of an additive manufacturing device, a correspondingly adapted additive manufacturing method and a correspondingly adapted additive manufacturing device and a correspondingly adapted computer program, by means of which objects with improved detail resolution can be obtained through a more reliable additive manufacturing process.

The object is achieved by a method for providing control data according to claim 1, a corresponding device according to claim 12, a correspondingly adapted method for controlling an energy input device according to claim 13, a correspondingly adapted additive manufacturing method according to claim 14, a correspondingly adapted device for controlling an energy input device according to claim 15, a correspondingly adapted additive manufacturing device according to claim 16 and a correspondingly adapted computer program according to claim 17.

Further developments of the invention are claimed in the dependent claims. In particular, a device according to the invention can also be further developed by features of the methods according to the invention set out below or in the dependent claims, and vice versa. Furthermore, the features described in connection with a device according to the invention can also be used to further develop another device according to the invention, even if this is not explicitly stated.

• einen ersten Schritt (S1) des Zugriffs auf computerbasierte Modelldaten einer Anzahl von Teilquerschnitten des herzustellenden Objekts, von denen jeder eine Teilfläche eines Objektquerschnitts sowie einen Abschnitt des Rands dieses Objektquerschnitts umfasst,
• einen zweiten Schritt (S2) des Erzeugens eines Datenmodells der Anzahl von Teilquerschnitten, wobei in dem Datenmodell ein Abtasten der Stellen der Anzahl von Teilquerschnitten mit einer Anzahl von Strahlen entlang einer Mehrzahl von Trajektorien in der Schichtebene spezifiziert ist,
  • wobei in mindestens einem der Anzahl von Teilquerschnitten eine Reihenfolge der Abtastung der Trajektorien so festgelegt ist, dass als Erstes eine Starttrajektorie abgetastet wird, wobei zumindest ein Punkt der Starttrajektorie vom Rand des Objektquerschnitts in der Schichtebene dergestalt beabstandet ist, dass mindestens eine weitere Trajektorie zwischen dem zumindest einen Punkt und dem Rand liegt, bevorzugt mindestens zwei weitere Trajektorien zwischen dem zumindest einen Punkt und dem Rand liegen, und
• einen dritten Schritt (S3), in dem Steuerdaten entsprechend dem im zweiten Schritt (S2) erzeugten Datenmodell für die Generierung eines Steuerdatensatzes für die Herstellung des Objekts mittels der additiven Herstellvorrichtung bereitgestellt werden.

A computer-aided method according to the invention for providing control data for an additive manufacturing device for producing a three-dimensional object by means of the same,
wherein the additive manufacturing device is designed such that objects are manufactured by means of the additive manufacturing device by applying a building material layer upon layer and solidifying the building material in a layer plane by supplying radiant energy to those locations in each layer which are associated with an object cross-section in that layer, comprises:

• a first step (S1) of accessing computer-based model data of a number of partial cross-sections of the object to be manufactured, each of which comprises a partial area of an object cross-section and a portion of the edge of this object cross-section,
• a second step (S2) of generating a data model of the number of partial cross-sections, wherein the data model specifies scanning of the locations of the number of partial cross-sections with a number of rays along a plurality of trajectories in the layer plane,
  • wherein in at least one of the number of partial cross-sections, an order of scanning of the trajectories is determined such that a start trajectory is scanned first, wherein at least one point of the start trajectory is spaced from the edge of the object cross-section in the layer plane such that at least one further trajectory lies between the at least one point and the edge, preferably at least two further trajectories lie between the at least one point and the edge, and
• a third step (S3) in which control data corresponding to the data model generated in the second step (S2) are provided for the generation of a control data set for the production of the object by means of the additive manufacturing device.

In particular, the method can be carried out entirely by a computer which carries out all process steps independently without the intervention of an operator.

Additive manufacturing devices and methods to which the present invention relates are in particular those in which energy is selectively supplied to a layer of a formless building material as electromagnetic radiation or particle radiation. The working plane (also referred to as the building plane) is a plane in which the top side of the layer to which the energy is supplied lies and is also referred to here as the layer plane. The radiation energy can be generated, for example, by a laser or an electron beam source, although a plurality of radiation sources and/or beams can also be used. The radiation supplied to the building material heats it and thereby causes a sintering or melting process. In particular, the present invention relates to laser sintering, laser melting and electron beam melting devices and the associated methods. Although the invention can be used both in connection with plastic-based building material and in connection with metal-based building material, an application of the invention in connection with additive manufacturing methods and devices in which a metallic or at least metal-containing building material is used, for example a metal powder or metal alloy powder, is of particular advantage. In particular, the invention can also be used in connection with a combination of a metal-based building material and a plastic-based building material, wherein a combination consists of a mixture between a metal-based and a plastic-based building material, wherein optionally additionally further components can also be included. For example, a building material can be powdery and in particular the powder grains can consist of a metal-containing core and a plastic-containing coating (or vice versa).

It should be noted at this point that not only one object but also several objects can be produced simultaneously using an additive manufacturing device according to the invention. When the present application refers to the production of an object, it is understood that the respective description is equally applicable to additive manufacturing methods and devices in which several objects are produced simultaneously.

The term "beam" is not intended to express that the diameter of the beam must be very small. Rather, the beam impact area on the build material (in the build plane or layer plane) can also have a larger diameter, especially if the radiation hits the build material at an angle or if a larger beam impact area is deliberately created when it hits the build material by beam shaping.

A trajectory of a beam specified in a data model specifies a track of a beam in the construction plane when the beam is directed at the construction material. The data model thus specifies at which locations (places to be solidified) a beam should hit the layer plane and in which chronological order the locations in the layer plane should be scanned. In the context of the invention, a trajectory is defined as a path that has a predefined directional course that can be described by a single, concrete 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 direction), this is a new trajectory that can be distinguished from the previously mathematically described trajectory by the different function. Along the course of the trajectory, the beam can be directed at the construction material, but there can also be locations along the trajectory where the beam is switched off. or paused. In other words, the radiation source does not necessarily have to be permanently activated when a scanner moves along the trajectory.

When scanning the areas of a layer to be solidified, a distinction is sometimes made between an inner area and an edge area (often an edge line whose width roughly corresponds to the diameter of the beam impact area on the build material in the build plane perpendicular to the direction of movement of the beam) of an object cross-section. The inner area is solidified by moving the beam along trajectories that are usually essentially parallel to one another. The area is hatched, so to speak, which is why the individual trajectories are also referred to as "hatch lines". In particular, in the present application, the term "trajectory" is often used synonymously with "hatch line" or scan line, even if strictly speaking a trajectory refers to a line specified in the control data (of zero width) and a "hatch line" or scan line refers to a track in the build plane (with a width other than zero, which roughly corresponds to the diameter of the beam impact surface on the build material in the build plane perpendicular to the direction of movement of the beam). In order to take into account the non-zero widths of the melt tracks in the build plane, the trajectories or hatch lines are spaced apart from one another in the data model, so that a uniform, gap-free energy input into the build material is possible when scanning the same. Within the scope of the invention, it is preferred that the hatch lines are designed as straight lines.

The edge region (also referred to as the contour region) of an object cross-section is generally solidified by moving a beam along the course of the edge region. The trajectories to which the present application refers, on the other hand, are lines traversed when scanning an inner region of an object cross-section. A scanning of an edge region of the object cross-section can take place either before or after scanning the inner region or, particularly if a different beam than that used for scanning the inner region is used for scanning the edge region, it can take place with a temporal overlap with the scanning of the inner region.

The computer-based model data, which is accessed in the first step, contains a geometric description of the (partial cross-section of the) object, i.e. in particular a three-dimensional CAD model, although there are also other possibilities for geometric description, e.g. a description using a set of parameters and a design specification. In this context, it is only important that the model data describe the geometric shape of at least one partial cross-section of an object to be manufactured, to which a layer of the construction material, preferably exactly one layer, is assigned.

Even if the second step refers to the generation of a data model of a partial cross-section, it is understood that a data model can also be generated that relates to a plurality of partial cross-sections, i.e. for at least one, preferably a plurality, particularly preferably all of these partial cross-sections, specifies an inventive scanning of locations of the partial cross-section with a number of rays along a plurality of trajectories in the layer plane. The prerequisite for this is that the corresponding computer-based model data of these partial cross-sections is accessed in the first step. The invention includes data models in which the number of partial cross-sections is assigned to the same building material layer. In particular, however, data models can also be generated that relate to a plurality of partial cross-sections that are assigned to different building material layers. If necessary, a data model of the entire object can also be generated.

A partial cross-section of an object is defined here as a partial area (partial surface) of a cross-section of an object to which a layer of the building material is assigned during additive manufacturing. This partial area is additionally characterized in that it comprises a section of the edge of an object cross-section, i.e. borders on areas in the layer plane outside the object cross-section that are not to be solidified. In a preferred embodiment of the invention, a partial cross-section according to the invention is at least predominantly separated from the other areas of the entire object cross-section by building material that is not to be solidified. This means that the edge of an area of a building material layer assigned to the partial cross-section borders on building material that is not to be solidified with at least 50%, preferably with at least 75%, even more preferably with at least 95% of its length, particularly preferably with 100% of its length. If a partial cross-section does not border with its entire edge on areas in the layer plane that are not to be consolidated, the shape and position of the partial cross-sections in the layer plane can either be specified by an operator of the process, for example by modifying the computer-based model data, or can be defined fully automatically. For example, by automatically defining the shape and position of the partial cross-sections, a partial area of an object cross-section that differs from the other areas of the entire object cross-section by at least one geometric property (e.g. 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, a partial cross-section can also include the entire cross-section of an object to be produced, but only if the entire cross-section does not break down into separate partial areas (partial areas) (i.e. if it is path-connected in a mathematical sense).

It should also be noted that a partial cross-section according to the invention can only be a surface with a minimum extent in each direction in the layer plane. The minimum extent is preferably at least three times, more preferably at least five times the distance between adjacent trajectories that are traversed to solidify the partial cross-section.

Furthermore, it should be noted that the invention is advantageous regardless of the manner in which partial cross-sections are defined within a (path-connected) object cross-section.

A start trajectory is defined here as the trajectory that is traversed first in time when scanning a partial cross-section.

A distance of the starting trajectory from the edge of the partial cross-section in the layer plane is defined in the present case such that at least one further trajectory lies between the starting trajectory and the edge at at least one point of the starting trajectory, preferably at least two further trajectories lie between the starting trajectory and the edge. The distance of a point of the starting trajectory from the edge is further preferably 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 of the starting trajectory that specifies the point in the construction plane to which the beam is first directed when scanning the starting trajectory. The starting point then corresponds to a two-dimensional area in the construction plane or layer plane that is essentially as large as the impact area of the beam on the construction plane.

Preferably, at least 25% of the points of the start trajectory to which the start point preferably belongs, more preferably at least 50% of the points of the start trajectory, even more preferably at least 75% of the points of the start trajectory to which the start point preferably belongs, even more preferably at all points of the start trajectory, there is at least one further trajectory between the start trajectory and the edge, preferably at least two further trajectories.

The control data set can be viewed as the totality of all control data specified for controlling the manufacturing process in an additive manufacturing device. The control data relating to an individual layer is usually referred to as a layer data set. In the present application, it is assumed in particular that a layer data set contains a data model of locations of an object cross-section or partial object cross-section to be solidified in a layer by means of one or more beams during the manufacturing process. In addition, further information regarding the production of the object cross-section can be included, in particular the temporal sequence in which locations corresponding to an object cross-section or partial object cross-section are to be solidified by specifying scan lines or trajectories along which the beam is to be moved, a temporal sequence of scanning a plurality of scan lines or trajectories or, for example, the layer thickness or irradiation parameter values, such as the diameter or travel speed of a beam striking the build-up material, etc.

The provision of control data according to the invention allows the achievement of more uniform thicknesses of the solidified building material layers in a layer-by-layer additive manufacturing process. On the one hand, this allows the production of objects with more precise dimensions perpendicular to the layer planes (usually referred to as the z-direction), and on the other hand, this avoids impairment of the layer application due to elevations protruding upwards from an already solidified layer, which could potentially collide with a coating element.

• Dort wo ein Strahl auf das Aufbaumaterial auftrifft, bildet sich ein Schmelzbad aus Bei der Bewegung des Strahls entlang einer Trajektorie bewegt sich dieses Schmelzbad im Aufbaumaterial, so dass eine Schmelzspur generiert wird, die nach Erstarren eine Verfestigungsbahn bestehend aus verfestigtem Aufbaumaterial darstellt. Aufgrund der Oberflächenspannung, die sich an der Oberfläche des Schmelzbads bildet, wird unverfestigtes Aufbaumaterial aus dem Bereich in der Nähe des Schmelzbads ins Schmelzbad selbst gezogen. Außerdem wird verschmolzenes (noch nicht erstarrtes) Aufbaumaterial von der Schmelzspur in die Richtung des ersten Auftreffpunkts des Strahls gezogen, solange dort ein Schmelzbad weiter entsteht. Beim ersten Auftreffen des Strahls auf eine aufgetragene Aufbaumaterialschicht steht dem Schmelzbad mehr Aufbaumaterial zur Verfügung, sodass der Aufbaumaterialtransport in die Auftreffposition bzw. in die erste Schmelzspur (wenn der Strahl entlang einer Trajektorie in der Bauebene bewegt wird) größer als der Aufbaumaterialtransport in die anderen Positionen ist. Dies führt zu einer Vermehrung des aufgeschmolzenen Materials und daraus resultierend zu einer Verdickung insbesondere der ersten Verfestigungsbahn in z-Richtung (im Folgenden werden auch die Begriffe „Aufbaumaterialansammlung“ und „Überhöhung“ verwendet, um entsprechend die Vermehrung des aufgeschmolzenen Materials und die Verdickung einer Verfestigungsbahn in z-Richtung zu beschreiben). Die nachfolgenden Verfestigungsbahnen sind in geringerem Maße verdickt (erhöht), da seitlich der entsprechenden Schmelzspuren weniger unverfestigtes Aufbaumaterial vorhanden ist. In den nachfolgenden Verfestigungsbahnen (bzw. in Positionen, die vom ersten Auftreffpunkt des Strahls bzw. von der ersten Verfestigungsbahn entfernt sind) ergibt sich also ein Aufbaumaterialmangel, weil Aufbaumaterial von diesen Verfestigungsbahnen (Positionen) zum ersten Auftreffpunkt des Strahls bzw. in die erste Verfestigungsbahn transportiert wurde. Wenn in den folgenden Schichten die Starttrajektorie, die wiederum vom Rand des zugehörigen Objekt(teil)querschnitts beabstandet ist, an anderer Stelle in der Bauebene liegt als in der/den vorangegangenen Schicht/en, dann kann darüberhinaus eine Überhöhung in vorangegangenen Schichten effizienter kompensiert werden.

The inventors explain the improvements achieved as follows:

• Where a beam hits the build-up material, a melt pool forms. When the beam moves along a trajectory, this melt pool moves in the build-up material, so that a melt track is generated, which after solidification represents a solidification path consisting of solidified build-up material. Due to the surface tension that forms on the surface of the melt pool, forms, unsolidified buildup material is drawn from the area near the melt pool into the melt pool itself. In addition, molten (not yet solidified) buildup material is drawn from the melt track in the direction of the first impact point of the jet as long as a melt pool continues to form there. When the jet first impacts an applied buildup material layer, more buildup material is available to the melt pool, so that the buildup material transport into the impact position or into the first melt track (if the jet is moved along a trajectory in the build plane) is greater than the buildup material transport into the other positions. This leads to an increase in the molten material and, as a result, to a thickening of the first solidification path in the z direction in particular (the terms "buildup material accumulation" and "superelevation" are also used below to describe the increase in molten material and the thickening of a solidification path in the z direction respectively). The subsequent solidification paths are thickened (raised) to a lesser extent because there is less unsolidified build-up material to the side of the corresponding melting tracks. In the subsequent solidification paths (or in positions that are away from the first point of impact of the beam or from the first solidification path), there is therefore a lack of build-up material because build-up material was transported from these solidification paths (positions) to the first point of impact of the beam or into the first solidification path. If in the following layers the starting trajectory, which in turn is spaced from the edge of the associated object (partial) cross-section, is located at a different point in the build plane than in the previous layer(s), then an over-raised area in previous layers can be compensated more efficiently.

Preferably, in the second step (S2), a data model of at least one partial cross-section in a first building material layer and at least one partial cross-section in an overlying second building material layer is generated and a starting trajectory is selected for the partial cross-section in the second building material layer, which at most partially, preferably not at all, overlaps with the starting trajectory for the partial cross-section of the first building material layer.

An overlap can occur if the two starting trajectories intersect in the build plane. Alternatively, an overlap can occur if the two starting trajectories are at least partially congruent in the build plane or parallel to each other and slightly offset from each other in the build plane. An overlap can also occur if the starting trajectories are slightly offset in the build plane, since it must be taken into account that the trajectories correspond to tracks in the build material with a width other than zero. If it is assumed that the distance between the trajectories specified for a build material layer corresponds to the track width in the build material, then an overlap already exists 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 a constant value is usually specified for the distance between the trajectories within a build material layer, the average distance usually corresponds to the specified constant distance.

If the starting trajectory in the second building material layer covers the starting trajectory in the first building material layer without a lateral offset, there should preferably be an overlap of a maximum of half the length of the starting trajectory in the first building material layer, more preferably an overlap of a maximum of 1/10, particularly preferably an overlap of a maximum of 1/100 of the length of the starting trajectory in the first building material layer. Since the starting trajectories each correspond to a track with a width corresponding to the trajectory spacing in the building material layer, one can also say in short that the values given above for the maximum covered length of the starting trajectory in the first building material layer correspond to the values for the maximum covered area of the starting trajectory in the first building material layer. If there is a lateral offset of the two starting trajectories, the covered area of the starting trajectory in the first building material layer can be calculated accordingly using the following equation: $$\ddot{\text{u}}\text{covered fl}\ddot{\text{a}}\text{che}=\ddot{\text{u}}\text{covered L}\ddot{\text{a}}\text{nge}\times \left(\text{Trajectory distance}-\text{Offset}\right)$$

It was assumed that the offset has a value between zero and the trajectory distance. This means that even if there is an offset of the starting trajectories and generally for any course of the starting trajectories, it can be said that preferably there should be an overlap of a maximum of half the area of the starting trajectory in the first building material layer, more preferably an overlap of a maximum of 1/10, particularly preferably an overlap of a maximum of 1/100 of the area of the starting trajectory in the first building material layer.

Preferably, the starting point of the starting trajectory in the second building material layer is laterally offset from the starting point of the starting trajectory in the first building material layer in the building plane by an amount that is greater than the average distance between the trajectories in the first building material layer, preferably greater than twice the average distance between the trajectories in the first building material layer, even more preferably greater than three times the average distance between the trajectories in the first building material layer. As a rule, a distance between the trajectories is specified for a building material layer, so that the average distance between the trajectories simply corresponds to the distance specified for the building material layer.

This procedure creates a data model of a plurality of partial cross-sections that are assigned to different building material layers.

Since there is an elevation in the solidified build-up material layer in the area of the starting trajectory, the elevations can add up at the points in the build plane where the areas of the starting trajectories in different build-up material layers lie on top of each other - just a few layers are enough here. As a result, the sum of the elevations in an upper layer could be so large that when another build-up material layer is applied, a coating element used for this purpose could collide with an elevated point. This would lead to the construction process being aborted and possibly even damage to the coating element.

By not completely overlapping the starting trajectory in a second build material layer with the starting trajectory in a first layer, an increase in the elevation resulting from the first build material layer can be prevented or reduced in the second build material layer. By compensating for the elevations, for example in a first and a second layer, an impairment of the manufacturing process or an interruption of the same can also be avoided.

It is also preferred that the starting trajectories in more than two consecutive layers of building material overlap at most partially, and even more preferably not at all. This leads to an even more efficient avoidance of large overshoots.

Further preferably, the starting trajectory in the partial cross-section of the second building material layer is selected such that it has a different distance from the edge of the object cross-section in the layer plane than the starting trajectory in the partial cross-section of the first building material layer, wherein the other distance is characterized by the fact that a different number of further trajectories lie between the starting trajectory or a point thereof and the edge.

Particularly when the position and orientation of the partial cross-sections in the first and second build material layers are very similar to one another, this procedure can ensure that a starting trajectory in a first build material layer and a starting trajectory in a second build material layer are offset in the build plane. This minimizes or completely prevents an overlap of the starting trajectories. Preferably, the start trajectories are carried out in the manner just described in more than two consecutive build material layers, whereby a distance with respect to another build material layer following the first build material layer can also be changed.

Further preferably, the trajectories in the second building material layer are rotated relative to the trajectories in the first building material layer by an angle that is different from 0°, 90° and 270°.

The preferred angles serve to efficiently reduce an increase in the superelevations by changing a build material accumulation and a build material deficiency in a build material layer located above the first build material layer compared to the first build material layer (or another build material layer following the first build material layer) by rotating the trajectories.

The preferred angles are particularly applicable in the case where the first and second building material layers lie directly on top of one another. If possible, a rotation angle can also be selected which ensures that the starting trajectory in the second building material layer does not overlap the starting trajectory in the first building material layer. In general, a rotation angle should preferably be selected which, if a rotation by this angle takes place from layer to layer, only overlaps the starting trajectory in an overlying building material layer with the starting trajectory of the first building material layer after as many layers as possible.

It should be noted that the above angle specifications apply regardless of the direction in which the rotation takes place, although preferably the direction of rotation is always the same.

Further preferably, the trajectories in the second building material layer are rotated relative to the trajectories in the first building material layer by an angle that is greater than 90° and/or less than 270°.

Even more preferably, the angle is greater than 120° or less than 120°, preferably greater than 100° and less than 140°.

The value of 120° is excluded because a rotation of 120° from layer to layer in the layer after the second building material layer would again have the same orientation of the trajectories in the building plane as in the first building material layer, which is usually undesirable.

For the preferred angle range, particularly homogeneous thicknesses of the solidified layer areas could be achieved. In particular, within this angle range it is possible to ensure that the trajectories in the successive build-up material layers are as heterogeneous as possible, i.e. in as many different directions as possible. By ensuring sufficient heterogeneity of the trajectories in the successive build-up material layers, it can often be ensured that the starting trajectory in a subsequent build-up material layer only overlaps with the trajectory of a previous build-up material layer after as many layers as possible. This makes it possible to efficiently compensate for the elevations in this angle range by rotating the trajectories so that a build-up material accumulation and a build-up material deficiency occur in the build plane at places other than those in the first build-up material layer.

Particularly preferred values for the angle are 105°, 115°, 125°, 130°, 135° or 140°.

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

It is often the case that the shape of a (partial) cross-section and its position in the construction plane change only slightly (or in some cases not at all) from one layer of building material to the next. In these cases in particular, the addition of elevations caused by superimposed areas of the starting trajectories can be avoided by modifying the distance between the starting trajectory and the edge in the individual layers. This is particularly true for cases in which the trajectories in the second layer of building material run essentially parallel to the trajectories in the first layer of building material. The use of the random principle is intended to ensure that there is no overlap of starting trajectories of superimposed building material layers or that there is only a small number of overlaps of starting trajectories of superimposed building material layers.

Preferably, the trajectories in a second building material layer have the same shape and orientation to one another as the trajectories in a first building material layer.

In this case, it is easier to choose a starting trajectory in the second build material layer such that this starting trajectory has as little overlap as possible with the starting trajectory in the first build material layer.

Preferably, individual or all sections of at least two trajectories, particularly preferably of all trajectories, are parallel to one another in a partial cross-section. The parallelism of the trajectories in a partial cross-section, in particular in each partial cross-section of the number of partial cross-sections, facilitates the selection of the starting trajectory, since in this case it is easy to check whether there are further trajectories between the intended starting trajectory and the edge of the object cross-section. It should be emphasized that parallel trajectories or sections thereof do not necessarily have to be straight. Rather, parallelism can also be present in curved curves, in particular in closed line courses of the trajectories.

Preferably, a partial cross-section is solidified segment by segment, wherein a segment corresponds to a partial area of the partial cross-section and each segment is solidified by scanning along a plurality of trajectories in the layer plane.

A segment is a partial area of a partial cross-section, so that in a segment-by-segment consolidation, the area of a building material layer corresponding to the partial cross-section is solidified partial area by partial area. The segments preferably have the same shape and orientation in the layer plane or construction plane. The segments particularly preferably have a rectangular shape, in particular a square shape. Further preferably, the shape and orientation in the construction plane of the trajectories is the same in all segments, and particularly preferably also the direction in which the trajectories in a segment are scanned one after the other (the trajectory sequence direction), so that the position of the trajectory to be scanned first relative to the area of the segment is also the same for all segments.

When solidifying the area of a build-up material layer corresponding to the partial cross-section in segments, the distance of the starting trajectory from the edge of the object cross-section can be achieved by appropriately selecting the segment to be solidified first in the partial cross-section. This applies in particular to the case in which the position of the trajectory to be scanned first relative to the area of the segment is the same in all segments and the shape and orientation of the segments in the build plane is the same.

Preferably, the trajectories within a segment run parallel to each other.

Further preferably, the segments have a rectangular shape and the trajectories in the segments enclose an angle between 5° and 175°, preferably between 45° and 135°, particularly preferably between 85° and 95°, with an edge of the segment.

Preferably, this procedure uses straight-line trajectories, in particular trajectories that are parallel to one another, in the individual segments. The angles mentioned refer to an angle that a start section or end section of the trajectory - the start and end are determined by the direction in which the trajectory is traversed - encloses with an edge of the segment. Preferably, the angle is essentially 90°, in particular exactly 90°.

Even more preferably, a trajectory lying in one of the segments is defined as the starting trajectory,
wherein the starting trajectory is set to be scanned in a direction pointing away from a boundary of the segment to an adjacent neighboring segment, and
wherein the first of the trajectories to be scanned in the adjacent neighboring segment is determined to be scanned starting at a location adjacent to the starting trajectory in a direction pointing away from the boundary.

The region in the plane in which the two segments border one another is considered to be the boundary between two segments. This is preferably a boundary line or edge line. The reason why the boundary can also be viewed as a region is that there can be embodiments in which the trajectories of one segment extend a little way into the other segment or start or end at a certain distance from the other segment. However, the resulting "overlap" or the remaining distance to the other segment is usually less than the width of the track corresponding to the trajectories in the building material layer, in other words less than the distance between the trajectories adjacent to one another in a segment.

In this context, a location adjacent to the starting trajectory is in particular a location in the neighboring segment whose distance to the starting point of the starting trajectory is smaller than the width of the track corresponding to the trajectories in the building material layer or smaller than the distance between neighboring trajectories in the segment in which the starting trajectory lies.

If a trajectory is scanned in a direction that points away from the boundary, then this is immediately obvious for trajectories that are perpendicular to the boundary. If the trajectories enclose an angle other than 90° with the boundary, then when scanning away from the boundary, there is at least one directional component of the movement that points away from the boundary.

The inventors explain the advantage of this procedure by the fact that scanning the starting trajectory in the area of the neighboring segment that lies next to the starting trajectory results in a lack of build-up material. If this area is scanned first in the neighboring segment, then this lack of build-up material is compensated for by the fact that when this area is solidified, build-up material that is adjacent to this area and has not yet solidified is used in addition to the build-up material in this area. already existing unsolidified build-up material is solidified or adjacent already solidified build-up material is melted/melted again and drawn into this area.

It is also preferable for all trajectories to be scanned in the same direction in both the segment in which the starting trajectory lies and in the adjacent neighboring segment. This means that the starting points of all trajectories are then preferably located at or near the border between the two segments. This approach can take into account the fact that an elevation tends to occur at the beginning of a trajectory.

• eine Zugriffseinheit, die ausgelegt ist, auf computerbasierte Modelldaten einer Anzahl von Teilquerschnitten des herzustellenden Objekts zuzugreifen, von denen jeder eine Teilfläche eines Objektquerschnitts sowie einen Abschnitt des Rands dieses Objektquerschnitts umfasst,
• eine Datenmodell-Erzeugungseinheit, die ausgelegt ist, ein Datenmodell der Anzahl von Teilquerschnitten zu erzeugen, wobei in dem Datenmodell ein Abtasten der Stellen der Anzahl von Teilquerschnitten mit einer Anzahl von Strahlen entlang einer Mehrzahl von Trajektorien in der Schichtebene spezifiziert ist,
  • wobei die Datenmodell-Erzeugungseinheit ausgelegt ist, in mindestens einem der Anzahl von Teilquerschnitten eine Reihenfolge der Abtastung der Trajektorien so festzulegen, dass als Erstes eine Starttrajektorie abgetastet wird, wobei zumindest ein Punkt der Starttrajektorie vom Rand des Objektquerschnitts in der Schichtebene dergestalt beabstandet ist, dass mindestens eine weitere Trajektorie zwischen dem zumindest einen Punkt und dem Rand liegt, bevorzugt mindestens zwei weitere Trajektorien zwischen dem zumindest einen Punkt und dem Rand liegen, und
• eine Steuerdaten-Bereitstellungseinheit, die ausgelegt ist, Steuerdaten entsprechend einem von der Datenmodell-Erzeugungseinheit erzeugten Datenmodell für die Generierung eines Steuerdatensatzes für die Herstellung des Objekts mittels der additiven Herstellvorrichtung bereitzustellen.

A device according to the invention for providing control data for an additive manufacturing device for producing a three-dimensional object by means of the same,
wherein the additive manufacturing device is designed such that objects are manufactured by means of the additive manufacturing device by applying a building material layer upon layer and solidifying the building material in a layer plane by supplying radiant energy to those locations in each layer which are associated with the cross-section of the object in that layer, comprises:

• an access unit designed to access computer-based model data of a number of partial cross-sections of the object to be produced, each of which comprises a partial area of an object cross-section and a portion of the edge of this object cross-section,
• a data model generation unit configured to generate a data model of the number of partial cross-sections, wherein the data model specifies scanning of the locations of the number of partial cross-sections with a number of rays along a plurality of trajectories in the layer plane,
  • wherein the data model generation unit is designed to determine an order of scanning of the trajectories in at least one of the number of partial cross-sections such that a start trajectory is scanned first, wherein at least one point of the start trajectory is spaced from the edge of the object cross-section in the layer plane such that at least one further trajectory lies between the at least one point and the edge, preferably at least two further trajectories lie between the at least one point and the edge, and
• a control data providing unit configured to provide control data corresponding to a data model generated by the data model generating unit for generating a control data set for manufacturing the object by means of the additive manufacturing device.

The provision of the data model generated by the data model generation unit for the generation of a control data set can be done by the control data provision unit itself by integrating the generated data model into a control data set for the additive manufacturing device. However, provision also includes forwarding the data model to a data processing device, which integrates the data model into a control data set, or forwarding it directly to an additive manufacturing device. In particular, it is possible to dynamically provide data models for object cross-sections that are still to be manufactured in the additive manufacturing device during a manufacturing process.

In a method according to the invention for controlling an energy input device of an additive manufacturing device for producing a three-dimensional object by means of the same,
wherein the object is manufactured by means of the additive manufacturing device by applying a building material layer upon layer and solidifying the building material in a layer plane by supplying radiant energy to those locations in each layer which are associated with the cross-section of the object in that layer,
wherein the additive manufacturing device for supplying radiation energy has an energy input device which is designed to solidify a number of partial cross-sections of the object to be produced, each of which comprises a partial area of an object cross-section and a portion of the edge of this object cross-section, by scanning the locations of the number of partial cross-sections with a number of beams along a plurality of trajectories in the layer plane,
For at least one of the number of partial cross-sections, an order of scanning of the trajectories is determined such that a start trajectory is scanned first, wherein at least one point of the start trajectory is spaced from the edge of the object cross-section in the layer plane such that at least one further trajectory lies between the at least one point and the edge, preferably at least two further trajectories lie between the at least one point and the edge.

To scan the construction material along trajectories, the energy input device can in particular have a number of beam deflection devices (e.g. galvanometer scanners) by means of which light from a radiation source (e.g. a laser) is directed to the desired locations in the construction plane, the speed of movement of the beam(s) over the construction plane also being controlled via the beam deflection devices. The method for controlling the energy input device can in particular be implemented by processing a control data set that was generated using the control data provided by a method according to the invention for providing control data.

In an additive manufacturing method according to the invention for producing a three-dimensional object by means of an additive manufacturing device, a method according to the invention for controlling an energy input device of an additive manufacturing device is carried out.

Preferably, these are manufacturing processes in which a metal-based building material is used, i.e. a building material in which the metal content exceeds 50 percent by weight, e.g. a metal powder or metal alloy powder such as steel powder or powder containing chromium, titanium, tungsten, cobalt, nickel, copper or aluminum, whereby the list of the elements mentioned is not intended to be exhaustive. In particular, however, a combination of a metal-based building material and a plastic-based building material can also be used, whereby the combination consists of a mixture between a metal-based and a plastic-based building material, whereby additional components can optionally also be included. For example, a building material can be in powder form and in particular the powder grains can consist of a metal-containing core and a plastic-containing coating (or vice versa). The additive manufacturing process is preferably a laser sintering process or a laser melting process.

A device according to the invention for controlling an energy input device of an additive manufacturing device for producing a three-dimensional object by means of the same,
wherein the objects are manufactured by means of the additive manufacturing device by applying a building material layer upon layer and solidifying the building material in a layer plane by supplying radiant energy to those locations in each layer which are associated with the cross-section of the object in that layer,
wherein the additive manufacturing device for supplying radiation energy has an energy input device which is designed to solidify a number of partial cross-sections, each of which comprises a partial area of an object cross-section and a portion of the edge of this object cross-section, by scanning the locations of the number of partial cross-sections with a number of beams along a plurality of trajectories in the layer plane,
has a scanning control unit which is designed to specify a sequence of scanning of the trajectories for at least one of the number of partial cross-sections such that a start trajectory is scanned first, wherein at least one point of the start trajectory is spaced from the edge of the object cross-section in the layer plane such that at least one further trajectory lies between the at least one point and the edge, preferably at least two further trajectories lie between the at least one point and the edge.

The control device of an energy input device is able to implement the method described above for controlling an energy input device. The individual components of the device, in particular the scanning control unit, or the entire control device can be implemented using software alone, hardware alone, or a mixture of hardware and software. Interfaces do not necessarily have to be designed as hardware components, but can also be implemented as software modules. Interfaces can also consist of both hardware and software components, for example in the form of a standard hardware interface that is specially configured by software for the specific application. In addition, several interfaces can also be combined in a common interface, for example an input-output interface.

In particular, the control device can be a unit within a control device that controls a manufacturing process in an additive manufacturing device. Nevertheless, it should be emphasized that the control device can also be present outside the control device in the same way and can exchange signals with the additive manufacturing device, in particular with the energy input device, via a network. In particular, if the control device is implemented solely by means of software, the control device can be in the form of a computer program. Preferably then such a computer program for a manufacturing process is executed by the additive manufacturing device in its control device.

An additive manufacturing device according to the invention for producing a three-dimensional object by means of the same has a device according to the invention for controlling an energy input device of an additive manufacturing device.

The additive manufacturing device is preferably designed for producing objects from a metal-based construction material in which the metal content exceeds 50 percent by weight, e.g. a metal powder or metal alloy powder such as steel powder or powder containing chromium, titanium, tungsten, cobalt, nickel, copper or aluminum, whereby the list of the elements mentioned is not intended to be exhaustive. In particular, the additive manufacturing device can be designed for producing objects from a combination of a metal-based construction material and a plastic-based construction material, whereby the combination consists of a mixture between a metal-based and a plastic-based construction material, whereby additional components can optionally also be included. For example, a construction material can be in powder form and in particular the powder grains can consist of a metal-containing core and a plastic-containing coating (or vice versa). The additive manufacturing device is preferably a laser sintering device or laser melting device.

A computer program according to the invention comprises a sequence of commands which, when executed, implement a computer-aided method according to the invention for providing control data for an additive manufacturing device and/or a method according to the invention for controlling an energy input device of an additive manufacturing device or an additive manufacturing method according to the invention for producing a three-dimensional object by means of an additive manufacturing device.

A computer program by which a method according to the invention for providing control data is implemented can be executed on a computer or data processor that is completely independent of the additive manufacturing device, in particular cannot exchange data with it. Execution of the computer program's commands by a data processor integrated into the additive manufacturing device or interacting with it is of course advantageous. The implementation of the method according to the invention for providing control data and the associated device by means of software enables easy installation on different IT systems at different locations (for example at the creator of the design of the object or at the operator of the additive manufacturing device).

• 1 zeigt eine schematische, teilweise im Schnitt dargestellte Ansicht einer beispielhaften Vorrichtung zum additiven Herstellen eines dreidimensionalen Objekts gemäß der Erfindung.
• 2a bis 2c dienen der Erläuterung des in der Anmeldung verwendeten Begriffs "Teilquerschnitt.
• 3 zeigt schematisch ein Beispiel für ein erfindungsgemäßes Vorgehen bei der Festlegung der Starttrajektorie.
• 4 zeigt schematisch ein weiteres Beispiel für ein erfindungsgemäßes Vorgehen bei der Festlegung der Starttrajektorie.
• 5a bis 5c dienen der Erläuterung der Möglichkeiten der Definition eines Abstands zwischen der Starttrajektorie und dem Rand eines Objektquerschnitts.
• 6a bis 6c dienen der Veranschaulichung des Vorgehens bei der Festlegung der Starttrajektorien in mehreren Schichten.
• 7 zeigt schematisch den Ablauf eines erfindungsgemäßen Verfahrens zur Bereitstellung von Steuerdaten.
• 8 zeigt schematisch den Aufbau einer erfindungsgemäßen Vorrichtung zur Bereitstellung von Steuerdaten.
• 9a und 9b zeigen ein weiteres Beispiel für das Vorgehen bei der Festlegung der Starttrajektorien in mehreren Schichten.
• 10a und 10b zeigen Varianten des Vorgehens gemäß 4.

A computer program by which a method according to the invention for controlling an energy input device or an additive manufacturing method according to the invention is implemented is preferably executed on a data processor that is integrated into the additive manufacturing device or interacts with it. The term "interaction" mentioned several times above is intended to mean that the data processor can exchange data with the additive manufacturing device, e.g. via a radio network or via data lines.

• 1 shows a schematic, partially sectional view of an exemplary device for additively manufacturing a three-dimensional object according to the invention.
• 2a to 2c serve to explain the term "partial cross-section" used in the application.
• 3 shows schematically an example of an inventive procedure for determining the starting trajectory.
• 4 shows schematically another example of an inventive procedure for determining the starting trajectory.
• 5a to 5c serve to explain the possibilities of defining a distance between the starting trajectory and the edge of an object cross-section.
• 6a to 6c serve to illustrate the procedure for determining the starting trajectories in several layers.
• 7 shows schematically the sequence of a method according to the invention for providing control data.
• 8 shows schematically the structure of a device according to the invention for providing control data.
• 9a and 9b show another example of the procedure for determining the starting trajectories in several layers.
• 10a and 10b show variants of the procedure according to 4 .

Based on 2a , 2b and 2c First, the term “partial cross-section” used in the present application is explained in more detail. 2a shows an exemplary object 200 that is to be manufactured by additive manufacturing. 2b shows a complete cross section 280 through the object 200 in a 2a shown plane A. In additive manufacturing, a layer of the build-up material is assigned to the cross section 280 and accordingly the plane A is selected parallel to the layer of the build-up material. As can be seen in 2b recognizes, the entire cross-section 280 comprises eight mutually delimited sub-areas 281, 282, 283, 284, 285, 286, 287, 288. Each of these sub-areas can be regarded as a partial cross-section that is completely delimited from the other areas of the entire cross-section 280. 2c shows an exemplary object 210, which is also to be manufactured by means of additive manufacturing, together with an overall cross-section 290 through the object 210 in a plane B. As in the case of the object cross-section 280, a layer of the build-up material is assigned to the cross-section 290 in the additive manufacturing and accordingly the plane B is selected parallel to the layer of the build-up material. As can be seen in 2c recognizes, in the entire cross-section 290 four sub-areas 291, 292, 293 and 294 differ from one another in their geometric properties. Sub-area 291 is essentially rectangular, with the exception of two semicircular bulges at the edge. Sub-area 292 is an arc. Sub-area 293 is a reflection of sub-area 292 on a horizontal line in the drawing plane and has the same shape and the same area as sub-area 292, but sub-area 293 differs from sub-area 292 because sub-area 293 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, borders on building material that is not to be solidified. According to the invention, only the partial area 291 is considered to be a partial cross-section, since it is the only one of the partial areas in which the minimum extension is greater than five times the distance between the trajectories in the partial area. To illustrate this fact, 2c exemplary trajectories are shown in each of the sub-areas. In sub-area 291, a large number of concentric trajectories can be seen, while in each of the sub-areas 292, 293 and 294 there is only a single trajectory (the trajectories 2992, 2993, 2994).

For a description of the invention, an additive manufacturing device according to the invention will first be described below using the example of a laser sintering or melting device with reference to 1 be described.

To build an object 2, the laser sintering or laser melting device 1 contains a process chamber or construction chamber 3 with a chamber wall 4. In the process chamber 3, a construction container 5 that is open at the top and has a container wall 6 is arranged. A working plane 7 (also called construction plane) is defined by the upper opening of the construction container 5, wherein the area of the working plane 7 that lies within the opening and can be used to build the object 2 is referred to as the construction field 8.

In the construction container 5, a carrier 10 is arranged that can be moved in a vertical direction V, to which a base plate 11 is attached, which closes off the container 5 at the bottom and thus forms its base. The base plate 11 can be a plate formed separately from the carrier 10, which is attached to the carrier 10, or it can be formed integrally with the carrier 10. Depending on the powder and process used, a construction platform 12 can also be attached to the base plate 11 as a construction base, on which the object 2 is built. The object 2 can also be built on the base plate 11 itself, which then serves as a construction base. In 1 the object 2 to be formed in the container 5 on the construction platform 12 is shown below the working level 7 in an intermediate state with several solidified layers, surrounded by unsolidified construction material 13.

The laser sintering or melting device 1 also contains a storage container 14 for a building material 15, in this example a powder that can be solidified by electromagnetic radiation, and a coater 16 that can be moved in a horizontal direction H for applying the building material 15 within the construction field 8. Optionally, a heating device, e.g. a radiant heater 17, can be arranged in the process chamber 3, which serves to heat the applied building material. An infrared radiator can be provided as the radiant heater 17, for example.

The exemplary additive manufacturing device 1 further contains an energy input device 20 with a laser 21, which generates a laser beam 22, which is deflected via a beam emitter 23, for example one or more galvanometer mirrors including the associated drive, and is focused onto the working plane 7 by a focusing device 24 via a coupling window 25, which is attached to the top of the process chamber 3 in the chamber wall 4. Even if this is in 1 is not shown, an additive manufacturing device can have two or more beam emitters 23. As a result, a manufacturing process can take place in a shorter time, since the build-up material can then be scanned and solidified at different locations with several beams at the same time.

The 1 The specific structure of a laser sintering or melting device shown is only an example for the present invention and can of course also be modified, in particular when using a different energy input device than the one shown.

The laser sintering device 1 further contains a control device 29, via which the individual components of the device 1 are controlled in a coordinated manner to carry out the construction process. Alternatively, the control device can also be installed partially or completely outside the additive manufacturing device. The control device can contain a CPU, the operation of which is controlled by a computer program (software). The computer program can be stored separately from the additive manufacturing device in a storage device, from where it can be loaded (e.g. via a network) into the additive manufacturing device, in particular into the control device.

During operation, the carrier 10 is lowered layer by layer by the control device 29, the coater 16 is controlled to apply a new layer of powder and the energy input device 20, i.e. in particular the beam emitter 23 and possibly also the laser 21 and/or the focusing device 24, are controlled to solidify the respective layer at the locations corresponding to the respective object by scanning these locations with the laser. In this application, reference is made to a unit 39 within the control device 29 responsible for controlling the energy input device 20 as the control device 39 of the energy input device. Nevertheless, it should be emphasized that a control device 39 of the energy input device can also be present outside the control device 29 in the same way (also in the form of a computer program), provided that it is ensured that the control device 39 of the energy input device can sufficiently interact with the control device 29 for the additive production of objects, i.e. in particular can exchange signals with the control device 29.

In the additive manufacturing device just described as an example, a manufacturing process takes place 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 specifies to an energy input device, in the case of the above laser sintering or laser melting device specifically the deflection device 23, for each point in time during the solidification process at which point on the working plane 7 radiation is to be directed.

8 shows a device 100 for providing control data for an additive manufacturing device. This contains a data access unit 101, a data model generation unit 102 and a control data provision unit 103. The operation of the device 100 for providing control data is explained with reference to 7 described as an example.

In the 8 In the device 100 shown for providing control data for an additive manufacturing device, the data access unit 101 first accesses computer-based model data of the object. In the 7 In the process sequence shown, this data access step is the first step S1. The computer-based model data contain a geometric description of the object, in particular a three-dimensional CAD model, although there are also other possibilities for geometric description, e.g. a description using a parameter set and a design specification. In this context, it is only important that the model data describe the geometric shape of at least a partial cross-section of an object to be manufactured, to which a layer of the construction material is assigned. In other words, the data access unit 101 can also access the entire model data (the complete CAD model) of the object to be manufactured (or of the objects to be manufactured if there are several objects to be manufactured in parallel in the additive manufacturing device).

The data access step (the first step S1) can also include forwarding the model data to a data model generation unit 102 described below, but the data model generation unit 102 can also get this data from the data access unit 101 or from a 8 read the memory (not shown) in which they are stored.

In the 7 In the second step S2 shown, the data model generation unit 102 now specifies a data model in which a solidification of the locations of the building material layer associated with the at least one partial cross-section is defined in a temporal sequence that corresponds to the movement of a beam along trajectories over the building material.

In particular, the temporal order in which the trajectories are traversed one after the other is specified.

After the second step S2 in 7 at least one data model has been created, are then processed by the 8 shown control data provision unit 103 provides control data for the generation of a control data record (in 7 this is step S3). Either the data model generated in the second step S2 can be provided as control information (control data) or the data model is reformatted into a control data set for better integration.

In the following, examples of the procedure in the second step S2 for different (partial) cross-sections and line courses of the trajectories are described.

The schematic 3 shows an exemplary partial cross-section 30, which is identical to the entire cross-section of an object and has an elliptical outer edge 31 for the building material that is not to be solidified and an elliptical inner edge 32 for the building material that is not to be solidified. To solidify the area between the two edges, it is advisable, due to the curved edges, not to move the beam along straight trajectories, but along curved trajectories that are in 3 are provided with the reference numerals 301 to 309. Since the trajectories in the example have a shape adapted to the shape of the edges 31 and 32, the number of trajectories required to scan the area of the cross-section is smaller than would be the case if straight trajectories were selected.

The procedure according to the invention is characterized in that when scanning the construction material, the first scanning step is not along a trajectory 303 or 309 closest to one of the edges 31, 32 (the edge trajectories), but along a trajectory spaced apart from the edges. In 3 The trajectory 301, along which the first scan is performed (the start trajectory), is shown with a solid line to distinguish it from the other trajectories. As can be seen in the figure, the two trajectories 302 and 303, which are scanned after the start trajectory 301, are located between the start trajectory 301 and the edge 31. The reference numbers in 3 are chosen such that trajectories with a higher reference number are traversed after trajectories with a lower reference number.

Of course, according to the invention, 3 a trajectory other than trajectory 301 can also be selected as the starting trajectory, 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 approach of the invention it would be sufficient if at least one point of the starting trajectory, in particular the starting point, is spaced from the edge, in the present case a starting trajectory can be defined in which all points are spaced from the edge.

4 shows another example of the procedure in the second step S2. The exemplary partial cross-section 40, which in the example corresponds to the entire cross-section of an object to be produced by means of additive manufacturing, has a rectangular shape. Unlike 3 the build material in the area of a build material layer associated with this cross-section is not scanned using trajectories that traverse the entire cross-section. Rather, the scanning is carried out segment by segment by defining segments that each correspond to a partial area of the cross-section. In 4 The rectangular segments 401, 402, 403, 404 and 405 are shown as examples. As is illustrated in the segment 401, the area of each segment is scanned along trajectories 91, 92, 93, 94 and 95. As is often the case, the sequence in which the trajectories are scanned within the individual segments is chosen to be the same in all segments. In 4 In each of the segments, the trajectories are scanned from top to bottom (in the image plane). This is done in 4 thereby causing shows that the trajectory to be scanned first in each of the segments is shown with a solid line, while the trajectories that follow in time are shown with dashed lines. In relation to segment 401, trajectory 91 is scanned first, then trajectory 92, then trajectory 93, then trajectory 94 and then trajectory 95. Although in 4 the trajectories within a segment are perpendicular to the edge of the segment, i.e. they enclose a 90° angle with the edge of the segment, the trajectories can also enclose a different angle with the edge of the segment, e.g. a 45° angle, although an angle of essentially 90° or exactly 90° is preferred.

If a segment-by-segment scanning is selected for scanning the area of a building material layer corresponding to a (partial) cross-section, then an inventive procedure can be implemented in such a way that within the cross-section, a segment is scanned first in which the trajectory scanned first in the segment is spaced from the edge of the cross-section. This trajectory is thus the starting trajectory when scanning the (partial) cross-section. In the example of 4 Accordingly, segment 401 is scanned first, followed by segments 402, 403, 404 and 405 in the order of the reference numbering. Alternatively, segments 402 and 403 could of course be scanned first, but not segments 404 and 405, in which the trajectory to be scanned first in time lies adjacent to edge 41. To indicate that the trajectory 91 to be scanned first in segment 401 is the starting trajectory for cross-section 40, trajectory 91 is shown with a thicker line.

10a and 10b show an embodiment of how the trajectories to be scanned in two adjacent segments can be advantageously determined in order to avoid excessive increases in the thickness of the solidified layer that occur during the solidification of an object cross-section.

10a shows a top view of a cross-section 1000 of an object to be produced by means of additive manufacturing, which has an exemplary circular shape with an outer edge 1100. As in the example of 4 also occurs in the example of 10a the scanning of the construction material segment by segment. As in 4 For the sake of clarity, only some of the segments are shown that are to be scanned in order to bring about a solidification of the construction material according to the cross section 1000. As in 4 show the 10a shown have a rectangular shape, with the trajectories along which the area of each segment is scanned being illustrated by arrows. In each of the segments, the trajectory to be scanned first in this segment is shown with 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 shown in dashed lines. Since in the example of 10a in the object cross-section the segment 1002 is solidified first, the trajectory 1020 is the starting trajectory for the cross-section 1000 and is shown with a thicker line for identification purposes.

When proceeding according to 10a one can first see that in segment 1001 the trajectory 1021 whose starting point 1021a is in the immediate vicinity of the starting point 1020a of the starting trajectory 1020 is scanned first. In addition, the trajectory 1021 in segment 1001 is traversed in the opposite direction to the starting trajectory. By such a procedure it can be achieved that material that has accumulated at the starting point of the starting trajectory is at least partially transported away with the scanning of the first trajectory in the neighboring segment, thereby reducing the layer elevation.

10b shows a modification of the procedure according to 10a , where the same reference numerals also indicate the same features. When proceeding according to 10b all trajectories in a segment 1001, 1002 are scanned in the same direction. In addition, all trajectories start at the boundary 1012 between the two segments 1001 and 1002. In this way, layer elevations that tend to occur at the beginning of the trajectories in the first scanned segment 1002 can be at least partially eliminated.

Based on 5a to 5c Possible definitions of a distance of a starting trajectory from the edge of a partial cross-section are explained below. 5a to 5c show a partial cross-section 50, which for the sake of simplicity is identical to the entire cross-section of the object, is exemplary square and has an edge 51. In 5a Four trajectories 501, 502, 503, 504 are shown in the partial cross-section 50, of which the trajectory 501 is defined as the starting trajectory and is therefore shown with a thicker line. The figure shows three sections 510, 511 and 512 of the starting trajectory 501. As can be seen, two further trajectories 502 and 503 lie between the section 510 and the edge 51 of the object cross-section 50 in a direction perpendicular to the course of the section 510. Next There are three further trajectories 502, 503 and 504 between the partial section 511 and the edge 51 of the object cross-section 50 in a direction perpendicular to the course of the partial section 511. Finally, there is a further trajectory 502 between the partial section 512 and the edge 51 of the object cross-section 50 in a direction perpendicular to the course of the partial section 512. Thus, according to the invention, the trajectory 501 can be defined as the starting trajectory, since there is at least one partial section of the trajectory 501 in which at least one further trajectory lies between the starting trajectory and the edge.

While based on 5a the preferred case was explained in which the distance of the sections or points of the starting trajectory from the edge was determined in a direction perpendicular to the course of the sections or the starting trajectory through the points, a determination of the distance in this way is not absolutely necessary, which can be seen from 5b and 5c is explained. In 5b a starting trajectory 505 and two further trajectories 555 and 556 are shown. The trajectories 555 and 556 lie 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 lie in a direction parallel to the course of the starting trajectory (more precisely in a course direction of the initial section of the starting trajectory) between the starting point 550 of the starting trajectory 505 and the edge 51 of the object cross-section 50. While in the example of the 5a the distance between linear sections of the starting trajectory and the edge was determined, here the distance of a single point of the starting trajectory, here the starting point, to the edge is determined. In 5b According to the invention, the trajectory 505 can be defined as the starting trajectory, since then at least one further trajectory lies between at least one point, here the starting point, the starting trajectory and the edge. As in 5b As shown, trajectories 555 and 556 are neither parallel nor perpendicular to each other. In addition, trajectories 555 and 556 are neither parallel nor perpendicular to starting trajectory 505.

5c shows a starting trajectory 506, a circular arc-shaped partial section 560 of the starting trajectory 506 and the trajectories 565 and 566. The trajectories 565 and 566 lie between the partial section 560 of the starting trajectory 506 and the edge 51 of the object cross-section 50. In particular, the trajectories 565 and 566 lie in a radial direction of the partial section 560 of the starting trajectory, based on the circular arc shape, between the partial section 560 of the starting trajectory 506 and the edge 51 of the object cross-section 50. The trajectory 506 can thus be defined according to the invention as a starting trajectory, since there is at least one point, here even a plurality of points (the partial section 560), for which it applies that at least one further trajectory lies between the starting trajectory and the edge. As in 5c As shown, the trajectories 565 and 566 are neither parallel nor perpendicular to each other. In addition, the trajectories 565 and 566 are neither parallel nor perpendicular to the (circular arc-shaped) course of the partial section 560 of the starting trajectory 506.

As shown by the 5a , 5b and 5c should be illustrated, it is irrelevant for the implementation of the present invention in which direction with respect to the direction of the starting trajectory the further trajectories lie between the edge and the starting trajectory. The directions of the further trajectories that lie between a point or partial section of the starting trajectory and the edge also play no role for the implementation of the invention.

Even if the uniformity of the thickness of the solidified layer can be improved by the inventive procedure, the greatest thickness in the solidified building material layer within a partial cross-section still usually occurs in the area of the starting trajectory. Since an object to be manufactured usually has many object cross-sections lying on top of each other (corresponding to many building material layers lying on top of each other), adding the excessive thicknesses in the individual layers can lead to an undesirably large variation in the total height (extension in the z-direction) of the object. In particular, the variation in height can be so large even during the manufacturing process that a coating element collides with projections of solidified building material protruding upwards from an already solidified layer. Such undesirable behavior can be prevented by means of the method described below with reference to 6a to 6c described approach.

6a shows a top view of a cross-section 60 of an object to be produced by means of additive manufacturing, which has an exemplary circular shape with an outer edge 61. As in the example of 4 also occurs in the example of 6a the scanning of the construction material segment by segment. As in 4 For the sake of clarity, only some of the segments are shown that are to be scanned in order to bring about a solidification of the construction material according to the cross section 60. As in 4 show the 6a The two segments 601 and 602 shown have a rectangular shape, with the trajectories along which the area of each segment is scanned being illustrated by arrows. In each of the Segments, the trajectory to be scanned first in this segment is shown with a solid line, in segment 601 this is trajectory 691 and in segment 602 this is trajectory 692, while the trajectories that follow in time are shown with dashed lines. Since in the example of 6a Since segment 601 is solidified first, trajectory 691 is the starting trajectory for cross section 60 and is shown with a thicker line for identification purposes.

6b shows in plan view another cross section 60' through the same object to which 6a The cross section 60' refers to a position in the z-direction that is higher than the position to which the cross section 60 in 6a In other words, relative to the orientation of the object in space during its manufacture, the cross section is 60' from 6b at a height greater than the cross section 60 of 6a . The cross section 60' is thereby assigned a building material layer which, during manufacture, is located above the building material layer which corresponds to the cross section 60 of 6a is assigned to.

For simplicity, the cross section has 60' in 6b the same shape and size as the cross section 60 in 6a and segments 601' and 602' in 6b have the same shape and size as segments 601 and 602 in 6a However, it can be seen that the segments 601' and 602' are smaller than the segments in 6a are rotated clockwise by 25°. Other possible angles of rotation are, for example, 45°, 65°, 85°, 105°, 115°, 125°, 135°, 155°, 175°. This also applies to the trajectories in the segments 601' and 602', e.g. the trajectory 691' which is the first to be consolidated in segment 601' and the trajectory 692' which is the first to be consolidated in segment 602'. In 6b trajectory 692' is the starting trajectory.

6c shows in plan view a superposition of the cross sections 60 and 60' of the 6a and 6b together with the 6a and 6b shown segments and trajectories. In the superposition, it can be seen that the trajectory 691' to be scanned first in segment 601' of cross section 60' overlaps the start trajectory 691 of cross section 60. If segment 601' in cross section 60' were to be solidified first, then trajectory 691' would become the start trajectory of cross section 60'. At the point where the start trajectories 691 and 691' overlap, the increases in layer thickness would then be added together. Depending on the application, adding the increases in layer thickness in a small area (in the hypothetical example, the start trajectories 691 and 691' only intersect at one point) may be acceptable. For some applications, however, the presence of an overlap of the starting trajectories can be disadvantageous or undesirable, in particular if the layers 60 and 60' are only spaced apart by a small number of further layers (for example, less than 64 layers, preferably less than 32, particularly preferably less than 16 layers). Therefore, the example of the 6 proposes that in the cross section 60' the segment 602' is solidified first, whereby the trajectory 692' becomes the starting trajectory for the cross section 60', as is also the case in 6b is shown.

9a and 9b show another exemplary approach. 9a is very similar to 6a and shows a top view of a cross-section 90 of an object to be produced by means of additive manufacturing, which has an exemplary circular shape with an outer edge 91. As in the example of 6a also occurs in the example of 9a the scanning of the construction material segment by segment. As in 6a For the sake of clarity, only some of the segments are shown that are to be scanned in order to bring about a solidification of the construction material according to the cross section 90. As in 6a show the 9a shown two segments 901 and 902 have a rectangular shape, whereby the trajectories along which the area of each segment is scanned are again illustrated by arrows. In each of the segments, the trajectory to be scanned first in time is shown with a solid line, in segment 901 this is trajectory 991 and in segment 902 this is trajectory 992, while the trajectories that follow in time are shown in dashed lines. Since in the example of 9a Since segment 901 is solidified first, trajectory 991 is the starting trajectory for cross section 90 and is shown with a thicker line for identification purposes.

9b shows in plan view another cross section 90' through the object of 9a . The cross section 90' refers to a position in the z-direction that is higher than the position to which the cross section 90 in 9a In other words, relative to the orientation of the object in space during manufacture, the cross section is 90' from 9b at a height greater than the cross section 90 of 9a . The cross section 90' is thereby assigned a building material layer which, during manufacture, is located above the building material layer which corresponds to the cross section 90 of 9a is assigned to.

For simplicity, in this example the cross section is 90' in 9b the same shape and size as the cross section 90 in 9a and segments 901' and 902' in 9b have the same shape and size as segments 901 and 902 in 9a . In addition, segments 901' and 902' and the trajectories therein also have the same position and orientation in the construction plane or layer plane as segments 901 and 902 and the trajectories therein in 9a . However, when solidifying the cross section 90', the trajectory 991' is not selected as the starting trajectory (and thus the segment 901' is selected as the starting segment), but rather the trajectory 992' (and thus the segment 902' is selected as the starting segment). This is because if the trajectory 991' is selected as the starting trajectory, it would completely overlap the starting trajectory 991 when the underlying cross section 90 is solidified, which would cause the layer elevations to add up.

As an alternative to the 9b Using the procedure shown, an overlap of the starting trajectories could also be avoided or reduced by spatially offsetting the segments 901' and 902' and/or the trajectories contained therein relative to the segments 901 and 902 and/or the trajectories contained therein in the layer plane or construction plane (without rotation). Depending on the extent of the offset, the (now spatially offset) trajectory 991' could then be the starting trajectory.

Finally, it is also possible to select the starting trajectory from the trajectories in a layer, in particular a second layer following a first layer, using a random generator. This procedure can be chosen in particular if the segment and/or trajectory patterns in the successive layers are the same and/or have the same orientation in the construction plane.

Especially when partial cross-sections in superimposed building material layers are scanned segment by segment, a change in the orientation of the trajectories in the layer plane or building plane (a rotation) can sometimes ensure that the starting trajectories in the different building material layers do not overlap (do not lie on top of each other at any point), even though the scanning order of the segments in the different layers is the same.

In general, it is advantageous if the position and orientation of the trajectories in the plane are different in different layers, as this counteracts the formation of anisotropic properties or preferred directions in the manufactured object. If the orientation of the trajectories in superimposed layers of building material is the same, then the trajectories in these layers should preferably not lie directly on top of each other, but should be offset horizontally from each other, in particular in a direction perpendicular to the direction of the trajectories.

A simple way to prevent anisotropies is to change the orientation of the trajectories in the next layer, or at least in the layer after that. If one assumes that the shape of the trajectories does not change from layer to layer, a change in the orientation of the trajectories corresponds to a rotation in the building plane or layer plane. The angle of rotation should preferably not be an integer part of 360°, and particularly preferably should not have a common divisor of 360° other than one. This prevents the orientation of the trajectories from repeating in different building material layers.

Claims (17)

Computer-aided method for providing control data for an additive manufacturing device (1) for producing a three-dimensional object (2) by means of the same, wherein the additive manufacturing device is designed such that objects are produced by means of the additive manufacturing device by applying a building material layer upon layer and solidifying the building material in a layer plane (7) by supplying radiation energy to those locations in each layer that are associated with an object cross-section in this layer, wherein the method for providing control data comprises: a first step (S1) of accessing computer-based model data of a number of partial cross-sections of the object to be produced, each of which comprises a partial area of an object cross-section and a section of the edge of this object cross-section, a second step (S2) of generating a data model of the number of partial cross-sections, wherein in the data model a scanning of the locations of the number of partial cross-sections with a number of rays (22) along a plurality of trajectories (54) in the layer plane (7) is specified, wherein in at least one of the number of partial cross-sections a sequence of scanning the trajectory rien is defined such that a start trajectory is scanned first, wherein at least one point of the start trajectory is spaced from the edge of the object cross-section in the layer plane such that at least one further trajectory lies between the at least one point and the edge, preferably at least two further trajectories lie between the at least one point and the edge, and a third step (S3) in which control data corresponding to the data model generated in the second step (S2) are provided for generating a control data set for producing the object by means of the additive manufacturing device. Procedure according to Claim 1 , wherein in the second step (S2) a data model of at least one partial cross-section in a first building material layer and at least one partial cross-section in an overlying second building material layer is generated and a starting trajectory is selected for the partial cross-section in the second building material layer which at most partially, preferably not at all, overlaps with the starting trajectory for the partial cross-section of the first building material layer. Procedure according to Claim 2 , wherein the starting trajectory in the partial cross-section of the second building material layer is selected such that it has a different distance from the edge of the object cross-section in the layer plane than the starting trajectory in the partial cross-section of the first building material layer, wherein the other distance is characterized by the fact that a different number of further trajectories lie between the starting trajectory or a point thereof and the edge. Procedure according to Claim 2 or 3 , wherein the trajectories in the second building material layer are rotated relative to the trajectories in the first building material layer by an angle which is different from 0°, 90° and 270°. Procedure according to Claim 4 , wherein the trajectories in the second building material layer are rotated relative to the trajectories in the first building material layer by an angle which is greater than 90° and/or less than 270°. Procedure according to Claim 5 , wherein the angle is greater than 120° or less than 120°, preferably greater than 100° and less than 140°. Method according to one of the preceding claims, wherein the starting trajectory is selected from the plurality of trajectories to be scanned in the partial cross-section using a random generator. Method according to one of the preceding claims, wherein the trajectories in a second building material layer have the same shape and orientation to one another as the trajectories in a first building material layer. Method according to one of the preceding claims, wherein a partial cross-section is solidified segment by segment, wherein a segment corresponds to a partial area of the partial cross-section and each segment is solidified by scanning along a plurality of trajectories in the layer plane (7). Procedure according to Claim 9 , wherein the segments have a rectangular shape and the trajectories in the segments enclose an angle between 5° and 175°, preferably between 45° and 135°, particularly preferably between 85° and 95°, with an edge of the segment. Procedure according to Claim 10 , wherein a trajectory lying in one of the segments is defined as a starting trajectory, wherein the starting trajectory is defined such that it is scanned in a direction pointing away from a boundary of the segment to an adjacent neighboring segment, and wherein the first of the trajectories to be scanned in the adjacent neighboring segment is defined such that it is scanned starting at a location adjacent to the starting trajectory in a direction pointing away from the boundary. Device for providing control data for an additive manufacturing device (1) for producing a three-dimensional object (2) by means of the same, wherein the additive manufacturing device is designed such that objects are produced by means of the additive manufacturing device by applying a building material layer upon layer and solidifying the building material in a layer plane (7) by supplying radiation energy to those locations in each Layer that are assigned to the cross-section of the object in this layer, wherein the device for providing control data comprises: an access unit that is designed to access computer-based model data of a number of partial cross-sections of the object to be produced, each of which comprises a partial area of an object cross-section and a portion of the edge of this object cross-section, a data model generation unit that is designed to generate a data model of the number of partial cross-sections, wherein in the data model a scanning of the locations of the number of partial cross-sections with a number of rays (22) along a plurality of trajectories (54) in the layer plane (7) is specified, wherein the data model generation unit is designed to specify an order of scanning of the trajectories in at least one of the number of partial cross-sections such that a start trajectory is scanned first, wherein at least one point of the start trajectory is spaced from the edge of the object cross-section in the layer plane such that at least one further trajectory lies between the at least a point and the edge, preferably at least two further trajectories lie between the at least one point and the edge, and a control data provision unit which is designed to provide control data corresponding to a data model generated by the data model generation unit for the generation of a control data set for the production of the object by means of the additive manufacturing device. Method for controlling an energy input device of an additive manufacturing device (1) for producing a three-dimensional object (2) by means of the same, wherein the object is produced by means of the additive manufacturing device by applying a building material layer by layer and solidifying the building material in a layer plane (7) by supplying radiant energy to those locations in each layer that are associated with the cross-section of the object in this layer, wherein the additive manufacturing device for supplying radiant energy has an energy input device that is designed to solidify a number of partial cross-sections of the object to be produced, each of which comprises a partial area of an object cross-section and a section of the edge of this object cross-section, by scanning the locations of the number of partial cross-sections with a number of beams (22) along a plurality of trajectories (54) in the layer plane (7), wherein in the method, for at least one of the number of partial cross-sections, an order of scanning the trajectories is defined such that first a Start trajectory is scanned, wherein at least one point of the start trajectory is spaced from the edge of the object cross-section in the layer plane such that at least one further trajectory lies between the at least one point and the edge, preferably at least two further trajectories lie between the at least one point and the edge. Additive manufacturing method for producing a three-dimensional object (2) by means of an additive manufacturing device, wherein in the additive manufacturing method a method according to Claim 13 is executed. Device for controlling an energy input device of an additive manufacturing device (1) for producing a three-dimensional object (2) by means of the same, wherein the objects are produced by means of the additive manufacturing device by applying a building material layer by layer and solidifying the building material in a layer plane (7) by supplying radiant energy to those locations in each layer that are assigned to the cross-section of the object in this layer, wherein the additive manufacturing device for supplying radiant energy has an energy input device that is designed to solidify a number of partial cross-sections, each of which comprises a partial area of an object cross-section and a section of the edge of this object cross-section, to scan the locations of the number of partial cross-sections with a number of beams (22) along a plurality of trajectories (54) in the layer plane (7), the device has a scanning control unit that is designed to specify a sequence of scanning the trajectories for at least one of the number of partial cross-sections such that first a starting trajectory is scanned, wherein at least one point of the starting trajectory is spaced from the edge of the object cross-section in the layer plane such that at least one further trajectory lies between the at least one point and the edge, preferably at least two further trajectories lie between the at least one point and the edge. Additive manufacturing device for producing a three-dimensional object (2) by means of the same, wherein the additive manufacturing device comprises a device according to Claim 15 has. Computer program comprising a sequence of instructions which, when executed, performs a method according to one of the Claims 1 until 11 and/or a procedure according to one of the Claims 13 or 14 is implemented.

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