WO2018206581A1

WO2018206581A1 - Position-specific input of energy

Info

Publication number: WO2018206581A1
Application number: PCT/EP2018/061875
Authority: WO
Inventors: Ludger HÜMMELER
Original assignee: Eos Gmbh Electro Optical Systems
Priority date: 2017-05-09
Filing date: 2018-05-08
Publication date: 2018-11-15
Also published as: DE102017207832A1

Abstract

A method for providing control data for a generative layered construction apparatus involves a number of layer data records being accessed in a first step (S1), wherein a layer data record has a respective data model of a construction material layer to be selectively reinforced during production. In a second step (S2), at at least one starting point (P1), at which reinforcement is intended to take place, in at least one data model, the interval of time (155) between the time (154) at which this starting point (P1) is scanned and the time (154) at which another identified point (N1) in the number of layer data records is scanned is determined. In a third step (S3), the number of layer data records is modified such that the value of an energy input parameter for scanning the at least one starting point (P1) and/or the value of an energy input parameter for scanning the other identified point (N1) is specified on the basis of the magnitude of their interval of time, and in a fourth step (S4), the layer data records modified in the third step are provided as control data for producing the three-dimensional object by means of the generative layered construction apparatus.

Description

POSITION SPECIFIC ENERGY ENTRY

The invention relates to a method and a device for providing control data for a generative layer construction device, a correspondingly adapted generative layer construction method, a suitably adapted generative layer construction device, a correspondingly adapted computer program and a correspondingly adapted computer-readable storage device.

Generative layer construction devices and related methods are generally characterized by fabricating objects in them by solidifying a shapeless building material layer by layer. The solidification can be brought about, for example, by supplying heat energy to the building material by irradiating it with electromagnetic radiation or particle radiation (eg laser sintering (SLS or DMLS) or laser melting or electron beam melting) or by inducing a crosslinking reaction in the building material (eg stereolithography). The devices and processes originally used in prototype construction are increasingly used for series production, for which the term "additive manufacturing" has become common. In order to be able to produce the objects with high precision in generative layer construction processes, it is important that the building material within each of the layers is solidified as uniformly as possible. This problem is addressed by WO 2015/091875 Al in the field of electron beam melting. In particular, this involves the scanning of an object cross-section with the electron beam in mutually parallel scanning lines (scan lines). As a result of this form of scanning of the building material within the object cross-section, the electron beam is moved over the building material in a manner similar to the hatching of a surface, which is why this way of directing the electron beam onto the building material is also referred to as "hatching" in technical jargon.

In WO 2015/091875 AI it is stated that the amount of energy supplied to the material depends on whether the scan lines are long or short. For too long scan lines, an insufficient amount of energy is observed, while for short scan lines an excessive amount of energy is observed. To solve the problem, WO 2015/091875 A1 proposes to determine the scanning time of the material along the longest scan line occurring in the hatching of the object cross section and to insert a waiting time for all shorter scan lines before or after the scanning of the scan line, so that the sum of sampling time a scan line and waiting time always corresponds to the sampling time for the longest scan line.

The procedure according to WO 2015/091875 A1 is suitable for ensuring a more homogeneous melting behavior during electron beam melting. A disadvantage of this method, however, is that is extended by the insertion of waiting times of the manufacturing process, which is particularly in the field of "Additive Manufacturing" of disadvantage, since there the objects should be produced as possible within a shorter production time.

In view of the problem described above, it is an object of the present invention to provide a method and an apparatus by means of which objects can be produced in a short time with high quality by means of a generative layer construction method, in particular an "additive manufacturing" method. The object is solved by a computerized method according to claim 1, a generative layer construction method according to claim 14, an apparatus according to claim 15, a computer program according to claim 17 and a computer readable memory device according to claim 18. Further developments of the invention are claimed in the dependent claims. In particular, a device according to the invention can also be developed by features of the method according to the invention characterized 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 for the development of another device according to the invention, even if this is not explicitly stated.

A computer aided method of providing control data to a generative layer building apparatus for fabricating a three-dimensional object, wherein the object is fabricated by the generative layer building apparatus by applying a building material layer by layer and solidifying the building material by applying radiant energy to locations in each layer corresponding to the layer Assigned cross section of the object in this layer by these sites are scanned by means of an energy input device based on a set of energy input parameter values with energy radiation, has a first step Sl, in which a number of layer records is accessed, wherein a layer data set each a data model of a has during the production selectively to be consolidated building material layer and in the data model an object cross-section corresponding locations are marked, where an Verfes tion of the building material in the appropriate layer to take place. The method is characterized in that in a second step S2 in at least one data model of a layer data set at at least one output point at which a solidification is to take place, the time interval between the time of sampling this output point and the time of sampling another designated location in is determined in a third step S3, the number of layer data sets is changed such that the value of an energy input parameter for the scanning process is determined in accordance with the number of layer data sets, preferably another identified point in the layer data record. stung the at least one output point and / or the value of an energy input parameter for the scanning of the other marked location is specified in dependence on the size of their time interval and in a fourth step S4 the modified layer data sets in the third step as control data for the production of the three-dimensional object means the generative layer building apparatus are provided.

Generative layer construction devices and methods to which the present invention relates are, in particular, those in which energy, such as electromagnetic radiation or particle radiation, is selectively applied to a layer of the building material to thereby heat the building material. For this purpose, the energy input device may for example comprise a laser or an electron beam source. In this case, the building material is partially or completely melted by means of the energy introduced by the radiation, whereby the constituents of the building material (for example powder grains) connect to one another. After cooling, the building material is then present as a solid. Since the transitions between superficial melting (sintering) and complete melting (melting) are fluid, the terms "sintering" and "melting" are used synonymously in the present application and do not distinguish between sintering and melting.

As a building material in a generative layer construction process according to the invention, various materials can be used, preferably powders or pastes or gels, in particular metal powders, but also plastic powders, ceramic powders or sand, whereby the use of filled or mixed powders is also possible.

It should be noted at this point that not only one object but also several objects can be produced simultaneously by means of a generative layer construction device according to the invention. Whenever reference is made in the present application to the manufacture of an object, it is to be understood that the same description applies equally to generative layer construction methods and apparatus in which multiple objects are manufactured simultaneously. It should also be noted at this point that in In the present application, the term "number" is always to be understood as meaning "one or more".

Control data in the sense of the present application are specifications or specifications on the basis of which the production process of an object can be controlled by means of a generative layer construction device. Such control of the manufacturing process is usually done by means of a control instruction set (often referred to as a control data set), which is a sequence of instructions to apply layers of building material one after the other and areas of the respective layers corresponding to the cross section of an object to be manufactured, to irradiate with energy radiation to solidify the building material.

In detail, a control data set is based on a computer-based model of the object (s) to be produced, preferably a CAD model. The control data record specifies, for each build-up material layer during production, the points at which solidification of the build-up material is to be effected by irradiation. Furthermore, a control data set often also specifies the thickness of the layer application and moreover often also contains production-specific information, for example with regard to the position and orientation of the objects in the generative layer construction device or with respect to a diameter of the energy beam bundle when hitting the building material. As a rule, the control data set contains all the data required for controlling the energy input device, which, inter alia, defines the energy density of the energy radiation and optionally the travel speed of the beam bundle via the building material.

The control data set can thus be regarded as a totality of all control data predetermined for the control of the production process in a generative layer building apparatus. The control data related to a single layer are also referred to as a shift data record. A shift data record is therefore a data record which contains a data model of a build material layer to be consolidated at the locations of an object cross section during the production process. Such a shift record is usually generated in layers of a CAD model of the object to be produced (referred to in the jargon as "slicing"). However, it is also conceivable to extract a two-dimensional representation of the object cross-section to be consolidated in one layer by means of one or more beams in a different way from the computer-based CAD model of the object. The layer data record may, but need not, contain further information regarding the production of the object cross section, eg the layer thickness, the diameter of a beam impinging on the building material, etc.

When referring to access to a number of shift records, it is meant that a number of shift records are read from a memory or the data corresponding to the number of shift records is received over a network. Not necessarily the data models of all building material layers to be selectively solidified during production have to be read together (ie simultaneously). It is also possible that there is a larger time interval between the accesses to the data models of different layers, for example, the data model of a building material layer (a layer data set) is read in each case as needed during a manufacturing process of an object and then a modified layer material record for the building material layer during the Manufacturing process is integrated into the control record.

To avoid misunderstandings, it should be emphasized here that, when referring to the third step, a change in the number of data records refers to the fact that shift records themselves are changed and not their number. In addition, layer data sets modified according to the third step need not be provided individually for a generative layer construction process. Rather, several modified shift records can be collected first and then provided in their entirety for integration into a control record.

According to the invention, at an area of the building material which is to be solidified, an energy amount which is exactly adequate for this location can be incorporated into the building material for solidification of the same. will wear. As a result, the actual conditions at a point at which energy is to be entered, ie in particular the temperature at this point, are taken into account. This is achieved by taking into account the points in time and places where energy was introduced into the building material for the determination of the amount of energy to be entered at a certain point. The invention takes into account that after a successful energy input, the heat energy supplied to the building material by heat conduction and thermal radiation propagates over time to areas away from the irradiated point. In particular, due to thermal propagation in practice during the manufacturing process of an object, there is often no homogeneous temperature of the build material within the unconsolidated regions of the cross sections of an object. According to the invention, the time interval is therefore taken into account for the dimensioning of the energy amount to be supplied to at least one other point at which energy has already been supplied. If solidification of the other marked point is provided only after solidification of the exit point, alternatively the energy to be entered can be adjusted (as it were anticipatory) already at the exit point. Of course, the energy to be entered can also be adapted to the time interval both at the starting point and at the other marked point, eg in both places to the same extent.

Normally, the points which have a very short time interval to the point to be irradiated lie in the same cross section of the object. Nevertheless, even locations in already completely irradiated object cross-sections can influence the temperature at a point still to be irradiated. For example, it may happen that an already completely irradiated object cross-section in the layer immediately below the point to be irradiated still contains a lot of heat energy, which is emitted upward. Accordingly, it may be useful to determine a time difference between the solidification of the point to be irradiated and the solidification of a point in an underlying layer, for example, the immediately underlying point in the immediately underlying layer, and on this basis the energy to be entered at the to be sized spot to be irradiated. The inventive approach is therefore not limited to the consideration of marked for solidification points within the same object cross-section.

The determination of the time interval between the time of sampling one exit point and the time of the scanning of another point marked for solidification is possible if in the number of shift data sets not only the locations at which solidification of the construction material is to take place are indicated also the chronological order in which these places are to be irradiated. Preferably, not only the time sequence but also the time intervals on a time scale (preferably in real time) are specified for the locations to be irradiated in the number of shift data sets. If a temporal sequence and / or a time scale, according to which the locations are to be solidified within at least a subarea of an object cross section, are not defined in the corresponding data model of a shift data set, the method determines the locations at which time intervals of the scan are determined , previously performed a temporal order of the scan and possibly also an assignment of the sampling times to a time scale.

There are several parameters that can be changed to change the energy input when sampling with energy radiation. One possible energy input parameter to be changed is the energy density, ie the radiation energy per unit area of the energy radiation used for scanning the building material, another exemplary parameter being the speed of the sampling of the building material.

In the third step S3, the value of an energy input parameter for the sampling of the at least one output location and / or the value of an energy input parameter for the sampling of the other identified location is preferred as a function of the size of the spatial distance between them and / or depending on the type and the nature of the building material specified at one of these locations. Since the sites to be consolidated are defined in the layer data records or the corresponding data models of a building material layer, it is possible to determine spatial distances between sites to be consolidated. If the spatial distance between a point of origin and another point marked for solidification is taken into account and / or the condition of the building material is taken into account, then the heat transfer can be specifically determined between the two points within a certain time and for the determination at the exit point energy to be used, if this starting point is solidified after the other designated point. Alternatively, the determined heat transfer can be used for determining the energy to be registered at the other designated location, provided that it is solidified after the exit point. In particular, by taking into account the nature and nature of the building material, the amount of energy to be entered can be set very precisely.

In the method, the time within which points assigned to the cross sections of the object in the layers are scanned with energy radiation is preferably subdivided into time segments of preferably equal size, and a time interval between the time intervals respectively assigned to the positions is determined.

In such a procedure, a time scale is introduced at which the times for scanning different locations in the number of shift records are determined. Preferably, the time scale is the real time during the construction process. It is conceivable, for example, to provide places to be consolidated in a data model with a time stamp which determines the time of their consolidation. Preferably, minimal large time intervals are introduced in this procedure, so to speak introduced a granularity of time. This means that the same solidification time, ie the same period of time on the time scale, is assigned to different points to be solidified in succession. This reduces the amount of data to be processed. Furthermore, this simplifies the determination of time intervals, since a time interval is not determined for all locations must be, but only a time interval between two periods, which then applies to all of these periods assigned locations.

If a corresponding time scale is not yet present in a data model of a shift data record which is accessed in the first step S 1, such a time scale is added to the data model or a time scale already existing in the data model is modified accordingly before time intervals are determined.

Further, in particular if the other identified location is assigned a later time segment than the at least one output location, in the third step S3 the value of an energy input parameter for scanning the other identified location is determined as a function of the value of an energy input parameter for the sampling of the at least one output location and / or, in particular if the at least one output location is assigned a later time segment than the other identified location, in step S3 the value of an energy input parameter for the sampling of the at least one output location is defined as a function of the value of an energy input parameter for the sampling of the other identified location ,

Through such a procedure, an amount of energy to be entered can be exactly matched to the energy amounts already entered elsewhere. As a result, a dynamic adaptation of the amounts of energy to be registered becomes possible if the method is carried out for a plurality of locations, in particular all locations which are to be solidified in an object, in particular within an object cross-section.

In a variant of the method, in the first step S1, a slice data record is accessed in which a sampling of the locations of at least one subregion of the object cross section is specified with at least one energy beam bundle by specifying temporally successive scan lines for the movement of the at least one energy beam bundle, W

11 in the second step S2 for at least one first scan line, preferably all scan lines, at at least two different output points on this first scan line, the time interval between the time of sampling this output point and the time of sampling a neighboring point of this point on a temporally subsequent second scan line determines

in the third step S3, the shift data record is modified in such a way that different values of an energy input parameter for the scanning of the at least two different output points and / or different values of an energy input parameter for the scanning of the respective neighboring points are specified for different time intervals, and

in the fourth step S4, the layer data set modified in the third step is provided for the control of the production of the three-dimensional object by means of the generative layer construction device.

The method can be used particularly advantageously if, during scanning of the building material at points corresponding to an object cross-section, an energy beam is moved in scanning lines (scan lines) similar to the hatching of a surface over the building material (also referred to as "hatching" in technical jargon). Alternatively, the energy beam can be moved to scan lines parallel to the contour of a partial region of the object cross-section (referred to in the jargon as "onion-ring hatching" or "onion-ring-like exposure") or else on a spiral path.

The term "beam" is intended to express that not only are rays that have a small cross section when hitting the building material, but also rays that have, for example, a linear cross-section or even radiation that at the same time in a larger area of the building material (So flat) is registered. In any case, but in particular when the energy input is flat, an energy density specified for the corresponding energy beam bundle always refers to the energy density averaged over the impact surface. Furthermore, it does not matter to the present invention, whether the energy input device one or more energy beam can successively or simultaneously focus on the building material, as far as adjacent scan lines are scanned in succession. In particular, however, the present invention can be advantageously used in the presence of only one energy beam.

In particular, such an approach makes it possible to adapt the energy input parameters to the actual requirements for optimum consolidation of the building material even within a scan line. In this case, the neighboring sites are preferably other sites marked for solidification which lie on a temporally subsequent second scan line. Ultimately, all that matters is that the amount of energy to be entered at the exit point or the neighboring point is determined as a function of the time interval between these two points, which are located on temporally successive scan lines, in particular on temporally consecutive scan lines.

Preferably, in the variant of the method just described, the respective adjacent location on the temporally subsequent second scan line is selected within a range of a predetermined dimension around that point on the second scan line at which a solder built at the exit location on the first scan line is second consecutive Scan line intersects.

Which point is used on a temporally subsequent second scan line as a neighbor point to a starting point on the first scan line is initially assumed to the discretion of the expert. Advantageously, one will use a location on the subsequent second scan line as a neighboring point, which is located as close as possible to the exit point on the first scan line. The preferred procedure just described here provides guidance on which location on the temporally subsequent second scan line is to be selected as neighbor location.

Preferably, the just-mentioned predetermined dimension is 40%, more preferably 20%, even more preferably 10% of the distance between the exit point and the point on the second scan line, at which a solder built at the exit point on the first scan line intersects the temporally subsequent second scan line.

Of course, theoretically, the ideal neighbor location to use for the method would be at the intersection of the solder with the second scan line. In practice, however, it has been found that it is already advantageous if the neighboring point lies within an area on the second scan line whose extension depends on the distance between the starting point and the intersection of the solder with the second position.

In the variant of the method, for different time intervals, different amounts of radiation energy to be entered per unit area are preferably specified at the at least two different output locations and / or the respective neighboring locations.

Preferably, the amount of energy to be entered is adjusted by adjusting the energy density in the beam, that is to say the radiation energy per unit area. In the case of a planar expansion of the beam at the point of impact on the building material, the energy density is normally used as the mean value of the radiation energy per unit area, for example by using e.g. the amount of energy in the beam is divided by the area of the point of impact of the radiation on the building material.

Still more preferably, the specified amount of radiant energy to be input per unit area monotonically coincides with the determined time intervals and is in particular specified the lower the shorter the time interval.

The shorter the time interval between two points, the greater the influence will be the irradiation of one point to the other point. Therefore, if the irradiation of the neighboring site is to take place a short time after that of the exit point, then at the neighboring site much residual heat in the building material will be present. Therefore, it is advantageous to choose the amount of radiation energy to be entered per unit area smaller. W 201

14

Conversely, a longer exposure of the exit site at the neighboring site is less noticeable (e.g., by a not so great increase in temperature). The amount of radiation energy to be entered per unit area will accordingly have to be specified higher.

In a further preferred embodiment of the variant of the method, different movement speeds of an energy beam are specified for different time intervals at the at least two different output locations and / or the respective neighboring locations.

In this embodiment, the amount of energy to be entered at one point is adjusted by a change in the speed of movement of the energy beam. Due to the faster movement of the energy beam over the building material less energy is entered because the irradiation time is shorter, even if the energy density of the energy beam does not change. In this case, however, a change in the movement speed will lead to the solidification points associated with the individual points being changed as a result of the change in the movement speed. A change in the movement speed will therefore go hand in hand with a recalculation of the solidification times or the time periods assigned to them for the not yet solidified points from the time at which the movement speed of the energy beam is changed.

In the embodiment just described, the specified movement speed of an energy beam bundle preferably increases monotonically as the time interval decreases, and in particular, the higher the shorter the time interval, the higher the specified movement speed.

The shorter the time interval between two sites to be solidified, the greater is the mutual influence when one of the two sites is irradiated in front of the other. Since, at short time intervals, the energy introduced by the neighboring point or the output point can be utilized in the solidification, in this variant a higher speed of movement is chosen for the point to be consolidated later in order to reduce the amount of energy to be entered.

Preferably, the first scan line and the temporally subsequent second scan line are substantially parallel next to each other. This is the usual approach to behaving.

In a particular embodiment of the variant of the method, the at least one first scan line or the temporally subsequent second scan line runs along a section of the contour of an object cross section. The first and the temporally subsequent second scan line do not necessarily have to run both inside an object cross-section. The temporal proximity of the irradiation of two different locations of an object cross section is also relevant to the contour of an object cross section, where normally a scan line runs along a section of the contour of the object cross section. Accordingly, in this particular embodiment of the variant of the procedure, the temporal influence between a scan line in the interior of an object cross section and a scan line on the contour of the object cross section can also be taken into account.

In the variant of the method in the shift data record which was accessed in the first step S 1, scanning of the locations of the at least one subarea of the object cross section is preferably specified with the aid of adjoining, preferably rectangular or square, exposure areas, wherein in an exposure area during the scanning of the building material with energy radiation, an energy beam is moved in parallel scanning lines over the building material in the partial area.

By assigning exposure areas, within a subarea of the object cross section, the construction material can be scanned with scan lines of the same length, for example by aligning the scan lines all parallel to one side of a rectangular exposure area. In the event that the extent of an object section is smaller than the resulting constant scan line length, of course, this section with shorter scan line is to solidify the build-up material in this section. If the building material is scanned within an object cross-section with the aid of preferably rectangular or square exposure areas, then the method of determining time intervals between different locations to be irradiated can be carried out, in each case, for an exposure area. In particular, in the case of a rectangular or square shape of the exposure area and scan lines running parallel to one side of such an exposure area, the determination of the time intervals between locations is particularly simple in this case, for example by determining the time interval between two points on adjacent scan lines which the have substantially the same distance to a lying perpendicular to the scan lines side of the exposure area. In particular, it is also possible to introduce a new temporal assignment (eg of time segments) to the points on this scan line (a "local time") with each start of the scan of a new scan line, which also applies to the scanning of the subsequent scan line by the In the following scan line, "timestamps" which refer to the beginning of the scan of the chronologically preceding scan line are provided. In other words, the solidification times for the locations on the subsequent scan line with respect to the time zero point are set at the beginning of the scan of the preceding scan line. As an alternative or in addition to the procedure just described, time intervals can also be determined between points to be irradiated, which lie in different exposure ranges. In this way, in particular where exposure areas adjoin one another, a more homogeneous solidification can be ensured, since the influence of the temperature of a site to be solidified can be taken into account by solidification processes in the adjacent exposure area.

Preferably, a scan of the locations of the at least one subregion of the object cross section by means of a single energy beam bundle is specified in a layer data record which was accessed in the first step S1. The method can be realized in a particularly simple manner, in particular, if the solidification takes place within at least one subarea of the object cross section with only a single energy beam bundle, since then only the energy to be entered for only one energy beam bundle is to be specified.

A generative layer construction method according to the invention for producing at least one three-dimensional object, wherein in the generative layer construction method the at least one object is produced by applying a building material layer-by-layer and solidifying the building material by supplying radiant energy to locations in each layer corresponding to the cross-section of the object therein Layer by scanning these locations by means of an energy input device according to a set of energy input parameters with energy radiation, includes a computer-assisted method according to the invention for the provision of control data.

By means of the generative layer construction method according to the invention, objects can be realized very precisely.

A device according to the invention for providing control data for a generative layer building apparatus for producing a three-dimensional object, wherein the object is produced by means of the generative layer building apparatus by applying a building material layer by layer and solidifying the building material by supplying radiant energy to locations in each layer, the cross section of the object in that layer by scanning these locations with energy radiation by means of the energy input device according to a set of energy input parameters, comprises a data access unit adapted to access a number of layer data sets, one layer data set each having one data model during manufacture having selectively build-up material layer, wherein in the data model an object cross-section corresponding locations are marked, in which a solidification of the Aufbaubaum erials should take place in the appropriate shift. The device according to the invention is characterized by a time difference determination unit which is designed in at least one data model of a shift data set at at least one output point at which solidification is to take place, to determine the time interval between the time of sampling of said output point and the time of scanning of another identified location in the number of shift data sets, a shift data record modification unit, which is adapted to specify the value of an energy input parameter for the sampling of the at least one output location and / or the value of an energy input parameter for the sampling of the other identified location as a function of the size of the time interval, and a slice data set provision unit which is designed layer data sets modified by the layer data set modification unit to provide control data for the production of the three-dimensional object by means of the generative layer construction device.

The provision of layered data sets modified in the third step for the production of the three-dimensional object can also be such that the layer data record preparation unit itself integrates the modified layer data record into a control data record for the generative layer construction device. However, provision also includes forwarding one or more layer data sets to a data processing device which integrates the one or more layer data sets into a control data record, or a direct forwarding to a generative layer construction device. In particular, it is possible to dynamically provide shift data sets for object cross sections still to be produced during a production process in the generative layer construction device of this device.

A generative layer building apparatus according to the invention for producing a three-dimensional object, wherein the object is produced by the generative layer building apparatus by applying a building material layer by layer and solidifying the building material by supplying radiant energy to locations in each layer associated with the cross section of the object in that layer in that these points are scanned by means of an energy input device based on a set of energy input parameter values with energy radiation, has an inventive device for providing control data. A computer program according to the invention has program code means for carrying out all the steps of a method according to the invention for providing control data when the computer program is executed by means of a data processor, in particular a data processor cooperating with a generative layer construction device. "Interaction" means here that the data processor is either integrated into the generative layer construction device or can exchange data with it. The implementation of the inventive method for providing control data and the associated device by means of software allows easy installation on different computer systems at different locations (for example, the creator of the design of the object or the operator of the generative layer building apparatus).

In a computer-readable storage device according to the invention, the computer program according to the invention is stored. The storage device may be a portable storage medium, but in particular may also be a memory present in a generative layer construction device or the energy input device.

Further features and advantages of the invention will become apparent from the description of embodiments with reference to the accompanying drawings.

1 shows a schematic, partially sectional view of an exemplary apparatus for generatively producing a three-dimensional object according to an embodiment of the invention,

2 schematically shows the procedure when an object cross-section to be solidified is scanned with the aid of exposure areas,

3a and 3b each show a schematic plan view of a region of an object cross-section to illustrate a possible procedure according to the invention, W

20

FIG. 4 shows a schematic plan view of a region of an object cross-section to illustrate a further possible procedure according to FIG

Invention,

5 illustrates the flow of a method for providing control data, and

Fig. 6 shows the schematic structure of an apparatus for providing control data.

For a description of the invention, a generative layer construction device according to the invention will first be described below, using the example of a laser sintering melting device, with reference to FIG. 1.

To build up 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, an upwardly open building container 5 with a container wall 6 is arranged. A working plane 7 is defined by the upper opening of the construction container 5, wherein the area of the working plane 7 which lies within the opening and which can be used to construct the object 2 is referred to as construction field 8.

In the building container 5 a movable in a vertical direction V carrier 10 is arranged, on which a base plate 11 is mounted, which closes the container 5 down and thus forms its bottom. The base plate 11 may be a plate formed separately from the carrier 10, which is fixed to the carrier 10, or it may be formed integrally with the carrier 10. Depending on the powder and process used, a building platform 12 can still be mounted on the base plate 11 as a construction base on which the object 2 is built up. The object 2 can also be built on the base plate 11 itself, which then serves as a construction document. In Fig. 1 is to be formed in the container 5 on the building platform 12 Object 2 below the working level 7 in an intermediate state shown with several solidified layers, surrounded by unresolved remained building material 13th

The laser sintering or melting apparatus 1 further comprises a reservoir 14 for a building material 15, in this example an electromagnetic radiation solidifiable powder, and a coater 16 movable in a horizontal direction H for applying the building material 15 within the construction field 8 the process chamber 3 a heating device, eg a radiant heater 17 may be arranged, which serves to heat the applied building material. As radiant heater 17, for example, an infrared radiator can be provided.

The exemplary generative layer building apparatus 1 further comprises an exposure device 20 with a laser 21, which generates a laser beam 22, which is deflected by a deflection device 23 and 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 is focused on the working level 7.

Furthermore, the laser sintering device 1 includes a control device 29, via which the individual components of the device 1 are controlled in a coordinated manner for carrying out the building process. Alternatively, the control device may also be mounted partially or completely outside the device. The controller may include a CPU whose operation is controlled by a computer program (software). The computer program can be stored separately from the device on a storage medium from which it can be loaded (for example via a network) into the 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 actuated to apply a new powder layer and the deflection device 23 and optionally also the laser 21 and / or the focusing device 24 are activated. controlled to solidify the respective layer at the locations corresponding to the respective object by means of the laser by scanning these locations with the laser.

For example, in laser sintering or laser melting, an exposure apparatus may include one or more gas or solid state lasers, or any other type of laser, such as a laser. Laser diodes, in particular Vertical Cavity Surface Emitting Lasers (VCSELs) or Vertical External Cavity Surface Emitting Lasers (VECSELs), or a line of these lasers. The specific structure of a laser sintering or melting apparatus shown in Fig. 1 is therefore exemplary only for the present invention and can of course be modified, especially when using a different exposure device than the one shown. To make it clear that the shape of the radiation incident surface on the building material may not necessarily be approximately punctiform, but also flat, the term "beam" is often used in the following synonymous with "beam".

All statements made in the further course apply not only to laser sintering or melting devices, but also to other types of generative layer construction devices in which heat energy in the form of radiation is introduced into the construction material.

In the generative layer construction device just described by way of example, a production process proceeds in such a way that the control unit 29 processes a control data record (often also referred to as a control instruction set). The procedure according to the invention will be described below by way of example with reference to FIGS. 2 to 6.

As shown in FIG. 6, a generative layer construction control data providing apparatus 100 includes a data access unit 101, a time difference detection unit 102, a layer data set modification unit 103, and a layer data record preparation unit 104. The operation of the control data providing apparatus 100 will be described with reference to FIG. 5. Figs. 2 to 4 serve to further illustrate. In the generative layer construction control data providing apparatus 100 shown in FIG. 6, first, the data access unit 101 accesses a number of layer data sets, each of which has a data model of a building material layer to be selectively solidified during fabrication. In the process sequence shown in FIG. 5, this is step S1. In each data model, locations of the layer to which building material is to be solidified are marked corresponding to an object cross-section. For a better illustration of the procedure, it is assumed here by way of example that in the data model it is indicated how an energy beam (eg a laser beam) is to be moved over the object cross-section in several temporally successive scan lines in order to solidify it.

In a step S2 shown in FIG. 5, in at least one data model of a shift data set at at least one output point PI at which solidification is to take place, the time difference between the time of sampling of this output point PI and the time of the Scanning another location Nl, which is identified in the data model as a point to be solidified determined. The exact procedure is explained by way of example in FIG. 3a.

3a shows a plan view of a partial region of an object cross-section to be solidified, specifically two adjacent scan lines 54a and 54b, along which the energy beam, also referred to below as laser beam, is to be moved during scanning of the building material. It is assumed here that in the data model not only the time order in which the laser beam is to be moved over the building material is specified but also the times at which the laser beam is to be solidified at a predetermined time scale are also specified Building material layer impinges on the building material. In FIG. 3 a, such an assignment to a time scale provides, by way of example, such that different time intervals 154 are assigned to the different locations on a scan line. The direction in which the scan lines 54a and 54b are traversed is indicated by arrows in FIG. 3a. The scan line 54a is thus initially passed through at its upper end in the drawing representation. Associated with this region of the scan line is a first time segment 154, which is illustrated by the numeral "1" to the right of the scan line 54a. As the scanning line is advanced, further portions on the scan line are assigned a second to fifteenth period (again represented by the numerals "2" to "15") so that the scan line 54a is completely scanned after fifteen time periods.

As can be seen in FIG. 3 a, a time interval 154 is assigned to a plurality of locations on a scan line, and in each case to the locations between horizontal lines 154 h, shown dashed in FIG. 3 a. The amount of time that passes through a period 154 may be selected to correspond to the actual amount of time required for the laser beam to pass through the corresponding portion of the scan line during the manufacturing process of the object. Preferably, the time periods 154 are chosen so that the time periods associated with them are all the same. This simplifies the procedure.

It can be seen in FIG. 3a that the scan line 54b is also allocated time segments 154, namely a seventeenth to thirty-first period of time (the numbering of the time segments should indicate the chronological order in which they are run). It is therefore obvious that the scan line 54b should be timed after the scan line 54a. It can be seen at the arrowhead of the scan line 54a a dashed arcuate arrow 154s, which illustrates an offset of the laser beam without exposure, so a jump point. In addition to the discontinuity 154s, the numeral "2" indicates that two time segments are required for the offset of the laser beam. Therefore, the exposure of the scan line 54b also starts at the seventeenth time period.

If in a data model either no information about the time sequence in which the locations of an object cross section are to be solidified is contained or if no time scale for the scanning of the locations of the object cross section is specified, then If the information is added to the data record before the method is carried out or the device 100 itself, in particular the time difference determination unit 102, adds this information to the data model of a shift data record.

In the example of FIG. 3a, the time difference determination unit 102 determines the time difference 155 between a section on the first scan line 54a and a section on the scan line 54b. In the example, an exit point PI is marked on the scan line 54a, which, together with other locations, is assigned the eleventh time period for an exposure, and on the second scan line 54b a location N1 is marked, which, together with other locations, the twenty-first time interval for an exposure is assigned. The time difference determination unit 102 now determines, for the locations PI and Nl, a time difference of ten sections, which lies between the exposures of the two locations. Such a temporal difference is preferably determined for all time segments which lie opposite one another on the two mutually parallel scan lines 54a and 54b. The corresponding results are shown as numbers in the middle between both scan lines (reference numeral 155), the numerical value indicating the time difference between the exposure times on the first scan line 54a and the second scan line 54b.

In a third step S3 shown in FIG. 5, the layer data set modification unit 103 now either changes an energy input parameter for the scanning of the first scan line 54a and / or the second scan line 54b. The extent of the modification of the energy input parameter (s) depends on the value of the time difference 155. As can be seen in Fig. 3a, the time difference is very small, especially at the jump point 154s. There, therefore, the areas exposed in the fifteenth period on the scan line 54a and the areas exposed in the seventeenth period are exposed on the scan line 54b immediately after one another. Accordingly, the layer data set modification unit in the data model will specify that either the originally intended energy density of the laser beam in scanning the scan line 54a and / or the energy density (beam energy per unit area) is lowered with the scanning of the scan line 54b with the laser beam since in scanning the places in the seventeenth period still very much residual heat is present, the sampling along the first scan line 54a in the fifteenth period. On the other hand, one recognizes that z. For example, the time difference 155 between the first time period and the thirty-first time period is thirty time periods, so that only a small or negligible amount of residual energy resulting from the solidification in the first time period is present in the thirty-first time period upon solidification. At the corresponding points of the first scan line 54a and / or the second scan line 54b, therefore, the slice data modification unit 103 will lower the energy density only slightly or not at all in relation to the originally intended energy density.

The originally intended energy density of the energy beam bundle ("standard energy density") is generally based on empirical values for the generative layer building apparatus used for production and a building material used. Also with regard to the shape and size of the objects to be produced, the person skilled in the art knows in advance which energy density is to be selected preferably at a location of an object cross section. If necessary, values to be used for the standard energy density can also be determined during preliminary tests.

A change in the energy density of the energy beam bundle can be accomplished, for example, by reducing the power of the laser source or electron beam source, by changing the control of the radiation energy source, for example a change in the laser pulse width in a pulsed laser, etc.

Finally, in a step S4 shown in FIG. 5, the layer data record providing unit 104 finally provides the layer data set modified in step S3 for production by means of the generative layer building apparatus, for example for integration into a control instruction set thereof.

Hereinafter, modifications of the procedure just described will be described. Fig. 3a shows as an example the ideal case in which two scan lines are the same length and parallel to each other and exactly opposite each other. This ideal case is when a rectangular or square object cross-section is solidified and the scan lines are parallel to one of the sides of the rectangle or square. Furthermore, this ideal case is important for hardening strategies in which a plurality of exposure areas are assigned to an object cross-section to be solidified or at least a sub-area thereof. Such a procedure is schematically illustrated in FIG. 2, which shows by way of example a rectangular object cross section 50. The object cross section 50 in FIG. 2 consists of an inner region 52 and a contour line 51. While the contour line 51 is usually solidified by traversing the contour of the object cross section by means of a solidification beam, the inner region 52 exposure region for the exposure region is scanned. In Fig. 2, only two exposure areas 53 are shown, which have a rectangular shape in the example. The entire inner area 52 can be covered with such exposure areas 53, even if, for reasons of clarity, only two exposure areas 53 are shown.

To solidify the build material within an exposure area 53, the energy beam (e.g., a laser beam) is moved across the build material in scan lines 54 substantially parallel to each other. For example, in FIG. 2, each of the two exposure areas 53 would be scan-scanned line by line from left to right, with two adjacent scan lines respectively being traversed in opposite directions. For the sake of completeness, it is added that if an exposure area 53 projects beyond the interior area 52 at its edge, of course only the building material in the exposure area 53, which is also inside the interior area 52, is scanned and solidified.

It will be appreciated that in the consolidation strategy illustrated in FIG. 2, the example case shown in FIG. 3a is the rule. By means of the procedure according to the invention, it is therefore possible to ensure, especially in the course of the procedure according to the exposure strategy shown in FIG. 2, that different temperature conditions before solidification, which can be present at different points of a scan line, can be compensated. In particular, you can W

28

Overheating operations near the discontinuities of the laser beam at the respective transition to the next scan line can be prevented.

3b illustrates the procedure when scan lines have different lengths and are not exactly opposite each other. Such a constellation can occur in the case of complex, non-rectangular object cross sections or in cases in which, in FIG. 2, an exposure area 53 projects beyond a non-rectangular object cross section.

The procedure in Fig. 3b is similar to that of Fig. 3a. Again, individual sections of a scan line are assigned time sections 154. In the example of FIG. 3b, the scan line 56a is scanned in front of the scan line 56b and this in front of the scan line 56c. Accordingly, analogously to the procedure in FIG. 3 a, the scan line 56 a is assigned the first to the tenth time segment. In the transition from the scan line 56a to the scan line 56b, the solidification beam must be moved over a longer distance than in Fig. 3a. Therefore, three time periods are required for the jump, so that the scan line 56b is assigned the thirteenth to twentieth time segments and, after another transition jump to the scan line 56c, these are assigned to the twenty-second to twenty-fifth time segments. As can be seen on the basis of the time differences 155 shown in FIG. 3b, these are respectively determined at those points at which areas of different scan lines lie opposite one another, ie points at which a solder built on a scan line intersects an adjacent scan line.

4 shows an example with eight scan lines 57a, 57b, 57c, 57d, 57e, 57f, 57g and 57h. The procedure in the example of Fig. 4 is analogous to that in Figs. 3a and 3b. With reference to FIG. 4, however, a time scale can be entered which is assigned to the solidification times of the individual points on the scan lines. It can be seen with reference to FIG. 4 that a general time scale does not necessarily have to be introduced, on which each time point to be solidified of an object cross-section is assigned a time or each point is assigned to a time interval. Rather, it can be seen in FIG. 4 that it is also possible to introduce a local time scale for two adjacent scan lines, with respect to which For example, the time difference determination unit 102 assigns time sections 154 to the individual locations on the scan lines. For example, the locations of the scan line 57b are each assigned two different time periods: a time interval 157a with respect to the temporally preceding scan line 57a and a time interval 157c with respect to the temporally subsequent scan line 57c. Thus, in each case two adjacent scan lines are assigned a time scale. Beside the scan line 57b, those time portions 157a relating to the preceding scan line 57a are shown on the side facing the scan line 57a, and those time portions 157c relating to the scan line 57c are shown on the side facing the scan line 57c. The rest of the scan lines are analogous.

FIG. 4 shows that time differences are respectively determined only between locations on mutually adjacent scan lines. Depending on how large the distance between the individual scan lines, but could also be an influence of the next but one scan line available. Accordingly, it would be possible to determine not only the time interval of the fourth time portion of the scan line 57a to the twenty-eighth time period on the scan line 57b but also the time interval between the fourth time period on the scan line 57a and the sixteenth time period on the scan line 57c. In other words, one could make the energy density of the radiation to be incident on the locations assigned to the fourth time segment on the scan line 57a dependent on two different time differences. Obviously, the time difference to the scan line 57b would be considered more strongly, for example, by a different weighting factor than the time difference to the locations of the sixteenth time segment on the scan line 57c.

Furthermore, it is of course also possible to incorporate several time differences between a point on a first scan line and a plurality of points on another second scan line in the definition of the energy input on the first scan line. For example, to calculate the energy input at the locations in the fourth time period on the scan line 57a, one could include the time differences at the twenty-sixth, twenty-seventh, twenty-eighth, and twenty-ninth time periods on the scan line 57b. The procedure according to the invention is not limited to scanning lines lying parallel to one another. For example, there may be an influence on the solidification behavior in the upper left corner of the inner region 52 in FIG. 2 if the contour 51 was scanned shortly before the scanning of the scan line 54 on the far left and therefore both scanning processes are temporally close to each other. In such a case, it is advantageous to let the time difference between the scanning of points of the scan line 54 at the far left and the scanning of the contour line in the upper left corner of the cross section 50 in FIG. 2 flow into the energy to be entered at the locations of the scan line 54 (assuming that it is solidified after contour line 51).

Furthermore, time differences do not necessarily have to be determined between locations within an object's cross-section to determine the energy to be entered. In Fig. 1, the object to be produced 2 is shown in an intermediate state in which already solidified object cross-sections can be seen. In FIG. 1, when the uppermost object cross-section is solidified, it may happen that the immediately below object cross-section, which has just been solidified, still contains a great deal of heat energy, which is emitted to the uppermost object cross-section to be solidified. Accordingly, it may be useful to determine a time difference between the solidification of a location in the uppermost layer and a location in an underlying layer, for example, the immediately underlying location in the immediately underlying layer and on this basis the energy to be entered in the top layer. Depending on the building material and the type of layering device, there could also be an influence of places in layers below the layer immediately below. Accordingly, it would be possible to consider not only the time difference to a location in the immediately underlying layer, but also one or more temporal distances to locations in one or more further layers below the immediately underlying layer.

In the examples of FIGS. 3 and 4, a plurality of sites to be consolidated were assigned one and the same time period in each case. Of course, one could also Assigning le to an individual period of time, however, would greatly increase the data volume of the data model of a layer. Likewise, the procedure shown can be modified if the energy density of the radiation / beam is not changed to change the energy input, but the scanning speed, ie the speed with which the beam is moved over the building material. In this case, the assignment of points to be scanned at sampling times / periods must be done dynamically because with changing scanning speed, for example an increase in the scanning speed, within the time period of a standard time segment, as in each case between two horizontal lines in FIGS. 3 and 4 154h, the number of locations to be assigned to such a period increases on a scan line. In other words, in the method, when the scanning speed is changed, after the change of the scanning speed, a reassignment of time periods to scanned positions and a new determination of time intervals should be made for the positions to be scanned.

It should be mentioned that of course not all periods have to be the same length. However, an identical time interval or standard time period is advantageous, since in the calculation of time differences, the sampling time required for a standard time period can be regarded as a time unit and the calculation of the time differences can be used as the basis for the explanation of FIG 3 and 4 happened.

Finally, it should be mentioned that a device 100 according to the invention for providing control data for a generative layer construction device can be realized not only by software components but also solely by hardware components or mixtures of hardware and software. In particular, interfaces mentioned in the present application do not necessarily have to be designed as hardware components, but can also be realized as software modules, for example, if the data fed in or output therefrom can be taken over by other components already realized on the same device or to a user other components only have to be transferred by software. Similarly, the interfaces could be hardware and software components, such as a standard hardware interface specifically 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.

Claims

A computer-aided method for providing control data to a generative layer building apparatus for producing a three-dimensional object, wherein the object is manufactured by the generative layer building apparatus by applying a building material layer by layer and solidifying the building material by supplying radiant energy to locations in each layer belonging to the Are cross-sectioned of the object in that layer by scanning these locations with energy radiation by means of an energy input device based on a set of energy input parameter values,

wherein in a first step (S1) a number of layer data sets are accessed, wherein a layer data set each has a data model of a build material layer to be selectively solidified during production and in the data model an object cross section corresponding locations are identified, at which a solidification of the building material (15 ) should take place in the appropriate layer

characterized in that in a second step (S2) in at least one data model of a layer data set at at least one output point (PI) at which a solidification is to take place, the time interval (155) between the time (154) of sampling this output point (PI ) and the time (154) of scanning another designated location (Nl) in the number of shift records, preferably another designated location (Nl) in the shift record,

in a third step (S3) the number of layer data records is modified such that the value of an energy input parameter for the sampling of the at least one output location (PI) and / or the value of an energy input parameter for the sampling of the other identified location (N1) is dependent on the size of their time interval is specified and in a fourth step (S4), the layer data sets modified in the third step are provided as control data for the production of the three-dimensional object by means of the generative layer construction device.

2. Method according to claim 1, wherein in the third step (S3) the value of an energy input parameter for the sampling of the at least one output point (PI) and / or the value of an energy input parameter for the sampling of the other marked point (N1) in dependence on the Size of the spatial distance between these and / or depending on the nature and condition of the building material to be specified at one of these locations.

3. The method according to any one of the preceding claims, wherein the time within which the cross sections of the object in the layers associated points are scanned with energy radiation is divided into, preferably equal, time segments and a time interval between the respective periods associated with the sites is determined.

4. The method of claim 3, wherein, in particular when the other designated point (Nl) is assigned a later period than the at least one output point (PI), in the third step (S3) the value of an energy input parameter for the scanning of the other marked point (Nl) is determined as a function of the value of an energy input parameter for the sampling of the at least one output point (PI) and / or

in particular if the at least one output point (PI) is assigned a later time interval than the other marked point (N1), in the third step (S3) the value of an energy input parameter for the sampling of the at least one output point (PI) as a function of the value Energieeintragsparameters for scanning the other designated location (N l) is determined.

5. Computer-aided method according to one of the preceding claims, wherein in the first step (S1), a slice data set is accessed in which a sampling of the locations of at least one subregion of the object cross section is specified with at least one energy beam bundle by specifying temporally successive scan lines for the movement of the at least one energy beam bundle,

in the second step (S2) for at least one first scan line, preferably all scan lines, at at least two different output locations (PI, P2) on this first scan line the time interval (155) between the time (154) of sampling this output location (PI, P2) and the time (154) of the sampling of a neighboring location (N l, N2) of this location is determined on a temporally subsequent second scan line,

in the third step (S3), the shift data record is modified in such a way that different values of an energy input parameter for the sampling of the at least two different output locations (PI, P2) and / or different values of an energy input parameter for the sampling of the respective neighbor locations are used for different time intervals (Nl, N2), and

in the fourth step (S4), the layer data record modified in the third step is provided for controlling the production of the three-dimensional object by means of the generative layer construction device.

6. The method of claim 5, wherein the respective neighboring point (Nl, N2) is selected on the temporally subsequent second scan line within a range of a predetermined dimension around that point (PP) on the second scan line on which a at the output Place (PI, P2) plotted on the first scan line plots the second consecutive scan line.

A method according to claim 6, wherein the predetermined dimension is 40%, preferably 20%, more preferably 10%, of the distance between the exit point and the point (PP) on the second scan line, at which point at the exit point (PI , P2) Lot built on the first scan line intersects the temporally subsequent second scan line.

8. The method according to any one of claims 5 to 7, wherein for different time intervals (155) specify different amounts of radiation energy to be entered per unit area at the at least two different output locations (PI, P2) and / or the respective neighboring locations (Nl, N2) become.

9. The method of claim 8, wherein the specified amount of radiation energy to be entered per unit area monotonically with the determined time intervals (155) falls, in particular the smaller the specified, the shorter the time interval is.

10. The method according to any one of claims 5 to 9, wherein for different time intervals (155) different movement speeds of an energy beam bundle at the at least two different output points (PI, P2) and / or the respective neighboring sites (N l, N2) specified become.

11. The method of claim 10, wherein the specified movement speed of an energy beam monotonically increases with decreasing time interval, in particular the higher the specified, the shorter the time interval is.

12. The method according to any one of claims 5 to 11, wherein the at least one first scan line or the temporally subsequent second scan line extends along a portion of the contour of an object cross-section.

13. Method according to one of claims 5 to 12, in which in the slice data set accessed in the first step (S1), a scanning of the locations of the at least one partial area of the object cross section is specified with the aid of adjacent, preferably rectangular or square, exposure areas wherein, in an exposure area in the scanning of the building material with energy radiation, an energy beam is moved in parallel scanning lines over the building material in the partial area.

14. A generative layer construction method for producing at least one three-dimensional object, wherein in the generative layer construction method the object is produced by the generative layer construction apparatus by applying a building material layer by layer and solidifying the building material by supplying radiant energy to locations in each layer corresponding to the cross section of the object in this layer are assigned by scanning these locations by means of an energy input device based on a set of energy input parameter values with energy radiation, wherein the generative layer construction method includes a method according to one of claims 1 to 13.

15. A device for providing control data for a generative layer building apparatus for producing a three-dimensional object, wherein the object is produced by the generative layer building apparatus by applying a building material layer by layer and solidifying the building material by supplying radiant energy to locations in each layer that the cross section of the object in that layer are scanned by means of an energy input device based on a set of energy input parameter values with energy radiation,

wherein the device for providing control data comprises:

a data access unit (101) which is designed to access a number of layer data sets, wherein a layer data set each has a data model of a build material layer to be selectively solidified during production, wherein in the data model an area corresponding to an object cross section is identified by which solidification of the building material ( 15) in the appropriate layer,

characterized by a time difference determination unit (102) which is adapted to at least one output point (PI) at least one data model of a shift data set, at which a solidification takes place, the time interval between the time of sampling this output point (PI) and the Determine the time of sampling of another designated location (Nl) in the number of shift records

a layer data set modification unit (103) which is designed to determine the value of an energy input parameter for the sampling of the at least one output point (PI) and / or the value of an energy input parameter for the sampling of the other specified position (Nl) depending on the size of the time interval to specify, and

a slice data set providing unit (104) configured to provide slice records modified by the slice data set modification unit (103) as control data for producing the three-dimensional object by the generative slice building apparatus.

16. Generative layer building apparatus for producing a three-dimensional object, wherein the object is produced by the generative layer building apparatus by applying a building material layer by layer and solidifying the building material by supplying radiant energy to locations in each layer associated with the cross section of the object in that layer in that these locations are scanned by means of an energy input device based on a set of energy input parameter values with energy radiation, wherein the generative layer construction device comprises an apparatus according to claim 15.

A computer program comprising program code means for carrying out all the steps of a method according to one of claims 1 to 13, when the computer program is executed by means of a data processor, in particular a data processor interacting with a generative layer construction device.

18. A computer readable storage device on which the computer program according to claim 17 is stored.