WO2018172079A1

WO2018172079A1 - Overlap optimization

Info

Publication number: WO2018172079A1
Application number: PCT/EP2018/055616
Authority: WO
Inventors: Martin Schade
Original assignee: Eos Gmbh Electro Optical Systems
Priority date: 2017-03-24
Filing date: 2018-03-07
Publication date: 2018-09-27
Also published as: DE102017205051A1

Abstract

The invention relates to a computer-aided method for generating a control dataset for a generative layer construction device, wherein, in the latter, an input device (20) is configured to direct a plurality of beams (22) onto different regions of an applied layer. In a first step (S1), access is made to at least two layer data sets which have data models of a corresponding number of structural material layers to be solidified selectively during the production. In a second step (S2), a plurality of partial cross-sections (31, 32, 41, 42) adjoining one another are defined in a layer dataset. The partial cross-sections (31, 32, 41, 42) are defined such that a boundary area (35, 45) differs in the shape and/or position thereof in the layer plane with respect to the shape and/or position of a boundary area (35, 45) in a layer dataset assigned to the immediately preceding or the immediately following layer. In a third step (S3), the layer dataset modified in the second step (S2) is provided as a control dataset for the generative layer construction device.

Description

Überlappoptimierung

The invention relates to a computer-assisted method for generating a control data record for a generative layer building apparatus and to a device suitable for carrying out the method.

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 may, for example, be brought about by supplying heat energy to the building material by irradiating it with electromagnetic radiation or particle radiation (eg laser sintering (SLS) 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.

Especially in additive manufacturing, it is important not only to produce the objects with high precision, but also within a short production time. The production time can be reduced if, to solidify the one or more object cross-sections in a layer corresponding points several energy beams, eg. As laser beams are used at the same time. WO 2016/110440 A1 describes a corresponding device in which different laser beams are assigned to different areas of a layer, wherein there are areas in which a plurality of beams can act on the building material, ie areas to which not only one laser beam but several laser beams are directed can be.

FIG. 11 illustrates this procedure on the basis of a construction field on which four laser beams can act simultaneously. In the construction field 8 in FIG. 11, those regions in which only one of the four laser beams can be used during solidification are designated AI to A4. Areas in which two laser beams can be used together for solidification are indicated by the letter "B", with the numbers following the letters denoting which of the four laser beams (numbered 1 to 4) are used. Finally, there is a central area C1234, where all four laser beams can be used together to consolidate one or more cross sections in this area.

WO 2016/110440 A1 deals with the problem that it is necessary to coordinate which of the laser beams that can be used in a common area is directed to a specific location in this area. The coordination can in particular be such that a laser beam, in the subregion only a few places within a

Layer to be solidified, can be used in an adjacent subregion in which many points must be solidified.

The inventors have found that in the boundary region of the action zones of different laser beams, for example in the region B12 in FIG. 11, at the boundary line G between the region B121, which is solidified by the laser beam 1, and the region B122, that from the laser beam 2 is solidified, the Aufschmelzverhalten or solidification behavior of the building material is slightly different than in other areas. In particular, the inventors were able to determine that slight inhomogeneities occur at the boundary line, which lead to mechanical weak points, especially when accumulated over a larger volume can. Although the use of several lasers can significantly reduce the production time, it may be necessary to accept losses in the quality of the manufactured objects. In view of the problem just described, 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 achieved by a computer-aided method according to claim 1, a generative layer construction method according to claim 13, a device for computer-aided generation of a control data set according to claim 14 and a computer program according to claim 15. Further developments of the invention are claimed in the dependent claims inventive method be further developed by below or in the dependent claims executed features of the devices according to the invention and vice versa. Furthermore, the features described in connection with a device can also be used to develop another device according to the invention, even if this is not explicitly stated. A computer-assisted method according to the invention for generating a control data record for a generative layer building apparatus for producing a three-dimensional object by means of the same, the production comprising the steps:

Building the object layer by layer, and

Controlled directing of radiation of at least one radiation source by means of an input device on an object cross-section corresponding areas of a layer of a building material,

wherein the insertion means is adapted to direct a plurality of beams to different regions of an applied layer, each of the beams, where it strikes the layer, acting on the building material, in particular so as to solidify it, indicates:

a first step of accessing at least two layer data sets which have data models of a corresponding number of build material layers to be selectively solidified during fabrication, wherein in a data model an object cross-section is identified corresponding locations at which solidification of the build material is to occur;

wherein it is characterized in a data model which of the plurality of beams is intended to solidify the building material at which of the locations corresponding to the respective object cross-section,

characterized in that in a second step in a layer data set a plurality of adjoining partial cross sections, ie to be solidified subregions of an object cross section are determined, is determined for each of the partial cross sections, with which beam to consolidate the bodies in this partial cross section,

wherein the partial cross-sections are determined such that a boundary region, ie an area lying at the boundary between different partial cross-sections, in its shape and / or position in the layer plane with respect to the shape and / or position of a boundary region in one of the immediately preceding or immediately following Layer assigned shift data set is different and

in a third step, the layer data record modified in the second step is provided as a control data record for the generative layer building apparatus.

In this case, the radiation source may be, for example, a laser or an electron beam source, but it would also be conceivable for a device for 3D printing which generates a binder beam or a UV light source in stereolithography. The term "beam" is intended to express that not only rays are meant that have a round cross section when hitting the building material, but also rays that z. B. have a linear cross-section or even radiation, which is registered at the same time in a larger area of the building material (ie area). In this case, a data record which contains a data model of a build-up material layer to be consolidated at the locations of an object cross-section during the production process is regarded as a shift data record. In particular, such a data model has a two-dimensional representation of the object cross-section to be consolidated in one layer by means of one or more beams. In addition, it is specified which of the plurality of beam bundles is to be directed to a location of the object cross section. In this case, different locations in an object cross-section are usually solidified by different beam bundles. In addition, it is of course also possible that a certain point of the object cross-section is solidified by directing multiple beams to this point. In the layer data set can, but need not, even more information regarding the production of the object cross section may be included, for. B. the layer thickness, the diameter of an incident on the building material beam, etc.

If access to at least two shift records is mentioned, this means that a shift record is read from a memory or the data corresponding to the shift record is received via a network. The two shift records do not necessarily have to be read together (ie simultaneously). It is also possible that there is a greater time interval between the access operations on the two shift records, for example, one of the two shift records was read in at an earlier time.

The decomposition into partial cross sections takes place in such a way that all points within a partial cross section are to be solidified with the same bundle of rays. With the procedure according to the invention, it is possible, for example, to prevent inhomogeneities in the solidification of the building material, which can occur at the boundaries between the areas of action of different solidification beam bundles, in a manufactured object in larger coherent areas. Thereby, the mechanical parameters (eg the elongation at break) of the manufactured object can be improved. Also, for example, a bead on the object surface, as through Limits between the areas of action, which may occur in several layers, can be avoided. The boundary between the action areas is referred to as the "boundary area". Normally it can be assumed that the border between two areas is a borderline. Depending on the construction material used and the desired properties of the object to be produced, however, it may be appropriate to allow the two areas of action, where they adjoin one another, to overlap upon solidification or to leave a distance between the two areas of action. For this reason, in the present application, the term "boundary area" was chosen. In addition, at sufficiently high magnification, any real line can be considered an area.

The method is preferably carried out in such a way that the boundary regions in at least two successive layers do not completely cover one another, that is to say not 100%, and even more preferably cover each other at 0%, ie not at all. As a result, for example, objects with particularly good surfaces or properties can be produced, although the production time is low due to the use of a plurality of beams for solidifying. The percentages of overlap refer to overlapping a percentage of the area of one of the boundary areas with the other. The overlapping areas need not match in shape and / or size even with complete coverage. For example, suppose that in a layer, a boundary region has a linear shape, in particular the shape of a straight line

Line, so should in the overlying layer also has a linear boundary area of the same shape and line orientation, both border areas by at least 50%, preferably by 100%, more preferably by 120% of the line width in a direction perpendicular to the line shape against each other be postponed.

More preferably, the method is carried out such that the shape and / or position of the boundary region in the layer plane are set so that they repeat at the earliest after n layers in the manufacturing process, where n is a natural number greater than one. By such a procedure, for example, the occurrence of mechanical weak points in the object can be effectively limited. Even more preferably, the shape and / or position of the boundary region in the layer plane are set so that they repeat in the manufacturing process at the latest after m layers, where m is a natural number greater than or equal to n. As a result, for example, the definition of the shape or position of a boundary region can be simplified, since these do not have to be different in all layers.

In particular, the shape and / or position of the boundary region in the layer plane can be set so that they change during the manufacturing process in the construction direction according to a first periodic function, in particular a sine function, triangular function or rectangular function. This means, in particular, that the shape and / or position over a plurality of layers are so different that the changes can be described by means of a periodic function as a function of the layer number, with higher layer numbers being assigned later to layers to be consolidated in the production process in the manufacturing process earlier to be consolidated layers. If, for example, the position of a boundary region, the shape of which does not change, change in the construction direction according to a sinusoidal function in the manufacturing process, then the location of the boundary region in the layer planes would be described by a sinusoidal function at a section through the layer stack at a suitable location or (at discrete Locations) can at least approximate.

Due to the described periodic variation of the position and / or shape of a boundary region, the mechanical strength of a manufactured object can be particularly high. The reason is that (for example in the case of a triangular function), a toothing of the partial cross sections solidified with different beam bundles occurs in different layers.

In particular, the shape and / or position of the boundary region in the layer plane can be set so that they additionally change in the construction direction in the construction direction according to a second periodic function, which is superimposed on the first periodic function and preferably has a shorter period than the first periodic function , Thereby In spite of the gearing effect just described, care can be taken to avoid excessive accumulation of boundary regions (in particular with regard to beads on the object surface).

In a variant of the method according to the invention, this is also applied to boundary regions which lie in the contour of an object cross section and delimit therefrom two sections of the contour region which are solidified by different solidification beam bundles. The sections of the contour area are also considered as partial cross-sections of an object cross section, which is permissible, since normally the contour area is run over with a beam of finite diameter for solidification and thus can be regarded as a two-dimensional area. The same applies to the point at which the two sections adjoin one another, which can likewise be regarded as a flat area and is referred to as a border area. Since inhomogeneities in the object condition can easily be perceived at the object surface, the variant of the method according to the invention is particularly suitable for objects which require optically exact surfaces, for example objects of aesthetic value.

Furthermore, the shape and / or position of the boundary region in the layer plane can be set such that in at least one layer the position of the boundary region is twisted relative to another rotation axis perpendicular to the layer planes, preferably by an angle is greater than or equal to 5 °, more preferably an angle greater than or equal to 10 °, even more preferably an angle greater than or equal to 20 °, provided that the shape of the boundary region in the two layers is substantially equal. With such a procedure, the position and / or shape of a boundary region can be varied in a particularly effective and simple manner, since (complete) overlapping is avoided in a particularly effective manner by rotations. In particular, the rotation according to the already mentioned second periodic function can take place over a plurality of layers. In a variant of the method according to the invention, the shape and / or position of the boundary region in the layer plane can be set such that they change in the layers in the direction of construction according to a random function. By such a random variation of the shape and / or position of the boundary region in the layer plane, it is possible to avoid cumulation of the boundary regions in different layers in a particularly thorough manner.

In particular, the shape and / or position of the boundary region in the layer plane can also be set so that they change according to a function resulting from a superimposition of the first and / or second periodic function with a random function. By "overlay with a random function" it is meant that the values of the first or second periodic functions are changed randomly, similarly to e.g. B. a sine function, which is not an exact sine function, but is "noisy". Instead of using a random function, it is also possible to use a function which does not lead to a randomly determined position and / or shape of border regions, but to the fact that the position and / or shape of boundary regions repeat in a pattern that is the case Viewing is not readily apparent. Such a procedure is particularly suitable in connection with boundary areas present on the surface (or in the contour) of objects.

In a variant of the method according to the invention, the change in the shape and / or position of the boundary region from layer to layer can take place depending on whether a boundary region is located in a pre-determined section of an object to be produced. This can be used, for example, to meet different requirements for different sections of an object to be produced. For example, in a subsection of the object located near the surface, the position and / or shape of a border region can be varied more from layer to layer than in a section remote from the surface, in order to meet the high demands on the optical quality of the surface. to meet. In particular, the method can be carried out only for one or more predetermined subsections of an object to be produced.

In an advantageous modification of the method according to the invention, in the second step for at least a section of at least one object cross-section as a function of specifications for a quality of the section and / or a production time of the object, it is determined with which number of beam bundles the building material is to be solidified within this section. Thus, the production of the object can additionally be optimized with regard to production time and quality via the number of beams used for solidifying.

A generative layer construction method according to the invention for producing a three-dimensional object by means of a generative layer construction apparatus, the production comprising the steps:

Structure of the object layer by layer,

controlled irradiation of radiation of at least one radiation source by means of an entry device on an object cross section corresponding areas of a layer of a building material,

wherein the insertion means is adapted to direct a plurality of beams simultaneously to different regions of the applied layer, each of the beams acting on the building material where it impinges on the layer, in particular so that it is solidified,

uses a control data set generated by a method according to the invention for the production. Thus, a manufacturing process with respect to production time and quality of an object to be produced can be optimized, for example by the inventive method for generating a control data set is carried out before the start of the manufacturing process, in particular before the application of the first building material layer and the flow of the manufacturing process is controlled by a control instruction set, which contains the control data set provided by the method according to the invention for generating a control data record, A generative layer construction device according to the invention has a control device which controls a production process of an object using a control data record generated by a method according to the invention.

A device according to the invention for computer-aided generation of a control data set for a generative layer building apparatus for producing a three-dimensional object by means of the same, the production comprising the steps:

Structure of the object layer by layer,

indicates:

an access unit which is suitable for accessing at least two layer data sets which have data models of a corresponding number of build material layers to be selectively solidified during production and characterized in a data model by means of which beam the build material adjoins the respective object cross section to solidify appropriate bodies,

characterized by a fixing unit which is suitable for defining in a layer data set a plurality of adjoining partial cross sections, that is to be solidified subregions of an object cross section, it being determined for each of the partial cross sections with which beam the points in this partial cross section are to be solidified,

wherein the partial cross-sections are set so that a boundary region, that is, an area lying at the boundary between different partial cross-sections, in its shape and / or position in the layer plane is different from the shape and / or position of a boundary region in a layer data record assigned to the immediately preceding or the immediately following layer, and

a provisioning unit which is suitable for providing the shift data record modified by the setting unit as a control data record for the generative layer building apparatus.

In particular, the device according to the invention is suitable for carrying out any of the variants of the method according to the invention for generating a control data record. The mentioned access unit can be an input interface which can read data from a mobile data carrier or receives data via a network or else reads out data directly from a memory. In particular, the device according to the invention can not only be implemented as a separate unit, but can also be part of a more comprehensive EDP system (for example, a CAD design system) or integrated into a generative layer construction device. In the latter two cases, the access unit is then preferably a software interface that communicates with other system components. In particular, the device according to the invention does not necessarily have to be part of a generative layer construction device. This is advantageous because it may be the case that layer data sets for an object to be processed are not present at the location of the generative layer construction device, but rather where the object to be processed has been designed. In addition, the access unit can also access layer data records which are stored in a memory present in the device according to the invention. On the other hand, a close coupling of the device according to the invention for generating a control data record to a generative layer construction device for which the control data record is generated, is advantageous, since then rapid technical constraints specified by the generative layer construction device (eg changing process parameters, how the installation space temperature, etc.) can be reacted, A computer program according to the invention comprises program code means for carrying out all steps of a method according to the invention for generating a control data set or a generative layer construction method according to the invention, when the computer program is executed on a data processor, in particular a data processor cooperating with a generative layer construction device. "Interaction" means that the data processor is either integrated into the generative layer construction device or can exchange data with it.

The implementation of the method according to the invention for generating a control data record and the associated device by means of software allows easy installation on different EDP systems at different locations (for example, the creator of the design of the object to be processed or the operator of the generative layer building apparatus).

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 and 3 each show a schematic plan view of a partial region of the construction field of a generative layer construction device for explaining the procedure according to the invention, FIG. 2 shows a schematic representation of a method according to the invention for generating a control data set for a generative layer construction device, 5 shows the schematic structure of an apparatus for generating a control data record according to the present invention,

6 shows a schematic plan view of a partial region of the construction field of a generative layer construction device for explaining the procedure according to the invention,

7 and 8 each show a schematic section through a layer stack in the

Production of an object for explaining the procedure according to the invention,

9 shows how the mutual distance d of two boundary regions in superimposed layers can be determined,

10 illustrates a variant of the invention in which it is applied to the contour region of an object cross section, and

FIG. 11 shows a schematic plan view of a construction field of a generative layer construction device for explaining the procedure in the presence of a plurality of solidification beams.

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. It should be noted at this point that in the present application, the term "number" always in the sense of "one or more" to understand. It should also be noted 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, even in cases in which only one object is mentioned.

For constructing 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 is arranged with a container wall 6. 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 integrally formed 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, the object 2 to be formed in the container 5 on the building platform 12 is shown below the working plane 7 in an intermediate state with a plurality of solidified layers surrounded by building material 13 which has remained unconsolidated.

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 radiant heater 17 may be arranged, which serves for heating the applied building material 15. As radiant heater 17, for example, an infrared radiator can be provided.

The exemplary laser sintering device 1 further includes 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 mounted on 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 into the device, in particular into the control device. In operation, the carrier 10 is lowered layer by layer by the control device 29, the coater 16 is driven to apply a new powder layer and the deflection device 23 and optionally also the laser 21 and / or the focusing device 24 driven to solidify the respective layer to the respective Object corresponding locations 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 Laser (VCSEL) or Vertical External Cavity Surface Emitting Laser (VECSEL), or a row of these lasers. In general, instead of a laser, any device can be used with which energy can be selectively applied to a layer of the building material as electromagnetic radiation or particle radiation. Instead of a laser, for example, another light source, an electron beam or any other energy or radiation source can be used, which is suitable to solidify the building material. The specific structure of a laser sintering or melting device shown in FIG. 1 is therefore only an example and can of course also be modified, in particular when using a different exposure device than the one shown.

Although a laser sintering or laser melting device has been described as an example of a generative layer construction device in FIG. 1, the invention is not based on laser sintering or laser melting restricted. It may also be used in conjunction with other methods of generatively producing a three-dimensional object by layering and selectively strengthening a building material. Here, by way of example only, laser melting, FLM (application of a thermoplastic material from a die), 3D printing, mask sintering and stereolithographic processes are mentioned. If it is not a laser sintering or laser melting process, then the exposure device 20 is replaced by another insertion device depending on the method, in the case of a 3D printing process by a device which injects one or more binder beams onto the building material a stereolithography process by a UV light source. In all cases, the entry device contains any type of radiation source from which at least one beam impinging on the construction material is directed. In this case, the present invention idea can be realized most advantageously in connection with a generative layer construction device in which an insertion device is set up so that it can direct a plurality of beams onto a region of a building material layer.

Even if reference is made in the further course to the description of the invention to a laser sintering or laser melting device, this is done only as an example and the statements apply correspondingly also for other types of generative Schichtbauvorrich- lines, as just sketched.

As a building material in a generative layer construction method, various materials may be used, preferably powders or pastes or gels, in particular metal powder, but also plastic powder, ceramic powder or sand, whereby the use of filled or mixed powders is possible. Especially in stereolithography (liquid) photopolymers are used.

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 instruction set which is a statement of how to place layers of the construction material one after the other. and selectively irradiate portions of the respective layers corresponding to the cross section of an object to be manufactured with the laser radiation to solidify the building material. The control instruction set thus contains information about the points to be consolidated within a layer and the type of decomposition of the object to be produced into layers.

In detail, the control command set is based on a computer-based model of the object (s) to be produced, preferably a CAD solid model. Furthermore, production-specific information also flows into the control instruction set, for example the position and orientation of the objects in the container 5 or a beam diameter when a laser beam strikes the building material. Finally, the control instruction set also contains the layer information, i. how the object (s) to be produced are subdivided into layers that correspond to the building material layers during the layered generative production. The control instruction set defines, in particular, the thickness of the layer application and the locations at which solidification of the building material is to be effected by irradiation for each building material layer during production. The control instruction set can thus be regarded as a totality of all control data predetermined for the control of the production process in a generative layer construction device. The control data related to a single layer are also referred to as a layer data set. In particular, the control instruction set also contains all for controlling the

Exposure device required data, whereby u.a. the energy density of the radiation emitted by the exposure device and, if appropriate, the travel speed of the jet can be defined via the construction field 8. The procedure according to the invention is described below by way of example with reference to FIGS. 2 to 5.

As shown in FIG. 5, an apparatus 100 according to the invention for generating a control data record for a specific generative layer building apparatus includes an access unit 101, a determination unit 102 and a provision unit 103 Apparatus 100 for generating a control data record will be described with reference to FIG. Figures 2 and 3 serve to further illustrate.

Here, Fig. 2 shows a plan view of a partial area of the construction field 8 of a generative layer building apparatus in which the working areas of two solidifying beams or beam bundles, i. the locations in the construction field, to which the two solidification jets or, respectively, beam bundles can be directed, are shown. Analogous to FIG. 11, AI and A2 denote those regions in which only the first or second hardening beam, eg, the second or the second solidification jet, is formed. As a laser beam, can get used in the solidification. The area within which both solidification jets can be used together for solidification is marked B12.

FIG. 2 shows, by way of example, a parallelogram-shaped object cross-section 55 of an object to be produced, which is to be solidified during the production process in a layer k of the building material. Fig. 2 shows as seen a plan view of the layer k of the building material. In particular, one recognizes a partial cross-section 31 which is to be solidified by means of the first solidification jet and a partial cross-section 32 which is to be solidified by means of the second solidification jet. A boundary region 35 separates both partial cross sections from one another. Basically, the border area 35 is a borderline. Depending on the construction material used and the desired properties of the object to be produced, however, it may be appropriate to have the two partial cross sections 31 and 32, where they adjoin one another, overlap during solidification or to leave a gap between the two partial cross sections. For this reason, in the present application, the term "boundary area" was chosen. In addition, at sufficiently high magnification, any real line can be considered an area.

In a device 100 according to the invention for generating a control data set for a generative layer building apparatus shown in FIG. 5, in order to carry out the computer-assisted method according to the invention in a first step, an access unit is used. unit 101 is accessed at least two shift records of the object to be manufactured. In the process sequence shown in FIG. 4, this is step S1.

The term access means that the access unit reads out a shift data record from a memory or else accepts the data corresponding to the shift data record via a network. The two shift records do not necessarily have to be read together (ie simultaneously). It is also possible that there is a greater time interval between the access operations on the two shift records, for example, one of the two shift records was read in at an earlier time. Likewise, the access unit can also access a memory in the device 100 in which the layer data sets are present.

At first, a layer data set only has to contain information for the associated building material layer at which points of the building material layer during the production of the object a solidification of the building material is to be effected by directing beam bundles onto the building material layer. Of course, other process information (eg layer thickness or beam diameter, etc.) may already be included. In particular, it may already be specified in the layer data record by means of which beam the building material is to be solidified at one point. If the latter information is not yet present in the layer data set, then the device 100 according to the invention determines with which beam the material to be consolidated is to be solidified at one point of the building material layer.

In a step S2 shown in FIG. 4, the definition unit 102 modifies a layer data record in such a way that an object cross-section is divided into a plurality of adjoining partial cross-sections, wherein the decomposition is such that all locations within a partial cross-section are to be solidified with the same beam. Furthermore, the fixing unit 102 determines the partial cross-sections in such a way that the position and / or shape of the boundary regions (in FIG. 2 by way of example only a boundary region 35 is shown) in directly superimposed layers are different from each other. This becomes clear from a comparison of FIGS. 2 and 3:

FIG. 3 shows a plan view of the same subregion of the construction field as FIG. 2. FIG. 3 shows an object cross-section 65 of an object to be produced which is to be solidified in the layer k + 1 of the building material, which during the manufacturing process is directly adjacent to the layer k of FIG 2 follows. Again, one recognizes two different beam bundles associated partial cross sections 41 and 42, which are separated by a boundary region 45. In particular, it becomes clear from a comparison of FIGS. 2 and 3 that the boundary regions 35 and 45 lie at different locations within the construction field and, in particular, do not overlap at any point. This is because, on the one hand, the position (location) of the border areas within the construction field is different and, on the other hand, the shape of the border areas is different: Even if both had the same position, complete coverage would not be possible.

Finally, in a step S3 shown in FIG. 4, the delivery unit 103 provides the shift data record of a generative layer building apparatus modified as a control data record in step S2. As already mentioned above, a control data record can be regarded as a subset of a control command set of a generative layer building apparatus. Of course, a control record provided by the provisioning unit 103 may also be integrated by the provisioning unit 103 itself into a control instruction set. Apart from this, provisioning also includes forwarding the control data record to a data processing device which integrates the control data record into a control command record, or a direct forwarding to a generative layering device. In particular, it is possible to dynamically provide control data for object cross sections still to be produced during a production process in the generative layer construction device.

Furthermore, modified layer data sets according to the invention need not be provided individually for a generative layer construction process. Rather, several Modified shift records first collected and then be provided in their entirety as a control record.

For the manner of varying the position and / or shape of the boundary regions in superimposed layers, there are many possibilities for achieving the desired advantages, in particular good mechanical parameters in the object or uniform surfaces. Depending on the used building material and boundary conditions in the solidification or shape of the object to be produced, position of the object in the space, etc., you can even allow a partial coverage of border areas.

Likewise, one can allow coverage by a boundary in the nth layer after the current layer. With n = 2, an overlap in the next but one layer would be allowed. Of course one can also specify higher values for n, for example n = 3, n = 5 or n = 17 or n = 101. Preferably, a prime number is chosen as the value for n.

With regard to a good mechanical stability of the manufactured objects, it may even be advantageous if the position and / or shape of a boundary region repeats after at least m layers (m> n). In particular, a regular (periodic) repetition can be of advantage here. Such a procedure is to be illustrated with reference to FIGS. 7 and 8:

Fig. 7 shows a schematic section through a layer stack in the manufacture of an object. The horizontal lines shown here are each intended to represent a layer in the data model that corresponds to a building material layer during the production of the object. Layer thicknesses are neglected in the scheme (as well as in Fig. 8). For the sake of simplicity, it is further assumed that in the section of FIG

Layer stack, the object cross-sections each occupy the entire width of the section and are divided into partial cross-sections 701 and 702, respectively. Reference numerals are assigned for convenience only to the top three layers in FIG. 7). One recognizes in the cut in each layer a border area 705 (the reference number is again only for two layers shown), which assumes the same position again after five layers. Although the boundary areas do not overlap in directly superimposed layers at any point, the boundary areas in the layer plane (ie horizontally in FIG. 7) are distributed over only an area of limited extent. Depending on the application, it may be appropriate to limit the extent of the area within the construction field, eg. B. to a width of 500 μιη or 200 μιη or 100 μηι. It is also possible to specify minimum values for the shift of the position of the boundary region from layer to layer, for. B. 5 μητι, 20 μηι or even 50 μηη. 9 shows how the mutual distance d of two boundary regions in superimposed layers can be determined.

7, it can also be seen that the horizontal layers of the boundary region in the layers can be described by means of a periodic function as a function of the layer number (assuming that higher layer numbers are assigned later in the manufacturing process to layers to be consolidated than earlier in the production process to be consolidated layers). In the example of FIG. 7, one could approximate the change in the positions of the boundary regions in the direction of construction (ie from layer to layer) by means of a sawtooth function.

FIG. 8 shows a similar example with partial cross-sections 801 and 802 and boundary regions 805, which assume the same position within the layer plane in every other layer. Again, the locations can be approximated by a sawtooth function. In particular, Fig. 8 illustrates how by the periodic change in the position of the boundary regions, a toothing of partial cross sections takes place by z. B. a partial cross section 802 where it adjoins the boundary region 805, is flanked in the layers immediately above and below partial cross sections 801,

In the same way, one could modify the positions and / or shapes of the boundary regions in the individual layers so that they can only be approximated by more complicated functions. For example, a simple periodic function, such as a legal corner, sawtooth or sine function, another periodic function superimposed on a smaller amplitude (similar to a harmonic wave).

For a particularly thorough variation of the positions and / or shapes of the boundary regions, it is advisable to introduce a random element, for example by slightly shifting the locations in FIG. 7 or 8 in a slight manner, so that the approximated sawtooth function is "noisy" as it were , Alternatively, one can specify the layers and / or shapes of the boundary regions in the layers solely by a random function.

Although hitherto in the figures, variations of the positions of the boundary regions in the layer plane have been shown primarily, this does not mean that the shapes of the boundary regions can not also be varied in the manner described. For example, FIG. 6 shows an alternative shape of the boundary region compared to FIGS. 2 and 3. It can be seen in Fig. 6, the absence of "corners" in the shape of the boundary region. In contrast, the shape of the boundary region in FIGS. 2 and 3 takes account of the fact that regions to be solidified in a layer are usually scanned strip-wise with a beam. That is, within a rectangular or square area (a stripe), the hardening beam travels in parallel tracks over the building material. The angular course of the respective boundary region in FIGS. 2 and 3 results from the fact that the partial cross-sections have been selected such that strips bordering on the boundary region adjoin one another in the respective partial cross-sections. It can be seen in FIGS. 2 and 3 that the boundary region in FIG. 2 has been modified in its position and shape such that straight sections of the linear shape of the boundary region have been displaced in parallel in the layer plane. In the case of a variation of the position of the boundary regions, it is likewise possible to obtain the position of a boundary region in a subsequent layer by twisting the position of the boundary region in the underlying layer about an axis of rotation perpendicular to the layers. 10 illustrates a variant of the procedure according to the invention in which this method is also applied to boundary regions which lie in the contour of an object cross section and delimit therefrom two sections of the contour region which are solidified by different hardening beam bundles. Correspondingly, in FIG. 10, an object cross-section 95 can be seen, whose contour region (edge) has two sections 91 and 92 which are solidified by means of different hardening beams or hardening beam bundles.

Usually, a contour region is solidified in such a way that the hardening beam used, which has a certain diameter where it encounters the building material, moves away from the contour. Therefore, it is permissible to designate sections of the contour of an object cross section as two-dimensional areas. The same applies to the point at which two sections of the contour area adjoin one another. As in the interior of an object cross-section, where two partial cross-sections adjoin one another, it is also true in the contour region that two sections will generally not exactly adjoin one another but there will be a slight gap or slight overlap at the boundary. Therefore, the two boundary points 9192 and 9291 in Figure 10 are referred to as boundary regions. To differentiate the two boundary regions from one another, arrows indicate the directions in which the solidification rays are moved starting from the boundary regions. The boundary area 9192 is thus that from which the partial cross section (contour section) 92 is solidified, and the boundary area 9291 is that from which the partial cross section (contour section) 91 is solidified.

Also in the contour region, the position of the boundary region is varied according to the invention from layer to layer in the same way as has been described above for boundary regions lying in the interior of an object cross-section.

A change in the position of a boundary region in the contour is particularly useful for surface areas that are optically perceptible or have to be designed as uniformly as possible. In inaccessible surface areas, on the other hand, Soon beads or dents on the surface of the object can be tolerated. Accordingly, it makes sense to proceed according to the invention differently in different sections of the object to be produced. In particular, the position and / or shape of the boundary regions in different subsections of the object can not only be varied differently, but rather the procedure according to the invention can generally be limited to only one or more subsections of the object determined in advance.

Finally, it should be mentioned that a device 100 according to the invention for generating a control data set of 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 implemented as software modules, for example if the data fed in or output via them can be taken over by other components already implemented on the same device or must be passed to another component only by software. Similarly, the interfaces could consist of 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

claims

A computer-aided method for generating a control data set for a generative layer building apparatus for producing a three-dimensional object by means of the same, the production comprising the steps:

Building the object layer by layer, and

controlled directing radiation of at least one radiation source (21) through regions of a layer of a building material (15) onto an object cross section through an insertion device (20)

wherein the insertion means (20) is adapted to direct a plurality of beams (22) to different regions of a deposited layer, each of the beams (22) being incident on the building material (15) where it impinges on the layer. works, in particular so that it is solidified,

wherein the method for generating a control data record comprises:

a first step (S1) of access to at least two layer data records which comprise data models of a corresponding number of build material layers to be selectively solidified during fabrication, wherein in a data model an object cross section is identified corresponding locations at which solidification of the build material (15 ) to be held,

wherein it is characterized in a data model which of the plurality of beam bundles (22) is intended to consolidate the building material (15) at which of the locations corresponding to the respective object cross-section,

characterized in that in a second step (S2) in a layer data set a plurality of adjacent partial cross sections (31, 32, 41, 42), ie to be solidified subregions of an object cross section are defined, wherein for each of the partial cross sections (31, 32, 41, 42 ) determines with which beam (22) the points in this partial cross-section are to be solidified, wherein the partial cross-sections (31, 32, 41, 42) are set such that a boundary region (35, 45), ie an area lying at the boundary between different partial cross-sections (31, 32, 41, 42), in its shape and / or or position in the layer plane is different from the shape and / or position of a boundary region (35, 45) in a layer data record assigned to the immediately preceding or immediately following layer, and

in a third step (S3), the modified shift data record in the second step (S2) is provided as a control data record for the generative layer building apparatus. 2. Computer-aided method according to claim 1, wherein the boundary regions (35, 45) in at least two successive layers do not completely cover each other, preferably to cover 0%.

3. Computer-aided method according to one of the preceding claims, wherein the shape and / or position of the boundary region (35, 45) are set in the layer plane so that they are in the manufacturing process at the earliest n layers, where n is a natural number greater than one , to repeat.

4. A computer-aided method according to claim 3, wherein the shape and / or position of the boundary region (35, 45) are determined in the layer plane so that they m in the manufacturing process after m layers, where m is a natural number greater than or equal to n to repeat.

5. Computer-aided method according to one of the preceding claims, wherein the shape and / or position of the boundary region (35, 45) changes in the layers in the construction direction according to a first periodic function, in particular a sine function, triangular function or rectangular function / change.

6. A computer-aided method according to claim 5, wherein the shape and / or position of the boundary region (35, 45) in the layers in the construction direction additionally according to a two- the periodic function is superimposed on the first periodic function and preferably has a shorter period than the first periodic function.

7. Computer-aided method according to one of the preceding claims, wherein the boundary region (9192, 9291) delimits two sections (91, 92) of a contour region of an object cross-section against each other.

A computer-aided method according to any one of the preceding claims, wherein in at least one layer the position of the boundary region (35, 45) is twisted compared to another layer, preferably by an angle greater than or equal to 5 °, more preferably by one Angle greater than or equal to 10 °, even more preferably an angle greater than or equal to 20 °, provided that the shape of the boundary region in the two layers is substantially equal. 9. A computer-aided method according to any one of claims 1 to 4, wherein the shape and / or position of the boundary region (35, 45) in the layers change in the direction of construction according to a random function.

10. A computer-aided method according to any one of claims 5 to 6, wherein the shape and / or position of the boundary region (35, 45) in the layers changes in the direction of construction according to a function resulting from an overlay of the first and / or second periodic function with a random function.

A computer-aided method according to any one of the preceding claims, wherein the change in shape and / or position of the boundary region (35, 45) from layer to layer is dependent on whether the boundary region is in a preestablished portion of an object to be fabricated.

12. Computer-aided method according to one of the preceding claims, wherein in the second step at least one section of at least one object cross-section in Ab- Depending on the quality of the section and / or the production time of the object, the number of beam bundles (22) required to consolidate the building material within this section is determined. 13. A generative layer construction method for producing a three-dimensional object by means of a generative layer construction apparatus, the production comprising the steps:

Structure of the object layer by layer,

wherein the insertion means (20) is adapted to direct a plurality of beams (22) simultaneously to different regions of the deposited layer, each of the beams, where incident on the layer, acting on the building material (15), in particular so that this is solidified,

wherein the generative layer manufacturing method for manufacturing uses a control data set generated by a method for generating a control data set according to any one of the preceding claims.

14. An apparatus for computer-aided generation of a control data set for a generative layer building apparatus for producing a three-dimensional object by means of the same, the production comprising the steps:

Structure of the object layer by layer,

wherein the insertion means (20) is adapted to direct a plurality of beams (22) simultaneously to different regions of the applied layer, each of the beams (22) acting on the building material (15) where it impinges on the layer in particular so that it is solidified, wherein the apparatus for computer-aided generation of a control data record comprises:

an access unit (101) adapted to access at least two slice datasets having data models of a corresponding number of build material layers to be selectively solidified during fabrication and immediately overlaid,

wherein it is characterized in a data model, by means of which beam (22) the building material is to be solidified at the locations corresponding to the respective object cross-section,

characterized by a determining unit (102) which is suitable for defining in a layer data set a plurality of adjoining partial cross sections (31, 32, 41, 42), ie subregions of an object cross section to be consolidated, it being determined for each of the partial cross sections with which beam bundle (22 ) to consolidate the points in this partial section,

wherein the partial cross sections are determined so that a boundary region (35, 45), ie a region located at the boundary between different partial cross sections, in its shape and / or position in the layer plane with respect to the shape and / or position of a boundary region (35, 45 ) is different in one of the immediately preceding or the immediately following layer associated layer data set, and

a provisioning unit (103) that is suitable by the fixing unit

(102) provide a modified layer data set as a control data set for the generative layer building apparatus.

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 on a data processor, in particular a data processor cooperating with a generative layer building apparatus.