Method and device for improving the bonding of a thin structure

Abstract

The invention relates to a method for improving the bonding of a thin structure (W) to an extended volume in an object (2) produced layer by layer on the basis of a virtual three-dimensional object model (M) by solidifying a pulverulent building material using radiation, said method having the steps of: - ascertaining the number of connection points (A) in the object model (M) at which a structure (W) with a thickness below a specified threshold connects to a volume boundary (B), the thickness of which exceeds a specified threshold, - specifying a manufacturing mode (F) for a number of ascertained connection points (A) such that, for a connection point (A) of a structure (W) for connecting to a volume boundary (B), the contact surface between the structure (W) and the volume boundary (B) is enlarged and / or a profile of beam parameters for manufacturing the structure (W) is specified and / or a manufacturing sequence is specified, according to which the structure (W) is manufactured prior to or at the same time as the manufacture of the corresponding volume boundary (B), and - changing the object model (M) and / or generating control data (PS) for manufacturing an object (2) from the object model (M) according to the specified manufacturing mode (F). The invention also relates to control data, to a device, and to a manufacturing device.

Description

[0001] Method and device for improving the connection of a thin structure

[0002] The invention relates to a method and a device for improving the connection of a thin structure, control data and a manufacturing device.

[0003] In additive manufacturing, where a powder (or a powdered build material) is solidified layer by layer to form an object, the connection of thin structures to an extended structure ("bulk") can be problematic.

[0004] With today's technologies, solidifying thin structures in the range of 100 to 200 micrometers is no problem. For example, a laser beam with a focal point of 50 micrometers can create a melt pool with a width of approximately 100 micrometers. This allows for the creation of very thin walls, for example, for thin but stable infill or for heat exchanger structures.

[0005] During the fabrication of extended structures, the effect of material thinning in their surroundings can occur. For example, during their production from a beam-induced melt pool, powder from the surroundings can be drawn into the structure by expansion and subsequent contraction of the melt, or it can be pushed away from the structure by pressures generated by the spontaneous evaporation of material.

[0006] For example, several effects can occur during direct metal laser sintering (DMLS): When the laser beam strikes the powder, a melt pool dynamic is created. First, the powder melts and expands. As the laser continues to move (at its high speed), the melt solidifies very quickly due to the rapid cooling rate. This creates stresses and also a reduction in volume. The Marangoni effect typically occurs at the surface. Due to the expansion, powder in the vicinity of the hot melt can adhere to it. The higher the energy input, the more pronounced this effect can be. When the melt contracts during solidification, the adhered powder is no longer present in the area of ​​the former melt. Furthermore, due to the penetration of heat into deeper layers, locally high vaporization pressures can occur, which can eject powder from these areas.Consequently, an extensive melt not only reduces the amount of surrounding powder by carrying it inwards, but also by extracting it outwards.

[0007] The contraction of the melt can also cause the wall of the extended structure (the "bulk") to be slightly concave, so that a thin wall no longer touches the structure at its intended endpoint.

[0008] Although all these effects generally operate within a very small area on the order of a few tens to hundreds of micrometers, this can have serious implications for the bonding of very thin walls.

[0009] The object of the invention was to provide a method that overcomes the disadvantages of the prior art and allows for improved connection of a wall to an extended volume.

[0010] It is an object of the present invention to provide a method and a device for improving the connection of a thin structure to an extended volume, as well as corresponding control data and a manufacturing device with which the disadvantages described above are avoided.

[0011] This task is solved by a method according to claim 1, control data according to claim 8, a device according to claim 9 and a manufacturing device according to claim 10.

[0012] A method according to the invention serves to improve the connection of a thin structure (e.g., a wall or a strut) to an extended volume in a layer-by-layer fabricated object based on a virtual three-dimensional object model by solidifying a powdered build-up material using radiation. The method comprises the following steps:

[0013] - Determining a number of connection points in the object model where a structure with a thickness below a specified limit connects to a volume boundary whose thickness exceeds a specified limit,

[0014] - Specifying a manufacturing mode for a number of identified connection points such that, for a connection point of a structure to a volume boundary, the contact area between the structure and the volume boundary is increased and / or a profile of beam parameters for manufacturing the structure is specified and / or a manufacturing sequence is specified according to which the structure is manufactured before or together with the corresponding volume boundary, - Modifying the object model and / or generating control data for manufacturing an object from the object model according to the specified manufacturing mode.

[0015] The layer-by-layer fabrication of objects based on a virtual three-dimensional object model by solidifying a powdered build-up material using radiation is well-established and need not be described here. In common processes, the object model is usually available as a CAD object or as a surface object in the form of geometric data, e.g., in a file. The object model can, for example, be a pure volume model in which the thin structures are formed with a small extent or wall thickness. However, it can also be composed of two or more sub-models, at least one of which is a surface model describing the thin walls. The thin structures in the object model can be represented, in particular, as struts, surfaces, or lines (or curves).Using a laser (or another radiation source), the object is then manufactured according to generated control data in such a way that a large number of powder layers are applied one after the other and successively solidified according to the data of the object model.

[0016] In this process, thin walls in the object model that abut an extended volume may not form a tight seal in the finished object, for example, due to a lack of powder at the bonding point. This method solves this problem. It should be noted that the problem is relatively easy to visualize in the X / Y plane (where, for example, the structure and volume boundary are both perpendicular). However, the method also solves problems in the Z plane, for example, when the structure rests on an extended base or when an extended top is placed on a thin structure. While the effect of powder being carried along by the melt does not apply here, since the powder is applied layer by layer, bonding the thin structure to an extended layer can still be problematic for other reasons.

[0017] The method first identifies the connection points in the object model where a thin structure connects to an extended volume. A thin structure is defined here as a structure with a thickness below a predefined threshold. This threshold can be expressed as a size, e.g., in mm, or as a number of hardening lines. For example, any wall-like structure or strut thinner than 0.5 mm can be considered a thin structure, as can any structure consisting of fewer than 5 adjacent hardening lines. Preferably, the threshold is less than 1 mm, more preferably less than 0.5 mm, and particularly less than 0.2 mm. With respect to the number of hardening lines, the threshold is preferably less than 10, more preferably less than 5, and particularly less than 3.

[0018] Essentially, a thin structure is a structure in which at least one spatial dimension is thin according to the preceding definitions. This can be a wall (in which case the word "wall" can be used instead of "structure") or a rod-like structure (in which case the word "rod" or "strut" can be used instead of "structure"). Here, a wall can also be understood as a two- or three-dimensional curved surface. In this application, the word "structure" is also used as an abbreviation for "thin structure." However, this must be distinguished from the "extended structure," which is essentially the type of structure to which the volume boundary belongs.

[0019] The extended volume can be an extended structure (“bulk”) or simply a thick wall or strut. This extended structure can again be curved in two or three dimensions. It is generally referred to here as a “volume boundary” because, for bonding the thin structure, essentially only the surface area of ​​the volume is relevant. However, a certain amount of melt pool must be generated for this surface, which is why its thickness must exceed a predetermined limit. This limit can again be specified in terms of length or in the number of hardening lines (since each new line transfers additional energy to the relevant location). Preferably, this limit is greater than 2 mm, preferably greater than 5 mm, and particularly greater than 7 mm. With respect to hardening lines, the limit is preferably greater than 10, preferably greater than 15, and particularly greater than 20.Beyond a certain point, the energy input becomes irrelevant, as the energy is no longer manifested at the connection point. However, this depends on the thermal conductivity of the building material. The determination can be carried out in a program used to create or view an object model, or in a program designed to generate control data for manufacturing an object according to the object model.

[0020] A manufacturing mode is now determined for a number of identified connection points, but not necessarily for all of them. This manufacturing mode specifies how the respective connection point is to be manufactured. This manufacturing mode can encompass or consider several aspects.

[0021] To improve the bonding of the thin structure to the volume boundary, the contact area between the structure and the boundary can be increased at the connection point, for example, by making the structure thicker there, by using more hardening lines, or by slightly overlapping the structure with the boundary. Alternatively or additionally, a profile of blasting parameters can be specified for manufacturing the structure, for example, that a higher power is applied locally at the connection point than for hardening the rest of the structure. Alternatively or additionally, a manufacturing sequence can be specified, for example, that the structure is manufactured before or at the same time as the volume boundary.

[0022] A time-based specification has the advantage that a solidified surface already exists in the area of ​​the volume boundary before its production. Powder cannot be removed from the melt or blown away there, which would later contribute to the structure, as the structure has already solidified.

[0023] Increasing the contact area has the advantage of providing additional stability to the connection. The structure can, for example, extend into the volume boundary (possibly even into its infill) or be thickened at the connection point, for example, with additional hardening lines or a conical transition. This increase in size can be achieved by prefabrication of the structure, but the thickening can also be manufactured together with the volume boundary, for example, by creating a trumpet-shaped transition as part of the volume boundary and extending the structure into this transition.

[0024] The beam parameter profile can, for example, specify that the structure is manufactured at a higher power at the connection point than in the rest of the area. This can be achieved by temporal modulation of the beam (continuous operation in the connection area, pulsed operation in the rest of the area) or by energetic modulation (high energy in the connection area, lower energy in the rest of the structure), or the intensity can be controlled accordingly (high intensity in the connection area, lower intensity in the rest of the structure).

[0025] This predefined manufacturing mode can now be used to modify the object model, for example, to change its geometry by thickening the connection points or to modify manufacturing parameters. Alternatively or additionally, control data for manufacturing an object can be generated and output from the object model according to the predefined manufacturing mode. Ultimately, this step ensures that an object can be manufactured according to the manufacturing mode with improved connections to the thin walls.

[0026] The control data according to the invention were created using the inventive method. They differ from conventional control data because they specifically include geometric changes to the model (e.g., thickenings) and / or specific manufacturing sequences (e.g., thin walls in front of thick volume boundaries) and / or specifications for different beam guidance in the case of the thin walls (e.g., solidifying the connection point with more power than the rest of the structure).

[0027] An apparatus according to the invention serves to improve the connection of a thin structure to an extended volume in a layer-by-layer manufactured object based on a virtual three-dimensional object model by solidifying a powdered build material by means of radiation; the method comprises the following components:

[0028] - a detection unit designed to determine a number of connection points in the object model where a structure with a thickness below a specified limit ("thin structure") connects to a volume boundary whose thickness exceeds a specified limit,

[0029] - a manufacturing mode unit designed to specify a manufacturing mode for a number of identified connection points such that, for a connection point of a structure to a volume boundary, the contact area between the structure and the volume boundary is increased and / or a manufacturing sequence is specified according to which the structure is manufactured before or with the corresponding volume boundary, - a modification unit designed to modify the object model and / or generate control data for manufacturing an object from the object model according to the specified manufacturing mode.

[0030] The function of the device's components has already been described. The device is preferably designed for carrying out a method according to the invention. The device ensures that thin structures are optimally bonded to other structures of an object. The device, with its manufacturing mode unit, can effectively counteract the disadvantages mentioned above, namely that extended structures ingest powder in their surroundings.

[0031] A manufacturing device according to the invention for carrying out a manufacturing process in which an object is built up based on a virtual three-dimensional object model by layer-by-layer solidification of a powdered build-up material by means of radiation, comprises a control device for controlling the manufacturing process and a device according to the invention.

[0032] The invention can be implemented, in particular, in the form of a computer unit with suitable software. The computer unit can, for example, comprise one or more cooperating microprocessors or the like. In particular, it can be implemented in the form of suitable software program components within the computer unit. A largely software-based implementation has the advantage that even previously used computer units can be easily retrofitted by a software or firmware update to operate according to the invention. In this respect, the problem is also solved by a corresponding computer program product with a computer program that can be directly loaded into a memory device of a computer unit, containing program sections to execute all steps of the method according to the invention when the program is run in the computer unit.In addition to the computer program itself, such a computer program product may include additional components such as documentation and / or additional components, including hardware components such as hardware keys (dongles, etc.) for using the software.

[0033] For transport to the computer unit and / or for storage on or in the computer unit, a computer-readable medium, such as a memory stick, a hard drive or other portable or permanently installed data carrier, can be used, on which the program sections of the computer program that can be read and executed by a computer unit are stored.

[0034] Further, particularly advantageous embodiments and developments of the invention result from the dependent claims and the following description, wherein the claims of one claim category may also be further developed analogously to the claims and description parts of another claim category and, in particular, individual features of different embodiments or variants may be combined to form new embodiments or variants.

[0035] Preferably, a connection point is determined by searching the object model for walls with a thickness below the specified limit and for the area of ​​contact between these walls and the volume boundaries of the object model. The object model can be searched for structures that extend along a length and whose thickness or height (essentially their extent in a spatial direction) falls below the limit. Similarly (but with the other limit for their minimum thickness), the volume regions can be determined. Connection points are then defined where the structures meet the volume regions (in the "contact area").

[0036] Preferably, a contact area is considered a connection point only if the wall extends within a predetermined angle range around the surface normal of the volume boundary. This angle range is preferably less than 120°, or plus / minus 60° to the surface normal of the volume boundary. With angled connection points, even a thin wall could have a sufficient contact area with the volume boundary. It could be advantageous here that, above a predetermined limit angle, only one-sided thickening of the structure occurs, specifically between the structure and the extended volume. It is also preferred that the manufacturing mode is selected depending on the angle. Here, the detection unit can preferably decide, based on predetermined limit angles, whether and what kind of reinforcement is required, i.e., which manufacturing mode should be applied, and communicate this to the manufacturing mode unit.This could also determine the manufacturing mode unit. This design can be particularly advantageous for curved structures.

[0037] Preferably, the manufacturing method modifies the connection point such that the thin structure is extended into the volume boundary for a predetermined distance. The thin structure thus overlaps the volume region (of the extended volume). The overlap area can be irradiated multiple times: once during the fabrication of the structure and once during the fabrication of the volume region. The thin structure can extend into the infill of the volume region. The overlap area is preferably longer than 0.1 mm, particularly longer than 0.5 mm, but preferably shorter than 5 mm or preferably a predetermined multiple of the structure's thickness. This increases the contact area between the structure and the volume boundary.

[0038] The length by which the structure projects into the volume can preferably depend on its thickness. For this purpose, a factor can be defined by which the thickness of the structure is multiplied or divided to determine the length of the overlap. This factor can also be divided by the thickness of the structure. This results in the portion of the structure projecting into the volume becoming smaller as the structure's thickness increases. For example, the length S of the overlap can be calculated using the given factor f and the thickness D of the structure via the formula S = f ■ D or the formula S = f / D. The factor f is preferably between 1 and 50, and most preferably between 3 and 10.

[0039] Preferably, the extended portion is thicker than the structure. However, it can also preferably become thicker with increasing penetration depth. This has the advantage that the structure interlocks with the volume boundary.

[0040] Preferably, the manufacturing process dictates that the connection point is thickened in a predetermined area upstream of the volume boundary. This area preferably ends less than 5 mm from the volume boundary, preferably less than 3 mm, or even less than 2 mm. Structures are preferably added that run parallel to and touch the existing structure, e.g., additional hardening lines parallel to those of the existing structure. Alternatively or additionally, the structure is widened parallel to the existing structure. Alternatively or additionally, a conical or trumpet-shaped transition is formed between the structure and the volume boundary, in particular a trumpet-shaped transition with radii or Mattek radii. Besides improving the connection, such a thickening also has an advantageous stiffening effect.

[0041] Preferably, the manufacturing method specifies that the structure at the connection point is manufactured with different beam parameters than other areas of the structure. Preferably, the structure at the connection point is manufactured with a higher power output and / or a larger beam diameter. Compared to the manufacturing of the rest of the structure, it is preferred that at the connection point:

[0042] - the power of continuous radiation is higher, and / or

[0043] - the beam duration (in the case of PWM this corresponds to the duty cycle) of a pulsed radiation is higher (e.g. continuous), and / or

[0044] - a higher energy input occurs, and / or

[0045] - a different energy distribution at the radiation point (e.g., a different beam shaping design) is used, and / or

[0046] - a larger radiation point is used.

[0047] All of this increases the heat input. It is important that the connection point is manufactured with a higher heat input than the rest of the structure in question.

[0048] According to a preferred embodiment of the method, the connection point is formed as part of the volume boundary, preferably together with a part of the structure, wherein the hardening vectors for manufacturing the volume boundary are preferably designed such that they form the connection point and preferably also a part of the structure. For example, the edge of the volume boundary can extend into the structure over a radius, or a hardening path can begin as the edge of the volume boundary and end as part of the structure.

[0049] Preferably, the manufacturing process also specifies a local thickening of the volume boundary in the area of ​​the connection point. This can be done as an alternative to, or in addition to, a thickening of the structure itself.

[0050] It should be noted that a manufacturing method does not have to be identical for all connection points. Depending on the thickness of the structure, its angle to the volume boundary, and / or the length of the structure, or depending on a given load profile, different manufacturing methods could be specified for different connection points.

[0051] It is also preferred to optimize the geometry or scan patterns for a smooth transition between a thin structure and a solid component area. In particular, horizontal webs with downskin in a fine grid (e.g., with a grid spacing of 1 to 1.5 mm) achieve better bonding through local double single vectors and optimized energy input.

[0052] Preferably, before determining a number of connection points in the object model, the object model is conceptualized and designed and created, particularly using a CAD program. The object model can be a solid model with thin structures of small dimensions, or a solid model combined with, or at least partially created from, surface elements, where the surface elements describe the thin structures. The determination of thin structures and their connection points to a solid boundary is carried out as already described above in relation to the inventive method.

[0053] Preferably, connection points are determined in 2D layers of a layered object model or in a 3D object model M.

[0054] Preferably, the system prompts the user to choose between manual and automatic geometry adjustments. Manual adjustments can be made directly on the object model by the user, although it is preferable for the connection points to be automatically marked in a CAD program. Since the connection points and their positions are already known, marking them is straightforward.

[0055] As previously described, for example, the contact area between the structure and the volume boundary can be increased at the connection points, a profile of beam parameters for manufacturing the structure can be specified, or a manufacturing sequence can be defined according to which the structure is manufactured before or together with the corresponding volume boundary. This is done according to a predefined manufacturing mode. Thus, for example, beam parameters can be adjusted for some of the connections, thickening of the connection points can be carried out for another part, and manufacturing sequences can be specified for yet another part.

[0056] Finally, control commands for constructing an object according to the object model, taking into account the modifications, are generated, and a final setup of the manufacturing device is performed if necessary. Alternatively, the object model can be modified according to the modifications and then divided into manufacturing layers. The use of AI-based methods (AI: "Artificial Intelligence") is preferred for the method according to the invention. Artificial intelligence is based on the principle of machine learning and is generally implemented with a learning algorithm that has been trained accordingly. The English term "machine learning" is frequently used for machine-based learning, which also includes the principle of "deep learning." A suitably trained AI can be used to find connection points and / or to define a manufacturing mode.

[0057] Preferably, the detection unit comprises a module with a machine learning model that has been trained to identify connection points in an object model. This can be achieved, for example, by marking connection points as such in a large number of object models, e.g., manually, and then using these marked object models to train the model.

[0058] Preferably, the manufacturing mode unit comprises a module with a machine learning-capable model that has been trained on a specified manufacturing mode for a connection point. This can be achieved, for example, by assigning a preferred manufacturing mode to connection points in a multitude of object models, e.g., manually, and then using these labeled object models to train the model.

[0059] The invention is explained in more detail below with reference to the accompanying figures and exemplary embodiments. The same components are designated with identical reference numerals in the various figures. The figures are generally not to scale. They show:

[0060] Figure 1 shows a schematic, partially sectional view of an embodiment of a manufacturing device for additive manufacturing with a modification device according to the invention.

[0061] Figure 2 shows an example of how a wall can be connected to a volume boundary.

[0062] Figure 3 Problems when connecting a wall to a volume boundary,

[0063] Figure 4 shows a preferred procedure within the framework of the method according to the invention, Figure 5 shows a preferred connection of a wall to a volume boundary,

[0064] Figure 6 shows another preferred connection of a wall to a volume boundary,

[0065] Figure 7 shows a preferred manufacturing mode,

[0066] Figure 8 shows another preferred connection of a wall to two volume boundaries,

[0067] Figure 9 shows an oblique coupling of a structure,

[0068] Figure 10 shows an interlocking of the structure,

[0069] Figure 11 shows a block diagram of the procedure.

[0070] Figure 12 shows a diagram of a preferred embodiment of the method.

[0071] The following exemplary embodiments are described with reference to a manufacturing device 1 for the additive manufacturing of components in the form of a selective laser sintering or laser melting device, whereby it is explicitly pointed out once again that the invention is not limited to selective laser sintering or laser melting devices.

[0072] Such a manufacturing device 1 is shown schematically in Figure 1. It has a process chamber 3 or process space 3 with a chamber wall 4, in which the manufacturing process essentially takes place. Inside the process chamber 3 is an upwardly open container 5 with a container wall 6. The upper opening of the container 5 forms the current working level 7. The area of ​​this working level 7 located within the opening of the container 5 can be used to build the object 2 and is therefore referred to as the build area 8.

[0073] Container 5 has a base plate 11 that is movable in a vertical direction V and is mounted on a support 10. This base plate 11 closes off the container 5 at the bottom, thus forming its base. The base plate 11 can be formed integrally with the support 10, or it can be a separate plate that is attached to or simply supported by the support 10. Depending on the specific material used, such as the powder, and the manufacturing process, a build platform 12 can be attached to the base plate 11 as a base on which the object 2 is built. Alternatively, the object 2 can also be built directly on the base plate 11 itself, which then serves as the build platform.

[0074] The basic assembly of object 2 is carried out by first applying a layer of the build material 13 to the build platform 12, then selectively solidifying the build material 13 at the points that are to form parts of the object 2 to be manufactured using a laser beam 22 as an energy beam, then lowering the base plate 11, and thus the build platform 12, with the aid of the support 10, and applying and selectively solidifying a new layer of the build material 13, and so on. In Figure 1, object 2, assembled in the container on the build platform 12 below the working plane 7, is shown in an intermediate state. It already has several solidified layers, surrounded by unsolidified build material 13.Various materials can be used as building material 13, preferably powders, in particular metal powders, plastic powders, ceramic powders, sand, filled or mixed powders or pasty materials, and optionally a mixture of several materials.

[0075] Fresh build material 15 is located in a storage container 14 of the manufacturing device 1. With the aid of a coater 16 that can be moved in a horizontal direction H, the build material can be applied in the working plane 7 or within the build area 8 in the form of a thin layer.

[0076] Optionally, an additional radiant heater 17 is located in process chamber 3. This heater can be used to heat the applied build-up material 13, so that the irradiation device used for selective solidification does not have to supply too much energy. This means, for example, that a certain amount of base energy can be introduced into the build-up material 13 using the radiant heater 17, which is naturally still below the energy required for the build-up material 13 to fuse or sinter. An infrared radiator or a VCSEL radiator, for example, can be used as the radiant heater 17.

[0077] For selective hardening, the manufacturing device 1 includes an irradiation device 20, or more specifically, an exposure device 20 with a laser 21. This laser 21 generates a laser beam 22, which is deflected by a deflecting device 23 to trace the exposure paths or tracks (hatch lines) in the layer to be selectively hardened, as defined by the exposure strategy, and to selectively introduce the energy. Furthermore, this laser beam 22 is focused onto the working plane 7 in a suitable manner by a focusing device 24. The irradiation device 20 is preferably located outside the process chamber 3, and the laser beam 22 is directed into the process chamber 3 via a coupling window 25 located in the chamber wall 4 on the upper side of the process chamber 3.

[0078] The irradiation device 20 can, for example, comprise not just one, but several lasers. Preferably, these can be gas or solid-state lasers or any other type of laser, such as laser diodes, in particular VCSELs (Vertical Cavity Surface Emitting Lasers) or VECSELs (Vertical External Cavity Surface Emitting Lasers), or an array of such lasers. Most preferably, one or more unpolarized single-mode lasers, e.g., a 3 kW fiber laser with a wavelength of 1070 nm, can be used within the scope of the invention.

[0079] A control device 30 comprising a control unit 29 serves to control the units of the manufacturing device 1, which controls the components of the irradiation device 20, namely the laser 21, the deflection device 23 and the focusing device 24.

[0080] The control unit 29 also controls the radiant heating 17 by means of suitable heating control data HS, the coater 16 by means of coating control data ST and the movement of the carrier 10 by means of carrier control data TS, thus controlling the layer thickness.

[0081] Control device 30 comprises a device 34 according to the invention for improving the connection of a thin structure to an extended volume in an object 2 based on a virtual three-dimensional object model M by solidifying a powder using radiation. The device 34 comprises a detection unit 36, a manufacturing mode unit 37, and a modification unit 38.

[0082] The investigation unit 36 ​​serves to determine a number of connection points A in the object model M at which a structure W with a thickness below a specified limit value connects to a volume boundary B whose thickness exceeds a specified limit value.

[0083] The manufacturing mode unit 37 serves to specify a manufacturing mode F for a number of determined connection points A such that for a connection point A of a structure W to a volume boundary B the contact area between structure W and volume boundary B is increased and / or a manufacturing sequence is specified according to which the structure W is manufactured before or with the corresponding volume boundary B.

[0084] The modification unit 38 is used to modify the object model M, for example, if geometries have been changed or if the object model M contains information on the manufacturing sequence or radiation parameters. Alternatively or additionally, it is used to generate control data PS for the production of an object 2 from the object model M according to the specified manufacturing mode F.

[0085] In this example, the device 34 is preferably also designed to generate control data PS for the layer-by-layer construction of an object 2 based on the object model M. The device 34 does not necessarily have to be part of the control unit 30, although this is preferred. It can also be external. For example, the control unit 30 can be connected to a terminal 40 with a display or the like via a bus 60 or another data connection, as shown here. An operator can control the control unit 30 and thus the entire laser sintering device 1 via this terminal 40, e.g., by transmitting control data PS that has been generated there by a device 34 (as indicated by the dashed line).

[0086] It should also be noted again at this point that the present invention is not limited to such a manufacturing device 1. It can be applied to other methods for the generative or additive manufacturing of a three-dimensional object by layer-by-layer application and selective solidification of a build-up material, wherein an energy beam is emitted onto the build-up material to be solidified. Accordingly, the irradiation device can also be anything other than a laser, as described here, but any device could be used with which energy can be selectively introduced onto or into the build-up material as wave or particle radiation. For example, instead of a laser, another light source, an electron beam, etc., could be used.

[0087] Figure 2 shows an example of a wall (W) or strut being connected to a thin structure W and a volume boundary B, which in this case is a wall of an extended structure ("bulk"). This example lies in the XY plane, i.e., on the construction site, where a wall W would project upwards in the Z direction from the volume boundary B. However, this (as in the following figures) is merely an example. All examples shown in Figures 2 to 10 can, in principle, be positioned arbitrarily in space.

[0088] In this figure, the structure W abuts the volume boundary B at a connection point A.

[0089] Figure 3 illustrates problems encountered when connecting a wall (W) or strut as an example of a thin structure W to a volume boundary B, as shown in Figure 2. The top section depicts a situation where, during the fabrication of the volume element B, the melt pulled powder away from the connection point A. Consequently, insufficient build material was available at this point during the fabrication of the structure W, resulting in a narrowing of the structure W at the connection point A.

[0090] In the lower illustration, the melt also contracted unintentionally during cooling, so that the volume boundary B is slightly bent inwards. In addition to the narrowing of the structure W, it no longer aligns with the volume boundary B at all.

[0091] Figure 4 shows a preferred procedure within the framework of the inventive method. Here, the structure W is fabricated first (above, where sufficient build material is available) and only then the volume boundary B. In addition, the structure W is extended so that it slightly overlaps the volume boundary B. Thus, both problems in Figure 3 are effectively counteracted.

[0092] Figure 5 shows a preferred, thickened connection of a structure W to a volume boundary B. The thickening is trumpet-shaped and additionally stiffens the connection area A. Here, the thickening is designed as part of the volume boundary B and overlaps with the structure W. However, it can also be designed as part of the structure W and, if necessary, extend into the volume boundary B. Ultimately, the edge of the volume boundary B could also merge into the structure W. Figure 6 shows another preferred thickened connection of a structure W to a volume boundary B in the form of two additional reinforcement structures that extend into the volume boundary B.

[0093] Figure 7 shows a preferred manufacturing mode in which the irradiation device 20 operates with a continuous beam at the connection point A and operates in pulse mode for the remaining solidification of the structure W.

[0094] Figure 8 shows another preferred connection of a structure W to two superimposed volume boundaries B. The structure W overlaps both volume boundaries B.

[0095] Figure 9 shows an oblique coupling of a structure W to a volume boundary B at an angle α. In this case, the structure W exhibits a thickening only at the volume boundary B. Such a one-sided thickening is advantageous because it leaves the outer side of the structure W smooth.

[0096] Figure 10 shows an interlocking of structure W with volume boundary B, whereby the extended part of structure W, which projects into volume boundary B, becomes thicker with increasing penetration depth. This interlocking mechanism can, of course, also be implemented for an oblique coupling of the structure.

[0097] Figure 11 shows a block diagram of the method for improving the connection of a wall (W) or strut as an example of a thin structure (W) to an extended volume in a layer-by-layer manufactured object 2 based on a virtual three-dimensional object model M by solidifying a powdered build-up material by means of radiation.

[0098] In step I, a number of connection points A in the object model M are determined, at which a structure W with a thickness below a specified limit is connected to a volume boundary B (thick wall or side surface) whose thickness exceeds a specified limit.

[0099] In step II, a manufacturing mode F is specified for a number of determined connection points A such that, for a connection point A of a structure W to a volume boundary B, the contact area between structure W and volume boundary B is increased and / or a profile of beam parameters for the manufacturing of the structure W is specified and / or a manufacturing sequence is specified according to which the structure W is manufactured before or together with the corresponding volume boundary B.

[0100] In step III, control data PS for the production of an object 2 from the object model M is generated according to the specified production mode F.

[0101] Figure 12 shows a more detailed diagram for a preferred method. In step S1, an object model M is conceptualized and designed. This is then created and saved in step S2 using a CAD program. The object model M can be a solid model with thin structures of small extent, or a solid model combined with, or at least partially created from, surface elements, where the surface elements describe the thin structures.

[0102] In step S3, connection points A are determined in the object model M where a structure W with a thickness below a predefined limit connects to a volume boundary B whose thickness exceeds a predefined limit. This can be done in a 3D object model M or in an object model M that has already been decomposed into layers.

[0103] Step S4 prompts the user to choose between manual and automatic geometry adjustment. This step may be preceded by a query asking whether any adjustment is desired at all. If manual adjustment is chosen, the user can perform it directly in the CAD program. This could involve selecting the connection points A in the CAD program. Afterward, step S3 could be repeated (as indicated here), or the process could proceed directly to manufacturing. If automatic adjustment is desired, the process continues with step S5.

[0104] In step S5, the contact area between structure W and volume boundary B is automatically increased for the connection points A, and / or a profile of beam parameters for the fabrication of structure W is specified, and / or a fabrication sequence is specified according to which structure W is fabricated before or together with the corresponding volume boundary B. This is done according to a predefined fabrication mode F. Thus, for example, beam parameters can be adjusted for some of the connections A, thickenings can be performed for another part of the connection points A, and fabrication sequences can be specified for yet another part.

[0105] In step S6, control commands PS are generated to build an object 2 according to the object model M, taking into account the modifications in step S5, and a final setup of the manufacturing device 1 is performed if necessary. Alternatively, the object model M can be modified according to the modifications in step S5 and then divided into manufacturing layers.

[0106] In step S7, the manufacturing of object 2 then takes place.

[0107] Finally, it should be noted once again that the invention described in detail above merely represents exemplary embodiments, which can be modified in various ways by a person skilled in the art without departing from the scope of the invention. Furthermore, the use of the indefinite articles "a" or "an" does not preclude the possibility that the features in question may be present multiple times. Likewise, terms such as "unit" do not preclude the possibility that the components in question consist of several interacting sub-components, which may also be spatially distributed. The term "a number" should be interpreted as "at least one."

[0108] Reference symbol list

[0109] 1 Device for additive manufacturing / manufacturing device

[0110] 2 Component / Object

[0111] 3 Process room / Process chamber

[0112] 4 chamber wall

[0113] 5 containers

[0114] 6 Container wall

[0115] 7 Working level

[0116] 8 Building plot

[0117] 10 carriers

[0118] 11 Base plate

[0119] 12 building platforms

[0120] 13 Construction material (in container 5)

[0121] 14 storage containers

[0122] 15 assembly material (in storage container 14)

[0123] 16 coaters

[0124] 17 Radiant heating

[0125] 20 Irradiation device / Exposure device

[0126] 21 lasers

[0127] 22 Laser beam / energy beam

[0128] 23 Deflection device / Scanner

[0129] 24 Focusing device

[0130] 25 coupling windows

[0131] 29 Control unit

[0132] 30 Control unit

[0133] 31 Irradiation control interface

[0134] 34 Device

[0135] 35 Data interface

[0136] 36 Investigation Unit

[0137] 37 Manufacturing Mode Unit

[0138] 38 Change Unit

[0139] 40 Terminal

[0140] 60 Bus

[0141] A connection point

[0142] B Volume limitation F Manufacturing mode

[0143] H horizontal direction

[0144] HS heating control data

[0145] M Object model PS Process control data / Control data

[0146] S1 - S7 process steps

[0147] Sl layer information

[0148] ST coating control data

[0149] TS T carrier control data V vertical direction

[0150] W wall / structure at an angle

[0151] I - III Procedural Steps

Claims

Patent claims 1. Method for improving the attachment of a thin structure (W) to an extended volume in a layer-by-layer manufactured object (2) based on a virtual three-dimensional object model (M) by solidifying a powdered build-up material by means of radiation, the method comprising the steps: - Determine a number of connection points (A) in the object model (M) where a structure (W) with a thickness below a given limit connects to a volume boundary (B) whose thickness exceeds a given limit, - Specifying a manufacturing mode (F) for a number of identified connection points (A) such that for a connection point (A) of a structure (W) to a volume boundary (B) the contact area between structure (W) and volume boundary (B) is increased and / or a profile of beam parameters for the manufacturing of the structure (W) is specified and / or a manufacturing sequence is specified according to which the structure (W) is manufactured before or together with the corresponding volume boundary (B), - Modifying the object model (M) and / or generating control data (PS) to manufacture an object (2) from the object model (M) according to the specified manufacturing mode (F).

2. Method according to claim 1, wherein a connection point (A) is determined by searching the object model (M) for walls with a thickness below the predetermined limit value and for a contact area of ​​these walls with volume boundaries (B) of the object model (M), preferably wherein a contact area is considered a connection point (A) only if the structure (W) extends in a predetermined angular range around the surface normal of the volume boundary (B).

3. Method according to one of the preceding claims, wherein the manufacturing mode (F) modifies the connection point (A) such that the structure (W) is extended into the volume boundary (B) for a predetermined distance, preferably longer than 0.1 mm, but preferably shorter than 5 mm or preferably for a predetermined multiple of the thickness of the structure (W), preferably wherein the extended part is thicker than the structure (W) and / or becomes thicker with increasing penetration depth.

4. Method according to one of the preceding claims, wherein the manufacturing mode (F) determines that the connection point (A) is thickened in a predetermined area in front of the volume limitation (B), preferably wherein - Structures are added that run parallel to and touch the structure (W), - the structure (W) is widened there in parallel or - a conical or trumpet-shaped transition is formed between structure (W) and volume boundary (B).

5. A method according to any of the preceding claims, wherein the manufacturing mode (F) determines that at the connection point (A) the structure (W) is manufactured with different beam parameters than other areas of the structure (W), wherein at the connection point (A) the structure (W) is preferably manufactured with a higher power and / or a larger beam diameter, preferably wherein compared to the manufacturing of the rest of the structure (W) at the connection point (A) - the power of continuous radiation is higher, and / or - the beam duration of pulsed radiation is higher, and / or - a higher energy input occurs, and / or - a different energy distribution is used at the radiation point, and / or - a larger radiation point is used.

6. Method according to one of the preceding claims, wherein the connection point (A) is formed as part of the volume boundary (B), preferably together with a part of the structure (W), wherein preferably solidification vectors for manufacturing the volume boundary (B) are designed such that they form the connection point (A) and preferably also a part of the structure (W).

7. Method according to one of the preceding claims, wherein the manufacturing mode (F) is additionally designed such that it specifies a local thickening of the volume boundary (B) in the area of ​​the connection point (A).

8. A method according to one of the preceding claims, wherein, prior to determining a number of connection points (A) in the object model (M), a conception and design of the object model M is carried out and its creation is performed, preferably using a CAD program, wherein connection points A are determined in 2D layers of a layered object model M or in a 3D object model M. and preferably asks whether a manual or an automatic adjustment should be made.

9. Tax data (PS) that have been created using a method according to any of the preceding claims.

10. Device (34) for improving the connection of a thin structure (W) to an extended volume in a layer-by-layer manufactured object (2) based on a virtual three-dimensional object model (M) by solidifying a powdered build-up material by means of radiation, the method comprising: - a determination unit (36) designed to determine a number of connection points (A) in the object model (M) at which a structure (W) with a thickness below a specified limit value connects to a volume boundary (B) whose thickness exceeds a specified limit value, - a manufacturing mode unit (37) designed to specify a manufacturing mode (F) for a number of identified connection points (A) such that for a connection point (A) of a structure (W) to a volume boundary (B) the contact area between structure (W) and volume boundary (B) is increased and / or a manufacturing sequence is specified according to which the structure (W) is manufactured before or with the corresponding volume boundary (B), - a modification unit (38) designed to modify the object model (M) and / or generate control data (PS) for the manufacture of an object (2) from the object model (M) according to the specified manufacturing mode (F).

11. Manufacturing device (1) designed to carry out a manufacturing process in which an object (2) is built up based on a virtual three-dimensional object model (M) by layer-by-layer solidification of a powdered build-up material by means of radiation, comprising a control device (30) for controlling the manufacturing process and a device (34) according to claim 10.

12. Computer program product comprising a computer program which can be directly loaded into a storage device of a computer unit, in particular a control device (30) of an additive manufacturing device (1), comprising program sections to execute all steps of the method according to any one of claims 1 to 8 when the computer program is executed in the computer unit.

13. Computer-readable storage medium comprising instructions which, when executed by a computer, cause the computer to perform the steps of the method according to claims 1 to 8.

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