METHOD FOR THE ADDITIVE MANUFACTURING OF A THREE-DIMENSIONAL OBJECT

Description

[0001] The invention relates to a method for the additive production of a three-dimensional object by successive layer-by-layer selective exposure and the associated successive layer-by-layer selective solidification of building material layers from a building material that can be solidified by means of an energy beam.

[0002] Corresponding processes for the additive manufacturing of three-dimensional objects are generally known. A well-known example of such a process is selective laser melting, or SLM for short.

[0003] Within the scope of implementing corresponding methods, it is also known to form support structures. Corresponding support structures are characterized by a supporting effect for respective additively manufactured or produced three-dimensional objects and typically comprise a plurality of strut-like or strut-shaped support elements. Thus, respective additively manufactured or produced three-dimensional objects are supported by corresponding support structures. Corresponding support structures are typically removed from the respective additively manufactured three-dimensional object after completion of the additive construction process.

[0004] Particularly in the additive manufacturing of three-dimensional objects with delicate or complex geometric-constructive shapes, it is sometimes difficult to form support structures which, on the one hand, provide sufficient support even in hard-to-reach areas, e.g., undercut areas of a respective three-dimensional object, and, on the other hand, can be removed without damaging the respective three-dimensional object.

[0005] FR 2 974 316 A1 discloses a principle for forming a support structure for an additively manufactured or produced object.

[0006] JAMASP JHABVALA ET AL: "An innovative method to build support structures with a pulsed laser in the selective laser melting process" (THE INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY, SPRINGER, BERLIN, DE) describes the production of a part from stainless steel powder and a watch clasp from silver powder and a manufacturing process for the additive manufacturing of a part by means of laser melting, in which a support structure is also built.

[0007] The invention is based on the object of providing an improved method for the additive production of a three-dimensional object, in particular with regard to the realization of a support structure which is improved compared to the prior art.

[0008] The object is achieved by a method for the additive production of a three-dimensional object according to claim 1. The dependent claims relate to possible embodiments of the method.

[0009] The method described herein serves for the additive manufacturing of three-dimensional objects, i.e., for example, technical components or groups of technical components, by successive layer-by-layer selective exposure and the associated layer-by-layer selective solidification of building material layers made of a solidifiable building material. The building material is a powdered metal, plastic, and / or ceramic material. The successive layer-by-layer selective exposure or solidification of the respective building material layers to be selectively solidified is carried out on the basis of object-specific construction data. Corresponding construction data describe the geometric-constructive shape of the respective object to be additively manufactured and can, for example, contain "sliced" CAD data of the object to be additively manufactured. According to the invention, the method is implemented as a selective laser melting process (SLM process) or as a selective laser sintering process (SLS process).

[0010] According to the method, within the framework of the additive manufacturing of a respective three-dimensional object to be additively manufactured – hereinafter referred to as "object" for short – this involves, in addition to the additive construction or additive formation of the respective object actually to be manufactured, an additive construction or additive formation of a support structure also takes place. The support structure supports the respective object at least in sections; the support structure thus exerts a supporting effect on the respective object at least in sections.

[0011] The support structure formed according to the method directly surrounds a respective object, i.e., individual, multiple, or all object sections of the respective object. In other words, the respective object is embedded in the support structure at least in sections, in particular completely. Thus, there is at least in sections, in particular completely, direct mechanical contact between the support structure and the respective object to be supported or supported.

[0012] It is conceivable that the support structure surrounds the respective object at least in sections, e.g., with several contiguous or non-contiguous support structure sections, or that the support structure completely surrounds the respective object, e.g., with several contiguous or non-contiguous support structure sections. The support structure can thus be formed with several contiguous or non-contiguous support structure sections or comprise several contiguous or non-contiguous support structure sections. Corresponding support structure sections extend, at least in sections, along the respective object, surrounding it.

[0013] As mentioned, the support structure is formed during the additive manufacturing of the respective object. According to the process, the support structure is formed by successive layer-by-layer selective exposure and the associated successive layer-by-layer selective pre-consolidation of building material layers from the building material that can be solidified by the energy beam. The successive layer-by-layer selective exposure or pre-consolidation of the respective building material layers to be selectively solidified is carried out based on support structure-related construction data. Corresponding construction data describe the geometric-structural shape of the respective support structure to be additively manufactured and can, for example, include "sliced" CAD data of the support structure to be additively manufactured.

[0014] It is essential that the formation of the support structure occurs through pre-consolidation of the building material. Pre-consolidation is to be understood as a slight(er) solidification of the building material, particularly in comparison to the solidification of the building material for the formation of the actual object to be manufactured. The pre-consolidation implemented for the formation of the support structure differs from the solidification implemented for the formation of an actual object to be manufactured in the respective degree of solidification achieved. To form the support structure, the building material is solidified (significantly) less - as will be seen below, the building material is typically not completely melted - than for the formation of the actual object to be manufactured, which can be achieved, for example, by using different, i.e.in particular, different powerful exposure devices and / or different exposure parameters, in particular through a lower exposure intensity, shorter exposure time, etc. The different degrees of solidification also result in different structural, i.e. in particular mechanical, properties between the support structure and the actual manufactured object; typically, the support structure has, for example, a (significantly) lower density and a (significantly) lower strength than the respective object.

[0015] Because the support structure directly surrounds the respective object (at least in sections) or the respective object (at least in sections) is embedded (precisely) in the support structure, the support structure provides sufficient support even in hard-to-reach areas, e.g., undercut areas (if present) of the respective object. Because the support structure is formed by pre-consolidating the building material, it can be removed from the respective object without difficulty, i.e., in particular, without damaging the respective object. Overall, this represents an improved process for the additive manufacturing of three-dimensional objects.

[0016] It was mentioned that the pre-consolidation to form the support structure differs from the consolidation to form the actual object to be manufactured in the respective degree of consolidation achieved. The successive layer-by-layer selective consolidation of the building material to form a respective object takes place in a first degree of consolidation of the building material, and the successive layer-by-layer selective pre-consolidation of the building material to form the support structure takes place in a second degree of consolidation of the building material, which is below the first degree of consolidation. The second degree of consolidation is typically chosen to be low so that the support structure can be removed from the respective object without difficulty, i.e. in particular without damaging the respective object. The second degree of consolidation is chosen to be so low that the support structure disintegrates of its own accord during an unpacking process for the respective object.

[0017] Specifically, the support structure can be porous, i.e., with a specific porosity, at least in sections, in particular completely. A porous support structure is generally understood to mean any delicate structure that, due to its delicate shape, can be removed from the respective object without damaging it, e.g., a sponge structure.

[0018] The successive, layer-by-layer selective solidification of the building material to form the object can be achieved, in particular, by completely melting (and subsequent cooling) the building material. The successive, layer-by-layer selective solidification of the building material to form the object typically occurs through the selective introduction of radiant energy, which heats the building material to a temperature above its melting temperature, so that the building material is melted and undergoes a phase transition (solid-liquid). In contrast, the successive, layer-by-layer selective pre-solidification of the building material to form the support structure typically does not occur through (complete) melting (and subsequent cooling) of the building material.The successive, layer-by-layer selective pre-consolidation of the building material to form the support structure is achieved by selectively introducing radiant energy, which heats the building material to a temperature below its melting point, preventing the building material from melting and thus from undergoing a phase transition (solid-liquid). Through the successive, layer-by-layer selective pre-consolidation, a sintered bond can be formed between neighboring building material particles through the formation of a sinter neck. However, the building material does not undergo a phase transition.

[0019] In order to surround the object to be manufactured or manufactured, in particular completely, the support structure can be designed with a geometric shape that (completely) surrounds the object to be manufactured or manufactured. The geometric shape of the support structure is to be selected in particular as a function of the geometric shape of the object to be manufactured or manufactured and the degree of surroundings, i.e. the degree to which the support structure is to surround the object. Accordingly, it is mentioned merely by way of example that the support structure can be designed with a cuboid-like or -shaped, possibly cube-like or -shaped, or a spherical or -shaped geometric shape. Of course, the support structure can also be designed in free, i.e. in particular not geometrically clearly defined, geometric shapes.

[0020] For example, it is possible for the support structure to be designed with a geometric shape that follows the contour, in particular the outer and / or inner contour, of the object to be manufactured or produced. The geometric shape of the support structure, which follows the contour of the object, thus essentially corresponds - apart from a certain allowance - to the geometric shape of the object to be manufactured or produced. By designing the support structure with a geometric shape that follows the contour of the object to be manufactured or produced, the amount of construction material used to form the support structure can be kept comparatively small.

[0021] It was mentioned that the successive, layer-by-layer selective exposure or pre-consolidation of the respective building material layers to be selectively consolidated to form the respective objects is carried out on the basis of object-specific construction data. It was further mentioned that the successive, layer-by-layer selective exposure or pre-consolidation of the respective building material layers to be selectively consolidated to form the support structure is carried out on the basis of support-structure-specific construction data. In order to keep the effort, particularly the computational effort, required to generate the support-structure-specific construction data to a minimum, the support-structure-specific construction data can be generated on the basis of the respective object-specific construction data. This equally ensures that the support structure or the supporting effect is formed taking into account the geometric shape of the respective object (section) to be supported.

[0022] The invention further relates to a device for the additive production of three-dimensional objects by successive layer-by-layer selective exposure and the associated successive layer-by-layer selective solidification of building material layers from a building material that can be solidified by means of an energy beam. The device is designed as an SLM device, i.e., as a device for carrying out selective laser melting processes (SLM processes), or as an SLS device, i.e., as a device for carrying out selective laser sintering processes (SLS processes). The device is characterized in that it is configured to carry out the described method. Therefore, all statements relating to the method apply analogously to the device.

[0023] The device comprises the functional components typically required to carry out additive building processes. These include, in particular, a coating device which is designed to form build material layers to be selectively solidified (in the build plane of the device), and an exposure device which is designed to selectively expose build material layers to be selectively solidified (in the build plane of the device). The coating device typically comprises several components, e.g. a coating element comprising a, in particular blade-shaped, coating tool, and a guide device for guiding the coating element along a defined movement path. The exposure device also typically comprises several components, e.g. a beam generation device for generating an energy orLaser beam, a beam deflection device (scanner device) for deflecting an energy or laser beam generated by the beam generation device onto an area to be exposed of a building material layer to be selectively solidified, as well as various optical elements, such as lens elements, objective elements, etc.

[0024] The invention is explained in more detail using exemplary embodiments in the drawing figures. In the drawings: Fig. 1 shows a schematic diagram of a device according to an embodiment; and Figs. 2 and 3 each show a schematic diagram of a support structure according to an embodiment.

[0025] Fig. 1 shows a schematic diagram of a device 1 according to an embodiment.

[0026] The device 1 is used for the additive production of three-dimensional objects 2, ie in particular technical components or technical component groups, by successive layer-by-layer selective exposure and associated successive layer-by-layer selective solidification of building material layers made of a solidifiable building material 3, e.g. a metal powder, by means of an energy or laser beam 4. The device 1 can be designed as a Laser-CUSING ®< device, ie as a device for carrying out selective laser melting processes.

[0027] The device 1 comprises the functional components required to carry out additive construction processes; in Fig. 1 For example, a coating device 5 and an exposure device 6 are shown.

[0028] The coating device 5 is configured to form build material layers that are to be selectively exposed or selectively solidified in a build plane of the device 1. The coating device 5 comprises a coating element assembly (not further designated) comprising a plurality of coating elements (not shown), which is mounted via a guide device (not shown) for movement in a horizontal direction, as indicated by the double arrow P1.

[0029] The exposure device 6 is configured for the selective exposure of build material layers to be selectively solidified in the build plane of the device 1 and for this purpose comprises a beam generating device (not shown) configured to generate a laser beam 4, optionally a beam deflection device (not shown) configured to deflect a laser beam 4 generated by the beam generating device onto a region of a build material layer to be selectively solidified that is to be exposed, as well as various optical elements, such as filter elements, objective elements, lens elements, etc.

[0030] In Fig. 1 Also shown are a dosing module 7, a construction module 8, and an overflow module 9, which are docked to a lower region of an interchangeable process chamber 10 of the device 1. These modules can also form a lower region of the process chamber 10.

[0031] The device 1 can be used to implement a method for the additive manufacturing of three-dimensional objects 2 by successive layer-by-layer selective exposure and the associated layer-by-layer selective solidification of building material layers made of a solidifiable building material 3. The successive layer-by-layer selective exposure or solidification of the respective building material layers to be selectively solidified is carried out on the basis of object-specific construction data. Corresponding construction data describe the geometric-constructive shape of the respective object 2 to be additively manufactured and can, for example, contain "sliced" CAD data of the object 2 to be additively manufactured. The method can be a LaserCUSING® process, i.e., a selective laser melting process.

[0032] According to the method, within the framework of the additive production of a respective object 2 to be additively produced, i.e. in addition to the additive construction or additive formation of a respective object 2 actually to be produced, an additive construction or additive formation of a support structure 11 also takes place. The support structure 11 supports the respective object 2 at least in sections, thus the support structure 11 exerts a supporting effect acting on the respective object 2 at least in sections.

[0033] Embodiments of a support structure 11 are shown in the Fig. 2, 3 shown in a schematic diagram. Object 2 is shown in the Fig. 2, 3 As an example, a filigree cube-like framework construction is shown, consisting of individual strut-like object sections arranged or aligned along the edges of an imaginary cube.

[0034] Based on the Fig. 2, 3 It can be seen that the support structure 11 directly surrounds a respective object 2, i.e., individual, several, or all object sections of the respective object 2. In other words, the object 2 is embedded (with a precise fit) in the support structure 11. There is therefore direct mechanical contact between the support structure 11 and the respective object 2 to be supported or supported. For this purpose, the support structure 11 can be formed with several contiguous or several non-contiguous support structure sections or can comprise several contiguous or several non-contiguous support structure sections. Corresponding support structure sections extend at least partially along the respective object 2, surrounding it in each case at least partially.

[0035] As mentioned, the support structure 11 is formed during the additive manufacturing of the respective object 2. According to the process, the support structure 11 is formed by successive layer-by-layer selective exposure and the associated successive layer-by-layer selective pre-consolidation of building material layers from the building material 3 that can be solidified by means of the energy beam 4. The successive layer-by-layer selective exposure or pre-consolidation of the respective building material layers to be selectively solidified is carried out on the basis of support structure-related construction data. Corresponding construction data describe the geometric-structural shape of the respective support structure to be additively manufactured and can, for example, include "sliced" CAD data of the support structure 11 to be additively manufactured.In order to minimize the effort, particularly the computational effort, required to generate the support structure-related construction data, the support structure-related construction data can be generated based on the respective object-related construction data. This also ensures that the support structure 11 is always designed taking into account the geometric shape of the respective object 2 to be supported.

[0036] It is essential that the formation of the support structure 11 occurs through a pre-consolidation of the building material 3. Pre-consolidation is to be understood as a slight(er) solidification of the building material 3, particularly compared to the solidification of the building material 3 for forming the object 2 actually to be manufactured. The pre-consolidation implemented for forming the support structure 11 therefore differs from the solidification implemented for forming the object 2 actually to be manufactured in the respective degree of solidification achieved. To form the support structure 11, the building material 3 is solidified (significantly) less than to form the object 2 actually to be manufactured, which is achieved, for example, by using different exposure devices and / or different exposure parameters, in particular by a lower exposure intensity, shorter exposure time, etc.The different degrees of solidification also result in different structural, i.e., in particular mechanical, properties between the support structure 11 and the actually manufactured object 2; for example, the support structure 11 has a (significantly) lower density and a (significantly) lower strength than the respective object 2.

[0037] The successive layer-by-layer selective solidification of the building material 3 to form the object 2 takes place in a first degree of solidification of the building material 3 and the successive layer-by-layer selective pre-solidification of the building material 3 to form the support structure 11 takes place in a second degree of solidification of the building material 3 that is below the first degree of solidification. The second degree of solidification is selected to be low so that the support structure 11 can be removed from the object 2 without problems, i.e. in particular without damaging the object 2. The second degree of solidification is selected to be so low that the support structure 11 disintegrates by itself during an unpacking process of the object 2.

[0038] The successive, layer-by-layer selective solidification of the building material 3 to form the object 2 occurs through complete melting (and subsequent cooling) of the building material 3. The successive, layer-by-layer selective solidification of the building material 3 to form the object thus occurs through the selective introduction of radiant energy, which heats the building material 3 to a temperature above its melting temperature, so that the building material 3 is melted. The building material 3 undergoes a phase transition. In contrast, the successive, layer-by-layer selective pre-solidification of the building material 3 to form the support structure 11 does not occur through (complete) melting (and subsequent cooling) of the building material 3.The successive, layer-by-layer, selective pre-consolidation of the building material 3 to form the support structure 11 is achieved by selectively introducing radiant energy, which heats the building material 3 to a temperature below its melting temperature, which may allow a sintered connection between adjacent building material particles through the formation of a sinter neck. However, the building material 3 does not undergo a phase transition.

[0039] To realize correspondingly fragile properties of the support structure 11, the support structure 11 can be designed to be porous, i.e., with a specific porosity, at least in sections, in particular completely. Specifically, the support structure 11 can be designed, for example, as a sponge structure ("sponge support").

[0040] Because the support structure 11 directly surrounds the object 2 or the object 2 is embedded in the support structure 11, the support structure 11 provides sufficient support even in hard-to-reach areas, e.g., undercut areas (if present) of the object 2. Because the support structure 11 is formed by pre-consolidating the building material 3, it can be removed from the object 2 without difficulty, i.e., in particular, without damaging the object 2.

[0041] In order to surround the object 2 to be produced or produced, the support structure 11 can be arranged as in Fig. 2 shown with a geometric shape that (completely) surrounds the object 2. The geometric shape of the support structure 2 is selected depending on the geometric shape of the object 2 and the degree of surrounding, ie the degree to which the support structure 11 is to surround the object 2. In the Fig. 2 In the embodiment shown, the support structure 11 is formed with a cuboid or cuboid-shaped, possibly cube-like or cube-shaped configuration. The object 2 is clearly arranged within the support structure 11, and the support structure 11 completely surrounds the object 2. In particular, each strut-like object section is directly surrounded by the support structure 11.

[0042] The same result could be achieved with a support structure 11 having, for example, a spherical or spherical geometric shape. The spherical or spherical geometric shape of the support structure 11 would be dimensioned such that it completely surrounds the object 2. In principle, the support structure 11 can also be formed in free, i.e., in particular, non-geometrically clearly defined, geometric shapes.

[0043] In the Fig. 3 The exemplary embodiment shown shows that the support structure 11 can also be designed with a geometric shape following the contour, in particular the outer and / or inner contour, of the object 2. The geometric shape of the support structure 11 following the contour of the object 2 thus corresponds - apart from a certain allowance - essentially to the geometric shape of the object 2. In the exemplary embodiment shown in Fig. 3 In the embodiment shown, the support structure 11 also has the geometric shape of a filigree, cube-like framework construction, consisting of individual (hollow) strut-like support structure sections arranged or aligned along the edges of an imaginary cube. The (hollow) strut-like support structure sections completely surround the strut-like object sections assigned to them.

[0044] Because the support structure 11 is formed with a geometric shape following the contour of the object 2, the amount of building material 3 used to form the support structure 11 can be kept comparatively small.

Claims

1. Method for the additive production of a three-dimensional object (2) by successively layer-wise selective exposure and associated successively layer-wise selective solidification of building material layers from a by means of an energy beam (4) solidifiable powder-like building material (3) using a selective laser melting method (SLM method) or a selective laser sintering method (SLS method), wherein in the context of the additive production of the additively produced three-dimensional object (2) a the additively produced or three-dimensional object (2) directly surrounding support structure (11) is formed by successively layer-wise selective exposure and associated successively layer-wise selective pre-solidification of building material layers from the by means of the energy beam (4) solidifiable building material (3), wherein the successive layer-by-layer selective solidification of the building material (3) for the formation of the three-dimensional object (2) takes place in a first degree of solidification of the building material (3) and the successive layer-by-layer selective pre-solidification of the building material (3) for the formation of the supporting structure (11) takes place in a second degree of solidification of the building material (3) below the first degree of solidification, wherein the successive layer-by-layer selective pre-solidification of the building material (3) for the formation of the supporting structure (11) is carried out by selective introduction of radiation energy, which heats the building material (3) to a temperature below its melting temperature, characterized in that the second degree of solidification of the building material (3) is chosen low, so that the support structure (11) disintegrates by itself during a unpacking process of the additively produced three-dimensional object (2), wherein the support structure (11) the additively manufactured or manufactured three-dimensional object (2) is formed completely surrounding.

2. Method of claim 1, characterized in that the support structure (11) is at least partially porous.

3. Method according to claim 1 or 2, characterized in that the successive layer-by-layer selective solidification of the building material (3) for forming the three-dimensional object (2) by a complete melting and subsequent cooling of the building material (3) takes place and the successive layer-by-layer selective pre-solidification of the building material (3) for forming the support structure does not take place by a complete melting and subsequent cooling of the building material (3).

4. Method according to one of the preceding claims, characterized in that the support structure (11) is formed with several contiguous or several non-contiguous support structure sections.

5. Method according to one of the preceding claims, characterized in that the support structure (11) is formed with a three-dimensional object (2) surrounding the additively manufactured or three-dimensional geometric shape or the support structure (11) is formed with one of the contour, in particular the outer and / or inner contour, of the additively manufactured or three-dimensional object (2) following geometric shape.

6. Method according to one of the preceding claims, characterized in that the successive layer-by-layer selective exposure and the associated successive layer-by-layer selective pre-solidification of building material layers from the solidifiable by means of the energy beam building material (3) is carried out on the basis of support structure-related building data, wherein the support structure-related building data are generated on the basis of object-related building data.