METHOD FOR ADDITIVELY MANUFACTURING AT LEAST ONE THREE-DIMENSIONAL OBJECT

Abstract

Method for additively manufacturing at least one three-dimensional object (2) by means of successive layerwise selective irradiation and consolidation of build material layers (3), whereby each build material layer (3) which is selectively irradiated and consolidated comprises at least one irradiation area (IA) which is irradiated and consolidated by means of at least one energy beam (5), wherein the irradiation area (IA) comprises at least one first sub-area (SA1) having a first heat conductance capability defined by its orientation and/or position relative to non-consolidated build material areas adjacent to the irradiation area (IA) and at least one second sub-area (SA2) having a second heat conductance capability higher than the first heat conductance capability of the first sub-area (SA1) defined by its orientation and/or position relative to non-consolidated build material areas adjacent to the irradiation area (IA), whereby for at least one irradiation area of at least one build material layer (3) which is to be selectively irradiated and consolidated a respective first sub-area (SA1) is irradiated before a respective second sub-area (SA2).

Claims

1. Method for additively manufacturing at least one three-dimensional object (2) by means of successive layerwise selective irradiation and consolidation of build material layers (3), whereby each build material layer (3) which is selectively irradiated and consolidated comprises at least one irradiation area (IA) which is irradiated and consolidated by means of at least one energy beam (5), wherein the irradiation area (IA) comprises at least one first sub-area (SA1) having a first heat conductance capability defined by its orientation and/or position relative to non-consolidated build material areas adjacent to the irradiation area (IA) and at least one second sub-area (SA2) having a second heat conductance capability higher than the first heat conductance capability of the first sub-area (SA1) defined by its orientation and/or position relative to non-consolidated build material areas adjacent to the irradiation area (IA), whereby for at least one irradiation area of at least one build material layer (3) which is to be selectively irradiated and consolidated a respective first sub-area (SA1) is irradiated before a respective second sub-area (SA2).

2. Method according to claim 1, wherein the thermal energy input into the at least one irradiation area (IA) by the at least one energy beam (5) is directed from the at least one first sub-area (SA1) towards the at least one second sub-area (SA2), particularly such that the thermal energy input into the at least one irradiation area (IA) is directed from the at least one first sub-area (SA1) towards the center (C) or a center region of the at least one irradiation area (IA).

3. Method according to claim 1, wherein the at least one first sub-area (SA1) is at least partially, particularly completely, located above a non-irradiated and non-consolidated irradiation area of a preceding build material layer (3) and/or the at least one second sub-area (SA2) is at least partially, particularly completely, located above an irradiated and consolidated build material area of a preceding build material layer (3).

4. Method according to claim 3, wherein the at least one first sub-area (SA1) is or comprises an overhang region of the three-dimensional object (2) which is to be additively manufactured.

5. Method according to claim 1, wherein the at least one first sub-area (SA1) is built by or comprises a border region of the at least one irradiation area (IA) with respect to a non-consolidated build material area at least partially adjacent to the at least one irradiation area (IA) in a respective build material layer (3) and the at least one second sub-area (SA2) is built by or comprises a non-border region of the irradiation area (IA) with respect to the non-consolidated build material area at least partially adjacent to the at least one irradiation area (IA) in the respective build material layer (3).

6. Method according to claim 1, wherein the at least one irradiation area (IA) is irradiated on basis of an irradiation pattern (IP) comprising a plurality of irradiation vectors (IV), whereby an irradiation vector (IV) or at least one section of an irradiation vector extending in the at least one first sub-area (SA1) are irradiated before an irradiation vector (IV) or at least one section of an irradiation vector extending in the at least one second sub-area (SA2).

7. Method according to claim 1, wherein the at least one irradiation area (IA) comprises at least two irradiation area segments (IAS1-IAS8) which are separately irradiatable or irradiated with at least one energy beam (5), whereby each irradiation area segment (IAS1-IAS8) comprises at least one first sub-area (SA1) having a first heat conductance capability and at least one second sub-area (SA2) having a second heat conductance capability higher than the first heat conductance capability, whereby the or at least one first sub-area (SA1) of a respective irradiation area segment (IAS1-IAS8) are irradiated before at least one respective second sub-area (SA2) of the respective irradiation area segment (IAS1-IAS8).

8. Method according to claim 1, wherein the at least one first sub-area (SA1) or a respective irradiation area segment (IAS1-IAS8) surrounds the at least one second sub-area (SA2) a respective irradiation area segment (IAS1-IAS8).

9. Method according to claim 1, wherein the at least one irradiation area (IA) is irradiated on basis of an irradiation pattern (IP) comprising a plurality of irradiation vectors (IV), whereby at least one pattern parameter, in particular the orientation of at least one irradiation vector (IV), of the irradiation pattern (IP) of a at least one irradiation area (IA) of a first build material layer (3) which is to be selectively irradiated and consolidated is changed with respect to at least one pattern parameter of at least one second irradiation pattern (IP) of a second build material layer (3) which is to be selectively irradiated and consolidated.

10. Method according to claim 1, wherein the irradiation pattern (IP) is a stripe-pattern, a chessboard-pattern, or an island-pattern.

11. Control unit (7) for an apparatus (1) for additively manufacturing at least one three-dimensional object (2) by means of successive layerwise selective irradiation and consolidation of build material layers (3), whereby each build material layer (3) comprises at least one irradiation area (IA) which is to be irradiated and consolidated by means of at least one energy beam (5), whereby the at least one irradiation area (IA) comprises at least one first sub-area (SA1) having a first heat conductance capability defined by its orientation and/or position relative to non-consolidated build material areas adjacent to the irradiation area (IA) and at least one second sub-area (SA2) having a second heat conductance capability defined by its orientation and/or position relative to non-consolidated build material areas adjacent to the irradiation area (IA) higher than the first heat conductance capability defined by its orientation and/or position relative to non-consolidated build material areas adjacent to the irradiation area (IA) of the first sub-area (SA1), wherein the control unit (7) is configured to control the successive layerwise selective irradiation and consolidation of respective irradiation areas (IA) in accordance with the method according to claim 1.

12. Apparatus (1) for additively manufacturing at least one three-dimensional object (2) by means of successive layerwise selective irradiation and consolidation of build material layers (3), whereby each build material layer (3) comprises at least one irradiation area (IA) which is to be irradiated and consolidated by means of at least one energy beam (5), the apparatus (1) comprising a control unit (7) according to claim 11.

Description

[0033] Exemplary embodiments of the invention are described with reference to the Fig., whereby:

[0034] FIG. 1 shows a principle drawing of an apparatus for additively manufacturing of three-dimensional objects according to an exemplary embodiment in a side-view; and

[0035] FIG. 2-5 each show a principle drawing of a build material layer which is to be selectively irradiated and consolidated in accordance with a method according to an exemplary embodiment in a top-view; and

[0036] FIG. 6 shows a principle drawing of a three-dimensional object during the additive manufacturing process.

[0037] FIG. 1 shows a principle drawing of an exemplary embodiment of an apparatus 1 for additively manufacturing three-dimensional objects 2, e.g. technical components, by means of successive layerwise selective irradiation and accompanying consolidation of build material layers 3 of a powdered build material 4, e.g. a metal powder, which can be consolidated by means of at least one energy beam 5 according to an exemplary embodiment. The energy beam 5 may be an electron beam or a laser beam, for instance. The apparatus 1 may be embodied as a selective electron beam melting apparatus or as a selective laser melting apparatus, for instance.

[0038] The apparatus 1 comprises a number of functional and/or structural units which are operable and operated during its operation. Each functional and/or structural unit may comprise a number of functional and/or structural sub-units. Operation of the functional and/or structural units and the apparatus 1, respectively is controlled by a hard- and/or software embodied (central) control unit 6.

[0039] Exemplary functional and/or structural units of the apparatus 1 are a build material application unit 7, an irradiation unit 8, and the control unit 6. Further functional and/or structural units of the apparatus 1 may be provided even though not depicted in the Fig.

[0040] The build material application unit 7 is configured to apply an amount of build material 4 in the build plane BP of the apparatus 1 so as to successively generate respective build material layers 3 which are to be selectively irradiated and consolidated during additively manufacturing a object 2. The build material application unit 7 may comprise a build material application element 9 which may be embodied as a blade-like re-coating element, for instance. The build material application element 9 may be moveably supported within the process chamber 10 of the apparatus 1; the build material application element 9 may particularly be moved across the build plane BP so as to apply an amount of build material 4 in the build plane BP so as to generate a respective build material layer 3 which is to be selectively irradiated and consolidated during additively manufacturing a object 2. An exemplary motion of the build material application element 9 across the build plane BP is indicated by double-arrow P1. A drive unit (not shown) may be assigned to the build material application unit 7 so as to generate a drive force for moving the build material application element 9 across the build plane BP.

[0041] The irradiation unit 8 is configured to selectively irradiate and thereby, consolidate respective build material layers 3 which have been applied in the build plane BP of the apparatus 1 by means of the build material application unit 7 with at least one energy beam 5. The irradiation unit 8 may at least comprise a beam generating unit (not shown) configured to generate the at least one energy beam 5. The irradiation unit 8 may further comprise a beam deflecting unit (not shown), e.g. a scanning unit, configured to deflect the at least one energy beam 5 to diverse positions within the build plane BP.

[0042] The control unit 6 is configured to implement a method for additively manufacturing an object 2 according to exemplary embodiments which will be explained in more detail in context with FIG. 2-6.

[0043] According to exemplary embodiments of the method, each build material layer 3 which is to be selectively irradiated and consolidated comprises at least one irradiation area IA which is to be irradiated and consolidated by means of the energy beam 5 or at least on energy beam 5, respectively. A respective irradiation area IA is irradiated on basis of an irradiation pattern IP comprising a number of irradiation pattern elements IPE defined by irradiation vectors IV, e.g. scan vectors, in a specific arrangement relative to each other. The irradiation vectors IV define the path of the at least one energy beam 5 across the irradiation area IA.

[0044] FIG. 2 shows an exemplary embodiment in which a respective irradiation pattern MP may comprise a plurality of stripe-like shaped irradiation pattern elements IPE arranged in a specific parallel arrangement relative to each other. The irradiation pattern elements IPE are exemplarily arranged in a parallel arrangement.

[0045] FIG. 3 shows an exemplary embodiment in which a respective irradiation pattern MP may comprise a plurality of rectangular shaped irradiation pattern elements IPEwhich may also may be denoted as islandsarranged in a specific parallel arrangement relative to each other. The irradiation pattern elements IPE are exemplary arranged so as to form checkerboard pattern.

[0046] Generally, i.e. particularly independent from the irradiation pattern elements IPE exemplarily shown in FIG. 2, 3, respective irradiation pattern elements IPE are separately irradiatable or irradiated with at least one energy beam 5 independent of their size, shape, position and orientation. Hence, each irradiation pattern element IPE may be separately irradiated with an energy beam 5, whereby the energy beam 5 is guided across the respective irradiation pattern element IPE in a certain path defined by the irradiation vectors IV of the respective irradiation pattern element IPE.

[0047] According to the method, an irradiation area IA comprises at least one first sub-area SA1 having a first heat conductance capability defined by its orientation and/or position relative to non-consolidated build material areas adjacent to the irradiation area IA, particularly surrounding the irradiation area IA, and at least one second sub-area SA2 having a second heat conductance capability higher than the first heat conductance capability of the first sub-area SA1 defined by its orientation and/or position relative to non-consolidated build material areas adjacent to the irradiation area IA, particularly surrounding the irradiation area IA. In other words, the irradiation area IA comprises sub-areas SA1, SA2 having different heat conductance capabilities, i.e. at least one sub-area SA1 of low(er) heat conductance capability and at least one second sub-area SA2 of high(er) heat conductance capability. Typically, the first sub-areas SA1 also have a low(er) capability of heat conductance, i.e. particularly a low(er) capability of heat dissipation, compared with the second sub-areas SA2. As is apparent from the exemplary embodiment of FIG. 6, respective first sub-areas SA1 may be overhang sections of the object 2 which is to be additively manufactured, for instance.

[0048] According to the method, respective first sub-areas SA1 are irradiated before respective second sub-areas SA2. Thus, respective second sub-areas SA2 are irradiated after the first sub-areas SA1 have been (completely) irradiated. Hence, a respective irradiation area IA is first irradiated in the one or more first sub-area(s) SA1 having a comparatively low heat conductance capability and thermal energy conductance and then irradiated in the one or more second sub-area(s) SA2 having a comparatively high heat conductance capability and thermal energy conductance.

[0049] Hence, the method implements a specific order of energy beam irradiation processing and a specific order of irradiating respective first and second sub-areas SA1, SA2 of a respective irradiation area IA having sub-areas SA1, SA2 of different heat conductance capabilities and conductances according to which the first sub-area(s) SA1 having a comparatively low heat conductance capability and conductance are irradiated before the second sub-area(s) SA2 having a comparatively high heat conductance capability and conductance.

[0050] Hence, irradiation vectors IV or sections SV1, SV2 of irradiation vectors extending in a respective first sub-area SA1 are irradiated before irradiation vectors IV or sections SV1, SV2 of irradiation vectors extending in a respective second sub-area SA2. As is exemplarily apparent from FIG. 2, 3, an irradiation vector IV may comprise at least one section SV1 extending in a first sub-area SA1 and at least one section SV2 extending in a second sub-area SA2, the section(s) SV1 which extend(s) in the first sub-area(s) SA1 will be processed and irradiated before the section(s) SV2 which extend(s) in the second sub-area(s) SA2 in accordance with the method.

[0051] In such a manner, the method allows for that undesired accumulations of thermal energy (heat) particularly in respective first sub-areas SA1 can be reduced or avoided, particularly since the order of irradiation allows for that respective first sub-areas SA1 may dissipate thermal energy input during irradiation into other regions having a higher heat conductance capability and conductance, i.e. particularly in respective second sub-areas SA2. Hence, reducing or avoiding undesired accumulations of thermal energy in accordance with the method is a measure to improve the structural properties of the object 2 manufacturable with the method.

[0052] The thermal energy input into the at least one irradiation area IA by the energy beam 5 may thus, be directed from the one or more first sub-areas SA1 towards the one or more second sub-areas SA2, particularly such that the thermal energy input into an irradiation area IA is directed from the one or more first sub-area SA1 towards the center C or a center region of the respective irradiation area IA. In either case, undesired accumulations of thermal energy can be reduced or avoided. As is apparent from the Fig., the center C of a respective irradiation area IA may be defined by the geometric center of the irradiation area IA or the center of gravity of the object 2 in the respective build material layer 3. Hence, the thermal energy input into the irradiation IA area by the energy beam 5 may be directed from outer regions of the irradiation area IA towards inner or center regions of the irradiation area IA.

[0053] As is apparent from the Fig., a first sub-area SA1 may be built by or may comprise an outer region, which may also be deemed or denoted as a border region of a respective irradiation area IA with respect to a non-consolidated build material area adjacent to or surrounding the irradiation area IA and a second sub-area SA2 may be built by or may comprise an inner region, which may also be deemed or denoted as a non-border region of the respective irradiation area IA with respect to the non-consolidated build material area at least partially adjacent to or surrounding the irradiation area IA. As such, respective border regions which typically coincide with respective first sub-areas SA1 of a respective irradiation area IA may be irradiated before respective non-border regions which typically coincide with respective second sub-areas SA2 of the respective irradiation area IA. This irradiation order also results or contributes in reducing or avoiding undesired accumulation of thermal energy. The width of a respective border region may be a few millimeters. As such, a respective border region may represent a relatively narrow area, particularly a narrow strip-like area, of a respective irradiation area IA.

[0054] As is exemplarily apparent from FIG. 4, 5, an irradiation area IA may comprise a plurality of irradiation area segments IAS1-IAS8 which are separately irradiatable or irradiated with an energy beam 5. The exemplary embodiment of FIG. 4 exemplarily shows an irradiation area IA comprising four irradiation area segments IAS1-IAS4, the exemplary embodiment of FIG. 5 exemplarily shows an irradiation area IA comprising eight irradiation area segments IAS1-IAS8. Of course, other numbers of irradiation area segments IAS are conceivable.

[0055] Thereby, each irradiation area segment IAS1-IAS8 may comprise at least one first sub-area SA1 having a first heat conductance capability and at least one second sub-area SA2 having a second heat conductance capability higher than the first heat conductance capability. In accordance with the method, a respective first sub-area SA1 of a respective irradiation area segment IAS1-IAS8 is irradiated before a respective second sub-area SA2 of the respective irradiation area segment IAS1-IAS8. Likewise, irradiation area segments IAS1-IAS8 having a higher number of first sub-areas SA2 may be irradiated before irradiation area segments IAS1-IAS8 having a lower number of first sub-areas SA1 in an irradiation area.

[0056] As is exemplarily apparent from the view of FIG. 6, a first sub-area SA1 may be located above an (already) non-irradiated and non-consolidated irradiation area of a preceding build material layer 3 and a second sub-area SA2 may be located above an (already) irradiated and consolidated build material area of a preceding build material layer 3. Hence, the differences of the heat conductance capability of first and second sub-areas SA1, SA2 may originate from the contact area of the respective sub-area SA1, SA2 with non-consolidated build material 4 which typically has a low(er) heat conductance capability and conductance and consolidated build material 4 which typically has a high(er) heat conductance capability and conductance. Hence, when a respective sub-area SA1, SA2 comprises a high number of contact areas with non-consolidated build material 4 in a preceding build material layer 3, the heat conductance capability of the respective sub-area SA1, SA2 will be typically lower than when the respective sub-area SA1, SA2 comprises less contact areas with non-consolidated build material 4 in a preceding build material layer 3. As such, a respective first sub-area SA1 may have a larger contact area with non-consolidated build material in a preceding build material layer 3, whereas a respective second sub-area SA2 may have a smaller contact area with non-consolidated build material in the preceding build material layer 3. Conversely, a respective first sub-area SA1 may have a smaller contact area with consolidated build material 4 in a preceding build material layer 3, whereas a respective second sub-area SA2 may have a larger contact area with consolidated build material 4 in the preceding build material layer 4.

[0057] As is further apparent from FIG. 6, respective first sub-area SA1 may be or comprise an overhang region of the object 2 in the respective build material layer 3. A respective overhang region is a region located above at least one non-consolidated build material area of a preceding build material layer 3.

[0058] As is apparent from FIG. 2-6, a respective first sub-area SA1 may at least partially, particularly completely, surround a respective second sub-area SA2 of an IA.

[0059] In either case, at least one pattern parameter, in particular the orientation of at least one irradiation vector IV, of a respective irradiation pattern IP may be changed for irradiating different build material layers 3. As such, at least one pattern parameter of an irradiation pattern used for irradiating a first build material layer 3 which is to be selectively irradiated and consolidated may be changed with respect to at least one pattern parameter of a second irradiation pattern used for irradiating a second build material layer 3. This approach may also result or contribute in reducing or avoiding undesired accumulation of thermal energy.

[0060] Single, a plurality, or all features mentioned in context with a specific embodiment may also apply to other embodiments. Hence, a single, a plurality, or all features mentioned in context with a specific embodiment may be combined with at least one feature of another specific embodiment.