METHOD FOR SELECTIVELY IRRADIATING A POWDER LAYER IN ADDITIVE MANUFACTURING WITH A FIRST AND A SECOND IRRADIATION PATTERN

Abstract

A method for selectively irradiating a powder layer in additive manufacturing of a component. The method including: determining an irradiation pattern of the layer for additive manufacturing, wherein a first partial pattern is defined which is intended for continuous irradiation and comprises a plurality of irradiation vectors and wherein a second partial pattern is defined, which is intended for a pulsed irradiation, with the first and the second partial pattern being selected in such a manner that the second partial pattern connects irradiation vectors of the first partial pattern, and irradiating the layer in accordance with the irradiation patterns defined. A computer program product, an irradiating device, and a control unit for controlling an irradiating device are included.

Claims

1.-9. (canceled)

10. A method for selectively irradiating a powder layer in the additive production of a component, comprising: defining an irradiation pattern of the layer for the additive production, wherein a first partial pattern which is intended for continuous irradiation and comprises a multiplicity of irradiation vectors is defined, and wherein a second partial pattern which is intended for pulsed irradiation is defined, the first and the second partial patterns being selected in such a way that the second partial pattern connects irradiation vectors of the first partial pattern, and irradiating the layer according to the defined irradiation pattern, wherein a beam melting track of regions of the layer which are irradiated with pulses respectively overlaps in a plan view of the layer with beam melting tracks of neighboring regions of the layer which are irradiated continuously, and wherein beam melting tracks of neighboring regions of the layer which are irradiated continuously do not overlap in a plan view of the layer.

11. The method as claimed in claim 10, wherein the irradiation of the layer leads to regions of the layer which are irradiated continuously being connected structurally by regions of the layer which are irradiated with pulses.

12. The method as claimed in claim 10, wherein beam melting tracks of neighboring regions of the layer which are irradiated continuously overlap by less than 60 μm in a plan view of the layer.

13. The method as claimed in claim 10, wherein two neighboring irradiation vectors of the first partial pattern are initially irradiated continuously and a further neighboring irradiation vector of the first partial pattern is subsequently irradiated simultaneously with a region of the second partial pattern, which connects the regions of the irradiation vectors of the first partial pattern.

14. The method as claimed in claim 13, wherein another further neighboring irradiation vector of the first partial pattern is irradiated simultaneously with a further region of the second partial pattern, which connects a region of an irradiation vector of the first partial pattern and a region of the further neighboring irradiation vector of the first partial pattern.

15. A non-transitory computer readable medium, comprising: computer instructions stored thereon which, when run by a computer, cause the computer to define the irradiation pattern as claimed in claim 10.

16. An apparatus, comprising: at least one irradiation device which is adapted to irradiate the layer according to the defined irradiation pattern as claimed in claim 10.

17. A controller which is adapted to drive an irradiation device for selectively irradiating a powder layer according to the irradiation pattern defined in claim 10.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0037] FIG. 1 indicates a powder bed-based additive production method of a component with the aid of a schematic sectional view.

[0038] FIG. 2 indicates an irradiation pattern, which is intended for continuous irradiation operation, with the aid of a schematic plan view of a layer.

[0039] FIG. 3 indicates an irradiation pattern according to the invention, comprising a first partial pattern and a second partial pattern, with the aid of a schematic plan view of the layer.

[0040] FIG. 4 indicates method steps according to the invention with the aid of a schematic flowchart.

DETAILED DESCRIPTION OF INVENTION

[0041] In the exemplary embodiments and figures, elements which are the same or have the same effect may respectively be provided with the same references. The elements represented and their size proportions with respect to one another are not in principle to be regarded as true to scale, and individual elements may instead be represented as being exaggeratedly thick or large for improved representability and/or for improved understanding.

[0042] FIG. 1 shows a schematic sectional view of an additive production installation 100, or a part thereof. The installation is advantageously configured for the additive construction of a component 10 by selective laser sintering, selective laser melting or electron-beam melting.

[0043] Accordingly, the installation comprises a lowerable construction platform 1. A starting material P, advantageously in powder form, is arranged on the construction platform, advantageously by means of a coating device 3. This is done layer-by-layer after each layer L has been selectively exposed according to the desired component geometry by an energy beam, for example a laser or an electron beam. To this end, an irradiation device 2 is provided, which is correspondingly adapted expediently to irradiate the layer L by continuous irradiation operation B1 and by pulsed irradiation operation B2 (indicated by dashes).

[0044] The irradiation device 2 furthermore advantageously comprises a controller for driving the irradiation device 2, which according to the invention is correspondingly adapted to irradiate a layer according to the irradiation pattern presented below. As an alternative, the irradiation device 2 may be interconnected with the controller and/or coupled thereto.

[0045] FIG. 2 shows a simplified schematic plan view of a first irradiation pattern or partial pattern TM1 of or for a layer, in particular a powder layer, such as is successively provided for production of the component 10 (compare FIG. 1). The first partial pattern TM1 is intended for continuous irradiation of the layer, for example by means of a laser in continuous wave operation or quasi-continuous wave operation, or a comparable electron beam. The first partial pattern TM1 furthermore comprises a multiplicity of elongate regions or irradiation vectors V.

[0046] During the subsequent irradiation of a region denoted by the irradiation vectors V, beam melting tracks T1 (or beam welding seams), in which the powder P is locally melted and then solidified, are left behind by the (selective) heat input in this region. In the present case—for the sake of simplicity—a multiplicity of parallel irradiation vectors can be seen. The irradiation vectors V furthermore do not overlap with one another in the plan view shown. By the spacing d denoted, it may be seen that there is no overlap of the corresponding regions here.

[0047] Parallel to a beam melting track T1, FIG. 2 shows (to its right) a second beam melting track T1′ of a second irradiation vector V (not explicitly denoted).

[0048] In an alternative configuration according to the invention, the described irradiation vectors V of the first partial pattern TM1 overlap only very weakly or minimally in a plan view of the layer, for example by less than 75 μm, advantageously less than 60 μm, less than 50 μm, or even less, for instance less than 40 μm or less than 30 μm. By this configuration, the stress state of the freshly solidified regions or the structure of the beam melting tracks is also advantageously kept low.

[0049] In contrast thereto, in conventional irradiation strategies in powder bed-based additive production, corresponding irradiation vectors such as hatch vectors, which are selected for the extensive irradiation of a powder layer, are provided with an overlap in order to generate a structure which is dense and solid but, because of the high temperature gradients involved and the large spatial overlap of the welding tracks obtained, is highly stressed and/or susceptible to cracks.

[0050] For a sufficient structural, geometrically stable and/or materially bonded connection of component material to be irradiated of each layer L, according to the invention a second irradiation pattern or partial pattern TM2 of the layer L is advantageously selected or defined (compare also FIG. 4 below).

[0051] This aforementioned second partial pattern TM2 is schematically indicated in addition to the first partial pattern TM1 in FIG. 3. Overall, a total irradiation pattern is denoted by the reference M.

[0052] In contrast to the first partial pattern TM1, the second partial pattern TM2 is furthermore intended for pulsed irradiation operation, for example by means of a Q-switched or mode-coupled laser.

[0053] The second partial pattern TM2 is selected, configured or arranged according to the invention in such a way that the second partial pattern connects irradiation vectors V or corresponding beam melting tracks of the first partial pattern TM1. This is represented in FIG. 3 by individual, roundly indicated regions for the pulsed irradiation respectively overlapping with two or more neighboring regions of the first partial pattern, in order to allow sufficient structural coherence of the corresponding layer. Overall, for each layer to be (selectively) irradiated of the component—in total there may be thousands or even tens of thousands of layers—a solid and dense material structure is thus obtained.

[0054] The pulsed operation of a laser is distinguished, for example in contrast to a conventional continuous irradiation mode, by a lower temporal or spatial energy input and therefore correspondingly by a reduced thermal load. Advantageously, this automatically in turn significantly reduces the stresses which occur during construction as well as during subsequent processing steps and in operation of the component, and therefore the crack susceptibility of the latter. Although pulsed irradiation operation is significantly more time-consuming or procedurally inefficient than continuous irradiation, the combination of the aforementioned defined or selected irradiation patterns TM1 and TM2 nevertheless allows the low internal stress state of the structure achieved to be obtained by time-efficient production.

[0055] In particular, according to the method according to the invention, described below with the aid of FIG. 4, for additive production, a first and a second melting track of the first partial pattern TM1 are initially irradiated (next to one another). These parallel regions are denoted in FIG. 3 by the numbers 1 and 2 in the lower region. In a next step, a further neighboring irradiation vector T1′ of the first partial pattern TM1 is advantageously irradiated simultaneously with a region T2 of the second partial pattern TM2, the region T2 connecting the irradiated regions T1 of the irradiation vectors of the first partial pattern. This corresponds to simultaneous irradiation of the “pulsed” region a and the “continuous” region 3 in FIG. 3.

[0056] Furthermore, in a next step, another further neighboring irradiation vector T1″ of the first partial pattern is advantageously irradiated simultaneously with a further region T2′ of the second partial pattern TM2, which connects a region T1 of the irradiation vector of the first partial pattern and a region T1′ of the further neighboring irradiation vector of the first partial pattern TM1. This corresponds to simultaneous irradiation of the pulsed regions b and the continuous region 4 in FIG. 3.

[0057] The irradiation of an entire predetermined layer L for the component 10—and furthermore of each further layer for the component—may be carried out accordingly. In particular, as illustrated with the aid of FIG. 3, according to the invention the pulsed region c is then irradiated simultaneously with the region 5 to be irradiated continuously and, inter alia, the pulsed region d is irradiated simultaneously with the region 6 to be irradiated continuously.

[0058] FIG. 4 indicates method steps according to the invention of the proposed method for selectively irradiating a powder layer for additive production of the component 10 with the aid of the schematically shown flowchart.

[0059] Method step (i) denotes the definition of the entire irradiation pattern M of the layer L for the additive production. The irradiation pattern M comprises the above-described first partial pattern TM1 and the above-described second partial pattern TM2. As described above, the partial patterns TM1 and TM2 are advantageously also defined and/or specified according to the invention, for example in the scope of a CAM method.

[0060] The reference CPP is intended to indicate that the definition of the irradiation pattern M may be also carried out according to the invention with computer implementation and/or by a computer program or computer program product. The computer program or computer program product may comprise corresponding instructions or data which, when the program is run, cause a data processing device or a computer to define the irradiation pattern in a corresponding manner according to the invention. Information or data which make it possible to execute the irradiation pattern as proposed according to the invention may accordingly also be present accessibly as stored data.

[0061] Method step (ii) lastly indicates the irradiation of the layer L according to the defined irradiation pattern, so that the component can actually be constructed layer-by-layer.

[0062] Optional method step (iii) is intended to indicate that, for the final production of the component 10, a multiplicity of further layers need to be selectively irradiated and solidified, and that optional finishing steps of mechanical or thermal nature may possibly be necessary or helpful.

[0063] The component 10 which may be provided with the aid of the irradiation pattern M proposed according to the invention, comprising the first partial pattern TM1 and the second partial pattern TM2, with significantly improved structural properties, i.e. particularly a lower stress state, is advantageously a component which is used in the hot-gas path of a turbomachine, for example a gas turbine. In particular, the component may refer to a rotor blade or guide vane, a ring segment, a burner part or a burner tip, a shroud, a screen, a heat shield, a nozzle, a seal, a filter, an orifice or lance, a resonator, a piston or a swirler, or a corresponding transition, insert, or a corresponding retrofit part.

[0064] By the description with the aid of the exemplary embodiments, the invention is not restricted thereto but comprises any new feature and any combination of features. In particular, this includes any combination of features in the patent claims, even if this feature or this combination itself is not explicitly specified in the patent claims or the exemplary embodiments.