WO2023041597A1

WO2023041597A1 - Adaptive scan area assignment for additive manufacturing

Info

Publication number: WO2023041597A1
Application number: PCT/EP2022/075552
Authority: WO
Inventors: Timo Schudeleit; Thelacsan SIVAKUMAR; Egon Seegers
Original assignee: Turbo Systems Switzerland Ltd.
Priority date: 2021-09-14
Filing date: 2022-09-14
Publication date: 2023-03-23

Abstract

A method for additive manufacturing of a. build-job, by means of a plurality of focused energy beams is described. The method includes accessing a digital build- job model for the build-job to be formed; and determining, for each of the focused energy beams (102, 103, 104, 105), of a respective section (130, 140, 150, 1.60) within a working area. (120) of the powder 'bed (1 10). The method, further includes providing a top powder layer (11. 1) of the powder bed. (110); and forming a build- job layer (210) by selectively consolidating powder of the top powder layer ( 1 1 1) by the focused, energy beams (102, 103, 104, 105), whereby each of the focused energy beams ( 102, 103, 104, 105 ) operates within its respective section ( 130. 140, 150, 160). Furthermore, a manufacturing apparatus for additive manufacturing of a build-job and a computer program comprising instructions arc described, herein.

Description

ADAPTIVE SCAN AREA ASSIGNMENT FOR ADDITIVE MANUFACTURING

TECHNICAL FIELD

| Embodiments of the present disclosure relate to a method for additive manufacturing of a build-job, specifically a powder-bed additive manufacturing method using focused energy beams. Further embodiments relate to a manufacturing apparatus for additive manufacturing of a build-job and a computer program comprising instructions therefor.

BACKGROUND

[0002] Powder-bed additive manufacturing methods commonly make use of several energy sources, such as a laser source, for providing focused energy beams consolidating a powder provided in the powder bed. These energy sources can operate simultaneously in order to speed up the manufacturing process. When additive manufacturing is carried out with multiple lasers, these lasers can be assigned to areas within a build-job in order to melt the material in parallel.

[0003] During the consolidation process, each focused energy beam creates sputter and condensate (which may also be referred to collectively as debris), which may be flushed out of the machine room by an inert gas flow, in order to keep the build chamber clean and not affect any components, such as optics or the laser beam. If a single energy source works on a part, there is no interference with debris from other beams. The interference with the beam’s own debris is negligible. As soon as multiple energy sources work in parallel, such interference can occur, namely if one focused energy beam scans through the debris generated by another focused energy beam. Condensate or sputter generated by an energy source can adversely affect the quality of consolidation of the powder to be fused.. The effective energy intensity applied to the powder is lower due to the debris interfering with the focused energy beam and the material properties worsen, since the necessary melt power is not reached.

[0004] A high productivity manufacturing process may be reached by using all energy sources in parallel with no interruption. A high-quality build-qob is reached by selectively deactivating some of the energy sources at certain points in time to avoid scanning too close or in the condensate of another energy source. The high-productivity approach oftentimes leads to inferior quality build-jobs due to abo\ ementioned interference. The high-quality approaches known in the art are inefficient.

[0005] Two approaches are known in the art:

1) Fixed scan areas are assi gned for each of the energy sources by splitting the working area or build plate in fixed scan regions (i.e. equal scan regions for each focused energy beam) for each focused energy sources or, with small overlap between the scan areas. This method largely avoids scanning in the condensate of another energy source, and therefore can result in a high material quality, but typically leads to a decrease in productivity. In certain build-jobs, the method may for example allow for a laser utilization during consolidation of below 70%, for certain types of build-jobs the laser utilization can be far below 70%.

2) The assignment is carried out by a laser assignment tool that finds a compromise between productivity and quality. This method makes use of optimizers to delay (temporarily switch off) the energy beams that would be disturbed, and enables to increase the productivity by accepting compromises in the material quality (i.e. by allowing the focused energy beam to scan through the debris generated by another focused energy beam at times). This method can enable a laser utilization of above 80% for certain build-jobs. However, this method results in lower material properties (such as high porosity, or low tensile strength), which for many applications is insufficient.

100061 There is a continuous demand for improved additive manufacturing methods. In particular, there is a need for additix c manufacturing methods which allow for a high laser utilization while, while not compromising the material quality of the build-job.

SUMMARY

[0007] In light of the above, a method for additive mwufocturing of a buildjob according ti> independent claim 1, a manufacturing apparatus for additive manufacturing of a build- job according to claim 15 and a computer program according to claim 16 arc provided. Further aspects, advantages, and features are apparent from the dependent claims, the description, and the accompanying drawings.

[0008] According to an aspect of the present disclosure, a method for additive manufacturing, by means of a plurality of focused energy beams, of a build-job including one or more workpieces in a layered manner from a powder provided in a powder bed is provided. The method includes accessing a digital buildqob model for the buildqob to be formed. Further, the method includes determining, for each of the focused energy beams, of a respective section within a working area of the powder bed. Each of the sections is detennined based on a respective partial build-job amount calculated from a respective build-job portion of the digital build-job model, in particular within the respective section. The method includes pro\ iding a top powder layer ofthe powder bed; and forming a build-job layer by selectively consolidating powder of the top powder layer by the focused energy beams, ’whereby each of the focused energy beams operates within its respective section.

[0009] “Build-job” is to be understood as the entirety of components to be manufactured in one particular manuficturing process. The build-job can contain only one workpiece to be manufactured, such as a turbomachinery component, and therefore the build-job can be the workpiece. In alternative embodiments, several workpieces may be formed in one particular manufacturing process, especially in case the w orkpiece to be formed is substantially smaller in comparison to the powder layer. In this case, the build-job contains two or more workpieces.

[0010] The focused energy beams are not particularly limited to a specifictype of energy beam. The focused energy beam may be selected from the group consisting of a laser beam, an electron beam, an electric arc and a plasma arc. Preferably, the focused energy beam is a laser beam. The method utilises several focused energy beams. Typically, at least three, and preferably four or more focused energy beams are used.

[0011 ] The powder may be provided as a powder bed in a layered manner as known in the art. The powder may include a polymeric powder, a ceramic powder and/or a metallic powder, preferably be a metallic powder.

[0012] The method includes accessing a digital build-job model for the build-job to be formed. The digital build-job model may be a CAD (computer-aided design) drawing or any other form of digital model containing the design of the build-job to be formed, i.e. the design of all workpieces contained in the build-job. The digital build-job model may also contain other information such as information regarding materials, processes, tolerances, and other data.

[0013] The working area is a space within the powder bed in which the build-job is formed. In some embodiments, the powder bed and the working area may have the same dimensions, for example in ease the entire powder bed is used for forming the build-job. Typically. the working area may be defined such that it is smaller than the powder bed. Although the working area may ha\ c any shape, including irregular forms, it is preferred that the working area is of a symmetric shape such as a cuboid, in some ease cubic, ora circular shape. The working area may have a smallest predefined shape, such as a cuboid shape, which fully contains the build-job to be formed. However, defining the working area substantially larger than the build-job or even equal to the powder bed is not detrimental to the productivity as the respective sections in which each of the focused energy beams operates is derived from the geometrical properties of the build-job (i.e. deriv ed from the digital buildjob model).

[0014] The working area is subdivided or split into several sections. The number of sections preferably corresponds to the number of focused energy beams.

100151 According to a preferred embodiment, the sections are nonintersecting and each abut against al least one adjacent section. Although the sections arc non-intersecting or non-overlapping, and each of the focused energy beams operates within its respective section, it is to be understood that the focused energy beams hav e a finite cross-section (such as a few hundred microns), and that a portion of the cross-section may irradiate a neighbouring section even when operating within its respective section. Thus, the focused energy beams may operate at the border of two adjacent sections, and may partially irradiate the neighbouring section, thereby resulting in a small ov erlap between the area irradiated by the focused energy beams. Operating the focused energy beams at the border of two adjacent sections helps to ensure high quality material properties throughout the entire build-job, which otherwise may be impaired at the border between two adjacent sections. [0016] Each of the sections preferably abuts against at least one adjacent section along a major axis of the section. The major axis is defined as extending parallel to a direction of inert gas flow for removing debris. An extent of the working area or section along the major axis may also be referred to as length or depth of the working area or of the sections.

| ()() 171 The sections may not abut against other sections along a minor axis of the section. The minor axis is defined as extending perpendicular to the major axis, and perpendicular to the direction of inert gas flow for removing debris. An extent of the working area or section along the minor axis may also be referred to as width of the working area or width of the sections.

[0018] Although the sections may have any shape, including irregular forms, it is preferred that the sections area are defined as being parallel to one of the build-job layers, and preferably parallel to all of the build-job layers. It is further preferred that each of the sections corresponds to one continuous and connected (uninterrupted) area or volume, i.e. not comprising several disjoint areas or volumes.

[0019] In an embodiment, each of the sections defines a substantially rectangular shape with the major axis extending parallel to the direction of inert gas flow. As described further below, the sections may extend over just one buildyjob layer, or may extend over several or even all build^job layers. In some embodiments, the sections may have a cuboid shape.

[0020] In a preferred embodiment, each section extends, in a length direction, over the entire length of the working area. In other words, the depth of the section may correspond to the depth of the working area. In this embodiment, the sections may also be referred to as lanes. Advantageously, defining the sections as extending over the entire length of the working area reduces the possibility for one focused energy beam scanning through the debris generated by another focused energy beam, which may scan further upstream along the direction of inert gas flow. 101)21 1 The method for additive manufacturing of a build-job further includes determining, for each of the focused energy beams, of a respective section within a working area of the powder bed. The respectiv e sections arc deriv ed from a respectiv e partial build-job amount, w hich is deriv ed from a respective build-job portion, w hich in turn is derived from the digital buildjob model. In other words, a respective section is determined indiv idual ly for each focused energj beam, based on a rcspectixc partial build-job amount, which is also determined indix idually for each focused energy beam (or section). The rcspectix c partial build-job amount is determined from the respective build-job portion, which is also determined indix idually for each focused energy beams (or section ) from the digital build-job model.

|O()22 ] For the purpose of determining respective sections only a certain part (build-job portion) of the digital build-job model may be used. For example, the build-job portion may be limited to a specific layer (such as one build-job layer) ofthc digital build-job model. In another illustrative example, the build-job portion max' be limited to the digital build-job model within the respectiv e section. As opposed to the build-job portions, the sections may contain powder to be fused (corresponding to the build-job portion) as well as pow der which is not fused during the manufacturing process.

|OO23 ] Each of the sections is determined based on a respective partial build-job amount. The partial build-job amount is a scalar quantity calculated from the respectiv e build-job portion, which typically corresponds to an area or a v olume within the digital build-job model.

[0024] The partial build-job amount allows for quantifying a certain physical property of the build-job portion. The (respectiv e) partial build-job amount is preferably calculated as a partial mass to be consolidated (e.g. fused, melted, or sintered) or a partial area to be consolidated or a partial v olume to be consolidated of thc build-job portion, in particular within the respective section. [0025] The method of the present disclosure includes predetermining sections for the focused energy beams to operate in. which arc calculated based on portions of the digital build-job model, or in other words portions of the (top) powder layer or the woAing area in which powder is actually consolidated or fused as opposed to dividing the powder layer or the working area in (equally sized) areas. The sections are not fixed or predetermined by the powder layer or the working area, but are adaptive, i.e. are adapted to the geometry of the build-job.

100261 Embodiments of the present disclosure allow for the focused energy beams to operate with high energy beam utilization. The sections or scan areas are adapted in order to reach a similar workload for each of the focused energy beams. Typically, the method described herein allows for energy beam utilization rates in excess of 90%, and in preferred embodiments energy beam utilization rates in excess of 95% are achieved. Hence, compared to the prior art, a productivity gain of more than 20% pts can be reached.

[0027] The methods of the present disclosure therefore avoid idle times of the focused energy beams. The method described herein also enables high- quality build-jobs as the focused energy beams operate within their respective sections, and scanning of one focused energy beam through the debris generated by another focused energy beam is reduced to a minimum or even completely avoided. Typically, none of the focused energy beams are switched off (apart from brief idle times when readjusting the alignment of the focused energy beams) until all the powder to be fused is consolidated within the respective section. In other words, the method includes forming the build-job layer by selectively consolidating powder of the top powder layer by continuously operating at least one, preferably all, of the plurality of focused energy beams. Briefly summarised, the present disclosure sets forth an adaptiv e (build-job geometry depending) consolidation approach that enables all focused energy beam to work in parallel (enabling high productivity), while not compromising the material quality. [0028] For specific build-]obs, the respective sections, the partial build-job amounts, and the build-job portions may be calculated analytically. For example, an exemplary method may include utilising two focused energy beams, dividing the working area into two rectangular shaped sections, and manufacturing a build-job containing one single workpiece. In this case the respective build-job portion may be derived from one workpiece layer. A center of mass of the digital buildiob model may be determined and the respective build-job portions may be determined as the major axis passing through the centre of mass.

[0029] For other build^jobs, the respective sections, the partial build-job amounts, and the build-job portions may be calculated in an iterative manner. After selecting the number of focused energy beams, and optionally selecting a geometrical shape of the respective sections, the respective sections, the partial build-job amounts, and the build-job portions may be determined by an optimization algorithm.

10030] According to an embodiment, the respectiv e sections arc determined by an optimisation algorithm aiming for or targeted at obtaining substantially equal partial build-job amounts in the sections. In other words, the method includes determining each of the respective sections such that each of the sections contains substantially equal partial build-job amounts, e.g. the same partial mass to be consolidated or the same partial area to be consolidated or the same partial volume to be consolidated. The individual sections therefore typically do not have the same area or the same volume, but instead include the same mass or area or volume to be consolidated. This allows for all focused energy beams to have approximately the same workload and preferably to complete their respective consolidation jobs at approximately the same point in time, thus resulting in high utilization of the focused energy beams, and thus a high productivity, while minimising laser interference, and therefore enabling high surface quality and material characteristics. [0031] The optimisation algorithm may aim at achieving substantially equal partial build-job amounts by iteratively optimising the respective build-job portions, and thereby iteratively optimizing the respective sections.

[0032] According to an embodiment, the builebjob portion of the digital build^job is determined as the intersection or overlap of at least a layer of the digital build-job model with the respective section, illustratively, the buildjob portion of the digital build-job may be determined as the intersection of one specific layer of the digital build-job model - such as the specific layer ofthe digital build-job model corresponding to the build-job layer to be formed - with the respective section. The respective build-job portion may then correspond to an area (or alternatively a volume with the height being one powder layer or one build-job layer). Illustratively, the build-job portion of the digital build-job may be determined as the intersection of the digital buildjob model, i.e. of all layers of the digital build-job model, with the respective section. The respective build-job portion may then correspond to a volume. The build-job portion, the build-job amount and the respective sections may preferably be optimised iteratively.

[0033] The method farther includes providing a top powder layer of the powder bed and forming a build-job layer by selectively consolidating powder of the top powder layer by the focused energy beams. Each of the focused energy beams operates within its respective section.

[0034] According to an embodiment, a plurality of build-job layers are formed on top of each other by repeating the steps of providing a top powder layer of the powder bed, and of forming a build-job layer by selectively consolidating powder of the top powder layer by the focused energy beams.

Two preferred embodiments of determining the respective sections are described below for the case of forming a plurality of build-job layers.

[0035] The respective sections for the focused energy beams may be determined for each of the build-job layers indiv idually. In this case, a plurality of sections, and a plurality of build-job portions of the digital buildjob model are determined for each build-job layer. The build-job portion of the digital build-job model is determined as the intersection of the respectiv e one of the buildjob layers of the digital build-job model with the respective section. In other words, the method includes determining dimensions of the respective sections individually for each build-job layer, in particular by the optimization algorithm for obtaining equal partial build-job amounts in the sections for each of the layers. The respective build-job portion may then correspond to an area (or alternatively to a volume with the height being one powder layer or one build-job layer). The build-job portions may be determined such that for each respective build-job layer each of the sections contains substantially the same mass of powder to be consolidated and/or substantially the same area to be consolidated. This embodiment results in a high laser utilization in excess of 90%, and for certain build-jobs in excess of 05%. and is particularly advantageous when the geometry of the build-job varies significantly in the build direction, for example in case a workpiece tapers or flares out in the build direction.

[0036] Alternatively, the respective sections for the focused energy beams may be determined initially, wherein the build-job portion is determined as the intersection of the plurality of the build-job layers of the digital build-job model with the respective section for the plurality of layers. In this embodiment, the build-job portion is preferably determined from all the layers of the digital build-job model. The respective build-job portion may then correspond to a volume (with the height of the section corresponding to the height of the build-job). In this case, a plurality of sections, and a plurality of build-job portions of the digital build-job model arc determined once for the plurality of build-job layers. In other words, the method includes determining dimensions of the respectiv e sections once for the plurality of build-job layers, in particular by the optimization algorithm for obtaining equal partial build-job amounts in the sections for the plurality of build-job layers. This embodiment is simple to implement, and results m a high laser utilization in excess of 90%, in particular when the geometry of the build-job does not vary strongly in the build direction.

[0037] According to an embodiment determining of the rcspectix e sections includes the determining of the width of the sections, i.e. the extent of the section along the minor axis. The sections may be predefined as extending over the entire length of the working area. As described above, the sections may be determined for each of the build-job layers individually, or respective sections may be determined initial ly. In both cases, the height of the sections may also be predefined. In this case, determining of the respective sections corresponds to determining of the width of the sections, i.c. only the width of the sections is optimised by the method.

[0038] In another embodiment, the method includes further subdividing the sections into sub-sections. Dividing the sections into sub-sections advantageously allows for largely synchronising the consolidation step carried out by the focused energy beams, by ensuring that each of the focused energy beams operate at a similar depth (along the major axis) of the working area. When the focused energy beams consolidate the powder at a similar depth, it can be largely av oided that one focused energy beam scans through the debris generated by another focused energy beam. Debris generated during consolidation by the focused energy beam may have point-like dimensions when generated but can result in a conical-like shape with an increasing width along the direction of inert gas flow. Therefore, debris generated in a first section can interfere with the focused energy beam in an adjacent, non-overlapping second section in case the focused energy beam inthe second section is sufficiently far downstream from the focused energy beam in the first section.

[0039] The method may include subdividing the sections into sub-sections along the direction of inert gas flow. In other words, each of the sub-sections of a respective section abuts against an adjacent sub-section of that section m the direction of inert gas flow, and is non-intersecting or non-overlapping with the adjacent sub-section.

[0040] Although the sub-sections are preferably non-intersecting or nonoverlapping, the focused energy beams may operate at the border of two adjacent sub-sections, and may partially irradiate the neighbouring subsection, thereby resulting in a small overlap between the area irradiated by the focused energy beams while it is scanning one sub-section and later on while it is scanning the adjacent sub-section. Scanning at the border between sub-sections helps to ensure high quality material properties throughout the entire build-job, which otherwise may be impaired at the border between two sub-adjacent sections.

[0041 ] The sub-section may have a rectangular or cuboid shape. A width of the sub-section, i.e. the extent of the section along the minor axis, and the width of the respective section may be substantially the same.

[0042] Preferably each of the focused energy beams operates within adjacent, preferably abutting, sub-sections. In other words, a first focused energy beam operates within a sub-section in a first section which is adjacent to, and preferably abutting, a sub-section of the second section in which a second focused energy beam operates. Therefore, each of the focused energy beams preferably operate within adjacent sub-sections at a similar depth, i.e. sub-sections which arc as close as possible to each other along the major axis.

10(1431 The method may include successively consolidating powder in each of the sub-sections along one substantially continuous direction along the major axis. The method preferably includes successively consolidating powder in each of the sub-sections in an order from downstream to upstream with respect to the direction of inert gas flow. The method may include successively consolidating powder commencing with the sub-section furthest downstream of the direction of inert gas flow . [0044] In an embodiment, the method includes determining each subsection, in particular a depth (or length along the direction of inert gas flow or the major axis) of each sub-scction. by an optimization algorithm aiming for or targeted at obtaining equal partial build-job amounts in the subsections. In other words, the method includes determining each of the subsections such that each of the sub-sections contains substantially the same partial mass to be consolidated or the same partial area to be consolidated or the same partial volume to be consolidated. The individual sub-scctions typically do not have the same area or the same volume, but instead include the same mass or area or volume to be consolidated. This approach allows for operating the focused energy beams at similar depths in a controllable maimer, and therefore allows for avoiding one focused energy beam scanning through the debris generated by another focused energy beam.

[0045] The method may further include, subsequently to the step of forming the build-job layer, the step of consolidating the contours of the build-job layers.

[0046] In one illustrative embodiment, the step of consolidating the contours of the build- job layer is carried out with only one of the plurality of focused energy beams. This approach does not require an optimisation step as only one focused energy beam is used to optimise the contours of the buildjob layer. Due to the contour optimisation step requiring much less time than forming of the build-job layer, this approach with only one focused energy beam only slightly decreases the productivity.

[0047] In another illustrative embodiment, the step of consolidating the contours of the build-job layer is carried by means of utilising each of the plurality of focused energy beams in the respective section. The method preferably includes successively consolidating the contours of the build-job layer in an order from downstream to upstream with respect to the direction of inert gas flow. [0048] The method preferably further includes continuously flushing a chamber of a manufecturiiig apparatus with inert gas while forming each of the plurality of build-job layers.

[0049] The method for additrie manufacturing described is suitable for manufacturing any type of workpiece. In preferred embodiments, the workpiece is a turbomachinery component, in particular a turbine component or a compressor component, such as a nozzle ring or a bladed turbine wheel or a bladed compressor wheel. The methods described herein arc particularly advantageous in case the build-job contains several workpieces and/or in case the workpiece has a reduced or lower symmetry, such as when the workpiece is non-rotationallv symmetric. In such cases, the method allows for energy beam utilisations in excess of 90%, whereas prior art methods have very limited productivity rates, since the area each laser or focused energy beam has to solidify can vary largely depending on the workpiece geometry.

[0050] According to another aspect of the present disclosure, a manufacturing apparatus for additive manufacturing of a build-job including one or more workpieces in a layered manner from a powder provided in a powder bed is provided. The apparatus includes a powder bed, a powder layering device for prov iding a top powder layer in the powder bed: and a plurality of focused energy beam devices for producing respective focused energy beams capable of selectively consolidating the powder of the top powder layer. The apparatus further includes a controller for directing the focused energy beam devices. The controller includes program code configured to instruct the controter to carry out the method according to any embodiment disclosed herein.

[0051] The manufacturing apparatus includes a chamber or build chamber containing the powder bed, the powder layering dcx icc and optionally the plurality of focused energy beam devices therein . [0052] The manufocturing apparatus may further include an inert gas flow apparatus for removing debris from the chamber. The inert gas flow apparatus is configured for flushing the chamber with inert gas while forming each of the plurality of build-job layers. The inert gas flow apparatus may be configured for injecting inert gas proximate to a first end of the chamber and sucking out or syphoning out the inert gas at an opposite second end of the chamber.

[0053] The controller may be further configured to operate other components of the manufacturing apparatus, such as the powder layering device or inert gas flow apparatus.

[0054] According to another aspect of the present disclosure, a computer program including instructions 'which, when the program is executed by a computer, cause the computer to carry out the following steps of the method according to any embodiment disclosed herein: accessing a digital build-job model for a build-job to be formed; and determining of a respective section for each of a plurality of focused energy beams, within a working area. Each of the sections is determined based on a respective partial build-job amount calculated from a respective build-job portion of the digital build-job model within the respective section.

[0055] The computer program including instructions which, when the program is executed by a computer, may cause the computer to carry out one or more of the following steps: a) Calculate the respective partial build-job amount for each section as a partial mass to be consolidated or a partial area to be consolidated or a partial volume to be consolidated of the build-job portion; and/or b) Determining the respective sections by an optimization algorithm for obtaining substantially equal partial build-job amounts in the sections; and/or c) Determining the build-job portion of the digital build-job as the intersection of at least a layer of the digital build-job model with the respective section, preferably as the intersection of the digital buildjob model with the respective section; and/or d) Determining the respective sections for the focused energy beams for each of the build- job layers individually, wherein the build-job portion of the digital build job model is determined as the intersection of the respective one of the build-job layers of the digital build-job model with the respective section; or e) Determining the respective sections for the focused energy beams initially. wherein the build-job portion is determined as the intersection of the plurality of the build- job layers of the digital build-job model with the respective section for the plurality of layers.

[0056] Further, the computer program including instructions which, when the program is executed by a computer, may cause the computer to carry out one or more of the following steps: a) Determining each of the sections such that the sections are nonintersecting and each abut against at least one adjacent section; preferably along a major axis of the section, the major axis extending parallel to a direction of inert gas flow for removing debris; and/or b) Determining each section such that the sections extend, in a length direction, over the entire length of the working area (120); and/or c) Determining of the sections including the determining of the width of the sections; and/or d) Subdividing the sections into sub-sections, whereby each of the focused energy beams operate within adjacent, preferably abutting, sub-sections; and/or e) Determining a length of each sub-section along the direction of inert gas flow by an optimization algorithm for obtaining equal partial build-job amounts in the sub-sections.

[0057] Those skilled in the art will recognise additional features and advantages upon reading the following detailed description, and upon viewing the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0058] The components in the Figures are not necessarily to scale, instead emphasis being placed upon illustrating the principles of the invention. Moreover, in the Figures, like reference signs designate corresponding parts. The accompanying drawings relate to embodiments of the disclosure and are described in the following:

Fig. 1 illustrates parts of a method for additive manufacturing of a buildjob comprising one workpiece according to embodiments described herein;

Fig. 2a illustrates parts of a method for additive manufacturing of a buildjob comprising one workpiece according to embodiments described herein;

Fig. 2b illustrates parts of a method for additive manufacturing of a buildjob comprising one workpiece according to embodiments described herein.

Fig. 3 illustrates parts of a method for additive manufteturing of a buildjob comprising three workpieces according to embodiments described herein;

Fig. 4 illustrates parts of a method for additive manufacturing of a build- job comprising one workpiece according to embodiments described herein;

DETAILED DESCRIPTION OF EMBODIMENTS

[0059] Reference will now be made in detail to the various embodiments,

5 one or more examples of which are illustrated in each figure. Each example is provided by way of explanation and is not meant as a limitation. For example, features illustrated or described as part of one embodiment can be used on or in conjunction with any other embodiment to yield yet a further embodiment. It is intended that the present disclosure includes such modifications and variations.

[0060] Within the following description of the drawings, the same reference numbers refer to the same or to similar components. Generally, only the differences with respect to the individual embodiments are described. Unless specified otherwise, the description of a part or aspect in one embodiment can,5 apply to a corresponding part or aspect in another embodiment as well.

[0061] With exemplary reference to Fig. 1, parts of nianufacturing apparatus for additive manufacturing of a build^job 200 and parts of a method for additive manufecturing of a build^ob 200 are described. Figure 1 shows a top view. The arrow 101 on the right-hand side indicates the direction of inert gas flow for removing debris.

[0062] The apparatus includes a powder bed 110, including a top powder layer 111. Figure 1 shows a top view of the powder bed 110. The apparatus further includes a powder layering device for providing the powder layers in the powder bed 110, and a plurality of focused energy beam devices, both of5 which are not shown in Figure 1. The focused energy beams 102, 103, 104, 105 produced by the plurality of focused energy beam devices are sketched as dashed lines. The focused energy beams 102, 103, 104, 105 are laser beams. The plurality of energy beam devices can be laser apparatuses. For example, each laser beam device can be provided as a separate laser apparatus. Alternatively, a plurality of laser beam devices can be prodded by fewer, or a single, laser beam device(s) whose beam(s) are subsequently split by beam splittefes). Alternatively, a laser beam device can be obtained by a plurality of laser beam devices whose beams are subsequently merged into a higher-energy beam.

100631 The build-job 200 includes one single workpiece 210. The working area 120 is an area within the powder bed in which the build-job 200 is formed. Figure 1 shows a top view of the working area 120, which has a cuboid shape (or quadratic shape when x iewed from the top).

[0064] The working area 120 is sub-divided into four respective sections 130, 14(1, 150. 160, one for each focused energy beam 102, 103, 104, 105. The four sections 130, 140, 150, 160 each are of cuboid shape (or of rectangular shape when viewed from the top). Each of the sections extend along the entire depth (i.c. the length along the major axis defined as extending parallel to the direction of inert gas flow 101 ) of the working area 120. Moreover, each of the sections 130, 140, 150, 160 extend along the entire height (i.e. the length along the build direction 106 as indicated in Figures 4a and 4b) of the working area 120.

[0065] In this example, the step of determining of the sections corresponds to determining of the widfo W of the respective sections 130, 140, 150, 160.

[0066] The four sections are determined based on a respective partial buildjob amount. In this example, the respective partial build-job amounts are calculated as a partial mass to be consolidated (based on a centroid of the digital build-job model).

[0067] The respective sections 130, 140, 150, 160 for the focused energy beams 102, 103, 104, 105 are further determined initially. The build-job portion is determined as the intersection of the plurality of the build-job layers of the digital build-job model, i.c. the entirety of the build-job layers, with the respective section 130, 141). 150, 160 for the plurality of layers. This step results in four sections with differing widths. The two inner sections 140, 150 have a greater width compared to the outer sections 130, 160. The laser beams continuously consolidate powder when scanning along (or against) the direct of inert gas flow in the outer sections 130, 160. In the inner sections 140, 150 the workpiece 210 has a gap in the central area in which there is no powder to be consolidated. For that reason, the determined sections based on the respective partial build^job amount result in greater widths for the inner sections 140, 150 compared to the outer sections 130, 160, such that the lasers have more powder to consolidate in the upper and lower portions of the sections to compensate for the gap in the centre. An approach based on splitting the workpiece into four equal area sections would result in substantial idle times for the inner laser beams 103, 104 and reduce the productivity.

|006K | Figure 2a shows another illustrative embodiment of a side v iew of parts of a manufictaring apparatus for additive manufacturing of a build-job 200 and of parts of a method for additive manufacturing of a build-job 200 comprising one workpiece 210.

[0069] Although the workpiece 2 10 is different in comparison to Figure 1 , the manufacturing apparatus is the same as in Figure 1 and the method is carried out in a corresponding manner.

[0070] In particular, the working area 120 is sub-div ided into four respective sections 130, 140, 150, 160, one for each focused energy beam 102, 103, 104, 105. The four sections 130, 140, 150, 160 each are of cuboid shape (or of rectangular shape when viewed from the side). Each of the secti ons extend along the entire depth (not shown in Figure 2a) of the working area 120. Moreover, each of the sections 130, 140, 150, 160 extend along the entire height of the working area 120.

[0071] In this embodiment, the step of determining of the sections coresponds to determining of the width W of the respective sections 130, 140, 150, 160.

100721 The respectiv e sections 130. 140. 150, 160 for the focused energy beams 102. 103, 104, 105 arc further determined initially. Therefore, the build-job portion is determined as the intersection of the plurality of the buildjob layers of the digital build-job model, i.c. the entirety of the build-job layers, with the respective section 130. 140. 150, 160 for the plurality of layers. This step results in four sections w ith differing widths. The areas marked as LI , L2, L3 and L4 each correspond to one of the sections 130, 140, 150, 160.

[0073 ] Figure 2b shows another illustrativ e embodiment of a side v iew of parts of a manufacturing apparatus and of parts of an alternative method for additive manufacturing of a build-job 200 comprising one workpiece 210.

|OO74| The respectiv e sections for the focused energy beams 102, 103, 104, 105 arc determined for each of the build-job layers indiv idually The buildjob portion of the digital build-job model is determined as the intersection of the respectiv e one of the build-job layers of the digital build-job model w ith the respective section. In other words, the respectiv e sections correspond to areas (the sections may also be v iewed as of cuboid shape with the height corresponding to one powder layer). 1 hcrefore. for every build-job layer 210 that is formed, a new set of four sections is determined The areas labelled as LI . L2, L3 and L4 do not correspond to sections, but rather show the combination of all first, second, third and fourth sections, respectiv ely. As becomes apparent from Figure 2b, this approach differs in that the w idth of the sections can v ary along the build direction 106 (along the height). [ 0075 ] The illustrative embodiment of Figure 2b is particularly adv antageous. when the geometry of the build-job substantially changes in the build-direction. This approach ensures that for every build-job layer 210 that is formed each laser has a comparable workload. For example, in case the workpiece has the shape of a pyramid, this embodiment is particularly advantageous, and leads to an additional productivity increase compared to an embodiment in which the respectiv e sections of the focused energy beams are determined initially and then kept constant for all layers.

[ 0076] Figure 3 shows another illustrative embodiment of a top view of parts of a manufacturing apparatus for additive manufacturing of a build-job 20(1 and of a method for additive manufacturing of a build-job 200. The method is carried out in a maimer corresponding to that already described with reference to Figure I, with the difference that the build-job 200 includes three workpieces 201, 202, 203 ,

[0077] The respective sections 130, 140, 150, 160 for the focused energy beams 102, 103, 104, 105 are determined initially. Therefore, the build-job portion is determined as the intersection of the plurality of the build-job layers of the digital build-job model, i.c. the entirety of the build-job layers, with the respcctiv e section 130. 140. 150, 160 for the plurality of layers.

[ 0078 ] This step results in four sections with differing widths. The two inner sections 140, 150 have a substantially smaller width compared to the outer sections 130, 160.

[0079] Figure 4 shows another illustrativ e embodiment of a top view of parts of a manufacturing apparatus for additive manufacturing of a build-job 200 and of parts of a method for additive manufacturing of a build-job 200.

[0080] The build-job 200 illustrated in Figure 4 is identical to the build-job shown in Figure 1. The method is carried out in accordance with the method described with reference to Figure 1, apart from the differences pointed out below,

[0081] The working area 120 is sub-divided into four respective sections 130, 140, 150, 160, one for each focused energy beam 102, 103, 104, 105. The four sections 130, 140, 150, 160 each are of cuboid shape (or of rectangular shape when viewed from the top). Each of foe sections extends along the entire depth of the working area 120. and along the entire height of the working area 120. The step of determining of the sections corresponds to determining of the width W of foe respective sections 130, 140, 150, 160.

[0082] The four sections are determined based on a respective partial buildjob amount. In this example, the respective partial build-job amounts are calculated as a partial mass to be consolidated,

[0083] The respective sections 130, 140, 150, 160 for the focused energy beams 102. 103, 104, 105 arc further determined initially. Therefore, the build-job portion is determined as the intersection of the plurality of the buildjob layers of foe digital build-job model, i.e. the entirety of the build^job layers, with foe respective section 130, 140, 150, 160 for the plurality of layers. This step results in four sections with differing widths.

[0084] Moreover, the method illustrated in Figure 4 includes further subdividing the sections 130, 140. 150, 160 into sub-sections 131. 132, 141 , 142, 151, 152, 161, 162. The sub-sections 131, 132, 141, 142, 151, 152, 161, 162 have a cuboid shape (or a rectangular shape when viewed from the top). A width of each of the sub-sections 131, 132, 141, 142, 151, 152, 161, 162 is the same as the width of the respcctix e section 130. 140, 150, 160.

[0085] The method further preferably includes determining a length L of each sub-section 131, 132, 141, 142, 151, 152, 161, 162 along the direction of inert gas flow 101 by an optimization algorithm for obtaining equal partial build-job amounts in the sub-sections 13 1. 132, 141. 142. 151. 152. 161 , 162. Although the sub-sections arc shown in Figure 4 as all having comparable lengths, each sub-section of each respective section may have a different length L.

100X61 Each of the lasers beams 102. 103. 104. 105 operates w ithin adjacent, preferably abutting, sub-sections 132, 142. 152, 162. In Figure 4. the laser beams preferably first consolidate the powder m each of the dow nstream sub-sections 132. 142, 152. 162. and subsequently consolidate the powder in each of the upstream sub-sections 131 , 141. 151. 161.

100X71 While the foregoing is directed to embodiments, other and further embodiments may be devised without departing from the basic scope, and the scope is determined by the claims that follow.

REFERENCE NUMERALS

101 direction of inert gas flow

102, 103, 104, 105 focused energy beams

106 build direction 110 powder bed

111 top powder layer

120 working area

130, 140, 150, 160 section

131, 141, 152, 161 (upstream) sub-section 132, 142, 152, 162 (downstream) sub-section

200 buildjob

201, 202, 203, 204 workpiece

210 build- job layer

Claims

1. Method for additiv e manufacturing, by means of a plurality of focused energy beams (102, 103, 104, 105), of a build-job (200) comprising one or more workpieces (201 , 202. 203, 204) in a layered manner from a powder provided in a powder bed (110), the method comprising:

Accessing a digital build job model for the buildjob (200) to be formed;

Determining, tor each of the focused energy beams (102, 103, 104, 105), of a respective section ( 130, 140. 150, 160) within a working area ( 120) of the powder bed (110), wherein each of the sections (130, 140, 150, 160) is determined based on a respective partial build-job amount calculated from a respective buildjob portion of the digital build-job model, in particular within the respective section (130, 140, 150, 160);

Providing a top powder layer (11 1) of the powder bed (110); and

Forming a build-job layer (210) by selectively consolidating powder of the top powder layer (111) by the focused energy beams (102, 103, 104, 105), whereby each of the focused energy beams ( 102. 103. 104. 105 ) operates within its respective section (130, 140, 150, 160).

2. The method of claim 1 , wherein for each section ( 130. 140. 150. 160) the respective partial buildjob amount is calculated as a partial mass to be consolidated or a partial area to be consolidated or a partial volume to be consolidated of the buildjob portion, in particular within the respective section (130, 140, 150, 160).

3. The method according to any one of the preceding claims, wherein the respective sections (130, 140, 150, 160) arc detennined by an optimization algorithm for obtaining substantially equal partial buildjob amounts in the sections (130, 140, 150, 160).

4. The method according to any one of the preceding claims, wherein the build-job portion of the digital build-job is determined as the intersection of at least a layer of the digital build-job model with the respective section ( 130, 140. 150, 160), preferably as the intersection of the digital build-job model with the respective section (130, 140, 150, 160).

5. The method according to an\ one of the preceding claims, wherein a plurality of build-job layers are formed on top of each other by repeating the steps of providing a top powder layer (111) of the powder bed (110); and of forming a build-job layer (210) by selectively consolidating powder of the top powder layer (111) by the focused energy beams (102, 103, 104, 105), wherein preferably (a) or (b):

(a): The respective sections (130, 140, 150, 160) for the focused energy beams (102, 103, 104, 105) are determined for each of the build-job layers indiv idually, wherein the build-job portion of the digital build-job model is detemiincd as the intersection of the respective one of the build-job layers of the digital build^job model with the respective section (130, 140, 150, 160); or

(b): The respective sections (130, 140, 150, 160) for the focused energy beams ( 102, 103, 104, 105) arc determined initially, wherein the build-job portion is determined as the intersection of the plurality of the build-job layers of the digital build-job model with the respective section (130, 140, 150, 160) for the plurality of layers.

6. The method according to any one of the preceding claims, wherein each of the sections ( 130, 140. 150. 160) arc non-intcrsccting and each abut against at least one adjacent section (130, 140, 150, 160); preferably along a major axis of the section (130, 140, 150, 160), the major axis extending parallel to a direction of inert gas flow (101) for removing debris.

7. The method according to any one of the preceding claims, wherein each section ( 130, 140, 150. 160) extends, in a length direction, over the entire length of the working area (120).

8. The method according to any one of the preceding claims, wherein the determining of the sections ( 130. 140, 150. 160) includes the determining of the width (W) of the sections (130, 140, 150, 160).

9. The method according to any one of the preceding claims, comprising:

Further subdividing the sections (130, 140, 150, 160) into sub-sections (131, 132, 141, 142, 151, 152, 161, 162), and whereby each of the focused energy beams (102, 103, 104, 105) operate within adjacent, preferably abutting, subsections (132, 142, 152, 162).

10. The method of the preceding claim, further comprising:

Determining a length (L) of each sub-section (131, 132, 141, 142, 151, 152, 161, 162) along the direction of inert gas flow (101) by an optimization algorithm for obtaining equal partial build^ob amounts in the sub-sections (131, 132, 141, 142, 151, 152, 161, 162).

11. The method according to any one of the preceding claims, further comprising the step:

Consolidating the contours of the build-job layer (210), preferably of each of the build-job layers (210), with one of the plurality of focused energy beams ( 102. 103. 104, 105) or by means of utilising each of the plurality of focused energy beams ( 102. 103. 104, 105 ) in the respective section ( 130. 140. 150. 160).

12. The method according to any one of the preceding claims, wherein the workpiece (201, 202, 203, 204) is a component of a turbomacliinery component, in particular a turbine component or a compressor component, such as a nozzle ring or a bladed turbine wheel or a bladed compressor wheel; and/or wherein the workpiece (201, 202, 203, 204) is non- rotationally symmetric.

13. The method according to any one of the preceding claims, wherein the build-job (200) comprises two or more workpieces (201 , 202. 203, 204).

14. The method of any one of the preceding claims, wherein the focused energy beam ( 102. 103. 104. 105) is one of a laser beam, an electron beam, an electric arc and a plasma arc, preferably wherein the focused energy beam is a laser beam.

15. Manufacturing apparatus for additive manufacturing of a build-job (200) comprising one or more workpieces ( 201 , 202. 203. 204} in a layered manner from a powder provided in a powder bed (110), the apparatus comprising: a powder bed (110); a powder layering device for providing a top powder layer (111) in the powder bed (1 10); a plurality of focused energy beam devices for producing respective focused energy beams ( 102. 103, 104, 105) capable of selectively consolidating the powder of the top powder layer (111); a controller for directing the focused energy beam devices, the controller comprising program code configured to instruct the controller to carry out the method of any one of claims 1 to 14.

16. Computer program comprising instructions which, when the program is executed by a computer, cause the computer to carry out the following steps of the method of claim 1:

Accessing a digital build-job model for a build-job (200) to be formed; and

Determining of a respective section (130, 140, 150, 160), for each of a plurality of focused energy beams (102, 103, 104, 105), within a working area (120), wherein each of the sections (130, 140, 150, 160) is determined based on a respective partial build-job amount calculated from a respective build-job portion of the digital build-job model within the respective section (130, 140, 150, 160).