Support for additive manufacturing of a part by laser powder bed fusion
Patent Information
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- SAFRAN ADDITIVE MFG CAMPUS
- Filing Date
- 2024-01-24
- Publication Date
- 2026-06-26
AI Technical Summary
Existing honeycomb structure supports in laser powder bed fusion manufacturing cause local overheating and potential machine stoppages during the production of complex parts with angles less than or equal to 90°, particularly those forming angles less than or equal to 45°, due to uniform cell sizes and high powder content, leading to surface degradation and dimensional non-conformities.
A support with a honeycomb structure featuring varying cell sizes and side wall densities, where the first portion has more side walls than the second portion, and optionally includes intermediate portions with decreasing side walls, to manage heat distribution and mechanical support effectively.
The varying honeycomb structure effectively reduces local overheating and prevents collapse of overhanging parts during manufacturing, ensuring improved surface conditions and preventing machine stoppages.
Abstract
Description
Title of the invention: Support for additive manufacturing of a part by laser fusion on a powder bed Technical field
[0001] The present invention relates to the manufacture of parts, in particular metal parts, by additive manufacturing and, more particularly, the manufacture of parts by laser fusion on a powder bed.
[0002] More specifically, the invention relates to a support for additive manufacturing of a part by laser fusion on a powder bed, an intermediate product, a method of manufacturing a part by laser fusion on a powder bed based on the use of such a support, as well as an intermediate product obtained in the context of such a method. Prior techniques
[0003] An existing method for manufacturing a metal part by additive manufacturing is the laser powder bed fusion process, more commonly known as the "LBM process", from the English abbreviation Laser Beam Melting. The LBM process consists of the selective consolidation of layers of metal powder in the air of a laser in order to constitute, slice by slice, a three-dimensional object. It can also be used for shaping polymers.
[0004] Manufacturing by the LBM process is computer-controlled. A digital file groups together all the laser trajectory instructions layer by layer allowing the production of the part.
[0005] A manufacturing plate serves as a base for manufacturing the part and a powder spreading device allows the spreading of a layer of powder of the desired material on the manufacturing plate with a desired thickness. This device can be a roller or a scraper which moves in translation on an axis on either side of the powder bed.
[0006] When the powder layer is deposited, one or more laser(s) selectively scan(s) certain areas of the powder bed, corresponding to a slice of the part to be produced. The scanning pattern as well as all the laser parameters, such as the laser power, the scanning speed, the spacing between two laser passes, etc. are dictated by the digital file.
[0007] Passing the laser over the powder bed raises the powder to a temperature above its melting temperature. A molten bath is thus created. As it cools, this bath consolidates and forms a solid metal bead. After laser scanning a layer of powder, a two-dimensional section of the desired part is obtained.
[0008] As the build plate descends, the powder spreading device deposits a new layer of powder on top of the previous one. A new laser scan is carried out in order to consolidate a new section of the part.
[0009] Thus, iteratively, a three-dimensional part is reconstituted by successive consolidation of two-dimensional sections.
[0010] Due to their architecture, areas of certain parts need to be maintained during their manufacture by the LBM process so that they do not collapse. Indeed, during the melting of these areas, the unconsolidated powder of the previous layers is not sufficient to ensure this maintenance.
[0011] It is known to generate, simultaneously with the manufacture of the part, a structure manufactured in one piece with the part, and providing support for these particular areas.
[0012] In particular, there are supports having a honeycomb structure formed by a plurality of intersecting side walls. Existing honeycomb structure supports are uniform and have a constant cell size over the entire height of the manufacturing plate up to the supported surface of the part.
[0013] However, when constructing a portion of the part extending in a plane forming an angle less than or equal to 90°, and particularly forming an angle less than or equal to 45°, relative to the plane passing through the manufacturing plate, the part overheats locally. In addition, the high quantity of powder contained in the cells of such a support does not make it possible to limit overheating.
[0014] The surface condition is then degraded, and there is also a risk of machine stoppage during manufacturing, such as a blockage of the scraper, or even a risk of dimensional non-conformity of the part. Statement of the invention
[0015] The present invention therefore aims to overcome the aforementioned drawbacks and to provide a method for manufacturing a part by powder bed fusion making it possible to reduce the phenomena of local overheating of complex portions of the part during their production.
[0016] The present invention relates to a support for additive manufacturing of a part by laser fusion on a powder bed, comprising a cellular structure comprising a plurality of side walls forming cells, said side walls extending from a first portion of the support comprising a first surface for supporting the part to a second portion of the support comprising a second surface opposite the first surface.
[0017] Furthermore, the first portion comprises a number of side walls greater than the number of side walls of the second portion so that the size of at least one part of the cells of the first portion according to a cross section perpendicular to the longitudinal axis of the cells is less than the size of the cells of the second portion.
[0018] Advantageously, the alveolar structure of the support may further comprise one or more intermediate portions positioned between said first and second portions, the number of side walls decreasing from the first portion to the second portion so that the size of the cells of each of the portions increases from the first portion to the second portion.
[0019] According to one characteristic, the cross-section of the honeycomb structure of the support may comprise a right-angled pattern according to which all or part of the side walls intersect to form right angles.
[0020] In one embodiment, the first and second portions of the honeycomb structure of the support may comprise a common pattern according to which all or part of the side walls intersect at right angles.
[0021] In one embodiment, the first portion, the second portion and the intermediate portion(s) of the honeycomb structure of the support may comprise a common pattern according to which all or part of the side walls intersect to form right angles.
[0022] In another embodiment, the cross-section of the first portion of the honeycomb structure of the support comprises at least two coexisting right-angled patterns, positioned offset from each other.
[0023] According to one embodiment, the cross-section of the first portion of the alveolar structure of the support comprises two coexisting right-angled patterns, positioned at an angle of 45° to each other and resulting in a plurality of triangular-shaped alveoli.
[0024] Preferably, the support comprises outer walls laterally delimiting the alveolar structure, the side walls each extending in a plane forming an angle other than 90° with the plane of each of the outer walls.
[0025] Preferably, the width of the cells of the first portion is between 0.4 and 5 mm, preferably between 0.6 and 2.5 mm, more preferably still between 0.8 and 1.5 mm.
[0026] The invention also relates to an intermediate product for additive manufacturing of a part by laser fusion on a powder bed, comprising the part and a support as previously described, the first surface of the support being connected to the part, and the support and the part being in one piece.
[0027] Advantageously, the intermediate product further comprises a manufacturing plate on which the part is manufactured, the second surface of the support being connected to the manufacturing plate, and the support, the part and the manufacturing plate being monobloc.
[0028] The invention also relates to a method for manufacturing a part by laser fusion on a powder bed comprising the formation of the part by layer-by-layer fusion of a powder using a laser and, simultaneously with the formation of the part, the formation of a support as previously described intended to support the part during its manufacture, the support and the part forming a single-piece assembly.
[0029] Preferably, the formation of the part by layer-by-layer fusion of the powder using a laser is carried out on a manufacturing plate.
[0030] Advantageously, the manufacturing method may comprise the separation of the part obtained from the support.
[0031] Advantageously, the manufacturing method may further comprise the separation of the part obtained from the manufacturing plate.
[0032] According to one characteristic, the decoupling can be carried out by machining, electroerosion and / or manual adjustment. Brief description of the drawings
[0033] The present invention will be better understood and other aims, advantages and characteristics will emerge from the detailed description which follows, comprising embodiments given purely for illustrative purposes and made with reference to the appended drawings, presented as non-limiting examples, which may serve to complete the understanding of the invention and the description of its implementation and, where appropriate, contribute to its definition, in which:
[0034] [Fig-1] is a schematic view of a part and a support manufactured by laser powder bed fusion according to an embodiment of the invention.
[0035] [Fig.2] illustrates the honeycomb structure of a part and a support manufactured by fusion powder bed laser according to one embodiment of the invention.
[0036] [Fig.3A], [Fig.3B], [Fig.3C] represent, respectively, the pattern of the first portion, of the intermediate portion and of the second portion of the support illustrated in [Fig.2],
[0037] [Fig.4] illustrates a pattern of a honeycomb structure of a support according to another mode of carrying out the invention.
[0038] [Fig.5] illustrates a pattern of a honeycomb structure of a support according to another mode of carrying out the invention.
[0039] [Fig.6] illustrates a pattern of a honeycomb structure of a support according to another mode of carrying out the invention.
[0040] It should be noted that, in the figures, the structural and / or functional elements common to the different embodiments may have the same references. Thus, unless otherwise stated, such elements have structural, dimensional properties. identical sional and material.
[0041] In the description of the invention which will be made, the expression "at least one" used must be considered as equivalent to the expression "one or more".
[0042] It is specified that the expression “between” used in the present description of the invention must be understood as including each of the limits mentioned. Detailed description of at least one embodiment
[0043] [Fig.l] illustrates a metal part 1 manufactured by a powder bed laser fusion manufacturing method according to one embodiment of the invention.
[0044] The manufacturing method comprises forming the part 1 by layer-by-layer melting of a metal powder. A manufacturing plate 2 serves as a base for manufacturing the part 1.
[0045] Simultaneously with the formation of the part 1, the manufacturing method comprises the formation by laser fusion on a powder bed of a support 3 intended to support the part during its manufacture.
[0046] Advantageously, a powder spreading device allows the spreading of a layer of metal powder on the manufacturing plate 2. The spreading device may be a roller or a scraper which moves in translation from one end to another of the manufacturing plate 2.
[0047] When the powder layer is deposited, a laser selectively scans certain areas of the powder bed, corresponding to a slice of the part 1 and the support 3 to be produced.
[0048] Passing the laser over the bed of metal powder allows the latter to be raised to a temperature above its melting temperature. A molten bath is thus created. As it cools, this bath consolidates and forms a solid metal bead. At the end of the laser scanning of a layer of powder, a two-dimensional section of the desired part 1 and support 3 is therefore obtained.
[0049] The layer of powder deposited makes it possible to form both the part 1 and the support 3.
[0050] As the manufacturing tray 2 descends, the spreading device powder deposits a new layer of powder on top of the previous one. A new laser scan is carried out in order to consolidate a new slice of part 1 and support 3.
[0051] The part 1 and the support 3 in three dimensions are thus formed by successive consolidation of sections in two dimensions.
[0052] The support 3 and the part 1 formed as well as the manufacturing plate 2 form a single-piece intermediate product.
[0053] Alternatively, the part 1 and the support 3 manufactured by the manufacturing method according to the invention may be made of a material other than metal, such as a polymer material, for example a composite polymer material.
[0054] The support 3 has a honeycomb structure. The honeycomb structure comprises a plurality of side walls forming cells.
[0055] The side walls extend from a portion 4 of the part 1, parallel to the plane passing through the manufacturing plate 2, and in the direction of the manufacturing plate 2, perpendicular to the plane passing through the manufacturing plate 2. In this way, the longitudinal axis of each cell extends perpendicular to the plane passing through the manufacturing plate 2.
[0056] The side walls of the honeycomb structure of the support 3 make it possible to support the part 1 during its manufacture.
[0057] The cells form channels in which the unfused powder of each layer remains.
[0058] In the example illustrated, the portion 4 of the part 1 from which the side walls extend is horizontal.
[0059] The honeycomb structure of the support 3 comprises a first portion 5 contiguous to the horizontal portion 4 of the part 1 and a second portion 6, opposite the first portion 5 along an axis perpendicular to the manufacturing plate 2, contiguous to the manufacturing plate 2.
[0060] The first portion 5 comprises a first surface 5a attached to the part 1, and in particular attached to the horizontal portion 4 in the example illustrated.
[0061] In the illustrated embodiment, the first surface 5a is an upper surface of the support 3.
[0062] In addition, the second portion 6 comprises a second surface 6a attached to the manufacturing plate 2, opposite the first surface 5a.
[0063] In the illustrated embodiment, the second surface 6a is a lower surface of the support 3.
[0064] With reference to [Fig.2], the number of side walls of the first portion 5 is greater than the number of side walls of the second portion 6. In this way, the resulting size of at least a part of the cells of the first portion is less than the size of the cells of the second portion 6.
[0065] The size of the cells is considered according to a cross section of the support 3, perpendicular to the longitudinal axis of the cells.
[0066] The architecture of the support 3 evolves between the horizontal portion 4 of the part 1 and the manufacturing plate 2.
[0067] The greater number of side walls in the first portion 5 contiguous to the horizontal portion 4 of the part 1 makes it possible to locally increase the density of the support 3 to better diffuse the heat produced by the fusion bath, which makes it possible to avoid overheating of the part 1 during its manufacture by laser fusion on a powder bed.
[0068] The number of upper side walls in the first portion 5 further maximizes the hanging and therefore the mechanical support of the part 1 on the support 3.
[0069] This makes it possible to avoid the collapse, during their construction, of portions of the part 1 in overhang, extending in a plane forming an angle less than or equal to 90° relative to the plane passing through the manufacturing plate 2, and in particular the portions extending in a plane forming an angle less than or equal to 45° particularly subject to collapse, and to improve the surface condition locally.
[0070] Furthermore, the evolution of the size of the cells by modification of the number of side walls makes it possible to have a variation of the cell size over the height of the support 3 without it being necessary to carry out an enlargement of the surface projected on the manufacturing plate 2 and an enlargement of the manufacturing plate 2.
[0071] As can be seen in [Fig.2], in the illustrated example, the support 3 further comprises an intermediate portion 7 positioned between the first and second portions 5 and 6. The intermediate portion 7 is contiguous to the first and second portions 5 and 6.
[0072] The number of side walls of the alveolar structure decreases from the first portion 5 to the second portion 6, passing through the intermediate portion 7, so that the size of the alveoli increases from the first portion 5 to the second portion 6, passing through the intermediate portion 7.
[0073] The first portion 5, the second portion 6 and the intermediate portion 7 form a single-piece assembly.
[0074] With reference to figures 3A, 3B and 3C illustrating, respectively, the pattern of the second portion 6, of the intermediate portion 7 and of the first portion 5, visible according to a cross section of the support 3 in the portion concerned.
[0075] In the illustrated example, the side walls of the second portion 6, of the intermediate portion 7 and of the first portion 5 are arranged so as to form a common pattern 8 according to which all or part of the side walls intersect to form right angles, like a grid.
[0076] The intermediate portion 7 has a greater number of side walls than the second portion 6 which is contiguous to the manufacturing plate 2. Additional side walls form an additional grid pattern 9. The additional side walls intersect to form right angles, which results, in the intermediate portion 7, in cells four times smaller than the cells of the second portion 6.
[0077] In addition, the first portion 5, in contact with the horizontal portion 4 of the part 1, has a number of side walls greater than that of the intermediate portion 7. Additional side walls form another additional grid pattern 10. The additional side walls intersect to form right angles, which results, in the first portion 5, in cells four times smaller than the cells of the intermediate portion 7.
[0078] The additional patterns 9 and 10 of the first portion 5 and of the intermediate portion 7 are formed by additional side walls strictly parallel or perpendicular to the side walls common with the second portion 6.
[0079] Alternatively, the additional patterns 9 and 10 of the first portion 5 and of the intermediate portion 7 may be formed by additional side walls which are not parallel or not perpendicular to the side walls common with the second portion 6.
[0080] In alternative embodiments, the first portion 5 contiguous to the part 1 may comprise two or more coexisting right-angled patterns. The coexistence of the patterns may result in the appearance of various shapes in the honeycomb structure considered along a transverse plane of the support 3, such as hexagonal, triangular, etc. honeycomb shapes.
[0081] In the example illustrated in Figures 4, 5 and 6, two coexisting right-angled patterns are positioned at an angle of 45° to each other and resulting in a plurality of triangular-shaped cells.
[0082] Given the 45° angle between the two coexisting patterns, several cell sizes coexist in the alveolar structure of the first portion 5.
[0083] The patterns of the alveolar structure of the first portion 5 can be chosen so as to limit overheating of the part 1 as much as possible, and in particular chosen according to the architecture of the portion of the part 1 forming a lower or equal angle relative to the manufacturing plate 2.
[0084] Preferably, the support 3 comprises external walls 3a, 3b delimiting the periphery of the cellular structure so that all the cells of the support are closed and retain all of the powder resulting from the manufacturing.
[0085] In the example illustrated, the side walls of the first portion 5, of the second portion 6 and of the intermediate portion 7 extend in a plane forming an angle other than 90° with the plane of each of the outer walls, so that the side walls and the outer walls are neither parallel nor perpendicular.
[0086] Preferably, the thickness of the walls of the alveolar structure is 2 mm maximum, more preferably between 0.05 and 2 mm.
[0087] Of course, the thickness value of the walls may be adjusted according to the nature of the support material and / or the nature and architecture of the part to be manufactured and supported.
[0088] Preferably, the width of the cells of the first portion is between 0.4 and 5 mm, preferably between 0.6 and 2.5 mm, more preferably still between 0.8 and 1.5 mm.
[0089] The manufacturing method according to the invention advantageously comprises a step of decoupling carried out on the intermediate product. Support 3 and manufacturing plate 2 are removed to recover part 1.
[0090] The decoupling can be carried out by machining, electroerosion and / or manual adjustment.
Claims
Claims
1. Support for additive manufacturing of a part (1) by laser fusion on a powder bed, comprising a cellular structure comprising a plurality of side walls forming cells, said side walls extending from a first portion (5) of the support (3) comprising a first surface (5a) for supporting the part (1) to a second portion (6) of the support comprising a second surface (6a) opposite the first surface (5a), characterized in that the first portion (5) comprises a number of side walls greater than the number of side walls of the second portion (6) so that the size of at least a portion of the cells of the first portion (5) according to a cross section perpendicular to the longitudinal axis of the cells is smaller than the size of the cells of the second portion (6).
2. Support according to claim 1, wherein the alveolar structure of the support (3) further comprises one or more intermediate portions (7) positioned between said first and second portions (5, 6), the number of side walls decreasing from the first portion (5) to the second portion (6) so that the size of the cells of each of the portions (5, 6, 7) increasing from the first portion (5) to the second portion (6).
3. A support according to claim 1 or 2, wherein the cross-section of the honeycomb structure of the support (3) comprises a right-angled pattern in which all or part of the side walls intersect at right angles.
4. Support according to claim 3, in which the first and second portions (5, 6) of the honeycomb structure of the support (3) comprise a common pattern according to which all or part of the side walls intersect to form right angles.
5. A support according to claim 3, wherein the cross-section of the first portion (5) of the honeycomb structure of the support (3) comprises at least two coexisting right-angled patterns positioned offset from each other, such as two coexisting right-angled patterns positioned at an angle of 45° and resulting in a plurality of triangular-shaped cells.
6. Support according to any one of the preceding claims, comprising outer walls (3a, 3b) laterally delimiting the cellular structure, the side walls each extending in a plane forming an angle other than 90° with the plane of each of the exterior walls (3a, 3b).
7. Support according to any one of the preceding claims, in which the width of the cells of the first portion (5) is between 0.4 and 5 mm, preferably between 0.6 and 2.5 mm, more preferably still between 0.8 and 1.5 mm.
8. Intermediate product for additive manufacturing of a part (1) by laser fusion on a powder bed, comprising the part (1) and a support (3) according to any one of claims 1 to 7, the first surface (5a) of the support (3) being connected to the part (1), and the support (3) and the part (1) being in one piece.
9. A method of manufacturing a part (1) by laser powder bed fusion comprising the formation of the part (1) by layer-by-layer fusion of a powder using a laser and, simultaneously with the formation of the part (1), the formation of a support (3) according to any one of claims 1 to 7 intended to support the part (1) during its manufacture, the support (3) and the part (1) forming a single-piece assembly.
10. Method according to claim 9, comprising the detachment of the part (1) obtained from the support (3), such as by machining, electroerosion and / or manual adjustment.