METHOD FOR MANUFACTURING A PART EQUIPPED WITH A CYLINDRICAL HOLE BY DEPOSITION AND SOLIDIFICATION OF SUCCESSIVE LAYERS OF A POWDER AND PART OBTAINED BY THIS METHOD

Abstract

TITLE: METHOD FOR MANUFACTURING A PART PROVIDED WITH A CYLINDRICAL HOLE BY DEPOSITION AND SOLIDIFICATION OF SUCCESSIVE LAYERS OF A POWDER AND PART OBTAINED BY THIS METHOD One aspect of the invention relates to a method for manufacturing a part (10) by deposition and solidification of successive layers of a powder along a deposition axis Z, comprising a final cylindrical hole (30), characterized in that it comprises the following steps: deposition and solidification of successive layers of powder around a predefined area, the predefined area forming, after deposition and solidification of a final layer of powder, a construction hole (200), the construction hole (200) comprising a constant portion (210) and a temporary portion (220), andformation of the final hole (30), with an X axis perpendicular to the deposition axis Z, by deformation and collapse of the temporary portion (220) of the construction hole (200), the final hole (30) having a section in the shape of a circle C1.Figure to be published with the abstract: Figure 1.

Description

Title of the invention: METHOD FOR MANUFACTURING A PART PROVIDED WITH A CYLINDRICAL HOLE BY DEPOSITION AND SOLIDIFICATION OF SUCCESSIVE LAYERS OF A POWDER AND PIECE OBTAINED BY THIS PROCESS TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to the field of additive manufacturing and particularly to the powder bed laser fusion process.

[0002] The present invention relates more particularly to a method of manufacturing a part provided with a cylindrical hole by deposition and solidification of successive layers of a powder, and a part obtained by this method. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0003] The laser powder bed fusion process, or Laser Beam Melting (LBM) or Laser Metal Deposition (LMD) in English terminology, is an additive manufacturing technology, also called three-dimensional (3D) printing involving the use of a 3D printer.

[0004] The powder bed laser fusion process can be used for shaping metal parts, or polymer parts, depending on the technology selected. For example, direct metal laser sintering (DMLS) technology and electron beam melting (EBM) technology use metal powders such as aluminum, chromium, cobalt, etc. On the other hand, selective laser sintering (SLS) technology and multi-jet fusion (MJF) technology use polymer powders such as nylon and nylon loaded with glass or carbon fibers.These different technologies of the laser powder bed fusion process make it possible to manufacture three-dimensional parts by adding material, that is to say by depositing and solidifying successive layers of a powder. This type of process differs from so-called "conventional" manufacturing processes, according to which the manufacture of parts is carried out either by removing material called machining, or by plastic deformation of the material or by assembling several elements.

[0005] Conventionally, as shown in [Fig.l], the 3D printer used for producing a part 10 by laser fusion on a powder bed 7 is a machine 2 comprising: - a manufacturing tank 4 comprising a manufacturing plate 42 forming a base for the manufacturing of the part 10, the manufacturing plate 42 being movable in translation along a deposition axis Z, - a feed tray 5 for powder 7 arranged near the manufacturing tray 4 and comprising a bottom 52 movable in translation along the Z axis, - a scraper 6 movable in translation along a Y axis, perpendicular to the Z axis, on a first rail 22 of the machine 2, and - at least one laser 8 comprising a laser beam 82, the laser 8 being movable in translation along an X axis, perpendicular to the Z axis, and along the Y axis, on a second rail 24 of the machine 2.

[0006] The additive manufacturing of a part 10 requires the prior creation of a digital production file via suitable software comprising: • a cutting of the 3D model of the part into a plurality of slices having a predetermined thickness, and • the parameters of the laser 8 such as its power, the speed and scanning pattern of the laser beam 82, the thickness of the slices of the part 10 etc.

[0007] The method of manufacturing a part 10 by laser fusion on a powder bed comprises the following successive steps: - translation of the bottom 52 of the feed tray 5 along the Z axis, upwards, so as to obtain a raised quantity of powder 7, - translation of the bottom 42 of the manufacturing tank 4 along the Z axis, downwards, so as to obtain a free space above the powder bed 7 present in the manufacturing tank 4, - transfer by the scraper 6 of a quantity of powder 7 from the feed tank 5 to the manufacturing tank 4 and distribution of the powder 7 uniformly in the manufacturing tank 4 so as to create a new layer of powder 7 whose thickness is substantially equal to that of a slice of the part 10, - selective scanning by the laser beam 82 of the laser 8 of certain areas of the newly deposited powder layer 7 so as to fuse and solidify the powder particles to create a two-dimensional slice of the part 10, and - repeat the three previous steps until the final three-dimensional part 10 is obtained.

[0008] However, additive manufacturing by laser powder bed fusion does not allow the manufacture of an unsupported surface, called a "ceiling", due to the collapse of the unsupported surface when the part is subjected to gravity, i.e. when it is completely removed from the powder bed. Consequently, the formation of cylindrical holes, the axis of which extends perpendicular to the deposition axis Z, i.e. that is to say substantially horizontal, is not achievable. Indeed, at the highest point of a cylindrical hole, the surface is not supported and it collapses. Summary of the invention

[0009] The invention offers a solution to the problems mentioned above, by proposing a method for manufacturing a part by depositing and solidifying successive layers of a powder along a deposition axis Z, the part being provided with a cylindrical hole whose axis extends perpendicular to the deposition axis Z.

[0010] A first aspect of the invention relates to a method for manufacturing a part by depositing and solidifying successive layers of a powder along a deposition axis Z, comprising a cylindrical final hole. The manufacturing method comprises the following steps: - deposition and solidification of successive layers of powder around a predefined area, the predefined area forming, after deposition and solidification of a final layer of powder, a construction hole, the construction hole comprising a constant portion and a temporary portion, and - formation of the final hole, with axis X perpendicular to the deposition axis Z, by deformation and collapse of the temporary portion of the construction hole, the final hole having a cross-section in the shape of a circle CL

[0011] The “predefined zone” is a three-dimensional zone which extends along three axes X, Y and Z. This predefined zone corresponds to a volume intended to form the construction hole of the part, after deposition and solidification of all the layers of powder necessary for the construction of the part.

[0012] The manufacturing method according to the invention makes it possible, thanks to the formation of a construction hole during the production of a part produced using the laser powder bed fusion method, to program the production of a final cylindrical hole taking into account the deformation and collapse of the temporary portion of the construction hole.

[0013] Advantageously, the constant portion of the construction hole is arranged below the temporary portion of the construction hole, following the deposition axis orientation Z.

[0014] Preferably, the constant portion of the construction hole has a section comprising a lower arc of the circle C1 with center 01 and radius rl, and the temporary portion of the construction hole has a section comprising an upper arc of a circle C2 with center 02 and radius r2, and two junction sections each connecting the lower arc of the constant portion to the upper arc of the temporary portion of the construction hole.

[0015] Advantageously, the center 01 of the circle C1 and the center 02 of the circle C2 are aligned along the Z axis and spaced apart from each other by a distance L1.

[0016] Preferably, the radius r2 of the circle C2 is equal to the radius rl of the circle Cl.

[0017] Preferably, each junction section of the temporary portion is tangent to the lower arc of the constant portion of the construction hole and is tangent to the upper arc of the temporary portion of the construction hole.

[0018] According to a first embodiment of the invention, each junction section of the temporary portion of the construction hole comprises: - a connecting segment extending substantially along the Z axis and connected to the lower arc of the constant portion, - an intermediate segment connected to the upper arch of the temporary portion, and - an intermediate arc of a circle C3 with center 03 and radius r3 connecting the intermediate arc connecting segment.

[0019] Advantageously, each intermediate segment of each junction section of the temporary portion of the construction hole is tangent to the intermediate arc and is tangent to the upper arc of the temporary portion of the construction hole.

[0020] Preferably, the center 01 of the circle C1 and the center 03 of the circle C3 are aligned along the Z axis and spaced apart from each other by a distance L2, and the distance L2 is greater than the distance L1.

[0021] Advantageously, the radius r3 of the circle C3 is equal to the radius rl of the circle Cl.

[0022] Preferably, each intermediate segment of each junction section of the temporary portion of the construction hole forms an angle a, between 30° and 45°, with an axis Y passing through the center 02 of the circle C2 and perpendicular to the axis X and to the axis Z.

[0023] According to a second embodiment of the invention, each junction section of the temporary portion of the construction hole comprises a connecting segment extending substantially along the Z axis and connecting the lower arc of the constant portion to the upper arc of the temporary portion of the construction hole.

[0024] Advantageously, the step of depositing and solidifying successive layers of powder comprises a sub-step of forming at least one longitudinal wall extending from the lower arc of the constant portion to the upper arc of the temporary portion of the construction hole, each longitudinal wall extending parallel to an XZ plane. The presence of longitudinal walls makes it possible to support the temporary portion of the construction hole.

[0025] Preferably, the step of depositing and solidifying successive layers of powder comprises a sub-step of forming a normal wall extending from the lower arc of the constant portion to the upper arc of the temporary portion of the hole. construction, the normal wall extending parallel to a YZ plane. The presence of a normal wall increases the rigidity of the construction hole.

[0026] Advantageously, the sub-step of forming at least one wall forms a single normal wall to allow the circulation of a fluid inside the construction hole.

[0027] Preferably, the step of forming the final hole comprises a sub-step of dissolving the longitudinal walls and / or the normal wall of the construction hole.

[0028] A second aspect of the invention relates to a part produced by deposition and solidification of successive layers of a powder along a deposition axis Z. The part being obtained by the manufacturing method according to the invention. The final hole of the part is delimited along the deposition axis Z by a lower surface and an upper surface, the upper surface being unsupported and substantially arranged opposite the lower surface of the final hole.

[0029] Advantageously, the circularity of the lower surface of the final hole is substantially identical to the circularity of the lower surface of the lower arc of the construction hole, and the circularity of the upper surface of the final hole is lower than the circularity of the lower surface of the final hole.

[0030] The invention and its various applications will be better understood upon reading the following description and examining the accompanying figures. BRIEF DESCRIPTION OF THE FIGURES

[0031] Other advantages and characteristics of the invention will appear on reading the following description, illustrated by the figures in which: - [Fig.l], already described, is a schematic representation of a machine conventionally used for implementing a laser powder bed fusion process; - [Fig.2] is a sectional diagram along a YZ plane of a part in progress manufacturing carried out by a laser powder bed fusion process and comprising a construction hole according to a first embodiment of the invention; - [Fig.3] is a sectional diagram along a YZ plane of a part in progress manufacturing carried out by a laser powder bed fusion process and comprising a construction hole according to a second embodiment of the invention; - [Fig.4] is a perspective view in section along an XY plane of a part in manufacturing course comprising a construction hole according to the second embodiment of the invention; - [Fig.5] is a cross-sectional diagram of a final part produced by a laser powder bed fusion process and comprising a final hole according to the invention. DETAILED DESCRIPTION

[0032] An example of the manufacturing method according to the invention and of a part obtained by this method are described in detail below, with reference to the attached drawings. This example illustrates the characteristics and advantages of the invention.

[0033] Unless otherwise specified, the same element appearing in different figures has a single reference.

[0034] For the understanding of the invention, an orthogonal reference frame XYZ indicated in the figures will be adopted, according to which the X and Y axes extend in a horizontal plane and the Z axis extends in a vertical plane following the orientation in the figures. A lower portion towards an upper portion of a cylindrical end hole is oriented according to the Z axis of the XYZ reference frame.

[0035] In the description, the terms “lower” and “upper” are defined along the Z axis, for the same element, the “lower” part being located below the “upper” part.

[0036] Figures 2, 3 and 4 illustrate a part 10F in the process of being manufactured, produced by deposition and solidification of successive layers of a powder, along a deposition axis Z, and comprising a construction hole 200 extending along an axis X.

[0037] The part 10F being manufactured is delimited between a lower surface 12A and an upper surface 12B and comprises the construction hole 200 which is delimited between a low point 202 and a high point 204, along the Z axis.

[0038] More particularly, the part 10F being manufactured comprises: - a lower part 14F corresponding to the part of the part 10F located below the construction hole 200, that is to say the part extending from the lower surface 12A of the part 10F to the low point 202 of the construction hole 200, - a perforated part 16F corresponding to the part of the part 10F comprising the final hole 30, that is to say the part extending from the low point 202 of the construction hole 200 to the high point 204 of the construction hole 200, and - an upper part 18F corresponding to the part of the part 10F located above the construction hole 200, that is to say the part extending from the high point 204 of the construction hole 200 to the upper surface 12B of the part 10F.

[0039] As shown in Figures 2, 3 and 4, the construction hole 200 comprises a constant portion 210 and a temporary portion 220. A first embodiment of the construction hole 200 is shown in [Fig. 2] and a second embodiment of the construction hole 200 is shown in Figures 3 and 4. According to the first and second embodiments, the constant portion 210 of the construction hole 200 is arranged below the temporary portion 220 of the construction hole 200, following the orientation of the Z axis. The construction hole 200 is configured to form a final hole 30, illustrated in [Fig. 5], by deformation and collapse of the temporary portion 220 of the construction hole 200. The final hole 30 obtained is substantially identical for the first and second embodiments of the invention.

[0040] Preferably, the construction hole 200 is symmetrical with respect to the Z axis passing through the center 01 of the circle C1 and has a constant section along the X axis. More particularly, the construction hole 200 is delimited along the Z axis by a lower surface 206 and an upper surface 208, the upper surface 208 being unsupported and substantially arranged opposite the lower surface 206 of the construction hole 200.

[0041] The constant portion 210 of the construction hole 200 is identical for the first and second embodiments of the invention. More particularly, the constant portion 210 of the construction hole 200 has a section comprising a lower arc 212 of a circle C1 with center 01 and radius rl, delimited between a first end 212A and a second end 212B. Advantageously, the lower arc 212 forms a semicircle according to which the first and second ends 212A, 212B are aligned with the center 01 of the circle C1, along the Y axis.

[0042] The temporary portion 220 of the construction hole 200 has a section comprising: - an upper arc 222 of a circle C2 with center 02 and radius r2, delimited between a first end 222A and a second end 222B, and - a first junction section 230 connecting the first end 212A of the lower arc 212 of the constant portion 210 to the first end 222A of the upper arc 222 of the temporary portion 220, and - a second junction section 240 connecting the second end 212B of the lower arc 212 of the constant portion 210 to the second end 222B of the upper arc 222 of the temporary portion 220.

[0043] More particularly, the first joining section 230 of the temporary portion 220 of the construction hole 200 is arranged before the second joining section 240 of the temporary portion 220 of the construction hole 200, following the orientation of the Y axis.

[0044] As illustrated in Figures 2 and 3, the center 01 of the circle C1 and the center 02 of the circle C2 are aligned along the Z axis and spaced apart from each other by a distance LL. More particularly, the distance L1 corresponds to the number of layers of powder fused with the last layer spread, i.e. the layer of powder being melted, during manufacturing by laser powder bed fusion. Advantageously, the distance L1 is between 2 and 5 thicknesses of powder layers. Preferably, the radius r2 of the circle C2 is equal to the radius rl of the circle Cl. For example, the radii rl, r2 are between 0.6mm and 1.5mm.

[0045] According to the first embodiment of the invention as shown in [Fig.2]: - the first junction section 230 of the construction hole 200 has a section comprising: • a first connecting segment 232 extending substantially along the Z axis, delimited between a lower end 232A and an upper end 232B and connected to the first end 212A of the lower arc 212 at its lower end 232A, • a first intermediate arc 234 of a circle C3 with center 03 and radius r3, delimited between a lower end 234A and an upper end 234B, and connected to the first connecting segment 232 at its lower end 234A, and • a first intermediate segment 236 delimited between a lower end 236A and an upper end 236B, and connected to the upper end 234A of the first intermediate arc 234 at its lower end 236A, and connected to the first end 222A of the upper arc 222 of the temporary portion 220 at its upper end 236B; - the second junction section 240 of the construction hole 200 has a section comprising: • a second connecting segment 242, extending substantially along the Z axis, delimited between a lower end 242A and an upper end 242B and connected to the second end 212B of the lower arc 212 at its lower end 242A, • a second intermediate arc 244 of a circle C3 with center 03 and radius r3, delimited between a lower end 244A and an upper end 244B, and connected to the second connecting segment 224 at its lower end 244A, and • a second intermediate segment 246 delimited between a lower end 246A and an upper end 246B, and connected to the upper end 244A of the second intermediate arc 244 at its lower end 246A and connected to the second end 222B of the upper arc 222 of the temporary portion 220 at its upper end 246B.

[0046] The construction hole 200 according to the first embodiment of the invention has approximately an oblong shape comprising a tip formed by the upper arc 222 of the temporary portion 220.

[0047] As illustrated in [Fig.2], the center 01 of the circle C1 and the center 03 of the circle C3 are aligned along the Z axis and spaced apart from each other by a distance L2 greater than the distance L1. More particularly, the difference between the distance L1 and the distance L2 (L2-L1) corresponds to the number of temporary layers of powder, that is to say to the layers of powder intended to collapse during the formation of the final hole 30. Advantageously, the distance L2-L1 is between 1 and 5 thicknesses of layers of powder. Preferably, the radius r3 of the circle C3 is equal to the radius rl of the circle C1.

[0048] According to certain embodiments of the construction hole 200, the first connecting segment 232 of the first joining section 230 of the temporary portion 220 is tangent to the lower arc 212 of the constant portion 210 at its lower end 232A and is tangent to the intermediate arc 234 of the first joining section 230 at its upper end 232B. The first intermediate segment 236 of the first joining section 230 of the temporary portion 220 is tangent to the intermediate arc 234 of the first joining section 230 at its lower end 236A, and is tangent to the upper arc 222 of the temporary portion 220 at its upper end 236B. In addition, the second connecting segment 242 of the second joining section 240 of the temporary portion 220 is tangent to the lower arc 212 of the constant portion 210 at its lower end 242A and is tangent to the intermediate arc 244 of the second joining section 240 at its upper end 242B.The second intermediate segment 246 of the second joining section 240 of the temporary portion 220 is tangent to the intermediate arc 244 of the second joining section 240 at its lower end 246A, and is tangent to the upper arc 222 of the temporary portion 220 of the construction hole 200 at its upper end 246B.

[0049] Preferably, each of the first and second intermediate segments 236, 246 of each junction section 230, 240 of the temporary portion 220 of the construction hole 200 forms an angle α, between 30° and 45°, with the axis Y passing through the center 02 of the circle C2.

[0050] According to the second embodiment of the invention as shown in [Fig. 3]: - the first junction section 230 of the construction hole 200 has a section comprising a first connecting segment 232, extending substantially along the Z axis, delimited between a lower end 232A and an upper end 232B, and connected to the first end 212A of the lower arc 212 at its lower end 232A and connected to the second end 222B of the upper arc 222 of the temporary portion 220 at its upper end 232B, and - the second junction section 240 of the construction hole 200 has a section comprising a second connecting segment 242, extending substantially along the Z axis, delimited between a lower end 242A and an upper end 242B, and connected to the second end 212B of the lower arc 212 at its lower end 242A and connected to the second end 222B of the upper arc 222 of the temporary portion 220 at its upper end 242B.

[0051] The construction hole 200 according to the second embodiment of the invention has the shape of an oblong hole.

[0052] According to certain embodiments as shown in [Fig. 3], the construction hole 200 comprises a plurality of temporary thin longitudinal walls 260. More particularly, the construction hole 200 comprises at least one longitudinal wall 260 extending from the lower arc 212 of the constant portion 210 to the upper arc 222 of the temporary portion 220 of the construction hole 200. Each longitudinal wall 260 extends parallel to an XZ plane.

[0053] The longitudinal walls 260 are configured to support the temporary portion 220 of the construction hole 200 and more particularly the upper surface 208 of the temporary portion 220 of the construction hole 200. Each longitudinal wall 260 comprises a first wall 262 and a second wall 264 parallel and spaced apart from each other so as to form the thickness el of the longitudinal wall 260. Preferably, the thickness el of the longitudinal wall 260 is very small compared to the dimensions of the final hole 30. Preferably, the thickness el is between 0.06 mm and 0.12 mm, this value depending directly on the power of the laser previously configured. Indeed, for a thickness value el less than 0.06 mm, the manufacturability of the longitudinal wall 260 is very limited, and for a thickness value el greater than 0.12 mm, the flow of a fluid inside the manufacturing hole 200 is altered.According to an exemplary embodiment of the invention as shown in Figures 3 and 4, the construction hole comprises three longitudinal walls 260. Preferably, the longitudinal walls 260 are distributed along the Y axis and spaced apart from each other by a very small distance J compared to the dimensions of the final hole 30. Preferably, the distance J is between 0.05mm and 1mm. Indeed, for a value of the distance J less than 0.05mm, the flow of a fluid inside the manufacturing hole 200 is impaired, and for a value of the distance dl greater than 1mm, the capacity of the longitudinal walls to support the upper surface 208 of the temporary portion 220 of the construction hole 200. 260 is insufficient, which can cause collapse phenomena of the upper surface 208.

[0054] According to certain embodiments of the invention, the construction hole 200 comprises a temporary thin normal wall 270 extending from the lower arc 212 of the constant portion 210 to the upper arc 222 of the temporary portion 220 of the construction hole 200. As shown in [Fig. 4], the construction hole 200 comprises a single normal wall 270 extending in a median YZ plane of the cylindrical construction hole 200. The presence of a single normal wall 270 makes it possible to avoid the formation of dead cavities between the walls 1260, 270 of the construction hole 200, thus allowing the circulation of a fluid inside the construction hole 200.

[0055] The normal wall 270 is configured to reinforce the longitudinal walls 260 and thus improve the rigidity of the construction hole 200. The normal wall 270 comprises a first wall 272 and a second wall 274 parallel and spaced apart from each other so as to form the thickness e2 of the normal wall 270. Preferably, the thickness e2 of the normal wall 270 is very small compared to the dimensions of the final hole 30. Preferably, the thickness e2 is between 0.06 mm and 0.12 mm, this value depending directly on the power of the laser previously configured. Indeed, for a thickness value e2 less than 0.06 mm, the manufacturability of the normal wall 270 is very limited, and for a thickness value e2 greater than 0.12 mm, the flow of a fluid inside the construction hole 200 is altered.

[0056] According to certain embodiments, the first connecting segment 232 of the first joining section 230 of the temporary portion 220 of the construction hole 200 is tangent to the lower arc 212 of the constant portion 210 at its lower end 232A and is tangent to the upper arc 222 of the temporary portion 220 of the construction hole 200 at its upper end 232B. In addition, the second connecting segment 242 of the second joining section 240 of the temporary portion 220 of the construction hole 200 is tangent to the lower arc 212 of the constant portion 210 at its lower end 242A and is tangent to the upper arc 222 of the temporary portion 220 of the construction hole 200 at its upper end 242B.

[0057] The oblong shape of the construction hole 200 according to the second embodiment of the invention makes it possible to eliminate the distance L2, the number of temporary layers of powder therefore corresponds to the distance LL. Consequently, such a geometry requires the presence of longitudinal support walls 260 to limit the collapse of the unsupported upper surface 208 of the temporary portion 220 of the construction hole 200 and thus obtain a final hole 30 having satisfactory circularity.

[0058] As shown in [Fig.5], the final part 10 is delimited between a lower surface 12A and an upper surface 12B and comprises the final hole 30 delimited between a low point 32 and a high point 34, along the Z axis.

[0059] More particularly, the final part 10 comprises: - a lower part 14 corresponding to the part of the part 10 located below the final hole 30, that is to say the part extending from the lower surface 12A of the part 10 to the low point 32 of the final hole 30, - a perforated part 16 comprising the final hole 30, that is to say the part extending from the low point 32 of the final hole 30 to the high point 34 of the final hole 30, and - an upper part 18 corresponding to the part of the part 10 located above the final hole 30, that is to say the part extending from the high point 34 of the final hole 30 to the upper surface 12B of the part 10.

[0060] The lower part 14 of the final part 10 is substantially identical to the lower part 14 of the part 10F being manufactured. However, the perforated part 16 and the upper part 18 of the final part 10 are different from the perforated part 16F and the upper part 18F of the part 10F being manufactured because the latter will collapse during the formation of the final hole 30.

[0061] The final hole 30 is in the form of a cylindrical hole of axis X delimited along the axis Z by a lower surface 36 and an upper surface 38, the upper surface 38 being unsupported and substantially arranged opposite the lower surface 36 of the final hole 30. The final hole 30 has a cross-section in the shape of a constant circle C1 along the axis X. Preferably, the final hole 30 is symmetrical with respect to the axis Z passing through the center O1 of the circle C1.

[0062] Advantageously, the circularity of the lower surface 36 of the final hole 30 is substantially identical to the circularity of the lower surface 206 of the lower arc 210 of the construction hole 200. In addition, the circularity of the upper surface 38 of the final hole 30 is lower than the circularity of the lower surface 36 of the final hole 30. The circularity of a circle corresponds to the value obtained by dividing by 2 the difference between the maximum value of the diameter and the minimum value of the circle, the maximum and minimum values ​​being measured by carrying out 4 to 8 cuts of the circle according to its diameter.

[0063] The method for manufacturing a part 10, according to the first and second embodiments of the invention, comprises the following steps: - deposition and solidification of successive layers of powder along the deposition axis Z comprising the following sub-steps: formation of the lower part 12 of part 10, • formation of the perforated portion 16F of the part 10F during manufacture by deposition and solidification of successive layers of powder around a predefined zone, the predefined zone forming, after deposition and solidification of a final layer of powder, the constant portion 210 and the temporary portion 220 of the construction hole 200, and • formation of the upper part 18F of the part 10F during manufacture, - formation of the final hole 30 by deformation and collapse of the temporary portion 220 of the construction hole 200 including a sub-step of removal of the part 10F during manufacture from the powder bed.

[0064] The step of depositing and solidifying successive layers of powder corresponds to the laser powder bed fusion process, the manufacturing of the part 10F being manufactured being carried out in a manufacturing tank of a laser powder bed fusion machine.

[0065] During the step of forming the final hole 30 of the manufacturing method according to the first embodiment of the invention, the removal of the part 10F being manufactured from the powder bed involves the removal of the unfused powder present inside the build hole 200. The removal of the unfused powder then causes the temporary layers of powder to collapse and the inner surface 208 of the temporary portion 220 of the build hole 200 to move downward to form the upper surface 38 of the final hole 30. More particularly, the upper arc 222 and the intermediate segment 236 of the temporary portion 220 of the build hole 200 collapse by a distance substantially equal to the distance L2 so that the high point 204 of the build hole 200 reaches the high point 34 of the final hole 30 to form the upper portion 18 of the final part 10.The connecting segment 232 and the intermediate arc 234 collapse by a distance substantially equal to the distance L1 to form the perforated part 16 of the final part 10.

[0066] The last layer of powder corresponds to the layer of powder which closes the construction hole 200, that is to say the layer of powder deposited at the level of the high point 204 of the construction hole 200 or above the high point 204 of the construction hole 200.

[0067] The step of depositing and solidifying successive layers of powder of the manufacturing method according to the second embodiment of the invention comprises, before the sub-step of removing the part 10F from the powder bed, the following additional sub-steps: - formation of at least one longitudinal wall 260, and - formation of a normal wall 270.

[0068] The step of forming the final hole 30 of the manufacturing method according to the second embodiment of the invention comprises, after the sub-step of removing the part 10F from the powder bed, an additional sub-step of dissolving the longitudinal walls 260 and / or the normal wall 270 of the construction hole 200. The sub-step of dissolving the longitudinal walls 260 and / or the normal wall 270 is carried out by chemical etching by injecting a fluid, such as a chemical reagent, inside the manufacturing hole 200. The destruction of the longitudinal walls 260 and / or the normal wall 270 of the construction hole will cause the temporary layers of powder to collapse and the inner surface 208 of the temporary portion 220 of the construction hole 200 to move downwards to form the upper surface 38 of the final hole 30.More particularly, the upper arc 222 and the connecting segment 232 of the temporary portion 220 of the construction hole 200 collapse by a distance substantially equal to the distance L1 so that the high point 204 of the construction hole 200 becomes the high point 34 of the final hole 30 to form the holed portion 16 and the high portion 18 of the final part 10.

[0069] The method for manufacturing a part 10 according to the invention offers a solution for forming a final cylindrical hole 30 with an X axis perpendicular to the deposition axis Z using powder bed laser fusion technology. Indeed, the formation of a construction hole 200 comprising a temporary portion 220 having a particular geometry and then the deformation and collapse of the temporary portion 220 makes it possible to form a final cylindrical hole 30 having satisfactory circularity.

Claims

Claims

1. Method for manufacturing a part (10) by depositing and solidifying successive layers of a powder along a deposition axis Z, comprising a cylindrical final hole (30), characterized in that it comprises the following steps: - depositing and solidifying successive layers of powder around a predefined area, the predefined area forming, after deposition and solidification of a final layer of powder, a construction hole (200), the construction hole (200) comprising a constant portion (210) and a temporary portion (220), and - forming the final hole (30), with an axis X perpendicular to the deposition axis Z, by deformation and collapse of the temporary portion (220) of the construction hole (200), the final hole (30) having a cross-section in the shape of a circle Cl.

2. Manufacturing method according to claim 1, characterized in that: - the constant portion (210) of the construction hole (200) has a section comprising a lower arc (212) of the circle C1 with center 01 and radius rl, and - the temporary portion (220) of the construction hole (200) has a section comprising: • an upper arc (222) of a circle C2 with center 02 and radius r2, and • two junction sections (230, 240) each connecting the lower arc (212) of the constant portion (210) to the upper arc (222) of the temporary portion (220) of the construction hole (200).

3. Manufacturing method according to claim 2, characterized in that the center 01 of the circle C1 and the center 02 of the circle C2 are aligned along the Z axis and spaced apart from each other by a distance L1.

4. Manufacturing method according to claim 2 or 3, characterized in that the radius r2 of the circle C2 is equal to the radius rl of the circle Cl.

5. Manufacturing method according to any one of claims 2 to 4, characterized in that each joining section (230, 240) of the temporary portion (220) of the construction hole (200) comprises: - a connecting segment (232, 242) extending substantially along the Z axis and connected to the lower arc (212) of the constant portion (210), - an intermediate segment (236, 246) connected to the upper arc (222) of the temporary portion (220), and - an intermediate arc (234, 244) of a circle C3 with center 03 and radius r3 respectively connecting the connecting segment (232, 242) to the intermediate arc (236, 246).

6. Manufacturing method according to claim 5, characterized in that the center 01 of the circle C1 and the center 03 of the circle C3 are aligned along the Z axis and spaced apart from each other by a distance L2, and in that the distance L2 is greater than the distance L1.

7. Manufacturing method according to claim 5 or 6, characterized in that the radius r3 of the circle C3 is equal to the radius rl of the circle Cl.

8. Manufacturing method according to any one of the preceding claims in combination with claim 5, characterized in that each intermediate segment (232, 242) of each joining section (230, 240) of the temporary portion (220) of the construction hole (200) forms an angle a, between 30° and 45°, with an axis Y passing through the center 02 of the circle C2 and perpendicular to the axis X and to the axis Z.

9. Manufacturing method according to any one of claims 2 to 4, characterized in that each joining section (230, 240) of the temporary portion (220) of the construction hole (200) comprises a connecting segment (232, 242) extending substantially along the Z axis and connecting the lower arc (212) of the constant portion (210) to the upper arc (222) of the temporary portion (220) of the construction hole (200).

10. Manufacturing method according to any one of the preceding claims, characterized in that the step of depositing and solidifying successive layers of powder comprises a sub-step of forming at least one longitudinal wall (260) extending from the lower arc (212) of the constant portion (210) to the upper arc (222) of the temporary portion (220) of the construction hole (200), each longitudinal wall (260) extending parallel to an XZ plane.

11. Manufacturing method according to any one of the preceding claims, characterized in that the step of depositing and solidifying successive layers of powder comprises a sub-step of forming a normal wall (270) extending from the lower arc (212) of the constant portion (210) to the upper arc (222) of the temporary portion (220) of the construction hole (200), the normal wall (270) extending parallel to a YZ plane

12. Manufacturing method according to claim 10 or 11, characterized in that the step of forming the final hole (30) comprises a sub-step of dissolving the longitudinal walls (260) and / or the normal wall (270) of the construction hole (200).

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