Method for manufacturing a part by means of a powder bed fusion additive manufacturing machine

Abstract

The invention relates to a method for manufacturing a part by means of a powder bed fusion additive manufacturing machine, characterised in that it comprises the following steps: executing a prescribed number of iterations which include: scanning (E3), by means of a heating beam, a subsequent powder zone (310i), located in the layer (30i) and comprising an edge (11) facing the edge (12) and a bridge (213, 313, 313i) which connects said edges and which is located on a volume (215i) of unfused powder, in order to fuse the zone (310i); cooling (E4) the zone (310i) that was fused, the bridges (313i) fused to each other being undercut and forming the outer undercut surface; after which at least one lower portion (110) of the edge (11) and at least one lower portion (120) of the edge (12) are removed (E5).

Description

[0001] DESCRIPTION

[0002] TITLE: Process for manufacturing a part using an additive manufacturing machine by powder bed fusion

[0003] The invention relates to a method for manufacturing a part by a powder bed fusion additive manufacturing machine, a computer program for implementing this method and a powder bed fusion additive manufacturing machine.

[0004] The field of the invention relates to the additive manufacturing of parts, also known as 3D printing.

[0005] We know of manufacturing processes for a part using an additive manufacturing machine by powder bed fusion, using supports to deposit layers of powder on them, in order to be able to produce parts with an undercut surface relative to the horizontal manufacturing platform, after removal of the supports.

[0006] These known methods have the following drawbacks.

[0007] In these known processes, the supports can represent a significant mass and volume, as well as a significant manufacturing time (especially for the development of the supports), and require finishing operations to remove the supports, as well as leveling of the surface of the manufactured part.

[0008] Furthermore, these known processes generate scrap of manufactured parts, which have been damaged due to support removal. Indeed, the remaining surface of the manufactured parts is often degraded by support removal.

[0009] Furthermore, people can injure themselves when removing the supports. Powder is often trapped in the supports, resulting in prolonged exposure of individuals to the powder, which can sometimes have carcinogenic, mutagenic, or reprotoxic effects (classified in this case as a CMR agent).

[0010] An objective of the invention is to obtain a process for manufacturing a part by a powder bed fusion additive manufacturing machine, a computer program to implement it and a powder bed fusion additive manufacturing machine, which overcome the disadvantages mentioned above.

[0011] To this end, a first object of the invention is a method for manufacturing a part by a powder bed fusion additive manufacturing machine, characterized in that the method comprises the following steps: execution of a prescribed number of iterations to form an undercut outer surface of the part, the prescribed number of iterations being greater than or equal to 2, each iteration comprising: the deposition, by the machine, of a subsequent layer of powder onto an underlying layer of powder, the scanning, by a heating beam emitted by the machine, of at least one subsequent zone of powder, which is located in the subsequent layer of powder and which includes a first anchor edge and a second anchor edge located opposite the first anchor edge, and a bridge, which connects the first anchor edge to the second anchor edge and which is located on a volume of unfused powder of the underlying layer of powder,To achieve the fusion of the next zone of powder into the next layer of powder, the next zone of powder having been fused, the first anchor edge, which has been fused into the layers, extending along at least one vertical component, the second anchor edge, which has been fused into the layers, extending along at least the vertical component, the bridges being fused to each other in the layers, the bridges being undercut relative to each other and forming the undercut outer surface, at least a lower part of the first anchor edge and at least a lower part of the second anchor edge being then removed.

[0012] Thanks to the invention, it is no longer necessary to have supports made of a material other than the powder itself in the additive manufacturing machine for depositing the powder layers that will form the undercut part onto these supports. The invention allows the anchoring edges to be manufactured by additive manufacturing within the machine, thus integrating the manufacturing of the anchoring edges into the part manufacturing process, thereby avoiding the drawbacks mentioned above. The anchoring edges are made of the same material as the part, which facilitates the removal of the lower portion of these edges to obtain the final part during finishing; this removal may, for example, involve machining operations.

[0013] According to one embodiment of the invention, the first anchoring edge has a first prescribed horizontal length, the second anchoring edge has a second prescribed horizontal length located opposite the first prescribed horizontal length.

[0014] According to one embodiment of the invention, the process comprises, before the prescribed number of iterations, the formation by the machine, by depositing several lower layers of powder, parts of which are fused and then successively cooled one on the other, of a lower part of the first anchoring edge and a lower part of the second anchoring edge, a lower volume of unfused powder extending between the lower part of the first anchoring edge and the lower part of the second anchoring edge along the first prescribed horizontal length and along the second prescribed horizontal length, the lower part of the first anchoring edge and the lower part of the second anchoring edge being removed after the prescribed number of iterations.

[0015] According to one embodiment of the invention, the prescribed number of iterations comprises a first iteration including: the deposition, by the machine, as the next layer of powder, of a first upper layer of powder on the lower part of the first anchoring edge, on the lower part of the second anchoring edge and on the lower volume of unfused powder located between these as an underlying layer of powder; the scanning, by the heating beam emitted by the machine, as the next zone of powder, of at least a first zone of powder, which is located in the first upper layer of powder and which comprises a first initial part covering along the first prescribed horizontal length the lower part of the first anchoring edge, a second initial part covering along the second prescribed horizontal length the lower part of the second anchoring edge,and as a bridge an initial bridge connecting the first initial part to the second initial part, the initial bridge being located on the lower volume of unfused powder and having a length smaller than the first prescribed horizontal length and the second prescribed horizontal length along the first anchoring edge and along the second anchoring edge, the sweep effecting the fusion of the first powder zone into the first upper layer of powder, the cooling, for the non-zero prescribed time, of the first powder zone having been fused.

[0016] According to one embodiment of the invention, the subsequent zone of powder having been fused during each iteration after the first iteration comprises: a first subsequent part, which covers along the first prescribed horizontal length a first underlying part, a second subsequent part, which covers along the second prescribed horizontal length a second underlying part, and as a bridge a subsequent bridge connecting the first subsequent part to the second subsequent part, the subsequent bridge being located on a volume of unfused powder of the underlying powder layer, a third subsequent part located on a third underlying part of the underlying powder layer, the underlying powder layer being initialized to the first upper powder layer, the first underlying part being initialized to the first initial part, the second underlying part being initialized to the second initial part,the third underlying part being initialized at the initial bridge.

[0017] According to one embodiment of the invention, the cooling, for the prescribed non-zero time, of the next zone of powder having been fused, is carried out to cause a greater tension of the bridge between the first anchoring edge and the second anchoring edge than during the fusion.

[0018] According to one embodiment of the invention, the cooling, for the prescribed non-zero time, of the first zone of powder having been fused is carried out to cause a greater tension of the initial bridge between the first initial part fixed on the lower part of the first anchoring edge and the second initial part fixed on the lower part of the second anchoring edge than during the melting.

[0019] According to one embodiment of the invention, the cooling, for a prescribed non-zero time, of the next zone of powder having been fused is carried out to cause a greater tension of the next bridge between the first next part fixed on the first underlying part and the second next part fixed on the second underlying part than during the fusion.

[0020] According to one embodiment of the invention, the scanning is performed by individual displacements of the heating beam, which is a laser beam, each individual displacement being carried out at a prescribed speed VL of the laser beam's movement in the layer along a prescribed distance Lv from the first anchor edge to the second anchor edge along a second horizontal direction, the laser beam having a prescribed width Ev along a first horizontal direction perpendicular to the second horizontal direction, so as to obtain an operating range, which is delimited in the plane (P e ,~ Pl ) by a polygon, formed by successive vertices having p' L V 'V F / the following coordinates: Mi (2; 35), M2 (15; 35), M3 (30°, 180), M4 (25; 180), M5 (10; 90) and Me (2; 90), where PL is a prescribed power of the laser beam,

[0021] Ep is the prescribed thickness of each layer,

[0022] V F ~ — Vl '

[0023] E v v s

[0024] Vs is a prescribed speed of advance of the laser beam from one individual displacement to the next, following a prescribed direction of advance along the first horizontal direction in each subsequent layer. a is a prescribed thermal diffusivity of the powder, the parameter -PL being expressed in J / mm², the Péclet number being dimensionless. According to one embodiment of the invention, the first anchoring edge is contained in a first vertical plane and / or the second anchoring edge is contained in a second vertical plane.

[0025] According to one embodiment of the invention, the first anchoring edge is curved in horizontal section view and / or the second anchoring edge is curved in horizontal section view.

[0026] According to one embodiment of the invention, the part is a turbomachine blade.

[0027] A second object of the invention is a computer program, comprising code instructions to control the steps of the manufacturing process of a part by a powder bed fusion additive manufacturing machine as described above, when implemented on a computer of the machine.

[0028] A third object of the invention is a machine for manufacturing a part by powder bed fusion, characterized in that the machine comprises means for performing the following steps: execution of a prescribed number of iterations to form an undercut outer surface of the part, the prescribed number of iterations being greater than or equal to 2, each iteration comprising: the deposition, by the machine, of a subsequent layer of powder onto an underlying layer of powder, the scanning, by a heating beam emitted by an emitter of the machine, of at least one subsequent zone of powder, which is located in the subsequent layer of powder and which comprises a first anchor edge and a second anchor edge located opposite the first anchor edge, and a bridge, which connects the first anchor edge to the second anchor edge and which is located on a volume of unfused powder of the underlying layer of powder,To achieve the fusion of the next powder zone into the next powder layer, the next powder zone, having been fused, is cooled for a prescribed non-zero time. The first anchor edge, which has been fused into the layers, extends along at least one vertical component, and the second anchor edge, which has been fused into the layers, also extends along at least the vertical component. The bridges are fused to each other within the layers, and the bridges are undercut relative to each other, forming the undercut outer surface.

[0029] The invention will be better understood upon reading the following description, given solely by way of non-limiting example with reference to the figures below in the accompanying drawings. [Fig. 1] represents a schematic vertical sectional view of an example of a portion of a part of Figure 16, produced by a manufacturing process using a powder bed fusion additive manufacturing machine according to an embodiment of the invention during a first stage.

[0030] [Fig. 2] represents a schematic top view of the example part of the part in Figure 16 produced by the manufacturing process using the additive manufacturing machine by powder bed fusion according to an embodiment of the invention during the first stage of Figure 1.

[0031] [Fig. 3] represents a schematic side section view of the example part of the part in Figure 16 produced by the manufacturing process using the additive manufacturing machine by powder bed fusion according to an embodiment of the invention during the first stage of Figure 1.

[0032] [Fig. 4] represents a schematic vertical section view of another part of the part of Figure 16, produced by the manufacturing process using an additive manufacturing machine by powder bed fusion according to an embodiment of the invention during a second stage.

[0033] [Fig. 5] represents a schematic top view of the example part of the part in Figure 16 produced by the manufacturing process using the additive manufacturing machine by powder bed fusion according to an embodiment of the invention during the second stage of Figure 4.

[0034] [Fig. 6] represents a schematic side section view of the example part of the part of Figure 16 produced by the manufacturing process by the additive manufacturing machine by powder bed fusion according to an embodiment of the invention during the second stage of Figure 4 in a third stage.

[0035] [Fig. 7] represents a schematic side section view of the example part of the part of Figure 16 produced by the manufacturing process by the additive manufacturing machine by powder bed fusion according to an embodiment of the invention during the second stage of Figure 4 in a fourth stage.

[0036] [Fig. 8] represents a schematic vertical section view of another part of the part of Figure 16, produced by the manufacturing process using a powder bed fusion additive manufacturing machine according to an embodiment of the invention during a third stage.

[0037] [Fig. 9] represents a schematic top view of the example of the part of the part of figure 16 produced by the manufacturing process by the additive manufacturing machine by powder bed fusion according to an embodiment of the invention during the third stage of figure 8.

[0038] [Fig. 10] shows a schematic side-section view of an example of the part shown in Figure 16 produced by the powder bed fusion additive manufacturing process according to an embodiment of the invention during the third stage of Figure 8 in a third step. [Fig. 11] shows a schematic side-section view of an example of the part shown in Figure 16 produced by the powder bed fusion additive manufacturing process according to an embodiment of the invention during the third stage of Figure 8 in a fourth step.

[0039] [Fig. 12] represents a schematic vertical section view of another part of the part of Figure 16, produced by the manufacturing process using a powder bed fusion additive manufacturing machine according to an embodiment of the invention during a fourth stage.

[0040] [Fig. 13] represents a schematic top view of the example of the part of the part of figure 16 produced by the manufacturing process by the additive manufacturing machine by powder bed fusion according to an embodiment of the invention during the fourth stage of figure 12.

[0041] [Fig. 14] represents a schematic side section view of the example part of the part of Figure 16 produced by the manufacturing process by the additive manufacturing machine by powder bed fusion according to an embodiment of the invention during the fourth stage of Figure 12 in a third step.

[0042] [Fig. 15] represents a schematic side section view of the example part of the part of Figure 16 produced by the manufacturing process by the additive manufacturing machine by powder bed fusion according to an embodiment of the invention during the fourth stage of Figure 12 in a fourth step.

[0043] [Fig. 16] represents a schematic vertical section view of the example of the final part obtained by the manufacturing process using the additive manufacturing machine by powder bed fusion according to an embodiment of the invention.

[0044] [Fig. 17] represents a schematic side view of the example part of figure 16 produced at the end of the manufacturing process steps by the powder bed fusion additive manufacturing machine according to an embodiment of the invention

[0045] [Fig. 18] represents a schematic view of top edges made according to another embodiment of the invention.

[0046] [Fig. 19] represents a schematic view of top edges made according to another embodiment of the invention.

[0047] [Fig. 20] represents a schematic view of top edges made according to another embodiment of the invention.

[0048] [Fig. 21] represents a schematic side section view of the example part of the part of Figure 16 produced by the manufacturing process using the additive manufacturing machine by powder bed fusion according to an embodiment of the invention during one of the stages in the fourth step.

[0049] [Fig. 22] represents an enlarged schematic top view of the example of the part of the part of figure 16 produced by the manufacturing process by the additive manufacturing machine by powder bed fusion according to an embodiment of the invention during the fourth stage of figure 12.

[0050] [Fig. 23] represents a diagram showing domains of a first parameter on the abscissa and of a second parameter on the ordinate, for the manufacturing process by the additive manufacturing machine by powder bed fusion according to an embodiment of the invention.

[0051] [Fig. 24] represents a flowchart of the manufacturing process by the additive manufacturing machine by powder bed fusion according to an embodiment of the invention.

[0052] An example of a manufacturing process for a part P by a 1000 additive manufacturing machine by powder bed fusion is described in more detail below with reference to figures 1 to 17 and 24.

[0053] The powder can be metallic, for example containing nickel or made of nickel, or containing titanium or made of titanium, or containing aluminum or made of aluminum.

[0054] According to one embodiment of the invention, the part P can be a turbomachine blade, such as for example a rotating turbomachine blower blade, or a low pressure compressor rotating blade, or a low pressure compressor fixed blade, or a high pressure compressor rotating blade, or a high pressure compressor fixed blade, or a low pressure turbine rotating blade, or a low pressure turbine fixed blade, or a high pressure turbine rotating blade, or a high pressure turbine fixed blade, or other.

[0055] The additive manufacturing process by powder bed fusion comprises the following steps El, described below with reference to figures 1 to 3.

[0056] During the El stages, the 1000 powder bed fusion additive manufacturing machine deposits several lower 10 layers of powder on top of each other.

[0057] During each step 11, after the deposition of each layer 10 of powder, the powder bed fusion additive manufacturing machine 1000 sweeps, with a heating beam emitted by a transmitter of the powder bed fusion additive manufacturing machine 1000, a portion 111 of a first anchor edge 11 and another portion 121 of a second anchor edge 12 into this layer 10. The second anchor edge 12 is located opposite the first anchor edge 11. The portion 111 of the first anchor edge 11 is located opposite the portion 121 of the second anchor edge 12. During this sweep, a lower volume 15 of unfused powder extends between part 111 of the first anchor edge 11 and part 121 of the second anchor edge 12 along the first prescribed horizontal length L1 of the first anchor edge 11 and along the second prescribed horizontal length L2 of the second anchor edge 12.The first prescribed horizontal length L1 of the first anchor edge 11 extends along a first horizontal and longitudinal direction X. The second prescribed horizontal length L2 of the second anchor edge 12 extends along the first horizontal and longitudinal direction X. The second prescribed horizontal length L2 of the second anchor edge 12 is located opposite the first prescribed horizontal length L1 of the first anchor edge 11. A non-zero distance along the second horizontal direction Y, perpendicular to the first horizontal direction X, exists between the first anchor edge 11 and the second anchor edge 12. The sweeping action of the heating beam emitted by the emitter of machine 1000 causes the fusion of portion 111 of the first anchor edge 11 and portion 121 of the second anchor edge 12 within the powder layer 10.After the scanning of part 111 of the first anchoring edge 11 and part 121 of the second anchoring edge 12, the powder bed fusion additive manufacturing machine 1000 cools for a prescribed non-zero time T, part 111 of the first anchoring edge 11 having been fused and part 121 of the second anchoring edge 12 having been fused.

[0058] Then, in another step El, another layer 10 of powder is deposited by the powder bed fusion additive manufacturing machine 1000 onto the previous layer 10 of powder, the portion 111 of the first anchoring edge 11 having been fused and cooled, and the previous portion 121 of the second anchoring edge 12 having been fused and cooled. In this other step El, the process described above for the previous step El is repeated to stack and fix another portion 111 of the first anchoring edge 11 onto the previous portion 111 of the first anchoring edge 11, and to stack and fix another portion 121 of the second anchoring edge 12 onto the previous portion 121 of the second anchoring edge 12.The powder bed fusion additive manufacturing machine 1000 stacks and fixes several parts 111 of the first anchoring edge 11 and several parts 121 of the second anchoring edge 12 onto one another, with the lower volume 15 of unfused powder extending between the parts 111 of the first anchoring edge 11 and the parts 121 of the second anchoring edge 12 along the first prescribed horizontal length L1 and along the second prescribed horizontal length L2. These parts 111 of the first anchoring edge 11 form a lower part 110 of the first anchoring edge 11. These parts 121 of the second anchoring edge 12 subsequently form a lower part 120 of the second anchoring edge 12.

[0059] After steps El, the machine 1000 executes a prescribed number N of iterations i to form an undercut outer surface 31 of the part P. The prescribed number N of iterations i is prescribed and is greater than or equal to 2.

[0060] Each iteration i comprises the following steps. For example, the first iteration performed for i=l is described with reference to figures 4 to 7.

[0061] During the first iteration, the powder bed fusion additive manufacturing machine 1000 deposits, during step E2, a first upper layer 20 of powder on the lower part 110 of the first anchor edge 11, on the lower part 120 of the second anchor edge 12 and on the lower volume 15 of unfused powder, which is located between the lower part 110 of the first anchor edge 11 and the lower part 120 of the second anchor edge 12.

[0062] Then, during the first iteration, the powder bed fusion additive manufacturing machine 1000 sweeps, during step E3, with the heating beam emitted by the machine 1000, one (or more) first zone 210 of powder, which is located in the first upper layer 20 of powder. This first zone 210 of powder, swept by the heating beam emitted by the emitter of the machine 1000, comprises a first initial part 211, which covers along the first prescribed horizontal length L1 the lower part 110 of the first anchoring edge 11, and a second initial part 212, which covers along the second prescribed horizontal length L2 the lower part 120 of the second anchoring edge 12.This first zone 210 of powder, swept by the heating beam emitted by the emitter of machine 1000, further includes an initial bridge 213, which connects the first initial part 211 to the second initial part 212 and is located on the lower volume 15 of unfused powder. The initial bridge 213 has, along the first direction X, a shorter length than the first prescribed horizontal length L1 along the first anchoring edge 11 and than the second prescribed horizontal length L2 along the second anchoring edge 12. The sweeping of the heating beam emitted by the emitter of machine 1000 over the first zone 210 of powder causes the first zone 210 of powder to fuse into the first upper layer 20 of powder.

[0063] During this scan in step E3 of the first iteration, a lower volume 215 of unfused powder extends into the first upper layer 20 of powder, next to the initial bridge 213, between the first initial portion 211 of the first anchor edge 11 and the second initial portion 212 of the second anchor edge 12 along the first prescribed horizontal length L1 of the first anchor edge 11 and along the second prescribed horizontal length L2 of the second anchor edge 12. A non-zero distance along the second horizontal direction Y, perpendicular to the first horizontal direction X, exists between the first initial portion 211 of the first anchor edge 11 and the second initial portion 212 of the second anchor edge 12.

[0064] Then, during the first iteration, the powder bed fusion additive manufacturing machine 1000 cools, during step E4, for the prescribed non-zero time T, the first zone 210 of powder having been fused.

[0065] For example, with reference to figures 8 to 11, the second iteration carried out for i=2 is described. During the second iteration, the 1000 powder bed fusion additive manufacturing machine deposits, during step E2, a subsequent layer 30 of powder on the first upper layer 20 of powder.

[0066] Then, during the second iteration, the powder bed fusion additive manufacturing machine 1000 sweeps, during step E3, with the heating beam emitted by the emitter of the powder bed fusion additive manufacturing machine 1000, one (or more) subsequent zone 310 of powder, which is located in the subsequent layer 30 of powder. This subsequent zone 310 of powder, swept by the heating beam emitted by the emitter of the machine 1000, comprises a first subsequent part 311 of the first anchoring edge 11 and a second subsequent part 312 of the second anchoring edge 12, which is located opposite the first subsequent part 311 of the first anchoring edge 11.This subsequent zone 310 of powder, swept by the heating beam emitted by the emitter of machine 1000, further includes a bridge 313, which connects the first subsequent part 311 to the second subsequent part 312 and which is located on the volume 215 of unfused powder of the underlying layer 20 of powder. The sweeping of the heating beam emitted by the emitter of machine 1000 over the subsequent zone 310 of powder causes the subsequent zone 310 of powder to fuse into the subsequent layer 30 of powder.

[0067] During this sweep in step E3 of the second iteration, a lower volume 315 of unfused powder extends into the next powder zone 310, next to the bridge 313, between the first next portion 311 of the first anchor edge 11 and the second next portion 312 of the second anchor edge 12 along the first prescribed horizontal length L1 of the first anchor edge 11 and along the second prescribed horizontal length L2 of the second anchor edge 12. A non-zero distance along the second horizontal direction Y, perpendicular to the first horizontal direction X, exists between the first next portion 311 of the first anchor edge 11 and the second next portion 312 of the second anchor edge 12.

[0068] Then, during the second iteration, the powder bed fusion additive manufacturing machine 1000 cooled, during step E4, for the prescribed non-zero time T, the next area 310 of powder having been fused.

[0069] The first anchor edge 11, which has been merged into layers 20, 30, extends along at least one vertical component Z. The second anchor edge 12, which has been merged into layers 20, 30, extends along at least the vertical component Z.

[0070] Bridge 213 and bridge 313 are fused together in layers 20, 30. Bridge 213 and bridge 313 are undercut from each other and form the undercut outer surface 31.

[0071] According to one embodiment of the invention, the subsequent zone 310 of powder having been fused during the second iteration subsequent to the first iteration (i=l) comprises: the first subsequent part 311, which covers along the first prescribed horizontal length L1 a first underlying part formed by the first initial part 211, the second subsequent part 312, which covers along the second prescribed horizontal length L2 a second underlying part formed by the second initial part 212, and the bridge 313, a third subsequent part 314 located on a third underlying part, formed by the initial bridge 213 of the underlying layer 20 of powder.

[0072] For example, with reference to figures 12 to 15, we describe the i-th iteration i performed for i greater than or equal to 2.

[0073] During the i-th iteration i, the powder bed fusion additive manufacturing machine 1000 deposits, during step E2, a next layer 30i of powder on the underlying layer 20i of powder.

[0074] Then, during the i-th iteration i, the powder bed fusion additive manufacturing machine 1000, during step E3, sweeps with the heating beam emitted by the emitter of the powder bed fusion additive manufacturing machine 1000, one (or more) subsequent zone 31 Oi of powder, which is located in the subsequent layer 30i of powder. This subsequent zone 31 Oi of powder, swept by the heating beam emitted by the emitter of the machine 1000, comprises a first subsequent part 31 li of the first anchoring edge 11 and a second subsequent part 312i of the second anchoring edge 12, which is located opposite the first subsequent part 31 li of the first anchoring edge 11.This subsequent zone 31 Oi of powder, swept by the heating beam emitted by the emitter of machine 1000, further includes a bridge 313i, which connects the first subsequent part 31 li to the second subsequent part 312i and which is located on the volume 215i of unfused powder of the underlying layer 20i of powder. The sweeping of the heating beam emitted by the emitter of machine 1000 over the subsequent zone 31 Oi of powder causes the subsequent zone 31 Oi of powder to fuse into the subsequent layer 30i of powder.

[0075] During this sweep in step E3 of the i-th iteration i, a volume 315i of unfused powder extends into the next powder zone 310, next to the bridge 313i, between the first next portion 31li of the first anchor edge 11 and the second next portion 312i of the second anchor edge 12 along the first prescribed horizontal length LI of the first anchor edge 11 and along the second prescribed horizontal length L2 of the second anchor edge 12. A non-zero distance along the second horizontal direction Y, perpendicular to the first horizontal direction X, exists between the first next portion 31li of the first anchor edge 11 and the second next portion 312i of the second anchor edge 12. Then, during the i-th iteration, the 1000 powder bed fusion additive manufacturing machine cools, during step E4, for the prescribed non-zero time T, the next 31 Oi zone of powder having been fused.

[0076] The first anchor edge 11, which was merged into layers 20, 30, 20i, 30i extends along at least one vertical component Z. The second anchor edge 12, which was merged into layers 20, 30, 20i, 30i extends along at least the vertical component Z.

[0077] The underlying bridge 213i of the underlying zone 21 Oi of powder of the underlying layer 20i of powder and the bridge 313i of the next zone 31 Oi of powder of the next layer 30i of powder are fused to each other in layers 20i, 30i. The bridge 213i and the bridge 313i are undercut with respect to each other and form the undercut outer surface 31.

[0078] According to one embodiment of the invention, the subsequent zone 310i of powder, having been fused during each iteration i subsequent to the first iteration, comprises: the first subsequent part 31li, which covers along the first prescribed horizontal length L1 a first underlying part 21li fused from the first anchoring edge 11 in the underlying layer 20i of powder; the second subsequent part 312i, which covers along the second prescribed horizontal length L2 a second underlying part 212i fused from the second anchoring edge 12 in the underlying layer 20i of powder; the subsequent bridge 313i; a third subsequent part 314i situated on a third underlying part 213i of the underlying layer 20i of powder, the underlying layer 20i of powder being initialized to the first upper layer 20 of powder; and the first underlying part 21li being initialized to the first initial part. 211,the second underlying part 212i being initialized to the second initial part 212, the third underlying part 213i being initialized to the initial bridge 213.

[0079] According to one embodiment of the invention, during step E4, a computer 1001 of the machine 1000 determines whether the number i of iterations carried out in step E4 is greater than or equal to the number N. In the negative, that is to say when the computer 1001 of the machine 1000 has determined that the number of iterations i carried out has reached the number N in step E4 is less than N, the process makes the machine 1000 return to step E2 to carry out a next iteration i+1 (i being replaced by i+1).

[0080] The computer 1001 may be or include one or more computers, one or more processors, one or more microprocessors, one or more control circuits, or other components. The computer 1001 may have been programmed by a computer program containing code instructions for implementing the process when it is implemented on this computer 1001 of the powder bed fusion additive manufacturing machine 1000.

[0081] In the example of figures 1 to 15, the N iterations i result for example in figures 16 and 17, including the final part P (the unfused powder is not shown in figure 16).

[0082] According to one embodiment of the invention, during step E5, after N iterations i (i.e., when the computer 1001 of the machine 1000 has determined that the number of iterations i performed has reached the number N in step E4), the lower part 110 of the first anchoring edge 11 and the lower part 120 of the second anchoring edge 12, or more parts of the first anchoring edge 11 and the second anchoring edge 12, are removed. Part P is thus obtained in step E5.

[0083] According to one embodiment of the invention, the first anchoring edge 11 and the lower part 110 of the first anchoring edge 11 are straight, as shown by way of example in Figures 1 to 17. According to one embodiment of the invention, the first anchoring edge 11 and the lower part 110 of the first anchoring edge 11 are included in a first vertical plane, as shown by way of example in Figures 1 to 17.

[0084] According to one embodiment of the invention, the second anchoring edge 11 and the lower part 120 of the second anchoring edge 12 are straight, as shown by way of example in Figures 1 to 17. According to one embodiment of the invention, the second anchoring edge 11 and the lower part 120 of the second anchoring edge 12 are included in a second vertical plane, as shown by way of example in Figures 1 to 17.

[0085] According to another embodiment of the invention, the first anchoring edge 11 is curved in horizontal section view and / or the second anchoring edge 12 is curved in horizontal section view, as shown by way of example in figures 19 and 20.

[0086] The machine 1000 for manufacturing a part P by powder bed fusion includes means for performing the following steps: executing a prescribed number of iterations i to form an undercut outer surface 31, 313 of the part P, the prescribed number N of iterations i being greater than or equal to 2, each iteration i comprising: the deposition E2, by the machine 1000, of a subsequent layer 30 of powder onto an underlying layer 20 of powder; the scanning E3, by a heating beam emitted by an emitter of the machine 1000, of at least one subsequent zone 310 of powder, which is located in the subsequent layer 30 of powder and which includes a first anchor edge 11 and a second anchor edge 12 situated opposite the first anchor edge 11, and a bridge 313, which connects the first anchor edge 11 to the second anchor edge 12 and which is located on a volume 215 of unfused powder from the underlying layer 20 of powder,to achieve the fusion of the next zone 310 of powder into the next layer 30 of powder, the cooling E4, for a prescribed non-zero time T, of the next zone 310 of powder having been fused, the first anchor edge 11, which has been fused into the layers 20, 30, extending along at least one vertical component z, the second anchor edge 12, which has been fused into the layers 20, 30, extending along at least the vertical component z, the bridges 313 being fused to each other in the layers 20, 30, the bridges 313 being undercut to each other and forming the undercut outer surface 31, 313.

[0087] The powder zones 210, 21 Oi, 310, 31 Oi are considered throughout the thickness of the powder layer along the vertical Z direction.

[0088] In each subsequent layer 30, 30i of powder, the third subsequent part 314, 314i and the bridge 313i, 313, located in the next zone 310, 310i of powder fused between the first anchor edge 11 and the second anchor edge 12 can have, upstream of the bridge 313, 313i along the direction S2 of the first horizontal X direction, a length L along the first horizontal X direction, which increases when going from bottom to top along the vertical Z direction as shown in Figure 12, or a length which increases then decreases when going from bottom to top along the vertical Z direction.

[0089] According to a first embodiment of the invention, the cooling, during step E4 for a non-zero prescribed time T, of the next zone 310 of powder that has been fused, is carried out to induce a greater tension in the bridge 313 between the first anchoring edge 11 and the second anchoring edge 12 than during the melting process. Thus, the powder bridge 313 heated during the scanning step E3 contracts and tightens as it cools during step E4.

[0090] According to a second embodiment of the invention, the cooling during step E4 for the prescribed non-zero time T of the first zone 210 of powder having been fused is carried out to cause a greater tension of the initial bridge 213 between the first initial part 211 fixed on the lower part 110 of the first anchoring edge 11 and the second initial part 212 fixed on the lower part 120 of the second anchoring edge 12 than during the fusion.

[0091] According to a third embodiment of the invention, the cooling during step E4 for the prescribed non-zero time T of the next zone 310 of powder having been fused is carried out to cause a greater tension of the next bridge (313, 313i) between the first next part 311 fixed on the first underlying part 211 and the second next part 312 fixed on the second underlying part 212 than during the fusion.

[0092] The powder bridge 213, 313, 313i forming the outer surface 31 provides sufficient mechanical strength resulting from the tension of this bridge 213, 313, 313i to ensure the manufacture of part P. The volume of material generated by the use of this bridge 213, 313, 313i is part of the machining allowances already provided for the machined blank. The use of this bridge 213, 313, 313i therefore does not require any additional finishing step. The tensioned bridge 213, 313, 313i serves as a support on which the part can be built. The tensioned bridge 213, 313, 313i serves as a support for the subsequent layers 30, 30i (third subsequent layer 314, 314i).

[0093] According to one embodiment of the invention, the heating beam of the powder bed fusion additive manufacturing machine 1000 is a laser beam having a prescribed width Ev along the first horizontal X direction perpendicular to the second horizontal Y direction. This prescribed width Ev is therefore the width of the bridge 213, 313, 313i along the first horizontal X direction. The scanning process involves an individual displacement of the laser beam along a prescribed distance Lv from the first anchor edge 11 to the second anchor edge 12 along the second horizontal Y direction. This individual displacement of the laser beam is thus performed to form the bridge 213, 313, 313i in each layer 20, 30, 30i. Each individual displacement of the laser beam from the first anchor edge 11 to the second anchor edge 12 is performed at a prescribed velocity VL.Each individual displacement of the laser beam could also make a round trip between the first anchor edge 11 and the second anchor edge 12. The laser beam forms, through further displacements, the edges 11 and 12 in each layer 10, 20, 30, 20i, 30i.

[0094] According to the embodiment of the invention, the scanning of each subsequent third part 314, 314i is performed by several individual movements of the laser beam, which are carried out one after the other side by side, offset by the prescribed width Ev along the SI direction of advancement (opposite to the S2 direction) towards the bridge 213, 313, 313i in each layer 20, 30, 30i along the first horizontal X direction. Each scan therefore ends with the last individual movement of the laser beam forming the bridge 213, 313, 313i in each layer 20, 30, 30i. We denote Vs the prescribed speed of advance of the individual displacements of the laser beam along the first horizontal X direction in each layer 30, 30i following the SI direction of advancement along the first horizontal X direction, that is to say the speed Vs of jump of the laser beam in each layer 30, 3 Oi following the SI direction of advancement along the first horizontal X direction.This type of scanning therefore creates a thermal front in each subsequent third section 314, 314i and then in the bridge 313, 313i during step E3 with each individual movement of the laser beam. Due to the successive individual movements of the laser beam in each scan, this thermal front, located between the first anchor edge 11 and the second anchor edge 12, moves in each subsequent third section 314, 314i in the SI direction of advance, including as far as the bridge 213, 313, 313i, in each layer 20, 30, 30i. The cooling of the thermal front when it is located at the bridge 313, 313i in step E4 causes this bridge 313, 313i to become energized. This thermal front allows for the creation of a homogeneous residual outer surface 31. Bridges 213, 313, 313i can form a kind of stair tread on which the geometry can be grown vertically (parts 314, 314i mentioned above).The thermal front represents, at each individual displacement of the laser beam during step E3, a boundary between the fused and unfused powder in each layer 30, 20i, 30i. This boundary is represented in Figure 22 by the bridge 313, 313i being fused in layer 30, 30i during the last individual displacement of the laser beam forming the bridge 213, 313, 313i. Upstream (in the S2 direction) of the fusing bridge 313, 313i is the subsequent third part 314, 314i being cooled. Downstream (in the SI direction) of the fusing bridge 313, 313i is the bed of unfused powder (volume 315, 315i of unfused powder).

[0095] The laser spot D L can have a diameter between 10 pm and 2 mm, notably between 40 pm and 500 pm in diameter.

[0096] According to one embodiment of this example of the invention, an operating range is delimited in the plane (P e ,~P L V l 'V F / ) by the interior and sides of a polygon, formed by the successive vertices p' having the following coordinates: Mi (2; 35), M2 (15; 35), M3 (30°, 180), M4 (25; 180), M5 (10; 90) and Me (2; 90), where

[0097] PL is the prescribed power of the laser beam (expressed in Watts),

[0098] E p is the prescribed thickness of each layer, a is a prescribed thermal diffusivity of the powder, p L has the parameter E L y being expressed in J / mm², the number of Péclet is dimensionless.

[0099] This polygon is delimited by its 6 sides (segments) joining successive vertices, namely the 6 sides [Mi M2], [M2M3], [M3M4], [M4 M5], [M5M6] and [M6Mi],

[0100] This embodiment provides the first, second, and third modes. This embodiment is illustrated in Figure 23, where the operating range of the aforementioned P values ​​is shown. e on the x-axis and values ​​of — Pl "The ordinates are located within the Ep-LyVp domains L and L. The description of domains L, 1b, 11, HI, IV and V of the first parameter P e on the x-axis and the second parameter Pl The ordinates of figure 23 are as follows. [Table 1]

[0101] The boundary (thermal front with vertical cross-section Lv.Ep) moves almost continuously at the virtual velocity VF mentioned above, in the case where both VF is sufficiently large by Vc compared to VL, (which is the case for example for a ratio — V of the order of 5 to 10), and Lv is sufficiently large compared to Ev (which is the case for example for a ratio — of the order of 300).

[0102] E v

[0103] In the above, we also note E p The penetration depth of the thermal front into the underlying powder. As a first approximation, this depth is equal to the thickness of a powder layer. In the case of Inconel 718 as the powder, an optimal operating point of the tension bridge

[0104] 213, 313, 313i can be obtained, for example, with the pair (Le ; — Ep' —Ly —Vp ) = (8.9 ; 60), corresponding to a laser power P L 80 W, E v = 0.037 mm, a powder bed thickness E p 40 pm of each layer, a speed V L of 900 mm / s, an assumed jump velocity Vs of 5000 mm / s, and calculated with a distance L v of 20 mm and a thermal diffusivity taken at 3.710 -6 m 2 / s. This operating point is given for a laser spot D Lbetween 40 pm and 500 pm in diameter. In case of a change in laser spot diameter (by changing the machine or by using a different laser within the same machine), a new operating point can be found using the procedure described above.

[0105] This operating point is also valid for other nickel-based superalloys with similar thermal properties.

[0106] Also, this operating point is not unique. Other values ​​are likely to be found within a range of parameters such as P L is between 80 W and 120 W, E v is between 0.037 mm and 0.11 mm, a speed V L of 900 mm / s, a laser spot diameter between 40 pm and 500 pm.

[0107] The cooling time T can be, for example, at least 3 seconds between each layer. This time depends on the geometry's ability to dissipate heat.

[0108] Of course, the operating range described above can be applied to nickel-based powder, including Inconel 718, or to a powder other than nickel, or to a powder other than Inconel 718.

[0109] In one embodiment of the invention, as shown by way of example in Figures 19 and 20, a rotation of the direction D of the individual displacements between successive layers 20i, 30i around a vertical axis can be performed for some of them, for example for at most ten layers 30i. For example, this direction D makes an angle of 90° with the edges 11 and 12 for layer 20i in Figure 19, while this direction D makes an angle of 67° with the edges 11 and 12 for layer 30i in Figure 20.

[0110] In the embodiment of the invention, as shown by way of example in Figure 21, a lower fillet 161i, 162i may be present under the part connecting the bridge 213, 313, 313i to the edge 11. Another lower fillet 162i may be present under the part connecting the bridge 213, 313, 313i to the edge 12.

[0111] According to one embodiment of the invention, as illustrated by way of example in Figure 18, the edges 11 and 12 can form a rectangular or square frame, parallel to the X and Y directions. The edge 11 can have a side 1la parallel to the X direction and an adjacent side 11b, which is parallel to the Y direction and connected to side 1la and side 12a. The edge 12 can have a side 12a parallel to the X direction and an adjacent side 12b, which is parallel to the Y direction and connected to side 12a and side 1ia. The displacements D forming the bridges 213, 313, 313i and can be oblique at an angle greater than 0° and less than 90° (for example 45° in figure 18) with respect to the X and Y directions to join side 11a to side 12b and to join side 11b to side 12a.Of course, the embodiments, characteristics, possibilities and examples described above can be combined with each other or selected independently of each other.

Claims

DEMANDS 1. A method for manufacturing a part (P) by a powder bed fusion additive manufacturing machine (1000), characterized in that the method comprises the following steps: performing a prescribed number of iterations (i) to form an undercut outer surface (31) of the part (P), the prescribed number (N) of iterations (i) being greater than or equal to 2, each iteration (i) comprising: the deposition (E2), by the machine (1000), of a subsequent layer (30, 30i) of powder onto an underlying layer (20, 20i) of powder; the scanning (E3), by a heating beam emitted by the machine (1000), of at least one subsequent zone (310, 31i) of powder, which is located within the subsequent layer (30, 3i) of powder and which includes a first anchor edge (11) and a second anchor edge (12) located in with respect to the first edge (11) anchorage, and a bridge (213, 313, 313i), which connects the first anchorage edge (11) to the second edge (12) anchor and which is located on a volume (215, 215i) of unfused powder from the underlying layer (20, 20i) of powder, to effect the fusion of the next zone (310, 310i) of powder into the next layer (30i) of powder, the cooling (E4), for a non-zero prescribed time (T), of the next zone (310, 310i) of powder having been fused, the first anchor edge (11), which has been fused into the layers (20, 30, 20i, 310i), extending along at least one vertical component (z), the second anchor edge (12), which has been fused into the layers (20, 30, 20i, 30i), extending along at least the vertical component (z), the bridges (213, 313, 313i) being fused to one another the other in layers (20, 30, 20i, 30i), the bridges (213, 313, 313i) being undercut relative to each other and forming the undercut outer surface (31),at least a lower part (110) of the first anchor edge (11) and at least a lower part (120) of the second anchor edge (12) being subsequently removed (E5).

2. Method according to claim 1, characterized in that the first anchoring edge (11) has a first prescribed horizontal length (L1), the second anchoring edge (12) has a second prescribed horizontal length (L2, x) located opposite the first prescribed horizontal length.

3. A method according to claim 2, characterized in that the method comprises, before the prescribed number of iterations (i), the formation (E1) by the machine (1000), by depositing several lower layers (10) of powder, portions (110, 120) of which are fused and then successively cooled one on top of the other, of a lower portion (110) of the first anchor edge (11) and a lower portion (120) of the second anchor edge (12), a lower volume (15) of unfused powder extending between the lower portion (110) of the first anchor edge (11) and the lower portion (120) of the second anchor edge (12) along the first prescribed horizontal length (L1) and along the second prescribed horizontal length (L2, x), the lower portion (110) of the first anchor edge (11) and the lower portion (120) of the second anchor edge (12) being removed (E5) after the prescribed number of iterations (i).

4. A method according to claim 3, characterized in that the prescribed number of iterations (i) comprises a first iteration (i=l) comprising: the deposition (E2), by the machine (1000), as the next layer (30) of powder, of a first upper layer (20) of powder on the lower part (110) of the first anchoring edge (11), on the lower part (120) of the second anchoring edge (12), and on the lower volume (15) of unfused powder located between them as an underlying layer (20) of powder; the sweeping (E3), by the heating beam emitted by the machine (1000), as the next zone (310) of powder, of at least a first zone (210) of powder, which is located in the first upper layer (20) of powder and which comprises a first initial part (211) covering, along the first prescribed horizontal length (Ll), the lower part (110) of the first edge (11) anchoring, a second initial part (212),covering along the second prescribed horizontal length (L2, x) the lower part (120) of the second anchor edge (12), and as a bridge an initial bridge (213) connecting the first initial part (211) to the second initial part (212), the initial bridge (213) being located on the lower volume (15) of unfused powder and having a length (Lx) smaller than the first prescribed horizontal length (L1) and the second prescribed horizontal length (L2, x) along the first anchor edge (11) and along the second anchor edge (12), the sweep (E3) effecting the fusion of the first zone (210) of powder into the first upper layer (20) of powder, the cooling (E4), for the non-zero prescribed time (T), of the first zone (210) of powder having been fused.

5. A method according to claim 4, characterized in that the subsequent zone (31 Oi) of powder having been fused during each iteration (i) subsequent to the first iteration (i=l) comprises: a first subsequent part (311, 31 li), which covers along the first prescribed horizontal length (Ll) a first underlying part (211, 21 li), a second subsequent part (312, 312i), which covers along the second prescribed horizontal length (L2) a second underlying part (212, 212i), and as a bridge a subsequent bridge (313, 313i) connecting the first subsequent part (311, 31 li) to the second subsequent part (312, 312i), the subsequent bridge (313, 313i) being located on a volume (215, 215i) of unfused powder of the underlying layer (20, 20i) of powder, a subsequent third part (314, 314i) located on a third underlying part (213, 213i) of the underlying layer (20i) of powder, the underlying layer (20, 20i) of powder being initialized to the first top layer (20) of powder, the first underlying part (211, 21li) being initialized to the first initial part (211), the second underlying part (212, 212i) being initialized to the second initial part (212), the third underlying part (213, 213i) being initialized to the initial bridge (213).

6. A method according to any one of the preceding claims, characterized in that the scanning (E3) is performed by individual displacements of the heating beam, which is a laser beam, each individual displacement being carried out at a prescribed speed VL of laser beam movement in the layer along a prescribed distance Lv from the first anchor edge (11) to the second anchor edge (12) along a second horizontal direction (Y), the laser beam having a prescribed width Ev along a first horizontal direction (X) perpendicular to the second horizontal direction (Y), so as to obtain an operating range, which is delimited in the IP plane e PL L V 'V F by a polygon, formed by successive vertices having the following coordinates Mi (2; 35), M2(15; 35), M3(30°, 180), M4 (25; 180), M5(10; 90) and M6(2; 90), where PL is a prescribed power of the laser beam, Ep is the prescribed thickness of each layer, Vs is a prescribed speed of advance of the laser beam from an individual displacement to an individual displacement along a prescribed direction (SI) of advance along the first horizontal direction (X) in each subsequent layer (30, 30i), a is a prescribed thermal diffusivity of the powder, the parameter E P L L y being expressed in J / mm, the number of Péclet being dimensionless.

7. A method according to any one of the preceding claims, characterized in that the part (P) is a turbomachine blade.

8. Computer program, comprising code instructions to control the steps of the manufacturing process of a part (P) by a powder bed fusion additive manufacturing machine (1000) according to any one of the preceding claims, when implemented on a computer (1001) of the machine (1000).

9. A machine (1000) for manufacturing a part (P) by powder bed fusion, characterized in that the machine (1000) comprises means for performing the following steps: executing a prescribed number of iterations (i) to form an undercut outer surface (31, 313) of the part (P), the prescribed number (N) of iterations (i) being greater than or equal to 2, each iteration (i) comprising: the deposition (E2), by the machine (1000), of a subsequent layer (30) of powder onto an underlying layer (20) of powder; the scanning (E3), by a heating beam emitted by an emitter of the machine (1000), of at least one subsequent zone (310) of powder, which is located in the subsequent layer (30) of powder and which comprises a first anchoring edge (11) and a second anchoring edge (12) located opposite the first anchoring edge (11), and a bridge (313), which connects the first anchoring edge (11) to the second anchoring edge (12) and which is located on a volume (215) of unfused powder from the underlying layer (20) of powder, to effect the fusion of the subsequent zone (310) of powder into the subsequent layer (30) of powder; the cooling (E4), for a non-zero prescribed time (T), of the subsequent zone (310) of powder having been fused, the first anchoring edge (11), which has been fused into the layers (20, 30), extending along at least one vertical component (z),the second anchor edge (12), which has been fused into layers (20, 30), extending along at least the vertical component (z), the bridges (313) being fused to each other in layers (20, 30), the bridges (313) being undercut relative to each other and forming the undercut outer surface (31, 313).

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