Additive manufacturing machine for producing annular parts

Abstract

The present invention relates to an additive manufacturing machine (10) for additive manufacturing by deposition of powder layers and selective solidification of these powder layers, the machine (10) comprising an apparatus (18) for depositing powder layers, a working surface (12), a selective solidification zone (14), a main jacket (42) of an outer contour (Cex), and a secondary jacket (46) arranged inside the main jacket (42) and defining a non-production zone (48) inside the selective solidification zone, the apparatus (18) for depositing powder layers comprising a powder distribution device (22) and a powder sprinkling device (24), the secondary jacket (42) being closed at the top by a flat closure wall parallel to the working surface (12) of the machine, the powder sprinkling device (24) moving in translation above the selective solidification zone (14) along a linear movement axis (DR).

Description

[Technical Field]

[0001] The present invention relates to an additive manufacturing machine by deposition of powder layers and selective solidification of these powder layers.

[0002] More specifically, the present invention is aimed at additive manufacturing by deposition of powder layers and selective solidification of large parts with a hollow central portion, such as stationary parts of turbojet engines, such as housings, stators, or rotating parts of turbojet engines, such as turbine disks.

[0003] When producing parts with hollow centers in an additive manufacturing machine with a cylindrical or parallelepiped production jacket, there is a large central volume within the production jacket where no part of the part is solidified, and as a result, this central volume is unnecessarily filled with powder.

[0004] To overcome this drawback, additive manufacturing machines have been designed with an annular production jacket. Thanks to the annular shape of the production jacket, these machines can produce large parts with hollow centers while limiting powder consumption.

[0005] Conventional Technology EP 3300819 relates to a machine for manufacturing annular parts by selective powder fusion, the machine comprising concentric inner and outer annular walls defining an annular powder deposition zone. To spread the powder layer, the machine comprises a powder distributor rotatable about the axis of the inner and outer annular walls, the powder distributor comprising a scraper extending between the inner and outer annular walls at an angle relative to the radial direction of the inner and outer annular walls. Due to the angle formed by the scraper relative to the radial direction, excess powder is expelled laterally towards the inside or outside of the annular zone.

[0006] The first drawback is that the rotary powder distributor described in EP 3300819 has relatively complex kinematics, requiring extensive testing before it can be validated for use in a manufacturing cycle. For example, due to its rotational motion, the scraper's speed is not uniform at every point along its length; it is minimum at its inner end and maximum at its outer end. Furthermore, different additive manufacturing powders have different flow characteristics. Therefore, for each type of powder, the best compromise must be found between the maximum speed at the outer end of the scraper and the minimum speed at the inner end of the scraper. Furthermore, the scraper's angle relative to the radial direction must be adjusted with each powder change. Summary of the Invention

[0007] The aim of the present invention is to improve these drawbacks of the prior art by proposing a configuration of an additive manufacturing machine that makes it possible to limit powder consumption when manufacturing parts with a hollow central section and that can be operated easily and quickly.

[0008] To this end, an object of the present invention is a machine for additive manufacturing by deposition of powder layers and selective solidification of these powder layers, the machine comprising a device for depositing powder layers and a source for selective solidification of the powder layers, the machine comprising a working surface and a selective solidification zone of the powder layer located on said working surface, the machine comprising a main jacket opening onto the working surface through an opening defining the outer contour of the selective solidification zone, the machine comprising a secondary jacket arranged inside the main jacket and defining a non-production zone inside the selective solidification zone, the machine comprising a build tray moving in translation between the main jacket and the secondary jacket under the influence of an actuator, and the powder layer deposition device comprising, above the selective solidification zone, a powder distribution device and a powder sprinkling device such as a roller or a scraper.

[0009] According to the invention, the secondary jacket is closed at the top by a flat closing wall parallel to the machine working surface, and the powder sprinkling device translates above the selective solidification zone along a linear movement axis.

[0010] Advantageously, but not necessarily, the present invention may also provide: the powder sprinkling device extends in a transverse direction perpendicular to its linear motion axis, the length of the powder sprinkling device in the transverse direction is greater than the maximum dimension of the outer contour of the selective solidification zone in this transverse direction; when the powder sprinkling device is in a standby position outside the selective solidification zone, the powder distribution device allows for supplying or depositing a powder bead onto a working surface between the selective solidification zone and the powder sprinkling device; the powder dispensing device comprises a powder receiving surface movable relative to the work surface and the selective solidification zone; the powder dispensing device comprises a powder reservoir movable above the work surface; - the upper surface of the secondary jacket closure wall is in the same plane as the upper surface of the working surface, the build tray comprises a closed contour opening through which the secondary jacket passes; - the secondary jacket is identical in shape to the main jacket in the horizontal plane, but is scaled down similarly; the secondary jacket and the main jacket are cylindrical and extend vertically; The secondary jacket and the main jacket are coaxial. [Brief explanation of the drawings]

[0011] Further features and advantages of the invention will become apparent in the following description, given by way of example and not limitation, with reference to the accompanying drawings, in which: [Figure 1] 1 is a schematic top view of a machine according to the invention with a first variant of the powder distribution device; FIG. [Figure 2] 1 is a schematic side view of a machine according to the invention with a second variant of the powder distribution device; DETAILED DESCRIPTION OF THE INVENTION

[0012] The present invention relates to an additive manufacturing machine by deposition of powder layers and selective solidification of these powder layers.

[0013] Additive manufacturing by powder layer deposition and selective solidification is an additive manufacturing method in which one or more parts are produced by selectively solidifying different layers of additive manufacturing powder that are superimposed on one another. A first layer of powder is deposited on a support, such as a tray, and then selectively solidified using at least one solidification source along a first section of the one or more parts to be produced. A second powder layer is then deposited on the just-solidified first powder layer, and this second powder layer is selectively solidified in that order, continuing in this manner until the last powder layer useful for producing the final section of the one or more parts to be produced.

[0014] In the context of the present invention, additively manufactured powders are preferably metallic, but may also be non-metallic.

[0015] A powder bed deposition and selective solidification additive manufacturing machine 10 according to the present invention is shown schematically in a top view by FIG.

[0016] The machine 10 includes a work surface 12 and a powder layer selective solidification zone 14 located on the work surface. The work surface 12 and selective solidification zone 14 are preferably located within an enclosure 16 that may be sealably closed. One wall of the enclosure 16 may include a door that provides access to the work surface 12 and selective solidification zone 14. The work surface 12 and selective solidification zone 14 are preferably in a horizontal plane.

[0017] To implement additive manufacturing, the machine 10 comprises a powder layer deposition device 18 and at least one source 20 for selective solidification of the powder layer.

[0018] In the example shown in Figure 2, the machine 10 comprises several selective solidification sources 20. This plurality of selective solidification sources is suitable for the additive manufacturing of large parts in large selective solidification zones 14. Indeed, the machine according to the invention is particularly intended for the manufacturing of large parts and preferably provides large selective solidification areas 14. Large parts are, for example, parts having an outer diameter greater than 35 centimeters and a height greater than 35 centimeters.

[0019] Preferably, each selective solidification source 20 is a source that emits at least one laser beam for melting at least a portion of the powder layer present in the solidification zone 14. The laser source 20 includes, for example, a scanning head for moving a laser beam spot over at least a portion of the selective solidification zone 14 and a device for managing the laser beam focus. Each source 20 may also include a device for monitoring the emitted laser beam and / or a molten bath created by the emitted laser beam in the powder layer.

[0020] Alternatively, the selective solidification source may be a particle beam, such as an electron gun.

[0021] The apparatus 18 for depositing the powder layer comprises, above the selective solidification zone 14, a powder distribution device 22 and a powder sprinkling device 24, such as a roller or scraper.

[0022] Preferably, the powder distribution device 22 is used to supply or deposit a powder bead onto the work surface 12 between the selective solidification zone 14 and the powder distribution device 24 when the powder distribution device 24 is in a standby position outside the selective solidification zone, for example as shown in FIG. 1.

[0023] In a first variant, the powder distribution device 22 comprises at least one powder distributor 25 and a powder receiving surface 26 that is movable relative to the work surface 12 and the selective solidification zone 14 and relative to the powder distributor 25. For example, the powder distributor 25 comprises a powder reservoir mounted above a screw feeder. The movable receiving surface 26 moves below the powder distributor 25 to receive the powder delivered by the distributor 25 and form a bead of powder on the movable receiving surface. The receiving surface 26, together with the powder bead, is then positioned between the spreading device 24 and the selective solidification zone 14, so that the spreading device 24 can spread the powder bead on the selective solidification zone.

[0024] 1, the powder distribution device 22 comprises two distributors 25 located on either side of the selective solidification zone 14 and two movable powder receiving surfaces 26 located on either side of the selective solidification zone 14. In this way, the powder sprinkling device 24 can spread a new layer of powder during each of its movements over the selective solidification zone.

[0025] In a second variant, the powder dispensing device 22 comprises at least one powder reservoir 28 that is movable above the work surface 12. For example, the movable powder reservoir 28 is attached to the powder sprinkling device 24. Preferably, the powder reservoir 28 is also mounted for translational movement relative to the sprinkling device 24 in order to deposit a bead of powder in front of the sprinkling device. The powder dispensing device 22 preferably comprises a powder inlet 30 in the enclosure 16 for refilling the movable powder reservoir 28 with powder.

[0026] 2, the powder distribution device 22 includes two movable powder reservoirs 28 attached to the distribution device, one on each side of the distribution device. In this way, a bead of powder can be deposited on each side of the distribution device, and the powder distribution device 24 can distribute a new layer of powder during each of its movements over the selective solidification zone 14.

[0027] In a first variant of the powder distributor 22, each movable powder receiving surface 26 is translationally mounted within a housing 32 provided on the work surface. Advantageously, this housing 32 allows excess powder to be collected when a new layer of powder is applied to the selective solidification zone.

[0028] In a second variation of the powder dispensing device 22, at least one reservoir 34 for collecting excess powder is provided on the work surface 12. Preferably, two reservoirs 34 for collecting excess powder are provided, one on each side of the selective solidification zone 14.

[0029] Due to the fumes generated by the selective powder melting operation in the solidification zone, the machine 10 preferably includes a device 36 for collecting the fumes generated by the selective solidification. This collection device 36 makes it possible to generate a flow of exhaust gas F above the selective solidification zone. More specifically, the exhaust gas flow F circulates, for example, between an inlet ramp 38 located on one side of the solidification area 14 and an outlet ramp 40 located on the other side of the solidification area 14. For example, the collection device 36 may include a device for generating the exhaust gas flow F and a fume filtering device (not shown) located in a circuit connected to the inlet and outlet ramps.

[0030] Advantageously, the inlet 38 and outlet ramp 40 can be translated between a position dedicated to selective melting (shown in dotted lines in FIG. 1 ) and a position dedicated to powder layer formation (shown in solid lines in FIG. 1 ), where in the position dedicated to selective melting the inlet ramp 38 and outlet ramp 40 are located as close as possible to the selective solidification zone, and in the position dedicated to powder layer formation the inlet ramp 38 and outlet ramp 40 are further away from the selective solidification zone so as not to interfere with the movement of the powder application device.

[0031] Selective Solidification Zone According to the invention, in particular for producing large parts with a hollow central portion, the machine 10 comprises a main jacket 42 opening onto the work surface 12 through an opening 44 defining the outer contour Cex of the selective solidification zone 14, at least one secondary jacket 46 arranged inside the main jacket 42 and defining a non-production zone 48 inside the selective solidification zone 14, and a build tray 50 translatably moving between the main jacket 42 and the secondary jacket 46 under the influence of at least one actuator 52. The non-production zone 48 is a sub-zone of the selective solidification zone 14 in which selective powder solidification does not take place.

[0032] In a selective solidification zone variation not shown, the machine 10 may include several secondary jackets 46 disposed within the main jacket 42 and defining several non-production zones 48 within the selective solidification zone 14. In this case, the build tray 50 translates between the main jacket 42 and the various secondary jackets 46.

[0033] More specifically, the primary jacket 42 extends below the work surface 12. For example, the primary jacket 42 is removably attached to the work surface 12. Each secondary jacket 46 also extends below the work surface 12. For example, each secondary jacket 46 is removably attached to a support 54 integral with the frame of the machine 10. The primary jacket 42 and secondary jackets 46 are removably attached to facilitate removal from the machine along with fabricated parts and build trays 50, for example, through the underside of the machine.

[0034] The build tray 50 preferably translates along a vertical axis AV, which corresponds to the vertical direction in which the various layers of powder are superimposed. Preferably, several actuators 52 are used to move the build tray 50 relative to the primary and secondary jackets. Advantageously, in addition to the actuators, the machine 10 can include means (not shown) for guiding the build tray in translation.

[0035] According to the invention, in order to limit powder consumption when manufacturing large parts with hollow central portions, each secondary jacket 46 is closed at the top by a flat closing wall 56 parallel to the working surface 12 of the machine.

[0036] In addition to the closure at the top of each secondary jacket, the powder sprinkler 24 translates above the selective solidification zone 14 along the linear movement axis DR. In combination with the closure at the top of each secondary jacket, the linear movement of the sprinkler 24 quickly and easily controls the layering of powder on the selective solidification zone. In fact, thanks to the linear movement of the sprinkler, the speed of the rollers or scrapers of the sprinkler is the same over its entire length, and thanks to the closure at the top of each secondary jacket, powder layering occurs as if the selective solidification zone 14 did not include a non-production zone.

[0037] Preferably, the linear movement axis DR of the powder sprinkler 24 is horizontal. Preferably, the linear movement axis DR of the powder sprinkler 24 is perpendicular to the fume exhaust gas flow F. Preferably, the linear movement axis DR of the powder sprinkler 24 is perpendicular to the vertical axis of translation AV of the build tray 50.

[0038] Spraying equipment To easily and quickly control the formation of the powder layer on the selective solidification zone 14, the powder spreading device 24 extends in a transverse direction DT perpendicular to its linear movement axis DR. More precisely, the rollers or scrapers of the powder spreading device 24 extend in a transverse direction DT perpendicular to its linear movement axis DR.

[0039] To ensure that the powder layer formation is of uniform thickness over the entire surface of the selective solidification zone 14, the length L24 of the powder spreader 24 in the transverse direction DT is greater than the maximum dimension DM of the outer contour Cex of the selective solidification zone 14 in this transverse direction DT. Preferably, to avoid moving the entrance ramp 38 and the exit ramp 40 too far from the solidification zone 14, the length L24 of the powder spreader 24 in the transverse direction DT is only a few millimeters greater than the maximum dimension DM of the outer contour Cex of the selective solidification zone 14 in this transverse direction DT.

[0040] The powder spreading device 24 extends in a transverse direction DT over a length L24 that is greater than the maximum dimension DM of the outer contour Cex of the selective solidification zone 14 and moves along a linear movement axis DR, thereby providing an easy-to-implement powder layer formation and a higher deposition rate than rotary powder distribution solutions.

[0041] Jacket and tray In a first preferred variant of the closure at the top of each secondary jacket, the upper surface 58 of the closure wall 56 of the secondary jacket 46 is in the same plane as the upper surface 60 of the working surface 12. In this first variant, the upper surface 58 of the closure wall 56 of the secondary jacket 46 and the upper surface 60 of the working surface 12 are a few tenths of a millimeter, for example 0.5 millimeters, below the generatrix of the rollers or scrapers of the spreading device 24. This prevents the rollers or scrapers from rubbing against the upper surface 58 of the closure wall 56 of the secondary jacket 46 and the upper surface 60 of the working surface 12. This space between the generatrix of the rollers or scrapers of the spreading device 24 and the upper surfaces of the closure wall 56 and the working surface 12 is filled with powder during the formation of the first powder layer and remains filled with powder until the end of production.

[0042] In a second variant (not shown), the upper surface 58 of the closure wall 56 of the secondary jacket 46 is very slightly, for example by a few tenths of a millimeter, above the plane of the upper surface 60 of the working surface 12. In this second variant, the upper surface 58 of the closure wall 56 of the secondary jacket 46 is always located below the generatrices of the rollers or scrapers of the spraying device 24.

[0043] In a third variant (not shown), the upper surface 58 of the closure wall 56 of the secondary jacket 46 is located very slightly, for example, by a few tenths of a millimeter, below the plane of the upper surface 60 of the work surface 12. In this third variant, a significant powder thickness of a few tenths of a millimeter must be formed above the closure wall 56 by the spreader 24. This significant powder thickness is achieved at the beginning of the production cycle during the formation of the first powder layer by using the distributor 22 to distribute more powder before the spreader 24 than for the formation of the next powder layer. Advantageously, the first layer of powder solidified in the selective solidification zone 14 is produced simultaneously with this significant powder thickness.

[0044] Ideally, the secondary jacket 46 is completely surrounded by the build tray 50. The build tray 50 also includes a closed contour opening 62CF through which the secondary jacket 46 passes. If several secondary jackets 46 are placed inside the main jacket 42, the build tray 50 will include several openings 62 with a closed contour CF, each of which will be passed by one of the secondary jackets 46.

[0045] In the illustrated example, the secondary jacket 46 has the same shape in the horizontal plane as the main jacket 42, but is scaled accordingly. For example, the main jacket 42 has a circular outer contour Cex, and the inner contour CI of the secondary jacket 46 is also circular, but has a diameter 1.01 to 10 times smaller, and the inner contour CI of the secondary jacket 46 corresponds to the closed contour CF of the opening 62 provided in the tray 50 for this secondary jacket. However, the main jacket 42 and the secondary jacket 46 can have different shapes, for example polygonal.

[0046] To produce annular parts, i.e., parts with an axis of rotation, the secondary jacket 42 and the main jacket 46 are, for example, cylindrical and extend in a vertical direction DV parallel to the vertical axis AV of translation of the tray 50 and superposition of the powder layers. For example, the secondary jacket 46 and the main jacket 42 are coaxial about the same vertical central axis ACV.

[0047] In the present invention, the primary jacket 42 and secondary jacket 46 take the form of metal walls several millimeters thick, at least 15-20 millimeters thick.

[0048] Advantageously, sealing means 64 such as gaskets may be provided between the build tray 50 and the primary and secondary jackets 42, 46 to prevent leakage of powder towards the bottom of the machine 10.

[0049] Transform Alternatively (not shown), the inlet ramp 38 and the outlet ramp 40 of the fume collector 36 may be positioned along the outer contour Cex of the selective solidification zone 14 and the inner contour C1 of the secondary jacket 46. In a first example, the inlet ramp 38 is positioned along the outer contour Cex of the selective solidification zone 14, and the outlet ramp 40 is positioned along the inner contour C1 of the secondary jacket 46. In another example, the inlet ramp 38 is positioned along the inner contour C1 of the secondary jacket 46, and the outlet ramp 40 is positioned along the outer contour Cex of the selective solidification zone 14. In such a configuration, if the selective solidification zone 14 is annular, the fume exhaust gas flow F extends radially above the selective solidification zone 14. Furthermore, in this configuration, the inlet 38 and outlet 40 ramps may be recessed into the work surface 12 or elevated several centimeters above the work surface 12, for example, so as not to interfere with the movement of the powder application device.

Claims

1. A machine (10) for additive manufacturing by deposition of powder layers and selective solidification of these powder layers, the machine (10) comprising an apparatus (18) for depositing powder layers and a source (20) for selectively solidifying the powder layers, the machine comprising a work surface (12) and a selective solidification zone (14) for the powder layer located on the work surface, the machine comprising a primary jacket (42) opening onto the work surface through an opening (44) defining an outer contour (Cex) of the selective solidification zone, the machine comprising a secondary jacket (42) arranged inside the primary jacket (42) and defining a non-production zone (48) inside the selective solidification zone. a powder layer deposition device (18) for depositing powder from a powder bed (46) in a selective solidification zone (14) along a linear axis of movement (DR), the powder layer deposition device (18) comprising a powder distributor (22) and a powder spreader (24), such as a roller or a scraper, above the selective solidification zone (14), the powder layer deposition device (18) being closed at the top by a flat closure wall (56) parallel to the machine working surface (12), and the powder spreader (24) being moved in translation above the selective solidification zone (14) along a linear axis of movement (DR).

2. 2. The additive manufacturing machine of claim 1, wherein the powder spreading device (24) extends in a transverse direction (DT) perpendicular to its linear movement axis (DR).

3. 3. The additive manufacturing machine of claim 2, wherein a length (L24) of the powder sprinkling device (24) in the transverse direction (DT) is greater than the maximum dimension (DM) of the outer contour (Cex) of the selective solidification zone (14) in said transverse direction (DT).

4. 4. The additive manufacturing machine of claim 1, wherein the powder distribution device (22) is capable of supplying or depositing a powder bead onto the work surface (12) between the selective solidification zone (14) and the powder sprinkling device (24) when the powder sprinkling device (24) is in a standby position outside the selective solidification zone (14).

5. 5. The additive manufacturing machine of claim 4, wherein the powder dispensing device (22) comprises a powder receiving surface (26) movable relative to the work surface (12) and the selective solidification zone (14).

6. The additive manufacturing machine of claim 4, wherein the powder dispensing device (22) comprises a powder reservoir (28) movable above the work surface.

7. The additive manufacturing machine of any one of claims 1 to 6, wherein an upper surface (58) of the closure wall (56) of the secondary jacket is in the same plane as an upper surface (60) of the work surface (12).

8. The additive manufacturing machine of any one of claims 1 to 7, wherein the build tray (50) comprises an opening (62) having a closed contour (CF) through which the secondary jacket (46) passes.

9. 9. The additive manufacturing machine of claim 8, wherein the secondary jacket (46) is identical in shape to the main jacket (42) in a horizontal plane, but is scaled similarly.

10. 10. The additive manufacturing machine of claim 9, wherein the secondary jacket (46) and the main jacket (42) are cylindrical and extend in a vertical direction (DV).

11. The additive manufacturing machine of claim 10, wherein the secondary jacket (46) and the main jacket (42) are coaxial.

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