Three-dimensional part additive manufacturing facility

Abstract

The invention relates to a manufacturing installation (10) for a metal part. It comprises: a cylindrical enclosure (12) and a platform (18) movable inside said enclosure (12); a storage tank (36) for a powdered metallic material; a transfer device (28) movable for being able to superimpose a plurality of layers (54) of said metallic material on said platform (18) as said platform is lowered; a printing device (62) for printing a binder (60) on the surface of each of the layers. Said transfer device comprises a transfer table (24), and a transfer cylinder (28) erected on said transfer table; and said transfer cylinder (28) is adapted to receive said powdered metallic material and to be driven from the transfer table (24) to said cylindrical enclosure (12) to superimpose the layers of said metallic material. Figure to be published with the abstract: Fig. 1

Description

Title of the invention: Installation for the additive manufacturing of three-dimensional parts

[0001] The present invention relates to an installation for the additive manufacturing of three-dimensional metal parts.

[0002] Known additive manufacturing installations make it possible to use a powdered metallic material and to preform the parts in this powdered metallic material, by binding the particles of the material together. The particles are then hot sintered to consolidate the parts.

[0003] Also, such installations comprise a device for stratifying the powdery material to superimpose on a mobile platform in a vertical direction, a plurality of layers of particles of said material. The layers are deposited successively on top of each other and a binder is printed according to predefined patterns on each of them so as to be able to locally bind the particles of the material of the layer together and also the particles located at the interface with the underlying layer.

[0004] In this way, over the layers, the part is drawn in three dimensions, made of particles of the metallic material bonded together. The part thus obtained, called a "green part", is then freed from the unbonded particles surrounding it, to be brought to a high temperature. The bonded metallic particles then weld together and the final part is obtained.

[0005] However, the dimensional deviations of a series of the same parts, for example, can be relatively significant, and they depend in particular on the compactness and homogeneity of the layers of the powdered material.

[0006] Layering installations usually proceed by spreading a bed of powder using a scraper or rollers.

[0007] Document US 2020 038958 shows for example a two-roller laminating device, an upstream roller for forming the layer of powdered material from a reservoir of said material, and a downstream roller for compacting said layer.

[0008] However, when the powdered material comprises particles with a small particle size of less than 100 μm, or less than 30 μm for example, the layers are heterogeneous. And this heterogeneity is detrimental to the dimensional stability of the parts.

[0009] Also, a problem which arises and which the present invention aims to solve is to provide an installation for additive manufacturing of metal parts making it possible to reduce the dimensional variability of the parts obtained.

[0010] In order to solve this problem and according to a first object, there is proposed an installation for additive manufacturing of a three-dimensional metal part comprising: a cylindrical enclosure adapted to be oriented vertically and a platform mounted to move in translation inside said enclosure; a storage tank for a powdered metallic material located in the vicinity of said cylindrical enclosure; a transfer device mounted to move horizontally in translation relative to said cylindrical enclosure to be able to sequentially transfer a plurality of given quantities of said metallic material, from said tank to said enclosure, and to superimpose a plurality of layers of said metallic material on said platform as said platform is lowered into said cylindrical enclosure; a bonding device for bonding said powdered metallic material of each of the layers according to predefined patterns.

[0011] Said transfer device comprises a transfer table installed at the edge of said cylindrical enclosure, and a transfer cylinder erected on said transfer table; and said transfer cylinder is adapted to receive said powdered metallic material from said storage tank and to be driven in translation from the transfer table to said cylindrical enclosure to superimpose the layers of said metallic material.

[0012] Thus, a characteristic of the invention lies in the implementation of a transfer cylinder, or shoe, inside which the powdered metallic material is preconditioned to then be delivered in successive layers onto the platform.

[0013] The transfer cylinder is erected on the transfer table and is open at its lower end. The lower end of the cylinder has a lower edge closed on itself. And the lower edge is applied to the transfer table. In this way, the powdered metallic material is loaded inside the transfer cylinder in the form of a column, and it then already has a certain compactness. The joint between the lower edge and the transfer table is sealed against the powdered metallic material.

[0014] Also, the translational movement of the transfer cylinder on the transfer table does not in any way impair this sealing.

[0015] Furthermore, there is no discontinuity between the transfer table and the edge of the cylindrical enclosure, so that the translation of the column of powdered metallic material in friction on the table then on the edge of the enclosure does not cause any deterioration of the layer in contact.

[0016] When the transfer cylinder comes into a position where it is perfectly aligned with the cylindrical enclosure, the platform is lowered by one step, corresponding substantially to the thickness of a layer of powdered material that it is desired to deposit. Then, the transfer cylinder is driven in translation back onto the transfer table. And the leveling of the deposited layer is thus carried out via the edge of the transfer cylinder. This mechanism will be explained in more detail later in the description.

[0017] In this way, a more compact and more homogeneous layer is obtained. Consequently, a lower dimensional variability of the parts thus produced will subsequently be obtained.

[0018] According to an alternative in accordance with the invention, said binding device comprises a printing member for printing a binder according to said predefined patterns on the surface of each of the layers of said powdered metallic material.

[0019] According to another alternative, said bonding device comprises a laser member capable of scanning the surface of the layers of powdered metallic material by means of a laser beam to locally fuse, according to a predefined pattern, the particles of the powdered metallic material.

[0020] According to a particularly advantageous embodiment of the invention, said transfer cylinder has a cross section substantially identical to the cross section of said cylindrical enclosure. In this way, when the platform is lowered by one step, the entire column of powdered metallic material of the transfer cylinder is lowered. In this way, the homogeneity of the powdered material is maintained, in particular in the layer which will remain in contact with the previous layer.

[0021] Furthermore, the transfer cylinder may have several cylindrical compartments in order to be able to form contiguous layers of powdered metallic material of different nature.

[0022] Furthermore, it is also provided to implement at least two transfer cylinders adapted to be driven perpendicularly to one another in order to be able to alternately carry the two transfer cylinders in line with the cylindrical enclosure. Such an implementation also makes it possible to deposit layers of powdered metallic material of different natures.

[0023] According to the invention, said transfer cylinder preferably has two substantially parallel longitudinal edges of contact with said transfer table. These two parallel longitudinal edges of contact are oriented in the direction of movement of the transfer cylinder. Also, the cylindrical enclosure has two enclosure edges which are also parallel and extend in the extension of the two parallel contact edges. In this way, the two contact edges slide precisely on the two enclosure edges. The joint between the two contact edges and the two enclosure edges remains sealed against the powdered material.

[0024] In addition, the transfer cylinder also has two transverse edges, one of which has a leveling function as will be explained in more detail below. of the description.

[0025] According to the invention, said storage tank is advantageously installed in line with said transfer table. In this way, the transfer cylinder can be loaded with powdered metallic material by gravity when it is substantially directly above the storage tank.

[0026] According to the invention, and according to a first variant embodiment, the installation comprises a flexible conduit extending between said storage tank and said transfer cylinder. In this way, the transfer cylinder can be continuously supplied with powdered material, including in the phase where it extends in line with the cylindrical enclosure.

[0027] According to a second embodiment, the transfer cylinder is supplied with powdered material sequentially, only when it is on the transfer table. Also, a relatively sealed temporary connection is established between the storage tank and the transfer cylinder during the supply.

[0028] Preferably, according to the invention, said storage tank comprises a hopper equipped with a chute with controllable opening. The hopper facilitates gravity flow and the chute provided with the recommended opening easily allows the sequential filling of the transfer cylinder.

[0029] According to a particularly advantageous embodiment of the invention, the installation comprises a transducer mounted on said transfer cylinder. For example, the transducer is adapted to generate ultrasound. In this way, the powdery material is homogenized and pre-compacted inside the transfer cylinder.

[0030] Also, according to the invention, said platform is advantageously lowered into said cylindrical enclosure when said transfer cylinder comes in line with said cylindrical enclosure. It is lowered by a step corresponding substantially to the thickness of the desired layer.

[0031] Furthermore, according to a particularly advantageous embodiment of the invention, the installation comprises a leveling device mounted to move in translation on said cylindrical enclosure. The leveling device is implemented after the deposition of a layer of powdery material and the removal of the transfer cylinder. In this way, the compactness of the deposited layer is further improved.

[0032] According to a second object, a method for additive manufacturing of a three-dimensional metal part is proposed, comprising the following steps: a cylindrical enclosure is provided, adapted to be oriented vertically, and a platform mounted to move in translation inside said enclosure; a storage tank of a powdered metallic material is provided, located in the vicinity of said cylindrical enclosure; a plurality of given quantities of said metallic material are transferred sequentially in a horizontal direction, from said tank to said enclosure; superimposes a plurality of layers of said metallic material on said platform, while lowering said platform gradually into said cylindrical enclosure; bonding said powdered metallic material of each of the layers according to predefined patterns.

[0033] Also, a transfer table installed at the edge of said cylindrical enclosure is further provided, and a transfer cylinder erected on said transfer table, said transfer cylinder being adapted to receive said powdered metallic material from said storage tank; and said transfer cylinder is driven in translation from the transfer table to said cylindrical enclosure to superimpose the layers of said metallic material.

[0034] The additive manufacturing installation described above makes it possible to implement the aforementioned method with the advantages which result therefrom.

[0035] Preferably, a binder is printed according to said predefined patterns on the surface of each of the layers of said metallic material to bind said powdered metallic material.

[0036] According to another embodiment, said powdered metallic material of each of the layers is bonded according to predefined patterns, by means of a guided laser beam. In this way, thanks to the laser beam, the local melting of the particles of the powdered metallic material is caused and their aggregation is contributed to. The parts are then finished when the last layer of powdered material is deposited and there is then no need to place them in a furnace to sinter the particles.

[0037] Other features and advantages of the invention will emerge from reading the description given below of particular embodiments of the invention, given for informational but non-limiting purposes, with reference to the appended drawings in which:

[0038] [Fig.l] is a schematic side view of an installation according to the invention in a first state;

[0039] [Fig.2] is a schematic side view of an installation according to the invention in a second state;

[0040] [Fig.3] is a schematic side view of an installation according to the invention in a third state;

[0041] [Fig.4] is a schematic side view of an installation according to the invention in a fourth state;

[0042] [Fig.5] is a schematic side view of an installation according to the invention in a fifth state;

[0043] [Fig.6] is a schematic side view of an installation according to the invention in a sixth state; and,

[0044] [Fig.7] is a flowchart of the implementation method according to the invention.

[0045] [Fig.l] shows an additive manufacturing installation 10 according to the invention. and allowing the production of three-dimensional metal parts.

[0046] It comprises a cylindrical enclosure 12 having a rectangular cross section and an upstream wall 13 having an upstream edge 14 opposite a downstream wall 15 having a downstream edge 16. It also has a longitudinal wall having respectively two longitudinal edges of the enclosure not shown. Also, a platform 18 is slidably mounted inside the cylindrical enclosure 12. The platform 18 extends along a substantially horizontal mean plane and perpendicular to the generatrices of the cylindrical enclosure 12. The platform 18 is moved by a first actuator, an electric jack 20, which allows it to be driven in translation step by step as will be explained below. The platform 18 has an application face 22 extending, in [Fig.l], at the level of the upstream 14 and downstream 16 edges.

[0047] Also, the installation 10 comprises a leveling device 23 installed in the vicinity of the cylindrical enclosure 12 on the side of the downstream edge 16. The leveling device 23 comprises in particular a roller 25, the operation of which will be explained below.

[0048] Furthermore, the installation 10 comprises a transfer table 24 extended horizontally along the upstream edge 14 of the cylindrical enclosure 12. Also, the transfer table 24 has a width greater than or equal to the width of the cylindrical enclosure 12. In addition, it has a transfer face 26 located at the level of the upstream 14 and downstream 16 edges. This transfer face 26 has a surface condition whose roughness coefficient Ra is for example less than 1.6 μm and advantageously less than 0.8 μm. Such polishing is obtained by mechanical or electrolytic means.

[0049] The transfer table 24 has a length substantially greater than the length of the cylindrical enclosure 12 which extends from the upstream edge 14 to the downstream edge 16.

[0050] Also, a transfer cylinder 28 is erected on the transfer table 24. The transfer cylinder 28 has a rectangular cross section, and a front wall 29 having a front edge 30, opposite a rear wall 31 having a rear edge 32. The front edge 30 and the rear edge 32 are joined together by two longitudinal edges of the transfer cylinder 28 not shown. Thus, the rear edges 32 and front 30 as well as the longitudinal transfer edges define the same plane and they come into contact with the transfer face 26 of the transfer table 24.

[0051] Furthermore, the front 30, rear 32 and longitudinal edges of the cylinder 28 also have a roughness coefficient Ra advantageously less than 1.6 μm. Preferably, the upstream 14, downstream 16 and longitudinal edges of the enclosure have a comparable roughness coefficient Ra.

[0052] In addition, the longitudinal enclosure walls and the longitudinal transfer walls advantageously have a thickness greater than 1 cm. Therefore, the longitudinal enclosure edges and the longitudinal transfer edges have a width greater than 1 cm, and they are respectively spaced apart from each other by a distance neighbor. Advantageously, the longitudinal transfer walls are spaced apart by a distance substantially greater than the distance separating the longitudinal enclosure walls. Consequently, the longitudinal transfer edges and the enclosure edges are spaced apart by a corresponding distance. The advantage of such a configuration will be explained in the rest of the description.

[0053] Also, the transfer cylinder 28 is equipped with a first transducer 34, represented by superimposed triangular wave portions whose function will be explained below. The first transducer 34 is capable of delivering ultrasonic waves.

[0054] Furthermore, the installation comprises a storage hopper 36 inside which a powdered metallic material is stored. For example, the powdered metallic material used has particles with an average size of between 10 μm and 30 μm. Thanks to this relatively low average particle size, the sintering of the part obtained by means of the installation 10 can be carried out at a lower temperature.

[0055] The storage hopper 36 has a chute 38 and a closing hatch 40 allowing the opening of the chute 38 to be freed or closed. In addition, a screen is advantageously installed across the chute 38 to be able to filter any aggregates contained in the hopper 36.

[0056] Also, the storage hopper 36 is also equipped with a second transducer 42 capable of delivering ultrasonic waves. It is preferably installed on the chute 38.

[0057] Furthermore, the installation comprises a second actuator 44, a second electric jack for example, connected to the transfer cylinder 28 in order to be able to drive it in translation towards the cylindrical enclosure 12 as will be explained below with reference to [Fig.2] to [Fig.6] and to [Fig.7].

[0058] Thus, in a first step 46 illustrated in [Fig.7] and where all the elements described above are in a relative position as illustrated in [Fig.l], and in particular where the platform 18 is located at the same level as the transfer table 24, the transfer cylinder 28 is filled by releasing the chute 38 by means of the closing hatch 40. Thus, the powdered metallic material from the storage hopper 36 pours into the transfer cylinder 28. Furthermore, the first and second transducers 34, 42 are supplied. In this way, the flow of the powdered material through the chute 38 is facilitated and, in addition, its compactness inside the cylinder 28 is increased. In other words, the density of the powdered material inside the cylinder 28 is increased. In this way, a column of powdered metallic material is obtained. 47 with a density close to the maximum possible density.

[0059] When the transfer cylinder 28 is sufficiently filled, the trapdoor is operated closing 40 of the chute 38 to close the latter. Then, following a second step 48, the second actuator 44 is controlled so as to cause the translational movement of the transfer cylinder 28 towards the cylindrical enclosure 12 until the transfer cylinder 28 extends perfectly in line with the enclosure 12.

[0060] Thus, during this translational movement, the transfer cylinder 28 is driven in sliding on the transfer face 26 of the transfer table 24, following the direction of the longitudinal transfer edges. Also, the column of powdered metallic material retains its structure locally, including at the level of the transfer face 26, the upstream edge 14 and the application face 22 of the platform 18.

[0061] It will be observed that the longitudinal transfer edges of the transfer cylinder 28 also come into sliding contact respectively against the longitudinal edges of the enclosure.

[0062] Thus, in [Fig.2], we find the transfer cylinder 28 at right angles to the cylindrical enclosure 12. In addition to the longitudinal edges of the enclosure and transfer bearing against each other, the front edge 30 of the transfer cylinder 28 bears on the downstream edge 16 of the enclosure 12, and the rear edge 32 bears on the upstream edge 14.

[0063] In [Fig.2], the front 30 and rear 32 edges coincide perfectly with the downstream 16 and upstream 14 edges. However, and advantageously, the front 29 and rear 31 walls of the transfer cylinder 28 are spaced from each other by a distance substantially greater than that which separates the upstream 13 and downstream 15 walls of the cylindrical enclosure 12.

[0064] According to a third step 50, identified in [Fig.7], the first actuator 20 is controlled to cause the lowering of the platform 18 by a predetermined step p, preferably less than 300 pm, as illustrated in [Fig.3]. For example, the platform 18 is lowered by a step between 30 pm and 100 pm.

[0065] Therefore, the column of powdered metallic material 47 is driven vertically in its entirety by the pitch p, inside the cylindrical enclosure 12. If necessary, the first transducer 34 is implemented to facilitate the descent of the powdered metallic material.

[0066] Also, the longitudinal transfer edges being spaced apart by a distance substantially greater than that which separates the enclosure edges, just like the front 30 and rear 32 edges which are also spaced apart by a distance substantially greater than that which separates the downstream 16 and upstream 14 edges, when the column of powdered metallic material 47 lowers, the edge of the thickness of powdered material which forms inside the cylindrical enclosure 12 is in no way altered. Edge effects are thus avoided.

[0067] Then, in a fourth step 52, the second actuator 44 is again controlled so as to cause the reverse translational movement of the cylinder. transfer table 28 so that it returns to its initial position on the transfer table 24 as illustrated in [Fig.4]. If necessary, a new quantity of powdered metallic material can be loaded back inside as explained above.

[0068] In this way, during the return movement, on the one hand, the thickness of powdery material engaged inside the cylindrical enclosure 12 is in abutment against the inner edge of the enclosure 12 along the upstream edge 14, while on the other hand, the front edge 30 of the transfer cylinder 28 comes to level the aforementioned thickness which then forms a first layer 54 of powdery metallic material. This first layer 54 is then compact and homogeneous.

[0069] According to an advantageous alternative step 56, but not essential, additional leveling is carried out using the roller 25 as illustrated in [Fig. 5]. In this way, the compactness of the first layer 54 is further increased.

[0070] This alternative step 56 is optional and it is possible to move directly to a fifth step 58, in which a binder 60 is projected in a predefined shape by means of an inkjet type injection device 62.

[0071] Then, in a sixth step 64, it is verified that the deposit of the number of layers Ne of powdered metallic material is not reached. And this is obviously not the case after the first layer. And consequently, we return to the first step 46 during which the transfer cylinder 28 is filled.

[0072] In the second step 48, the transfer cylinder 28 extends again in line with the enclosure 12. And, the column of powdered metallic material 47 then comes into contact with the first layer 54. The platform 18 is then lowered by the predetermined step p to deposit a new thickness inside the cylindrical enclosure 12, which thickness bears on the first layer 54.

[0073] According to the fourth step 52, the second actuator 44 is controlled again and during the return movement of the transfer cylinder 28, the front edge 30 of the transfer cylinder 28 comes to level off the aforementioned new thickness which then forms a second layer of powdered metallic material. And this second layer is also compact and homogeneous.

[0074] We then proceed, according to the fifth step 58, to the projection of the binder onto the surface of this second layer according to a predefined shape consistent with the previous projections.

[0075] These steps are repeated until the planned number of layers is reached and when this is the case, a final step 66 causes the installation to stop.

[0076] The green part thus produced is homogeneous in that the bound particles of the powdered metallic material are uniformly distributed in the body of the part. In addition, thanks to the strong compaction of the layers of powdered material, the part has very little free space.

[0077] Consequently, after the green part has been extracted from the free particles of the powdery material surrounding it, it is taken to a furnace for sintering. Thanks to the process according to the invention, the part then obtained has very few occlusions. And its mechanical resistance is then increased.

[0078] Furthermore, thanks to the original compactness of the bound particles of the powdered metallic material, a plurality of the same part produced according to this same method using the installation 10 according to the invention, has extremely small dimensional differences.

Claims

Claims

1. An additive manufacturing installation (10) for a three-dimensional metal part comprising: - a cylindrical enclosure (12) adapted to be oriented vertically and a platform (18) mounted to move in translation inside said enclosure (12); - a storage tank (36) for a powdered metallic material located in the vicinity of said cylindrical enclosure (12); - a transfer device (28) mounted to move horizontally in translation relative to said cylindrical enclosure (12) to be able to sequentially transfer a plurality of given quantities of said powdered metallic material from said reservoir to said enclosure, and to superimpose a plurality of layers (54) of said metallic material on said platform (18) as said platform is lowered into said cylindrical enclosure; - a bonding device (62) for bonding said powdered metallic material of each of the layers according to predefined patterns;characterized in that said transfer device comprises a transfer table (24) installed at the edge of said cylindrical enclosure (12), and a transfer cylinder (28) erected on said transfer table; and in that said transfer cylinder (28) is adapted to receive said powdered metallic material from said storage tank (36) and to be driven in translation from the transfer table (24) to said cylindrical enclosure (12) to superimpose the layers of said metallic material.;

2. Additive manufacturing installation according to claim 1, characterized in that said binding device comprises a printing member (62) for printing a binder (60) according to said predefined patterns on the surface of each of the layers of said powdered metallic material.

3. Additive manufacturing installation according to claim 1 or 2, characterized in that said transfer cylinder (28) has a cross section substantially identical to the cross section of said cylindrical enclosure (12).

4. Additive manufacturing installation according to any one of claims 1 to 3, characterized in that said transfer cylinder (38) has two edges of contact with said transfer table which are substantially parallel.

5. Additive manufacturing installation according to any one of claims 1 to 4, characterized in that said storage tank (36) is installed in line with said transfer table (24).

6. Additive manufacturing installation according to any one of claims 1 to 5, characterized in that it comprises a flexible conduit extended between said storage tank (36) and said transfer cylinder (28).

7. Additive manufacturing installation according to any one of claims 1 to 6, characterized in that said storage tank (36) comprises a hopper equipped with a chute (38) with controllable opening.

8. Additive manufacturing installation according to any one of claims 1 to 7, characterized in that it comprises a transducer (34) mounted on said transfer cylinder (28).

9. Additive manufacturing installation according to any one of claims 1 to 8, characterized in that said platform (18) is lowered into said cylindrical enclosure (12) when said transfer cylinder (28) comes in line with said cylindrical enclosure.

10. Additive manufacturing installation according to any one of claims 1 to 9, characterized in that it comprises a leveling device (23) mounted movable in translation on said cylindrical enclosure (12).

11. A method for additively manufacturing a three-dimensional metal part comprising the following steps: - a cylindrical enclosure (12) is provided, adapted to be oriented vertically, and a platform (18) mounted to move in translation inside said enclosure; - a storage reservoir (36) of a powdered metallic material is provided, located in the vicinity of said cylindrical enclosure (12); - a plurality of given quantities of said metallic material are transferred sequentially in a horizontal direction from said reservoir (36) to said enclosure (12); - a plurality of layers (54) of said metallic material are superimposed on said platform (18), while said platform is lowered gradually into said cylindrical enclosure (12); - said powdered metallic material of each of the layers is bonded according to predefined patterns; characterized in that a transfer table (24) is further provided. installed at the edge of said cylindrical enclosure (12), and a transfer cylinder (28) erected on said transfer table, said transfer cylinder (28) being adapted to receive said powdered metallic material from said storage tank (36); and in that said transfer cylinder (28) is driven in translation from the transfer table (24) to said cylindrical enclosure (12) to superimpose the layers of said metallic material.

12. Additive manufacturing method according to claim 11, characterized in that a binder (62) is printed according to said predefined patterns on the surface of each of the layers of said metallic material to bind said powdered metallic material.

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