FLEXIBLE SUPPORT FOR ADDITIVE MANUFACTURING OF A PART BY LASER FUSION ON A POWDER BED

Abstract

Support (3) for additive manufacturing of a part (1) obtained by laser powder bed fusion comprising a base (4), a foot (5) extending from the base (4) and a head (6) provided at the end of the foot (5), said head (6) comprising an upper surface (7) for supporting a part (1) machined by additive manufacturing. The foot (5) of the support (3) comprises at least one elastically deformable zone along an axis (Y) orthogonal to the base of the support, said elastically deformable zone being configured so that the mechanical stresses of the support (3) exerted on the part (1) are minimized during additive manufacturing. Figure for abstract: Fig 1

Description

Title of the invention: FLEXIBLE SUPPORT FOR ADDITIVE MANUFACTURING OF A PART BY LASER FUSION ON A POWDER BED Technical field

[0001] The present invention relates to the field of additive manufacturing of parts by laser fusion on a powder bed.

[0002] Additive manufacturing by laser fusion on a powder bed, which constitutes an alternative to machining processes by material subtraction, consists of selectively and iteratively depositing and consolidating a layer of powder in order to constitute, layer after layer, a three-dimensional object.

[0003] Additive manufacturing of an object by laser powder bed fusion generally involves the use of a manufacturing tray which serves as a base for manufacturing the object, a device for spreading powder of a predetermined material on the tray, with a desired thickness, and one or more lasers scanning an area of ​​the deposited powder to transform it into a solid bead. This process is carried out on several successive layers which will form the final object.

[0004] The equipment used in this process is generally controlled from a digital production file resulting from the cutting into slices of given thickness of an object modeled by CAD (Computer Aided Design). This is particularly the case for the spreading device and the laser(s), the scanning pattern of which, as well as all the lasing parameters, such as the laser power, the scanning speed, the spacing between two laser passes, etc., are dictated by the production file.

[0005] Passing the laser over the powder bed raises the temperature of the powder to a temperature above its melting temperature. A molten bath is thus created. As it cools, this bath consolidates and forms a solid metal bead. After laser scanning a layer of powder, a two-dimensional section of the desired object is thus obtained.

[0006] Conventional additive manufacturing processes using laser powder bed fusion have a number of limitations, particularly related to the shape of the part to be produced.

[0007] It is indeed difficult to produce parts having faces forming an angle relative to the direction of the stacking of the layers greater than a limit value, for example of the order of 45°.

[0008] In this case, but also when the object to be produced includes areas in cantilever overhang, a support must be used to support the inclined faces of the part or the overhanging areas and thus prevent them from breaking or deforming during additive manufacturing, due to thermomechanics.

[0009] Such support is only useful during additive manufacturing and is then removed.

[0010] The supports used today in additive manufacturing are solid, full volume supports and in particular allow good adhesion of the part to the manufacturing plate.

[0011] However, during additive manufacturing, mechanical stresses are exerted on the part, causing it to deform if it is not sufficiently supported by a support, and causing it to crack if the support is too rigid. Statement of the invention

[0012] The aim of the present invention is to propose a support for manufacturing a part manufactured by laser fusion on a powder bed which ensures that the part is held during manufacturing while limiting the consequences caused by the mechanical stresses exerted on the part.

[0013] The invention therefore relates to a support for additive manufacturing of a part by laser fusion on a powder bed comprising a base, a foot extending from the base and a head provided at the end of the foot, said head comprising an upper surface for supporting a part produced by additive manufacturing. The foot of the support comprises at least one elastically deformable zone along an axis orthogonal to the base of the support, said elastically deformable zone being configured so that the mechanical stresses of the support exerted on the part are minimized during additive manufacturing. Said elastically deformable zone is also configured so that the deformations along an orthogonal axis of the part do not exceed the value of the thickness of a layer of powder during additive manufacturing.

[0014] The deformable support thus makes it possible to support the part and allow additive manufacturing of inclined or overhanging areas, while allowing deformation of the part in order to prevent it from cracking under the effect of mechanical stresses exerted on the part during additive manufacturing.

[0015] In various embodiments, the elastically deformable zone comprises an alternation of solid parts and hollow parts distributed in the axis orthogonal to the base of the support.

[0016] According to a first embodiment, the foot comprises a non-planar surface undulating relative to the axis orthogonal to the base of the support.

[0017] According to a second embodiment, the foot comprises a flat surface which comprises holes aligned with respect to the axis orthogonal to the base of the support so as to form, in the foot, a corrugation with respect to said axis orthogonal to the base of the support.

[0018] Advantageously, the undulation comprises a half-period of between 1 millimeter and 100 millimeters, and preferably between 1 millimeter and 50 millimeters.

[0019] According to another characteristic of the support, the undulation also comprises an amplitude of between 1 millimeter and 50 millimeters, and preferably between 1 millimeter and 20 millimeters.

[0020] Advantageously, the foot of the support comprises a thickness of material between 0.2 millimeters and 5 millimeters, and preferably between 0.5 millimeters and 2 millimeters.

[0021] Optionally, the head of the support comprises a height between 0 millimeters and 50 millimeters.

[0022] In one embodiment, the support includes a fillet that extends from a lower surface of the base of the support.

[0023] For example, the radius of the fillet is between 0.2 millimeters and 5 millimeters, and preferably between 0.5 millimeters and 3 millimeters. Brief description of the drawings

[0024] Other aims, characteristics and advantages of the invention will appear on reading the following description, given solely by way of non-limiting example and made with reference to the appended drawings in which:

[0025] - Figure [Fig.l] is a schematic perspective view of a sector of a room produced by additive manufacturing using laser powder bed fusion, showing the use of a corrugated support;

[0026] - figure [Fig.2] is a schematic sectional view of a support for the part of the [Fig.l];

[0027] - Figure [Fig.3] is a schematic perspective view of another example of implementation implementation of an additive manufacturing process by laser fusion on a powder bed for the production of a part comprising a perforated support;

[0028] - Figure [Fig.4] is a schematic sectional view of an example of a support for variable flexibility of an additively manufactured part, which includes a perforated foot;

[0029] - figure [Fig.5A] is a side view of a variable flexibility support of the part of [Fig.3]; and

[0030] - figure [Fig.5B] is a front view, on a larger scale, of the support of the [Fig.5A], showing the perforations made in the foot of the support. Detailed description

[0031] [Fig.l] shows a first example of the production of a part 1 obtained by implementing an additive manufacturing process by laser fusion on a bed of powder.

[0032] In [Fig.l], the part 1 is represented in a position assumed to be vertical, in an orthonormal X, Y, Z reference frame. The X axis designates the radial direction of the part, the Y axis designates the vertical direction, and the Z axis designates the direction normal to the radial X axis.

[0033] As indicated previously, such a three-dimensional shaping method consists of depositing on a manufacturing plate a layer of powder of a predetermined material, spreading the layer of powder on the manufacturing plate according to a desired thickness, corresponding to the thickness of a slice of an object modeled by CAD and cut into slices, and selectively consolidating the layer of powder by selective scanning of one or more laser beams, these steps being repeated iteratively in order to constitute, layer after layer, a three-dimensional object.

[0034] In [Fig.l], the part 1 illustrated corresponds to the part 1 obtained after implementing the different iterations. It is for example made from a bed of metal powder.

[0035] As indicated previously, when the part 1 includes cantilevered or inclined areas, it is appropriate to use supports which make it possible to support these areas which are difficult to produce.

[0036] In [Fig.l], the part 1 comprises a cantilevered zone 2 supported by a support 3.

[0037] The support 3 comprises at least one elastically deformable zone in order, on the one hand, to support the cantilevered zone 2 while allowing controlled deformation of this zone 2 in order to reduce the stresses of the part 1 and to avoid cracking caused by the effect of the thermomechanical forces intrinsic to manufacturing by laser fusion on a powder bed.

[0038] The support 3 shown in Figures 1 and 2 comprises a base 4, a foot 5 which extends from the base 4 and a head 6 mounted at the end of the foot 5 which comprises an upper surface 7 for supporting the zone 2. The base 4 rests on the manufacturing plate P on which the part 1 is manufactured.

[0039] In the embodiment of Figures 1 and 2, the foot 5 of the support 3 comprises an elastically deformable zone comprising a non-planar surface which undulates relative to an axis II orthogonal to the plane of the base 4 of the support 3, parallel to the plane of the upper face of the manufacturing plate P on which the part 1 is manufactured.

[0040] In other words, the foot 5 is generally sinusoidal and comprises, in cross-section visible in [Fig. 2], on each side relative to the axis II, between the foot 5 and the head 6, a succession of folds forming alternately concave and convex curves placed on either side of the axis II in which the support forces of the part 1 during manufacture are exerted.

[0041] Thus, in the Y direction, in sagittal section relative to a plane perpendicular to the X axis, and from top to bottom, the foot 5 comprises a succession of solid parts and hollow parts facilitating the elastic deformation of the support 3.

[0042] The undulations of the foot 5 give the support 3 a flexibility making it possible to reduce the mechanical stresses in the part 1 during manufacture.

[0043] The geometric characteristics of the foot 5 are chosen in order to modulate the stiffness of the support 3 to allow axial deformation of the foot 5 under the effect of the forces applied by gravity by the zone of the part 1 supported in the direction of the axis II, while ensuring support of the part 1 during manufacture within the elastic limits of the material of the part 1.

[0044] Thus, for example, in an embodiment suitable for the manufacture of an aircraft part 1 consisting of horizontal bearing surfaces acting as flanges or annular bearing surfaces for example, the undulation of the foot 5 of the support 3 comprises a half-period T of between 1 millimeter and 100 millimeters, and preferably between 1 millimeter and 50 millimeters and an amplitude F of between 1 millimeter and 50 millimeters, and preferably between 1 millimeter and 20 millimeters. In [Fig. 2], the undulation of the foot 5 of the support 3 comprises three half-periods T, the number of half-periods, and therefore of folds of the foot, being able to be adapted according to the desired flexibility.

[0045] The foot 5 of the support 3 comprises a thickness E of material between 0.2 millimeters and 5 millimeters, and preferably between 0.5 millimeters and 2 millimeters, and the head 9 of the support 3 comprises a height H between 0 millimeters and 50 millimeters.

[0046] Each support 3 optionally comprises a fillet of radius R extending from the lower surface of the base 4 of the support 3. The radius R is between 0.2 millimeters and 5 millimeters, and preferably between 0.5 millimeters and 3 millimeters.

[0047] [Fig. 3], in which elements identical to those described previously with reference to FIGS. 1 and 2 are designated by the same numerical references, shows a second embodiment of a support 3 with variable flexibility.

[0048] [Fig. 3] shows a part 1 supported by a flexible support 3. The support 3 shown in [Fig. 3] comprises a base 4, a foot 5 which extends from the base 4 and a head 6 provided at the upper end of the foot 5 which comprises an upper surface 7 for supporting a cantilevered area of ​​the part 1.

[0049] In this second embodiment, the foot 5 of the support 3 comprises an elastically deformable zone comprising a flat surface which comprises holes 8 aligned along the vertical axis Y orthogonal to the base 4 of the support 3. The holes 8 are through and made in the direction of the transverse axis X.

[0050] As in the embodiment described previously with reference to figures 1 and 2, in the direction of axis II in which the forces are exerted on the support 3, the foot 5 comprises a succession of solid parts and empty parts, facilitating the elastic deformation of the support 3.

[0051] The geometric characteristics of the foot 5 are also chosen in order to modulate the stiffness of the support 3 in order to allow deformation along the axis (Y) of the foot 5 under the effect of the forces applied by gravity by the zone of the part 1 supported in the direction of the axis II, while ensuring support of the part 1 during manufacture within the elastic limits of the material of the part 1.

[0052] Thus, the foot 5 of the support 3 comprises a thickness E of material between 0.2 millimeters and 5 millimeters, and preferably between 0.5 millimeters and 2 millimeters.

[0053] The number of holes 8 made in the foot 5 is also chosen so as to allow deformation of the support 3 within the limits of the elastic deformation of the part 1 during manufacture.

[0054] As illustrated in Figures 5A and 5B, the alignment of the holes 8 forms a corrugation in the foot 5 which extends in the Y direction orthogonal to the base 4 of the support 3.

[0055] This ripple comprises a half-period T of between 1 millimeter and 100 millimeters, and preferably between 1 millimeter and 50 millimeters, and an amplitude F of between 1 millimeter and 50 millimeters, and preferably between 1 millimeter and 20 millimeters. In [Fig.5B], the ripple comprises six half-periods T.

[0056] For example, the holes 8 have a radius r of between 0.3 millimeters and 5 millimeters, and preferably between 0.6 and 3. The number of holes 8 made on a support 3 comprising a perforated foot 5 varies according to different parameters such as the spacing between the holes, the height of the foot and the diameter of the desired holes. Of course, it does not depart from the scope of the invention when the foot is provided with a different number of holes or comprises a single slot of dimensions chosen to provide sufficient rigidity to support the part within the limits of its elastic deformation. The thickness e between each hole 8 is between 0.2 millimeters and 5 millimeters, and preferably between 0.5 millimeters and 3 millimeters.

[0057] As in the embodiment described previously with reference to Figures 1 and 2, the support 3 comprises an optional fillet of radius R extending from the lower surface of the base 4 of the support 3. The radius R is between 0.2 millimeters and 5 millimeters, and preferably between 0.5 millimeters and 2 millimeters.

[0058] The advantage of the supports 3 is to limit the mechanical stresses exerted on the part 1 during its manufacture by laser powder bed fusion. They act like a spring, making it possible to support the part 1 to prevent it from deforming, while being sufficiently flexible not to block the part 1 if it has to deform under stress. Thus, deformations and cracks in the part 1 are limited, or even avoided.

[0059] Of course, the embodiment illustrated in Figures 3 and 4 is also combinable with the embodiment of Figures 1 and 2, in that corrugated supports 3 can be used in conjunction with perforated supports 3, and in that a corrugated support 3 can also be perforated.

Claims

Claims

1. Support (3) for additive manufacturing of a part (1) by laser fusion on a powder bed comprising a base (4), a foot (5) extending from the base (4) and a head (6) provided at the end of the foot (5), said head (6) comprising an upper surface (7) for supporting the part (1), characterized in that the foot (5) comprises at least one elastically deformable zone along an axis (Y) orthogonal to the base of the support, said elastically deformable zone being configured so that the mechanical stresses of the support (3) exerted on the part (1) are minimized during additive manufacturing.

2. Support according to claim 1, in which the elastically deformable zone comprises an alternation of solid parts and hollow parts distributed in the axis (Y) orthogonal to the base of the support.

3. Support (3) according to one of claims 1 and 2, in which the foot (5) comprises a non-planar corrugated surface, the corrugation of the support extending relative to the axis (Y) orthogonal to the base (4) of the support (3).

4. Support (3) according to any one of claims 1 to 3, in which the foot (5) comprises holes (8) aligned with respect to the axis (Y) orthogonal to the base (4) of the support (3) so as to form, in the foot, a corrugation with respect to said axis (Y) orthogonal to the base (4) of the support (3).

5. Support (3) according to one of claims 3 and 4, in which the undulation comprises a half-period (T) of between 1 millimeter and 100 millimeters, and preferably between 1 millimeter and 50 millimeters.

6. Support (3) according to any one of claims 3 to 5, in which the undulation comprises an amplitude (F) of between 1 millimeter and 50 millimeters, and preferably between 1 millimeter and 20 millimeters.

7. Support (3) according to any one of claims 1 to 6, in which the foot (5) of the support (3) comprises a thickness (E) of material between 0.2 millimeters and 5 millimeters, and preferably between 0.5 millimeters and 2 millimeters.

8. Support (3) according to any one of claims 1 to 7, wherein the head (6) of the support (3) comprises a height (H) of between 0 millimeters and 50 millimeters.

9. Support (3) according to any one of claims 1 to 8, which comprises a fillet extending from a lower surface of the base (4) of the support (3), said fillet having a radius (R) of between 0.2 millimeters and 5 millimeters, and preferably between 0.5 millimeters and 2 millimeters.

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