Method for the powder-based additive manufacturing of a part, notably a lining blade for a tire mould, with an associated reinforcing element

Abstract

Process for the additive manufacturing of at least one part by powder sintering or melting using at least one beam of energy. A step of deposition and selective melting of stacked layers of powder manufactures at least one intermediate element comprising the part and at least one local reinforcing element having a split tubular shape that surrounds one of the lateral end faces of the part and that face each of the frontal faces of said part adjacent to said end face, said reinforcing element extending in a direction substantially parallel to the stacking direction of the layers. The part and the local reinforcing element are separated.

Claims

1. A process for the additive manufacturing of at least one part by powder sintering or melting using at least one beam of energy, said part comprising at least two opposite frontal faces and at least two lateral end faces, the process comprising the following steps: a) manufacture, by deposition and selective melting of stacked layers of powder, of at least one intermediate element comprising the part and at least one local reinforcing element having a split tubular shape that surrounds one of the lateral end faces of the part and that face each of the frontal faces of said part adjacent to said end face, a portion of the part extending through the slit of the local reinforcing element and into said reinforcing element, the other portion of the part protruding outside of the reinforcing element, said reinforcing element extending in a direction substantially parallel to the stacking direction of the layers, wherein during the manufacturing step, for each fused layer of powder of the part and each fused layer of powder of the local reinforcing element, the deposited powder present between each frontal face of said fused powder layer of the part and the facing end face of said fused powder layer of the reinforcing element is completely or partially fused by heat diffusion and not directly by the beam of energy, and b) after manufacture, gripping said other portion of the part protruding outside of the reinforcing element separation of the part and of the local reinforcing element by pulling along a direction perpendicular to the stacking direction of the layers.

2. A process according to claim 1, wherein the fused powder layers of the part and of said local reinforcing element are joined to one another during the manufacturing step.

3. A process according to claim 1, wherein said local reinforcing element is configured so as to reinforce the part at least in a direction substantially perpendicular to the stacking direction of the layers.

4. A process according to claim 1, wherein unfused powder fills a space that exists between an inner surface of said local reinforcing element and the part before the separation step.

5. A process according to claim 1, wherein according to a modelled melting of a layer of powder of the local reinforcing element and of a layer of powder of the part, a gap is provided between each end face of the layer of the reinforcing element and the frontal face of the layer of the part which is facing said end face, said gap being between 0.01 mm and 1 mm.

6. A process according to claim 1, wherein said local reinforcing element extends over the entire height of the part.

7. A process according to claim 1, wherein a plurality of intermediate elements is manufactured simultaneously at least as a matrix of columns and rows.

8. A process according to claim 7, wherein the reinforcing elements of at least one column or of at least one row are produced as one piece.

9. Intermediate element obtained by implementation of the process according to claim 1.

10. A process according to claim 1, wherein according to a modelled melting of a layer of powder of the local reinforcing element and of a layer of powder of the part, a gap is provided between each end face of the layer of the reinforcing element and the frontal face of the layer of the part which is facing said end face, said gap being less than or equal to 0.1 mm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention will be understood better from reading the detailed description of embodiments considered by way of entirely non-limiting examples and illustrated by the appended drawings, in which:

(2) FIG. 1 is a schematic perspective view partially illustrating a process for manufacturing blades according to a first example of implementation,

(3) FIG. 2 is a perspective view of an intermediate element obtained during the manufacturing process of FIG. 1 and that comprises one of the blades and a local reinforcing element,

(4) FIG. 3 is a schematic top view illustrating layers of the intermediate element of FIG. 2 after selective melting modelled by a computer,

(5) FIG. 4 is a schematic top view illustrating layers of the intermediate element of FIG. 2 after selective laser melting,

(6) FIG. 5 is a schematic perspective view partially illustrating a process for manufacturing blades according to a second example of implementation,

(7) FIG. 6 is a schematic top view illustrating an intermediate element obtained during a third example of implementation of the manufacturing process, and

(8) FIGS. 7 to 9 are perspective views of an intermediate element obtained during fourth, fifth and sixth examples of implementation of the manufacturing process.

DETAILED DESCRIPTION OF THE DRAWINGS

(9) Represented in FIG. 1 is an arrangement of identical blades 10 which are intended for a tire vulcanizing mould and are formed on a manufacturing plate 12 represented in an assumed horizontal position. Each blade 10 is associated with a local reinforcing element 14 surrounding only one of the ends of said blade. The reinforcing elements 14 are identical to one another. The plate 12 comprises an upper surface forming a working surface 12a on which the blades 10 and the reinforcing elements 14 are formed. The blades 10 and the reinforcing elements 14 are respectively identical to one another.

(10) As illustrated more clearly in FIG. 2, each blade 10 has a rectangular general shape. The length of the blade extends substantially perpendicular relative to the working surface 12a of the manufacturing plate, i.e. here substantially vertically. The blades 10 are oriented or extend substantially vertically. In other words, the length of the blade constitutes its height.

(11) The blade 10 here has a curved shape. In the embodiment illustrated, each blade 10 comprises a main body 10a and a head 10b made in one piece with said body. The body 10a comprises two opposite main frontal faces 10c, 10d and two opposite lateral end faces 10e, 10f delimiting said frontal faces. The main frontal faces 10c, 10d delimit the thickness of the body 10a of the blade. In the exemplary embodiment illustrated, the main faces 10c, 10d are flat. As variants, these faces could have another shape, for example a wavy shape. The head 10b prolongs the end face 10e of the body and extends parallel to the length of the body. The head 10b here has a substantially cylindrical shape with a triangular cross section. As a variant, the cross section of the head could have any other shape, for example rectangular, square, circular, etc., or else V-shaped or U-shaped. The blade 10 is capable of enabling the moulding of a water drop pattern in the tread of the tire

(12) Each reinforcing element 14 surrounds the end face 10f of the associated blade and faces the frontal faces 10c, 10d. Each reinforcing element 14 comprises two end faces 14a, 14b that face the frontal faces 10c, 10d of the blade. The reinforcing element 14 has a split tubular shape. A portion of the blade 10 extends inside the reinforcing element 14 through the slit delimited by the end faces 14a and 14b, the other portion of the blade being located outside of said reinforcing element. Each reinforcing element 14 extends substantially perpendicular relative to the working surface 12a of the manufacturing plate. Each reinforcing element 14 here has a length substantially equal to that of the associated blade 10.

(13) The following procedure is used for the manufacture of the plurality of blades 10. In a first step, a first layer of powder is deposited on the working surface 12a of the manufacturing plate. After deposition, the first layer extends substantially horizontally over the working surface 12a. The powder may for example be metallic or mineral, for example ceramic.

(14) In a second step, an energy source (not represented), for example of laser type, emits a laser beam, the orientation of which is controlled by galvanometric mirrors (not represented). An optical lens (not represented) makes it possible to focus the laser beam in order to heat the layer of powder in a pattern corresponding to the cross section of the blade 10 to be manufactured and to the cross section of the associated reinforcing element 14, and thus to selectively carry out the melting of the powder. This selective melting is carried out in each zone of the working surface 12a of the manufacturing plate on which a blade 10 and the associated reinforcing element 14 should be manufactured.

(15) As illustrated in FIG. 3, the control of the laser beam is modelled by a computer so as to theoretically obtain, on the working surface 12a of the manufacturing plate, a first fused powder layer C.sub.1,10 and a first fused power layer C.sub.1,14 respectively for the formation of the blade 10 and of the associated reinforcing element 14. In this figure, the powder deposited previously and not sintered is illustrated by dots. As modelled, a gap 16 is provided between each end face of the fused powder layer C.sub.1,14 of the reinforcing element and the frontal face of the fused power layer C.sub.1,10 of the blade. This gap is between 0.01 mm and 1 mm, and advantageously between 0.05 and 0.2 mm, and preferably less than or equal to 0.1 mm.

(16) In practice, with a theoretical gap 16 of less than or equal to 0.1 mm, under the effect of the sintering of the first fused powder layers C.sub.1,10 and C.sub.1,14, the deposited powder present between each end face of the layer C.sub.1,10 and the frontal face of the layer C.sub.1,14 is completely or partly fused by diffusion of the heat joining said layers of the blade 10 and of the reinforcing element 14 being formed. The attachment that exists between these layers is illustrated schematically in FIG. 4. This attachment creates a link between the blade 10 and the reinforcing element 14 which may be broken manually, as specified subsequently. A base player of the fused powder layers refers to the lower layer C.sub.1,10, C.sub.1,14 on which, respectively, the blade 10 and the reinforcing element 14 rest.

(17) During a third step, after the laser treatment step, a second layer is deposited on the first powder layer which is partly fused. Next, the selective melting of the second layer is carried out as before. These steps are repeated again in order to form, by stacking of fused layers, the blades 10 and the associated reinforcing elements 14. The fused layers of each blade 10 and of each reinforcer 14 extend substantially horizontally and are stacked on top of one another in a substantially vertical stacking direction. Each reinforcing element 14 makes it possible to reinforce the associated blade 10 at least in a direction substantially perpendicular to the stacking direction of the layers.

(18) Thus, a plurality of intermediate elements, each comprising the blade 10 and the associated local reinforcing element 14, is manufactured. In the exemplary embodiment illustrated, for each intermediate element manufactured, the blade 10 and the reinforcing element 14 are produced as one piece. The reinforcing element 14 that surrounds the end face 10f of the blade and bears on either side against the main faces 10c, 10d of this end face makes it possible to ensure that said blade in the process of being manufactured is held in position. This further limits the risk of deformations, in particular by bending during the passage of the layering device and by diffusion of the heat during the melting steps, which may give rise to the appearance of stress concentration and microcrack phenomena. Moreover, the presence of unsintered powder, trapped and compacted in the space that exists between the blade 10 and the bore of the reinforcing element 14 forming an inner surface further promotes a good holding of the blade. The reinforcing element 14 only bears against the main faces 10c, 10d of the blade 10 and not against the end face 10f.

(19) As illustrated in FIG. 1, after manufacture, the intermediate elements each constituted by a blade 10 and the associated reinforcing element 14 are arranged on the plate 12 as a matrix of parallel columns and rows. The intermediate elements may then be detached from the manufacturing plate 12, for example by cutting by electro-erosion by wire. Finally, during a last step, the blades 10 and the reinforcing element 14 of each intermediate element are detached from one another by pulling, which may for example be manual, so as to keep only the blades. The tensile force exerted in order to carry out this detachment is oriented perpendicular to the stacking direction of the powder layers. Moreover, the portion of the blade 12 protruding outside of the reinforcing element 14 facilitates the gripping for carrying out this detachment.

(20) In the exemplary embodiment illustrated, the intermediate elements of each column are manufactured so as to be aligned and spaced out relative to one another. As a variant, it is possible to make provision for the manufacture of the intermediate elements so that the reinforcing elements 14 of each column are produced as one piece, as illustrated in the embodiment variant from FIG. 5 in which identical elements bear the same references. This makes it possible to further increase the stiffness of the assembly thus obtained and to limit the risk of deformations of the blades 10 of this assembly. This also facilitates the handling of the assembly after cutting. In addition, after cutting of the intermediate elements from the manufacturing plate 12, the blades 10 of a same column may then be detached from their reinforcing elements 14 in a single operation.

(21) In the preceding exemplary embodiments, the blades 10 have a general rectangular shape and are designed to enable the moulding of a water drop type pattern. Since the cross section of the head 10b of each blade is relatively large, this head has a sufficient stiffness not to require the provision of a local reinforcer in this zone.

(22) As a variant, it is possible to manufacture blades 10 having other shapes, for example without heads 10b. In this case, it may be possible to provide a reinforcing element on each end face of the body of the blade. In another variant illustrated in FIG. 6, it is possible to provide a blade 10 comprising two arms 10g, 10h that extend from the end face 10e. A reinforcing element 14 is provided here around the free end face of each arm 10g, 10h and faces the frontal faces of said arm which are adjacent to said end face.

(23) In the exemplary embodiment illustrated, each reinforcing element 14 has a split tubular shape of C-shaped circular cross section. Alternatively, it is possible to provide reinforcing elements 14 having a split tubular shape having a cross section that is polygonal, such as triangular, rectangular or square, as is illustrated respectively in the embodiment variants from FIGS. 7 to 9. As a variant, it is also possible to provide reinforcing elements having a split tubular shape having a cross section that is polygonal, such as hexagonal, octagonal, etc., or else reinforcing elements of elliptical cross section. A portion of the blade to be stiffened extends through the slit and into the reinforcing element 14, the other portion of the blade being located outside of said reinforcing element.

(24) In the exemplary embodiments illustrated, the main body 10a of the blade extends substantially vertically. As a variant, the body of the blade could have a curved profile. In this case, the slit of the reinforcing element has a similar profile so as to follow the curvature of the blade.

(25) In the exemplary embodiments illustrated in FIGS. 1 to 6, each reinforcing element extends over the entire length of the blade to be stiffened. As a variant, it is possible to provide reinforcing elements that each extend over a portion of the length of the associated blade. This may for example be the case when the blade has one zone with a thin cross section and one zone with a thick cross section. In this case, the reinforcing element may be provided only around the zone of the blade having a thin cross section.

(26) The invention has been described on the basis of a vertical-type manufacture of blades 10, the length of each blade extending substantially vertically relative to the working surface 12a of the plate. As a variant, it is possible to make provision for a horizontal-type manufacture in which the length of the blade is substantially parallel to the manufacturing plate and perpendicular to the stacking direction. In this case, two local reinforcing elements may be provided in order to each surround longitudinal ends of the blade. The local reinforcing elements may then essentially have a role of supporting the blade when the intermediate element, which is formed by this blade and the reinforcing elements, is detached from the manufacturing plate.

(27) The invention has been described on the basis of a laser sintering manufacture of a blade for a mould for vulcanizing tires. The invention may also be applied to another lining element of the mould intended to be added to a support block of the mould, or more generally to other types of small-sized parts used in different applications.

(28) The scope of protection of the invention is not limited to the examples given hereinabove. The invention is embodied in each novel characteristic and each combination of characteristics, which includes every combination of any features which are stated in the claims, even if this feature or combination of features is not explicitly stated in the examples.