METHOD FOR PRODUCING A CHAMFER ON A PART DURING AN ADDITIVE MANUFACTURING STAGE

Abstract

The invention relates to a method for manufacturing a part (20) comprising at least one internal cavity (21) including: - a step of producing, by additive manufacturing, walls (23.1-23.4) delimiting the internal cavity (21), and during said additive manufacturing step, a cone shape (25) or truncated cone shape (26) is formed in an internal face (30) of one of the walls, referred to as the wall to be drilled (23.1), and - a step of drilling the wall to be drilled (23.1) so as to obtain a through ventilation opening (34), - a larger diameter of the cone shape (25) or truncated cone shape (26) being greater than a diameter of the through ventilation opening (34), so that after the drilling step, a residual chamfer is obtained at one end of the through ventilation opening (34). Figure 3b

Description

Title of the invention: METHOD FOR CREATING A CHAMFER ON A PART DURING AN ADDITIVE MANUFACTURING PHASE

[0001] The present invention relates to a method for creating a chamfer on a part during an additive manufacturing phase. The invention finds a particularly advantageous application with the additive manufacturing process by laser beam melting (LBM).

[0002] The LBM process is a part shaping process that contrasts with so-called "conventional" subtractive processes (machining). It consists of the selective consolidation of powder layers to build up, layer by layer, a three-dimensional object.

[0003] During the implementation of an LBM process, a digital production file is created using appropriate software. This file is generated by slicing the CAD model of an object into layers of a given thickness. The production file contains all the instructions necessary for the LBM system to produce an object, layer by layer.

[0004] In the LBM system, a build platform serves as the base for manufacturing an object. A powder spreading device allows a layer of powder of the desired material to be spread onto the build platform, to a desired thickness. This device can be a roller or a scraper that moves in translation along an axis on either side of the powder bed.

[0005] Once the powder layer has been deposited, one (or more) laser(s) selectively scan certain areas of the powder bed corresponding to a slice of the object to be produced.

[0006] The scanning pattern as well as all laser-related parameters (such as power The laser's scanning speed, the spacing between laser passes, etc., are all parameters imposed on the LBM system by the production file. Passing the laser over the powder bed raises the powder to a temperature above its melting point, creating a molten pool. As it cools, this pool solidifies, forming a bead of solid material. After the laser scan of a powder layer, a two-dimensional cross-section of the desired object is obtained.

[0007] The powder spreading device then deposits a new layer of powder on top of the previous one. A new laser scan is performed to consolidate a new slice of the object.

[0008] Thus, iteratively, a three-dimensional object is reconstituted by successive consolidation of very thin two-dimensional slices.

[0009] Some parts have ventilation circuits connecting internal cavities to the outside. For this purpose, holes can be machined using a drill-type tool with access from outside the part. However, in some cases, the small size and geometry of the holes and / or the cavity do not allow for the integration of a chamfer into the hole on the cavity side.

[0010] However, the absence of a chamfer generates significant permeability losses and therefore a loss of efficiency in the ventilation system. Indeed, as illustrated in Figures 1a and 1b, a part 1 with a through ventilation opening 2 having a single chamfer 3 exhibits a permeability 4 much lower than a part 1 with a through ventilation opening 2 with double chamfers.

[0011] The invention aims to effectively remedy the aforementioned drawbacks by proposing a method for manufacturing a part comprising at least one internal cavity, including: - a step of producing, by additive manufacturing, walls delimiting the internal cavity, and during said additive manufacturing step, a cone or truncated cone shape is produced in an internal face of one of the walls, called the wall to be drilled, said internal face being turned towards the side of the internal cavity inaccessible by a machining tool, and - a drilling step, along an axis in the shape of a cone or truncated cone, through the wall to be drilled from an external face of the wall to be drilled facing outwards from the internal cavity to the internal face of the wall to be drilled, so as to obtain a through ventilation opening through the wall to be drilled from the external face to the internal face, - a larger diameter of the cone or truncated cone shape being greater than a diameter of the ventilation through opening, so that after the drilling step, a residual chamfer is obtained at one end of the ventilation through opening leading into the internal cavity on the side of the internal face of the wall to be drilled.

[0012] The invention thus makes it possible to form a chamfer at one end of a through-ventilation opening that is inaccessible by machining, in order to significantly limit pressure losses in a ventilation circuit. The invention improves the efficiency of a ventilation circuit implemented in the room.

[0013] According to one embodiment of the invention, said method comprises a step of making a fillet at the level of an interface between a base in the shape of a cone or truncated cone and the inner face of the wall to be drilled.

[0014] According to one embodiment of the invention, said method further comprises a step of machining a chamfer on the side of one end of the through ventilation opening leading to the outside of the internal cavity.

[0015] According to one embodiment of the invention, the additive manufacturing step being carried out by a device comprising a manufacturing platform, the cone or truncated cone shape is produced so that in cross-sectional view, two faces of the cone or truncated cone shape have an angle greater than 40 degrees with respect to a plane passing through the manufacturing platform.

[0016] According to one embodiment of the invention, said method comprises a step of making a part comprising a plurality of internal cavities and corresponding through ventilation openings.

[0017] According to one embodiment of the invention, the additive manufacturing process is a laser melting additive manufacturing process.

[0018] The invention also relates to a part obtained by the process as defined above, comprising: - walls delimiting an internal cavity, - at least one of the walls being a perforated wall having an inner face facing the side of the internal cavity inaccessible by a machining tool and an outer face facing outwards from the internal cavity, - the perforated wall having a through ventilation opening extending from the outer face to the inner face, - a chamfer being provided on the side of one end of the through ventilation opening leading into the internal cavity on the side of the internal face of the wall to be pierced.

[0019] According to one embodiment of the invention, said part has a fillet at the level of an interface between the chamfer and the inner face of the wall to be drilled.

[0020] According to one embodiment of the invention, two faces of a conical shape of the chamfer seen in section have an angle greater than 40 degrees with respect to a horizontal plane.

[0021] According to one embodiment of the invention, said part further comprises a second chamfer on the side of one end of the through ventilation opening leading to the outside of the internal cavity.

[0022] According to one embodiment of the invention, said part comprises a plurality of internal cavities and corresponding through ventilation openings.

[0023] According to one embodiment of the invention, said part is made of a metallic material.

[0024] The present invention will be better understood and other features and advantages will become apparent upon reading the following detailed description, which includes embodiments given by way of illustration with reference to the accompanying figures. presented as non-limiting examples, which may serve to supplement the understanding of the present invention and the explanation of its implementation and, where appropriate, contribute to its definition, on which:

[0025] [Fig. la] [Fig.lb] Figures la and 1b, already described, are cross-sectional views illustrating the difference in permeability between a through ventilation opening with a single chamfer and a through ventilation opening with double chamfers;

[0026] [Fig.2] Fig.2 is a schematic representation of a manufacturing device additive on powder bed allowing the manufacture of a part according to the invention before drilling;

[0027] [Fig.3a] [Fig.3b] [Fig.3c] [Fig.3d] Figures 3a, 3b, 3c and 3d are schematic cross-sectional representations illustrating different stages of the manufacturing process of a part according to the invention;

[0028] [Fig.4] Fig.4 is a cross-sectional view illustrating an alternative embodiment of a chamfer on a part according to the invention;

[0029] [Fig.5a] The [Fig.5a] is a partial perspective view illustrating an alternative embodiment in which a fillet is made at the interface between a cone and the wall of an internal cavity before drilling the through ventilation opening;

[0030] [Fig.5b] The [Fig.5b] is a partial perspective view illustrating the chamfer and corresponding fillet after drilling the through ventilation opening.

[0031] It should be noted that, in the figures, the structural and / or functional elements common to the different embodiments have the same reference numerals. Thus, unless otherwise stated, such elements have identical structural, dimensional and material properties.

[0032] Figure 2 shows a powder bed additive manufacturing device 10 for producing a part 20 with an internal cavity 21. This device 10 includes a build platform 11 that moves vertically and is positioned above a powder reservoir 12. A powder spreading system 13, for example a roller system, is used to even out the thickness of a powder bed 14 deposited on the build platform 11. The device 10 also includes means 15 for generating a laser beam 16 coupled to computer-controlled oscillating mirrors 17 to orient and move the laser beam 16 along the three dimensions X, Y and Z.

[0033] The various stages of the additive manufacturing process for a part 20 having an internal cavity 21 are described below. This process includes a step of depositing a powder bed 14 onto the build platform 11. The powder bed 14 preferably contains a powder made of a metallic material. Alternatively, the powder may be made of a polymer material.

[0034] The roller system 13 spreads the powder to obtain a powder bed 14 having a predetermined thickness.

[0035] The process also includes a laser scanning step of certain areas of the powder bed 14 corresponding to a slice of the part 20 to be produced.

[0036] The scanning pattern and all laser-related parameters (such as laser power, scanning speed, spacing between laser passes, etc.) are imposed on the system by a production file. Passing the laser over the powder bed 14 raises the powder to a temperature above its melting point. A molten bath is thus created. Upon cooling, this bath solidifies and forms a layer of solid material. After the laser scan of a powder layer, a two-dimensional cross-section of the desired part 20 is obtained.

[0037] The manufacturing platform 11 is then moved vertically by a distance equivalent to the thickness of the solidified material layer.

[0038] The powder spreading system 13 then deposits a new layer of powder on top of the previous one. A new laser scan is performed to consolidate a new slice of the part 20. Alternatively, the local melting of the powder bed 14 can be carried out by an electron beam or Electron Beam Melting (EBM) according to Anglo-Saxon terminology or by binder jetting also called "Binder Jetting" according to Anglo-Saxon terminology.

[0039] Thus, iteratively, the successive consolidation of very thin, two-dimensional slices makes it possible to obtain the walls 23.1-23.4 delimiting an internal cavity 21 of the part 20. The internal cavity 21 can be partially opened to connect said cavity 21 to a ventilation circuit. In [Fig. 3a], the arrow F represents the direction of fusion of the different slices of the part 20.

[0040] During the additive manufacturing stage, a cone shape 25 is formed in an internal face 30 of one of the walls, referred to as the wall to be drilled 23.1. The internal face 30 is oriented towards the internal cavity 21, which is inaccessible to a machining tool. The cone shape 25 is thus formed progressively, layer by layer, during the formation of the wall to be drilled 23.1, as indicated by arrow F. The cone shape 25 defines an empty space within the wall to be drilled 23.1.

[0041] Advantageously, the cone shape 25 is constructed such that, in cross-sectional view, two faces of the cone shape 25 have an angle A1, A2 greater than 40 degrees with respect to a plane P passing through the fabrication tray 11, as shown in [Fig. 3a]. Thus, a first angle A1, corresponding to the smallest angle from the plane P of the fabrication tray to the lower face of the cone shape 25, has a value greater than 40 degrees. A second angle A2, corresponding to the smallest angle from the plane of the fabrication tray 11 to the upper face of the cone shape 25, also has a value greater than 40 degrees.

[0042] As illustrated in Figures 3b and 3c, the process then comprises a drilling step, along an axis XI in the shape of a cone 25, of the wall to be drilled 23.1 from an external face 31 of the wall to be drilled 23.1 facing outwards from the internal cavity 21 to the internal face 30 of the wall to be drilled 23.1. This creates a through ventilation opening 34 through the wall to be drilled 23.1 from the external face 31 to the internal face 30. The drilling step is carried out using a drill bit 27.

[0043] A larger diameter of the cone shape 25 is greater than a diameter of the ventilation through opening 34, so that after the drilling step, a residual chamfer 35 is obtained on the side of one end of the ventilation through opening 34 opening into the internal cavity 21 on the side of the internal face 30.

[0044] As illustrated in [Fig.3d], the method may further include a step of machining a chamfer 36 on the side of one end of the through ventilation opening 34 leading to the outside of the internal cavity 21.

[0045] A ventilation airflow 33 can circulate between two external zones adjacent to the internal cavity 21 by passing through an opening 22 made in the wall 23.2 during additive manufacturing, the internal cavity 21, and the through ventilation opening 34.

[0046] Alternatively, as shown in [Fig. 4], the shape formed on the inner face 30 of the wall to be drilled 23.1 is a truncated cone shape 26 to obtain a flat bottom. The truncated cone shape 26 defines an empty space inside the wall to be drilled 23.1. This embodiment makes it possible to ensure a greater wall thickness 23.1 during melting in the case of a thin wall compared to the dimensions of the drill hole and the chamfer 35. This allows the cone to form during melting and increases heat conduction to the fabrication platform 11.

[0047] As illustrated in [Fig. 5a], the method may also include a step of creating a fillet 39 at the interface between a base of the shape of a cone 25 or a truncated cone 26 and the inner face of the wall to be drilled 23.1. A radius of curvature of the fillet 39 can be very small (close to 0) or such that the fillet 39 extends over almost the entire surface of the cone 25 or the truncated cone 26. This makes it possible to improve the permeability of the ventilation opening 34 as well as the manufacturability depending on the angles of the drilling relative to the plate and relative to the limiting manufacturing angles.

[0048] After drilling the opening of the ventilation through opening 34, the resulting part 20 has the fillet 39 at the interface between the chamfer 35 and the inner face of the wall to be drilled 23.1, as illustrated in [Fig.5b].

[0049] The invention also relates to the part 20 visible in [Fig. 3d] obtained by the previously described process, comprising walls 23.1-23.4 delimiting the internal cavity 21. The wall 23.1 is a perforated wall having an internal face 30 facing the side of the internal cavity 21 inaccessible by a machining tool and an external face 31 turned towards the outside of the internal cavity 21.

[0050] The perforated wall 23.1 has a through ventilation opening 34 extending from the outer face 31 to the inner face 30.

[0051] A chamfer 35 is provided on the side of one end of the through ventilation opening 34 opening into the internal cavity 21 on the side of the internal face 30 of the wall to be drilled 23.1.

[0052] Two faces of a conical shape of the chamfer 35 seen in section have an angle Al, A2 greater than 40 degrees with respect to a horizontal plane.

[0053] Part 20 further includes a second chamfer 36 on the side of one end of the through ventilation opening 34 leading outwards from the internal cavity 21.

[0054] Part 20 is preferably made of a metallic material. Alternatively, part 20 is made of a polymer material.

[0055] To facilitate understanding of the invention, only one internal cavity 21 has been shown. However, the part 20 may comprise a plurality of internal cavities 21 and corresponding through ventilation openings 34.

[0056] Of course, the different features, variants and / or embodiments of the present invention can be combined with each other in various ways insofar as they are not incompatible or mutually exclusive.

[0057] Furthermore, the invention is not limited to the embodiments described above and provided solely by way of example. It encompasses various modifications, alternative forms, and other variants that a person skilled in the art may consider within the scope of the present invention, and in particular all combinations of the different modes of operation described above, which may be taken separately or in combination.

Claims

Demands

1. A method for manufacturing a part (20) comprising at least one internal cavity (21), characterized in that it comprises: - a step of producing, by additive manufacturing, walls (23.1-23.4) delimiting the internal cavity (21), and during said additive manufacturing step, a cone shape (25) or truncated cone shape (26) is formed in an internal face (30) of one of the walls, referred to as the wall to be drilled (23.1), said internal face (30) being oriented towards the side of the internal cavity (21) inaccessible by a machining tool, and - a drilling step, along an axis of the cone shape (25) or truncated cone shape (26), of the wall to be drilled (23.1) from an external face (31) of the wall to be drilled (23.1) oriented towards the outside of the internal cavity (21) to the internal face (30) of the wall to be drilled (23.1), so as to obtain a through ventilation opening (34) passing through the wall to be pierced (23.1) from the external face (31) to the internal face (30), - a larger diameter of the cone shape (25) or truncated cone shape (26) being greater than a diameter of the ventilation through opening (34), so that after the drilling step, a residual chamfer (35) is obtained at one end of the ventilation through opening (34) opening into the internal cavity (21) on the side of the internal face (30) of the wall to be drilled (23.1).

2. Method according to claim 1, characterized in that it comprises a step of making a fillet (39) at the level of an interface between a base of the shape of a cone (25) or of a truncated cone (26) and the inner face (30) of the wall to be drilled (23.1).

3. Method according to claim 1 or 2, characterized in that it further comprises a step of machining a chamfer (36) on the side of one end of the through ventilation opening (34) leading to the outside of the internal cavity (21).

4. A method according to any one of claims 1 to 3, characterized in that, the additive manufacturing step being carried out by a device (10) comprising a build platform (11), the cone shape (25) or truncated cone shape (26) is produced such that, in cross-sectional view, two faces of the cone shape (25) or truncated cone shape (26) have an angle (Al, A2) greater than 40 degrees relative to a plane passing through the manufacturing platform (H).

5. A method according to any one of claims 1 to 4, characterized in that it comprises a step of making a part (20) comprising a plurality of internal cavities (21) and corresponding through ventilation openings (34).

6. A method according to any one of claims 1 to 5, characterized in that the additive manufacturing method is a laser melting additive manufacturing method.

7. Part (20) obtained by the process as defined according to any one of the preceding claims, characterized in that it comprises: - walls (23.1-23.4) delimiting an internal cavity (21), - at least one of the walls (23.1) being a perforated wall having an internal face (30) turned towards the side of the internal cavity (21) inaccessible by a machining tool and an external face (31) turned towards the outside of the internal cavity (21), - the perforated wall (23.1) comprising a through ventilation opening (34) extending from the external face (31) to the internal face (30), - a chamfer (35) being provided on the side of one end of the through ventilation opening (34) opening into the internal cavity (21) on the side of the internal face (30) of the wall to be perforated (23.1).

8. Part according to claim 7, characterized in that it has a fillet (39) at the level of an interface between the chamfer (35) and the inner face (30) of the wall to be drilled (23.1).

9. Part according to claim 7 or 8, characterized in that two faces of a conical shape of the chamfer (35) seen in section have an angle greater than 40 degrees with respect to a horizontal plane.

10. Part according to any one of claims 7 to 9, characterized in that it further comprises a second chamfer (36) on the side of one end of the through ventilation opening (34) leading outwards from the internal cavity (21).

11. Part according to any one of claims 7 to 10, characterized in that it comprises a plurality of internal cavities (21) and corresponding through ventilation openings (34).

12. Part according to any one of claims 7 to 11, characterized in that it is made of a metallic material.