Device for fabricating annular pieces by selectively melting powder, the device including a powder wiper

Abstract

A device fabricates annular pieces by selectively melting powder. The device includes an inner annular wall and an outer annular wall that are concentric and that define an annular powder deposition zone, and a powder dispenser movable in rotation about an axis of the inner and outer annular walls. The powder dispenser includes a wiper extending between the inner annular wall and the outer annular wall and forming an angle with the radial direction of the inner and outer annular walls.

Claims

1. A device for fabricating annular pieces by selectively melting powder, the device comprising: an inner annular wall and an outer annular wall that are concentric and that define an annular powder deposition zone, the inner annular wall and the outer annular wall have an axis, and a powder dispenser movable in rotation about the axis of the inner and outer annular walls, wherein the powder dispenser includes a wiper extending between the inner annular wall and the outer annular wall, the wiper forming an angle with the radial direction of the inner and outer annular wall, wherein the powder dispenser includes a powder dispenser orifice extending between the inner annular wall and the outer annular wall, the powder dispenser orifice forming an angle with the radial direction of the inner and outer annular walls, and wherein the powder dispenser orifice extends inside of the inner annular wall and outside of the outer annular wall.

2. The device according to claim 1, wherein the angle between the wiper and the radial direction of the walls is strictly greater than 0 and less than or equal to 30.

3. The device according to claim 1, wherein the wiper comprises at least two blades, namely a roughing blade and a finishing blade.

4. The device according to claim 1, wherein the angle between the powder dispenser orifice and the radial direction of the walls is strictly greater than 0 and less than or equal to 30.

5. The device according to claim 1, wherein the powder dispenser orifice has a section, and the section of the powder dispenser orifice increases in the radial direction.

6. The device according to claim 1, wherein the powder dispenser includes a powder tank.

7. The device according to claim 1, including an inner gutter and an outer gutter for recovering powder, the inner gutter and the outer gutter being arranged outside of the annular powder deposition zone, the inner gutter being arranged in a neighborhood of the distal end of the inner annular wall, while the outer gutter is arranged in a neighborhood of the distal end of the outer annular wall.

8. The device according to claim 7, including a powder suction and recycling system configured to suck up powder recovered in the inner and outer gutters and to convey the powder recovered to a powder tank.

9. The device according to claim 1, further comprising a tray positioned within distal ends of the inner and outer annular walls, the tray being mounted on a support to be slidable in a direction parallel to the axis of the inner and outer annular walls.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention and its advantages can be better understood on reading the following detailed description of various embodiments of the invention given as nonlimiting examples. The description makes reference to the accompanying sheets of figures, in which:

(2) FIG. 1 shows a device for fabricating annular pieces by selective melting of powder, as seen from above;

(3) FIG. 2 shows the FIG. 1 device, seen in section on plane II of FIG. 1;

(4) FIG. 3 shows the powder dispenser as seen in section on plane III of FIG. 2; and

(5) FIG. 4 shows the powder dispenser seen looking along arrow IV of FIG. 3.

DETAILED DESCRIPTION OF EMBODIMENTS

(6) FIGS. 1 and 2 show a device 10 for fabricating annular pieces by selective melting of powder. Naturally, and as a general rule, the powder is a metal powder that is sintered by one or more laser heads or by electron beam(s). There is thus alternation between depositing a layer of powder, and then selectively sintering the layer of powder by means of a laser head or an electron beam. This is known to the person skilled in the art, and is therefore not described in the present disclosure.

(7) The device 10 has an inner annular wall 12 and an outer annular wall 14 defining an annular zone A for depositing powder. The walls 12 and 14 are concentric, having a common axis X defining an axial direction X. The radial and azimuth directions are represented respectively by arrows R and Z. As shown in FIG. 2, the walls 12 and 14 are mounted to be stationary relative to a base 50, and a tray 52 that is mounted on a support 54, that is slidable in the axial direction X, and that forms a bottom, is arranged in the annular zone A. Thus, at the beginning of operations, the tray 52 is positioned so as to be set back a little from the distal ends 12A and 14A of the walls 12 and 14, and a first layer of powder is deposited and then sintered. Thereafter, the support 54 is moved downwards in FIG. 2, in such a manner that the tray 52 moves away from the ends 12A and 14A of the walls 12 and 14, thereby creating a new space for receiving a new layer of powder. Thereafter, a new layer of powder is deposited and then sintered, and the table is moved down again, etc. In FIG. 2, there can be seen an intermediate step while a piece 70 is being fabricated with a layer 80 of powder being deposited. It should be observed that the residual powder (i.e. the non-sintered powder) is held captive between the piece 70 being fabricated and the walls 12 and 14. For clarity of the description, the piece 70 in this example is an annular cylinder, however any other shape, and in particular a complex shape could naturally be envisaged, such as for example a bladed rotor wheel or a set of guide vanes.

(8) A powder dispenser 16 is movable in rotation about the axis X, and in this example it is mounted at the end of an arm 19. As can be seen in FIG. 3, the dispenser 16 comprises a wiper 18 and a tank 20 of powder.

(9) In FIG. 1, the wiper 18 is drawn as a discontinuous line. The angle between the wiper 18 and the radial direction R (with the arm 16 extending along the radial direction) is equal to 10 (ten degrees of angle).

(10) In this example, and with reference to FIG. 3, the wiper 18 comprises two parallel blades, namely a roughing blade 18A and a finishing blade 18B. The distal end of the roughing blade 18A is set back relative to the distal end of the finishing blade 18B. In this example, the setback T is equal to 0.02 mm. In general manner, the setback T lies in the range 0.01 mm to 0.04 mm.

(11) The powder tank 20 has a powder dispenser orifice 22. This orifice 22 is shown in FIG. 4 and extends between the inner wall 12 and the outer wall 14, from the inner wall 12 as far as the outer wall 14. In other words, in this example, the orifice 22 presents a first radial end arranged substantially facing the inner wall 12 in the axial direction X, and a second radial end arranged substantially facing the outer wall 14 in the axial direction X. The section S of the orifice 22 increases in the radial direction R. Specifically, in this example, the shape of the orifice is trapezoidal, the small side of the trapezoid being arranged on the inside, while the long side is arranged on the outside.

(12) The wiper 18 is mounted on a wall of the tank 20 in such a manner that the orifice 22 forms the same angle with the radial direction as does the wiper 18. It should be observed that in the meaning of the present invention, the angle between the wiper 18 and the orifice 22 is measured between the roughing blade 18A (if the wiper has a plurality of blades) and the wall defining the orifice 22 that is adjacent to the wiper 18.

(13) In FIG. 3, the orifice 22 is closed by a closure blade 24, this blade 24 moving into the opening position by bearing against the opening adjustment blade 26. Thus, the closure blade 24 is movable between a closed position shown in FIG. 3 and an open position corresponding substantially to the position of the blade 26.

(14) With reference to FIG. 2, the device 10 is fitted with an internal gutter 28 and with an external gutter 30, these gutters being arranged outside the annular zone A, and being connected to the distal ends 12A and 14A of the walls 12 and 14. These gutters 28 and 30 are not shown in FIG. 1, but they naturally extend over the entire inner periphery of the inner wall 12 and over the entire outer periphery of the outer wall 14. Suction nozzles 32 forming a suction and recycling system are arranged facing the bottoms of the gutters 28 and 30. These nozzles are configured to suck up the powder removed by the wiper 18 from the annular zone A. The powder as sucked up in this way is taken to a main powder tank 40 subsequent re-use. In this example, the nozzles 32 are secured to the arm 19 (coupling not shown) and they are driven in rotation together with the arm 19. In a variant, the gutters are also secured to the arm 19 and driven in rotation together with the arm. Under such circumstances, the gutters naturally do not extend over the entire azimuth lengths of the walls 12 and 14.

(15) In operation, and as shown in FIG. 2, the wiper 18, and more particularly the finishing blade 18B, is in contact in the axial direction X with the distal ends 12A and 14A of the walls 12 and 14. With the dispenser 16 being driven in azimuth Z in the direction Q as shown in FIGS. 1, 3, and 4, the wiper 18 removes surplus powder that is removed into the gutters 28 and 30 and subsequently sucked up and taken to the tank 40. For example, the nozzles 32 suck continuously while the wiper 18 is passing over the powder layer, such that the powder is sucked up as soon as it is removed into the gutters, thereby minimizing the undesirable presence of powder in the neighborhood of the annular zone A.

(16) Furthermore, and as shown in FIG. 4, the powder dispenser orifice extends a little beyond the inner and outer walls 12 and 14. The gutters 28 and 30 also serve to recover and recycle this powder surplus that is deposited outside the annular zone while powder is being dispensed.

(17) Naturally, since the wiper 18 is fastened to the tank 20, powder is removed by the wiper 18 at the same time as powder deposition is taking place. Nevertheless, since the orifice 22 can be closed, it is possible, after the first revolution, to continue the stroke of the wiper 18 while the orifice 22 is closed, e.g. over one fourth of a revolution, in order to ensure proper removal of the powder surplus.

(18) Although the present invention is described with reference to specific embodiments, it is clear that modifications and changes may be made to those embodiments without going beyond the general ambit of the invention as defined by the claims. In particular, individual characteristics of the various embodiments that are illustrated and/or mentioned may be combined in additional embodiments. Consequently, the description and the drawings should be considered in a sense that is illustrative rather than restrictive.

(19) It is also clear that all of the characteristics described with reference to a method may be transposed, singly or in combination, to a device, and conversely all of the characteristics described with reference to a device may be transposed, singly or in combination, to a method.