Device for surfacing a metal alloy part

Abstract

A device for surfacing a metal alloy part by laser welding, the part including a recess to be surfaced and located at a planar area of the part, the device including first and second protective elements arranged on either side of the recess, the first and second protective elements each having an irradiation surface which is to be at least partially covered with a layer of powder to enable welding by passing a laser beam over the powder, the laser beam passing over the irradiation surface of the first protective element during welding and then the irradiation surface of the second protective element, the second protective element having a shape for containing a layer of powder having a height that is greater at the end, in the direction of propagation of the laser beam during welding, of the second protective element than at the start of the second protective element.

Claims

1. A device for surfacing of a metal alloy part by laser welding, said part comprising a recess to be surfaced, said recess being located at an overall planar area of the part, the surfacing device comprising a first protective element and a second protective element, the first protective element and the second protective element being arranged on either side of the recess, the first protective element and the second protective element each having an exposure surface which is to be at least partially covered with a layer of powder in order to enable welding by passing a laser beam over said layer of powder, the laser beam passing over the exposure surface of the first protective element during welding and then the exposure surface of the second protective element, the second protective element having a shape capable of containing a layer of powder having a height that is greater at an end, in a direction of propagation of the laser beam during welding, of the second protective element than a height at a start of the second protective element, the second protective element having a first inclined side wall, a second inclined side wall parallel to the first inclined side wall, the height of the first inclined side wall and of the second inclined side wall increasing in the direction of propagation of the laser beam, wherein the first and second inclined side walls define between them an internal volume of the second protective element for containing the layer of powder.

2. The device according to claim 1, wherein each inclined side wall of the second protective element has an inclined notch suitable for receiving a plate, said plate having a face which makes up the exposure surface of the second protective element which is to be covered by the layer of powder.

3. The device according to claim 2, wherein the plate has an angle of inclination between fifteen degrees and twenty degrees relative to a plane of the globally planar zone exhibiting the recess.

4. The device according to claim 2, wherein the inclined side walls of the second protective element have a height at least one centimeter greater than a height of the plate.

5. The device according to claim 1, wherein each inclined side wall of the second protective element is extended by a flat foot which rests during laser welding on the metal alloy part, with one free end of each of said feet resting against the first protective element.

6. The device according to claim 5, wherein the flat feet have a thickness of between 0.5 millimeters and 1 millimeter.

7. The device according to claim 1, wherein the second protective element is placed against a positioning spacer held on the part comprising the recess to be surfaced.

8. The device according to claim 1, wherein the first protective element and the second protective element are made from an alloy of a same nature as the material to be surfaced.

9. The device according to claim 6, wherein the flat feet have a thickness of between 0.7 millimeters and 0.8 millimeter.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) The figures are only given for indication purposes and are in no way intended to limit the invention:

(2) FIG. 1, already described, schematically shows in section an example of a part to be resurfaced;

(3) FIGS. 2 to 4, also already described, schematically show various steps of an example of a state of the art process for surfacing of a part made of alloy;

(4) FIG. 5, also already described, shows a schematic representation of a device suitable to be used in an example of a state of the art method for surfacing of an alloy part;

(5) FIG. 6 shows an example of a device according to the invention for surfacing of a metal alloy part.

DETAILED DESCRIPTION OF AT LEAST ONE EMBODIMENT OF THE INVENTION

(6) Unless otherwise stated, the elements that appear in the various figures retain the same reference.

(7) In FIG. 6, the same elements can be seen as those in FIG. 5, except for the second cover 52 which is replaced by a second protective element 61, the first protective element being formed by the cover 51.

(8) According to the invention, the first protective element 51 and the second protective element 61 are arranged on either side of the recess 3; the second protective element has the shape of a ramp, and hereafter will be thus designated—that is to say, that it is formed by half of a rectangular parallelepiped; it thus has a first inclined side wall 62, a second inclined side wall 63 parallel to the first inclined side wall 62, with the height of the first inclined side wall 62 and of the second inclined side wall 63 increasing in the direction 53 of propagation of the laser beam. The ramp 61 in addition exhibits a closure wall 70 which serves to support the inclined side walls 62 and 63.

(9) Thus an internal volume 69 of the ramp 61 can be filled with powder so that it can subsequently be passed under the laser. By filling the internal volume 69 with powder, and by passing the laser over the powder thus deposited, only the surface layer of the powder is fused; thus the significant source of heat is progressively moved away from the part 1, and the risk of cracks appearing at the end of the beads is thus removed.

(10) In order to minimise the amount of powder consumed, it is proposed to insert a plate 64, itself inclined once positioned into the notches 65 and 66, into a first notch 65 and into a second notch 66, made respectively in the first inclined side wall 62 and in the second inclined side wall 64, in order to make an angle relative to the part 1 of between 15 and 20 degrees. An entire volume 74 located beneath the plate 64 thus remains empty, since it not filled with powder, which represents substantial savings in terms of the amount of powder consumed. Advantageously, it is envisaged that at least one centimeter is left between the top of the inclined side walls 62 and 63 and the plate 64, in order to have a sufficient thickness of powder available to preserve the plate 64 during fusion of the powder, since only a surface layer of the powder undergoes fusion.

(11) In the example described, each inclined side wall 62 and 63 of the ramp 61 is extended by a flat foot 67 and 68, which rests during laser welding on the metal alloy part 1, with one free end 71 and 72 of each of said feet and 68 resting against the first protective element 51. The flat feet 67 and 68 advantageously have a thickness of between 0.5 millimeters and 1 millimeter, notably a thickness of between 0.7 millimeters and 0.8 millimeters, which corresponds to the thickness of the powder to be spread before the laser beam is passed.

(12) The protective elements 51 and 61 are removable. Once a pass of the laser beam is completed, they may be removed in order to clean the part, in particular of remaining powder. The ramp 61 may then, if a second pass of the laser beam is necessary, be easily replaced onto part 1 by positioning it against a positioning spacer 73 which is held on the part 1 by any fastening means.

(13) Thus thanks to the device according to the invention, an effective method for surfacing using welding can be implemented, where the liquid pool produced during the passage of the laser beam is at a distance from the part to be surfaced. Any cracks are then generated in the excess thickness of powder located on the ramp 61, outside the part 1; the powder fused on the ramp is then easily eliminated during a machining operation.