This application is the U.S. National Stage of PCT/FR2013/051016, filed May 7, 2013, which in turn claims priority to French Patent Application No. 1254191, filed May 9, 2012, the entire contents of all applications are incorporated herein by reference in their entireties.
The invention relates to a method for hard-surfacing metal parts for aircraft turbofans. It also relates to a specific tool for locally protecting metal parts to be hard-surfaced by the method according to the invention.
Therefore, the technical field of the invention generally relates to the field of aircraft engines, and more particularly the field of repair by a method for hard-surfacing some metal parts of aircraft engines.
Without being limiting, the considered metal part is advantageously, for example, a vane of a one-piece bladed disk, or even any part having a trailing edge and/or a leading edge, for example blades of a low pressure turbine. In practice, the invention relates to any metal part of an aircraft turbofan having a portion, especially an end, requiring a hard-surfacing operation, that is an operation of repair by restoring an appropriate shape of the considered part, by a TIP repair type method. The TIP repair type methods use a method for spraying a directed laser (or a directed electron beam), operating a selective powder melting (the method is especially referred to by “laser cladding”, or “laser metal deposition”), which enables, by successively passing a laser on a powder deposit, the considered part to be restored.
The metal parts which are advantageously concerned by the invention are those having an oxidation risk during the hard-surfacing operation. This is the case for metal parts comprising titanium, but also nickel, aluminium or even cobalt. For such parts, it is actually necessary, in order to prevent any degradation of the mechanical characteristics of the considered part, to prevent any oxidation of said part.
In the state of the art, several solutions have been provided to conduct such operations of laser hard-surfacing in order to repair some metal parts. The use of large sized chambers has especially been provided, creating a gap either filled with neutral gas, or which was vacuumed, in which are fed the part to be hard-surfaced and all the equipment involved for the hard-surfacing; but such a solution is expensive, and its implementation is slow, because of the large amounts of inert gases fed into the considered chamber. Another solution provided in the state of the art is illustrated in
In the method of the state of the art illustrated in
However, such a method is not satisfactory to hard-surface the end 102 over a significant distance of a few centimetres. Yet, the end 102 of the vane 101 is curved, and the translational movement to which the nozzle 103 is limited prevents the protection enclosure from moving over this significant distance. Indeed, the notch 105, in order to be able to fulfil its filling with a neutral gas, and so that the protection enclosure 104 can be inserted between the vane 101 and the neighbouring vanes—not shown—must have a limiting dimension. Such a limitation of these dimensions results in the notch 105 walls being close to each other, and rapidly contacting the end 102, consequently preventing the possibility of hard-surfacing over the whole end 102 to be hard-surfaced.
The object of the invention offers a solution to the issues just explained, by providing a method and a tool, which are inexpensive, for locally protecting the hard-surfacing of metal parts which allows a large translational movement of the nozzle in order to be able to reach the entire area to be hard-surfaced, said tool being not too bulky in order not to be hindered by the presence of neighbouring parts, for example vanes. To this end, the protection enclosure is provided to be made non-integral with the nozzle emitting the laser beam. In order to restrict the losses of neutral gases fed into the enclosure, an enclosure top closing means is also provided, said closing means not hindering the movement of the nozzle, and ensuring a sufficient insulation in order for the presence of a neutral gas to effectively prevent the oxidation of the part during hard-surfacing; the ensured insulation prevents the neutral gas from escaping too rapidly from the enclosure and being replaced therein by ambient oxygen, and the described oxidation phenomenon from being caused.
Therefore, in the invention, in order to avoid using a whole chamber, comprising the part to be hard-surfaced and the equipment supporting the nozzle, under a neutral gas, a local protection tool mounted on the vane to be hard-surfaced is used. This tool enables an inert area all around the part, and any oxidation to be prevented during the hard-surfacing.
To this tool is coupled a mobile cover closely fitting the shape of the tool throughout the hard-surfacing which is put into movement by the nozzle for gas spraying.
Thus, the invention essentially relates to a method for hard-surfacing metal parts for an aircraft turbofan, said method involving the use of a nozzle emitting a laser beam, or an electron beam, which is to heat a powder sprayed on the part for hard-surfacing said metal part, characterised in that said method comprises the various following steps:
Besides the main characteristics just mentioned in the preceding paragraph, the method according to the invention can have one or more additional characteristics among the following, taken into consideration individually or according to the technically possible combinations:
The present invention also relates to a tool, able to implement the method according to the invention, for hard-surfacing metal parts for an aircraft turbofan, said hard-surfacing being carried out by means of a laser, generated by a nozzle, heating a powder for hard-surfacing said metal part, characterised in that said tool comprises:
Besides the main characteristics just mentioned in the preceding paragraph, the tool according to the invention can have one or more additional characteristics among the following, taken into consideration individually or according to the technically possible combinations:
The invention and its various applications will be better understood upon reading the following description and upon examining the accompanying figures.
The figures are only presented by way of indication and not limitation at all of the invention.
The figures show:
in
in
in
in
in
The tool 200 here comprises:
According to the method according to the invention, once the tool 200 is positioned and the vane 301 is introduced in the enclosure 201, the nozzle 103 is brought to the level of the opening 222 of the mobile cover 221. As can be seen in
As can be seen in
Number | Date | Country | Kind |
---|---|---|---|
1254191 | May 2012 | FR | national |
Filing Document | Filing Date | Country | Kind |
---|---|---|---|
PCT/FR2013/051016 | 5/7/2013 | WO | 00 |
Publishing Document | Publishing Date | Country | Kind |
---|---|---|---|
WO2013/167841 | 11/14/2013 | WO | A |
Number | Name | Date | Kind |
---|---|---|---|
5262612 | Momany | Nov 1993 | A |
6326585 | Aleshin | Dec 2001 | B1 |
7939003 | Bonassar | May 2011 | B2 |
8053701 | Will | Nov 2011 | B2 |
20110217457 | Huttner et al. | Sep 2011 | A1 |
Number | Date | Country |
---|---|---|
86101259 | Dec 1986 | CN |
2346379 | Nov 1999 | CN |
Entry |
---|
Machine Translation of Hirokazu et al (CN86101259); Apr. 2020. |
International Search Report issued in International Application No. PCT/FR2013/051016, dated Aug. 7, 2013. |
Number | Date | Country | |
---|---|---|---|
20150114938 A1 | Apr 2015 | US |