Process and tooling for manufacturing a part by welding

Abstract

Method for welding a first part and a second part both made of metallic material, comprising the steps of: positioning on an anvil a first edge of the first part and a second edge of the second part in such a way that the second edge adjoins the first edge, defining a joining line; applying a rotating tool to the edges to form a friction stir weld along the joining line. The anvil is provided along the joining line with a martyr piece fixed to the anvil in a removable manner. Tooling for implementing this method. FIGURE OF THE ABSTRACT: Fig. 1

Description

Title of the invention: Method and tool for manufacturing a part by welding

[0001] The present invention relates to the field of welding, and more particularly to friction stir welding.

[0002] BACKGROUND OF THE INVENTION

[0003] It is known to manufacture parts by welding parts of parts. A welding process currently used is friction stir welding. Friction welding or friction stir welding or FSW (from the English friction stir welding) consists of heating two parts of a part by friction to bring them locally to a pasty state allowing a weld to be made between these two parts of the part.

[0004] Friction stir welding is most commonly used for butt welding operations. Butt welding means the creation of a weld between a first edge of a first part of a part and a second edge of a second part of the part; the first edge extending parallel to the first edge and opposite the second edge. The weld may be a weld with straight edges, a V-weld (the edges are chamfered over their entire height), a Y-weld (the edges are chamfered over part of their height), a U-weld (the edges are hollowed out to form a groove once joined together)...

[0005] A welding tool comprising a projecting shoulder from which a profiled pin extends is rotated and applied to the area to be welded (the shoulder bears against the surface of the parts of the part directly above the two edges and the pin penetrates between the two edges) to heat the two edges by friction until they are brought into a pasty state kneaded by the tool to carry out the welding at a temperature below the melting temperature of the material.

[0006] One of the difficulties in implementing friction stir welding lies in controlling the surface condition at the rear of the weld, particularly for hollow parts. Another of these difficulties is to take up the penetration force exerted on the parts of the parts by the tool parallel to its axis of rotation.

[0007] SUBJECT OF THE INVENTION

[0008] The invention aims in particular to facilitate friction stir welding. Summary of the invention

[0009] To this end, the invention provides a method for welding a first part and a second part, both made of metallic material, comprising the steps of: - position on an anvil a first edge of the first piece and a second edge of the second part such that the second edge adjoins the first edge defining a joining line; - applying a rotating welding tool (103) to the edges to form a friction stir weld along the junction line.

[0010] The anvil is provided along the junction line with at least one martyr piece fixed to the anvil in a removable manner.

[0011] Thus, the use of a martyr piece removably attached to the anvil has several advantages. It allows the welding forces to be taken up without hindering the subsequent removal of the welded piece from the anvil since, in the event of adhesion of the martyr piece to the weld, the martyr piece can be removed from the anvil at the same time as the welded piece before being detached from the weld. In the event of deterioration of the martyr piece, it is easy to replace it whereas in the absence of a martyr piece, deterioration of the anvil requires machining of the anvil. Finally, it allows control of the surface condition behind the weld.

[0012] The invention also relates to a tool for implementing this method.

[0013] The friction stir welding tool comprises an anvil provided with a martyr part, and a tool mounted opposite the martyr part to be movable in rotation and translation relative to the martyr part.

[0014] Other characteristics and advantages of the invention will emerge from reading the following description of particular and non-limiting embodiments of the invention. Brief description of the drawings

[0015] Reference will be made to the accompanying drawings, among which:

[0016] [Fig.l] [Fig.l] is a partial schematic view, in elevation, illustrating the process welding according to the invention;

[0017] [Fig.2] [Fig.2] is a partial top view illustrating this method;

[0018] [Fig.3] [Fig.3] is a sectional view of a welded part installed in the tooling before a welding operation. DETAILED DESCRIPTION OF THE INVENTION

[0019] The invention relates to the manufacture of a welded part generally designated P, such as a vehicle part (aircraft structural or landing part for example), by implementing a friction stir welding process.

[0020] According to a first embodiment, the welded part P is made from a first part part (or part) generally designated 1.1 and a second part part (or part) generally designated 1.2. The part parts 1.1 and 1.2, here an aluminum, both comprise two opposite main surfaces 2.1, 2.2 and 3.1, 3.2 joined by a side or edge 4.1, 4.2. The part parts 1.1 and 1.2 are here in two different grades of aluminum.

[0021] To produce the part P, the first part of part 1.1 and the second part of part 1.2 must be welded edge to edge along the edges 4.1, 4.2 forming a junction line LJ of the two parts of part 1.1, 1.2.

[0022] To carry out the butt welding, the parts of the part 1.1, 1.2 are placed in a tool, generally designated 100.

[0023] The tool 100 comprises a frame 101 carrying a welding head 102 which is driven in horizontal and vertical translation relative to the frame 101. A welding tool 103 is mounted on the welding head 102 to pivot about an axis of revolution of the welding tool 103 and is driven in rotation about this axis. The welding tool 103 comprises a projecting shoulder 104 from which a pin 105 extends. The welding tool 103 is driven in translation parallel to itself in a so-called feed movement to allow the production of a weld bead.

[0024] The welding tool 103 extends directly above an anvil 106 resting on the frame 101. The anvil 106 is provided with a martyr part 107, in the form of a tongue, removably fixed in a groove formed in an upper surface 108 of the anvil 106 in such a way that the martyr part 107 is flush with the upper surface 108. Within the meaning of the invention, the simple engagement of the martyr part 107 in the groove constitutes a removable fixing. Nevertheless, it is possible to provide additional fixing means such as axial stops or pins immobilizing the martyr part along the groove; an adhesive such as glue or double-sided tape... The martyr part 107 has a width l107 greater than or close to the diameter di04 of the shoulder 104 of the tool 103. The martyr part 107 has a length Li07 greater than a length Li of the junction line LJ of the parts 1.1 and 1.2 and here also of the anvil 106 in such a way that the martyred part 107 has at least one of these end portions 107.1, 107.2, here both, extending in projection from the parts 1.1, 1.2 and from the anvil 106. These projecting end portions facilitate the removal of the martyred part 107 from the anvil 106 for its replacement but also the detachment of the martyred part 107 from the welded part P if the martyred part 107 has adhered to the weld made as will be seen later.

[0025] The workpiece parts 1.1, 1.2 are clamped on the anvil 106: the workpiece parts 1.1, 1.2 rest by their surfaces 3.1, 3.2 on the surface 108 of the anvil 106 and the edges 4.1, 4.2 are arranged opposite each other in line with the martyr workpiece 107. The clamping of workpiece parts on an anvil is known in itself and will not be detailed here.

[0026] Friction stir welding begins by rotating the welding tool 103 and then applying it to the workpiece parts 1.1, 1.2 in such a way that the shoulder 104 bears against the surface 2.1, 2.2 of the workpiece parts 1.1, 1.2 near the two edges 4.1, 4.2 and the pin 105 penetrates between the two edges 4.1, 4.2 to heat the two edges 4.1, 4.2 by friction until they are brought into a pasty state kneaded by the rotating welding tool 103. The welding is thus carried out at a temperature lower than the melting temperature of the material. The welding tool 103 is then moved from one end to the other of the junction line LJ. The welding tool 103 and the control of its movements to carry out friction stir welding are known in themselves and will not be detailed further here.

[0027] Once the welding has been carried out, the welded part P is unclamped, removed from the anvil 106 and extracted from the tool 100.

[0028] The martyr piece 107 can be made of different materials.

[0029] According to a first embodiment, the martyr part 107 comprises at least in surface a material limiting the adhesion of the weld to the martyr part 107. More precisely, the martyr part 107 has an upper surface made of a material resistant to the heat released by welding and having anti-adhesion properties with respect to the material of the parts of the parts being welded. This material is here a composite material comprising ceramic reinforcing fillers embedded in a metal matrix (material called CERMET). The matrix is ​​here made of cobalt and the reinforcing fillers are made of tungsten carbide. The material takes the form of a coating covering the tab, for example made of steel. The deposition of the coating is here carried out by the high-speed oxygen fuel projection process or HVOF (High Velocity Oxygen Fuel). Other deposition methods are possible. Other composite materials of this type can be used or non-composite materials.The martyred part 107 may also comprise a surface layer of talc or a wax. In addition, the martyred part 107 may be entirely made of the material having the anti-adhesion properties with respect to the material of the parts of the parts being welded.

[0030] Thus, in this embodiment, the part P can be removed from the tooling without adhering to the martyr part 107 or to the anvil 106. At worst, if the martyr part 107 were damaged and adhered to the welded part P, it would be sufficient to exert a detachment force on the martyr part 107 by pulling on at least one of the ends 107.1, 107.2 of the martyr part 107 in a direction normal to the welded part P.

[0031] According to a second embodiment, the martyr part 107 is made of a material such that a transfer of said material to the weld does not cause any significant alteration of the properties of the weld.

[0032] The martyr part 107 is made here from the same material as the part parts 1.1, 1.2, namely here aluminum. Preferably, the aluminum used for the martyr part 7 is treated to exhibit a chromic anodic oxidation: such oxidation improves the corrosion resistance. Alternatively, the aluminum used for the martyr part 7 is treated to exhibit a sulfuric anodic oxidation: Such oxidation improves corrosion resistance but also wear resistance. Alternatively, the aluminum used for the martyr part 7 is treated by chromating to improve corrosion resistance.

[0033] Thus, not only is the martyred part 107 made of a material such that a transfer of said material to the weld does not cause a significant alteration in the property of the weld, but, in addition, the material of the martyred part 107 is capable of generating an improvement in at least one property of the weld in the event of transfer, for example here the resistance to corrosion or the adhesion of a subsequent coating on the weld.

[0034] It is noted that the martyr part 107 can be replaced by another if it is altered after a welding operation.

[0035] This embodiment also covers a martyr part in the form of a thin tab of pure aluminum which is diffusion welded to the part parts 1.1, 1.2. The martyr part thus locally forms an internal coating of the welding zone of the welded part. This produces a surface cladding of the entire welding zone.

[0036] After the welding operation, a finishing phase can be provided comprising all or part of the following steps (here all): - carry out heat treatment to obtain a metallurgical state suitable for subsequent use of the welded part P and to release the stresses linked to the welding; - abrade the surface of the welded part P at least in the vicinity of the weld; - brush the weld to reduce the ripples present on the surface ex interior of it and improve the fatigue resistance of the weld; - carry out non-destructive testing of the welded part P (for example by ultrasound, eddy current, penetrant testing or X-ray); - carry out finishing machining of the welded part P (including the start and end of welding zones); - deposit a coating on the weld or the entire welded part P.

[0037] The heat treatment is known in itself and aims to obtain a metallurgical state corresponding to current standards for the intended application.

[0038] The abrasion is carried out by milling and aims to remove localized excess material to obtain a smooth surface having a surface finish corresponding to current standards for the intended application. The abrasion can be carried out in several phases, for example a deburring or rough surfacing phase, and a fine surfacing phase.

[0039] Another example of a part welded using the method of the invention will be described here.

[0040] According to a second embodiment of the method of the invention, the welded part P' is a hollow part of rectangular section which comprises two first parts of parts 11.1, here connecting rod bodies, spaced by two parts of part 11.2, here plates.

[0041] Each part of the piece 11.2 is therefore a plate which comprises two main faces 12.2, 13.2 and has a substantially elongated trapezoidal shape with two longitudinal edges 14.2 converging from a first end of the plate towards a second end of the plate, the first end being wider than the second end.

[0042] Each part 11.1 is therefore a connecting rod body having a substantially parallelepiped shape and comprising a main projecting face from which extend two longitudinal tongues which are parallel to each other and which each have a free edge 14.1, an external surface 12.1 and an internal surface 13.1. Each tongue here has a thickness equal to the thickness of the plates. Each connecting rod body has two end sections parallel to each other and each provided with a bore with an axis perpendicular to the end sections; and the two end sections are slightly offset from each other in a direction parallel to the axes of the bores so that, when the two connecting rod bodies are placed face to face with their tongues facing each other, the connecting rod bodies converge towards each other in accordance with the convergence of the longitudinal edges 14.2.

[0043] To form the welded part P', the free edges 14.1 will be welded to the edges 14.2 so as to form the hollow rectangular cross-section of the welded part P'.

[0044] As previously, an anvil 106 is used whose height hi06 (measured perpendicular to the surface 108) is equal to the spacing between the second part parts 11.2 in the finished welded part P'. The anvil 106 is here provided with two martyr parts 107 flush with the same surface 108 of the anvil to carry out the welding of the two edges 14.2 of the part part 11.2 each to one of the edges 12.1 of one of the part parts 11.1 and to one of the edges 12.1 of the other of the part parts 11.1.

[0045] We start by welding, as previously described, the first two parts 11.1 to one of the second parts 11.2. We can raise the anvil 106 to ensure that the surfaces 13.1, 13.2 are supported on the anvil 106 and the martyr part 107.

[0046] The assembly thus formed is removed from the tooling, as is the anvil 106, then is turned over and placed again in the tooling. The anvil 106 is then placed between the two first part parts 11.1, on the already welded second part part 11.2, in such a way that each martyr part 107 extends partly under the surface 13.1 and the edge 14.1 of one of the first part parts 11.1. The second part of remaining part 11.2 is then placed on the anvil 106 with each edge 14.2 on one of the martyr parts 107 and welding is carried out.

[0047] At the end of welding, the anvil 106 is removed by sliding it along the welded part P'. If one of the martyr parts 107 adheres to the weld, the martyr part 107 will detach from the anvil 106 due to the tensile force exerted on the anvil 106 and will then be removed from the welded part P'.

[0048] Of course, the invention is not limited to the embodiments described but encompasses any variant falling within the scope of the invention as defined by the claims.

[0049] In particular, the method of the invention can be used to manufacture any type of part, for example an aircraft landing gear part, for example: a strut arm, a stabilizing rod, a bracing panel, a brake bar, a main box, etc.

[0050] The invention is applicable to parts made from materials other than aluminum and for example made from steel or titanium.

[0051] The parts may have other shapes than those shown.

[0052] One or more of the finishing steps may be omitted.

[0053] The parts of parts can be obtained by one or more operations of rolling, forging, die-stamping, or any other manufacturing operation, possibly followed by another operation such as a machining or re-machining operation.

[0054] The tooling may have a structure different from that described.

[0055] The welding head can be positioned at the end of a robot arm.

[0056] The anvil can be provided with several martyr pieces.

[0057] The martyr piece may have a length such that it extends beyond the parts of the pieces at at least one end of the joining line.

[0058] The martyred part can have a surface condition Ra of at most 1.6.

Claims

Claims

1. Method for welding a first part (1.1) and a second part (1.2) both made of metallic material, comprising the steps of: - positioning on an anvil (106) a first edge (4.1) of the first part and a second edge (4.2) of the second part in such a way that the second edge adjoins the first edge, defining a joining line (LJ); - applying to the edges a rotating welding tool (103) to form a friction stir weld along the joining line; the anvil being provided along the joining line with at least one martyr part (107) fixed to the anvil (106) in a removable manner; characterized in that the martyr part (107) is made of a material such that a transfer of said material to the weld does not cause a significant alteration in the property of the weld and the material of the martyr part (107) is capable of generating an improvement in at least one property of the weld in the event of transfer.

2. Method according to claim 1, in which the martyred part (107) comprises at least on the surface a material limiting the adhesion of the solder to the martyred part.

3. The method of claim 2, wherein the material comprises a wax or a composite material having a metal matrix and ceramic reinforcing fillers embedded in the matrix.

4. A method according to claim 1, wherein the material of the martyr part (107) is substantially identical to a material of the part portions (1.1, 1.2).

5. The method of claim 4, wherein the part portions are aluminum and the martyr part is type O AC, OAS or Surtec protected aluminum.

6. A method according to claim 1, wherein the martyr part (107) in the form of a thin tongue is welded to the part parts (1.1, 1.2) during friction stir welding in such a way that the martyr part forms a coating of the weld area.

7. A method according to any preceding claim, wherein the martyr part is replaced after one or more operations welding.

8. A method according to any preceding claim, wherein the welding is carried out by means of a tool having a projecting shoulder from which a pin extends, the shoulder being applied against the part parts during welding and the pin penetrating between the part parts, the martyr part having a tongue shape of width substantially equal to a diameter of the shoulder.

9. A method according to any preceding claim, wherein the martyr piece has a length such that it extends beyond the piece portions at at least one end of the joining line.

10. A method according to any preceding claim, wherein the martyred part has a surface finish Ra of at most 1.

6.

11. Friction stir welding tooling, comprising an anvil provided with a martyr part in accordance with the method according to any one of the preceding claims, and a tool mounted opposite the martyr part to be movable in rotation and translation relative to the martyr part.

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