Device and method for repairing a degraded area of ​​a friction stir welded surface

Abstract

This device (14) for repairing a damaged area of ​​a friction stir welded surface (10) comprises a fastening means (24) for passing through the surface (10) at the location of the damaged area (12), an adapter ring (26) for the fastening means (24), and a ring (28) for encircling the fastening means (24) and bearing against the surface (10). Figure for the abbreviation: Fig 3

Description

Description Title of the invention: Device and method for repairing an area degradation of a surface welded by friction mixing technical field

[0001] — The present invention relates to friction mixing assembly methods, also called "friction stir welding" in Anglo-Saxon terms.

[0002] — In particular, the present invention relates to the reworking of surfaces assembled by friction mixing, particularly after the removal of a pin enabling mixing.

[0003] In general, the invention applies to any type of field requiring an as- assembly by friction mixing of two elements to be assembled. Previous techniques

[0004] In industry, and particularly in the aeronautical industry, it is common to have to To assemble several elements together. This could be, for example, the assembly of a stiffener on a structural panel of an aircraft in order to stiffen said panel of structure.

[0005] — Among the various assembly methods, manual riveting is the most common. However, riveting involves long assembly times due to its manual character.

[0006] — Friction stir welding is a faster assembly process and allowing it to be automated. It allows, using a rotating pawl of less than 10 millimeters in diameter, to mix together the materials of the elements to be assembled and This creates a weld. Mixing is particularly suitable for alloys. aluminum.

[0007] — A schematic representation of an implementation method is shown in [Fig.1] Friction stir welding process in a lap configuration. [Fig. 1] illustrates a cross-sectional view of the assembly of a structural panel 2 with a stiffener 4, structural panel 2 and stiffener 4 each measuring a few millimeters thicknesses in millimeters, for example each measuring 2 millimeters thick. For the Implementation of friction stir welding, a welding pin 6 moves against stiffener 4 while being held in rotation. Pin 6 thus kneads and mixes the materials of the stiffener 4 and the structural panel 2 in such a way as to create a bead welding 8 assembling the two elements.

[0008] — However, the cessation of the friction kneading process, and in particular the withdrawal of the pin 6 leaves an area of ​​highly degraded material on the surface of the stiffener.

[0009] = A schematic cross-sectional view of surface 10 is shown in [Fig.2] of a stiffener 4 after the removal of the pin 6 from friction stir welding. The surface 10 presents a zone 12 of highly degraded material at the location of the pin 6 withdrawal. This zone 12 concentrates mechanical stresses, is unsightly and is a zone of retention of liquid and residues which can deteriorate the corrosion resistance of the zone. Description of the invention The present invention therefore aims to overcome the aforementioned drawbacks and to provide a device and method for repairing a degraded area that is simple and quick to implement. The present invention relates to a device for repairing a degraded area of ​​a surface welded by friction stir, the device comprising a fastening means intended to pass through the surface at the location of the degraded area, an adapter ring for the fastening means, and a ring intended to encircle the fastening means and to bear against the surface. Thus, the degraded area is replaced by a non-abrasive device that does not risk tearing off an element passing nearby, the device respecting the mechanical constraints imposed by the thinness of the elements assembled by friction mixing. In one embodiment, the fastening means includes a rivet and the ring includes a counter-rivet washer. Advantageously, the fastening means includes an annular bead for retaining the ring's band. Advantageously, the ring comprises a length of less than 10 millimeters, preferably less than 5 millimeters, a minimum external diameter of between 5 and 15 millimeters, and a countersunk head comprising a maximum external diameter of dimensions between 0.1 millimeters and 4 millimeters greater than the minimum external diameter of the ring. In one embodiment, the fastening means includes a thread and the ring includes a thread. Advantageously, the fastening means comprises titanium and / or steel, the ring comprises stainless steel and the band comprises stainless steel. The present invention also relates to an aircraft comprising a device for repairing a degraded area of ​​a surface welded by friction stir welding as defined above. The present invention relates to a method for repairing a degraded area of ​​a friction stir welded surface comprising the following steps: - Drilling a hole through the surface at the location of the damaged area; and - Installation of a ring, a means of fastening and a ring of the device as defined above and / or of the aircraft as defined above so as to obstruct the drilled orifice. Brief description of the drawings Other objects, features and advantages of the invention will become apparent from the following description, given solely by way of non-limiting example, and made with reference to the accompanying drawings in which: [Fig.1] which has already been mentioned is a schematic cross-sectional view of a stiffener and a structural panel assembled by a friction stir welding process; [Fig.2] which has already been mentioned is a schematic cross-sectional view of a stiffener and a structural panel assembled by a friction stir welding process after the removal of the welding pin; [Fig.3] is a schematic cross-sectional view of a device for repairing a degraded area of ​​a friction stir welded surface according to the invention and installed between a structural panel and a stiffener; [Fig. 4] is a flowchart schematically illustrating the steps of a process for repairing a degraded area of ​​a friction stir welded surface according to the invention; and [Fig.5] is a variant of the schematic cross-sectional view of [Fig.3] illustrating a device for repairing a degraded area of ​​a friction stir welded surface according to the invention. Detailed description of at least one embodiment A schematic cross-sectional view of a device 14 for repairing a degraded area 12 of a surface 10 welded by friction stir welding has been schematically represented in [Fig.3], the degraded area 12 being similar to the area illustrated in [Fig.2] previously mentioned. Device 14 is intended to be used during a repair process of the degraded area, the degraded area 12 having appeared upon removal of the welding pin 6. The steps of this process are schematically represented in [Fig. 4]. This process is applicable to any assembly of elements carried out using friction stir welding. In particular, and as illustrated in Figures 1 to 3, the assembled elements are, for example, a structural panel 2 and a stiffener 4, each being quite thin, on the order of 2 millimeters thick. The structural panel 2 and the stiffener 4 are, for example, made of aluminum alloy. Initially, a step 16 is performed by drilling a hole 18 through the surface 10 at the location of the degraded area 12. The resulting hole 18 thus passes through the structural panel 2 and the stiffener 4 along an axis A and eliminates the The deformed material of the damaged area 12. The drilled hole 18 has a diameter 20 approximately equal to the diameter of the damaged area 12, or approximately equal to the diameter of the welding pin 6. For example, the hole 18 has a diameter 20 of approximately 10 millimeters. It is then necessary to block the orifice 18 in order to ensure the sealing of the structural panel 2 and the stiffener 4 against the fluid flows present on one side and / or the other of the orifice. We therefore carry out a step 22 of installing the repair device 14 in the orifice 18 so as to obstruct said pierced orifice 18. The device 14 for repairing the degraded area 12 includes a fastening means 24, a ring 26 and a ring 28. The fastening means 24 is designed to pass through the opening 18 and the surface 10 at the location of the damaged area 12. The fastening means 24 comprises, for example, a conventional rivet. The fastening means 24 is straight and includes a flared head 30. In one embodiment, the fastening means 24 includes an annular bead 32 facilitating the retention of the fastening means 24 by the ring 28. The fastening means 24 includes, for example, a hard material such as steel and / or titanium. The diameter of the fastening means is less than the diameter 20 of the orifice 18. Due to the thinness of the structural panel 2 and the stiffener 4, and due to the large width of the diameter 20 of the orifice, there is no means of fixing or adapter ring on the market capable of directly obstructing the orifice 18. The ring 26 makes it possible to overcome this lack. Ring 26 is an adapter ring for the fastening means 24 to the orifice 18. The internal diameter of the adapter ring is therefore the same as the diameter of the fastening means 24. The ring 26 has a length equal to or slightly greater than the length of the orifice along axis A. The length of the ring is less than 10 millimeters and preferably between 4 and 5 millimeters. The ring 26 has a minimum external diameter equivalent to the diameter 20 of the orifice 18. Depending on the orifice 18, the ring has a minimum external diameter between 5 and 15 millimeters. The ring 26 includes a countersunk head 34 that flares outwards and whose maximum external diameter 36 is slightly larger than its minimum external diameter 20. For example, the maximum external diameter 36 is 0.1 to 4 millimeters larger than the minimum external diameter 20, preferably 1 to 3 millimeters larger. The dimensions of the countersunk head 34 allow the mechanical stresses induced by the short length of the orifice 18 and its large diameter 20 to be met, unlike commercially available countersunk rings, whose diameter The maximum external diameter is greater than the minimum external diameter. Ring 26, for example, is made of a material including stainless steel. The ring 28 is intended to encircle the fastening means 24 and bear against the surface 10. In particular, the ring 28 may include a counter-rivet 28 that is totally or partially annular, ensuring the sealing of the device 14 when the device 14 is placed in the orifice 18. For example, the ring 28 includes on its perimeter a rim 38 that comes into contact with the surface 10 so that the ring 28 is slightly raised to allow the ring 26 to protrude from the surface 10. Ring 28, for example, is made of a material including stainless steel. The annular bead 32 is in contact with the ring 28 and allows the ring 26 to be held around the fastening means 24 and allows the device 14 to be locked in position in the orifice 18. Figure 5 shows a second embodiment of the device 14 for repairing a degraded area 12 of a surface 10 welded by friction mixing. In this embodiment, the device 14 is similar to the device 14 of [Fig. 3]. However, alternatively, the device 14 includes a threaded nut 40, and the fastening means 24 does not include an annular bead 32, but rather a thread in place of the annular bead 32, the thread being intended to cooperate with the nut 40. The screwed nut 40 bears against the ring 28 and thus locks the device 14 to ensure the obstruction of the orifice 18.

Claims

Demands

1. Device (14) for repairing a degraded area (12) of a surface (10) welded by friction stir, characterized in that it comprises a fastening means (24) intended to pass through the surface (10) at the location of the degraded area (12), an adapter ring (26) of the fastening means (24), and a ring (28) for encircling the fastening means fixing (24) and to rest on the surface (10).

2. Device according to claim 1, wherein the fastening means (24) includes a rivet and the ring (28) includes a washer counter-rivet.

3. A device according to any one of claims 1 and 2, wherein the means of fastening (24) includes an annular bead (32) for retaining the ring girdling (28).

4. Device according to any one of claims 1 to 3, in which the ring (26) comprises a length of less than 10 millimeters, of preferably less than 5 millimeters, a minimum external diameter (20) between 5 and 15 millimeters, and a countersunk head (34) comprising a maximum external diameter (36) with dimensions between 0.1 mil- 10 meters and 4 millimeters greater than the minimum external diameter of the ring (26).

5. Device according to any one of claims 1 to 4, in which the fastening means (24) includes a thread and the ring (28) includes a thread.

6. Device according to any one of claims 1 to 5, in which the fastening means (24) comprises titanium and / or steel, the ring (26) comprises stainless steel and the ring (28) comprises stainless steel.

7. Aircraft characterized in that it comprises a re- device (14) repair of a degraded area (12) of a surface (10) welded by friction mixing according to any one of claims 1 to 6.

8. Method for repairing a degraded area (12) of a surface (10) welded by friction stir, characterized in that it comprises the Next steps: Drilling (step 16) a hole (18) through the surface (10) at the location of the degraded area (12); and Installation (step 22) of a ring (26), of a means of fastening (24) and a ring (28) of the device (14) according to one any of claims 1 to 6 and / or of the aircraft according to claim 7 so as to obstruct the drilled orifice (18).