Friction stir welding tool comprising a retractable guide member and a welding process

Abstract

A friction stir welding tool with a base, a rotating friction stir slug mounted in the said base and at least one guide member connected to the said base, the welding tool being adapted to move from upstream to downstream; a welding tool having at least one displacement member of the guide member relative to the said base between at least one guiding position in which the guide member extends in a scout area located downstream and facing the friction stir slug and at least one retracted position in which the guide member is offset from the said scout area.

Claims

1. A friction stir welding tool comprising: a base, a rotating friction stir slug mounted with said base and positionable in a welding position to weld an interface line of a first surface and a second surface, an upstream guide member connected to said base, and a downstream guide member connected to said base, and wherein the welding tool is movable from an upstream location to a downstream location when moving along a surface to be welded; a displacement member coupled to the downstream guide member, the displacement member comprising a hydraulic cylinder comprising a barrel secured to the base, a first rod secured to the guide member which is slidably mounted in the said barrel along a translation axis, and a second rod secured to the guide member and movable in unison with the first rod; and wherein the downstream guide member is extendable to contact a downstream guided surface located downstream of the friction stir slug in an extended position, and the downstream guide member has a retracted position in which the downstream guide member is offset vertically in an upward direction relative to said downstream guided surface such that the downstream guide member is spaced from said downstream guided surface and positioned vertically of said welding position of said friction stir slug, and, in the retracted position, the downstream guide member extends to a vertical height that differs from that of the friction stir lug more than 5 cm.

2. The welding tool according to claim 1, wherein the downstream guide member has a translation axis relative to an axis of the friction stir slug of between 10 and 20.

3. The welding tool according to claim 1, wherein the displacement member comprises at least one shifting cylinder connecting the downstream guide member to the base.

4. The welding tool according to claim 1, wherein the displacement member is configured to press the downstream guide member against the first surface, the second surface, or both the first and second surfaces with a predetermined pressure force.

5. The welding tool according to claim 1, wherein said downstream guide member is a guide roller.

6. The welding tool according to claim 1, wherein the upstream and downstream guide members are diametrically opposed with respect to the friction stir slug.

7. The welding tool according to claim 1, further comprising a detector for detecting a barrier downstream of said downstream guided surface.

8. The welding tool according to claim 1, wherein the friction stir welding tool is movable from the upstream position to the downstream position along the interface line of the first and second surfaces; wherein the friction stir slug is rotatable relative to the base of the welding tool; and wherein the welding tool is guided along the interface line with the upstream and downstream guide members such that both upstream and downstream guide members are in contact with at least one of said first and second surfaces and said downstream guide member is in contact with at least one of said first and second surfaces at the downstream guided surface located downstream of the friction stir slug.

9. The welding tool according to claim 8, wherein said downstream guide member is displaced during the moving of said welding tool from the upstream position to the downstream position.

10. The welding tool according to claim 8, wherein only one of said upstream guide member or said downstream guide member is displaced in the retracted position.

11. The welding tool according to claim 8, further comprising a barrier located downstream of the downstream guide member and wherein said downstream guide member is displaced in the retracted position to avoid said barrier.

12. The welding tool according to claim 8, wherein the two surfaces to be joined are fuselage panels.

13. The welding tool according to claim 12, wherein said barrier is located at one end of the fuselage panels.

14. The welding tool according to claim 8, wherein the friction stir welding tool is rotatable so that a displacement member is rotated from a downstream position to an upstream position.

Description

BRIEF DESCRIPTION OF THE DRAWING FIGURES

(1) The invention will be better understood on reading the description which will follow, given solely as an example and with reference to the accompanying figures in which:

(2) FIG. 1 is a schematic top view of two fuselage panels and a friction stir welding tool according to the prior art;

(3) FIG. 2 is a schematic top view of two fuselage panels and a friction stir welding tool according to the prior art during a welding step;

(4) FIG. 3 is a schematic side view of a welding tool according to the invention; and

(5) FIG. 4 is a schematic representation of two fuselage panels and a friction stir welding tool during a welding step.

(6) It must be noted that the figures provide a detailed description of the invention in order to implement the invention; the said figures may be used to better define the invention if necessary.

DETAILED DESCRIPTION

(7) Referring to FIG. 3, there is a welding tool 4 according to the invention which comprises a base 40 and a rotating friction stir slug 41 mounted in the said base 40. The friction stir slug 41 is positionable to a welding position to perform a weld along an interface line of two surfaces to be joined, such as two panels. For example, the friction stir slug can move to the welding position to perform a weld and can retract away from the welding position. Such a structure is known to those skilled in the art and will not be discussed in more detail.

(8) The welding tool 4 is adapted to move longitudinally in the downstream direction along the X axis oriented from upstream to downstream.

(9) According to the invention, the welding tool 4 comprises two guide members 7A, 7B connected to the said base 40 which are mounted upstream and downstream respectively of the friction stir slug 41 as shown in FIG. 3. In other words, the guide members 7A, 7B are diametrically opposed relative to each other with respect to the friction stir slug 41. In this example, the guide members 7A, 7B are identical and are each in the form of a guide roller known per se to those skilled in the art.

(10) Referring to FIG. 3, the welding tool 4 includes a displacement member 6A, 6B associated with each guide member 7A, 7B to move it in relation to the said base 40. Preferably, the displacement member 6A, 6B associated with each guide member 7A, 7B is in the form of a cylinder, preferably, a hydraulic cylinder. However, it goes without saying that other displacement members 6A, 6B may be suitable, for example, a pneumatic device, a ball joint coupling device, etc. Preferably, each guide member 7A, 7B is controlled by a push button.

(11) Thus, the references 6A, 6B include both the displacement members as well as the cylinders.

(12) Still referring to FIG. 3, the welding tool 4 thus includes a downstream cylinder 6A and an upstream cylinder 6B which connect the base 40 to the downstream guide member 7A and to the upstream guide member 7B respectively. Each cylinder 6A, 6B comprises a barrel 62 secured to the base 40 and a first rod 61, secured to the guide member 7A, 7B, which is slidably mounted in the said barrel 62 along a translation axis. Additionally, a second rod 63 can be secured to the guide member 7A, 7B, wherein the second rod 63 is movable in unison with the first rod 61. In other words, a guide member 7A, 7B can slide along the translation axis. Preferably, the angle 13 between the axis of the friction stir slug 41 and the translation axis of each displacement member 6A, 6B is between 10 and 20 so as to ensure a supporting force extending as close as possible to the normal direction of the welding surface.

(13) According to the invention, each guide member 7A, 7B can be moved between at least one guiding position in which the guide member 7A, 7B extends opposite the friction stir slug 41, that is to say, in the welding plane extending orthogonally to the axis of the friction stir slug 41, and at least one retracted position.

(14) Referring to FIG. 4 (right side), in the guiding position, the downstream guide member 7A extends in a Z scout zone located downstream and facing the friction stir slug 41 while, in the same position, the upstream guide member 7B extends in a T trail area located upstream and facing the rotary slug 41. In other words, in the guiding position, each guide member 7A, 7B is in the immediate vicinity of the friction stir slug 41.

(15) In this example, in the guiding position, each guide member 7A, 7B extends to the same vertical height as the friction stir slug 41 and, preferably within 3 cm of the latter in the longitudinal X direction according to which the welding tool 4 moves.

(16) Referring to FIG. 3, in the retracted position, the downstream guide member 7A is offset from the said scout area Z. Similarly, in the same position, the upstream guide member 7B is offset from the said trail area T (not shown in the figures). In other words, in the retracted position, a guide member 7A, 7B is spaced from the friction stir slug 41.

(17) In this example, in the retracted position, a guide member 7A, 7B extends to a vertical height that differs from that of the friction stir slug 41, preferably more than 5 cm, or more than 8 cm. Preferably, the longitudinal distance between a guide member 7A, 7B and the friction stir slug 41 is greater in the retracted position than in the guiding position due to the inclination between the axis of the friction stir slug 41 and the translation axis of each displacement member 6A, 6B.

(18) Alternatively, in the retracted position, a guide member 7A, 7B may extend to the same vertical height as the friction stir slug 41 but may be offset laterally. To this end, the displacement member may be in the form of a ball or a sliding pin.

(19) In a preferred aspect of the invention, the displacement member 6A, 6B associated with each guide member 7A, 7B is configured to force the said guide member 7A, 7B against a wall with a predetermined pressure force. In this case, the hydraulic pressure of each cylinder 6A, 6B can be controlled in order to apply a predetermined pressure force on the panels P1, P2 so as to immobilise them firmly against an anvil 5 during welding as will be presented below. Thus, each guide member 7A, 7B can apply a pressure force that is independent of the pressure force applied by the friction stir slug 41, which helps improve the pressing of the panels P1, P2 without altering the quality of the friction stir welding. In practice, each guide member 7A, 7B can apply a pressure force between 0 and 3.3 kN, preferably 1 kN.

(20) Preferably, the welding tool 4 comprises detection means (not shown) for automatically controlling movement of at least one of the guide members 7A, 7B in the retracted position in case of detection of a barrier 3 so that the barrier 3 does not come into contact with the guide members 7A, 7B. The detection means are preferably in the form of a detector camera, but it is understood that other detection means may be suitable, for example, a presence sensor, a range finder, an inductive sensor, etc.

(21) The invention has been presented for a welding tool 4 having only two guide members 7A, 7B but it goes without saying that the invention also applies to a welding tool 4 having only one guide member or more than two guide members.

(22) An example of implementation of a method of joining two panels according to the invention will now be presented with reference to FIG. 4.

(23) As illustrated in FIG. 4, the welding tool 4 moves in the downstream direction (right to left in FIG. 4) along an interface line 20 formed between two panels P1, P2 placed against each other on an anvil 5 as illustrated for example in FIG. 1; the anvil 5 acts as a counter-brace. During its movement, the friction stir slug 41 is rotated relative to the base 40 of the welding tool 4 and comes into contact with the material of the two panels P1, P2 so as to perform a welding step.

(24) During the welding step, the guide members 7A, 7B are in the guiding position and come into contact with at least one of the said panels P1, P2 in order to press them against the anvil 5. Preferably, the pressure force provided by each guide member 7A, 7B is adjusted to ensure optimum pressing of the panels P1, P2 against the anvil 5. In this example, the hydraulic pressure provided to each hydraulic cylinder 6A, 6B is adapted to achieve the desired pressure force.

(25) Given the presence of a barrier 3 at the downstream end of the interface line 20, the method includes a step of moving the downstream guide member 7A in its retracted position such that the downstream guide member 7A is offset relative to the scout area Z. As illustrated in FIG. 4, the downstream guide member 7A is offset vertically in an upwards direction by the downstream displacement member 6A to no longer be in contact with the panels P1, P2 and to extend over the barrier 3. A vertical deflection of over 8 cm preferably allows the downstream guide member 7A to pass over a mounting clip of a vertical height of 6 cm.

(26) Thus, the friction stir slug 41 can weld the interface line 20 until it reaches the barrier 3. It is preferably no longer necessary to use additional fastening means as in the prior art.

(27) Preferably, the upstream guide member 7B remains in the guiding position to retain a pressure force on the panels P1, P2. The guiding by a single guide member 7B presents no problem when the barrier 3 is located at one end of a panel P1, P2, given that the pressing force necessary for pressing an end of a panel P1, P2 is lower.

(28) Preferably, the step of moving the said downstream guide member 7A is performed during the upstream to downstream movement of the said welding tool 4 in order to keep the same quality of welding throughout the length of the interface line 20. In other words, the displacement of the welding tool 4 does not stop during movement of the guide member 7A, 7B but is performed in a single pass to obtain a high quality welding bead. Preferably, the welding tool 4 is moved in the downstream direction at constant speed. Thus, the mechanical properties of the panels are not adversely affected during welding.

(29) Preferably, when the welding tool 4 comprises automatic detection means, the step of moving the said downstream guide member 7A is performed without an operator in case of detection of a barrier downstream of the said scout area Z. Thus, this speeds up the welding of the panels having barriers located at different positions.

(30) If the welding tool 4 is moved in the opposite direction from downstream to upstream (to the right with reference to FIG. 4), the upstream guide member 7B may also be retracted to avoid a barrier 3. In other words, the welding tool 4 according to the invention can preferably be used in both directions in order to accelerate welding of multiple panels. Alternatively, the base 40 of the welding tool 4 can be rotated 180 when only the downstream guide member 7A is linked to a downstream displacement member 6A so as to avoid a barrier 3 during a movement from left to right.

(31) The invention has been presented for the assembly of two panels but it is understood that it applies to the assembly of various components, in particular, the assembly of a stiffener on a panel.