Assembly method using friction stir welding, sacrificial shim and welding plate equipped with a sacrificial shim

Abstract

This method for joining a first element with a second element comprises a step of positioning (8) a sacrificial shim against a surface of the first element, a step of creating (18) a weld bead by friction stir welding of the first element with the second element, the weld bead creation step (18) including guiding a tool equipped with a welding pin so that the pin penetrates the sacrificial shim and then passes through the surface of the first element and / or passes through the surface of the first element and then withdraws from the sacrificial shim, as well as a step of removing the sacrificial shim. Figure for the abstract: Fig 1

Description

Title of the invention: Assembly method by friction stir welding, sacrificial shim and welding plate equipped with a sacrificial shim technical field

[0001] The invention relates to the technical field of friction stir welding assembly processes, also known as "friction stir welding" in Anglo-Saxon terms.

[0002] In particular, the present invention relates to a method of assembling a first element with a second element, a sacrificial wedge for producing a weld bead by friction stir and a welding plate comprising such a sacrificial wedge. Previous techniques

[0003] In industry, particularly in the aeronautical industry, it is common to assemble several elements together. For example, it is known to assemble a stiffener onto a structural panel of an aircraft in order to stiffen the structural panel.

[0004] This assembly can be carried out by friction stir welding using a tool equipped with a rotating pin adapted to stir together the materials of the elements to be assembled and thus form a weld bead between the elements.

[0005] However, friction stir welding creates surface defects at both ends of the weld bead, where the weld pin penetrates and / or withdraws from the material. These surface defects are prime locations for fracture initiation and / or corrosion.

[0006] It is known to manually correct these surface defects, in particular by drilling through the material at both ends of the weld bead and then filling the holes thus created, notably by using a rivet. Manually correcting these surface defects is a tedious operation. Moreover, manually correcting these surface defects degrades the visual appearance of the part. Description of the invention

[0007] The present invention therefore aims to overcome all or part of the aforementioned disadvantages and to propose a rapid assembly process reducing the appearance of surface defects.

[0008] The present invention relates to a method for assembling a first element with a second element, comprising a step of positioning a sacrificial shim against a surface of the first element, a step of creating a weld bead by friction stir welding of the first element with the second element, the step of creating the bead comprising guiding a tool equipped with a pin welding such that the pin penetrates the sacrificial wedge and then passes through the surface of the first element and / or passes through the surface of the first element and then withdraws from the sacrificial wedge, as well as a step of removing the sacrificial wedge.

[0009] Thus, a surface defect is formed on the sacrificial wedge when the pin enters the sacrificial wedge and / or withdraws from the sacrificial wedge, the pin not forming the surface defect on the first element and / or on the second element.

[0010] Optionally, the positioning of the sacrificial wedge includes gluing and / or welding the wedge onto the first element and / or onto the second element.

[0011] Advantageously, the assembly method includes guiding the tool so that the pin is only in contact with the first element and the sacrificial shim when the pin passes through the surface of the first element. Thus, the sacrificial shim is not welded to the second element.

[0012] Optionally, the process includes a step of sanding the surface of the first element and a step of applying sealant around the perimeter of a contact surface between the first element and the second element.

[0013] Advantageously, the tool guidance includes the use of a robotic arm programmed to guide the tool.

[0014] In one embodiment, the assembly process includes the use of a sacrificial wedge equipped with a socket, the wedge positioning step including the positioning of the socket opposite the surface of the first element, the tool guidance being carried out so that the pin enters the sacrificial wedge, is guided through the socket and then passes through the surface of the first element and / or so that the pin passes through the surface of the first element, is guided through the socket and then withdraws from the sacrificial wedge.

[0015] Optionally, the assembly method includes the use of a sacrificial wedge provided with a wall forming a slope, the guidance of the tool being carried out so that the trajectory of the tool follows the slope of the sacrificial wedge when the pin crosses the surface of the first element.

[0016] Optionally, the assembly method includes the use of a sacrificial wedge linked to the first element, a priming being formed in the link of the sacrificial wedge to the first element.

[0017] The present invention also relates to a sacrificial wedge for the production of a weld bead by friction stir welding adapted for the implementation of an assembly process as defined above.

[0018] The present invention also relates to a welding plate comprising a first element intended to be assembled with a second element by implementing an assembly process as defined above, the plate comprising a sacrificial shim attached to a surface of the first element, a starter being formed in the connection of the sacrificial wedge to the first element. Brief description of the drawings

[0019] 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:

[0020] [Fig-1] schematically illustrates an assembly method according to the invention;

[0021] [Fig.2] schematically illustrates the assembly of a first element with a second element according to a first method of implementing the invention;

[0022] [Fig.3] schematically illustrates the assembly of the first element with the second element according to a second method of implementing the invention;

[0023] [Fig.4] schematically illustrates the assembly of the first element with the second element according to a third method of implementing the invention;

[0024] [Fig.5] schematically illustrates the assembly of the first element with the second element according to a fourth embodiment of the invention;

[0025] [Fig.6] schematically illustrates a welding plate according to the invention arranged on the second element in perspective; and

[0026] [Fig.7] schematically illustrates a profile view of [Fig.6]. Detailed description

[0027] Fig. 1 schematically represents the steps enabling the implementation of a method for assembling a first element 2 with a second element 4, for example the assembly of a stiffener on a structural panel of an aircraft.

[0028] The first element 2 comprises, for example, an aluminum alloy or any other alloy that can be welded by friction stir.

[0029] The second element 4 comprises, for example, an aluminum alloy or any other alloy that can be friction stir welded.

[0030] Fig. 2 schematically represents the assembly of the first element 2 with the second element 4, the first element 2 being arranged on the second element 4 so that the first element 2 covers the second element 4 on a contact surface 6.

[0031] A positioning step 8 is first performed of at least one sacrificial wedge against the first element 2. For example, an entry sacrificial wedge 10 is positioned against an entry surface 12 of the first element 2 and an exit sacrificial wedge 14 against an exit surface 16 of the first element 2.

[0032] Advantageously, the sacrificial inlet wedge 10 is disposed on the second element 4 and bears against the inlet surface 12 of the first element 2, the sacrificial outlet wedge 14 being disposed on the second element 4 and bearing against the outlet surface 16 of the first element 2.

[0033] In one embodiment, at least one of the sacrificial inlet or outlet shims 10, 14 is bonded to the first element 2 and / or the second element 4, in particular using a temporary adhesive 17a intended to be removed at the end of the assembly process. Alternatively, at least one of the sacrificial inlet or outlet shims 10, 14 is welded to the first element 2 and / or the second element 4, in particular by making a weld point 17b intended to be removed at the end of the assembly process.

[0034] A weld bead 20 is then produced by friction stir welding of the first element 2 with the second element using a friction stir welding tool 22 (step 18).

[0035] The tool 22 comprises, for example, a tubular portion 24 and a pin 26, in particular rotatable and adapted for mixing together the materials of the first and second elements 2, 4 to be assembled, the pin 26 extending the tubular portion 24 so that the tubular portion 24 forms a shoulder 28. The length of the pin 26, taken along the longitudinal direction of the tubular portion 24, is adapted to the thickness of the first element 2. In particular, the length of the pin 26 is greater than the thickness of the first element 2 in order to allow the assembly by friction mixing of the first element 2 onto the second element 4. Several positions of the tool 22 during the step of making the weld bead 20 are shown.

[0036] During the production of the weld bead 20, the pin 26 progressively penetrates the sacrificial entry wedge 10 towards the second element 4 and the first element 2, then crosses the entry surface 12 of the first element 2, here a lateral entry surface of the first element 2.

[0037] In the example shown, the sacrificial entry wedge 10 is of the same thickness as the first element 2. The pin 26 of the tool 22 penetrates the sacrificial entry wedge 10 until the shoulder 28 of the tool 22 is in contact with a flat upper surface 30 of the sacrificial entry wedge 10. The tool 22 is then translated along a path for forming the weld bead 20 through the entry surface 12 of the first element 2, here in the direction of the sacrificial exit wedge 14. The shoulder 28 of the tool 22 being in contact with the sacrificial entry wedge 10 before passing through the entry surface 12 of the first element 2, the weld bead 20 is formed at the interface between the first element 2 and the second element 4 up to the entry surface. 12 of the first element 2.

[0038] The shoulder 28 of the tool 22 then travels over an upper surface 32 of the first element 2 towards the sacrificial exit wedge 14 in order to continue the formation of the weld bead 20 at the interface between the first element 2 and the second element 4.

[0039] The tool 22 not directly penetrating the upper surface 32 of the first element 2, no surface defect is formed on the upper surface 32 of the first element 2.

[0040] Alternatively, the pin 26 of the tool 22 penetrates the sacrificial inlet wedge 10 so that the pin 26 is only in contact with the first element 2 and the sacrificial wedge when the pin 26 crosses the inlet surface 12 of the first element 2. Since the pin 26 is not in contact with the second element 4 when the pin 26 crosses the inlet surface 12 of the first element 2, the weld bead 20 is not formed at the interface between the first element 2 and the second element 4 up to the inlet surface 12 of the first element 2, the sacrificial inlet wedge 10 is therefore not welded with the second element 4.

[0041] Advantageously, during the production of the weld bead 20 (step 18), a programmed robotic arm (not shown) is used to guide the tool 22 equipped with the pin 26. Thus, the assembly process is fast and automated. At least one of the sacrificial inlet and outlet shims 10, 14 includes, for example, markings to facilitate the guidance of the robotic arm.

[0042] Preferably, at least one of the sacrificial inlet and outlet shims 10, 14 comprises an aluminum alloy or any other alloy constituting the first element 2 or the second element 4, in particular to facilitate friction stir welding.

[0043] The guidance of the tool 22 continues until the pin 26 passes through the exit surface 16 of the first element 2, here a lateral exit surface of the first element 2. The tool 22 then gradually withdraws from the sacrificial exit wedge 14 so that the pin 26 of the tool 22 moves away from the second element 4 and the first element 2. The shoulder 28 of the tool 22 being in contact with the sacrificial exit wedge 14 after passing through the exit surface 16 of the first element 2, the weld bead 20 is formed at the interface between the first element 2 and the second element 4 up to the exit surface 16. The weld bead 20 is formed here at the interface between the first element 2 and the second element 4 from the entry surface 12 to the exit surface 16.

[0044] Alternatively, the shoulder 28 of the tool 22 breaks contact with the first element 2 before the pin 26 of the tool 22 crosses the exit surface 16 so that the pin 26 is in contact only with the first element 2 and the sacrificial exit wedge 14 when the pin 26 crosses the exit surface 16. Thus the weld bead 20 is not formed at the interface between the first element 2 and the second element 4 up to the exit surface 16 of the first element 2, the sacrificial exit wedge 14 then not being welded with the second element 4.

[0045] Since the tool 22 does not withdraw directly from the upper surface 32 of the first element 2, no surface defect is formed on the upper surface 32 of the first element 2.

[0046] The sacrificial wedge is so named because the surface defects 34 are formed in the sacrificial wedge and not in the first and second elements 2, 4.

[0047] Alternatively, a single sacrificial wedge is used, the pin 26 of the tool 22 penetrating the single sacrificial wedge and withdrawing from the single sacrificial wedge so that both ends of the weld bead 20 are formed in the single sacrificial wedge.

[0048] Finally, a step 36 is performed to remove the sacrificial inlet wedge 10 and the sacrificial outlet wedge 14.

[0049] Optionally, following the removal step 36, a sanding step 38 is carried out on the entry surface 12 of the first element 2 and on the entry surface 12 of the first element 2.

[0050] Advantageously, a step of applying sealant 40 is finally carried out on a perimeter of the contact surface 6 between the first element 2 and the second element 4 in order to guarantee the sealing of the assembly of the first element 2 with the second element 4.

[0051] Fig. 3 schematically represents the use of an entry sacrificial wedge 10 equipped with a socket 42 and an exit sacrificial wedge 14 equipped with a socket 42.

[0052] Step 8 of positioning the wedge includes positioning the cavity 42 of the sacrificial inlet wedge 10 opposite the inlet surface 12 of the first element 2 and positioning the cavity 42 of the sacrificial outlet wedge 14 opposite the outlet surface 16 of the second element 4.

[0053] The guidance of the tool 22 is carried out so that the pin 26 of the tool 22 enters the sacrificial inlet wedge 10, is guided through the recess 42 of the sacrificial inlet wedge 10 and then passes through the inlet surface 12 of the first element 2. Then, the shoulder 28 of the tool 22 travels on the upper surface 32 of the first element 2, then the pin 26 of the tool 22 passes through the exit surface 16 of the first element 2, is guided through the recess 42 of the sacrificial exit wedge 14 and then withdraws from the sacrificial exit wedge 14.

[0054] The cavity 42 of the sacrificial inlet wedge 10 allows the sacrificial inlet wedge 10 not to be welded to the first element 2 during the welding bead 20 fabrication step 18. The cavity 42 of the sacrificial outlet wedge 14 allows the sacrificial outlet wedge 14 not to be welded to the first element 2 during the welding bead 20 fabrication step 18.

[0055] Figure 4 schematically represents the use of an entry sacrificial wedge 10 having an upper wall forming a slope 44 relative to the flat upper surface 32 of the first element 2. The exit sacrificial wedge 14 is also equipped with an upper wall forming a slope 44 in relation to the upper flat surface 32 of the first element 2.

[0056] Step 8 of positioning the wedge includes positioning the inlet sacrificial wedge 10 so that the thickness of the inlet sacrificial wedge 10 increases as it moves away from the inlet surface 12, and positioning the outlet sacrificial wedge 14 so that the thickness of the outlet sacrificial wedge 14 increases as it moves away from the outlet surface 16.

[0057] The guidance of the tool 22 is carried out so that the tool 22 follows the slope 44 of the sacrificial entry wedge 10 when the pin 26 crosses the entry surface 12 of the first element 2, the shoulder 28 of the tool 22 being in support against the slope 44 of the sacrificial entry wedge 10.

[0058] The guidance of the tool 22 is carried out so that the tool 22 follows the slope 44 of the sacrificial outlet wedge 14 when the pin 26 crosses the outlet surface 16 of the first element 2, the shoulder 28 of the tool 22 being in contact with the slope 44 of the sacrificial outlet wedge 14.

[0059] The slope 44 of the sacrificial entry wedge 10 allows, together with the height of the pin 26 of the tool 22, to determine the positioning of the weld bead 20 on the side of the entry surface 12 at the interface between the first element 2 and the second element 4 and optionally to not weld the sacrificial entry wedge 10 to the first element 2 during the realization step 18 of the weld bead 20.

[0060] The slope 44 of the sacrificial outlet wedge 14 allows, together with the height of the pin 26 of the tool 22, to determine the positioning of the weld bead 20 on the side of the outlet surface 16 at the interface between the first element 2 and the second element 4 and optionally to not weld the sacrificial outlet wedge 14 to the first element 2 during the step of making the weld bead 20 18.

[0061] Figure 5 schematically represents an alternative embodiment of the sacrificial inlet and outlet wedges 10, 14 of Figure 4. The sacrificial inlet wedge 10 here comprises an angular portion 46 configured to fit the inlet surface 12 of the first element 2, the inlet surface 12 here being formed by the lateral inlet surface of the first element 2 and a portion of the upper surface 32 of the first element 2. The sacrificial outlet wedge 14 here comprises an angular portion 46 configured to fit the outlet surface 16 of the first element 2, the outlet surface 16 here being formed by the lateral outlet surface of the first element 2 and a portion of the upper surface 32 of the first element 2.

[0062] Step 8 of positioning the wedge includes positioning the sacrificial inlet wedge 10 so that the angular portion 46 of the sacrificial inlet wedge 10 fits the inlet surface 12 of the first element 2, the slope 44 of the sacrificial inlet wedge 10 extending the upper surface 32 of the first element 2 so that the thickness of the sacrificial inlet wedge 10 increases as it moves away from the inlet surface 12.

[0063] Step 8 of positioning the wedge also includes positioning the exit sacrificial wedge 14 so that the angular portion 46 of the exit sacrificial wedge 14 fits the exit surface 16 of the first element 2, the slope 44 of the exit sacrificial wedge 14 extending the upper surface 32 of the first element 2 so that the thickness of the exit sacrificial wedge 14 increases as it moves away from the exit surface 16.

[0064] The angular portion 46 of the sacrificial entry wedge 10 comprises a first wall intended to come into contact with the lateral entry wall of the first element 2 and a second wall intended to come into contact with the upper surface 32 of the first element 2. The angular portion 46 of the sacrificial exit wedge 14 comprises a first wall intended to come into contact with the lateral exit wall of the first element 2 and a second wall intended to come into contact with the upper surface 32 of the first element 2.

[0065] Advantageously, the thickness of the sacrificial inlet wedge 10, taken as an extension of the first wall of the angular portion 46 of the sacrificial inlet wedge 10, between the second wall of the angular portion 46 of the sacrificial inlet wedge 10 and the surface of the sloping wall 44 of the sacrificial inlet wedge 10, is greater than the height of the pin 26 of the tool 22. Thus, when the angular portion 46 of the sacrificial inlet wedge 10 conforms to the inlet surface 12, guiding the tool 22 so that the shoulder 28 of the tool 22 follows the slope 44 of the sacrificial inlet wedge 10 ensures that the pin 26 of the tool 22 is in contact only with the sacrificial inlet wedge 10 and the first element 2 when the pin 26 of the tool 22 crosses the entry surface 12, and thus to ensure that the sacrificial entry wedge 10 is not welded with the second element 4.

[0066] Advantageously, the thickness of the sacrificial outlet wedge 14, taken as an extension of the first wall of the angular portion 46 of the sacrificial outlet wedge 14, between the second wall of the angular portion 46 of the sacrificial outlet wedge 14 and the surface of the slope 44 of the sacrificial outlet wedge 14, is greater than the height of the pin 26 of the tool 22. Thus, when the angular portion 46 of the sacrificial outlet wedge 14 conforms to the outlet surface 16, the guidance of the tool 22, such that the shoulder 28 of the tool 22 follows the slope 44 of the sacrificial outlet wedge 14, ensures that the pin 26 of the tool 22 is in contact only with the sacrificial outlet wedge 14 and the first element 2 when the pin 26 of the tool 22 crosses the exit surface 16, and thus ensures that the sacrificial exit wedge 14 is not welded with the second element 4.

[0067] Figure 6 schematically represents a welding plate 48 arranged on the second element 4, for example a structural panel of an aircraft.

[0068] The welding plate 48 includes the first element 2, for example a stiffener, as well as an entry sacrificial wedge 10 linked to the first element 2 and an exit sacrificial wedge 14 linked to the first element 2.

[0069] Fig. 7 schematically illustrates the connection of the sacrificial outlet wedge 14 with the first element 2. The sacrificial outlet wedge 14 came from the same material as the first element 2, a priming 50 being formed in the connection of the sacrificial outlet wedge 14 to the first element 2.

[0070] Step 8 of positioning the sacrificial wedge 10, 14 is done naturally during the positioning of the first element 2 on the second element 4.

[0071] The starter 50 makes it easier to remove the sacrificial wedge 10, 14 step 36, in particular by making it possible to bend the welding plate 48 at the point of the initiated connection between the first element 2 and the sacrificial wedge 10, 14.

Claims

Demands

1. A method for assembling a first element (2) with a second element (4), the first element (2) being positioned on the second element (4) such that the first element (2) overlaps the second element (4) on a contact surface (6), comprising: a step of positioning (8) a sacrificial shim (10, 14) against a surface (12, 16) of the first element (2), a step of forming (18) a weld bead (20) by friction stir welding of the first element (2) with the second element (4), the step of forming the weld bead (20) comprising guiding a tool (22) equipped with a welding pin (26) such that the pin (26) penetrates the sacrificial shim (10, 14) and then passes through the surface (12, 16) of the first element (2) and / or through the surface (12, 16) of the first element (4) (2) then withdraws from the sacrificial hold (10, 14), as well as a withdrawal step (36) of the sacrificial hold (10, 14), characterized in that the sacrificial hold (10,14) is arranged on the second element (4).

2. Assembly method according to claim 1, wherein the positioning of the sacrificial wedge (10, 14) includes gluing and / or welding the wedge onto the first element (2) and / or onto the second element (4).

3. Assembly method according to any one of claims 1 and 2, comprising guiding the tool (22) so that the pin (26) is in contact only with the first element (2) and the sacrificial wedge (10, 14) when the pin (26) crosses the surface (12, 16) of the first element (2).

4. Assembly method according to any one of claims 1 to 3, comprising a sanding step (38) of the surface (12, 16) of the first element (2) and a step of applying sealant (40) around the perimeter of a contact surface (6) between the first element (2) and the second element (4).

5. Assembly method according to any one of claims 1 to 4, wherein the guidance of the tool (22) comprises the use of a robotic arm programmed to guide the tool (22).

6. An assembly method according to any one of claims 1 to 5, comprising the use of a sacrificial wedge (10, 14) having a recess (42), the positioning step (8) of the wedge comprising positioning the recess (42) opposite the surface (12, 16) of the first element (2), the guidance of the tool (22) being carried out so that the pin (26) enters the sacrificial wedge (10, 14), is guided through the socket (42) then crosses the surface (12, 16) of the first element (2) and / or so that the pin (26) crosses the surface (12, 16) of the first element (2), is guided through the socket (42) then withdraws from the sacrificial wedge (10, 14).

7. Assembly method according to any one of claims 1 to 6, comprising the use of a sacrificial wedge (10, 14) provided with a wall forming a slope (44), the guidance of the tool (22) being carried out so that the trajectory of the tool (22) follows the slope (44) of the sacrificial wedge (10, 14) when the pin (26) crosses the surface (12, 16) of the first element (2).

8. Assembly method according to any one of claims 1 to 7, comprising the use of a sacrificial wedge (10, 14) linked to the first element (2), a starter being formed in the linkage of the sacrificial wedge (10, 14) to the first element (2).

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