Spot welding electrode and corresponding spot welding assembly and spot welding device

Abstract

The spot welding electrode has a working surface (14) for contact with a site (4, 6) to be welded, wherein the working surface (14) is convex and is contoured along a longitudinal axis (A).

Description

Technical Field

[0001] The present invention relates to the technical field of spot welding, in particular to spot welding of spot welding portions of nuclear components, more specifically, spot welding of structural portions of nuclear fuel assemblies. Background Art

[0002] In the field of nuclear power plants, it is crucial to ensure that the welds are correctly made where they are needed, thereby ensuring controlled and reliable welds which are crucial for durability and safety.

[0003] The nuclear fuel assembly of a pressurized water reactor consists of a structure and fuel rod bundles supported by the structure.

[0004] The structure includes a lower nozzle and an upper nozzle spaced apart along an assembly axis, a guide tube extending longitudinally between the lower nozzle and the upper nozzle, and a plurality of spacer grids distributed between the lower nozzle and the upper nozzle, the guide tube extending through the spacer grids.

[0005] Fuel rods are received between the lower and upper nozzles, extending through spacer grids that retain the fuel rods longitudinally along the assembly axis and laterally in a laterally spaced relationship.

[0006] Each spacer grid is secured to each guide tube, for example via at least one pair of tabs of the spacer grid, the two tabs of each pair contacting opposite sides of the guide tube, each tab having an arcuate profile matching the outer surface of the guide tube.

[0007] To weld two tabs of a pair of tabs to the guide tube, a spot welding gun may be used that has two electrodes, each having a spherical working surface, the spot welding gun being used to press the working surface of each electrode against the corresponding tab and generate an electric current between the two electrodes to spot weld each tab to the guide tube.

[0008] However, it is necessary to position the electrode very precisely on the tab to ensure a controlled and reliable weld spot is produced between the tab and the guide tube. Imprecise positioning of the electrode relative to the tab may result in unreliable spot welds and / or shortened electrode life. Summary of the Invention

[0009] One of the objects of the present invention is to provide a spot welding electrode which simplifies the positioning of the spot welding electrode during the spot welding operation, allows the surface of the welding area to be reduced with satisfactory mechanical strength, and can exhibit a long life.

[0010] To this end, the invention proposes a spot welding electrode having a working surface for contacting a location to be welded, wherein the working surface is convex and profiled along a longitudinal axis.

[0011] Conventional spot welding electrodes with spherical working surfaces can be difficult to position accurately on the convex surface of a weld.

[0012] Providing an electrode with a contoured working surface along the longitudinal axis allows the spot welding electrode to properly contact the convex surface of the weld at multiple locations along the longitudinal axis of the electrode. This makes positioning of the electrode easier.

[0013] In particular, when the convex surface of the weld is contoured along the weld axis, the electrode can be oriented so that the longitudinal axis is at a non-zero angle to the weld axis so that the working surface of the electrode and the convex surface of the weld are in point contact with each other at points located along the generatrix of the working surface of the electrode and the generatrix of the convex surface of the weld.

[0014] In a specific embodiment, the spot welding electrode includes one or more of the following optional features, taken alone or in any technically feasible combination:

[0015] - The working surface is a portion of a cylindrical surface centered on the electrode working surface axis;

[0016] - the radius of curvature of the working surface is between 8 mm and 12 mm;

[0017] The working surface has a width between 2 and 4 mm, this width being taken transversely between its two side edges parallel to the longitudinal axis.

[0018] The invention also relates to a spot welding assembly comprising an electrode holder and at least one spot welding electrode as defined above.

[0019] In a specific embodiment, the spot welding assembly includes one or more of the following optional features, taken alone or in any technically feasible combination:

[0020] - each spot welding electrode is removably attached to the electrode holder to allow replacement of a used spot welding electrode with a new one;

[0021] - one of the electrode holder and each spot welding electrode has a mounting portion configured for insertion into a mounting hole of the other;

[0022] - each spot welding electrode has a mounting portion configured for insertion into a mounting hole of an electrode holder;

[0023] -The spot welding assembly includes two spot welding electrodes;

[0024] - profiling of the working surfaces of the two spot welding electrodes along coplanar respective longitudinal axes;

[0025] - the working surface of each spot welding electrode is a portion of a cylindrical surface;

[0026] - The working surfaces of the spot welding electrodes have the same radius of curvature;

[0027] - the longitudinal axes of the working surfaces of the two spot welding electrodes define a non-zero angle between them;

[0028] The longitudinal axes of the two spot welding electrodes define between them an angle comprised between 60° and 120°, in particular between 80° and 100°.

[0029] The present invention also relates to a spot welding device comprising two spot welding assemblies and a spot welding gun, one or each spot welding assembly being as defined above, the spot welding gun being configured for supporting the two spot welding assemblies and for generating an electric current between the two spot welding assemblies when the two spot welding assemblies are pressed against the parts to be welded together.

[0030] In a specific embodiment, the spot welding device includes one or more of the following optional features, taken alone or in any technically feasible combination:

[0031] the spot welding gun comprises two support members, each support member being configured to support a respective one of the two spot welding assemblies, the two support members being movable between a rest position in which the two spot welding assemblies are moved apart and a welding position in which the two spot welding assemblies are moved closer together to weld the two parts;

[0032] The two supporting members are movable translationally relative to each other, for example telescopically. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The invention and its advantages will be better understood on reading the following description given purely by way of non-limiting example and with reference to the accompanying drawings, in which:

[0034] - Figure 1 is a schematic side view of a spot welding apparatus including two spot welding assemblies;

[0035] - Figure 2 is a perspective view of a spot welded assembly according to an example;

[0036] - Figure 3 yes Figure 2 Front view of the spot welded assembly;

[0037] - Figure 4 and Figure 5 It is along the Figure 3 The arrows V4 and V5 show two different viewing directions. Figure 2 A side view of a spot-welded assembly;

[0038] - Figure 6is a perspective view of a spot-welded assembly according to another example;

[0039] - Figure 7 is a schematic side view illustrating contact between the working surface of a spot welding electrode and the convex surface of a weld. DETAILED DESCRIPTION

[0040] like Figure 1 As shown, the spot welding device 2 is configured for spot welding locations to be welded or "welding locations" 4, 6 placed in contact. The welding locations 4, 6 are preferably electrically conductive. The welding locations are preferably made of metal.

[0041] like Figure 1 As shown, the welds 4 , 6 comprise, for example, a tube extending along the tube axis (weld 6 ) and two tabs (weld 4 ) positioned on the tube at two diametrically opposed positions relative to the tube axis.

[0042] Each tab is for example in the shape of a portion of a cylinder extending along a tab axis.When the tab is positioned on the tube, the tab axis coincides with the tube axis.

[0043] Each welding location 4 configured as a tab has a convex surface 4A.

[0044] The spot welding device 2 comprises two spot welding assemblies 8 , each comprising an electrode holder 10 and at least one spot welding electrode 12 , each spot welding electrode 12 being supported by the electrode holder 10 and comprising a working surface 14 for contacting one of the two welding locations 4 , 6 .

[0045] The spot welding device 2 includes a welding gun 15 that supports two spot welding assemblies 8 and is configured to press the two spot welding assemblies 8 onto the welding locations 4, 6, each spot welding assembly 8 being in contact with a corresponding one of the welding locations 4, 6 via a working surface 14 of each spot welding electrode 12 of the spot welding assembly 8.

[0046] Preferably, the working surface 14 of each spot welding electrode 12 of each spot welding assembly 8 contacts the convex surface 4A of one of the weld locations 4 , 6 .

[0047] The welding gun 15 comprises, for example, two support members 16, each support member 16 being configured for supporting a respective one of the two spot welding assemblies 8, the two support members 16 being movable relative to each other between a rest position in which the two spot welding assemblies 8 are moved apart and a welding position in which the two spot welding assemblies 8 are moved closer together.

[0048] The rest position is suitable for placing two spot welding assemblies 8 on both sides of the welding location 4, 6. The welding position is suitable for clamping the welding location 4, 6 between the two spot welding assemblies 8.

[0049] The welding gun 15 is for example configured for moving the two support members 16 translationally relative to each other along a clamping direction between a rest position and a welding position (see Figure 1 Arrow F on the top).

[0050] The two supporting members 16 are, for example, mounted telescopically one to the other so as to be movable in translation relative to each other between a rest position and a welding position.

[0051] The spot welding device 2 comprises, for example, an actuator 18 configured for moving the two support members 16 relative to each other between a rest position and welding.

[0052] The actuator 18 is, for example, an electric actuator. In a variant, the actuator is a hydraulic actuator or a pneumatic actuator.

[0053] The actuator 18 is, for example, a linear actuator. In a variant, the actuator 18 is a rotary actuator.

[0054] A transmission may optionally be provided between the actuator 18 and the support members 16 , for example for converting a rotational motion generated by the actuator 18 into a translational motion applied to at least one support member 16 .

[0055] The spot welding device 2 is configured for generating an electric current between the spot welding electrode(s) 12 of one spot welding assembly 8 and the spot welding electrode(s) 12 of another spot welding assembly 8 .

[0056] When such current is generated when the spot welding assembly 8 clamps the welds 4 , 6 , the current circulates through the welds 4 , 6 , melting the material of the welds 4 , 6 at the interface(s) therebetween, thereby welding the welds 4 , 6 together.

[0057] Optionally, when the weld 4, 6 comprises a tube and two tabs arranged on opposite sides of the tube, a mandrel is inserted inside the tube to facilitate the flow of current from one tab to the other through the tube. The mandrel is preferably made of metal.

[0058] The spot welding device 2 includes an electrical feed unit 20, which is configured to generate a potential difference between the spot welding electrode(s) 12 of one spot welding assembly 8 and the spot welding electrode(s) 12 of the other spot welding assembly 8, so as to generate an electric current when the spot welding electrodes 12 of the welding assemblies 8 come into contact with the welding locations 4, 6.

[0059] The spot welding device 2 preferably includes an electrical control unit 22, which is configured for controlling the spot welding device 2 to perform a welding operation, and in particular for controlling the actuator 18 to control the movement of the support member 16 and / or controlling the electrical feed unit 20 to feed power to the spot welding electrode(s) 12 of the spot welding assembly 8.

[0060] The spot welding device 2 is configured, for example, so that when the spot welding assembly 8 is mounted on the support member 16, the working surface 14 of the spot welding electrode(s) 12 of one spot welding assembly 8 faces the working surface 14 of the spot welding electrode(s) 12 of another spot welding assembly 8.

[0061] Preferably, the working surface 14 of each spot welding electrode 12 of one spot welding assembly 8 faces the working surface 14 of the corresponding spot welding electrode 12 of another spot welding assembly 8 .

[0062] In the welding position of the support member 16 , the working surface 14 of each spot welding electrode 12 of one spot welding assembly 8 is aligned with the working surface 14 of the corresponding spot welding electrode 12 of the other spot welding assembly 8 .

[0063] In operation, the welding gun 15 supports the spot welding assembly 8. The weld locations 4, 6 are placed in contact.

[0064] The welding gun 15 is controlled so that the spot welding assembly 8 is in a rest position. The welding gun 15 is moved, for example, by a robot arm, to position the spot welding assembly 8 on both sides of the welding locations 4, 6 placed in contact with each other.

[0065] The welding gun 15 is controlled to move the spot welding assembly 8 to the welding position so that the spot welding electrodes 12 contact the welding locations 4, 6, and generate current between the (one or more) spot welding electrodes 12 of one spot welding assembly 8 and the (one or more) spot welding electrodes 12 of the other spot welding assembly 8 through the welding locations 4, 6.

[0066] The welding gun 15 is then controlled to move the spot welding assembly 8 back to the rest position.

[0067] The two spot welding assemblies 8 are similar or identical. Figures 2 to 5 Only one spot-welded assembly 8 is depicted.

[0068] like Figures 2 to 5 As shown, the spot welding assembly 8 includes an electrode holder 10 and at least one spot welding electrode 12 supported by the electrode holder 10 , each spot welding electrode 12 having a working surface 14 for contacting a welding location 4 , 6 (ie, a location to be welded).

[0069] Each spot welding electrode 12 is made of an electrically conductive material, preferably metal.

[0070] The working surface 14 of each spot welding electrode 12 is convex and contoured along a longitudinal axis A associated with that spot welding electrode 12 .

[0071] The profiled working surface 14 of each spot welding electrode 12 is constituted by numerous straight lines parallel to the longitudinal axis A, which pass through the contour of the working surface 14 of said spot welding electrode 12. Each straight line of the profiled surface is called a generatrix.

[0072] The working surface 14 of each spot welding electrode 12 preferably has a radius of curvature of between 8 mm and 12 mm at each point of the working surface 14 , and in particular has a radius of 10 mm at each point of the working surface 14 .

[0073] The working surface 14 of each spot welding electrode 12 is advantageously a portion of a cylindrical surface of circular cross-section centered about the longitudinal axis A.

[0074] In other words, the working surface 14 of each spot welding electrode 12 has a profile that is an arc of a circle when viewed along the longitudinal axis A associated with that spot welding electrode 12 .

[0075] In this case, the radius of curvature of the working surface 14 of each spot welding electrode 12 is constant.

[0076] Preferably, the radius of curvature of the working surface 14 of each spot welding electrode 12 , which is a portion of a cylindrical surface of circular cross-section, is preferably between 8 mm and 12 mm, and in particular is approximately 10 mm.

[0077] Preferably, each working surface 14 has a width W obtained between two side edges of the working surface 14 parallel to the electrode working surface axis A associated with this working surface 14. The width W is preferably between 2 mm and 4 mm.

[0078] Preferably, each working surface 14 has a length taken along the longitudinal axis A associated with this working surface 14. The length is preferably between 4 and 8 mm, in particular between 5 and 7 mm.

[0079] like Figures 2 to 5 As shown, the spot welding assembly 8 advantageously has two spot welding electrodes 12 .

[0080] The two spot welding electrodes 12 are spaced apart and there is a non-zero distance between the working surfaces 14 of the two spot welding electrodes 12 .

[0081] The two spot welding electrodes 12 are preferably arranged relative to each other such that the working surfaces 14 of the spot welding electrodes 12 are in linear contact with the same planar surface to which the two spot welding electrodes 12 are applied simultaneously.

[0082] Preferably, the respective longitudinal axes A of the two spot welding electrodes 12 are coplanar.

[0083] Preferably, the respective longitudinal axes A of the two spot welding electrodes 12 define a non-zero angle therebetween.

[0084] In this case, the angle between the longitudinal axes A of the two spot welding electrodes 12 is preferably between 60° and 120°, specifically between 80° and 100°, more specifically between 85° and 95°. In a preferred example, the angle between the longitudinal axes A of the two spot welding electrodes 12 is 88°.

[0085] The angle between the coplanar longitudinal axes A of the working surfaces 14 of the two spot welding electrodes 12 is obtained when viewed along a direction perpendicular to a plane defined by the longitudinal axes A of the working surfaces 14 of the two spot welding electrodes 12 .

[0086] The two spot welding electrodes 12 are preferably arranged relative to each other such that their working surfaces 14 are in linear contact with the same planar surface parallel to a plane defined by their coplanar longitudinal axes A.

[0087] In a preferred example, Figures 2 to 5 As shown, the working surface 14 of each spot welding electrode 12 is a portion of a cylindrical surface with a circular cross-section, the longitudinal axes A of the working surfaces 14 of the two spot welding electrodes 12 are coplanar, and the working surfaces 14 of the spot welding electrodes 12 have the same radius of curvature. Preferably, the longitudinal axes A of the working surfaces 14 of the two spot welding electrodes 12 define a non-zero angle therebetween.

[0088] The two spot welding electrodes 12 are preferably symmetrical with respect to a mid-plane P extending between the two spot welding electrodes 12 .

[0089] The spot welding assembly 8 is preferably symmetrical relative to the midplane P.

[0090] The electrode holder 10 is configured for supporting each spot welding electrode 12 and for fastening the electrode holder to the spot welding device 2 , in particular to a support member 14 of the spot welding device 2 .

[0091] The electrode holder 10 is, for example, provided with a fastening hole 24 configured for receiving a fastening member, such as a screw, to fasten the electrode holder 10 to the spot welding device 2 , in particular to the support member 14 of the spot welding device 2 .

[0092] The electrode holder 10 includes, for example, a holder body 26 configured for mounting the electrode holder 10 on the spot welding device 2 , in particular on the support member 14 of the spot welding device 2 , and two arms 28 , each arm 28 extending from the holder body 26 and supporting a corresponding spot welding electrode 12 .

[0093] Each arm 28 has, for example, a proximal end connected to the holder body 26 and a distal end supporting a corresponding spot welding electrode 12 .

[0094] The electrode holder 10 is, for example, "Y"-shaped, with the holder body 26 defining a leg of the "Y" and each arm 26 defining a respective branch of the "Y".

[0095] When provided, the fastening hole 24 is provided, for example, through the holder body 26 .

[0096] The spot welding gun 15 is preferably configured so that when the spot welding assembly 8 is mounted on the spot welding gun 15, the plane defined by the longitudinal axis A of the working surfaces 14 of the two spot welding electrodes 12 of one or each spot welding assembly 8 is substantially perpendicular to the pressing direction of the spot welding assembly 8 onto the welding location 4, 6.

[0097] In particular, when the spot welding gun 15 comprises support members 16 that are translationally movable relative to each other, the spot welding gun 15 is configured such that the plane defined by the longitudinal axes A of the two spot welding electrodes 12 of one or each spot welding assembly 8 is perpendicular to the direction of translation of the support members 16 relative to each other.

[0098] The electrode holder 10 is preferably electrically conductive. The electrode holder 10 is made of, for example, an electrically conductive material, preferably a metal.

[0099] The electrically conductive electrode holder 10 advantageously makes electrical contact with each spot welding electrode 12 held by the electrode holder 10 .

[0100] When the electrode holder 10 is mounted on the spot welding gun 15 , each spot welding electrode 12 is electrically connected to the electrical feed unit 20 via the electrode holder 10 .

[0101] like Figures 2 to 5 As shown, at least one or each spot welding electrode 12 of the spot welding assembly 8 is integrally formed together with the electrode holder 10 from a single piece of material.

[0102] In this case, when the spot welding electrode 12 is worn, the entire used spot welding assembly 8 needs to be replaced with a new spot welding assembly 8 .

[0103] like Figure 6 As shown, in a variation, the spot welding assembly 8 is configured so that each spot welding electrode 12 is removably mounted on an electrode holder 10 .

[0104] In one example, the spot welding assembly 8 includes a mounting assembly for removably mounting each spot welding electrode 12 on the electrode holder 10 .

[0105] The mounting assembly is configured, for example, for individually mounting at least one or each spot welding electrode 12 on the electrode holder 10 and / or for collectively mounting at least two spot welding electrodes 12 on the electrode holder 10 , the two spot welding electrodes 12 preferably being integrally formed from a single piece of material.

[0106] In one example, the spot welding electrodes 12 are separate, and the mounting assembly is configured for individually mounting each spot welding electrode 12 on the electrode holder 10 .

[0107] In another example, at least two spot welding electrodes 12 are integrally formed from a single piece of material, and the mounting assembly is configured to mount the spot welding electrodes 12 together on the electrode holder 10 .

[0108] The mounting assembly includes, for example, at least one mounting hole extending along a mounting axis and at least one mounting portion, each mounting portion being configured to be inserted into a corresponding mounting hole, each mounting hole being provided on one of the electrode holder 10 and the spot welding electrode 12, and the corresponding mounting portion being provided on the other.

[0109] Each mounting hole is, for example, tapered, and the corresponding mounting portion is tapered to complement the tapered shape of the mounting hole. With this configuration, the mounting portion inserted into the mounting hole can be fully adhered within the mounting hole during the welding operation, eliminating the need for additional retaining devices. Each tapered mounting hole defines a tapered seat.

[0110] Advantageously, the mounting assembly is configured such that each spot welding electrode 12 is mounted on the electrode holder 10 along the mounting axis by angular indexing and / or locking rotation relative to the electrode holder 10 about the mounting axis.

[0111] In one example, at least one mounting hole has a non-circular cross-section, and the corresponding mounting portion has a corresponding non-circular cross-section.

[0112] For example, at least one mounting hole has an oval cross-section and the corresponding mounting portion has a corresponding oval cross-section, and / or at least one mounting hole has a flat portion and the corresponding mounting portion has a corresponding flat portion.

[0113] Optionally or alternatively, at least one or each spot welding electrode 12 is mounted on the electrode holder 10 via two different mounting holes and two corresponding mounting portions.

[0114] The provision of two mounting holes and two corresponding mounting portions provides for angular indexing and / or rotational locking.

[0115] In this case, two mounting holes are provided on the electrode holder 10 and two mounting portions are provided on the spot welding electrode 12, or two mounting holes are provided on the spot welding electrode 12 and two mounting portions are provided on the electrode holder 10, or one mounting hole and one mounting portion are provided on the electrode holder 10 and corresponding mounting portions and mounting hole portions are provided on the spot welding electrode 12.

[0116] In one example, the mounting assembly includes two mounting holes and two corresponding mounting portions for individually mounting each spot welding electrode 12 to the electrode holder 10 .

[0117] In this case, two mounting holes are provided on the electrode holder 10, for example, and two mounting portions are provided on the spot welding electrode 12 separately mounted on the electrode holder 10, or two mounting holes are provided on the spot welding electrode 12 separately mounted on the electrode holder 10, for example, and two mounting portions are provided on the electrode holder 10, or one mounting hole and one mounting portion are provided on the electrode holder 10, and the corresponding mounting portion and mounting hole portion are provided on the spot welding electrode 12 separately mounted on the electrode holder 10.

[0118] In one example, since the two spot welding electrodes 12 are integrally manufactured from a single piece of material and are mounted together on the electrode holder 10 , the mounting assembly includes two mounting holes and two corresponding mounting portions.

[0119] In this case, two mounting holes are provided on the electrode holder 10, for example, and two mounting portions are provided on the spot welding electrodes 12 mounted together on the electrode holder 10, or two mounting holes are provided on two spot welding electrodes 12 mounted together on the electrode holder 10, for example, and two mounting portions are provided on the electrode holder 10, or one mounting hole and one mounting portion are provided on the electrode holder 10, and the corresponding mounting portions and mounting hole portions are provided on the spot welding electrodes 12 mounted together on the electrode holder 10.

[0120] In certain examples, the electrode holder 10 has a corresponding mounting hole 30 for each spot welding electrode 12 , and each spot welding electrode 12 includes a mounting portion 32 configured for insertion into the corresponding mounting hole 30 .

[0121] Each mounting hole 30 extends in a tapered shape, for example, along the mounting axis B, and the mounting portion of each spot welding electrode 12 has a tapered shape that complements the tapered shape of the mounting hole 30 .

[0122] Optionally, each mounting hole 30 has a hole flat portion 30A, and the corresponding mounting portion 32 has a partial flat portion 32A.

[0123] The removable spot welding electrode 12 makes it possible to replace a used spot welding electrode 12 of the spot welding assembly 8 without replacing the entire spot welding assembly 8 .

[0124] When the electrode holder 10 supports a plurality of spot welding electrodes 12 , the electrode holder 10 can be reused with the plurality of sets of spot welding electrodes 12 by replacing a worn set of spot welding electrodes 12 with a new one.

[0125] The present invention is not limited to the above-described examples and modifications, and other examples and modifications are conceivable.

[0126] The spot welding assembly 8 may include a single spot welding electrode 12. The single spot welding electrode 12 may be integrally formed with the electrode holder 10 in a single piece of material or may be removably mounted on the electrode holder 10.

[0127] The spot welding assembly 8 may include more than two spot welding electrodes 12 supported by the electrode holder 10 .

[0128] In a general manner, the spot welding assembly 8 comprises at least one spot welding electrode 12 , in particular one spot welding electrode 12 , two spot welding electrodes 12 or more than two spot welding electrodes 12 , which is supported by an electrode holder 10 .

[0129] exist Figures 1 to 5 In the example of FIG. 1 , each spot welding assembly has a spot welding electrode 12 , and each spot welding electrode 12 has a contoured working surface 14 .

[0130] Each spot welding assembly 8 having two spot welding electrodes does not necessarily have to include two spot welding electrodes 12 having contoured working surfaces 14 .

[0131] In another example, the spot welding assembly 8 includes one spot welding electrode 12 having a convex and contoured working surface 14, in particular a working surface 14 that is part of a cylindrical surface, preferably a cylindrical surface of circular cross-section, and another spot welding electrode having a working surface that is part of a spherical surface.

[0132] Similarly, in Figures 1 to 5 In the example of FIG. 4 , the spot welding device 2 comprises two spot welding assemblies 8 , each of which comprises at least one spot welding electrode 12 having a contoured working surface 14 .

[0133] In another example, the spot welding device 2 comprises: one spot welding assembly 8 having a spot welding electrode 12, the spot welding electrode 12 having a convex and contoured working surface 14, in particular a working surface 14 that is a portion of a cylindrical surface, preferably a portion of a cylindrical surface of a circular cross-section; and another spot welding assembly comprising at least one spot welding electrode, each spot welding electrode of the another spot welding assembly having a working surface that is a portion of a spherical surface.

[0134] like Figure 7 As shown, the spot welding electrode 12 having the working surface 14 profiled along the longitudinal axis A facilitates positioning of the spot welding electrode 12 relative to the convex surface 4A of the weld 4 so that the contact point M is precisely located on the weld 4 .

[0135] In fact, even if the position of the spot welding electrode 12 along the electrode axis A changes, the position of the contact point M on the convex surface 4 can remain the same.

[0136] In particular, when the convex surface 4A is contoured along the weld axis B, the spot welding electrode 12 can be oriented so that the longitudinal axis A and the weld axis B form a non-zero angle therebetween, whereby the working surface 14 and the convex surface 4A will contact at a contact point M of the convex surface 4, which remains the same even if the spot welding electrode 12 moves along the longitudinal axis A relative to the weld 4.

[0137] Furthermore, if the spot welding electrode 12 repeatedly performs welding operations, thereby forming a contact point M on the welding portion 4 that is precise but varies from welding operation to welding operation on the working surface 14 of the spot welding electrode 12 , the life of the spot welding electrode 12 can be increased.

[0138] Thanks to the invention, the spot welding electrode 12 has a convex working surface 14 profiled along the longitudinal axis A, making positioning of the spot welding electrode 12 easier and enabling an increase in the life of the spot welding electrode 12 .

[0139] Furthermore, the spot welding assembly 8 provided with the electrode holder 10 removably holding at least one spot welding electrode 12 makes it possible to replace a used spot welding electrode 12 with a new one and reuse the electrode holder 10 , which is more economical.

[0140] The spot welding electrode 12 , the spot welding assembly 8 comprising the spot welding electrode 12 or the spot welding device 2 comprising the spot welding assembly 8 can be used in particular in the field of nuclear technology, for example for welding metal parts of structures of nuclear fuel assemblies.

[0141] It can be used in various other technical fields to weld together any kind of metal parts. For example, it can be used in the automotive industry to weld parts of motor vehicle structures.

Claims

1. A spot welding electrode having a working surface (14) for contacting a part (4, 6) to be welded, wherein the working surface (14) is convex and profiled along a longitudinal axis (A).

2. The spot welding electrode according to claim 1, wherein the working surface (14) is a portion of a cylindrical surface centered about the electrode working surface axis (A).

3. The spot welding electrode according to claim 1 or 2, wherein the radius of curvature (R) of the working surface (14) is between 8 mm and 12 mm.

4. Spot welding electrode according to any of the preceding claims, wherein the working surface (14) has a width between 2 mm and 4 mm, the width being taken transversely between two side edges of the working surface (14) parallel to the longitudinal axis (A).

5. A spot welding assembly according to any one of the preceding claims, comprising an electrode holder (10) and at least one spot welding electrode (12) according to any one of the preceding claims.

6. The spot welding assembly according to claim 5, wherein each spot welding electrode (12) is removably attached to the electrode holder (10) to allow replacement of a used spot welding electrode (12) with a new spot welding electrode (12).

7. The spot welding assembly according to claim 5 or 6, wherein one of the electrode holder (10) and each spot welding electrode (12) has a mounting portion (32) configured to be inserted into the mounting hole (30) of the other of the electrode holder (10) and each spot welding electrode (12).

8. The spot welding assembly according to any one of claims 5 to 7, wherein each spot welding electrode (12) has a mounting portion (32) configured for insertion into a mounting hole (30) of the electrode holder (10).

9. The spot welding assembly according to any one of claims 5 to 8, comprising two spot welding electrodes (12).

10. The spot welding assembly according to claim 9, wherein the working surfaces (14) of the two spot welding electrodes (12) are profiled along coplanar respective longitudinal axes (A).

11. Spot welding assembly according to claim 9 or 10, wherein the longitudinal axes (A) of the two spot welding electrodes (12) define a non-zero angle therebetween.

12. Spot welding assembly according to any one of claims 9 to 11, wherein the longitudinal axes (A) of the two spot welding electrodes (12) define between them an angle of between 60° and 120°, in particular between 80° and 100°.

13. A spot welding device comprising two spot welding assemblies (8) and a spot welding gun (15), one or each spot welding assembly being a spot welding assembly according to any one of claims 5 to 12, the spot welding gun (15) being configured to support the two spot welding assemblies (8) and to generate an electric current between the two spot welding assemblies (8) when the two spot welding assemblies (8) are pressed onto parts (4, 6) to be welded together.

14. The spot welding device according to claim 13, wherein the spot welding gun (15) comprises two support members (16), each support member (16) being configured for supporting a respective one of the two spot welding assemblies (8), the two support members (16) being movable between a rest position in which the two spot welding assemblies (8) are moved apart and a welding position in which the two spot welding assemblies (8) are moved closer together to weld the two parts (4, 6).

15. Spot welding device according to claim 14, wherein the two support members (16) are translationally movable relative to each other, such as telescopically movable.

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