Specimen support for misalignment testing in spot welding

Abstract

The invention relates to a spot welding system for joining a first sheet (20) to a second sheet (22) via a welding pin inserted in the second sheet. The welding system comprises: a frame, a clamp with a first electrode and a second electrode, and a positioning support (18) for holding the first and second sheets. The positioning support (18) includes first means for positioning the first sheet (20) in a first position; and second positioning means comprising at least one first positioning orifice (48) configured to position the second sheet (22) in a second position, and at least one second positioning orifice (52) configured to position the second sheet at a distance from the second position. Figure to be published with the abbreviation: Figure 3

Description

Title of the invention: Specimen support for misalignment testing in spot welding

[0001] The invention relates to the field of automotive vehicle assembly by spot welding. The invention relates in particular to welding tests of two metal parts of an automotive structure, such as sheet metal parts. More specifically, the invention relates to a welding system with eccentricity adjustment between the electrodes and a sheet metal welding pin.

[0002] It is known to construct structures such as vehicle bodies by assembling various metal parts, such as steel sheets, using resistance electric spot welding. More than 80% of motor vehicle bodies are thus assembled by spot welding. To do this, at least two metal parts are held together by means of a clamp that applies concentrated pressure. The temperature is raised by passing an electric current until the material melts at the contact area between the clamp's electrodes. This technique, called spot welding, is therefore dependent on the resistivity of the materials, the thickness of the joint, and the diameter of the electrodes forming the clamp.

[0003] To compensate for the increased weight of motor vehicles, particularly battery-electric vehicles, their structure must be lightened. This is possible by replacing some steel sheets with aluminum sheets, which must then be welded to the remaining steel sheets. However, these materials have very different melting points, making mass production welding, as encountered in the automotive industry, complex. Metal welding pins can overcome this constraint. These metal pins have the same melting point as the steel sheets. They are inserted into aluminum sheets and then welded in the same way as electric spot welds. Furthermore, they are designed to hold the aluminum sheet through which they pass.

[0004] Spot welding devices are configured to be mounted on industrial robots capable of welding the various metal components of a vehicle on an assembly line. However, the position of a set of parts to be welded on an assembly line can vary by a few millimeters from one case to another. A weld pin may therefore not be located exactly on the axis formed by the two welding electrodes. The mechanical strength of a weld point can be affected if this misalignment exceeds a certain value. said value varies according to the nature of the materials to be assembled and the type of welding pin used.

[0005] Trials and tests are carried out during the research and development stage to establish tolerance thresholds for the misalignment of the welding pins relative to the electrode axis. These tests consist of measuring the tensile strength of specimens made of two materials joined in a cross shape by a centered weld point. They employ a spot welding device with a welding pin, the position of which on a specimen to be tested being precisely determined in order to investigate the weld strength under different misalignment positions.

[0006] Document JP5813443 B2 presents spot welding equipment allowing precise control of the electrode position along the axis formed by said electrodes. However, it does not allow modulation of the position in a plane perpendicular to said axis.

[0007] The invention aims to address at least one of the problems or drawbacks encountered in the prior art. In particular, the invention aims to provide a system for precisely varying the positioning of a welding pin relative to the axis formed by the welding electrodes on a weld strength test specimen. The invention aims to improve electrical welding tests using welding pins.

[0008] According to a first aspect, the invention proposes a spot welding system, the welding system being intended to weld a first sheet to a second sheet via a welding pin inserted in the second sheet; the welding system comprising: a clamp with a first electrode intended to be in electrical contact with the first sheet, a second electrode intended to be in electrical contact with the welding pin in order to weld it to the first sheet through the second sheet; a positioning support intended to hold the first sheet and the second sheet, the positioning support comprising a general plane, a passage intended to be traversed by one of the first electrodes and the second electrode; remarkable in that the positioning support comprises first means for positioning the first sheet according to a first position;second positioning means comprising at least a first positioning orifice configured to position the second sheet in a second position, at least a second positioning orifice configured to position the second sheet at a distance from the second position.

[0009] It will be understood that the invention provides a welding test specimen support allowing the creation and experimental variation of an offset between the axis of the welding electrodes and the welding pin, in order to obtain welding test specimens to analyze the strength of welds obtained according to the chosen offset. The invention makes it possible to control the offset in order to perform comparisons.

[0010] Document FR2998820 B1 describes a counter electrode designed to cooperate with an electrode of a spot welding device, the electrode and counter electrode extending along a welding axis, the counter electrode being mobile between different weld portions to compensate for wear on the latter. However, this document does not present any relevant solution regarding the variation of the positioning of the welding axis relative to the spot weld.

[0011] Preferably, the second positioning means comprise at least one row of positioning ports including at least one first positioning port and at least one second positioning port; preferably, each row of positioning ports comprises at least five positioning ports.

[0012] Preferably, the second positioning means comprise an adjustment groove with an adjustment direction, the at least one first positioning orifice being at a distance from the at least one second positioning orifice along the adjustment direction.

[0013] Preferably, the second positioning means comprise a positioning rod inserted into one of the first positioning orifice and the second positioning orifice, and a movable adjustment stop attached to the adjustment groove.

[0014] Preferably, the passage is adjusted to the first electrode in order to maintain the positioning support on the first electrode; preferably, the welding system comprises a frame, the first electrode being a fixed electrode, and the second electrode is mobile relative to the first electrode.

[0015] Preferably, the first electrode comprises an outer diameter between 16 mm and 20 mm; and / or the passage comprises an inner diameter between 16 mm and 20 mm.

[0016] Preferably, the positioning support includes a receiving surface for the first sheet, the first electrode includes a contact pad protruding from the receiving surface; preferably, the contact pad protrudes from the receiving surface by 0.50 mm to 1.00 mm.

[0017] Preferably, the positioning ports are identical.

[0018] Preferably, the first positioning means comprise at least one positioning couple, each positioning couple comprises a stop axis and a groove opposite to the stop axis with respect to the centering orifice.

[0019] Preferably, the passage is a centering orifice and / or a central passage.

[0020] Preferably, the centering hole is intended to be aligned with the welding pin.

[0021] Preferably, the second position is centered with respect to the centering orifice.

[0022] Preferably, the positioning support includes a center at the level of the passage.

[0023] Preferably, the first electrode is a lower electrode, and the second electrode is a higher electrode.

[0024] Preferably, the welding pin is driven into the second sheet.

[0025] According to another aspect, the invention proposes a spot welding system, the welding system being intended to weld a first sheet to a second sheet via a welding pin inserted in the second sheet; the welding system comprising: a clamp with a first electrode intended to be in electrical contact with the first sheet, a second electrode intended to be in electrical contact with the welding pin in order to weld it to the first sheet through the second sheet; a positioning support intended to hold the first sheet and the second sheet, the positioning support comprising a general plane, a passage intended to be traversed by one of the first electrodes and the second electrode; notable in that the positioning support comprises first locking holes configured to position the first sheet in a first position;at least one first positioning orifice configured to position the second sheet metal in a second position, and means for adjusting the position of the second sheet metal configured to position the second sheet metal at a distance from the second position.

[0026] According to another aspect, the invention proposes a method for welding a first sheet to a second sheet with a welding pin through the second sheet, by means of a welding system; remarkable in that the welding system conforms to the invention, the welding method comprising the following steps: a) supplying or making a first sheet and a second sheet which is traversed by a welding pin; b) placing the first sheet and the second sheet in the welding system; c) positioning relative to the positioning support of the first sheet by the first positioning means and positioning relative to the positioning support of the second sheet by the second positioning means; d) welding the second sheet to the first sheet by application of an electric current; preferably, the first sheet comprises steel and the second sheet comprises aluminum.

[0027] Preferably, the welding process further includes a step e) changing the configuration of the second positioning means.

[0028] Preferably, the first sheet and the second sheet are rectangular.

[0029] Preferably, the first sheet and the second sheet comprise a length between 110 mm and 130 mm; and / or a width between 35 mm and 55 mm.

[0030] Each feature introduced by the expression "preferably" given in relation to one of the aspects of the invention applies to all other aspects of the invention.

[0031] The invention will be well understood and other aspects and advantages will become clear upon reading the following description, given with reference to the attached figures listed below.

[0032] Fig. 1 represents a cross-sectional view of a spot welding system according to the invention.

[0033] Fig. 2 is a perspective view of a positioning support for a spot welding system according to the invention.

[0034] Fig. 3 shows a top view of a positioning support for a spot welding system according to the invention.

[0035] Fig. 4 is a diagram of a welding process with a welding system according to the invention.

[0036] In the following description, the term "include" is synonymous with "include" and is not limiting in that it permits the presence of other elements in the welding system or other steps in the process to which it relates. It is understood that the term "include" includes the terms "consist of." The terms "external" and "internal" shall respectively designate what is oriented towards the outside of the vehicle and towards the inside of the vehicle.

[0037] In this description, the ranges of values ​​include the bounds that delimit them.

[0038] In the present description, the equality between the values ​​is not to be understood in the strict sense insofar as each equality allows a variation of at most 10%, preferably at most 5%, more preferably at most 2%, between these values.

[0039] In this description, the terms "vertical" and "horizontal" are not to be understood in their strict sense. Indeed, they allow an inclination of at most 20°, preferably at most 10°, more preferably at most 5°, and even more preferably at most 2°, relative to the strict meaning of these terms. In this description, the term "position" is defined by the centering and orientation of the sheet metal.

[0040] In this description, the technical characteristics are defined in the system mounting configuration, unless otherwise explicitly stated.

[0041] Throughout the description, the different figures use the same reference signs to designate identical or similar entities.

[0042] Fig. 1 represents a cross-sectional view of a 10 spot welding system according to the invention.

[0043] The welding system 10 comprises a frame (not shown for clarity) supporting a welding clamp 12. The welding clamp 12 is movable relative to the frame. The welding clamp 12 has a first electrode 14, a second electrode 16, and a positioning support 18. The first electrode 14 is a fixed electrode, and the second electrode 16 is movable relative to the first electrode 14. For example, the first electrode 14 is a lower electrode, and the second electrode 16 is an upper electrode. According to an alternative embodiment of the invention, the first and second electrodes are vertically at the same level.

[0044] The positioning support 18 is traversed by a passage 90. The passage 90 is traversed by the first electrode. The passage 90 may be a centering orifice 34, into which the first electrode 14 is inserted. A diameter of the centering orifice 34 is adjusted to the first electrode 14 to allow the centering of said first electrode 14 along a first axis 36. This adjustment ensures the stability of the positioning support 18 on the first electrode 14 when it is inserted therein.

[0045] The positioning support 18 includes a receiving surface 70 of a first sheet 20. The first electrode 14 includes a contact pad 72 projecting above the positioning support 18. The contact pad 72 projects from the receiving surface 70 by 0.50 to 1.00 mm.

[0046] The welding system 10 is capable of joining together at least one first sheet 20 with a second sheet 22 by means of a welding pin 24. The first sheet 20 comprises a first material; preferably, this first material comprises metal, for example, steel. The second sheet 22 comprises a second material, preferably different from the first material. This second material comprises metal, for example, aluminum. The second sheet 22 is optionally thicker than the first sheet 20.

[0047] The second plate 22 is traversed by the welding pin 24. Said welding pin 24 may be a retaining pin. The welding pin 24 comprises a head 32 and a cylindrical body 28. The cylindrical body 28 is also called the foot of the pin. An axis, called the second axis 30, is defined in relation to the welding pin 24. The second axis 30 is along the axis of the cylindrical body 28.

[0048] The welding pin 24 is made of a metallic material, for example, steel. The welding pin 24 is in contact with the first plate 20. The welding pin 24 and the first plate 20 are made of the same type of material. They are metallic materials of the same nature. They may be made of similar alloys. Similar alloys are understood to mean variations in grades that remain compatible for welding.

[0049] The welding of the welding pin 24 on the first sheet 20 is carried out using the welding clamp 12. Initially, the welding clamp 12 pushes the welding pin 24 through the second sheet 22 to the first sheet 20.

[0050] The first electrode 14 is in electrical contact with the first sheet 20; the second electrode 16 is in electrical contact with the welding pin 24. An electric current is applied via the first and second electrodes 14 and 16 of the welding clamp 12. The electrical resistance of the contact point increases the temperature. This electrical supply generates a melting of the metal at the tip of the welding pin 24, which is in contact with the first sheet 20. A weld point 38 is formed. Upon cooling, this weld point 38 forms a continuous material between the welding pin 24 and the first sheet 20, which become bonded. The weld point 38 is aligned with the first electrode 14 and the second electrode 16, that is, along the first axis 36. The weld point 38 has a diameter between 1.00 mm and 7.00 mm; preferably between 2.00 mm and 6.00 mm.

[0051] Preferably, the centering hole 34 is intended to be aligned with the welding pin 24. In the ideal theoretical case, the welding pin 24 is aligned with the first electrode 14 and the second electrode 16. The first axis 36 coincides with the second axis 30; the mechanical strength of the weld is maximized. On an assembly line, however, it is known that this alignment varies randomly. The first axis 36 and the second axis 30 may be parallel but not coincident, with an offset 40. In practice, the offset 40 varies from 1 mm to 4 mm.

[0052] Depending on the value of the misalignment 40, the mechanical strength of the assembly formed by the first sheet 20 and the second sheet 22 varies. If the misalignment 40 exceeds a limit value, the strength of an off-center weld may fall below a tolerance threshold, and the quality of the assembly is compromised. The welding system 10 performs spot welds for which the misalignment 40 is controlled. The welding system 10 allows weld test specimens 86 to be joined between sheets made of different materials and of varying thicknesses in order to subsequently investigate the weld strength as a function of the value of the misalignment 40. The welding system 10 makes it possible to determine the limit value of the misalignment 40 for a given assembly.

[0053] In the present embodiment, the assembly comprises two sheets. However, the invention applies to an assembly of three or more sheets. These sheets are stacked and joined by a weld comprising the welding pin 24. The first sheet is stacked with the second sheet and a third, intermediate sheet. The pin of Welding 24 passes through the second sheet of the stack; the weld creates a weld point 38 between the weld point 24 and the intermediate sheet, which is electrically welded to the first sheet. For example, the first sheet and the intermediate sheet are made of steel, and the second sheet is made of aluminum.

[0054] Figure 2 shows a perspective view of a positioning support 18 for a spot welding system according to the invention. The welding system may correspond to that shown in relation to Figure 1.

[0055] The positioning support 18 serves to precisely impose and maintain the respective positions of the first and second plates. This positioning support 18 comprises a general plane 42 and a passage 90 such as a centering orifice 34. The passage 90 is intended to be traversed by the first electrode. The passage 90 is a central passage on the general plane 42. The positioning support 18 includes a center at the centering orifice 34.

[0056] According to an alternative embodiment of the invention, the passage 90 comprises a slot extending from an edge of the positioning support to the middle thereof. This configuration facilitates the entry and exit of the first electrode in the passage.

[0057] The first electrode can be of various types. It can include an active face of different diameters; for example, the first electrode is flat, frustoconical, spherical, or domed. The first electrode has an outer diameter between 16 mm and 20 mm. It includes a cylindrical bearing surface defining its outer diameter. The centering orifice 34, and therefore the positioning support 18, is adapted to a given type of first electrode. The centering orifice 34 has an inner diameter between 16 mm and 20 mm.

[0058] The positioning support 18 includes first positioning means 44 for the first sheet metal in a first position relative to said positioning support 18. These first positioning means 44 include at least two first locking holes 58 configured to lock the first sheet metal in two perpendicular directions, and at least two locking grooves 60 positioned opposite each other at a distance from the first locking holes 58. A locking groove 60 and a first locking hole 58 extending from the locking groove form a positioning pair. The first positioning means 44 include at least one positioning pair; preferably at least three positioning pairs.

[0059] The positioning support 18 includes second positioning means 46. The second positioning means 46 include at least a first positioning orifice 48 configured to position the second sheet metal in a second position relative to the positioning support 18.

[0060] The second positioning means 46 comprise at least one row of positioning holes 50 including at least one first positioning hole 48 and at least one second positioning hole 52. The second sheet metal is positioned at a distance from the second position, i.e., at a third position. The second sheet metal can then be fixed in at least four alternative positions to the second position, at a distance from said second position along an adjustment direction 56. Preferably, each row of positioning holes 50 comprises at least five positioning holes spaced apart from each other along the adjustment direction 56, and transversely to the adjustment direction 56.

[0061] The positioning support 18 comprises two rows of positioning holes 50, transversely spaced and facing each other. Each row of positioning holes 50 comprises at least one first positioning hole 48 and at least one second positioning hole 52. The positioning holes are identical to each other. The rows of positioning holes 50 are symmetrical on either side of the centering hole 34.

[0062] The second positioning means 46 include an adjustment groove 54 defining the adjustment direction 56. At least one first positioning orifice 48 is at a distance from at least one second positioning orifice 52 along the adjustment direction 56. In this case, the second positioning means 46 include two parallel adjustment grooves 54. Each adjustment groove 54 is longer than the locking grooves 60. Each second positioning orifice 52, particularly when combined with an adjustment groove 54, forms position adjustment means.

[0063] The second positioning means 46 also include at least one second locking orifice 62 and, opposite it, at a distance, at least one second locking groove 64 in a direction perpendicular to the adjustment direction 56. The second locking orifice 62 and the second locking groove 64 are configured to allow sheet metal to be positioned in a single position. Each adjustment groove 54 is longer than the second locking groove 64.

[0064] The positioning support 18 includes openings 68 distributed in the general plane 42 and passing through said general plane 42. They serve to lighten the positioning support 18.

[0065] According to an alternative of the invention, the positioning support comprises a positioning rail for the second sheet; the first positioning orifice being at a distance from the second positioning orifice along said positioning rail.

[0066] The positioning support 18 comprises a material having electrical non-conductivity and heat resistance properties. Preferably, it includes medium density fibers (designated by the English acronym MDF for Medium Density Fiberboard) or high density fibers (designated by the English acronym HDF for High Density Fiberboard).

[0067] Figure 3 shows a plan view of a positioning support 18 for a spot welding system according to the invention. The welding system may correspond to that shown in relation to one of Figures 1 to 2. In the present illustration, the positioning support 18 and the sheets are placed horizontally. However, they could be arranged vertically.

[0068] The positioning support 18 is shown with the first sheet 20 in the first position against the positioning support 18, and the second sheet 22 in a second position; all the way above.

[0069] The first and second sheets are rectangular; preferably, the first and second sheets have a length between 110 mm and 130 mm; and / or a width between 35 mm and 55 mm. Their thicknesses are between 0.50 mm and 5.00 mm; preferably between 1.50 mm and 3.50 mm.

[0070] First locking stops 74 (represented by crosses) are inserted into each first locking hole 58. The first locking stops 74 include, for example, locking rods that are inserted into the first locking holes 58. The first locking stops 74 protrude from the receiving surface 70 and lock the first sheet 20 in two perpendicular directions. At least two locking grooves 60 are positioned opposite each other at a distance from the locking axes 60 so that the first sheet 20 is positioned between a first locking hole 58 and a corresponding locking groove 60. A first movable stop 76 is associated with each locking groove 60 and locks the first sheet 20 against the first locking stops 74 in the first locking holes 58. Each first movable stop 76 slides in its associated locking groove 60. After contact with the first plate 20, its position is locked.

[0071] The second plate 22 is placed on the first plate 20, perpendicular to said first plate 20. Positioning rods 78 are inserted into the first or second positioning holes 48 and 52 and protrude from the receiving surface 70; they protrude. By convention, the holes occupied by a positioning rod 78 are represented with a cross. In this case, the positioning rods 78 are in the second positioning holes 52. The second plate 22 is held in the second position against the positioning rods 78 in the adjustment direction 56 by the support of an adjustment stop 80 which slides in the adjustment groove 54.

[0072] The second sheet metal 22 is held in the direction perpendicular to the adjustment direction 56 by bearing against a second locking stop 82 inserted in each second locking orifice 62. The second locking stop 82 protrudes from the receiving surface 70. A second movable stop 84 is associated with each second locking groove 64 and locks the second sheet metal 22 against the second locking stop 82. At least one second movable stop 84 slides in the second locking groove 64.

[0073] At least one row of positioning holes 50 allows the second sheet metal 22 to be fixed, i.e., immobilized, in a second position defined by the selected positioning hole. For example, in the embodiment shown in [Fig. 3], the position of the first positioning hole 48 varies by 4 mm with the position of the second positioning hole 52, in the adjustment direction 56. The second position of the second sheet metal 22 includes a first alternative using the first positioning hole 48 and a second alternative using the second positioning hole 52. For example, each row of positioning holes 50 includes at least five positioning holes located transversely and longitudinally at a distance from each other; the second position then has at least four alternative second positions.Preferably, the alternative second positions vary by 1 mm in the adjustment direction 56. The offset between successive alternative second positions is 1 mm.

[0074] The position of the second axis 30 is defined by the second position of the second sheet 22 and therefore varies according to the positioning orifice used.

[0075] Conversely, the initial position of the first plate 20 is constant; therefore, the position of the centering hole 34 and the first axis 36 is also fixed. It is thus possible to check the alignment of the first axis 36 with the second axis 30, along the adjustment direction 56. The offset 40 is a function of this alignment. The offset 40 is in the general plane.

[0076] The spot welding system, thanks to the positioning support 18, makes it possible to produce weld test pieces 86 in which the offset 40 is precisely defined, in order to analyze the resistance properties of said welds according to the offset 40 used.

[0077] Figure 4 shows a diagram of a welding process for joining a first sheet to a second sheet with a weld pin through the second sheet. The weld is performed using a welding system. The welding system may correspond to the one shown in relation to one of Figures 1 to 3. The test specimen and the sheets correspond to one of the preceding figures.

[0078] The welding process comprises the following steps:

[0079] a) supply or production 100 of a first sheet and a second sheet which is crossed by a welding pin;

[0080] b) placement 102 of the first sheet and the second sheet in the welding system;

[0081] c) positioning 104 relative to the positioning support of the first sheet metal by the first positioning means and positioning relative to the positioning support of the second sheet metal by the second positioning means;

[0082] d) welding 106 of the second sheet to the first sheet by applying an electric current between the electrodes of the welding system

[0083] The welded test specimen to be analyzed is obtained in step d) welding 106 of the second sheet to the first sheet. It complies with a predefined offset.

[0084] The first sheet comprises steel and the second sheet comprises aluminum. The welding pin comprises a different material than the second sheet. It comprises steel.

[0085] Step b) setup 102 and c) positioning 104 can be carried out simultaneously.

[0086] The welding process further comprises a step:

[0087] e) change of configuration 108 of the second positioning means.

[0088] The production of a new weld test piece, different from the first test piece by the alignment of the first axis with the second axis is then carried out by repeating the steps b) placement 102 to d) welding 106 of the second sheet to the first sheet.

[0089] Before step d) welding 106 of the second sheet to the first sheet, said first and second sheets are stacked against each other and present a contact interface.

[0090] In step d) welding 106 of the second sheet to the first sheet, an electric current is applied between the second piece and the welding pin. Since their contact is point-like, a temperature rise is observed, causing localized melting and thus fixation as the weld pool solidifies upon cooling.

[0091] The invention comprises the combination of all the embodiments illustrated by all the figures.

[0092] Figures 2 and 3 are isometric views. They each respect a specific scale, real angles and real proportions.

Claims

Demands

1. Spot welding system (10), the welding system (10) being intended to weld a first sheet (20) to a second sheet (22) via a welding pin (24) inserted in the second sheet (22); the welding system (10) comprising: a welding clamp (12) with a first electrode (14) intended to be in electrical contact with the first sheet (20), a second electrode (16) intended to be in electrical contact with the welding pin (24) in order to weld it to the first sheet (20) through the second sheet (22); a positioning support (18) intended to hold the first sheet (20) and the second sheet (22), the positioning support (18) comprising a general plane (42), a passage (90) intended to be traversed by one of the first electrode (14) and the second electrode (16); characterized in that the positioning support (18) includes first positioning means (44) of the first sheet (20) according to a first position;second positioning means (46) comprising at least a first positioning orifice (48) configured to position the second sheet (22) according to a second position, at least a second positioning orifice (52) configured to position the second sheet (22) at a distance from the second position.;

2. Welding system (10) according to claim 1, characterized in that the second positioning means (46) comprise at least one row of positioning orifices (50) including at least one first positioning orifice (48) and at least one second positioning orifice (52); preferably, each row of positioning orifices (50) comprises at least five positioning orifices.

3. Welding system (10) according to any one of claims 1 to 2, characterized in that the second positioning means (46) comprise an adjustment groove (54) with an adjustment direction (56), the at least one first positioning orifice (48) being at a distance from the at least one second positioning orifice (52) along the adjustment direction (56).

4. Welding system (10) according to claim 3, characterized in that the second positioning means (46) comprise a positioning rod (78) inserted into one of the first orifice positioning (48) and second positioning orifice (52), and an adjustment stop (80) attached to the adjustment groove (54).

5. Welding system (10) according to any one of the preceding claims, characterized in that the passage (90) is adjusted to the first electrode (14) in order to maintain the positioning support (18) on the first electrode (14); preferably, the welding system (10) comprises a frame, the first electrode (14) being a fixed electrode, and the second electrode (16) is movable relative to the first electrode (14).

6. Welding system (10) according to any one of the preceding claims, characterized in that the first electrode (14) comprises an outside diameter between 16 mm and 20 mm; and / or the passage (90) comprises an inside diameter between 16 mm and 20 mm.

7. Welding system (10) according to any one of the preceding claims, characterized in that the positioning support (18) comprises a receiving surface (70) for the first sheet (20), the first electrode (14) comprises a contact pad (72) projecting from the receiving surface (70); preferably, the contact pad (72) projects from the receiving surface (70) by 0.50 mm to 1.00 mm.

8. A welding method of a first sheet (20) to a second sheet (22) with a welding pin (24) through the second sheet (22), by a welding system (10); characterized in that the welding system (10) conforms to any one of claims 1 to 7, the welding method comprises the following steps: a) supplying or producing (100) a first sheet (20) and a second sheet (22) which is traversed by a welding pin (24); b) placing (102) the first sheet (20) and the second sheet (22) in the welding system (10); c) positioning (104) relative to the positioning support of the first sheet (20) by the first positioning means (44) and positioning relative to the positioning support of the second sheet (22) by the second positioning means (46); d) welding (106) of the second sheet (22) to the first sheet (20) by application of an electric current;Preferably, the first sheet (20) comprises steel and the second sheet (22) comprises aluminum.

9. Welding process according to claim 8, characterized in that the welding process further comprises a step e) change of configuration (108) of the second positioning means (46).

10. A welding method according to any one of claims 8 to 9, characterized in that the first plate (20) and the second plate (22) are rectangular; preferably, the first plate (20) and the second plate (22) comprise a length between 110 mm and 130 mm; and / or a width between 35 mm and 55 mm.

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