Process for welding heterogeneous sheets for motor vehicles

Abstract

The invention relates to a welding method for fixing a first part to a second part. The welding method comprises the steps: a) providing or producing (100) a first part with a first material; b) providing or producing (102) a second part with a metallic material different from the first material; c) drilling (104) the first part; d) placing (106) a retention pin in an orifice passing through the first part; e) arranging (108) an insulating sleeve in the orifice passing through the first part; f) electrically welding (110) the retention pin to the second part in order to connect the first part to the second part via the retention pin; the first part is then electrically insulated from the retention pin by the insulating sleeve. The method is applied to a motor vehicle structure. Figure to be published with the abstract: Figure 6

Description

Title of the invention: Method for welding heterogeneous sheets for motor vehicles

[0001] The invention relates to welds connecting parts made of different materials, and more precisely with distant melting temperatures. The invention relates to the fixing of sheets using welded retention pins. The invention relates to a welding method involving a retention pin in order to connect two parts made of materials of different natures. The invention also relates to an assembly, and to a motor vehicle with such an assembly.

[0002] A motor vehicle comprises a structure of complex shape, defining cavities and different profiles. In order to achieve these shapes according to predefined geometric tolerances, the structure requires the assembly of several sheets or sheets of material. Steel is widely used because of its mechanical strength and its ability to be shaped by stamping. The different stamped sheets are welded to each other.

[0003] Due to the electrification of motor vehicles, their mass frequently increases from 200 kg to 500 kg in order to carry enough electric batteries to extend their autonomy. To compensate for this increase in weight, the structure must be made lighter. This is possible by replacing certain steel sheets with aluminum sheets which still have to be welded to the preserved steel sheets. However, these materials have very different melting points, so that their mass welding as encountered in the automotive sector is not possible.

[0004] Steel pins can overcome this constraint. These steel pins have the same melting temperature as the steel sheets. They are inserted into holes in the aluminum sheets and then welded like electric welding spots. Furthermore, they are configured to ensure retention of the aluminum sheet they pass through.

[0005] The phenomena of galvanic corrosion are known. In the presence of a liquid phase forming an electrolyte, two materials with different electrical potentials generate a chemical oxidation-reduction reaction which physically consumes the material with the lowest electrical potential. In this case, the aluminum sheet dissolves around the pins which pass through it. Despite the pins being held in place by being welded to the steel sheet, the fixing function of the aluminum sheet is no longer ensured.

[0006] Document FR3097456B1 and document US20220355409A1 each present a method of assembling a sheet metal and an iron-based metal part comprising a step of punching through the sheet metal with a hollow cylinder made of electrically conductive metal, one end of which has a flare which abuts against the surface of the sheet metal once the through punching has been carried out, then a step of welding the hollow metal cylinder to the iron-based metal part by bringing a free end of the hollow metal cylinder opposite the flare into contact with the surface of the iron-based metal part and applying an electrical resistance welding electrode to the mouth of the flare.

[0007] The hollow welding pin comprises the first metal part, and a second metal part, the barrel of which is positioned externally. These parts are respectively made of low-alloy steel, and stainless steel. This solution results in a certain level of protection against galvanic corrosion. This solution remains expensive and heavy. There is also a need to further increase protection against the risk of galvanic corrosion.

[0008] The invention aims to address at least one of the problems or drawbacks encountered in the prior art. The invention aims to propose an alternative for protecting an assembly against corrosion. The invention aims to preserve a fixing by means of a welded retention pin between two heterogeneous parts. The invention also aims to optimize protection against galvanic corrosion, the mass and the cost of an assembly.

[0009] According to a first aspect, the invention proposes a welding method for fixing a first part to a second part via a retention pin; the welding method comprising the following steps: a) providing or producing a first part with a first material; b) providing or producing a second part with a metallic material different from the first material; d) placing a retention pin in an orifice passing through the first part; f) electrically welding the retention pin to the second part in order to bond the first part to the second part via the retention pin; remarkable in that before step f) electrically welding the welding method comprises a step: e) arranging an insulating sleeve in the orifice passing through the first part; in step f) electrically welding, the insulating sleeve surrounds the retention pin in order to electrically insulate the first part from the retention pin.

[0010] The invention makes it possible to weld materials of different natures, such as steel and aluminum, or aluminum and an organic matrix composite material. It makes it possible to optimize impact and fatigue resistance.

[0011] Preferably, the insulating sleeve comprises a ceramic material or a plastic material.

[0012] Preferably, the welding method further comprises a step c) drilling of the first part with the insulating sleeve; preferably, step c) drilling is a step of punching the first part with the insulating sleeve.

[0013] Preferably, before step d) placing the retention pin and / or before step e) arranging the insulating sleeve, said retention pin is in the insulating sleeve.

[0014] Preferably, step d) positioning the retaining pin and / or step e) arrangement of the insulating sleeve is carried out with a gripping tool comprising a bearing surface axially pushing the insulating sleeve and / or the gripping tool comprises a cylindrical holding surface holding the retaining pin.

[0015] Preferably, the first part comprises: an aluminum alloy, or plastic, or a composite material with fibers and a plastic resin; preferably, the metallic material comprises steel.

[0016] Preferably, in step e) arrangement, the insulating sleeve comprises a collar against the first part; before step f) electric welding, the collar surrounds the retention pin and / or a layer of adhesive is at an interface between the first part and the second part.

[0017] Preferably, the second part comprises a boss in contact with the first part; preferably, step b) supplying or producing the second part comprises producing the boss by stamping.

[0018] Preferably, the retention pin comprises a retention head.

[0019] Preferably, the retention pin comprises a cylindrical body with a first outside diameter, and a head with a second outside diameter greater than the first outside diameter.

[0020] Preferably, the insulating sleeve comprises an internal diameter equal to the first external diameter.

[0021] Preferably, the retention pin comprises the same metallic material as the second part.

[0022] Preferably, the retention pin is solid.

[0023] Preferably, the boss passes through the adhesive layer.

[0024] Preferably, before step f) electric welding, the first part and the second part are placed against each other and have a contact interface.

[0025] Preferably, step e) arrangement is a step of engaging the insulating sleeve.

[0026] Preferably, in step d) placing the retention pin and / or in step e) arranging the insulating sleeve, said retention pin is in the insulating sleeve.

[0027] Preferably, the welding method further comprises a step c) drilling the first part in order to form an orifice passing through said first part.

[0028] Preferably, in step f) electric welding, the electric welding is a electric resistance welding.

[0029] Preferably, the first material is a metal different from that of the second part.

[0030] According to another aspect, the invention provides an assembly comprising a first part with a first material and a second part with a metallic material different from the first material, the first part comprises a through-hole, the assembly further comprises a retention pin welded to the second part and extending into the through-hole of the first part in order to connect it to the second part; remarkable in that the assembly further comprises an insulating sleeve in the through-hole and surrounding the retention pin in order to electrically insulate the first part from the retention pin.

[0031] Preferably, the assembly results from the welding process according to the invention.

[0032] Preferably, the retention pin comprises a head diameter of between 9 mm and 19 mm.

[0033] According to another aspect, the invention proposes a motor vehicle comprising at least one assembly, remarkable in that the assembly is in accordance with the invention.

[0034] Preferably, the motor vehicle comprises an electric motor for driving the motor vehicle and an electric battery intended to power said electric drive motor.

[0035] Each characteristic introduced by the expression “preferably” given in relation to one of the aspects of the invention applies to all the other aspects of the invention.

[0036] The invention will be well understood and other aspects and advantages will appear clearly on reading the description which follows, given with reference to the figures appended and listed below.

[0037] [Fig.l] is a side view of a motor vehicle according to the invention.

[0038] [Fig.2] shows the gripping of a retention pin and an insulating sleeve by a gripping tool used during a welding process according to the invention.

[0039] [Fig. 3] illustrates the start of a step of drilling a first part with an insulating sleeve during a welding process according to the invention.

[0040] [Fig.4] illustrates a step of arranging an insulating sleeve in an orifice passing through a first sheet of a welding method according to the invention.

[0041] [Fig.5] represents an electric welding step of a welding method according to the invention.

[0042] [Fig.6] is a diagram of a welding process according to the invention.

[0043] In the following description, the term “understand” is synonymous with “include” and is not limiting in that it allows the presence of other elements in the vehicle. automobile, assembly or other steps in the welding process to which it relates. It is understood that the term "include" includes the terms "consist of". The terms "external" and "internal" will refer respectively to that which is oriented towards the outside of the vehicle and towards the inside of the vehicle.

[0044] In the present description, the term "longitudinal", the term "longitudinally", the term "transverse", and the term "transversely" are used according to the reference frame of the vehicle, in the mounting configuration. The term "longitudinal" corresponds to the main direction of movement of the vehicle. The term "transverse" corresponds to a direction perpendicular to the main direction of movement of the vehicle. The term "front" refers to the main direction of movement of the vehicle. The term "rear" designates the opposite of the front of the vehicle.

[0045] The X axis represents the longitudinal direction, the Y axis represents the transverse direction, and the Z axis represents the vertical direction of the motor vehicle. These three axes define a direct trihedron.

[0046] In the present description, the ranges of values ​​include the limits which delimit them.

[0047] In the present description, the equalities between the values ​​are not to be understood in the strict sense insofar as each equality authorizes a variation of at most 10%, preferably at most 5%, more preferably at most 2%, between these values.

[0048] In the present description, the term "vertical" and the term "horizontal" are not to be understood in the strict sense of the term. Indeed, they allow an inclination of at most 20°, preferably at most 10°, more preferably at most 5°, even more preferably at most 2°; compared to the strict sense of these terms.

[0049] Throughout the description, the different figures use the same reference signs to designate identical or similar entities.

[0050] Generally speaking, the invention proposes a method for welding heterogeneous sheets via at least one retention pin with an insulating spacer, preferably for producing a motor vehicle structure.

[0051] [Fig.l] represents a motor vehicle 10, according to one embodiment of the invention. The motor vehicle 10 comprises energy storage means and at least one motor (not shown) adapted to drive said motor vehicle 10. The motor is preferably an electric drive motor 14, and the storage means preferably comprise an electric battery 16 capable of driving the motor vehicle 10. The electric battery 16 has a mass of at least 250 kg, preferably at least 400 kg.

[0052] The motor vehicle 10 comprises a structure 12. The structure 12 forms an outer body, or even a main frame of the motor vehicle. The structure 12 delimits different compartments of the motor vehicle 10, including the passenger compartment. Structure 12 forms the roof and the underbody; it extends from the front to the rear of the motor vehicle. Structure 12 provides a mounting support for the powertrain, suspension systems, steering system, braking systems, and openings.

[0053] The structure 12 comprises at least one assembly 18 of sheets stamped and welded to each other. The sheets are metallic. According to one embodiment of the invention, the assembly 18 also comprises one or more parts produced by foundries. According to one embodiment of the invention, the assembly 18 comprises at least one part made of plastic material, for example a plastic matrix composite part. The composite part comprises reinforcing fibers, for example glass fibers or carbon fibers. The assembly 18 comprises two parts having two different materials, for example of different types and / or different natures, and which are fixed using retention pins.

[0054] The motor vehicle may, for example, be a private motor vehicle or a utility motor vehicle.

[0055] [Fig. 2] shows the gripping of an assembly including a retaining pin 20 and an insulating sleeve 22. Gripping is carried out using a gripping tool 24. The retaining pin 20 and the insulating sleeve 22 are here pre-assembled. Their tight fit allows for holding.

[0056] The retention pin 20 may be a welding pin. The retention pin 20 comprises a head 26 and a cylindrical body 28. The cylindrical body 28 is also called the foot of the pin. The head 26 is chamfered. An axial direction 30 is defined in relation to the retention pin 20. The axial direction 30 is along the axis of the cylindrical body 28. The retention pin 20 is made of a metallic material, for example steel.

[0057] The insulating sleeve 22 is generally an insulating tube. The insulating sleeve 22 may be an insulating sleeve. The insulating sleeve 22 forms an insulating sheath, such as a jacket or a sleeve, around the retaining pin. It is an electrically insulating sleeve. The insulating sleeve 22 comprises a tubular portion 32 and optionally a collar 34 at an axial end of the tubular portion 32. The tubular portion 32 is hollowed out, the cylindrical body 28 being partially housed therein.

[0058] The retention pin 20 is solid. The cylindrical body 28 has a first outside diameter, and the head 26 has a second outside diameter greater than the first outside diameter. The diameters are maximum diameters. The head 26 is chamfered. The insulating sleeve 22 has an inside diameter equal to the first outside diameter. This aspect optimizes mass and retention.

[0059] The gripping tool 24 comprises a bearing surface 36 capable of pushing the insulating sleeve 22; as well as a holding surface 38 capable of holding the retention pin. 20. The holding surface 38 is preferably perpendicular to the bearing surface 36. The bearing surface 36 is flat, and the holding surface 38 is cylindrical. The bearing surface 36 and the holding surface 38 are each split, and formed on two movable branches 40 of the gripping tool 24. The gripping tool 24 is able to rotate on itself. The movable branches 40 are able to move apart and come together in order to grasp and then release the retention pin 20.

[0060] [Fig. 3] shows a step of drilling a first part 42 with an insulating sleeve 22. The insulating sleeve 22 is held by the gripping tool 24 via a retention pin 20 which it surrounds. The gripping tool 24, the insulating sleeve 22 and the retention pin 20 may correspond to those shown in relation to [Fig. 2],

[0061] The gripping tool 24 is here in a closed configuration. Its movable branches 40 are tightened, and the holding surfaces 38 position the retention pin 20 relative to the first part 42.

[0062] The drilling is carried out by pressing the insulating sleeve 22 against the first part 42 via the gripping tool 24. The force is transmitted by the movable branches 40, at the level of the bearing surface 36 which is in abutment against the collar 34. It is understood that the extent of the collar 34 makes it possible to reduce the mechanical stress at its interface with the movable branches 40.

[0063] A stress concentration is observed at the level of the first part 42 in contact with the tubular portion 32. When the force exceeds the resistance of the first part 42, the latter is pierced and has a through orifice.

[0064] [Fig. 4] shows the result of a step of arranging an insulating sleeve 22 in a through-hole 48. The arrangement is a drilling which is carried out by punching using an insulating sleeve 22 pushed by a gripping tool 24. The gripping tool 24, the insulating sleeve 22 and the retention pin 20 correspond to those shown in relation to one of Figures 2 to 3. The first part 42 corresponds to that shown in relation to one of the preceding figures.

[0065] By increasing the pressing force 44 transmitted by the gripping tool 24, the insulating sleeve 22 punches the first part 42. It is remarkable that the drilling is carried out without mechanically stressing the retention pin 20. The latter is preserved.

[0066] A scrap 46 detaches from the first part 42. It comes out of the through-orifice 48. The through-orifice 48 forms a passage between the opposite faces of the first part 42. The scrap 46 is cut by the insulating sleeve 22. A die, with an orifice of complementary shape to the insulating sleeve 22, is arranged under the first part 42. The first part 42 rests horizontally on said die when the insulating sleeve 22 performs the punch function.

[0067] According to one embodiment of the invention, the drilling step and the arrangement step are carried out at the same time.

[0068] [Fig. 5] shows a welding step for fixing a first part 42 to a second part 50 via a retaining pin. The insulating sleeve 22, the retaining pin 20, the first part 42 correspond to those shown in relation to the previous figures. Beforehand, the gripping tool is released from the retaining pin.

[0069] At their interface, the first part 42 and the second part 50 are separated by a layer of adhesive 52. The adhesive layer 52 makes it possible to hold them temporarily. It is also capable of forming a waterproof barrier. Thus, it eliminates the possible presence of an electrolyte involved in galvanic corrosion. It is present before welding. The adhesive layer 52 is an adhesive film. It has a thickness of at most 1.00 mm; preferably at most 0.10 mm.

[0070] The retention pin 20 and the second part 50 comprise materials of the same type. They comprise metallic materials of the same nature. They may comprise similar alloys. By similar alloys is meant variations in shades remaining compatible for the purpose of their welding.

[0071] In order to maintain the spacing between the first part 42 and the second part 50, the latter has bosses 54. The adhesive layer 52 surrounds each boss 54 in order to insulate it in a sealed manner. In return, the presence of the bosses 54 makes it possible to maintain a minimum thickness for the adhesive layer 52.

[0072] The welding of the retention pin 20 on the adhesive layer 52 is carried out using a welding pliers 56. In a first step, the welding pliers 56 pushes the retention pin 20 into the insulating sleeve 22 up to the adhesive layer 52. The retention pin 20 enters and slides into the insulating sleeve 22. The welding pliers 56 exerts a force of between 300 N and 400 N. It will be deduced that the presence of the bosses 54 limits the crushing of the adhesive layer 52 despite the clamping force of the welding pliers 56.

[0073] An electric current is applied via the electrodes 58 of the welding clamp 56. The electrical resistance of the contact point increases the temperature. This electrical supply generates a melting of the metal at the tip of the retention pin 20 which is in contact with the adhesive layer 52, in particular through the adhesive layer 52. A welding point 60 is formed. The welding point 60 forms a continuity of material between the retention pin 20 and the adhesive layer 52 which become integral. The bosses 54 are at a distance from the welding point 60. Thus, during the temperature rise, the adhesive layer 52 in contact with the bosses 54 is preserved.

[0074] The weld point 60 is vertically at the level of the adhesive layer 52. It is surrounded by the insulating sleeve 22. The weld point 60 has a heat-affected zone. It has crystallographic heterogeneity at the interface of welding.

[0075] It is noted that the insulating sleeve 22 forms an electrical insulation barrier between the first part 42 and the second part 50. This aspect limits galvanic corrosion. Therefore, it is possible to fix a first aluminum part to a second steel part. The invention also limits the corrosion of parts having different electrical potentials.

[0076] According to one option, the insulating sleeve 22 forms a thermal protection of the first part 42 during welding. Thus, the first part may comprise a plastic material and the second part may comprise metal despite the difference in melting temperatures. The material of the insulating sleeve 22 comprises a thermal conduction coefficient lower than that of the retention pin.

[0077] In the present embodiment, the first part 42 and the second part 50 are sheets. They each have a constant thickness. Their thicknesses can be between 0.50 mm and 3.00 mm; preferably between 0.65 mm and 1.50 mm.

[0078] In the present embodiment illustrated in the preceding figures, the assembly 18 has two parts. However, the invention applies to an assembly with three or more parts. These parts are superimposed and linked by the retention pin 20. The first part receives a stack with the second part, a third part, and the following parts. The insulating sleeve 22 passes through the stack. For example, the first part is made of steel, the second part and the third part are made of aluminum. According to an alternative, the third part is made of steel, its face against the second aluminum part being covered with a layer of adhesive.

[0079] According to one embodiment of the invention, the insulating sleeve is hybrid. It comprises a tube made of ceramic material, and a collar with plastic, or vice versa. The plastic collar may be a plastic washer. The plastic washer surrounds the ceramic tube, or is axially against the ceramic tube.

[0080] The present embodiment describes a fixing of an assembly 18 with a pin-socket assembly. However, the invention applies to an assembly in which two parts are fixed by several pin-socket assemblies. It is interesting to note that the invention avoids the short-circuit effect, also designated by the English term “shunt”, when two parts are fixed by several retention pins close to each other.

[0081] [Fig.6] shows a diagram of a process for welding two parts of different materials, one of the parts having a metallic material. These two parts can form an assembly for a motor vehicle structure. The motor vehicle can correspond to that shown in relation to [Fig.l]. The assembly corresponds to one of the preceding figures.

[0082] The welding process comprising the following steps:

[0083] a) supply or production 100 of a first part with a first material;

[0084] b) supply or production 102 of a second part with a metallic material different from the first material;

[0085] c) drilling 104 of the first part with the insulating sleeve, in order to produce a through hole;

[0086] d) placing 106 of a retention pin in the orifice passing through the first part

[0087] e) arrangement 108 of an insulating sleeve in the hole passing through the first part;

[0088] f) electric welding 110 of the retention pin to the second part in order to bond the first part to the second part via the retention pin. The first part is then electrically insulated from the retention pin by the insulating sleeve that covers it.

[0089] Step b) providing or producing 102 the second part comprises producing a boss by stamping. A layer of adhesive is intended to form a contact interface with the first part. When the first part covers the second part, they remain at a distance from each other. This improves the insulation between these two parts via the layer of adhesive.

[0090] Step c) drilling 104 is a step of punching the first part by the insulating sleeve. According to an alternative of the invention, the through-hole is produced by molding, so that step c) drilling is optional. According to another alternative of the invention, the through-hole is produced by machining with a rotating tool, or by cutting during a stamping step. For example, the retention pin is inserted from one face of the first part, then the insulating sleeve is inserted from the other face, in an opposite direction.

[0091] Before step d) positioning 106 of the retaining pin and / or before step e) arrangement 108 of the insulating sleeve, said retaining pin is in the insulating sleeve. Step e) arrangement 108 is a step of inserting the insulating sleeve into the through-hole, while forming said through-hole. Step c) drilling 104 and step d) positioning 106 are carried out at the same time.

[0092] Step d) positioning 106 of the retention pin and step e) arrangement 108 of the insulating sleeve are carried out with a tool for gripping the retention pin. The gripping tool comprises a bearing surface pushing the insulating sleeve axially. The gripping tool also comprises a cylindrical holding surface holding the retention pin. The retention pin has a head diameter of between 9 mm and 19 mm. This range of diameters allows for positioning dispersions with the welding pliers, while controlling the compactness of the retention pin.

[0093] Steps d) installation 106 of the retention pin and step e) arrangement 108 of the insulating sleeve are produced at the same time. According to an alternative of the invention, step e) arrangement of the insulating sleeve is carried out before step d) installation of the retention pin.

[0094] According to an alternative of the invention, step d) installation is a step of roughing out the through-hole using the retention pin. Step e) arrangement is a step of finishing the through-hole.

[0095] In step e) arrangement 108, the insulating sleeve comprises a collar against the first part, the collar surrounds the retention pin. The collar is between the first part and the retention head of the retention pin. According to an alternative of the invention, the retention head comprises a washer made of insulating material against the first part. According to an alternative of the invention, the first part comprises a layer of insulation above; opposite the second part; the retention head being against said layer of insulation. Thus, the first part is electrically insulated from the retention pin, which avoids the risks of galvanic corrosion.

[0096] According to one embodiment of the invention, before step d) placing the retention pin 106 and step e) arrangement 108 of the insulating sleeve, and before the optional step c) drilling 104; the welding method comprises a step 112 of assembling the retention pin and the insulating sleeve. During the assembly step 112, the rod of the retention pin is inserted into the insulating sleeve. The retention pin comprises an axial direction along the through-hole and / or along the insulating sleeve. The welding method comprises a step of translating the retention pin in the insulating sleeve.

[0097] Before step f) electric welding 110 the first part and the second part are placed against each other and have a contact interface.

[0098] Before step f) electric welding 110, a layer of adhesive is at the interface of the first part and the second part. Preferably, the insulating sleeve is in contact with the layer of adhesive during said step f) electric welding 110. According to one embodiment, during step b) supply or production 102 of the second part, said second part is covered with the layer of adhesive.

[0099] According to an alternative of the invention, the adhesive layer is arranged against the first part during step a) supplying or producing the first part. According to another alternative of the invention, the adhesive layer is placed at the interface of the first part and the second part after steps a) supplying or producing the first part and b) supplying or producing the second part; and before step f) electric welding.

[0100] In step f) electric welding 110, an electric current is applied between the second part and the retention pin. Their contact being punctual, a rise in temperature is observed which causes their localized fusion, and therefore a fixing when The molten pool solidifies as it cools. The molten pool is surrounded by the insulating sleeve.

[0101] In step f) electric welding 110, the first part is electrically and thermally insulated from the retention pin by the insulating sleeve. The insulating sleeve is a piercing tool, and forms an intermediate part in the through hole. In addition to ensuring physical separation, the insulating sleeve plays an electrical insulating role, optionally accompanied by a thermal insulating role. Thus the invention manages to preserve the fixing formed by the retention pin. It preserves it during welding, and during the life of the vehicle. This makes it possible to resist shocks, and contributes to fatigue resistance.

[0102] According to a preferred embodiment, the insulating sleeve is made of a plastic or ceramic material.

[0103] The plastic material may comprise a thermoplastic material or a thermosetting material. The ceramic material may comprise alumina or silicon nitride.

[0104] The first part comprises at least 10% by weight of recycled material based on the total weight of said material; preferably from 10 to 80% by weight; more preferably from 20 to 60% by weight or from 30 to 40% by weight. The use of recycled material reduces the ecological footprint of the motor vehicle.

[0105] For example, the composite material comprises a matrix of a plastic material as described above with a reinforcement. For example, the reinforcement comprises glass or carbon fibers.

[0106] The first part comprises an aluminum alloy, copper, a composite material with fibers and a plastic resin. The fibers can be carbon or graphite fibers. Being electrically conductive, they are likely to participate in a galvanic corrosion phenomenon due to contact with a third metal part.

[0107] Preferably, the metallic material of the second part comprises steel. According to an alternative, it comprises aluminum and is different from the material of the first part. The retention pin is then made of aluminum.

[0108] The invention comprises the combination of all the embodiments illustrated by all the figures.

Claims

Claims

1. Welding method for fixing a first part (42) to a second part (50) via a retention pin (20); the welding method comprising the following steps: • a) providing or producing (100) a first part (42) with a first material; • b) providing or producing (102) a second part (50) with a metallic material different from the first material; • d) placing (106) a retention pin (20) in a through-hole (48) the first part (42); • f) electric welding (110) of the retention pin (20) to the second part (50) in order to connect the first part (42) to the second part (50) via the retention pin (20); characterized in that before step f) electric welding (110) the welding method comprises a step: • e) arrangement (108) of an insulating sleeve (22) in the through-hole (48) of the first part (42);in step f) electric welding (110), the insulating sleeve (22) surrounds the retention pin (20) in order to electrically insulate the first part (42) from the retention pin (20).;

2. Welding method according to claim 1, characterized in that the insulating sleeve (22) comprises a ceramic material or a plastic material.

3. Welding method according to one of claims 1 to 2, characterized in that the welding method further comprises a step c) piercing (104) of the first part (42) with the insulating sleeve (22); preferably, step c) piercing (104) is a step of punching the first part (42) by the insulating sleeve (22).

4. Welding method according to one of claims 1 to 3, characterized in that before step d) positioning (106) of the retaining pin (20) and / or before step e) arrangement (108) of the insulating sleeve (22), said retaining pin (20) is in the insulating sleeve (22).

5. Welding method according to claim 4, characterized in that step d) placing (106) the retention pin (20) and / or step e) arrangement (108) of the insulating sleeve (22) is produced with a gripping tool (24) comprising a bearing surface (36) axially pushing the insulating sleeve (22) and / or the gripping tool (24) comprises a cylindrical holding surface (38) holding the retention pin (20).

6. Welding method according to one of claims 1 to 5, characterized in that the first part (42) comprises: an aluminum alloy, or plastic, or a composite material with fibers and a plastic resin; preferably, the metallic material comprises steel.

7. Welding method according to one of claims 1 to 6, characterized in that in step e) arrangement (108), the insulating sleeve (22) comprises a collar (34) against the first part (42); before step f) electric welding (110), the collar (34) surrounds the retention pin (20) and / or a layer of adhesive (52) is at an interface between the first part (42) and the second part (50).

8. Welding method according to one of claims 1 to 7, characterized in that the second part (50) comprises a boss (54) in contact with the first part (42); preferably, step b) supplying or producing (102) the second part (50) comprises producing the boss (54) by stamping.

9. Assembly (18) comprising a first part (42) with a first material and a second part (50) with a metallic material different from the first material, the first part (42) comprises a through-hole (48), the assembly (18) further comprises a retention pin (20) welded to the second part (50) and extending into the through-hole (48) of the first part (42) in order to connect it to the second part (50); characterized in that the assembly (18) further comprises an insulating sleeve (22) in the through-hole (48) and surrounding the retention pin (20) in order to electrically insulate the first part (42) from the retention pin (20); preferably, the assembly (18) is produced by the welding method according to one of claims 1 to 8; and the retention pin (20) has a head diameter of between 9 mm and 19 mm.

10. Motor vehicle (10) comprising at least one assembly (18), characterized in that the assembly (18) is in accordance with claim 9; preferably the motor vehicle (10) comprises an electric drive motor (14) of the motor vehicle (10) and a electric battery (16) intended to power said electric drive motor (14).

Images