Method for the mechanical fastening of a connecting element, connecting system and motor vehicle

Abstract

Method for mechanically fastening a connecting element (1) to a workpiece (30), wherein the procedure comprises the following steps: - Creating a recess (50), in particular a blind hole or a through hole, in a workpiece (30) using a laser beam (60), - Heating the workpiece (30) at least in the area of ​​the recess (50) by means of the laser beam (60), so that softened material or a material melt (70) is formed in the recess (50), - Inserting a pin-like section (20) of a connecting element (1), in particular a U-shaped clamp (10), into the recess (50), - Formation of a welded or soldered joint between the pin-like section (20) of the fastener (1) and the workpiece (30) in the recess (50), wherein at least intermittently, the heating of the workpiece (30) is carried out simultaneously with the creation of the recess (50) in order to form the softened material or the material melt (70).

Description

[0001] The present invention relates to a method for mechanically fastening a connecting element to a workpiece by means of a welded or soldered joint, a connecting system, in particular for carrying out the method according to the invention, and a motor vehicle with a workpiece and a connecting element connected to the workpiece according to the invention.

[0002] In manufacturing technology, welding and brazing processes are used to permanently join certain materials. Welding is defined as the permanent, material-bonded joining of workpieces using heat and / or pressure (DIN 1910-100), while brazing refers to thermal processes for joining workpieces in which a liquid phase is created, for example, by melting a solder material. The difference between welding and brazing lies in the fact that in welding, the melting or liquidus temperature of the materials being welded is exceeded, resulting in the formation of a melt, whereas in brazing, only the liquidus temperature of the solder material is exceeded.

[0003] Laser welding processes are known from the prior art in which the heat required for welding is provided by irradiation with a laser beam. The laser beam is typically focused on the workpieces to be welded to enable effective heat transfer. Depending on the laser beam intensity, a vapor capillary (also known as a keyhole) filled with metal vapor and / or partially ionized metal vapor forms in the molten material of the workpiece exposed to the laser beam along the longitudinal direction of the laser beam. This so-called deep penetration welding effect effectively conducts heat deep into the workpiece, thereby melting the material to its core.

[0004] Laser-based drilling methods are also known from the prior art, in which a recess, in particular a blind hole or through hole, is formed by locally limited melting of the material as a result of heating by the laser beam.

[0005] From the document DE 10 2008 058 917 A1, a joining method for overlapping materials is also known, in which the materials are made plastically deformable by heating using a laser beam and are then joined together by introducing a joining element under mechanical deformation of the materials.

[0006] In modern manufacturing technology, it is often necessary to join different materials together, for example steel, aluminum, plastics and fiber-reinforced plastics.

[0007] However, welding and soldering processes are generally only of limited use for joining different materials, as some technological and / or material-related problems can arise when using these processes due to their different physical and chemical properties.

[0008] Therefore, there is a need to develop new methods for permanently joining, especially dissimilar materials. The aim is to achieve the highest possible joint strength with minimal material usage and cost-effective production. In particular, the formation of intermetallic phases at a welded or brazed joint, which can impair the quality of the joint, must be prevented or minimized.

[0009] The invention is therefore based on the objective of providing an effective, widely applicable and cost-effective method for the mechanical fastening of a connecting element to a workpiece, in particular for joining different materials, a fastening system for the mechanical fastening of a connecting element to a workpiece and a motor vehicle with a workpiece and a connecting element connected to the workpiece according to the invention, which meet the aforementioned objectives.

[0010] This problem is solved by the inventive method according to claim 1, the inventive connection system according to claim 8, and the inventive motor vehicle according to claim 10. Advantageous embodiments of the inventive method are specified in dependent claims 2 to 7, and an advantageous embodiment of the connection system is specified in dependent claim 9.

[0011] A first aspect of the present invention relates to a method for mechanically fastening a connecting element to a workpiece, wherein the method comprises the following steps: - Creating a recess, in particular a blind hole or a through hole, in a workpiece using a laser beam, - Heating the workpiece, at least in the area of ​​the recess, using the laser beam, so that softened material or a molten material is formed in the recess, - Inserting a pin-like section of a fastener, in particular a U-shaped clamp, into the recess, - Creating a welded or soldered joint between the pin-like section of the fastener and the workpiece in the recess, where, at least in certain periods of time, the workpiece is heated simultaneously with the creation of the recess in order to form the softened material or the molten material.

[0012] The recess is created in the longitudinal direction of the laser beam, particularly using a laser drilling process. This process generates a so-called vaporization capillary (also known as a "keyhole"), the properties of which depend on the specific material and the laser beam intensity. The depth of the recess increases with increasing laser beam intensity (due to increasing laser power) and / or with the irradiation time.

[0013] The laser beam is focused onto the workpiece, particularly by means of a converging lens. The focus diameter of the laser beam at the point of impact on the workpiece is specifically adapted to the maximum diameter of the pin-like section to be inserted, preferably larger than the maximum diameter of the pin-like section, so that the resulting recess is of a suitable size, allowing the pin-like section to be inserted into the recess without collision. Depending on the properties of the laser beam, sufficiently large recesses can also be produced with smaller focus diameters.

[0014] The heat introduced into the workpiece by the laser beam serves to soften or melt material within the workpiece, particularly in the case of a weld, and / or an additional material, such as solder, which is fed into the recess. The solder can, for example, be a component of the pin-shaped section inserted into the recess. The intensity of the laser beam is set sufficiently high to melt or soften the respective materials within a short time.

[0015] The method is therefore advantageously implemented in such a way that heat is transferred from the area of ​​the recess in the workpiece heated by means of the laser beam to the pin-like section after the pin-like section has been inserted into the recess.

[0016] The softened material or melt can be the material of the heated workpiece, and / or material of an additional material, such as solder, which is then transformed into a slurry state or a melt by the supplied heat.

[0017] In particular, the pin-like section of the fastener can consist of or incorporate such an additive material, for example, in the form of a solder coating. In this case, a soldered connection is created between the pin-like section and the workpiece. This is also possible if the pin-like section and the workpiece are made of different materials.

[0018] In contrast, a welded connection between the pin-like section and the workpiece can be made provided that the pin-like section and the workpiece are made of weldable materials.

[0019] According to the invention, the term "simultaneous heating in stages" means that heating is carried out during the creation of the recess, whereby the heating phase is not limited to the time required to create the recess, but can also last longer. In particular, if an additive material, e.g., a solder material, is added later, the creation of the recess may only overlap with the formation of the softened material or the material melt in stages, because the additive material can only be softened or melted after its addition.

[0020] One advantage of the described process is the ability to simultaneously create a recess in a workpiece and supply the heat required for welding or soldering in a single step. This saves energy costs and reduces the production time of the corresponding welded or soldered joint. Another advantage is the suitability of the process for joining different materials, especially different metals, such as steel and aluminum, or metals and plastics (including fiber-reinforced plastics), which are difficult to join using conventional methods. Materials with surface coatings, particularly plastics, paints, or adhesives, can also be easily joined, as the laser beam advantageously vaporizes these coatings in the area of ​​the recess.The process can also be applied to variable material thicknesses and multi-layer connections.

[0021] According to one embodiment of the method, a mechanical force is exerted on the fastener during the production of the welded or brazed joint, that is, during the cooling of the workpiece and / or the pin-like section. This force can be transmitted, for example, by means of a feeding and / or holding tool that holds the fastener and / or inserts the pin-like section of the fastener into the recess. In particular, the force applied when inserting the pin-like section into the recess is maintained until a sufficiently strong welded or brazed joint has formed between the pin-like section and the workpiece.

[0022] The pin-like section of the fastener has a cylindrical surface and is bounded by an end face in the longitudinal direction of the pin-like section. The end face is located at the end of the pin-like section that is first inserted into the recess. Heat transfer from the workpiece to the pin-like section melts or softens the pin-like section, particularly at its end face and / or at least a portion of its cylindrical surface.

[0023] In one embodiment of the method, the pin-like section is inserted into the recess to its maximum depth, so that the hot material of the workpiece located at the bottom of the recess can contribute to direct heat transfer to the pin-like section, e.g., by forming a welded or brazed joint between the bottom of the recess and the end face of the pin-like section. Alternatively, however, only partial insertion of the pin-like section into the recess is also provided, so that a gap exists between the bottom of the recess and the end face of the pin-like section, in which case heat is transferred directly only to the outer surface of the pin-like section.

[0024] In the inventive method, the amount of heat transferred can be adjusted by means of the laser intensity so that only a thin layer of the pin-like section is melted or softened. This has the advantage that a welded or soldered joint can be formed with low energy consumption and thus at reduced costs.

[0025] In one embodiment, the pin-like section comprises an additive material, in particular a solder material, which can be melted or softened by means of the laser beam, so that the pin-like section can be attached to the workpiece by means of a welding or soldering joint between the additive material and the workpiece. The additive material can be in the form of a coating on the pin-like section.

[0026] In another embodiment, the solder material comprises a copper-silicon compound, for example CuSi3, with a silicon content by weight of 2% to 4.5%, in particular 2.2% to 3.5%.

[0027] With a silicon content in the range of 2.2% to 3.5% by weight, the solder material is particularly liquid due to its melting properties.

[0028] In another embodiment, the solder material contains zinc with a weight fraction of 0.1% to 2%, in particular 0.25% to 0.5%.

[0029] The pin-like section of the fastener may have a point on its end face. This facilitates the insertion of the pin-like section into the recess through self-centering.

[0030] In one embodiment, the recess or the pin-like section of the fastener is preheated before the recess is heated and before the fastener is inserted into the recess, e.g., using a laser beam. Additionally, the fastener or the workpiece can also be heated after the pin-like section has been inserted into the recess, for example, using a laser beam, to facilitate welding or soldering.

[0031] In a further embodiment, the inventive method for mechanically fastening a connecting element to a workpiece comprises a method for manufacturing a connecting element.

[0032] This has the advantage that the shape and dimensions of the fastener can be adapted to the parameters of the workpieces to be joined, in particular the thickness and material properties of the workpieces.

[0033] According to a further embodiment of the method, by inserting the pin-like section into the recess, at least a part of the molten material or the softened material is displaced from the recess.

[0034] This has the advantage that intermetallic phases that form, which generally have a detrimental effect on joint strength, are forced out or flushed out. In this process, impurities in the molten material, which can lead to poor weldability, are also advantageously removed during melt pool cleaning.

[0035] In particular, the insertion of the pin-like section into the recess is carried out at high speed, so that the softened material or the molten material has not yet cooled down when the pin-like section enters the recess and / or the molten material is displaced so quickly by the rapid insertion of the pin-like section that a particularly effective melt bath cleaning is achieved.

[0036] The insertion of the pin-like section into the recess occurs particularly quickly after the recess has been created using the laser beam. This makes the melt pool cleaning process more effective, as the shorter time interval results in the formation of fewer intermetallic phases.

[0037] According to one embodiment of the method, the connecting element or a holding tool holding the connecting element interrupts the laser beam during the insertion of the pin-like section into the recess.

[0038] Such shading of the laser beam by the fastener or holding tool has the advantage that the laser beam does not need to be switched off in coordination with the feed of the fastener or shaded by a separate device. This allows the process to be carried out without a corresponding control device and thus saves costs.

[0039] In the described method, the pin-like section can in particular be heated by means of the laser beam during the interruption of the laser beam if this is advantageous for the welding or soldering process.

[0040] The interruption of the laser beam can optionally be detected with a suitable measuring device, for example, using optical coherence tomography. In particular, the detection of the laser beam interruption generates a signal to switch off or deflect the laser beam. This prevents damage to the fastener or the holding tool that secures the fastener, especially damage caused by the laser beam.

[0041] According to a further embodiment of the method, the fastener has a pressure section which runs at an angle of 45° to 135°, in particular 90°, to the pin-like section of the fastener, wherein the fastener is connected to the workpiece in such a way that the pressure section bears against a surface of a workpiece under a compressive preload.

[0042] The workpiece against which the pressure section rests can be a first workpiece to which the pin-like section is attached by welding or soldering, or, in particular, a second workpiece which is pressed against the first workpiece by the pressure section in such a way that a positive and non-positive connection between the two workpieces is achieved with the connecting element. The pin-like section does not necessarily have to be welded or soldered to the second workpiece.

[0043] This embodiment has the advantage that the clamping section increases the stability of the workpiece connection through its compressive preload. Furthermore, the contraction of the fastener during cooling as the weld or brazed joint forms has a beneficial effect, further increasing the compressive preload and consequently enhancing the effectiveness of the resulting frictional connection.

[0044] In particular, the fastener is designed as a U-shaped clamp, the central region of which forms the contact section that rests against the surface of a workpiece. The invention is not limited to the design of the central region of the U-clamp as a contact section.

[0045] When using a U-shaped clamp, the U-shaped clamp has two pin-like sections, wherein in a method according to the invention for attaching the U-shaped clamp to a workpiece by means of the laser beam two recesses are created in the workpiece at a corresponding distance, and wherein both pin-like sections of the U-shaped clamp are inserted into a respective recess.

[0046] In this process, the two cutouts can be created simultaneously using two laser beams. These two laser beams can be generated, for example, by two separate laser sources. Alternatively, a laser beam generated by a single laser source can be split into two partial beams, for example, using a beam splitter. Another alternative involves creating the two cutouts sequentially, particularly in rapid succession, using a single laser beam, with relative movement between the laser beam and the workpiece. This can be achieved by moving the laser source and / or the workpiece.

[0047] The simultaneous or rapidly successive creation of multiple recesses using one or more laser beams is not limited to the use of U-shaped clamps, but can also be used to attach multiple fasteners, each with only one pin-like section, to the workpiece simultaneously or in rapid succession.

[0048] The two pin-like sections of the U-shaped clamp are mechanically connected by a bridging section, which can run at an angle of 90° to the pin-like sections. The bridging section can also be designed as a clamping section.

[0049] The use of a U-shaped clamp in the inventive method has the advantage that the bridging section connected to both pin-like sections holds two welded or soldered joints together, thus providing additional stability to the connection achieved by means of the U-shaped clamp. Furthermore, by controlling the amount of heat transferred via the laser intensity, it is possible with the inventive method to melt or soften only a thin layer of the pin-like section, and still achieve high connection stability by using a clamp with two pin-like sections.

[0050] According to a further embodiment, the bridging section, particularly in a configuration of the bridging section as a pressure section, is curved so that it forms a bending spring which acts towards the surface of the workpiece and thus exerts a permanent mechanical pressure force on the workpiece under preload.

[0051] According to a further embodiment, a first workpiece and a second workpiece are positioned adjacent to each other or at a small distance from each other on a separation plane, wherein the first workpiece has a first recess into which the pin-like section is to be inserted, and wherein the second workpiece has a second recess, and the pin-like section is inserted at an angle of 30° to 150°, in particular 90°, to the separation plane through the second recess of the second workpiece into the first recess of the first workpiece.

[0052] In such an overlapping connection, the second workpiece in particular either has a pre-formed through-hole which is brought into alignment with the recess of the first workpiece when the pin-like section is inserted, or in the course of the inventive method, the through-hole of the second workpiece and subsequently the recess of the first workpiece are formed by means of the laser beam.

[0053] In particular, in this alternative method, a first workpiece and a second workpiece are arranged one above the other, wherein first a through hole of the second workpiece arranged above the recess of the first workpiece is penetrated by the pin-like section of the connecting element and then the pin-like section is inserted into the recess of the first workpiece.

[0054] According to a further embodiment of the method, a first workpiece and a second workpiece are positioned adjacent to each other or at a small distance from each other on a parting plane, wherein the first workpiece has a first recess into which the pin-like section is to be inserted, and wherein the second workpiece has a second recess, wherein the first and the second recess are each formed as grooves on the respective surfaces of the first and the second workpiece, and wherein the first and the second recess are arranged in the relative position of the workpieces such that the first and the second recess together form a common recess, in particular a blind hole or through hole, arranged in the parting plane.The pin-like section is inserted into the common recess, so that the pin-like section is welded or soldered to the two workpieces on opposite sides of its outer surface.

[0055] In such a so-called butt joint, a mechanical connection between the workpieces is formed, in particular by means of the pin-like section of the fastener, at equal lengths on opposite sides of the workpieces.

[0056] According to a further embodiment of the method, a first workpiece and a second workpiece are positioned adjacent to each other or at a small distance from each other at a parting plane, wherein the first workpiece has a first recess into which the pin-like section is to be inserted, and wherein the second workpiece has a second recess. The first recess and the second recess are each designed as a blind hole or a through hole. The fastener has a first pin-like section and a second pin-like section, wherein the first pin-like section is inserted into the first recess and wherein the second pin-like section is inserted into the second recess.

[0057] In particular, the connecting element is designed as a U-shaped clamp with two pin-shaped sections arranged essentially parallel to each other, wherein the pin-shaped sections are each inserted into a recess in one of the two workpieces.

[0058] In particular, during at least part of the method according to the invention, a mechanical force is exerted perpendicular to the separation plane between the first workpiece and the second workpiece by a suitable holding tool, so that the first and the second workpiece are pressed together.

[0059] In the described joining methods between a first workpiece and a second workpiece, at least one welded or soldered joint is created between the pin-like section of the connecting element and the first workpiece.

[0060] In addition, in certain embodiments of the method, the second workpiece can also be connected to the connecting element by means of a welded or soldered connection.

[0061] A positive-locking and force-locking connection is created between the first and second workpieces using the connecting element. In particular, the second recess of the second workpiece and the first recess of the first workpiece can be created in a single operation using a laser beam.

[0062] Alternatively, the first recess of the first workpiece and the second recess of the second workpiece can be produced separately and aligned before the fastener is inserted. For this embodiment, it is advantageous if the fastener, with its contact section, bears against the surface of the second workpiece under a compressive preload.

[0063] The described method has the advantage that several workpieces made of different materials can be mechanically joined together, which cannot be joined or can only be joined inadequately using conventional methods, for example, those that are difficult to weld. This is made possible by indirectly joining the workpieces mechanically using the fastener, whereby one workpiece is welded or brazed to the fastener and the other workpiece is mechanically attached by the fastener.

[0064] For example, the inventive method can be used to join steel and aluminum or metals and plastics (including fiber-reinforced plastics). Furthermore, several plastic workpieces can be joined together, particularly by means of a connecting element whose pin-like section is made of plastic, whereby the intensity, duration, and / or wavelength of the laser beam can be reduced accordingly due to the lower melting point of plastics compared to metals. A welding process between a thermoset material and a thermoplastic material is also possible with a corresponding method.

[0065] According to another embodiment of the method, the welded or soldered connection is only made between a lateral surface of the pin-shaped section and the workpiece.

[0066] This is particularly possible if the pin-shaped section consists of a solder material or has solder material on its outer surface, e.g. coated with solder material which is softened or melted by the heating of the workpiece and thereby creates the soldered connection with the workpiece.

[0067] A connection using the cylindrical surface has the advantage that, on the one hand, the pin-like section does not have to be completely inserted into the recess, since the end face of the pin-like section does not have to be connected to the bottom of the recess in the workpiece, and on the other hand, it is also possible to attach the connecting element to the workpiece if the recess in the workpiece is designed as a through hole.

[0068] Alternatively or additionally, a welded or soldered connection can also be made between the end face of the pin-shaped section and the workpiece.

[0069] According to a further embodiment of the method, when creating the recess using the laser beam, the laser power is adjusted in a burn-in phase such that the depth of the recess increases in the longitudinal direction of the laser beam, and when creating the recess, upon reaching a defined value of a physical parameter, in particular the depth of the recess, the laser power is adjusted in a heating phase such that a smaller increase in depth per unit of time occurs compared to the burn-in phase, wherein during the heating phase the material surrounding the recess is heated using the laser beam.

[0070] This means that when the defined value of the physical parameter is reached, the curing phase ends and the heating phase begins. Naturally, the material surrounding the recess is also heated during the curing phase.

[0071] Controlling a physical parameter has the advantage of allowing the creation of recesses with highly reproducible depths, enabling optimal process control and the production of connections with consistently reproducible strength and dimensions. Suitable physical parameters include, for example, the depth of the recess, the temperature in the recess area, and / or the amount of heat introduced into the recess.

[0072] In particular, during the heating phase there is no significant increase in the depth of the recess, but possibly a widening of the recess.

[0073] The laser power is maintained at a constant first power value during the burn-in phase and at a constant second power value during the heating phase, with the first power value being higher than the second. Depending on the specific power values ​​and materials used, this power profile leads, in particular, to a linear increase in the depth of the recess during the burn-in phase, while the depth of the recess remains almost constant during the heating phase.

[0074] In particular, the depth of the created recess can be measured using optical coherence tomography (OCT). During the recess creation process, the workpiece is coupled into the measuring arm of an interferometer, so that the depth of the recess can be determined by the interference signal of a measuring laser beam reflected from the bottom of the workpiece with a reference beam running in a reference arm of the interferometer.

[0075] The device, particularly for performing optical coherence tomography, is connected to a control unit for controlling the laser intensity of the laser beam creating the recess, so that the laser intensity can be changed by means of the control unit depending on the measured depth of the recess. Additionally or alternatively, the control unit can be configured to control a feeding device for feeding a connecting element and / or inserting the pin-like section of the connecting element into the recess, so that, by means of a signal from the control unit, particularly when a defined depth of the recess is reached, a connecting element can be positioned above the recess and / or the connecting element can be inserted into the recess.

[0076] Based on the measured physical parameter, a signal can be generated after a defined time of laser irradiation to supply the fastener and / or insert the pin-like section of the fastener into the recess.

[0077] According to a further embodiment of the method, a connecting element, in particular a U-shaped clamp, is produced in a coupled process step immediately before the connecting element is inserted into the recess.

[0078] This has the advantage that the fasteners required for forming the welded or soldered joint can be produced directly in the same process, thereby saving costs, particularly for the storage and transport of the fasteners. Furthermore, the dimensions of the pin-like sections of the fasteners can be easily adapted to the workpieces to be joined.

[0079] According to a further embodiment, the connecting element is produced by cutting a wire section from a wire and bending the wire section, in particular into a U-shape. This process can be carried out automatically.

[0080] One advantage of this method is the ability to easily and cost-effectively produce suitable fasteners from a suitable wire.

[0081] In particular, the wire incorporates an additive material, such as a solder material, that can be melted or softened by a laser beam. The wire can be coated, or in particular encased, with the additive material. Alternatively, the wire can be made of a readily meltable or softenable material. These configurations have the advantage that, in the case of a soldering process, no additive material needs to be separately introduced into the recess of the workpiece to form the solder joint.

[0082] According to a further embodiment, the cutting process of the wire creates a point on an end face of the pin-like section of the connecting element. This facilitates the insertion of the pin-like section into the recess by means of self-centering.

[0083] According to a second aspect of the invention, a connection system for the mechanical fastening of a connecting element to a workpiece is provided. The connection system comprises a laser source for generating a laser beam, wherein the laser beam is configured to create a recess, in particular a blind hole or through hole, in a workpiece and to heat the workpiece, at least in the area of ​​the recess, such that softened material or a molten material can be formed in the recess.

[0084] Furthermore, the connection system has a device for inserting connecting elements into a workpiece, which is designed to insert a pin-like section of a connecting element, in particular a pin-like section of a U-shaped clamp, into the recess created by means of the laser beam in such a way that a welding or soldering connection between the pin-like section and the workpiece in the recess can be produced.

[0085] The connection system also includes a control device designed to adjust the laser power during the creation of the recess using the laser beam in a burn-in phase such that the depth of the recess increases in the longitudinal direction of the laser beam, and upon reaching a defined value of a physical parameter, in particular the depth of the recess, to adjust the laser power in a heating phase such that a smaller increase in depth per unit of time occurs compared to the burn-in phase, while simultaneously heating the material surrounding the recess using the laser beam.

[0086] Suitable physical parameters include, for example, the depth of the created recess, the temperature in the area of ​​the recess and / or the amount of heat introduced into the recess.

[0087] Using such a control device, the process parameters can be optimally controlled based on physical measurement parameters, thus enabling high reproducibility of the strength and dimensioning of the produced connections.

[0088] According to one embodiment, the connection system includes a measuring device for measuring a physical parameter of the recess, in particular by means of optical coherence tomography (OCT), wherein the measuring device is connected to a control device for controlling the laser intensity of the laser beam creating the recess, so that the laser intensity can be changed by means of the control device depending on the measured depth of the recess. In particular, the measuring device is a device for performing optical coherence tomography (OCT), comprising a measuring laser source for generating a measuring laser beam, a measuring arm and a reference arm, wherein the depth of the recess formed in the workpiece can be determined by means of the interference signal between the measuring arm and the reference arm.

[0089] According to a further embodiment, the control device is connected to a feeding device for feeding a connecting element and / or inserting the pin-like section of the connecting element into the recess, so that by means of a signal from the control device, in particular when a defined depth of the recess is reached, a connecting element can be positioned above the recess and / or the connecting element can be inserted into the recess.

[0090] According to one embodiment, the connection system includes a bending and cutting device for producing a connector with a pin-like section. The bending and cutting device is configured to produce a U-shaped clamp. The bending and cutting device comprises a punch and a die, the punch having a bending segment and a cutting segment. The bending and cutting device is configured to cut a wire segment from a wire by means of the cutting segment and, in the same stroke, to deform the wire segment by means of the bending segment by means of the bending segment, through a movement of the punch relative to the die.

[0091] This has the advantage that the fasteners required for forming the welded or soldered joint can be produced directly in the same process, thereby saving costs, particularly for the storage and transport of the fasteners. The described device allows for the simple and cost-effective production of fasteners from a single wire.

[0092] The punch has, in particular, a first contact surface and the die has a second contact surface, wherein the first contact surface and the second contact surface are shaped complementarily to each other, such that a wire section arranged between the first contact surface and the second contact surface assumes a shape which substantially corresponds to the shape of the contact surfaces by means of a movement of the punch relative to the die through bending of the wire section.

[0093] In particular, the first contact surface has a depression and the second contact surface has a projection shaped complementarily to the depression, wherein, for example, the depression and the projection are each U-shaped, so that a U-shaped clamp can be produced from the wire using the bending and cutting device.

[0094] The bending and cutting device has a counter blade, wherein the cutting segment is arranged to move in relation to the counter blade when the punch moves relative to the die, such that a wire positioned between the cutting segment and the counter blade can be cut by means of the cutting segment and the counter blade.

[0095] Either the punch or the die can be designed to be movable, so that the movement of the punch relative to the die can be achieved either by a movement of the punch or by a movement of the die.

[0096] The cutting segment can be mechanically connected to the punch or designed as an integral part of the punch.

[0097] The punch or die is mechanically connected, in particular, to a piston-cylinder unit, so that a movement of the piston can be transferred to the punch or die.

[0098] In particular, the bending and cutting device has an adjustment device for changing a stop position, so that the stop position can be changed in such a way that connecting elements with pin-like sections of different defined lengths can be produced using the bending and cutting device.

[0099] In particular, the wire incorporates an additive material, such as a solder material, that can be melted or softened by the laser beam of the joining system. The wire can be coated, for example, with the additive material. Alternatively, the wire can be made of a material that can be melted or softened by the laser beam. These configurations have the advantage that, in the case of a soldering process, no additive material needs to be separately introduced into the recess of the workpiece to form the solder joint.

[0100] According to another embodiment, the cutting segment is designed to create a tip of the pin-like section of the connecting element by means of the cutting process.

[0101] The joining system may include a transport device designed to feed connecting elements produced by the bending and cutting device to the device for inserting connecting elements into a workpiece.

[0102] In particular, the bending and cutting device has an ejector for ejecting the produced fastener, wherein the ejector is configured to feed produced fasteners to the transport device.

[0103] According to a further embodiment, the connecting system includes a wire conveyor, in particular a two-roller conveyor, for feeding the wire to the bending and cutting device. The wire conveyor allows the required wire to be unwound from a wire spool and transported to the bending and cutting device.

[0104] According to a third aspect of the invention, a motor vehicle, in particular a passenger car, is provided. The motor vehicle comprises at least one workpiece and a connecting means, wherein the connecting means is mechanically attached to the workpiece by means of a welded or brazed joint produced by a method according to the first aspect of the invention.

[0105] The workpiece in question is, in particular, a body panel of a motor vehicle. In the construction of motor vehicles, it is often necessary to join workpieces made of different materials, which cannot be welded using conventional methods. The method according to the invention is particularly advantageous for this purpose.

[0106] The invention will be explained below with reference to the exemplary embodiments shown in the accompanying drawings.

[0107] They show Fig. 1: a schematic representation of the method according to the invention, Fig. 2: a schematic representation of a partial step of the method according to the invention, Fig. 3: a schematic representation of a welded or soldered joint between a U-shaped clamp with a curved pressure section and a workpiece, Fig. 4a-c: different views of an end-seam welded or soldered joint according to the invention, Fig. 5: a schematic representation of a welded or soldered joint between a U-shaped clamp with a straight clamping section and a workpiece, Fig. 6: a further schematic representation of a partial step of the method according to the invention, Fig. 7: an arrangement for the simultaneous generation of two laser beams and Fig. 8: a device for manufacturing U-shaped clamps.

[0108] To describe an embodiment of the method according to the invention, reference is first made to the Fig. 1.

[0109] This shows a sectional view of a first workpiece 31 and a second workpiece 32, wherein the workpieces 31, 32 are arranged layer by layer. Furthermore, a laser beam 60 focused by means of a converging lens 62 is shown, which travels along a laser beam longitudinal direction 61 perpendicular to the surface of the second workpiece 32. Fig. Figure 1 also shows a recess 50 created by means of the laser beam 60, wherein the representations of the recess 50 from left to right represent individual states of a temporal progression of the creation of the recess 50 by means of a laser drilling process.

[0110] In the upper part of the Fig. Figure 1 shows a time / power diagram with a time axis representing time t and an ordinate representing the power P of the laser beam 60. A time / depth diagram is also shown with a time axis representing time, which has a scale identical to that of the time / power diagram, and an ordinate representing the depth T of the recess 50.

[0111] The process begins at time t0 with the activation of the laser beam 60. Between times t0 and t1, the power P remains constant. At time t1, the power P is abruptly reduced to a lower value and remains constant until time t2. The area under the shown time / power curve corresponds to the heat Q transferable by the laser beam 60 between times t0 and t2.

[0112] Between times t0 and t1, the depth T of the recess 50 increases linearly as a result of the constantly high power P of the laser beam 60. Due to the decrease in power P at time t1, the depth T of the recess 50 remains almost constant between times t1 and t2, with heat being transferred to the recess 50 by means of the laser beam 60.

[0113] The representations of recess 50 are each assigned to a point in time during the laser drilling process, corresponding to the point on the time axis shown in the representation of the Fig. 1 is arranged perpendicularly above the respective representation of the recess 50.

[0114] The depth T of the recess 50, which is assigned to time t2, is shown as an example in the representation of the recess 50, and increases during the course of the laser drilling process, so that the recess 50 present at time t2 extends through the second workpiece 32 into the first workpiece 31, whereby the recess 50 is formed by a through hole of the second workpiece 32 and an adjacent blind hole of the first workpiece 31.

[0115] The heat Q transferred by the laser beam 60 to the second workpiece 32 and / or the first workpiece 31 leads to the formation of softened material or a material melt 70 in the respective area around the recess 50.

[0116] The invention is not limited to the fact that, as in Fig. Figure 1 shows a heating area 71 arranged next to the softened material or the molten material 70, but especially in the case of only softening of the material the heating area 71 can also include the softened material 70.

[0117] In the lower right part of the Fig. Figure 1 further shows a part of a connecting element 1 with a pin-like section 20 arranged in the recess 50. This represents the final state of a method according to the invention, in which, after completion of the laser drilling process, the pin-like section 20 was inserted into the recess 50, in particular controlled by a signal 66 for a Fig. 1 Device (not shown) for introducing fasteners into a workpiece. In the illustrated embodiment, the pin-like section 20 is coated with a solder material 26. The pin-like section 20 is firmly connected to the first workpiece 31 and / or the second workpiece 32 by means of a solder joint via both its outer surface 23 and its end surface 24.

[0118] The solder material 26 is softened or melted during and / or after the insertion of the pin-like section 20 into the recess 50 by transferring heat Q from the softened material or the molten material 70 produced by means of a laser beam 60, so that after the insertion of the pin-like section 20 the softened material or the molten material 70 is connected with the molten solder material 26, and so that after the cooling of the softened material or the molten material 70 a solid solder joint is formed between the pin-like section 20 and at least the first workpiece 31.

[0119] Alternatively to this embodiment, if molten material is present, a welded connection can also be formed between a material melt 70 and the pin-like section 20 if the pin-like section 20 is melted by the input of heat.

[0120] To describe one embodiment of the method according to the invention, reference is made below to the following: Fig. 2. Referenced.

[0121] This shows a partial step of a method according to the invention, in which a recess 50 of depth T is created in a first workpiece 31 and a second workpiece 32 arranged layer by layer above the first workpiece 31 by means of a laser beam 60. In this process, softened material or a material melt 70 and a heated area 71 are created by means of the heat transferred by the laser beam 60.

[0122] The laser beam 60 travels in a longitudinal direction 61. A portion of the laser beam 60 (not shown here) is reflected by a semi-transparent mirror 95, and another portion of the laser beam 60, traveling between the mirror 95 and the recess 50, passes through the mirror 95 and is focused by a converging lens 62. Reflection of the laser beam 60 at the bottom of the recess 50, in this illustration at the softened material or molten material 70, produces a reflected laser beam 67. The reflected laser beam 67 is partially reflected by the mirror 95 and reaches a [missing information - likely a specific location or component] in the Fig. 2 measuring devices not shown.

[0123] This measuring device can, for example, be an interferometer for performing optical coherence tomography (OCT). Using such a measuring method, the depth T of the recess 50 can be measured by determining the path length of the reflected laser beam 67. Upon reaching a defined depth T, a signal can be transmitted to a control unit 94. The control unit 94 can then, in response to the signal, switch off the laser source emitting the laser beam 60 or change the power of the laser beam 60, so that, for example, no further increase in the depth of the recess 50 occurs, but only heat is transferred, and so that, if necessary, as in Fig. Figure 1 shows an increase in the diameter of the created recess 50. When using an OCT measuring system, the reflected laser beam 67 can also be spectrally analyzed in order to analyze the material composition of the reflecting material at the bottom of the recess 50 based on characteristic absorption bands.

[0124] In the following, reference is made to embodiments of a welded or soldered joint according to the invention between a connecting element 1 and a workpiece 30. Fig. 3, Fig. 4a, Fig. 4b, Fig. 4c and Fig. 5. Referenced.

[0125] These each show a welded or soldered joint between a first workpiece 31 and a connecting element 1 shaped as a U-shaped clamp 10. The first workpiece 31 is positioned adjacent to a second workpiece 32.

[0126] The U-shaped clamp 10 has a first pin-shaped section 21 positioned in a first recess 51 and a second pin-shaped section 22 positioned in a second recess 52.

[0127] Details of the connection between the pin-like sections 21, 22 and the respective recesses 51, 52 are shown below as an example for the one in Fig. The first pen-like section 21 shown in Figure 3 is described, but applies to both the first pen-like section 21 and the second pen-like section 22 in the Fig. 3-5.

[0128] The first pin-like section 21 has a lateral surface 23 and an end surface 24. When the first pin-like section 21 is connected to the first workpiece 31, the first pin-like section 21 comes into contact with softened material or a molten material 70 of the first workpiece 31 by means of a portion of its lateral surface 23 and its entire end surface 24, whereby heat is transferred from the softened material or the molten material 70 to the first pin-like section 21. This leads to a heating of the first pin-like section 21, so that, depending on the material of the first pin-like section 21 and the heat input, a welded or brazed connection is formed between the first pin-like section 21 and the first workpiece 31.

[0129] By inserting the pin-like sections 21, 22 into the corresponding recesses 51, 52, at least a portion of the softened material or molten material 70 is displaced from the recesses 51, 52, leaving only a relatively thin layer of softened material or molten material 70 between the workpiece 31, 32 and the respective pin-like section 21, 22. This process removes impurities from the softened material or molten material 70, such as intermetallic phases. In the case of molten material 70, this process primarily cleans the melt pool. Consequently, a welded or brazed joint of sufficient strength can be achieved.

[0130] The first pin-like section 21 of the U-shaped clamp 10 is connected to the second pin-like section 22 via a corresponding pressure section 25, wherein the pressure section 25 is arranged essentially at right angles or acute angles to the pin-like sections 21, 22.

[0131] In the embodiments shown, the pin-like sections 21, 22 each have a tip 27 on their respective end faces 24, which facilitates the insertion of the respective pin-like section 21, 22 into the corresponding recess 51, 52 by means of self-centering.

[0132] The Fig. Figure 3 shows a sectional view of a U-shaped clamp 10, a first workpiece 31 and a second workpiece 32, wherein a layer of an adhesive 34 is arranged between the first workpiece 31 and the second workpiece 32 for pre-fixing the workpieces 31, 32.

[0133] In the Fig. In the embodiment shown in Figure 3, both the outer surface 23 and the end surface 24 of the U-shaped clamp 10 are coated with a solder material 26. When the first pin-like section 21 is connected to the first workpiece 31, heat is transferred from the softened material or the molten material 70 to the solder material 26, causing the solder material 26 to melt. This forms a soldered joint between the first pin-like section 21 and the first workpiece 31.

[0134] In the Fig. In the embodiment shown in Figure 3, the pressure section 25 is designed as a bending spring, wherein the pressure section 25, in its original form 13 shown with dashed lines, has a greater curvature than in the position of the finished welded or brazed joint. During the insertion of the pin-like sections 21, 22 into the corresponding recesses 51, 52, an insertion force 11 is exerted on the U-shaped clamp 10, which pushes the clamp into the recesses 51, 52 until the pressure section 25 comes into contact with a surface 33 of the second workpiece 32 and beyond. This results in a deformation of the pressure section 25 from its original form 13 into the form shown here as pressure section 25.

[0135] As a result, after deformation, a spring force 12 from the pressure section 25 acts on the surface 33 of the second workpiece 32. Consequently, the second workpiece 32 is pressed against the first workpiece 31 connected to the U-shaped clamp 10, thereby creating a frictional connection between the first workpiece 31 and the second workpiece 32.

[0136] The Fig. Figure 4a shows a sectional view of an end-weld joint between a workpiece 30 and another workpiece (not shown), where the section plane represents a separation plane 40 between the workpieces. In the Fig. 4b and Fig. Figure 4c shows a perspective view of an end-weld joint between a first workpiece 31 and a second workpiece 32, with the end-weld joint in the Fig. 4b is shown partially cut away in the separation plane 40.

[0137] The end-seam connections can be welded or soldered connections and are each realized by U-shaped clamps 10 with pin-like sections 21,22, wherein the respective pressure section 25 is positioned parallel to the corresponding separation plane 40 between the first workpiece 31 and the second workpiece 32.

[0138] The first and second recesses 51, 52 are each formed by grooves on the respective surfaces of the first workpiece 31 and the second workpiece 32, such that, when the workpieces 31, 32 are positioned relative to each other, the first and second recesses 51, 52 form a common recess 53 located in the parting plane 40. The pin-like section 21, 22 is inserted into the common recess 53 during the welding or brazing process. Thus, in the finished weld or brazing joint, the pin-like section 21, 22 is connected to the two workpieces 31, 32 on opposite sides of its outer surface 23.

[0139] The Fig. 5 shows a perspective view of an analogous representation to the representation in Fig. 3 formed welded or soldered joints, wherein the pressure section 25 is not formed as a bending spring, but runs perpendicular to the pin-like sections 21, 22. The pin-like sections 21, 22 are arranged perpendicular to the parting line 40 between the first workpiece 31 and the second workpiece 32. The recesses 51, 52 each consist of a blind hole in the first workpiece 31 and a through hole in the second workpiece 32, with the respective pin-like section 21, 22 passing through the respective through hole and being inserted into the respective blind hole, where it is connected to the material of the first workpiece 31 by means of a welded or soldered joint. However, it should not be excluded that the pin-like section 21, 22 also forms a welded or soldered joint with the second workpiece 32.

[0140] In the Fig. Figure 6 schematically illustrates partial steps of a method according to the invention for attaching a fastener to a workpiece.

[0141] Two workpieces 31, 32 arranged in layers above each other are shown, in which a first recess 51 and a second recess 52 for the insertion of a connecting element 1, in particular in the form of a U-shaped clamp 10, are simultaneously produced side by side by means of a first laser beam 68 and a second laser beam 69.

[0142] Furthermore, a device 93 for inserting fasteners with a holding tool 80 is shown. A U-shaped clamp 10 held by the holding tool 80 is also shown. The holding tool 80 is mechanically connected to a translational guide 81, so that the U-shaped clamp 10 can be inserted into the recesses 51, 52 by moving the holding tool 80 within the translational guide 81 with its pin-like sections.

[0143] The distance between the recesses 51,52 corresponds to the distance between the pin-like sections and the diameter of the recesses 51,52 corresponds at least to the diameter of the pin-like sections.

[0144] Detail view 6a shows a first alternative arrangement for the simultaneous generation of the first laser beam 68 and the second laser beam 69. This shows a first laser source 91 for generating the first laser beam 68 and a second laser source 92 for generating the second laser beam 69. These are focused by means of a first converging lens 63 and a second converging lens 64.

[0145] The Fig. Figure 7 shows a second alternative arrangement for the simultaneous generation of a first laser beam 68 and a second laser beam 69. In this arrangement, a single laser beam is generated by a first laser source 91. The laser beam passes through a first converging lens 63 and a beam splitter 65, which splits the laser beam into the first laser beam 68 and the second laser beam 69. The first laser beam 68 and the second laser beam 69 are then focused by a second converging lens 64 and strike a workpiece 30, in which a first recess 51 and a second recess 52 are created by means of the laser beams 68 and 69.

[0146] The Fig. Figure 8a shows a device for producing U-shaped clips 10 from a wire 140, wherein the device comprises a cutting and bending device 100, a reel 120 and a wire feeder 130, in particular a two-roller feeder. By means of the wire feeder 130, the wire 140 is unwound from the reel 120 and fed to the cutting and bending device 100.

[0147] The cutting and bending device 100 comprises a punch 101 with a bending segment 102 having a U-shaped recess in cross-section and a cutting segment 103. The cutting and bending device 100 also includes a die 104, which has a projection shaped complementary to the bending segment 102. The punch 101 is mechanically connected to a cylinder 110, so that when the cylinder 110 is moved, the punch 101 can be moved towards the die 104.

[0148] During a movement of the punch 101, a wire section 141 is cut from a wire 140 located in the cutting and bending device 100 by means of the cutting segment 103 and a counter blade 105, and in the same stroke the wire section 141 is bent into a U-shape, forming a U-shaped clamp 10. The produced U-shaped clamp 10 can be ejected from the cutting and bending device 100 by means of an optional ejector and, in particular, fed to a device 93 for inserting fasteners.

[0149] The Fig. Figure 8b shows a U-shaped clamp 10 produced by means of the cutting and bending device 100 with a straight pressure section 25 and the Fig. Figure 8c shows a U-shaped clamp 10 with a bent pressure section 25 produced by means of a cutting and bending device 100 according to the invention. The clamp can be formed by cutting and bending the U-shaped clamp 100 with a bent pressure section 25. Fig.The bending of the bent pressure section 25 shown in Figure 8c is produced during the described bending process by means of a correspondingly shaped punch 101. Reference symbol list 1 Connecting agent 10 U-shaped clamps 11 Contribution power 12 spring force 13 Original form 20 Pen-shaped section 21 First pen-like section 22 Second pen-like section 23 Surface area 24 Front surface 25 Contact section 26 Solder material 27 top 30 workpieces 31 First workpiece 32 Second workpiece 33 Surface 34 Adhesive 40 Separation level 50 recess 51 First recess 52 Second recess 53 Common recess T depth 60 laser beam 61 Laser beam longitudinal direction 62 Converging lens 63 First converging lens 64 Second converging lens 65 beam splitters 66 Signal 67 Reflected laser beam 68 First laser beam 69 Second laser beam P Performance t time Q Heat 70 Softened material or molten material 71 Heating area 80 Holding tools 81 Translation guidance 91 First laser source 92 Second laser source 93 Device for inserting fasteners 94 Control unit 95 mirrors 100 cutting and bending device 101 stamps 102 Bending segment 103 cutting segment 104 die 105 Counter blade 110 cylinders 120 reel 130 wire conveyors 140 wire 141 Wire section

Claims

[1] Method for mechanically fastening a fastener (1) to a workpiece (30), wherein the procedure comprises the following steps: - Creating a recess (50), in particular a blind hole or a through hole, in a workpiece (30) using a laser beam (60), - Heating the workpiece (30) at least in the area of ​​the recess (50) by means of the laser beam (60), so that softened material or a material melt (70) is formed in the recess (50), - Inserting a pin-like section (20) of a connecting element (1), in particular a U-shaped clamp (10), into the recess (50), - Formation of a welded or soldered joint between the pin-like section (20) of the fastener (1) and the workpiece (30) in the recess (50), wherein at least intermittently, the heating of the workpiece (30) is carried out simultaneously with the creation of the recess (50) in order to form the softened material or the material melt (70). [2] Method for mechanically fastening a connecting element (1) to a workpiece (30) according to claim 1, characterized by , that by inserting the pin-like section (20) into the recess (50) at least a part of the molten material or the softened material (70) is displaced from the recess (50). [3] Method for mechanically fastening a connecting element (1) to a workpiece (30) according to claim 1 or 2, characterized by , that during the insertion of the pin-like section (20) into the recess (50) the connecting element (1) or a holding tool (80) holding the connecting element (1) interrupts the laser beam (60). [4] Method for mechanically fastening a connecting element (1) to a workpiece (30) according to one of the preceding claims, characterized by , that the fastener (1) has a contact section (25) which extends at an angle of 45° to 135° to the pin-like section (20) of the fastener (1), wherein the fastener (1) is connected to the workpiece (30) such that the contact section (25) bears against a surface (33) of a workpiece under a compressive preload. [5] Method for mechanically fastening a connecting element (1) to a workpiece (30) according to one of the preceding claims, characterized by, that a first workpiece (31) and a second workpiece (32) are positioned adjacent to each other or at a small distance from each other on a parting plane (40), wherein the first workpiece (31) has a first recess (51) into which the pin-like section (20) is to be inserted, and wherein the second workpiece (32) has a second recess (52) and: i) the pin-like section (20) is inserted at an angle of 30° to 150°, in particular 90°, to the parting plane (40) through the second recess (52) of the second workpiece (32) into the first recess (51) of the first workpiece (31), or ii) the first recess (51) and the second recess (52) are each formed as a channel on the respective surface of the first workpiece (31) and the second workpiece (32), wherein the first recess (51) and the second recess (52) are arranged in the relative position of the workpieces (31, 32) such that the first recess (51) and the second recess (52) together form a common recess (53), in particular a blind hole or through hole, arranged in the parting plane (40), wherein the pin-like section (20) is inserted into the common recess (53), such that the pin-like section (20) is welded or brazed to the two workpieces (31, 32) on opposite sides of its lateral surface (23), or iii) wherein the first recess (51) and the second recess (52) are each designed as a blind hole or through hole, and wherein the connecting element (1) has a first pin-like section (21) and a second pin-like section (22), wherein the first pin-like section (21) is inserted into the first recess (51) and wherein the second pin-like section (22) is inserted into the second recess (52). [6] Method for mechanically fastening a connecting element (1) to a workpiece (30) according to one of the preceding claims, characterized by , that the welded or soldered joint is only made between a lateral surface (23) of the pin-shaped section (20) and the workpiece (30). [7] Method for mechanically fastening a connecting element (1) to a workpiece (30) according to one of the preceding claims, characterized by, that when the recess (50) is created using the laser beam (50), the power (P) of the laser beam (60) is adjusted in a burn-in phase such that the depth of the recess (50) increases in the longitudinal direction (61) of the laser beam, and when the recess (50) is created, upon reaching a defined value of a physical parameter, in particular the depth (T) of the recess (50), the power (P) of the laser beam (60) is adjusted in a heating phase such that a lower depth increase per unit of time occurs compared to the burn-in phase, wherein during the heating phase the material surrounding the recess (50) is heated using the laser beam (60). [8] Connection system for mechanically fastening a connecting element (1) to a workpiece (30), having - a laser source (91) for generating a laser beam (60), wherein the laser beam (60) is configured to create a recess (50), in particular a blind hole or through hole, in a workpiece (30) and to heat the workpiece (30) at least in the area of ​​the recess (50) in such a way that softened material or a material melt (70) can be formed in the recess (50), - a device for inserting fasteners (93) which is configured to insert a pin-like section (20) of a fastener (1), in particular a pin-like section (20) of a U-shaped clamp (10), into the recess (50) produced by means of the laser beam (60) in such a way that a welded or soldered joint can be made between the pin-like section (20) and the workpiece (30) in the recess (50), characterized by the fact that the connection system has a control device (94) which is configured to adjust the power (P) of the laser beam (60) during the creation of the recess (50) using the laser beam (60) in a burn-in phase such that the depth of the recess (50) increases in the longitudinal direction (61) of the laser beam, and when a defined value of a physical parameter, in particular the depth (T) of the recess (50), to adjust the power (P) of the laser beam (60) in a heating phase such that a smaller increase in depth per unit of time occurs compared to the burn-in phase, while simultaneously heating the material surrounding the recess (50) using the laser beam (60). [9] Connection system for mechanically fastening a connecting element (1) to a workpiece (30) according to claim 8, characterized by, that the connection system comprises a bending and cutting device (100) for producing a connecting element (1) with a pin-like section (20), in particular a U-shaped clamp (10), wherein the bending and cutting device (100) comprises a punch (101) and a die (104), and wherein the punch (101) comprises a bending segment (102) and a cutting segment (103), wherein the bending and cutting device (100) is configured to cut a wire section (141) from a wire (140) by means of the cutting segment (103) by moving the punch (101) relative to the die (104) and to deform the wire section (141) by means of the bending segment (102) in the same step. [10] Motor vehicle, in particular passenger car, comprising at least one workpiece (30) and a connecting means (1), wherein the connecting means (1) is mechanically attached to the workpiece (30) by means of a welded or soldered joint produced by a method according to one of claims 1 to 7.

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