ULTRASONIC WELDING DEVICE AND METHOD FOR ULTRASONIC WELDING

Description

[0001] The subject matter relates to an ultrasonic welding device and a method for ultrasonic welding.

[0002] Today, a multitude of different welding processes exist, differing essentially only in the method of heat generation. Ultrasonic welding has established itself as a proven method for firmly and securely joining cables, terminals, and connecting elements, particularly in motor vehicles.

[0003] In ultrasonic welding, the electrical vibrations generated by an ultrasonic generator are converted into mechanical vibrations by an excitation unit and transmitted to a welding tool, the sonotrode. The sonotrode transmits the mechanical vibrations to the parts to be welded, the weld metal, which are arranged between the sonotrode and a counterpart, the anvil. The transmission of the ultrasonic vibrations to the weld metal creates heat-inducing intermolecular friction. A force directed perpendicularly from the sonotrode onto the weld metal fixes the parts to be welded between the sonotrode and the anvil at the weld point, creating a permanently strong and homogeneous weld.

[0004] Ultrasonic welding technology is characterized, among other things, by the short welding time and the formation of strong and permanent connections between the welded parts.

[0005] A problem with ultrasonic welding, however, arises when moving parts are located near the weld. While the parts to be welded between the sonotrode and the anvil are held in place by the perpendicular force of the sonotrode, other moving parts located near the weld are subjected to unwanted movement by the mechanical vibrations during the welding process. The induced movements can be translational, rotational, or oscillatory, all of which reduce the quality of the weld and can lead to surface damage and even cracking.

[0006] Simply holding down the moving parts will not solve the problem, as this will cause unwanted marks and scratches on the moving parts as well as on the flat part and the support surface.

[0007] Coated workpieces, such as tinned surfaces often used for corrosion protection, are particularly susceptible to surface damage in this respect.

[0008] Publication EP 0 913 246 A1 relates to a method for melt-bonding a hard resin product to a substrate made of a silicon-containing material, an apparatus for carrying out this method, a method for producing a window glass in which a hard resin product is melt-bonded to a glass substrate, and a window glass produced according to this method.

[0009] The publication US 2006 / 105589 A1 relates to window panes for vehicles and a method for connecting an electrical connector to an electrical conductor attached to the window pane.

[0010] The publication US 2012 / 107546 A1 relates to methods for holding and enclosing a layer of vibration-damping material against a selected surface area of ​​a vibratory metal object in order to reduce mechanical vibrations generated or transmitted by the object by causing Coulomb damping and / or viscous damping of at least the adjacent part of the object

[0011] The publication DE 10 2012 006641 A1 relates to a cable connection element and a method for producing such a cable connection element.

[0012] The publication DE 198 33 590 C relates to a method for welding an extended optical component to a metal fastening, use and an optical assembly.

[0013] Based on this prior art, the application was based on the objective of providing a device and method for ultrasonic welding that minimizes the movements induced by welding while minimizing material damage. Furthermore, the device should be as easy to retrofit to existing systems as possible.

[0014] This object is achieved according to claim 1 and claim 3.

[0015] In an ultrasonic welding device, the workpiece to be welded can be arranged between the sonotrode and the anvil. In this case, a flat part is welded to a joining part or to a connecting part, such as a cable core, in particular the strands of a cable, using ultrasonic welding (USS).

[0016] During USS, vibrations are introduced into the flat part. These vibrations can propagate throughout the flat part and be transmitted to components arranged on the flat part, especially fastening parts. These parts, which are not firmly attached to the flat part, also begin to vibrate, and the resulting vibrations can cause damage to the parts' surfaces.

[0017] In this case, a fastening element can be arranged on a flat part and, in particular, held in a form-fitting manner between the flat part and a joining part. However, the fastening element can also be arranged captively on the flat part without the joining part, e.g., by suitable pressing or the like. A damping element resting against the fastening element during ultrasonic welding can be arranged in such a way that relative movement between the fastening element and the flat part and / or the joining part is restricted, preferably prevented, during ultrasonic welding.

[0018] Specifically, the fastening element is pressed against the flat part with the aid of at least one damping element arranged on the USS device. The contact pressure, on the one hand, supports the fastening element against the flat part, so that vibrations caused by the USS in the fastening element are reduced, or preferably prevented. In addition, the contact pressure presses the fastening element against the flat part in such a way that the flat part is elastically deformed by the contact pressure. The elongation in the direction of the contact force is preferably between 0.5 and 1%. This elongation dampens the flat part, so that the vibration imposed by the USS is dampened in the flat part itself.

[0019] The design of the sonotrode is also relevant for the quality of ultrasonic welding processes. It can be made from a variety of materials. Sonotrodes made of aluminum, titanium, or steel are preferred, although other suitable materials can also be used. The shapes of the sonotrodes can also vary considerably; for example, they can be rectangular, rounded, conical, or cylindrical. The working surface of the sonotrode is preferably shaped as uniformly as possible, as this is the only surface that comes into direct contact with the welded part, and marks on components should be avoided. The mechanical vibration transmitted by the sonotrode to weld the welded parts can run either perpendicular to or parallel to the parts to be welded.

[0020] A restriction of the movement of the fastening element and the flat part and / or the joining part can mean that the fastening element can only perform slight translational, rotational, and vibratory movements relative to the flat part and / or the joining part. Such translational movements can preferably mean a movement of at least less than 5 mm along the contact surfaces between the fastening element and the flat part and / or the joining part, preferably less than 1 mm, particularly preferably less than 0.2 mm. Such rotational movements can preferably mean a rotation of less than 5° around the axis perpendicular to the contact surface between the fastening element and the flat part and / or the joining part, preferably less than 1°, particularly preferably less than 0.2°.Such vibration movements may mean a deflection perpendicular to the contact surface between the fastening element and the flat part and / or the joining part of less than 5 mm, preferably less than 1 mm, particularly preferably less than 0.2 mm.

[0021] By limiting the movement of the fastening element relative to the flat part and / or the joining part, damage to the surface of the flat part is prevented. The quality of the welded joint can be optimized. Particularly in the case of cables, clamps, or connecting elements used in motor vehicles, welded joints are subject to stringent requirements in terms of stability and durability. Welded joints in motor vehicles should, if possible, function over the entire service life of the vehicle. By dampening the flat part through elastic deformation caused by the contact pressure of the damping element, the flat part itself is dampened, and a welding process is optimized at a weld point in the area of ​​the flat part.

[0022] A positive-locking retention of the fastener between the flat part and the joining part is particularly advantageous when forming a material-to-material connection between the joining part and the flat part, where the joining part has the task of holding the fastener in position. This prevents the fastener from slipping, for example, while the joining part is being joined to the flat part using ultrasonic welding. It can also prevent the fastener from vibrating relative to the flat part when welding the flat part to a cable using ultrasonic welding.

[0023] According to one embodiment, it is proposed that the fastening element be held freely on the flat part. Free-running holding in this sense can mean that the fastening element is held in place but can still rotate about its longitudinal axis. This makes it possible, for example, in the case of a nut as a fastening element, for it to be screwed to a bolt despite the free-running holding, by rotating the nut about its longitudinal axis.

[0024] The free-running holding can be achieved by the fastening element radially engaging behind a fold in a hole in the flat part on one side and on the other side resting with a head or flange on the surface of the flat part in the area of ​​the circumference of the hole.

[0025] The joining part can also partially or completely surround the fastening element. The joining part can be designed as a type of fastening ring that at least partially surrounds the fastening element. The fastening ring can, for example, be designed so that it only partially surrounds the fastening element, but it can also completely surround the fastening element. The joining part can also be a type of fastening nut that completely encloses the fastening element instead of just surrounding it. The joining part is preferably made of metal, but can also be made of a non-metallic material, such as a plastic.

[0026] According to one embodiment, it is proposed to hold the fastening element freely by two joining parts. Holding it with the help of two joining parts ensures greater flexibility with regard to the arrangement of the joining parts. For example, a fastening element can also be held by two angularly shaped joining parts fixed to the flat part. The fixing of the angularly shaped joining parts could be particularly simple when using Z-shaped joining parts, in that the surface of the Z-shaped joining part resting on the flat part is materially bonded to the flat part using an ultrasonic welding process. However, the desired free movement of the fastening element may require a part-circular design of the upper collar of the Z-holding angle-shaped joining part. In addition to an arrangement of two joining parts, an arrangement of three or more joining parts for holding the fastening element is also conceivable.

[0027] Furthermore, an arrangement in which one or more joining parts can be fixed to the flat part in a material-to-material, form-fitting, and / or force-fitting manner, rather than by ultrasonic welding, would also be conceivable. For example, one or more joining parts can hold a fastening element in a form-fitting manner by being glued, screwed, riveted, or soldered to the flat part.

[0028] It is also proposed that the flat part be welded at a first end to a connecting part, e.g., to a cable or cable core, or strands of a cable, using a USS (uniform welding). At the same time, the fastening element is pressed against the flat part using the USS device. For this purpose, a holding arm is provided on the USS, on which the damping element is arranged. The holding arm presses the damping element axially toward the fastening element.

[0029] One of the contact surfaces between the sonotrode and the at least one joining part or a connecting part to be welded to the flat part is arranged spatially away from the fastening element. Thus, the fastening element can be arranged on the flat part away from the sonotrode. Vibrations caused by the sonotrode are transmitted through the flat part. With the help of the damping element in question, it is possible to dampen these vibrations as much as possible, so that the fastening element vibrates as little as possible relative to the flat part.

[0030] At least two side slides, which can preferably be moved linearly relative to one another, are arranged on the USS device. The flat part can be fixed in place by means of the side slides by clamping it between the side slides. The flat part preferably protrudes on both sides of the side slides. On one side, the flat part can be welded to a cable using USS. On the other side of the side slide, the flat part with the fastening element can protrude. When inserted into the USS, the fastening element can be guided by means of a guide that engages with the fastening element, so that the flat part is aligned with the fastening element on the side slides. Once clamped, the flat part is held between the side slides to the USS.

[0031] A holding arm can be arranged on one of the side shifters. While the side shifters are moved linearly towards the flat part, the holding arm can be moved at an angle to it, in particular perpendicular to it, towards the surface of the flat part. This allows a damping element arranged on the holding arm to be moved towards the fastening element. With the help of a suitable contact pressure, the damping element can be pressed against the fastening element. This essentially suppresses the vibration of the fastening element. At the same time, with a suitable contact pressure, the flat part can be elastically deformed. Through this deformation, the vibration can also be dampened in the flat part itself by the USS. A second damping element can be provided on the side of the fastening element axially opposite the first damping element.This preferably rests only on the flat part, not directly on the fastening element. The fastening element, together with the flat part, is then pressed between the two damping elements. This results in optimal damping and, at the same time, mechanical protection of the flat part on the side of the second damping element.

[0032] The at least one damping element is arranged on a side of the support arm facing the fastening element. Thus, the first damping element can be pressed against the fastening element.

[0033] A second damping element can be arranged on a surface of the anvil facing the flat part. The anvil can be understood as the support surface of the flat part on the USS. The anvil is not just the part of the USS device opposite the sonotrode, but is understood here in a broader sense. The anvil is arranged on the side on which the flat part rests on the USS device, or on the side of the flat part facing away from the fastening element. The second damping element is provided on this side. It is clamped between the flat part and the anvil. Preferably, the second damping element is clamped between the guide for the fastening element and the anvil. The guide for the fastening element can also be understood as a holding unit.

[0034] Preferably, the first damping element in the USS rests directly against or on the fastening element. The second damping element is preferably arranged on the flat part. In particular, the second damping element is spaced apart from the fastening element. Thus, in the USS, there is no contact between the second damping element and the fastening element.

[0035] Because the holding arm is movable toward the fastening element, the damping element can be pressed against the fastening element with a stroke of at least 0.1 mm, preferably between 0.5 mm and 5 mm, in particular approximately 1 mm, 2 mm, 3 mm, 4 mm, or 5 mm, elastically deforming it. Depending on the elasticity of the damping element, the stroke can be adjusted so that the fastening element is pressed against the flat part with sufficient force.

[0036] The retaining arm presses the first damping element against the fastening element, preferably with a contact pressure of at least 0.1 bar, preferably at least 1 bar, in particular between 1 bar and 6 bar, preferably between 3 bar and 6 bar. Depending on the contact pressure, different elastic deformations of the flat part result, and the damping of the USS vibration can be varied.

[0037] The damping element can be positioned particularly easily on the holding arm if the first damping element is arranged with a transition fit or a press fit on the holding arm, in particular in a blind hole in the holding arm.

[0038] As already mentioned, vibrations can be dampened by the USS in the flat part if the holding arm presses the damping element against the fastening element in such a way that the flat part is elastically deformed.

[0039] At least one of the damping elements can be made of an elastic material, in particular an elastomer, in particular a polyurethane. The material preferably has a hardness between 40 and 120 Shore, in particular between 60 and 100 Shore, preferably approximately 80 Shore, preferably according to DIN EN ISO 868 and / or DIN ISO 7619-1. The damping element preferably has a shear modulus of 10-500 MPa at room temperature. This achieves particularly good damping properties for vibrations in the ultrasonic range.

[0040] According to one embodiment, the sonotrode is arranged laterally of the fastening element. In particular, at least one of the contact surfaces of the sonotrode and the at least one joining part or the cable is arranged laterally of the fastening element. In an embodiment in which at least one joining part holds the fastening element in a form-fitting manner, while the joining part is integrally connected to the flat part using an ultrasonic welding process, it is advantageous if the fastening element is arranged laterally of the sonotrode. This provides sufficient space for the formation of a welded connection between the flat part and the joining part. If the formation of two welded connections for fixing the joining part to the flat part is desired, repositioning the sonotrode or the workpiece for the formation of the second welded connection would be conceivable.Alternatively, the use of a specially U-shaped sonotrode would also be conceivable, allowing two weld joints to be formed simultaneously between at least one joining part and the flat part. In this case, the fastening element would preferably be located between the two contact points of the sonotrode and the joining part when forming the integral connection between the flat part and at least one joining part.

[0041] The fastening element can be a rotary fastening element, in particular a screw, a nut, a plug-and-twist fastener, or a bayonet lock. The fastening element can serve to connect a fastener; for example, a nut can serve as a fastening element for connecting a screw, and vice versa. This allows different connecting elements to be connected to one another in a particularly simple manner. The fastening element can be made of metal, preferably copper or one of its alloys. In particular, the rotary fastening element is a forged or cold-formed part.

[0042] According to one embodiment, the fastening element has a radially outward-facing collar. The collar can be partially or completely circumferential. A collar that points radially outward on the fastening element simplifies the structure and shape of the joining elements used and enables a simultaneously positive-locking and free-running holding of the fastening element between the joining part and the flat part.

[0043] According to one embodiment, the fastening element has an axially extending collar arranged in a bore in the flat part. This collar is bent outward at its axial end so that it is arranged in a fold in the region of the circumference of the bore, in particular a circumferential fold. As a result, the fastening element is held captively to the flat part, but remains rotatable in the bore when the collar is bent into the fold with a clearance fit.

[0044] According to an advantageous embodiment, the flat part is designed as a cable connection element. The cable connection element can preferably be a cable lug, in particular a friction-welded cable lug, crimped cable lug, or ultrasonic-welded cable lug. Cable connection elements, in particular cable lugs, are suitable for a simple and secure connection of cables, particularly in motor vehicles. Preferably, a cable, in particular the strands or the core of the cable, can be fastened to the flat part by means of USS. In the region of the flat part, the cable lug is preferably metallic, made of copper or a copper alloy, as well as aluminum or an aluminum alloy. In special embodiments, however, it is also possible for the flat part to be formed from a non-metallic material. On the flat part of the cable lug there is a fastening element that is held in a form-fitting manner between the flat part and at least one joining part.The fastening element can be made of copper or a copper alloy, as well as aluminum or an aluminum alloy. The fastening element can be coated, for example, in particular nickel-plated and / or tin-plated. The fastening element can be a rotary fastening element, in particular a screw, a nut, a plug-and-twist fastener, or a bayonet lock. The fastening element can be used to connect a fastening device.

[0045] According to one embodiment, it is proposed that a holding unit holds the flat part in a form-fitting manner between the sonotrode and the anvil. In this case, the holding unit preferably surrounds the flat part on three sides and has a structure complementary to the flat part. The holding unit is preferably a component made of metal, preferably forged or cold-formed. In an embodiment in which the holding unit holds a U-shaped cable lug in a form-fitting manner between the sonotrode and the anvil on three sides, the holding unit preferably has a U-shaped recess as a complementary structure. A cable lug, for example, can be inserted into this recess and held in a form-fitting manner. This is particularly advantageous when work is carried out on the cable lug, such as the material-to-material joining of parts by means of ultrasonic welding.The mounting unit provides particularly stable support when the U-shaped recess runs essentially, preferably exactly, along the component's main axis of inertia. The mounting unit is preferably designed as a guide. The flat part, together with the fastening element, can be aligned to the USS device in front of the USS using the mounting unit. The flat part is then fixed to the USS device in the aligned state using a second side slider.

[0046] The mounting unit can be arranged on the anvil in a form-fitting manner, preferably fixed to the anvil. Fixing to stabilize the mounting unit on the anvil can be achieved, for example, via at least one hole in the mounting unit. Fixing can then be achieved via screws, threaded rods, bolts, or dowels. Corresponding threads or holes can then be located in the anvil. Fixing is preferably achieved via at least two holes, which can be arranged symmetrically to the U-shaped recess.

[0047] In order to limit the movement of the fastening element relative to the flat part and / or the joining part, it is proposed to arrange a damping element on, preferably on, the fastening element. Arranging the damping element directly on the fastening element here means being arranged directly on a surface facing the fastening element. In this way, the greatest possible restriction of the movement of the fastening element relative to the flat part and / or the joining part can be achieved. Preferably, the damping element also has a shape that is as similar as possible to the surface of the fastening element adjacent to the damping element. For example, for a nut as a fastening element, a cylindrical shape with an outer diameter similar to the outer diameter of the nut head would be ideal.

[0048] According to an advantageous embodiment, it is proposed that a second damping element be arranged on a surface of the anvil facing the flat part, preferably between the anvil and the flat part, in particular on a side of the flat part facing away from the first damping element. If no damping element were present between the flat part and the anvil, the surface of the flat part in the area of ​​contact with the anvil could be damaged during ultrasonic welding.

[0049] According to one embodiment, at least one of the damping elements can be made of an elastic material, in particular polyurethane. In addition to polyurethane, other elastic materials with good damping properties, such as rubber or plastic foams, could also be used.

[0050] In an advantageous embodiment, a holding arm can be arranged on the ultrasonic welding device. The holding arm can preferably be arranged such that a force exerted by the holding arm limits relative movement between the fastening element and the flat part and / or joining part during ultrasonic welding. Advantageously, the force is applied as perpendicular as possible to the surface of the damping element. In this case, a force aligned as perpendicular as possible to the surface of the damping element reveals an efficient type of force transmission. Furthermore, the holding arm is preferably arranged next to the sonotrode. On the one hand, it is possible for the holding arm to be arranged as an attachment on a side shift separately next to the sonotrode and to limit relative movement between the fastening element and the flat part and / or joining part during ultrasonic welding by transmitting force to the damping element.

[0051] Another subject matter is a method for ultrasonic welding, in which a fastening element is captively arranged on a flat part, and a damping element is applied to the fastening element in such a way that relative movement between the fastening element and the flat part is restricted during subsequent ultrasonic welding. Preferably, the fastening element is restricted in its relative movement to the flat part and / or the joining part by a force exerted perpendicularly on the damping element by a holding arm.

[0052] The subject matter is explained in more detail below using drawings showing exemplary embodiments. The drawing shows: Fig. 1a shows an exploded view of a specific arrangement of a joining part, a fastening element and a flat part; Fig. 1b shows the specific arrangement of a joining part, a fastening element and a flat part according to Fig. 1y in the assembled state; Fig. 2a shows an exploded view of an alternative embodiment of the specific arrangement from Fig. 1a with the use of two joining parts; Fig. 2b the actual arrangement of the alternative embodiment according to Fig. 2a in the assembled state; Fig. 3a a sectional view of an alternative embodiment of the subject arrangement with a captured nut; Fig. 3b a sectional view of the subject arrangement of the alternative embodiment according to Fig. 3a in the assembled state; Fig. 4 Mounting unit in perspective view; Fig. 5 Upper damping element in perspective view; Fig. 6 Lower damping element in perspective view; Fig. 7 Sectional view of an arrangement of a form-fitting fastening element with a laterally arranged sonotrode using the example of a nut as a fastening element; Fig. 8 Sectional view of an arrangement of a form-fitting fastening element with a U-shaped sonotrode arranged on a holding arm using the example of a screw as a fastening element; Fig. 9 Sectional view of an arrangement of a form-fitting fastening element using the example of a bayonet lock as a fastening element with a U-shaped sonotrode arranged on a holding arm; Fig. 10 Perspective view of an arrangement of a form-fitting fastening element with a U-shaped sonotrode arranged on a holding arm; Fig.11Sectional view of an arrangement of a fastening element with a damping element arranged on a holding arm; Fig. 12Perspective view of an arrangement of a fastening element with a damping element arranged on a holding arm; .

[0053] Fig. 1a shows an actual arrangement of a joining part 10, a fastening element 8, and a flat part 2. The flat part 2 has a recess 6 arranged at one end and a through-opening 4. As an example of a fastening element 8, a nut is shown, which has a radially outward-facing collar 9. The joining part 10 has a connection surface 14 and a fastening ring 12 arranged next to the connection surface 14.

[0054] The fastening element 8 can be arranged in a form-fitting manner between the flat part 2 and the joining part 10. In this case, the fastening ring 12 of the joining part encloses the circumferential collar 9 of the fastening element 8. For a simultaneously form-fitting and rotatable holding of the fastening element 8 on the flat part, the fastening ring 12 of the joining part and the circumferential collar 9 of the fastening element 8 can have the same profile. The outer diameter of the circumferential collar 9 can also be larger than the inner diameter of the fastening ring 12, but smaller than its outer diameter. For the example of the form-fitting arrangement of a nut on a flat part 2, in particular a cable lug, this has the advantage that the nut can still rotate about its longitudinal axis despite its captive fastening and can therefore also be screwed with a fixed screw.

[0055] The terminally arranged trough 6 serves to accommodate the insulation of a cable with its insulation stripped at the end. The end of the stripped cable can then be welded to the flat part 2, for example, using an ultrasonic welding process. When welding cables to cable connection elements, it is preferable to ensure that the parts to be welded are made of the same materials or the same elements in order to prevent contact corrosion. The cable can, for example, be made of an aluminum material and the flat part of a copper material, although the flat part is covered with aluminum material in the area of ​​the connection point, e.g., by roll cladding. This material combination can of course also be exactly the opposite, i.e. the cable made of a copper material and the flat part of an aluminum material.

[0056] Fig. 1b shows the actual arrangement of a joining part 10, a fastening element 8 and a flat part 2 according to Fig. 1a in the assembled state, which shows the positive arrangement of the fastening element 8 between the flat part 2 and a joining part 10.

[0057] In this arrangement, the connection surface 14 of the joining part 10 can preferably be welded to the flat part 2 by means of an ultrasonic welding process, while the fastening element 8 is already held to the flat part 2 by the fastening ring 12 of the joining part 10.

[0058] Fig. 2a shows an exploded view of an alternative embodiment of the subject arrangement from Fig. 1a with the use of two joining parts 10 a and one flat part 2 a with extended end.

[0059] The alternative embodiment of the joining parts 10a consists of a connecting surface 14a and a fastening collar 12a arranged thereon. The flat part 2a has an extended end for supporting a second joining part 10a.

[0060] By holding the parts together using two joining parts 10 a, greater flexibility is ensured with regard to the arrangement of the joining parts 10 a. This means that other elements can also be fastened to the flat part 2 a directly next to the fastening element 8, since the joining part 10 a in this embodiment is not completely ring-shaped and thus still offers space for other elements. The size and shape of the connection surface 14 a is not limited to the embodiment shown in the figures. Alternatively, smaller or larger connection surfaces 14 a of the joining parts 10 a with other shapes can be used. The only important thing here is that the connection surface 14 a of the joining parts 10 a is not too small to be able to create a stable, material-locking connection with the flat part 2 a using the ultrasonic welding process.

[0061] The desired rotatability of the fastening element 8 requires a circular-shaped design of the fastening collars 12a of the joining parts 10a. In addition to an arrangement of two joining parts 10a, an arrangement of three or more joining parts 10a for holding a fastening element 8 is also conceivable.

[0062] Fig. 2b shows the alternative embodiment using two joining parts 10 a and a flat part with extended end 2 a according to Fig. 2a in the assembled state, which shows the positive arrangement of the fastening element 8 between the flat part 2 a and the joining parts 10 a.

[0063] In this arrangement, the connecting surfaces 14 a of the joining parts 10 a can preferably be welded to the flat part 2 a by means of an ultrasonic welding process, while the fastening element 8 is already held on the flat part 2 a by the fastening collars 12 a of the joining parts 10 a.

[0064] In this case, a sonotrode 28 can either be arranged laterally from the fastening element 8 and weld one joining part 10 a after the other to the flat part 2 a or, in the case of a U-shaped sonotrode 28, can also weld both joining parts 10 a to the flat part 2 a simultaneously, wherein the fastening element 8 is then preferably arranged between the U-shaped sonotrode 28.

[0065] The fastening element 8 can also be used as shown in the Figuren 3a, b shown, be formed as a captive fastening element with an axially extending collar 8a. In extension of the head 8b of the fastening element 8, a collar 8a can extend in the axial direction. This collar 8b has a diameter approximately corresponding to the diameter of the bore 4. In particular, the diameter is somewhat smaller, so that in the joined state according to Fig 3b the fastening element is mounted with play in hole 4.

[0066] After the collar 8a has been inserted into the bore 4, the collar 8a is bent outward at its front end. It is advantageous to provide a fold 4a in the bore 4. The collar 8a is thus bent into the fold 5a. The fastening element 8 is thus held captively on the flat part 2, but can still rotate in the bore 4.

[0067] Such a flat part can also be welded to a cable, as in Figuren 11 and 12 shown.

[0068] Fig. 4 shows a perspective view of a mounting unit 16. Two holes 20 are arranged symmetrically to a U-shaped recess 18.

[0069] The holding unit 16 is preferably a forged or cold-formed component made of metal. The U-shaped recess 18 is preferably formed to precisely match the shape of the fastening element 8 or the flat part 2, so that the holding unit 16 holds the fastening element 8 or the flat part 2 in a form-fitting manner from three sides. This is particularly advantageous when delicate work is performed on the flat part 2, 2a, such as the integral joining of parts using ultrasonic welding. In this case, alignment of the flat part 2 to the sonotrode and anvil is essential. The holding unit 16 precisely positions the flat part 2 before welding.

[0070] In one embodiment, the flat part 2 is formed as a cable lug, which is held in a form-fitting manner by the holding unit 16 and / or by the side shifter, preferably from three sides, and is positioned relative to the sonotrode 28 and the anvil 26, while joining parts 2, 2a or cable ends are fastened to the cable lug by means of ultrasonic welding.

[0071] The recess 18 is not limited to a U-shape; recesses of other shapes may also be present in the mounting unit 16. It is important that the mounting unit 16 has a structure complementary to the flat part 2, 2a or the fastening element 8, in particular the diameter of the head 8a of the fastening element 8.

[0072] For a more stable arrangement, the mounting unit 16 can also be fixed to the anvil 26. Fixing to stabilize the mounting unit 16 on the anvil 26 can be achieved, for example, via the two holes 20 arranged symmetrically to the recess 18. The fixation can then be realized using screws, threaded rods, bolts or dowels. Corresponding threads or holes must then also be located in the anvil 26. In addition to being fixed via two holes 20, the mounting unit 16 can also be fixed to the anvil 26 in other ways. For example, via just one hole or several holes arranged non-symmetrically to the recess. Alternatively, the mounting unit 16 can also be glued, riveted, or fixed to the anvil 26 in other ways.

[0073] Fig. 5 und Fig. 6 show the upper damping element 22 and lower damping element 24 in perspective. As shown, the first damping element 22 has a flat, cylindrical shape, whereas the second damping element 24 has a flat, cuboid shape with rounded corners.

[0074] The first damping element 22 has the task of limiting the movement of the fastening element 8 relative to the flat part 2, 2a and / or the joining part 10, 10a by applying a force perpendicular to the fastening element 8. Preferably, the damping element 22 should be arranged directly and immediately on the fastening element 8. Ideally, the damping element 22 has a surface shape that is as similar as possible to the surface of the fastening element 8 adjacent to the damping element 22.

[0075] Thus, in an embodiment in which a nut is used as the fastening element 8, a cylindrical shape with an outer diameter similar to the outer diameter of the nut would be ideal.

[0076] The second damping element 24 is expediently arranged on a surface of the anvil 26 facing the flat part 2, 2a, preferably between the anvil 26 and the flat part 2, 2a, in particular opposite the first damping element 22. In particular, the second damping element 24 can be held between the anvil 26 and the holding unit 16.

[0077] In the case of a fastening part 8 arranged on a flat part 2, 2a, in addition to positioning the flat part 2, 2a by a mounting unit 16 and in addition to restricting its mobility by means of a first damping element 22, supporting damping below the flat part 2, 2a, particularly opposite the first damping element 22, would be desirable. If no damping element were present there at all, it can be assumed that the surface of the flat part 2, 2a in the region of the contact surface with the anvil 26 would be damaged during ultrasonic welding.

[0078] According to one embodiment, the first 22 and second damping elements 24 can be formed from an elastic material, in particular polyurethane. In addition to polyurethanes, other elastic materials with good damping properties, such as rubber or plastic foams, could also be used.

[0079] Fig. 7 shows a sectional view of an arrangement of a form-fitting fastening element 8 with a sonotrode 28 arranged laterally, separately from a holding arm 30, using the example of a nut as the fastening element 8. As shown, the nut is held in a form-fitting manner by two joining parts 10 a and a flat part 2, 2 a. A first damping element is arranged on the nut and is held down on the nut by a holding arm. In addition, a second damping element 24 is inserted between the anvil 26 and the flat part 2, 2 a. A sonotrode 28 rests on a joining part 10 a, positioned laterally of the nut.

[0080] Due to the lateral arrangement of the sonotrode 28 as shown, one or more joining parts 10, 10a can be easily joined together by ultrasonic welding, while a form-fitting but rotatably held fastening element 8 is restricted in its relative movement to the flat part 2, 2a and / or joining part 10, 10a by a first damping element 24. The movement restriction can be achieved by a force applied perpendicularly to the surface of the damping element 22 by a holding arm 30.

[0081] In addition to a laterally arranged sonotrode 28, the joining parts 10 a can also be Fig. 8 The U-shaped sonotrode 28 shown is integrally connected to the flat part 2 a.

[0082] Fig. 8 shows a sectional view of a form-fitting fastening element 8 a with a U-shaped sonotrode 28 arranged on a holding arm 30 using the example of a screw as fastening element 8 a.

[0083] The use of a U-shaped sonotrode 28 is recommended when using two joining parts 10a, because this allows both joining parts 10a to be welded to the flat part 2a simultaneously. With the arrangement of the U-shaped sonotrode 28 on a holding arm 30 as shown, a corresponding damping device must be provided so that the mechanical vibrations transmitted to the sonotrode 28 are not transmitted to the holding arm 30. Alternatively, the U-shaped sonotrode 28 can therefore also be brought to the parts to be welded separately from the holding arm 30. Furthermore, it is also possible to arrange a holding arm, which can exert the force for damping the corresponding movable part on the first damping element, fixedly on the holding unit.

[0084] Fig. 9 shows a sectional view of the arrangement of a form-fitting fastening element 8 b with a U-shaped sonotrode 28 arranged on a holding arm 30 using the example of a bayonet lock as a fastening element.

[0085] In addition to a nut 8, a screw 8 a, or a bayonet lock 8 b, other fastening means can also be fixed to a flat part 2, 2 a, while these are held in a form-fitting and rotatable manner on a flat part 2, 2 a.

[0086] Fig. 10 shows a perspective view of an arrangement of a form-fitting fastening element 8 with a U-shaped sonotrode 28 arranged on a holding arm 30.

[0087] The embodiment in Fig. 10 shows a nut with a radially outward-facing collar 9 as an example of a fastening element 8. The nut is held simultaneously in a rotatable and form-fitting manner between two joining parts 10a and a flat part 2a, while the flat part 2a in turn rests on an anvil 26, dampened by a second damping element 24, and the nut 8 is positively enclosed on three sides by a holding unit 16 with a U-shaped recess. The holding unit 16 is fixed to the anvil 26 by two screws. The rotatably arranged fastening element 8 is additionally restricted in its movement relative to the flat part 2a and / or at least one joining part 10a by a first damping element 22. The force to be applied perpendicularly to the surface of the first damping element 22 for this purpose is applied by a holding arm 30 which is positioned above the first damping element 22.A U-shaped sonotrode 28 is arranged on the holding arm 30, which rests on the connection surfaces of the joining parts 10 a and can weld them to the flat part 2 a by means of an ultrasonic welding process.

[0088] Fig. 11 shows a sectional view of an arrangement of a captured fastening element 8 according to Fig. 3a, 3b A sonotrode 28 is provided at a first end of the flat part 2 in order to weld a cable end to the flat part 2. For this purpose, the bare cable ends, in particular made of aluminum, are welded to the flat part 2 using ultrasound. The vibration thus introduced into the flat part is transmitted to the fastening element 8. However, by pressing on the damping element 22, the fastening element 8 is dampened. At the same time, the contact pressure, e.g. 6 to 8 bar, of the damping element 22 on the fastening element 8 causes an elastic deformation of the flat part 2. This leads to a spring tension in the flat part 2, whereby this also functions as a vibration damper and dampens the USS vibrations.

[0089] A first damping element 22 is arranged on the fastening element 8 and is held down by a holding arm 30. Additionally, a second damping element 24 is inserted between the anvil 26 and the flat part 2, 2a. The second damping element 24 is preferably only in contact with the flat part 2, but not with the fastening element 8.

[0090] The fastening element 8 is restricted in its relative movement to the flat part 2, 2a and / or the joining part 10, 10a by a first damping element 24. The movement restriction can be achieved by a force applied perpendicularly to the surface of the damping element 22 by a holding arm 30.

[0091] It can also be seen that the damping element 22 is pressed into a blind hole in the holding arm 30.

[0092] Fig. 12 shows a perspective view of an arrangement of a captured fastening element 8 according to Fig. 3a, bwith a holding arm 30 which is arranged on side shifters 30a.

[0093] The flat part 2 is first inserted between the side slides 30a. The flat part 2 is aligned with the fastening element 8 via the holding unit 16. The side slides 30a are then moved together, thus holding the flat part 2 between the side slides. A sonotrode 28 is moved toward the anvil 26 on one side of the side slides 30a. This presses the sonotrode onto the cable ends to weld them to the flat part using USS.

[0094] At the same time, the holding arm 30 is moved toward the fastening element 8 at an angle to the movement of the side shifters 30a. As a result, the damping element 22 is pressed onto the fastening element 8, and the fastening element 8 is damped against vibrations.

[0095] The rotatably arranged fastening element 8 is restricted in its movement relative to the flat part 2a by the first damping element 22. The force to be applied perpendicularly to the surface of the first damping element 22 is applied by a holding arm 30 positioned above the first damping element 22. The contact pressure can be more than 1 bar, preferably less than 8 bar, in particular between 2 and 8 bar, preferably approximately 6 bar.

[0096] A particularly advantageous feature of the ultrasonic welding device is its modular design, consisting of at least one mounting element and / or at least one damping element. This allows for a particularly simple, purely mechanical implementation of the device into other existing systems. Due to the simple nature of the retrofit, no further subsequent modifications are necessary. A holding arm can also be permanently attached to the mounting unit, which can then be flexibly adjusted, similar to a screw clamp, to exert the necessary force on the first damping element to dampen the corresponding moving part.

Claims

1. A method of ultrasound welding a flat part with a joining part or a connection part, in which - a fastening element (8) is captively and in a free running manner arranged on a flat part, and - a damping element (22) is arranged at the fastening element (8) in such a way that a relative movement between the fastening element (8) and the flat part during the subsequent ultrasonic welding is restricted, wherein - the fastening element (8) is pressed against the flat part by means of the damping element (22) during the ultrasonic welding.

2. The method according to Claim 1, characterised in that the relative movement between the fastening element and the flat part and / or the joining part is restricted via a force applied by a holding arm perpendicularly to the damping element.

3. A system arranged for working the method according to one of claims 1 or 2 comprising - a flat part, - a fastening element (8) which is captively and in a free running manner arranged on a flat part, - a joining part or a connection part, which is welded by ultrasonic welding to the flat part and - an ultrasonic welding device with - a sonotrode (28) - an anvil (26), and - at least one damping element (22) that can be pressed on a fastening element (8), wherein - the damping element (22) is arranged at the fastening element (8) in such a way that a relative movement between the fastening element (8) and the flat part during the subsequent ultrasonic welding is restricted, wherein - the fastening element (8) is pressed against the flat part by means of the damping element (22) during the ultrasonic welding.

4. System according to Claim 3, characterised in that the fastening element (8) is arranged by at least one, preferably two joining parts on the flat part, wherein the joining part encompasses the fastening element (8) in part, preferably in full, or in that the fastening element (8) is captively arranged in an opening of the flat part.

5. System according to one of claims 3 to 4, characterised in that one of the contact surfaces between the sonotrode (28) and the at least one joining part or connecting part to be welded to the flat part is arranged laterally to the fastening element (8).

6. System according to one of claims 3 to 5, characterised in that - at least two side pushers preferably moving linearly towards one another are arranged in such a way that the flat part is held between the side pushers during welding and that on at least one of the side pushers a holding arm is arranged such that the holding arm is movable at an angle to the linear movement in the direction of the fastening element and on the holding arm at least one damping element (22) is arranged.

7. System according to one of claims 3 to 6, characterised in that - the at least one damping element (22) is arranged on a side of the holding arm facing towards the fastening element.

8. System according to one of claims 3 to 7, characterised in that at least one second damping element (24) is arranged on a surface of the anvil (26) facing towards the flat part, preferably between the anvil (26) and the flat part, particularly on the side of the flat part opposite the first damping element (22) and / or in that the second damping element is held between the anvil (26) and a holding unit9. System according to one of claims 3 to 8, characterised in that the first damping element (22) is arranged directly at or on the fastening element (8) and / in that the second damping element (24) is arranged on the flat part, wherein the second damping element (24) is preferably spaced apart from the fastening element (8).

10. System according to claim 7, characterised in that the first damping element (22) is arranged with a transition fit or a press fit on the holding arm, particularly in a blind hole in the holding arm.

11. System according to claim 7, characterised in that the holding arm pushes the damping element (22) against the fastening element (8) such that the flat part is elastically deformed and / or the holding arm is arranged such that a relative movement between the fastening element (8) and the flat part and / or the joining part during ultrasonic welding is restricted by a force applied perpendicularly to the surface of the first damping element (22).

12. System according to one of claims 3 to 11, characterised in that the fastening element (8) is a rotating fastening element, particularly a screw, a nut, a twist and lock fastener or a bayonet fastener and / or the fastening element (8) comprises a collar (9) pointing radially outwards, and running part of the way, preferably all the way round.

13. System according to one of claims 3 to 12, characterised in that the flat part is in the form of a cable connection element, particularly a cable shoe, wherein the cable shoe is preferably a friction-welding cable shoe, crimping cable shoe, or ultrasonic welding cable shoe.

14. System according to one of claims 3 to 13, characterised in that a holding unit surrounds the flat part in a positively locking manner on three sides and in the area of the contact surface with the fastening element (8) has a complementary structure and / or a holding unit is arranged form fit on the anvil (26), wherein the holding unit is preferably fixed to the anvil (26).