Multi-stage welding of splices using ultrasonic welding equipment

Abstract

A method of welding a splice (500) using an ultrasonic welding apparatus (100) is described, the ultrasonic welding apparatus (100) having a sonotrode (102) for generating ultrasonic vibrations, an anvil (104), a first lateral element (106), a second lateral element (108), and a compression chamber (110), wherein the height (H) of the compression chamber is adjustable by changing the distance between the sonotrode (102) and the anvil (104), and the width (B) of the compression chamber is adjustable by changing the distance between the first lateral element and the second lateral element. The method includes the steps of placing a first conductor portion (112) to be welded of at least two conductors (114) in a compression chamber, adjusting the width of the compression chamber to a predetermined value for the first welding operation, activating a sonotrode and performing the first welding operation by compressing the first conductor portions between the sonotrode and anvil, whereby the first conductor portions are welded together to form a first splice (300), and placing a second conductor portion (400) to be welded of at least one other conductor (402) and the first conductor portion (400) in a compression chamber. The method includes placing the first splice in a compression chamber; adjusting the width of the compression chamber to a predetermined value for a second welding operation, wherein the width of the compression chamber for the second welding operation is greater than the width of the compression chamber for the first welding operation by a predetermined tolerance (ΔB); and performing the second welding operation by re-activating the sonotrode and compressing the first splice and the second conductor portion between the sonotrode and the anvil, wherein the first splice and the second conductor portion are welded together to form a second splice (500).

Description

[Technical field]

[0001] The present invention relates to a method for welding a splice using an ultrasonic welding device.The present invention further relates to a conductor bundle. [Background technology]

[0002] For a wide variety of technical applications, it may be necessary to join two components to one another in a mechanically secure and / or electrically conductive manner. For example, it may be necessary to join strands of a cable to one another in a mechanically and electrically conductive manner for various purposes. This makes it possible to produce wiring harnesses or cable looms that can be used, for example, to electrically connect electrical consumers in a vehicle to one another, to an energy source and / or to a control system.

[0003] So-called ultrasonic welding was developed to create material-to-material bonds between conductive components to give them high strength and good electrical conductivity. Ultrasonic welding is a special form of friction welding in which the components to be welded are placed in face-to-face contact with each other and moved against each other under low pressure and high frequency mechanical vibrations. The vibrations can be generated using a sonotrode, in which ultrasonic vibrations, typically with a frequency of 20 kHz to 50 kHz, are generated and transmitted to at least one of the joining partners. Plastic flow then allows the joining partners to penetrate or interlock with each other near the surface without necessarily melting the material of the joining partners. Thus, ultrasonic welding can be used to quickly and economically join the joining partners to each other with low impact. A weld where multiple electrical conductors are joined together is also called a splice.

[0004] Welding splices having a relatively large cross-section can be difficult in that the ultrasonic energy introduced by the sonotrode is generally introduced into the total volume of the splice only by the surfaces of the conductors to be welded that are in contact with the surface of the sonotrode, possibly resulting in uneven distribution of the ultrasonic energy and therefore uneven welding of the conductors.

[0005] When welding splices with a relatively large cross-section, a two-stage ultrasonic welding process may be used, in which, for example, a small splice is first welded and, in a separate step, it is welded to one or more other conductors to form a larger splice with the desired overall cross-section. Corresponding processes are described, for example, in WO 2015 / 007619 and DE 2011014801.

[0006] For example, DE 112014002908 A1 describes an ultrasonic welding process in which a wire bundle is welded in multiple welding operations and the wire bundle is rotated relative to a sonotrode between two welding operations. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] International Publication No. 2015 / 007619 [Patent Document 2] German Patent No. 2011014801 [Patent Document 3] DE 112014002908 A1 Summary of the Invention [Problem to be solved by the invention]

[0008] There may be a need for a method of welding splices with ultrasonic welding equipment that can consistently produce high quality splices, especially splices having relatively large cross sections. There may also be a need for a conductor bundle in which multiple high quality conductors are welded together to form a splice. [Means for solving the problem]

[0009] Such requirements may be met by the subject matter of the independent claims. Advantageous embodiments are defined in the dependent claims and in the following description.

[0010] A first aspect of the invention relates to a method of welding a splice with an ultrasonic welding apparatus, the ultrasonic welding apparatus comprising a sonotrode for generating ultrasonic vibrations, an anvil, a first lateral element, a second lateral element, and a compression chamber, the height of the compression chamber being adjustable by varying the distance between the sonotrode and the anvil, and the width of the compression chamber being adjustable by varying the distance between the first lateral element and the second lateral element. The method includes the following steps, which may be preferably performed in the indicated order: placing a first conductor portion of at least two conductors to be welded in a compression chamber; adjusting a width of the compression chamber to a predetermined value for the first welding operation; performing a first welding operation by activating the sonotrode and compressing the first conductor portion between the sonotrode and anvil, where the first conductor portions are welded together to form a first splice; placing a second conductor portion of at least one other conductor to be welded and the first splice in the compression chamber; adjusting a width of the compression chamber to a predetermined value for a second welding operation, where the width of the compression chamber for the second welding operation is greater than the width of the compression chamber for the first welding operation by a predetermined tolerance; and performing a second welding operation by reactivating the sonotrode and compressing the first splice and the second conductor portion between the sonotrode and anvil, where the first splice and the second conductor portions are welded together to form a second splice.

[0011] The sonotrode and the anvil may be arranged in the ultrasonic welding device such that they are movable relative to each other in at least one direction, for example to increase or decrease the vertical and / or horizontal distance between the sonotrode and the anvil. In this case, for example, the sonotrode may be fixed and the anvil may be movable. However, it is also possible that the sonotrode is movable and the anvil is fixed. Alternatively, both the sonotrode and the anvil may be movable.

[0012] The lateral elements can be, for example, side shifters (= lateral sliders) or platens (= contact plates). The first and second lateral elements can be arranged in the ultrasonic welding device to be movable relative to each other in at least one direction. For example, the first lateral element is horizontally movable and the second lateral element is horizontally fixed and vice versa. Alternatively, both lateral elements may be horizontally movable. It is also possible that at least one of the two lateral elements is additionally vertically movable.

[0013] The compression chamber may be limited on four different sides by the sonotrode, the anvil, the first lateral element and the second lateral element, at least during the welding operation. The compression chamber may be open on one or more other sides. For example, the compression chamber may be closed by the anvil at the top during the welding operation. By moving the anvil away, the compression chamber may be opened at the top, for example, to insert the conductor to be welded into the compression chamber before the welding operation or to remove the welded conductor from the compression chamber after the welding operation. For example, in order to facilitate the insertion or removal, in addition to moving the anvil away, at least one of the two lateral elements may be retracted so that the distance between the first and second lateral elements is increased accordingly.

[0014] The conductor may be a strand, i.e. a composite of several individual wires, or an individual wire of such a strand, i.e. a single solid conductor. The conductor may be partially coated with an electrically insulating material. The conductor part to be welded may thus be an uncoated part of the conductor, which part may be located at one end of the conductor or between both ends of the conductor. The conductor parts to be welded may have cross-sectional areas of different or the same size. The conductor may be made, for example, of metal or another conductive material. For example, the conductor may be a rigid part such as a connection terminal or a busbar.

[0015] A splice can generally be understood as a joint produced by welding together at least two joining partners. For example, in a first welding operation several strands, i.e. several composite wires, can be welded together to form the first splice. However, in a first welding operation, it is also possible that individual wires of one and the same strand are welded together to form the first splice, which is also called compacting. In this case, the first splice can be understood as a compacted part of this strand. In other words, the splice can include only one conductor (consisting of several individual wires) or several conductors.

[0016] As part of the process, a first conductor portion of at least two conductors to be welded is placed in the compression chamber. For this purpose, the compression chamber can be opened, for example, by moving away the anvil and / or at least one of the two side elements. At the same time, the width of the compression chamber can be adjusted to a predetermined value for the first welding operation. In the closed state, the compression chamber can be limited in its height by the sonotrode and the anvil and in its width by the two side elements.

[0017] The first splice and / or the second splice may have a rectangular-shaped cross section, i.e. at least approximately rectangular. Rectangular here means that the cross section is flattened on at least two opposite sides. For example, the cross section may be flattened on all four sides. However, for example barrel-shaped cross sections are also possible. For example, the dimensions of the rectangular-shaped cross section may correspond to the dimensions of the compression chamber in the closed state after welding. By activating the sonotrode, the sonotrode is vibrated and the welding energy is introduced into the conductor parts to be welded.

[0018] For example, the width of the compression chamber can be adjusted to the nominal width of the first splice or the nominal width of the second splice, which can be the desired maximum width of the first splice or the desired maximum width of the second splice.

[0019] The width of the compression chamber may be constant during the entire welding operation. However, it is also possible that the width of the compression chamber may be changed during welding.

[0020] The further conductor may be a further individual wire or a further strand, i.e. a welded or non-welded composite of further individual wires. It is also possible that the second conductor portion is a further splice in which a number of further conductors are welded together. The further splice may be produced, for example, by ultrasonic welding. For example, the second splice may be welded from the first splice of at least one non-welded strand and / or at least one compressed strand.

[0021] The method includes adjusting the width of the compression chamber to a predetermined value for the second welding operation, the width of the compression chamber for the second welding operation being larger than the width of the compression chamber for the first welding operation by a predetermined tolerance. The tolerance can be selected such that after adjusting the width of the compression chamber the first splice has a small gap between the first and second lateral elements. The gap prevents the first splice from tilting or getting stuck in the compression chamber. This makes it possible to achieve a defined distribution of forces over the entire cross section of the first splice in the subsequent welding operation. Thus, a very uniform, i.e. very durable and very conductive, welded joint can be produced. The gap can also reduce losses of welding force by preventing the first splice from coming into direct contact with the two lateral elements. The tolerance should not be selected too large so that material such as individual wires is not pushed past the first splice during the subsequent welding operation and / or the resulting splice does not have an excessively large step(s).

[0022] The width of the compression chamber for the second welding operation can be adjusted in the same way as for the first welding operation. For example, depending on the selected tolerances, the second splice can be divided in the direction of its height into two splice parts of different widths, each having a rectangular-shaped cross section, i.e. at least approximately rectangular cross section.

[0023] Tests have shown that in addition to reducing breakage and discoloration of single conductors, it was possible to increase the reliability of the process, especially due to a more uniform connector strength. A more uniform distribution of conductors across the width of the splice was also observed. It was also easier to reproduce the splice structure.

[0024] Without limiting the scope of the invention in any way, the ideas and possible features relating to embodiments of the invention may be deemed to be based, inter alia, on the ideas and findings described hereinafter.

[0025] According to one embodiment, the second conductor portion is placed between the first splice and the sonotrode. The first splice may first be removed from the compression chamber before the second conductor portion is placed. For this purpose, the compression chamber may be opened accordingly (see above). The second conductor portion may then be placed on the sonotrode. The first splice may then be placed on the second conductor portion such that direct contact between the first splice and the sonotrode is prevented. Thus, in the subsequent welding operation, the welding energy is introduced indirectly into the first splice via the second conductor portion. This makes it possible to prevent new high thermal and mechanical stresses on the first splice. Among other things, this may prevent or at least reduce breaks in the individual wires or uneven areas in the weld metal.

[0026] According to one embodiment, the predetermined tolerance is at least 0.01 mm. According to an alternative embodiment, the predetermined tolerance is at least 0.05 mm. According to another alternative embodiment, the predetermined tolerance is at least 0.1 mm.

[0027] According to one embodiment, the predetermined tolerance is at most 2 mm. According to an alternative embodiment, the predetermined tolerance is at most 5 mm.

[0028] By using a specified order of magnitude tolerance, on the one hand, it is possible to prevent the first splice from tilting or getting stuck in the compression chamber. On the other hand, it is possible to prevent material from being pushed past the first splice during the second welding operation, which would have a degrading effect on the welded joint and / or prevent the second splice from having an excessively large step. This simplifies further processing of the conductor bundle, for example, covering the second splice with a shrinkable tube.

[0029] According to one embodiment, the second splice is at least 3 mm 2 According to an alternative embodiment, the second splice has a cross-sectional area of ​​at least 20 mm2 According to another alternative embodiment, the second splice has a cross-sectional area of ​​at least 50 mm 2 has a cross-sectional area of

[0030] According to one embodiment, the second splice has a nominal width of at least 2 mm. According to an alternative embodiment, the second splice has a nominal width of at least 5 mm. According to another alternative embodiment, the second splice has a nominal width of at least 10 mm.

[0031] As already mentioned above, it has been observed that it may be difficult to use ultrasonic welding to form splices of relatively large diameter and / or having a relatively complex structure, since not sufficiently uniform joints between the conductors may result and / or damage may occur to the conductors, especially near the surface of the splice. Tests have shown that the method proposed here is particularly suitable for welding together conductors having relatively large conductor cross sections, such as those used for high current connections in electric or hybrid vehicles.

[0032] According to one embodiment, the width of the compression chamber for the first welding operation is equal to the nominal width of the first splice.

[0033] According to one embodiment, the width of the compression chamber for the second welding operation is equal to the nominal width of the second splice.

[0034] The nominal width of a splice can generally be understood as the desired maximum width of the splice. By adjusting the width of the compression chamber to the nominal width of the first or second splice, it can be ensured by simple means that the width of the first or second splice is equal to or less than this nominal width at the point of the maximum width of the splice.

[0035] According to one embodiment, the width of the compression chamber for the first welding operation is equal to the difference between the nominal width of the second splice and a predetermined tolerance. In other words, the nominal width of the first splice can be determined based on the nominal width of the second splice. The width difference between the two splices can be selected to be just large enough to prevent the first splice from tilting when it is inserted onto the second conductor portion for welding the second splice.

[0036] Depending on the material hardness of the joining partners and the welding parameters, the joining partners can be flattened over a partial region of the width of the compression chamber or over the entire width of the compression chamber during the welding operation. In the latter case, the first or second splice can be produced very easily and reproducibly in the desired final width by adjusting the width of the compression chamber accordingly.

[0037] According to one embodiment, the cross-sectional area of ​​the second conductor portion is at least as large as the smallest cross-sectional area of ​​the first conductor portion, such that relatively complex and / or relatively large splices can be constructed with only two welding operations.

[0038] According to one embodiment, the method further comprises the steps of placing the third conductor portion of the at least one additional conductor to be welded and the second splice in a compression chamber, adjusting the width of the compression chamber to a predetermined value for the third welding operation, the width of the compression chamber for the third welding operation being greater than the width of the compression chamber for the second welding operation by a predetermined additional tolerance, and performing the third welding operation by reactivating the sonotrode and compressing the second splice and the third conductor portion between the sonotrode and the anvil, the second splice and the third conductor portion of the at least one additional conductor being welded together to form the third splice. In some cases, it may be necessary to weld in three or more steps in order to be able to utilize the welding power most efficiently, such as when splices having a very large cross-sectional area and / or a very complex structure are to be produced.

[0039] For example, a third conductor portion can be placed between the second splice and the sonotrode. This prevents direct contact between the second splice and the sonotrode. Thus, in a subsequent welding operation, the welding energy is introduced indirectly into the second splice via the third conductor portion. This prevents new high thermal and mechanical stresses on the second splice. Among other things, this can prevent or at least reduce breaks in the individual wires or uneven areas in the weld metal.

[0040] Similar to the tolerances mentioned above, additional tolerances can be selected so that the second splice has a small gap between the first and second lateral elements after adjusting the width of the compression chamber, thus preventing the second splice from tilting or getting stuck in the compression chamber and ensuring a defined force distribution over the cross section of the second splice.

[0041] According to one embodiment, each of the conductors is a partially covered strand, such as a partially stripped cable, and each of the conductor portions is an uncovered portion of the strand. Thus, for example, a suitable cable assembly or harness for high current applications can be produced very efficiently with durable, highly conductive joints.

[0042] A second aspect of the invention relates to a conductor bundle comprising conductors welded together in a splice, the splice being divided in the direction of its height into two splice parts each having a rectangular-shaped cross section, i.e. at least approximately rectangular cross section, the two splice parts differing from each other by at least 0.01 mm or alternatively by at least 0.1 mm in the average width of the splice parts.

[0043] According to an alternative embodiment, the two splice portions may differ from each other in their average width by at least 0.05 mm.

[0044] The conductor bundle may preferably be produced by a process according to an embodiment of the first aspect of the invention, however, the conductor bundle may also be produced by another suitable welding process.

[0045] The average width can be understood as the average value of the relevant width of the splice section determined on the basis of a number of measurements. For example, a number of width values ​​can be measured for this purpose at several measurement points distributed over the relevant splice section. These width values ​​can then, for example, be used to calculate an arithmetic mean and / or median value as the average width.

[0046] In other words, the splice parts may form a step or be separated from each other by a step in the area where the splice parts are adjacent to each other in the direction of the height of the splice. Depending on the lateral offset of the two splice parts, the splice may have only one step on the opposite sides or may also have two steps. Such a step may extend substantially transversely to the direction of the height of the splice, in particular perpendicular to said direction. For example, the step may be visible to the naked eye. The step may be rounded, flattened or sharp. For example, the step may be rounded with a rounding radius larger than the maximum radius of the individual wires of the conductor bundle. In other words, the step may be wider than the maximum diameter of the individual wires of the conductor bundle. For example, the step may be at most 2 mm wide, preferably at most 5 mm wide. The total width of the step(s) may preferably be at least 0.05 mm, for example at least 0.1 mm. In particular, the overall width of the step(s) may correspond approximately to the tolerances adjusted during production of the splice, as described above.

[0047] A conductor bundle produced by a process according to an embodiment of the first aspect of the present invention may alternatively be free of such step(s).

[0048] According to one embodiment, the splice is produced by ultrasonic welding, so that the conductor bundle can be produced without melting the conductor material and therefore at a relatively low production cost compared to typical fusion welding processes.

[0049] According to one embodiment, each of the conductors is a partially coated strand, with the uncoated portions of the strands welded together to form the splice. In other words, each of the conductors may be a partially stripped cable. Each of the strands may be, for example, at least 10 mm 2As a result, the conductor bundles can be used for the protected conduction or distribution of electrical currents, in particular relatively high currents of, for example, at least 100 A, such as in electric and hybrid vehicles.

[0050] It should be noted that possible features and advantages of embodiments of the present invention are described in part with respect to a method of welding a splice with an ultrasonic welding device, in part with respect to an ultrasonic welding device capable of carrying out such a method, and in part with respect to a conductor bundle that may be produced by such a method. Those skilled in the art will recognize that features described for individual embodiments may be transferred in a similarly suitable manner to other embodiments, and may be adapted and / or interchanged to reach other embodiments of the present invention, possibly with synergistic effects.

[0051] Advantageous embodiments of the present invention are further described below with reference to the accompanying drawings, neither of which should be construed as limiting the invention in any way. [Brief description of the drawings]

[0052] [Figure 1] FIG. 2 is a schematic diagram of an ultrasonic welding apparatus according to one embodiment of the present invention with an open compression chamber prior to a first welding operation. [Diagram 2] FIG. 2 shows the ultrasonic welding device of FIG. 1 with an extended first lateral element. [Diagram 3] FIG. 2 illustrates the ultrasonic welding apparatus of FIG. 1 with the compression chamber closed during a first welding operation. [Figure 4] 2 illustrates the ultrasonic welding apparatus of FIG. 1 with the compression chamber open after a first welding operation and before a second welding operation. [Diagram 5] FIG. 2 illustrates the ultrasonic welding apparatus of FIG. 1 with the compression chamber closed during a second welding operation. [Figure 6] 4 is a flow diagram of a method of welding a splice using an ultrasonic welding device according to one embodiment of the present invention. [Figure 7]1 is a schematic cross-sectional view of a conductor bundle according to one embodiment of the present invention; [Figure 8] Figure 8 is a side view of the conductor bundle of Figure 7. The above figures are only schematic and are not drawn to scale. The same reference numbers in the various figures indicate the same features or features having the same effect. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0053] 1 shows a schematic diagram of an ultrasonic welding device 100 having a sonotrode 102 for generating ultrasonic vibrations, an anvil 104, a first lateral element 106, e.g. a side shifter, and a second lateral element 108, e.g. a face plate. The sonotrode 102, the anvil 104, the first lateral element 106, and the second lateral element 108 define a compression chamber 110 into which a first conductor portion 112 of a plurality of electrical conductors 114 to be welded is inserted. Alternatively, e.g. for compacting, only the first conductor portion 112 of a single electrical conductor 114 may be inserted.

[0054] FIG. 1 shows the compression chamber 110 in an open state as an example, in which the compression chamber 110 is open towards the opposite side of the sonotrode 102 and is limited on three sides by the sonotrode 102, the first lateral element 106 and the second lateral element 108. The first conductor portion 112 can thus be inserted into the compression chamber 110 from above, for example manually by an operator or automated, such as by a gripping arm. In contrast to the schematic diagram shown in FIG. 1, the lateral elements 106, 108 may be adjusted so that there is some air between the first conductor portion 112 and the respective end faces of the two lateral elements 106, 108 during insertion. Alternatively, the side shifter 106 may already be adjusted to a certain weld width before the conductor 114 is inserted. In some cases, this makes the insertion easier.

[0055] For example, the compression chamber 110 may be closed by anvil 104 on the side opposite the sonotrode 102, as shown in FIGS.

[0056] The width B of the compression chamber 110 is predetermined by the distance between the first lateral element 106 and the second lateral element 108 in the x-direction and can be varied by moving the first lateral element 106 and / or the second lateral element 108 in the x-direction. In Fig. 1, by way of example, only the first lateral element 106 is movable in the x-direction, while the second lateral element 108 is fixed in the x-direction.

[0057] The height H of the compression chamber 110 is predetermined by the distance between the sonotrode 102 and the anvil 104 in the y direction in the closed state of the compression chamber 110 and can be changed by moving the sonotrode 102 and / or the anvil 104 in the y direction. The height H is depicted in Fig. 3 and Fig. 5. In Fig. 1, by way of example, only the anvil 104 is movable in the y direction, while the sonotrode 102 is fixed in the y direction. For example, the second lateral element 108 may be movable in the y direction and the anvil 104 may be mechanically coupled to the second lateral element 108. Thus, the anvil 104 can be moved in the y direction together with the second lateral element 108.

[0058] Each of the conductors 114 may be an individual wire of one or more cables. For example, each of the conductors 114 may be partially covered with an insulating material. Thus, each of the conductors 114 may be a separate cable. The first conductor portion 112 may be an uncovered portion of such a cable. Alternatively, multiple conductors 114 may be grouped together in one or more strands. For example, all of the conductors 114 may be grouped together in a single strand. Such a strand may be partially covered by an insulating material, i.e., a cable.

[0059] The first conductor portions 112 may be arranged in multiple layers on a sonotrode surface 116 of the sonotrode 102. Ultrasonic vibrations may be coupled into the first conductor portions 112 via the sonotrode surface 116 to cause the first conductor portions 112 to be joined together with a positive substance jointing, i.e., welded into a splice.

[0060] Ultrasonic welding apparatus 100 is configured to weld first conductor portions 112 together in two sequential welding operations.

[0061] For this purpose, the first lateral element 106 can be extended a short distance after insertion of the first conductor portion 112 to adjust the width B to a predetermined value for the first welding operation (see FIG. 2).

[0062] For example, the anvil 104 can be lowered further in the y direction by lowering the second lateral element 108 and moved in the x direction towards the first lateral element 106. For example, the first lateral element 106 can act as a stop for the anvil 104 in the x direction (see FIG. 3).

[0063] The sonotrode 102 is actuated to weld, and the first conductor portions 112 are compressed by the sonotrode 102 and the anvil 104. As a result, the first conductor portions 112 are welded together in the first splice 300 (see FIG. 3 ). In this case, the width of the first splice 300 can correspond to the width B of the compression chamber 110. That is, the nominal width of the first splice 300 can be predetermined by the width B of the compression chamber 110.

[0064] After welding the first splice 300, the compression chamber 110 may be opened again, for example by retracting the first lateral element 106 and / or the anvil 104. Now, the first splice 300 may be removed from the compression chamber 110, and a second conductor portion 400 of a plurality of other conductors 402 may be placed on the sonotrode surface 116 (see FIG. 4). The second conductor portion 400 may be an unsheathed portion of one or more other cables. The first splice 300 is inserted into the second conductor portion 400 such that the sonotrode surface 116 contacts the second conductor portion 400 but does not contact the first splice 300.

[0065] Before, during, or after inserting the second conductor portion 400 and the first splice 300, the width B is adjusted to a predetermined value for the second welding operation. The predetermined value for the second welding operation is greater than the predetermined value for the first welding operation by a predetermined tolerance ΔB. The tolerance ΔB is selected so that the first splice 300 has a small gap between the first lateral element 106 and the second lateral element 108. The gap prevents the first splice 300 from getting jammed or tilted between the first lateral element 106 and the second lateral element 108 (see FIG. 4).

[0066] Subsequently, the second conductor portion 400 and the first splice 300 are welded together in a second welding operation to form a uniform second splice 500, which may be significantly larger than the first splice 300 (see FIG. 5 ), where the width of the second splice 500 may correspond to the width B of the compression chamber 110. That is, the nominal width of the second splice 500 may be predetermined by the width B of the compression chamber 110.

[0067] In a third welding operation similar to the first and second welding operations, the second splice 500 can be welded with a third conductor portion of at least one additional conductor to form a third splice.

[0068] FIG. 6 shows a basic sequence of the ultrasonic welding method described with reference to FIGS.

[0069] In step S10, first conductor portions 112 of at least two electrical conductors 114 to be welded are placed in a compression chamber 110.

[0070] In step S20, the width B of the compression chamber 110 may be adjusted to a predetermined value for the first welding operation.

[0071] In step S30, a first welding operation is performed by activating the sonotrode 102 and compressing the first conductor portions 112 between the sonotrode 102 and the anvil 104, such that the first conductor portions 112 are welded together to form a first splice 300.

[0072] In step S40, a second conductor portion 400 of at least one other conductor 402 to be welded is positioned between the first splice 300 and the sonotrode 102 within the compression chamber 110.

[0073] In step S50, the width B of the compression chamber 110 is adjusted to a predetermined value for the second welding operation, such that the width B of the compression chamber 110 for the second welding operation is greater than the width of the compression chamber 110 for the first welding operation by a predetermined tolerance value ΔB.

[0074] In step S60, a second welding operation is performed by re-activating the sonotrode 102 and compressing the first splice 300 and the second conductor portion 400 between the sonotrode 102 and the anvil 104, and the first splice 300 and the second conductor portion 400 are welded together to form the second splice 500.

[0075] The second splice 500 may have one or two steps on the outside surface of the splice due to the different weld widths (see also FIG. 7).

[0076] Figure 7 shows a cross-section of a conductor bundle 700 along section line AA shown in Figure 8. Conductor bundle 700 may be produced, for example, by the method described above with reference to Figures 1-6 and may include conductors 114, 402 welded together within a second splice 500 (see also Figure 8).

[0077] The second splice 500 is divided in the direction of a height H' of the splice into a first splice portion 702 and a second splice portion 704, each having a substantially rectangular cross section. The splice portions 702, 704 differ from each other in the direction of their widths B' by an average of at least 0.01 mm, preferably at least 0.1 mm.

[0078] The splice portions 702, 704 may be offset from one another along a width B' of the splice portions such that a step forms on one or both sides of the second splice 500. In FIG. 7, the second splice 500 illustratively has a left step 706 and a right step 706' that may have different widths depending on the offset of the splice portions 702, 704. For example, the sum of the respective widths of the steps 706, 706' may be at least 0.2 mm. Thus, the steps 706, 706' are visible to the naked eye.

[0079] As can be further seen from FIG. 8, each of the conductors 114 , 402 are partially coated strands, and the strands are welded together in the uncoated areas that include the conductor portions 112 , 400 to form the second splice 500 .

[0080] The width B′ of the widest splice portion 702 , 704 may be equal to the nominal width of the second splice 500 .

[0081] The height H′ may be equal to the nominal height of the second splice 500 .

[0082] Finally, it should be noted that terms such as "having" and "comprising" do not exclude other elements or steps, and the terms "a" or "one" do not exclude a plurality. It should further be pointed out that features or steps described with reference to one of the above exemplary embodiments may also be used in combination with other features or steps of other exemplary embodiments described above. Reference numerals in the claims should not be considered as limiting. [Explanation of symbols]

[0083] 100 Ultrasonic welding equipment 102 Sonotrode 104 Anvil 106 First Lateral Element 108 Second Lateral Element 110 Compression Chamber 112 First conductor portion 114 Conductors 116 Sonotrode Surface 300 First Splice 400 Second conductor part 402 Another Conductor 500 Second Splice 700 Conductor Bundle 702 First splice part 704 Second splice part 706 Left step 706' Right step B. Compression chamber width B' Width of second splice ΔB Tolerance H Compression chamber height H' Height of the second splice xx direction yy direction

Claims

1. A method of welding a splice (500) using an ultrasonic welding device (100), the ultrasonic welding device (100) having a sonotrode (102) for generating ultrasonic vibrations, an anvil (104), a first lateral element (106), a second lateral element (108), and a compression chamber (110), the height (H) of the compression chamber being adjustable by varying the distance between the sonotrode (102) and the anvil (104), and the width (B) of the compression chamber being adjustable by varying the distance between the first lateral element (106) and the second lateral element (108), the method comprising: placing a first conductor portion (112) to be welded of at least two electrical conductors (114) in the compression chamber (110); adjusting the width (B) of the compression chamber (110) to a predetermined value for a first welding operation; performing the first welding operation by activating the sonotrode (102) and compressing the first conductor portions (112) between the sonotrode (102) and the anvil (104), whereby the first conductor portions (112) are welded together to form a first splice (300); placing a second conductor portion (400) of at least one other conductor (402) to be welded and the first splice (300) in the compression chamber (110), the second conductor portion (400) being positioned between the first splice (300) and the sonotrode (102); adjusting a width (B) of the compression chamber (110) to a predetermined value for a second welding operation, where the width (B) of the compression chamber (110) for the second welding operation is greater than the width (B) of the compression chamber (110) for the first welding operation by a predetermined tolerance (ΔB), so that after adjusting the width of the compression chamber (110), the first splice (300) has a slight gap between the first side element (106) and the second side element (108); performing the second welding operation by reactivating the sonotrode (102) and compressing the first splice (300) and the second conductor portion (400) between the sonotrode (102) and the anvil (104), whereby the first splice (300) and the second conductor portion (400) are welded together to form a second splice (500); A method comprising:

2. the predetermined tolerance (ΔB) is at least 0.01 mm; or The predetermined tolerance (ΔB) is at least 0.1 mm; The method of claim 1.

3. The predetermined tolerance (ΔB) is at most 2 mm; or The predetermined tolerance (ΔB) is a maximum of 5 mm; The method according to claim 1 or 2.

4. The second splice (500) is at least 3 mm ２ or having a cross-sectional area of The second splice (500) is at least 50 mm ２ having a cross-sectional area of The method according to any one of claims 1 to 3.

5. the second splice (500) has a nominal width of at least 2 mm; or the second splice (500) has a nominal width of at least 10 mm; The method according to any one of claims 1 to 4.

6. the width (B) of the compression chamber (110) for the first welding operation is equal to the nominal width of the first splice (300); and / or a width (B) of the compression chamber (110) for the second welding operation is equal to the nominal width of the second splice (500); The method according to any one of claims 1 to 5.

7. a width (B) of the compression chamber (110) for the first welding operation is equal to the difference between the nominal width of the second splice (500) and the predetermined tolerance (ΔB); The method according to claim 6.

8. the cross-sectional area of ​​the second conductor portion (400) is at least as large as the smallest cross-sectional area of ​​the first conductor portion (112); The method according to any one of claims 1 to 7.

9. placing a third conductor portion of at least one additional conductor to be welded and said second splice (500) in said compression chamber (110); adjusting the width (B) of the compression chamber (110) to a predetermined value for a third welding operation, the width (B) of the compression chamber (110) for the third welding operation being greater than the width (B) of the compression chamber (110) for the second welding operation by a predetermined additional tolerance; performing the third welding operation by reactivating the sonotrode (102) and compressing the second splice (500) and the third conductor portion between the sonotrode (102) and the anvil (104), whereby the second splice (500) and the third conductor portion are welded together to form a third splice; The method of any one of claims 1 to 8, further comprising:

10. The method of any one of claims 1 to 9, wherein each of the conductors (114, 402) is a partially coated strand and each of the conductor portions (112, 400) is an uncoated portion of the strand.

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