Multistage Welding Of Splices By Means Of An Ultrasonic Welding Device

Abstract

A method is described for welding a splice by way of an ultrasonic welding device, the ultrasonic welding device having a sonotrode for generating ultrasonic vibrations, an anvil, a first lateral element, a second lateral element and a compaction chamber, the height of which is adjustable by varying a distance between the sonotrode and the anvil and the width of which is adjustable by varying a distance between the first lateral element and the second lateral element.

Claims

1. A method for welding a splice by way of an ultrasonic welding device, wherein the ultrasonic welding device has a sonotrode for generating ultrasonic vibrations, an anvil, a first lateral element, a second lateral element and a compaction chamber, the height of which is adjustable by varying a distance between the sonotrode and the anvil and the width of which is adjustable by varying a distance between the first lateral element and the second lateral element, wherein the method comprises: arranging first conductor portions to be welded of at least two electrical conductors in the compaction chamber; adjusting the width of the compaction chamber to a predetermined value for a first welding operation; performing the first welding operation by activating the sonotrode and compressing the first conductor portions between the sonotrode and the anvil, wherein the first conductor portions are welded together to form a first splice; arranging a second conductor portion to be welded of at least one further electrical conductor and the first splice in the compaction chamber; adjusting the width of the compaction chamber to a predetermined value for a second welding operation, wherein the width of the compaction chamber for the second welding operation is greater by a predetermined tolerance value than the width of the compaction chamber for the first welding operation; and performing the second welding operation by reactivating 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.

2. The method according to claim 1, wherein the second conductor portion is arranged between the first splice and the sonotrode.

3. The method according to claim 1, wherein the predetermined tolerance value is at least 0.01 mm.

4. The method according to claim 1, wherein the predetermined tolerance value is at most 5 mm.

5. The method according to claim 1, wherein the second splice has a cross-sectional area of at least 3 mm.sup.2.

6. The method according to claim 1, wherein the second splice a nominal width of at least 2 mm.

7. The method according to claim 1, wherein the width of the compaction chamber for the first welding operation is equal to a nominal width of the first splice; and/or wherein the width for the compaction chamber for the second welding operation is equal to a nominal width of the second splice.

8. The method according to claim 7, wherein the width the compaction chamber for the first welding operation is equal to a difference between the nominal width of the second splice and the predetermined tolerance value.

9. The method according to claim 1, wherein a cross-sectional area of the second conductor portion is at least as large as a respective smallest cross-sectional area of the first conductor portions.

10. The method according to claim 1, further comprising: arranging a third conductor portion of at least one additional electrical conductor to be welded and the second splice in the compaction chamber; adjusting the width of the compaction chamber to a predetermined value for a third welding operation, wherein the width of the compaction chamber for the third welding operation is greater by a predetermined additional tolerance value than the width of the compaction chamber for the second welding operation; 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, wherein the second splice and the third conductor portion are welded together to form a third splice.

11. The method according to claim 1, wherein each of the electrical conductors is a partially sheathed strand and each of the conductor portions is an unsheathed portion of the strand.

12. A conductor bundle, produced in a method according to claim 1, wherein the conductor bundle comprises electrical conductors which are welded together in a splice; wherein the splice is divided in the direction of its height into two splice portions, each having a rectangular-shaped cross-section; wherein the two splice portions differ from each other in their average width by at least 0.01 mm.

13. The conductor bundle according to claim 12, wherein the splice is produced by ultrasonic welding.

14. The conductor bundle according to claim 12, wherein each of the electrical conductors is a partially sheathed strand and unsheathed portions of the strands are welded together to form the splice.

15. The method according to claim 1, wherein the predetermined tolerance value is at least 0.1 mm.

16. The method according to claim 1, wherein the predetermined tolerance value is at most 2 mm.

17. The method according to claim 1, wherein the second splice has a cross-sectional area of at least 50 mm.sup.2.

18. The method according to claim 1, wherein the second splice has a nominal width of at least 10 mm.

19. The conductor bundle according to claim 12, wherein the two splice portions differ from each other in their average width by at least 0.1 mm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Advantageous embodiments of the invention are further explained below with reference to the accompanying drawings, wherein neither the drawings nor the explanations are to be construed as limiting the invention in any way.

[0051] FIG. 1 shows a schematic illustration of an ultrasonic welding device according to an embodiment of the invention with opened compaction chamber before a first welding operation.

[0052] FIG. 2 shows the ultrasonic welding device of FIG. 1 with extended first lateral element.

[0053] FIG. 3 shows the ultrasonic welding device of FIG. 1 with closed compaction chamber during the first welding operation.

[0054] FIG. 4 shows the ultrasonic welding device of FIG. 1 with opened compaction chamber after the first welding operation and before a second welding operation.

[0055] FIG. 5 shows the ultrasonic welding device of FIG. 1 with closed compaction chamber during the second welding operation.

[0056] FIG. 6 shows a flow diagram of a method for welding a splice by means of an ultrasonic welding device according to an embodiment of the invention.

[0057] FIG. 7 show a schematic illustration of a conductor bundle according to an embodiment of the invention in cross-section.

[0058] FIG. 8 shows a lateral view of the conductor bundle of FIG. 7.

[0059] The figures are merely schematic and not to scale. Identical reference numerals in the various drawings denote identical features or features having the same effect.

DESCRIPTION OF ADVANTAGEOUS EMBODIMENTS

[0060] FIG. 1 shows a schematic illustration of an ultrasonic welding device 100 with a sonotrode 102 for generating ultrasonic vibrations, an anvil 104, a first lateral element 106, for example a sideshifter, and a second lateral element 108, for example a surface plate. The sonotrode 102, the anvil 104, the first lateral element 106 and the second lateral element 108 limit a compaction chamber 110, into which first conductor portions 112 of a plurality of electrical conductors 114 to be welded are inserted. Alternatively, only first conductor portions 112 of a single electrical conductor 114 may also be inserted, for compacting for example.

[0061] FIG. 1 shows the compaction chamber 110 by way of example in an opened state in which the compaction chamber 110 is open towards a side opposite the sonotrode 102 and is only limited on three sides by the sonotrode 102, the first lateral element 106 and the second lateral element 108. Thus the first conductor portions 112 may be inserted into the compaction chamber 110 from above, for example manually by an operator or automated by a gripping arm or the like. Contrary to the schematic illustration shown in FIG. 1, the lateral elements 106, 108 may also be adjusted such 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 sideshifter 106 may already be adjusted to a specific welding width before the electrical conductors 114 are inserted. In some cases, this makes insertion easier.

[0062] For example, the compaction chamber 110 may be closed by the anvil 104 on the side opposing the sonotrode 102, as is shown in FIGS. 3 and 5.

[0063] A width B of the compaction chamber 110 is predetermined by a distance between the first lateral element 106 and the second lateral element 108 in the x-direction and may be varied in the x-direction by moving the first lateral element 106 and/or the second lateral element 108. In FIG. 1, by way of example, only the first lateral element 106 is movable in the x-direction, the second lateral element 108 being fixed in the x-direction.

[0064] A height H of the compaction chamber 110 is predetermined by a distance between the sonotrode 102 and the anvil 104 in the y-direction in the closed state of the compaction chamber 110 and may be varied by moving the sonotrode 102 and/or the anvil 104 in the y-direction. The height H is drawn in FIGS. 3 and 5. In FIG. 1, by way of example, only the anvil 104 is movable in the y-direction, the sonotrode 102 being fixed in the y-direction. For example, the second lateral element 108 may be movable in the y-direction, while the anvil 104 may be mechanically coupled to the second lateral element 108. Thus the anvil 104 may be moved in the y-direction together with the second lateral element 108.

[0065] The electrical conductors 114 may each be individual wires of one or a plurality of cables. For example, each of the electrical conductors 114 may be partially sheathed with an insulating material. Each of the electrical conductors 114 may thus be an individual cable. The first conductor portions 112 may be unsheathed portions of such a cable. Alternatively, a plurality of the electrical conductors 114 may be combined into one or a plurality of strands. For example, all electrical conductors 114 may also be combined into a single strand. Such a strand may in turn be partially sheathed by an insulating material, i.e. it may be a cable.

[0066] The first conductor portions 112 may be arranged in multiple layers on a sonotrode surface 116 of the sonotrode 102. The ultrasonic vibrations may be coupled into the first conductor portions 112 via the sonotrode surface 116, causing the first conductor portions 112 to be bonded together in a positive substance jointing, i.e. welded into a splice.

[0067] The ultrasonic welding device 100 is configured to weld together the first conductor portions 112 in two consecutive welding operations.

[0068] For this purpose, the first lateral element 106 may be extended a short distance after insertion of the first conductor portions 112 to adjust the width B to a predetermined value for a first welding operation (see FIG. 2).

[0069] For example, the anvil 104 may additionally be lowered in the y-direction by lowering the second lateral element 108 and be moved in the x-direction towards the first lateral element 106. For example, the first lateral element 106 may act as a stop for the anvil 104 in the x-direction (see FIG. 3).

[0070] The sonotrode 102 is activated for welding and the first conductor portions 112 are compressed by means of the sonotrode 102 and the anvil 104. As a result, the first conductor portions 112 are welded together in a first splice 300 (see FIG. 3). In this case, the width of the first splice 300 may correspond to the width B of the compaction chamber 110. That is, the nominal width of the first splice 300 may be predetermined by the width B of the compaction chamber 110.

[0071] After welding the first splice 300, the compaction chamber 110 may be reopened, for example by retracting the first lateral element 106 and/or the anvil 104. The first splice 300 may now be removed from the compaction chamber 110 and second conductor portions 400 of a plurality of further electrical conductors 402 may be placed on the sonotrode surface 116 (see FIG. 4). The second conductor portions 400 may be unsheathed portions of one or a plurality of further cables. The first splice 300 is inserted onto the second conductor portions 400 so that the sonotrode surface 116 makes contact with the second conductor portions 400 but not with the first splice 300.

[0072] Before, during or after insertion of the second conductor portions 400 and the first splice 300, the width B is adjusted to a predetermined value for a second welding operation. The predetermined value for the second welding operation is greater by a predetermined tolerance value ΔB than the predetermined value for the first welding operation. The tolerance value ΔB is selected so that the first splice 300 has a slight clearance between the first lateral element 106 and the second lateral element 108. The clearance prevents the first splice 300 from jamming or tilting between the first lateral element 106 and the second lateral element 108 (see FIG. 4).

[0073] Subsequently, the second conductor portions 400 and the first splice 300 are welded together in the second welding operation to form a homogeneous, second splice 500 which may be significantly larger than the first splice 300 (see FIG. 5). Here, the width of the second splice 500 may correspond to the width B of the compaction chamber 110. That is, the nominal width of the second splice 500 may be predetermined by the width B of the compaction chamber 110.

[0074] It is possible that, in a third welding operation similar to the first and second welding operation, the second splice 500 will be welded with a third conductor portion of at least one additional electrical conductor to form a third splice.

[0075] FIG. 6 illustrates the basic sequence of the ultrasonic welding method described with reference to FIGS. 1 to 5.

[0076] In step S10, first conductor portions 112 of at least two electrical conductors 114 to be welded are arranged in the compaction chamber 110.

[0077] In step S20, the width B of the compaction chamber 110 is adjusted to the predetermined value for the first welding operation.

[0078] In step S30, the 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, the first conductor portions 112 being welded together to form the first splice 300.

[0079] In step S40, a second conductor portion 400 of at least one further electrical conductor 402 to be welded is arranged between the first splice 300 and the sonotrode 102 in the compaction chamber 110.

[0080] In step S50, the width B of the compaction chamber 110 is adjusted to the predetermined value for the second welding operation, the width B of the compaction chamber 110 for the second welding operation being greater by a predetermined tolerance value ΔB than the width B of the compaction chamber 110 for the first welding operation.

[0081] In step S60, the second welding operation is performed 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, the first splice 300 and the second conductor portion 400 being welded together to form the second splice 500.

[0082] The second splice 500 may have one or two steps on its lateral surfaces due to the different welding widths (see also FIG. 7).

[0083] FIG. 7 shows a cross-section through a conductor bundle 700 along a section line A-A shown in FIG. 8. The conductor bundle 700, for example, may have been produced by the method described above with reference to FIGS. 1 to 6 and comprise the conductors 114, 402 which are welded together in the second splice 500 (see also FIG. 8).

[0084] The second splice 500 is divided in the direction of its height H′ into a first splice portion 702 and a second splice portion 704, each having an approximately rectangular cross-section. The splice portions 702, 704 differ from each other in the direction of their width B′ by on average at least 0.01 mm, preferably by at least 0.1 mm.

[0085] The splice portions 702, 704 may be offset from each other in the direction of their width B′ such that a step forms on one or both sides of the second splice 500. In FIG. 7, the second splice 500 has, by way of example, a left-hand step 706 and a right-hand step 706′ which 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. The steps 706, 706′ may therefore be seen with the naked eye.

[0086] It may further be seen from FIG. 8 that each of the electrical conductors 114, 402 is a partially sheathed strand and the strands are welded together in an unsheathed region, comprising the conductor portions 112, 400, to form the second splice 500.

[0087] The width B′ of the widest splice portion 702, 704 may be equal to the nominal width of the second splice 500.

[0088] The height H′ may be equal to the nominal height of the second splice 500.

[0089] Finally, it should be noted that terms such as “having”, “comprising”, etc. do not exclude any other elements or steps and the term “a” or “one” does not exclude a plurality. It should further be pointed out that features or steps which have been 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 are not to be regarded as a limitation.

LIST OF REFERENCE NUMERALS

[0090] 100 Ultrasonic welding device [0091] 102 Sonotrode [0092] 104 Anvil [0093] 106 First lateral element [0094] 108 Second lateral element [0095] 110 Compaction chamber [0096] 112 First conductor portion [0097] 114 Electrical conductor [0098] 116 Sonotrode surface [0099] 300 First splice [0100] 400 Second conductor portion [0101] 402 Further electrical conductor [0102] 500 Second splice [0103] 700 Conductor bundle [0104] 702 First splice section [0105] 704 Second splice section [0106] 706 Left step [0107] 706′ Right step [0108] B Width of the compaction chamber [0109] B′ Width of the second splice [0110] ΔB Tolerance value [0111] H Height of the compaction chamber [0112] H′ Height of the second splice [0113] x x-direction [0114] y y-direction