EP3474391A1 - Method for joining at least two multi-strand leads by means of ultrasound - Google Patents

Abstract

Disclosed is a method for ultrasonically joining at least two stranded strands (30), comprising the steps of: a) fanning at least one of the strands (30), preferably all of the strands (30), in a fanning plane (E); b) before, during and / or after step a): inserting the strands (30) into a compression space (11) of an ultrasonic bonding device (10) so that at least two of the strands (30) are in contact substantially along the fanning plane (E) are with each other; c) bonding, in particular welding and / or soldering, the fanned strands (30) by means of ultrasound.

Description

The invention Method for connecting, in particular welding and / or soldering, at least two stranded strands by means of ultrasound.

A generic method is for example in the DE 197 23 215 A1 which discloses connection methods and connection arrangements for insulated lines or cables. Here, two insulated lines are crossed at a crossing angle, clamped between two resin plates and then subjected to ultrasound. Hereby, the core wires are to be loosely released or loosened, and the loosened or loosened core wires are gradually spread in a flat shape, and the lead wire parts of both insulated wires should be in contact with each other at plural points, thereby providing a connection state with an excellent electric current-carrying property and with to be obtained with a low contact resistance. Similar procedures are also in DE 197 23 242 A1 and DE 198 39 220 A1 disclosed.

Although the methods described in the documents mentioned result in a connection of two strands at a connection node. However, this connection node is electrically insulated due to the surrounding resin platelets, so it can not be electrically connected to other electrical conductors.

The WO 2015/007619 A1 discloses a method of manufacturing a knot by welding a first strand comprising at least one single wire with a second strand of different materials comprising at least one single wire in a height and width adjustable compression space of an ultrasonic welding apparatus. The at least one first strand is inserted into the compression space and their individual wires then welded to a sub-node. Subsequently, the compression space is opened, placed at least a second strand in the compression space on the sub-node and then welded after closing the compression space the at least one second strand with the sub-node.

In an in WO 2015/007619 A1 described embodiment, a first strand is inserted without special pretreatment in the compression space and then adjusted its width, whereby the first strand is compressed in the horizontal direction. By this horizontal compression, however, the also substantially horizontal connection surface is reduced, at which the two strands come into contact with each other and welded together. In addition, it may happen that the first strand frayed in the horizontal compression in an uncontrolled manner in the vertical direction, whereby the welding energy can not be reliably homogeneously introduced. The result is connections with pull-off forces and peeling forces, which are low and also subject to significant fluctuations. Overall, this method is therefore error-prone.

It is therefore an object of the present invention to provide a method for connecting at least two stranded strands by means of ultrasound, by which the above-mentioned disadvantages are at least partially eliminated. In particular, the connecting nodes formed between the strands should not be electrically insulated and / or take-off forces and peeling forces should be achieved which are as large as possible and moreover are subject to as small fluctuations as possible. This should be possible in particular for the largest possible strand cross sections.

1. a) Auffächern mindestens einer der Litzen, bevorzugt sämtlicher Litzen, in einer Auffächerungsebene,
2. b) vor, während und/oder nach Schritt a): Einlegen der Litzen in einen Verdichtungsraum einer Ultraschallverbindungsvorrichtung, so dass mindestens zwei der Litzen im Wesentlichen entlang der Auffächerungsebene in Kontakt miteinander sind,
3. c) Verbinden, insbesondere Verschweissen und/oder Verlöten, der aufgefächerten Litzen mittels Ultraschalls.

These and other objects are achieved by a method according to the invention for joining at least two stranded strands solved by ultrasound, which contains the following steps:

1. a) fanning out at least one of the strands, preferably all the strands, in a fanning plane,
2. b) before, during and / or after step a): inserting the strands into a compression space of an ultrasonic bonding device so that at least two of the strands are in contact with each other substantially along the fanning plane,
3. c) bonding, in particular welding and / or soldering, the fanned strands by means of ultrasound.

A fanning out of a stranded strand in step a) is understood here and below to mean that a width of the stranded cross-section of the strand running parallel to the fanning-out plane is increased, for example by at least 10%, preferably at least 20%, particularly preferably at least 25%.

Due to the fanning out in step a) is in contrast to the above WO 2015/007619 A1 reaches an enlarged connection surface at which the at least two strands come into contact with each other and can be connected together in the later step c). In addition, the positioning of the strands in the compression space is simpler and more defined than is possible, for example, with strands which have a substantially circular cross-section and are stacked one above the other in the compression space. In addition, the individual wires of the fanned strands when connecting in step c) interlock with each other, which also contributes to increasing the stability of the connection.

Before, during or after step a), the strands are inserted into a compression space of an ultrasonic connecting device, so that at least two of the strands substantially along the fanning level are in contact with each other. The ultrasonic connecting device may be an ultrasonic welding device. In one variant, the strands are first inserted into the compression space and then fanned out. For this purpose, a tool can be used, which can be introduced directly into the compression chamber. It is conceivable that initially only a first strand is inserted into the compression space and then fanned there and then placed a second strand in the compression space and on the first already fanned strand and then fanned out as well. In another variant, the strands are first fanned out and then inserted into the compression space. In addition, it is within the scope of the invention that a first strand is fanned out after insertion into the compression space and a second strand is fanned out already prior to insertion into the compression space.

By means of this method according to the invention, the strands can be connected to a very homogeneous distribution of the bonding energy, in particular the welding energy and / or the soldering energy. This results in high and also uniformly high pull-off forces and peeling forces, as can be determined in an optional, subsequent quality assessment. For example, in some experiments with the method according to the invention, the pull-off forces could be increased by up to 30%. The process is thus less error-prone. Optically, the connection achieved a high quality.

Furthermore, due to the fanning, the connection force and connection energy required for the connection can be reduced, since part of the deformation work has already been introduced into the strands during the fanning out. A reduction of the connection force and connection energy required for the connection is particularly advantageous for strands with large strand cross-sections. For example, at least one of the strands, preferably all strands have a strand cross-section of more than 1 mm ² , preferably more than 10 mm ² , particularly preferably more than 25 mm ² . The total strand cross-section of the strands may be more than 4 mm ² , preferably more than 40 mm ² , more preferably more than 100 mm ² . Alternatively, while maintaining the connection energy, in particular the welding energy, the duration of the process can be reduced.

Advantageously, in step a) at least one of the strands, preferably all the strands are additionally compressed. Compressing the strand is understood here and below as meaning that a height of the strand cross section of the strand perpendicular to the fanning plane is reduced, for example by at least 10%, preferably at least 20%, particularly preferably at least 25%. By this compression, the strands are given a shape that is subject to even smaller tolerances, whereby even more homogeneous properties of the resulting connection nodes can be achieved. The compression can be perpendicular or oblique to the fanning plane.

For fanning and optionally for compression in step a), a per se known tool can be used, such as a press, which may optionally contain a suitable tool attachment. The press can be a pneumatically driven crimping pliers. The tool may be installed on or in the ultrasonic bonding device. It can also be a separate tool.

At least one of the strands, preferably all of the strands may be made of aluminum or copper or another non-ferrous metal. In particular, at least one first strands may consist of copper and at least one second strands of aluminum.

In a structurally simple and effective embodiment of the compression space is limited by a working surface of an excitable ultrasonic vibrations sonotrode, a work surface an anvil and side surfaces of two side boundary elements. Particularly preferably, the strands are inserted into the compression space such that the fanning plane runs parallel to the working surface of the sonotrode and to the working surface of the anvil. If the sonotrode and the anvil are pressed against each other in step c) with a connecting force which is perpendicular to their working surfaces, the connecting force also runs perpendicular to the fanning plane. This results in a particularly stable connection. A particularly stable connection also results if at least in step c) all strands are arranged along a direction perpendicular to the fanning plane. Thus, for example, no two strands are adjacent in a direction parallel to the fanning plane.

It is particularly efficient if none of the strands is welded or soldered before step c). The strands are therefore welded and / or soldered together only in step c), which leads to shorter process times.

The strands can be arranged at least in step c) at an angle and connected to each other, which is less than 30 °, preferably less than 15 °, more preferably less than 5 °.

Figur 1:

vier ohne erfindungsgemässes vorheriges Auffächern verbundene Litzen sowie vier nach erfindungsgemässem vorherigem Auffächern verbundene Litzen, jeweils in einer ersten Anordnung, in einer perspektivischen Ansicht;

Figur 2a:

die vier ohne erfindungsgemässes vorheriges Auffächern verbundene Litzen gemäss Figur 1 in einer Schnittansicht durch einen Verbindungsknoten;

Figur 2b:

die vier nach erfindungsgemässem vorherigem Auffächern verbundene Litzen gemäss Figur 1 in einer Schnittansicht durch einen Verbindungsknoten;

Figur 3:

vier ohne erfindungsgemässes vorheriges Auffächern verbundene Litzen in einer zweiten Anordnung, in einer perspektivischen Ansicht;

Figur 4:

die vier ohne erfindungsgemässes vorheriges Auffächern verbundenen Litzen gemäss Figur 3 in einer Schnittansicht durch einen Verbindungsknoten;

Figur 5:

ein Werkzeug zum erfindungsgemässen Auffächern einer darin eingelegten Litze vor dem Auffächern;

Figur 6:

das Werkzeug mit der darin eingelegten Litze nach dem Auffächern.

Below, the invention will be explained in more detail with reference to embodiments and drawings. Show

FIG. 1:

four strands connected without prior fanning according to the invention and four strands connected according to the invention of prior fanning, each in a first arrangement, in a perspective view;

FIG. 2a:

the four according to the invention without prior fanning connected strands according to FIG. 1 in a sectional view through a connection node;

FIG. 2b:

in accordance with the four strands connected according to the invention in accordance with the invention of prior fanning FIG. 1 in a sectional view through a connection node;

FIG. 3:

four strands connected without previous prior fanning in a second arrangement, in a perspective view;

FIG. 4:

the four without inventive prior fanning connected strands according to FIG. 3 in a sectional view through a connection node;

FIG. 5:

a tool for fan-out according to the invention of a strand inserted therein prior to fanning;

FIG. 6:

the tool with the inserted wire after fanning.

In FIG. 1 each four strands 30 are shown on the left and right, each of which are arranged along one direction and have parallel longitudinal axes, that are arranged at an angle of 0 ° to each other. The strands 30 may for example consist of aluminum or copper or another non-ferrous metal and have a strand cross section of 25 mm ² , so that in each case a total strand cross section of 100 mm ² results.

In the FIGS. 2a, 2b and 4 a known per se ultrasonic welding device 10 for welding the strands 30 is shown. This contains a compression space 11, which is bounded by the working surface 13 of a sonotrode 12, the working surface 15 of an anvil 14 and side surfaces 18 of two side boundary elements 16, 17. The left side limiting element 16 is in the horizontal direction relative to the sonotrode 12 slidably disposed while the right side limiting element 17 is slidably disposed in the vertical direction relative to the sonotrode 12. The anvil 14 is slidably disposed in the horizontal direction relative to the right side limiting element 17. As a result, a width and a height of the compression space 11 can be adjusted in a manner known per se.

The four in FIG. 1 left and in FIG. 2a The strands 30 shown have not previously been fanned out according to a conventional method and therefore still have their original, substantially circular strand cross-section. In this form and arrangement, the strands are difficult, but at least not reliably positionable in the compression space 11 in a defined manner. In addition, the connection surface at which the strands 30 come into contact with each other and welded together, is very small.

On the other hand, the four in FIG. 1 right and in FIG. 2b to be seen strands 30 according to the inventive method in a step a) previously fanned out in a vertically arranged fanning plane E and compressed, for example, with a in the FIGS. 5 and 6 shown tool 50; ie a parallel to the fanning plane E extending width b of the strand cross section of the strand 30 was increased, and a perpendicular to the fanning plane E running height h of the strand cross section of the strands 30 has been reduced. The strands 30 were placed in a step b) on the working surface 13 of the sonotrode 12 that the fanning plane E parallel to the working surface 13 of the sonotrode 12 and the working surface 15 of the anvil 14 extends. The sonotrode 12 and the anvil 14 are pressed against each other in step c) with a connecting force which is perpendicular to their working surfaces 13, 15, so that the connecting force is also perpendicular to the fanning planes E. All Four strands 30 are arranged along this direction of the connection force.

As by comparing the FIGS. 2a and 2b can be seen, the connection surface at which the strands 30 come into contact with each other and welded together, significantly larger when the strands 30 as in FIG. 2b previously fanned out. The ultrasonic vibrations introduced by the sonotrode 12 can thus penetrate into and penetrate the composite of the strands 30 more efficiently and more homogeneously. As a result, the strands 30 can be connected to a very homogeneous distribution of the welding energy. Consequently, there are high and also consistently high pull-off forces and peel forces, as can be determined in an optional, subsequent quality assessment. The process is thus less error-prone. Furthermore, due to the fanning, the connection force and welding energy required for the welding can be reduced, which is advantageous in particular for strands 30 with large strand cross-sections. Optically, the connection achieved a high quality.

In FIG. 3 four strands 30 are shown in a second arrangement, in which two lower strands 30 side by side and above two upper strands 30 are arranged side by side. Analogous to the FIGS. 1 left and 2a, the four were in the FIGS. 3 and 4 shown strands 30 according to a conventional method not previously fanned and therefore still have their original, substantially circular Litzenquerschnitt. In the FIG. 4 each of strands 30 shown side by side are insufficiently connected to each other, since their connection surfaces are parallel to the direction of the connecting force, in which the sonotrode 12 and the anvil 14 are pressed against each other. In addition, there is a gap 31 between the strands 30. At this point, the weld joint can be particularly unstable.

In the FIGS. 5 and 6 a tool 50 suitable for fanning out and compressing according to the invention is shown. This includes a stand 51 with a support surface 52 for one or more strands 30 and a ram 53 with a parallel to the support surface 52 arranged pressing surface 54. The ram 53 is pneumatically relative to the stand 51 in a direction R movable at an angle β to Support surface 52 and the pressing surface 54 extends. As a result, in the inventive method step a) the strand 30 is clamped between the support surface 52 and the pressing surface 54 and thus fanned out in a defined by the support surface 52 and the pressing surface 54 fanning plane E and compressed at an angle β to it.

Claims (11)

Method for connecting at least two stranded strands (30) by means of ultrasound, comprising the steps: a) fanning at least one of the strands (30), preferably all of the strands (30), in a fanning plane (E), b) before, during and / or after step a): inserting the strands (30) into a compression space (11) of an ultrasonic bonding device (10) so that at least two of the strands (30) are in contact substantially along the fanning plane (E) are with each other, c) bonding, in particular welding and / or soldering, the fanned strands (30) by means of ultrasound. Process according to claim 1,
wherein in step a) at least one of the strands (30), preferably all the strands (30) are additionally compressed. Method according to one of the preceding claims,
wherein in step a) a perpendicular to the fanning plane (E) extending height (h) of the strand cross section of at least one of the strands (30), preferably all strands (30) by at least 10%, preferably at least 20%, particularly preferably at least 25% is reduced , Method according to one of the preceding claims,
wherein in step a) a parallel to the fanning plane (E) extending width (b) of the strand cross section of at least one of the strands (30), preferably all of the strands (30) is increased by at least 10%, preferably at least 20%, more preferably at least 25%. Method according to one of the preceding claims,
wherein at least one of the strands (30), preferably all the strands (30) have a strand cross-section of more than 1 mm ² , preferably more than 10 mm ² , more preferably more than 25 mm ² . Method according to one of the preceding claims,
wherein at least one of the strands (30), preferably all strands (30) made of aluminum or copper or another non-ferrous metal. Method according to one of the preceding claims,
wherein the compression space (11) is delimited by a working surface (13) of a sonotrode (12) which can be excited to cause ultrasonic vibrations, a working surface (15) of an anvil (14) and side surfaces (18) of two lateral boundary elements (16, 17). Process according to claim 7,
wherein the fanning plane (E) is parallel to the working surface (13) of the sonotrode (12) and to the working surface (15) of the anvil (14). Method according to one of the preceding claims,
wherein at least in step c) all the strands (30) are arranged along a direction perpendicular to the fanning plane (E) extending direction. Method according to one of the preceding claims,
wherein before step c) none of the strands (30) is welded or soldered. Method according to one of the preceding claims,
wherein the strands (30) at least in step c) are arranged at an angle and interconnected, the less than 30 °, preferably less than 10 °, more preferably less than 5 °.

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