EP3761452A1 - Electrical connection between an electric conductor and a contact element - Google Patents

Abstract

Method for establishing an electrical connection between an electrical conductor (5) comprising several individual wires (9) and a contact element (2), the electrical conductor (5) being arranged in a contact section (4) of the contact element (2) and subsequently the contact section (4) and the electrical conductor (5) are pressed together so that the contact section (4) engages around the electrical conductor (5), and with laser irradiation of the contact section (4) at least two elongated welded connections (14) spaced apart from one another between the contact section ( 4) and the electrical conductor (5), the elongated welded connections (14) each extending in an irradiation direction from an irradiated area (13) of the contact section (4) at least in sections into the electrical conductor (5).

Description

FIELD OF THE INVENTION

The invention relates to a method for producing an electrical connection between an electrical conductor comprising several individual wires and a contact element, the electrical conductor being arranged in a contact section of the contact element and subsequently the contact section and the electrical conductor being pressed together so that the contact section is the electrical conductor encompasses.

The invention further relates to a corresponding device for establishing an electrical connection and a unit composed of an electrical conductor comprising several individual wires and a contact element.

The contact element is formed, for example, by a cable lug, such as a crimp cable lug, or a cable sleeve, such as a crimp sleeve.

STATE OF THE ART

There are known connection methods for electrically connecting an electrical cable to a contact element, in which a cable crimping section which is provided on the contact element is brought into press contact with an electrical conductor of the electrical cable. In such a crimped contact connection, if the conductor of the electrical cable is made up of a plurality of individual wires, the conductor wires located on the outer circumference are brought into direct contact with the contact element and power conduction is easy to achieve for them. The individual wires that are arranged in the center of the conductor can be connected to the Contact element can only be brought into conductive contact via the individual wires that are located on the outer circumference.

In order to establish a corresponding cross contact between the individual wires located inside the conductor to other individual wires and on to the contact element, for example DE 10358153 A1 proposed to weld the individual wires to one another and to the contact element by means of a laser in addition to crimping. It is provided there that several areas of the conductor are welded one after the other and overlapping. During the first welding step, rapid heating takes place through the application of the laser beam and an explosive distribution of material within the conductor. A subsequent welded area covers the first welded area and uses the resulting increased temperature condition, in that there is no rapid heating by the laser beam during the second and subsequent welding steps. The material gradually melts so that explosive spreading can be prevented. However, the disadvantage of this method is that explosive distribution can still occur in the first welding step.

OBJECT OF THE INVENTION

It is therefore an object of the invention to overcome the disadvantages of the prior art and to propose a method in which the risk of explosive distribution is reduced and a transverse conductivity can nevertheless be established between individual wires.

DISCLOSURE OF THE INVENTION

This object is achieved by a method according to claim 1. The starting point for this is a method for establishing an electrical connection between a number of individual wires comprehensive electrical conductor and a contact element, wherein the electrical conductor is arranged in a contact section of the contact element and subsequently the contact section and the electrical conductor are pressed together so that the contact section engages around the electrical conductor.

According to the invention it is provided that by means of a laser irradiation of the contact section at least two elongated welded connections are made between the contact section and the electrical conductor, the elongated welded connections each extending from an irradiated area of the contact section at least in sections into the electrical conductor.

By producing at least two, but usually several elongated welded joints, which each extend from the surface of the contact section through this and further into the interior of the conductor, but are spaced apart, the energy input is reduced compared to conventional welding processes because the material should not be melted between the elongated welded joints according to the invention.

Elongated welded connections according to the present invention have a greater extent in their longitudinal direction, that is to say in the direction of irradiation, than in the width direction. The length is preferably a multiple of the average width or its diameter, in particular the elongated welded connections can be rod-shaped, that is to say have an approximately constant diameter over their length.

Such elongated, in particular rod-shaped, welded connections can be produced by deep laser welding, where high beam intensities in the melt in the radiation direction form a vapor capillary deep into the workpiece. The material is thereby too melted in depth, the melting zone is usually more deep than wide.

After the laser irradiation, the irradiated area is generally visible as an approximately round area on the surface of the contact area, corresponding to the diameter of the laser beam and the material of the contact area melted all around.

Due to the concentration of the molten material per so-called laser puncture, i.e. per area of the later elongated welded joint, in a very narrow area, only a little material is liquefied relative to conventional welding methods, which reduces the risk of explosive distribution of material.

The deeper the elongated welded connections reach into the conductor, the more individual wires are connected to the elongated welded connections and the better the transverse conductivity.

One embodiment variant of the invention provides that the laser irradiation is carried out in such a way that the elongated welded connection extends in the direction of irradiation through the entire cross section of the pressed electrical conductor. The elongated welded connections should therefore best extend in their longitudinal direction from the irradiated area of the contact section through the conductor to that area of the contact section guided around the conductor which is opposite the irradiated area. Then the individual wires captured by this welded connection would even be connected to the contact section at two points.

By varying the energy introduced into the material by the laser and / or through the duration of the laser irradiation, it is possible to set how deep the laser penetrates the material.

One embodiment variant of the invention provides that several elongated welded connections, preferably all of them, are produced one after the other by the same source of laser irradiation. With a source, i.e. a laser, for example, appropriate optical deflections (e.g. mirrors, etc.) can be used to reach all desired irradiated areas from a source without the contact element having to be moved relative to the source.

One embodiment variant of the invention provides that several elongated welded connections are produced in irradiated areas that are regularly spaced from one another. The irradiated areas, usually visible as small, approximately circular points on the surface of the contact area, are thus arranged at a distance from one another on the surface of the contact area. As a result of the regular arrangement, regular penetration of the conductor and thus the connection of the individual wires of the conductor with elongated welded connections can be ensured. The irradiated areas can be arranged on the surface of the contact area according to a grid, for example. The fact that the individual wires are usually also twisted and that their position in the conductor cross-section change over their length also contributes to the contacting of all individual wires.

In particular, but not only in the case of a grid-like arrangement of the irradiated areas, it can be provided that one irradiated area is offset from another irradiated area normal to the longitudinal direction of the individual wires. This ensures that not only one and the same individual wire is always contacted by different elongated welded connections that follow one another in the longitudinal direction of the individual wires and that other adjacent individual wires are not.

It can be provided that the degree of compression of the individual wires in a longitudinal region of the contact element in which there are no irradiated regions is less than in FIG a longitudinal area of the contact element where irradiated areas are located.

The degree of crimping indicates the ratio of conductor cross-section after crimping (or crimping) to conductor cross-section before crimping (or crimping). A compression rate of 100% means that the conductor cross-section has not been reduced at all by the compression (or crimping), but has remained the same. A compression ratio of 80% means that the conductor cross-section has been reduced to 80% of the original conductor cross-section as a result of the compression (or crimping).

It can now be provided that the contact section is divided into two longitudinal areas transversely to the longitudinal direction of the individual wires. In one longitudinal area the conductor is only pressed, in the other longitudinal area the conductor is pressed and additionally irradiated with the laser according to the invention. In the longitudinal area, where the laser is also irradiated, it is advantageous if there are as many spaces as possible between the individual wires, i.e. an open rope structure is ensured, which acts as a ventilation channel when a melt pressure builds up during the laser welding process. This measure stabilizes the laser welding process, which means, for example, if there is an emulsion residue between the pressed wires, this can lead to evaporation of this emulsion when the energy is introduced, which negatively affects the laser welding result. If you now make sure that the loose rope structure has a kind of chimney effect, the evaporation of this emulsion residue has no negative influence on the result.

One possibility of producing a different degree of compression is that the different degree of compression is produced by a compression tool with a stepped support surface. The length of the two Each step corresponds to a longitudinal section of the contact section. The different heights of the support surface relative to the contact section of the contact element have the effect that the conductor is compressed to different degrees in the two longitudinal sections of the contact element.

Another possibility for producing a different degree of compression is that the different degree of compression is produced by a contact section with cable lug claws of different lengths in the transverse direction. That longitudinal section, which is to be pressed together more, then has longer cable lug claws, i.e. more material that is pressed towards the conductor during pressing. In this way, a different height or compression of the conductor can be achieved even with a flat contact surface of the pressing tool.

It is also possible to use stepped contact surfaces and different long cable lug claws at the same time.

With regard to an open rope structure of the individual wires, it is advantageous if the degree of compression of the individual wires in a longitudinal area of the contact element where the irradiated areas are located is greater than 70%.

In order to avoid unnecessary processing steps, such as bringing the pressed conductor to a welding station, it can be provided that the laser irradiation takes place in the tool in which the pressing takes place.

In particular, it can be provided that the position of the pressed electrical conductor is not changed between pressing and laser irradiation. The pressed electrical conductor remains in the tool after pressing and is also welded there with the laser.

It can be provided that the production of an elongated welded connection takes less than 50 ms, in particular less than 40 ms, e.g. around 30 ms.

It can be provided that the contact section is provided with a nickel coating, at least in the area where it touches the electrical conductor. The nickel layer, on the one hand, provides protection against corrosion between the conductor and the contact section and, on the other hand, increases the energy absorption during laser welding.

A device for performing the method according to the invention, that is to say for producing an electrical connection between an electrical conductor comprising several individual wires and a contact element, comprises a pressing tool with which the electrical conductor arranged in a contact section of the contact element can be pressed with the contact element, so that the contact section encompasses the electrical conductor, and is characterized in that a device for laser irradiation is provided, which is designed to produce at least two elongated welded connections between the contact section and the electrical conductor, the elongated welded connections each extending in an irradiation direction from an irradiated area of the contact section extend at least in sections into the electrical conductor.

In particular, the device can be designed such that the position of the pressed electrical conductor is not changed between pressing and laser irradiation.

The invention also comprises a unit produced by the method according to the invention or with the device according to the invention from an electrical conductor comprising several individual wires and a contact element, the electrical conductor being arranged in a contact section of the contact element and the contact section and the electrical conductor are pressed together so that the contact section engages around the electrical conductor and there is an electrical connection between the electrical conductor and the contact element. The unit is characterized in that there are at least two elongated welded connections spaced apart from one another between the contact section and the electrical conductor, the elongated welded connections each extending in an irradiation direction from an irradiated area of the contact section into the electrical conductor at least in sections.

The invention can be used to produce a so-called B crimp form or heart crimp form, as is known from the prior art. The invention can of course also be used for other types of crimp form or compression form.

The invention makes it possible in particular to use individual wires made of aluminum or an aluminum alloy. As is known, the use of aluminum for the individual wires leads to the formation of an oxide layer on the surface of the individual wires and thus no stable resistance ratios over the service life of the conductor. However, the elongate welded connections according to the invention produce a material connection and thus electrical contact between the individual wires and the contact section of the contact element, which contact does not oxidize and therefore guarantees constant resistance ratios.

The individual wires made of aluminum or an aluminum alloy are advantageously pressed with a contact section or a contact element (for example crimp cable lug, crimp sleeve) made of copper or a copper alloy, for example bronze, brass.

The connection according to the invention can be used for high-voltage connector systems.

BRIEF DESCRIPTION OF THE FIGURES

The invention will now be explained in more detail on the basis of exemplary embodiments. The drawings are exemplary and are intended to explain the concept of the invention, but in no way restrict it or reproduce it conclusively.

Fig. 1a-d

eine erste Ausführungsvariante einer Vorrichtung zum Verpressen und Laserschweißen, für Kontaktabschnitte mit in Querrichtung unterschiedlich langen Kabelschuhkrallen,

Fig. 2

eine perspektivische Ansicht der Vorrichtung aus Fig. 1a-c,

Fig. 3a-b

die Vorrichtung aus Fig. 1a-c in Schnittdarstellung beim Laserschweißen,

Fig. 4

eine Vergrößerung aus Fig. 3b,

Fig. 5

eine Aufsicht des Kontaktelements nach dem Laserschweißen,

Fig. 6

das Kontaktelement nach dem Laserschweißen in einer Vorrichtung nach den Fig. 1a-d,

Fig. 7a-e

eine zweite Ausführungsvariante einer Vorrichtung zum Verpressen und Laserschweißen, wobei das Verpresswerkzeug eine gestufte Auflagefläche aufweist.

It shows:

Fig. 1a-d

a first variant of a device for pressing and laser welding, for contact sections with cable lug claws of different lengths in the transverse direction,

Fig. 2

a perspective view of the device Figures 1a-c ,

Figures 3a-b

the device off Figures 1a-c in sectional view during laser welding,

Fig. 4

an enlargement Figure 3b ,

Fig. 5

a top view of the contact element after laser welding,

Fig. 6

the contact element after laser welding in a device according to the Fig. 1a-d ,

Figures 7a-e

a second variant of a device for pressing and laser welding, wherein the pressing tool has a stepped support surface.

WAYS OF CARRYING OUT THE INVENTION

Fig. 1a-d show a first embodiment of a device for pressing and laser welding, these Device for contact elements is formed with contact sections with cable lug claws of different lengths in the transverse direction.

In Fig. 1a a longitudinal section through the opened device is shown. A contact element 2 (cable lug) is inserted in a lower part 1 of the pressing tool. By lowering the upper part 3 of the pressing tool, the contact section 4 of the contact element 2, which contact section 4 encompasses the electrical conductor 5, is pressed down, the ends of the cable lug claws 6, 7 being pressed inward into the conductor 5. In this way, the press or crimp connection is produced in the form of a B crimp.

In Fig. 1d the contact element 2 is shown in the state before pressing. The contact element 2 has here, seen in its longitudinal direction, a connection section 8 with a round tab for further electrical connection and a contact section 4 for pressing with the electrical conductor 5. The contact section 4 is divided into two longitudinal areas with cable lug claws 6, 7 of different lengths in the transverse direction. The shorter cable lug claw 6 then surrounds an area of the conductor 5 which is closer to the connecting section 8 and which is additionally welded with the laser. A higher degree of compression therefore results within the cable lug claw 6, for example higher than 70%, in particular higher than 80% or higher than 90%. An open rope structure of the individual wires 9 of the conductor 5 is to be ensured here. This is in Figure 1b recognizable, which is a cross section along line BB in Fig. 1a shows. Below the individual wires 9 of the conductor 5 are shown at this point, which still have a circular cross-section.

The longer cable lug claw 7 surrounds a region of the conductor 5 which is further away from the connecting section 8 and which is not welded with the laser. A lower one therefore results within the cable lug claw 7 Degree of compression, eg less than 80%. There are fewer gaps between the individual wires 9 here. This is in Figure 1c recognizable, which is a cross-section along line CC in Fig. 1a shows. At the bottom it can be seen that the individual wires 9 are pressed together so strongly that they already have a rather hexagonal cross section.

The support surface 10 (see Fig. 1a ) of the lower part 1 is straight and therefore designed the same for both cable lug claws 6.7. A laser part 11 can be lowered into the upper part 3.

Fig. 2 FIG. 4 shows a perspective view of the device from FIG Figures 1a-c , with crimped, but not yet welded conductor 5.

Figures 3a-b show the device Figures 1a-c in sectional view during laser welding, according to the representations in Figures 1a and 1b . The laser part 11 contains or is connected to a laser as a source of radiation. By means of optics containing lenses, mirrors, etc., the laser part can emit a laser beam in the irradiation direction, here the vertical, and move this laser beam horizontally along a grid, the vertical orientation of the laser beam being maintained. In this way, the laser beam can be directed to different, approximately punctiform, irradiated areas in chronological succession. The laser beams 12 are shown here as thin lines.

In Fig. 3a two laser beams 12 are shown, which each impinge in an irradiated area and form an elongated weld connection 14 downwards into the conductor 5 and up to the cable lug claw 6 on the opposite side. In Figure 3b six laser beams 12 are shown, each of which impinges in an irradiated area and forms an elongated weld connection 14 downward into the conductor 5 and up to the cable lug claw 6 on the opposite side. The elongated welded connections 14 run in the Essentially in the direction of irradiation, i.e. vertically here. They do not overlap or touch each other.

Fig. 4 shows an enlargement Figure 3b , where the elongated welded joints 14 are shown schematically and better recognizable.

Fig. 5 shows a plan view of the contact element 2 after the laser welding, where the entry points of the laser beam 12 can each be seen as the irradiated area 13. The irradiated areas 13 are regularly spaced from one another and here form a grid with rows of alternating six and five irradiated areas 13 running in the transverse direction of the contact element 2. In the longitudinal direction of the individual wires 9 or in the longitudinal direction of the contact element 2, successive rows are offset from one another in the transverse direction.

Fig. 6 shows the contact element 2 after the laser welding in the lower part 1 of the pressing tool, the irradiated areas 13 being visible here.

Figures 7a-e show a second embodiment variant of a device for pressing and laser welding, the pressing tool having a stepped support surface. Figure 7a largely corresponds Fig. 1a apart from the fact that the support surface 10 of the lower part 1 for the contact section 4 here has a different height corresponding to the two longitudinal regions of the contact section 4, thus forming two steps 15, 16. The cable lug claws 6, 7 can, but need not, be of the same length.

Figures 7d and 7e show the contact element 2 in the pressed state.

Figure 7b corresponds Figure 1b and has the same degree of compression, Figure 7c corresponds Figure 1c and has the same degree of compression.

The cable lug claw 6 surrounds an area of the conductor 5 which is closer to the connecting section 8 and which is additionally welded with the laser. Inside the cable lug claw 6 there is a step 15 further below higher degree of compression, for example higher than 70%, in particular higher than 80% or higher than 90%. Here again an open rope structure of the individual wires 9 of the conductor 5 is ensured, the individual wires 9 have as in FIG Figure 1b still has a circular cross-section.

The cable lug claw 7 again surrounds a region of the conductor 5 which is further away from the connecting section 8 and which is not welded with the laser. A lower degree of compression, for example less than 80%, therefore results within the cable lug claw 7. There are fewer gaps between the individual wires 9 here, as in FIG Figure 1c below, where the individual wires 9 are pressed together so strongly that they already have a more hexagonal cross-section.

Following the pressing takes place in the device according to the Figures 7a-c laser welding as in the Figures 3a-b and 4th instead, with the same result as in the Figures 5 and 6 .

REFERENCE LIST

1

Lower part of the pressing tool

2

Contact element (cable lug)

3

Upper part of the pressing tool

4th

Contact section

5

electrical conductor

6th

Cable lug claw

7th

Cable lug claw

8th

Connection section

9

Single wire

10

Support surface

11

Laser part (source of laser irradiation, device for laser irradiation)

12

laser beam

13

irradiated area

14th

elongated welded joint

15th

step

16

step

Claims (15)

Method for establishing an electrical connection between an electrical conductor (5) comprising several individual wires (9) and a contact element (2), the electrical conductor (5) being arranged in a contact section (4) of the contact element (2) and subsequently the contact section (4) and the electrical conductor (5) are pressed together so that the contact section (4) engages around the electrical conductor (5),
characterized in that by means of laser irradiation of the contact section (4) at least two elongated welded connections (14) spaced apart from one another are produced between the contact section (4) and the electrical conductor (5), the elongated welded connections (14) each extending in an irradiation direction from an irradiated area (13) of the contact section (4) extend at least in sections into the electrical conductor (5). Method according to Claim 1, characterized in that the laser irradiation is carried out in such a way that the elongate welded connection (14) extends in the direction of irradiation through the entire cross section of the pressed electrical conductor (5). Method according to one of Claims 1 to 2, characterized in that several elongated welded connections (14) are produced one after the other by the same source (11) of the laser irradiation. Method according to one of the preceding claims, characterized in that several elongated Welded connections (14) are produced in irradiated areas (13) which are regularly spaced from one another. Method according to one of the preceding claims, characterized in that one irradiated area (13) is offset from another irradiated area (13) normal to the longitudinal direction of the individual wires (9). Method according to one of the preceding claims, characterized in that the degree of compression of the individual wires (9) in a longitudinal area of the contact element (2) in which there are no irradiated areas is lower than in a longitudinal area of the contact element (2) where irradiated Areas (13) are located. Method according to Claim 6, characterized in that the different degree of compression is produced by a compression tool (1) with a stepped support surface (10, 15, 16). Method according to Claim 6 or 7, characterized in that the different degrees of compression are produced by a contact section (4) with cable lug claws (6, 7) of different lengths in the transverse direction. Method according to one of the preceding claims, characterized in that the degree of compression of the individual wires (9) in a longitudinal region of the contact element where irradiated regions (13) are located is greater than 70%. Method according to one of the preceding claims, characterized in that the laser irradiation takes place in that tool (1,3) in which the pressing takes place. Method according to Claim 10, characterized in that the position of the pressed electrical conductor (5) is not changed between pressing and laser irradiation. Method according to one of the preceding claims, characterized in that the production of an elongate welded connection (14) takes less than 50 ms, in particular less than 40 ms, for example around 30 ms. Method according to one of the preceding claims, characterized in that the contact section (4) is provided with a nickel coating at least in the area where it touches the electrical conductor (5). Device for establishing an electrical connection between an electrical conductor (5) comprising several individual wires (9) and a contact element (2), the device comprising a pressing tool (1,3) with which the in a contact section (4) of the contact element (2 ) arranged electrical conductor (5) can be pressed with the contact element (2) so that the contact section (4) engages around the electrical conductor (5),
characterized in that a device (11) for laser irradiation is provided which is designed to produce at least two elongated welded connections (14) spaced apart from one another between the contact section (4) and the electrical conductor (5), the elongated welded connections (14) extend in an irradiation direction from an irradiated region (13) of the contact section (4) at least in sections into the electrical conductor (5). Unit of an electrical conductor (5) comprising several individual wires (9) and a contact element (2), wherein the electrical conductor (5) is arranged in a contact section (4) of the contact element (2) and the contact section (4) and the electrical conductor (5) are pressed together so that the contact section (4) engages around the electrical conductor (5) and there is an electrical connection between the electrical conductor (5) and the contact element (2), characterized in that there are at least two elongated welded connections (14) spaced apart from one another between the contact section (4) and the electrical conductor (5), the elongated welded connections (14) each extend in an irradiation direction from an irradiated area (13) of the contact section (4) at least in sections into the electrical conductor (5).

Images