Method for connecting an aluminum electrical wire with an aluminum tube

Abstract

A method for connecting an electrical cable having at least one wire made of aluminum or an aluminum alloy to a connector element includes the following steps: Inserting a stripped portion at an end of the electrical cable into a tube of the connector element. Crimping the tube where an end portion of the electrical cable is arranged so that a relative motion between the tube and the electrical cable is prevented. Crimping the tube where a second portion of the electrical cable is arranged, the second portion being further from the end of the electrical cable than the end portion, such that a change of the cross section and an elongation of the least one wire at the second portion of the electrical cable is caused. Resistance welding the tube to the at least one wire at the second portion of the electrical cable.

Claims

1. A method, comprising: inserting a stripped portion at an end of an electrical cable having at least one wire made of aluminum or an aluminum alloy into a tube of a connector element made of aluminum or the aluminum alloy; arranging an end portion of the electrical cable in a first area of the tube; arranging a second portion of the electrical cable in a second area of the tube, the second portion being further from the end of the electrical cable than the end portion; crimping the tube in the first area such that a relative motion between the tube and the at least one wire of the electrical cable is prevented; crimping the tube in the second area and causing an elongation of the least one wire at the second portion of the electrical cable; and resistance welding the tube to the at least one wire at the second portion of the electrical cable.

2. The method as in claim 1, further comprising: providing a first crimping tool; and providing a second crimping tool with two welding electrodes, wherein crimping the tube in the first area is effected by the first crimping tool and wherein crimping the tube in the second area effected by the two welding electrodes.

3. The method as in claim 1, wherein crimping the tube in the second area and resistance welding the tube to the at least one wire are simultaneous.

4. The method as in claim 1, wherein crimping the tube in the first area includes crimping the tube in the first area with a compression tool.

5. The method as in claim 4, wherein crimping the tube in the first area with the compression tool comprises causing at least two parts of the compression tool to completely surround the tube.

6. The method as in claim 4, further comprising: keeping the compression tool closed while crimping the tube in the second area and opening the compression tool only after resistance welding the tube to the at least one wire.

7. The method as in claim 1, further comprising: providing a first crimping tool; and providing a second crimping tool, wherein crimping the tube in the first area is effected by the first crimping tool and wherein crimping the tube in the second area comprises axially moving the second crimping tool along the at least one wire away from the end portion of the electrical cable.

8. The method as in claim 1, further comprising: causing an oxide layer on the at least one wire to break.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The method is further explained by reference to three drawings:

(2) FIG. 1 shows an electrical cable with a connector element before crimping and welding.

(3) FIG. 2 shows the electrical cable with the connector element after having been crimped and welded.

(4) FIG. 3 shows a compression tool in combination with the electrical cable as in FIG. 2.

DETAILED DESCRIPTION

(5) Referring to FIG. 1, an electrical cable 1 includes a stranded aluminum wire 2 which is surrounded by an insulation 3. The individual strands of the stranded aluminum wire 2 are illustrated. A tube 4 is shown having a first open end 5 into which the stranded aluminum wire 2 of a stripped end of the electrical cable 1 has been inserted. A connector element 7 is formed at a second end 6 of the tube 4.

(6) Referring to FIG. 2, the electrical cable 1 is shown with the connector element 7 after the crimping and welding process has been completed. A first crimped area 9 is shown in an end region 8 of the stranded aluminum wire 2. At the first crimped area 9 the stranded aluminum wire 2 has been compressed by the tube 4 such that the individual strands of the stranded aluminum wire 2 can no longer move relative to one another. Adjacent to the first crimped area 9 a second crimped area 10 is shown in direction towards the insulation 3. The stranded aluminum wire 2 has been compressed and elongated in the second crimped area 10 due to its strands being unable to move relative to each other at the first crimped area 9 and in the area covered by the insulation 3. This has caused the oxide layer on almost all strands of the stranded aluminum wire 2 to break. By crimping also the oxide layer on the inside of the tube 4 has been broken.

(7) By a subsequent welding process the stranded aluminum wire 2 has been welded over a large area to the pipe 4 as illustrated by the weld nugget 11.

(8) FIG. 3 shows a compression tool 12 to perform the first crimping. The compression tool 12 comprises two parts that completely surround the tube during the crimping operation. The second crimping operation is performed by two welding electrodes 13, 14. A separate compression tool for the second crimping step is not necessary, and the welding electrodes can cost effectively be used to perform the second compression step, functioning as a second compression tool.