Joining a terminal element with a stranded conductor

Abstract

A connection of a strand conductor to a connecting part, via an end of the strand conductor and a connecting part materially connected to the end of the strand conductor, wherein one end face of the end of the strand conductor is welded to the connecting part by means of ultrasound. A particularly good weld seam is achieved by first welding the end of the strand conductor to a sleeve using ultrasonic welding.

Claims

1. A method for producing a connection between a stranded conductor and a connecting part, comprising: enclosing an end of the stranded conductor by a sleeve, and connecting the connecting part in a material-locking manner to the end of the stranded conductor, wherein an end face of the end of the stranded conductor is welded to the connecting part by ultrasonic welding, prior to the ultrasonic welding of the end face of the stranded conductor to the connecting part, the stranded conductor is ultrasonic welded to the sleeve, the strands of the stranded conductor are materially-locked together, and an outside surface of the stranded conductor is materially-locked to an inside surface of the sleeve.

2. The method according to claim 1, wherein the end face of the end of the stranded conductor is welded to the connecting part by ultrasonic roll welding or by longitudinal ultrasonic welding.

3. The method according to claim 1, wherein the stranded conductor is formed from an aluminium material or a copper material.

4. The method according to claim 1, wherein the connecting part is a flat part.

5. The method according to claim 1, wherein the strands are pressed into a bundle by the sleeve.

6. The method according to claim 5, wherein the sleeve absorbs upsetting forces of an ultrasonic welding tool.

7. The method according to claim 1, wherein a cavity free weld seam is formed between the end face of the end of the strand conductor together with the sleeve and the connecting part.

8. The method according to claim 1, wherein the sleeve is formed from an aluminium material or a copper material.

9. The method according to claim 1, wherein the connecting part is a flat conductor or a sheet-metal stamped part, and wherein one end of the flat conductor or sheet-metal stamped part is connected to the stranded conductor.

10. The method according to claim 1, wherein the connecting part is a round conductor.

11. A connection of a stranded conductor and a connecting part, comprising: a sleeve enclosing an end of the stranded conductor, and the connecting part which is connected in a material-locking manner to the end of the stranded conductor, wherein an ultrasonic welding seam is formed between an end face of the end of the stranded conductor and the connecting part, an ultrasonic welding seam is formed between the stranded conductor and the sleeve, the strands of the stranded conductor are materially-locked together, and an outside surface of the stranded conductor is materially-locked to an inside surface of the sleeve.

12. The method of claim 1, wherein the connecting part is formed from an aluminium material or a copper material.

13. The method of claim 1, wherein the connecting part is formed from a composite material.

14. The method of claim 13, wherein the connecting part is formed from a plastic-aluminium composite material.

Description

BRIEF DESCRIPTIONS OF THE DRAWINGS

(1) FIG. 1A shows a first possible welded connection of a stranded conductor with a flat conductor;

(2) FIG. 1B shows a device for the first possible welded connection;

(3) FIG. 2A shows a second possible welded connection of a stranded conductor with a flat conductor;

(4) FIG. 2A shows a device for the second possible welded connection;

(5) FIG. 3A shows a third possible welded connection of a stranded conductor with a flat conductor;

(6) FIG. 3B shows a device for the third possible welded connection;

(7) FIG. 4 shows a schematic representation of ultrasonic roll welding; and

(8) FIG. 5 shows a flow chart of a process according to an embodiment.

(9) FIG. 1A shows a stranded conductor 2 (which can also be a stamped sheet metal part), for example an aluminium stranded conductor, which is referred to below as a representative, with a stripped end 4. The stripped end 4 shows the aluminium strands 6. The aluminium strand conductor 2 shown in FIG. 1A is pressed at its stripped end 4 by means of a sleeve 8 in such a way that the aluminium strands 6 are compacted so that between the aluminium strands 6 air inclusions are essentially removed. The inner surface of the sleeve 8 is then ultrasonically welded to the aluminium strands so that a material-locking connection is formed between the sleeve 8 and the aluminium strands 6.

(10) The end face of the aluminium strand conductor 2, which is compacted in this way and connected to the sleeve in a material-locking manner, is freed of aluminium oxide, for example, by means of a machining process. A laser decoating can also be used.

(11) Immediately afterwards, the stripped end 4 together with sleeve 8 is ultrasonically welded to a connecting part 10.

(12) FIG. 1B shows a structure of a system for making a connection as shown in FIG. 1A.

(13) The stripped end 4 of the stranded wire 2 is first clamped by two gripper arms 12. The gripper arms 12 could be press punches, which can press the sleeve positively with the stranded conductor. Either the stripped end 4 can be pressed alone or together with a sleeve 8. This results in a compacted end of the strands 6. After compaction, the gripper arms can weld the sleeve 8 to the strands 6 of the cable 2 as ultrasonic welding surfaces by means of ultrasonic welding. A material bond (material locking) is formed between the strands 6 and the inner surface of the sleeve 8.

(14) The gripper arms 12 can then lead the sleeve 8 together with cable 2 to the connection part 10 formed here as a cable lug.

(15) There a horn 14 can be guided in the direction of the longitudinal axis of cable 2 onto the contact surface between cable 2 and connection part 10. The grippers 12 form the counterforce to the contact pressure applied axially by the horn 14. The horn 14 can use ultrasonic welding, longitudinal or rolling, to introduce welding energy into the connection point between the connecting part 10 and the strands 6 and the sleeve 8 to create a material-locking connection between the connecting part 10 and the strands 6 and the sleeve 8.

(16) FIG. 2A shows a configuration similar to FIG. 1A. After compacting and/or welding between the strands 6 and the sleeve 8, an angled end face was first produced on the face side using a machining process. A connection part 10, here e.g. a flat conductor, can be welded to this end face at an angle to the longitudinal axis using ultrasonic welding. By welding between the sleeve 8 and the strands 6 on the inside of the sleeve 8, it is achieved that the strand 6 is pressed out of the sleeve 8 during the subsequent forming of the end face or welding with the connecting part 10.

(17) FIG. 2B shows a structure of a system for making a connection as shown in FIG. 2A.

(18) The stripped end 4 of the stranded wire 2 is first clamped by two gripper arms 12. Either the stripped end 4 can be pressed alone or together with a sleeve 8. This results in a compacted end of the strands 6. After compaction, the gripper arms can weld the sleeve 8 on its sheath to the strands 6 of the cable 2 as ultrasonic welding surfaces by means of ultrasonic welding. A material bond is formed between the strands 6 and the inner surface of the sleeve 8.

(19) The gripper arms 12 can then first guide the sleeve 8 together with cable 2 up to a milling device on which the end face is milled flat at an angle to the longitudinal axis of cable 2. Any protruding strand ends and parts of the sleeve are removed. Cutting is also possible.

(20) The gripper arms 12 can then guide the sleeve 8 together with cable 2 to the connection part 10 formed here as a cable lug.

(21) Here, a horn 14 can be brought up to the contact surface between cable 2 and connection part 10 at an angle to the longitudinal axis of cable 2. The grippers 12 form the counterforce to the contact pressure applied axially by the horn 14. The horn 14 can use ultrasonic welding, longitudinal or rolling, to introduce welding energy into the connection point between the connecting part 10 and the strands 6 and the sleeve 8 to create a material-locking connection between the connecting part 10 and the strands 6 and the sleeve 8.

(22) FIG. 3A shows a configuration of the gripper arms 12 for compacting and simultaneously welding strands 6 and sleeve 8, whereby a cross-section through sleeve 8 together with cable 2 with the gripper arms 12 is also shown.

(23) A first gripper arm 12a can be formed as a horn and a second gripper arm 12b can be formed as an anvil.

(24) First the gripper arms 12a, 12b are moved towards the sleeve 8 with the strands 6 as shown in the section and the sleeve 8 is pressed in such a way that the strands 6 are compacted in it.

(25) The aluminium sleeve 8, for example, can have a wall thickness of less than 2 mm. The aluminium sleeve 8 can also be shorter than 5 cm, for example, and preferably shorter than 3 cm.

(26) The sleeve 8 is then welded to the strands 6 on its inner surface by means of longitudinal ultrasonic welding, so that a material-locking connection is formed there.

(27) As shown in FIG. 3B, this connection is welded to the connecting part by the horn 14. For this purpose, the horn 14 is pressed against the connection part 10 and then the ultrasonic welding process is carried out. This creates a material-locking connection between the connecting part 10 and the strands 6 as well as the sleeve 8.

(28) For welding, either longitudinal welding or roll welding can be used.

(29) Ultrasonic roll welding enables joining partners to be welded together with short cycle times, for example with a welding time of 1.5 seconds or less, for example 1.2 seconds. The axial end position of the parts to be joined is permanently defined during ultrasonic roll welding.

(30) FIG. 4 shows a sectional view through a horn 14. The horn 14 is mounted so that it can rotate about its longitudinal axis 14a. A working surface 16 is provided on a circumferential surface of horn 14. The entire working surface 16 has a radial distance R from the longitudinal axis 14a. The horn 14 is preferably axially symmetrical to at least the symmetry axis 18, which runs perpendicular to the longitudinal axis 14a and preferably perpendicular to the working surface 16.

(31) The horn 14 is rotated along direction 20 during roll welding, whereby the frequency of the oscillation is preferably at least 20 kHz. During this time the horn 12 is pressed in direction 22 against a workpiece to be welded.

(32) FIG. 5 shows schematically a flow chart of a method according to the subject matter. In a first step 30, an endless aluminium strip can be unwound from a coil and fed to a splicing crimping tool. For this purpose, the aluminium strip is cut in a single operation, formed around the strands 6 of the aluminium strand conductor 2 and pressed. This compacts the aluminium strands 6 of the aluminium strand conductor 2 and prevents cavities. This can be done in one step 32. In a step 34, the stripped end, which is pressed with the pressed part, is led with a sheet metal bending part to a horn 12 and the horn 12 presses the sheet metal bending part 10 against the end face of the aluminium strand conductor 6 and the pressed part 8. In a step 38, a rolling movement is applied to the sheet metal bending part 10 by means of the horn 12. Welding energy is thus transferred to the sheet metal bent part 10 and the aluminium strand conductor 6.