Process for reducing aluminium pick-up, and ultrasonic welding device
A process for reducing aluminum pick-up and adherence during the ultrasonic welding of aluminum braids which are welded in a vertically and/or horizontally adjustable compression chamber of an ultrasonic welding device. The static tool parts which delimit the compression chamber have working surfaces made from polycrystalline diamond (PCD).
1. Process for the reduction of pick-up and/or adhesion of aluminum or aluminum alloy during ultrasonic welding of strands comprising leads or single wires of aluminum or aluminum alloy, to an end- or intermediate node, to one another, or to a carrier made of metal, wherein:
at least the aluminum or aluminum alloy strands are inserted into a vertically and/or width-wise adjustable compression chamber, which is delimited in facing first boundary surfaces by sections of a sonotrode and an anvil or a carrier that is disposed on the anvil, and in remaining facing second boundary surfaces by statically acting tool parts,
wherein the static tool parts each comprise a work surface;
wherein among the first and second boundary surfaces polycrystalline diamond is present only on each work surface of the static tool parts.
2. Process according to claim 1 , characterized in that, besides the strands comprising leads or single wires of aluminum or aluminum alloys, second strands made from another material are welded together.
3. Process according to claim 1 , characterized in that the polycrystalline diamond is an upper layer of a metal carrier which is attached to the static tool part.
4. Process according to claim 3 , characterized in that that the polycrystalline diamond forms a layer of a thickness (d) with (d)≧0.1 mm, on the metal carrier having a thickness (D) of 0.8 mm≦(D)≦2.0 mm.
5. Process according to claim 3 , characterized in that the polycrystalline diamond forms a layer having a thickness that prevents the trans-diffusion of aluminum.
6. Process according to claim 4 , characterized in that the layer made from polycrystalline diamond comprises diamond kernels between 90 volume % and 95 volume %.
7. Process according to claim 1 , wherein the polycrystalline diamond is hard soldered to the static tool parts.
8. Process according to claim 4 , wherein the thickness (d) is 0.2 mm≦(d)≦0.7 mm.
9. Process according to claim 1 , characterized in that that the polycrystalline diamond forms a layer of a thickness (d) of 0.2 mm≦(d)≦0.7 mm.
10. Process according to claim 1 , wherein the strands are inserted without an intermediate foil between the static tool parts and the strands.