Ultrasonic welding apparatus and method

A method for welding a connecting part with a stranded conductor using an ultrasonic welding device having a sonotrode and a counterbearing opposite the sonotrode, wherein the counterbearing is movably mounted parallel to a direction of oscillation of the sonotrode, and wherein the counterbearing is mounted dynamically such that it is periodically elongated by the oscillation energy coupled in by the activated sonotrode, comprising:

• fastening the connecting part to the counterbearing;
• placing the stranded wire on the connecting part;
• pressing the sonotrode onto the stranded conductor;
• and
• introducing, from the sonotrode, an ultrasonic oscillation perpendicular to the surface normal of the connecting part into the stranded conductor, the counterbearing oscillating relative to the sonotrode in a direction of oscillation parallel to the direction of oscillation of the sonotrode.