A process for the production of an electrically conducting and mechanically solid connection between armature coil wires and hooks on the lamellas of a commutator comprising 1) laying the insulated wires around the hooks of the lamellas without stripping the insulation; 2) before bending back the hooks, at least partially destroying by thermal and/or mechanical abrading means, the varnish insulating on the wires; 3) removing the residues or remnants of the varnish insulation layer during the bending back of the hooks, by ultrasonic oscillations; 4) squeezing the removed varnish into a wedge-shaped space formed between the winding wire, the internal surface of the hook and the surface of the commutator; and 5) ultrasonically welding the hook ends to the lamellas. Variously constructed devices for the execution of the process are also proposed.