Two workpieces 30, 40 are joined by means of ultrasound. First, a workpiece 30 with at least one energy direction sensor 31 and a second workpiece 40 are provided. The workpieces are brought into contact with each other in such a way that the energy direction sensor 31 comes into contact with a first surface 41 of the second workpiece 40. Ultrasonic vibrations are then introduced into one of the workpieces 40 via a working surface 11 of a sonotrode 10. A sonotrode 10 is used, which has a contour with contact lines 12 on the working surface 11. The sonotrode 10 is positioned with respect to the first workpiece 30 in such a way that the contact lines 12 run transversely to the energy direction generator 31.

The present invention relates to a method for evaluating an assembly by welding of parts made of thermoplastic materials, to a test piece and its associated uses, to an installation for implementing this method and to the associated welding system.

A method for welding at least two parts including a thermoplastic material and having respective surfaces to be welded, including: inserting an insert between the surfaces to be welded of the two parts; generating heat via the insert; wherein the insert moves in relation to the parts to be welded in a welding direction. Also, an installation adapted for implementation of this method.

The invention first relates to a method for welding at least two parts comprising a thermoplastic material and having respective surfaces to be welded, comprising: inserting an insert between the surfaces to be welded of the two parts; generating heat via said insert; wherein the insert moves in relation to the parts to be welded in a welding direction. The invention also relates to an installation adapted for implementation of this method.

A test piece configured for the implementation of a method for evaluating an assembly by welding of parts made of thermoplastic materials, wherein the test piece includes at least two parts based on thermoplastic materials having surfaces to be welded that are at least partially placed opposite one another and respective free surfaces, wherein at least one of the parts is a perforated reference part including at least one perforation.