Flexible Twisting Process of Stators with Hairpin Winding

Abstract

In recent years, the hairpin technology has become the most relevant process chain for manufacturing of stator windings applied in electric traction motors. However, there are still limitations with regard to flexibility and the economic production of small quantities - especially due to the tool-bound process steps. Resulting from the complex machine kinematics and a stator-specific tooling for the simultaneous forming of several hundred open coil endings, the twisting process of the subsequently welded winding head of hairpin stators is critical in particular. Against this background, a robot-based approach for a flexible twisting process is presented in this paper as an alternative to conventionally used machine configurations. In this way, both an economical small series production of stators and accelerated prototyping should be enabled. In the beginning, this paper covers the general process sequence as well as the developed machine and tooling concept. To compensate the increased effort for start-up and control required for sequential kinematic wire forming, the basic framework of a dedicated simulation environment for rapid offline planning is introduced. Finally, the prototype of the developed machine set-up is presented and additionally used for an experimental proof of concept.