Investigation of the Influence Parameters on the Joining Force of the Hairpin Coil Insertion Process

In the context of electric traction motor production, the hairpin technology has recently established itself as the predominant winding technology for stators. In addition to product-side advantages, the production can be designed in a modular way, as it is characterized by individual successive process steps. However, there can be many interdependencies between these process steps that have a significant impact on the quality of the final product. One of these process steps is the insertion of hairpin coils into the lamination stack, during which high joining forces as well as deformation or damage to the conductors or the winding head can occur. In order to identify possible influences on the forces during the insertion process, a theoretical influence analysis is carried out. This is followed by experimental investigations using tensile and compression testing machines. These include an examination of the influences of the slot liner material and the conductor insulation material as well as hairpin coil deformations resulting from the previous bending or handling process.