Calculation of Process Parameters for the Twisting of Stators with Hairpin Winding

In recent years, the so-called hairpin technology has become widely accepted for the manufacturing of high-quality distributed stator windings used in automotive traction motors due to its advantageous productivity compared to other winding technologies. However, the time-consuming and resource-intensive ramp-up of the key processes of hairpin coil bending, assembly and joining, as well as widening and twisting of the open coil endings remains a major challenge. Although the machine and equipment manufacturing industry has already installed many series production lines for stators with hairpin winding within the last few years, the process parameters for twisting and widening, which are mainly based on the stator design and the rectangular wire forming properties, are often still determined by extensive experimental test series. In addition, a scientific approach for calculating the necessary tool motions to speed up the process commissioning has not been published in detail yet. Against this background, a generalized geometric wire model for the calculation of tool motions for the twisting process of stators with hairpin winding is presented in this paper and validated with both finite element simulations and experimental results.