Optimization of the Linear Coil Winding Process by Combining New Actuator Principles on the Basis of Wire Forming Analysis

Abstract

Due to the electrification of the automotive drive train new challenges in production technology must be faced. One of the big challenges are the copper losses within the electric drive that can be reduced by an optimized layer structure of the winding on the coil. This paper is targeting an optimized linear coil winding process with a special focus on the first layer which is decisive for the quality of the following layers. Here, the forming influence of the wire during winding on the bobbin is examined in particular. Crucial parameters in this context are the change in diameter through bending and the development of the clearance between wire and coil bobbin including their main influencing parameters. Especially the wire guide represents a machine element which influences the clearance negatively. This paper focuses on deriving critical process points from a process model and deriving forming strategies for controlling the winding process. For the first time, two actuator principles are combined to compensate the fluctuations in wire tensile force during winding and also to minimize the influence of the wire guide by moving it according to a FE simulation. Therefore, firstly the state of the art is analyzed and characterized in order to derive systematically the selection of the actuators and the control strategy. This is done in the context of achieving a higher efficiency of the electric motor through a deeper understanding of the forming process. On the one hand the integration of a fluidic muscle is serving as a compensation of the free wire length between the wire guide and the coil bobbin for a normalization of the wire tensile force. On the other hand, a piezo actuator is preventing the pre-deformation of the wire by the wire guide for keeping the clearance at a low level.