M. Spahr

Explicit dynamics process simulation of linear coil winding for electric drives production

Slowly but steadily, more and more electric vehicles push onto the consumer market. For a cost efficient production of electrical engines, in first-class quality and in sufficient quantity, it is indispensable to understand the process of coil winding. Thereby the prediction of the wire behavior is one of the key challenges. Therefore, a detailed model is built to investigate wire behavior during the linear winding process. The finite element based simulation tool LS-DYNA serves as explicit dynamics tool. To represent the high dynamic process of winding within this simulation, some first adaptions have to be made. This means, that dynamic influences such as rotational speed or acceleration of the coil body are definable. Within process simulation, the given boundary conditions are applied to the model. The material properties of the wire under scrutiny are validated by a tensile test and by the values out of datasheets in previous research. In order to achieve the best convergence, different contact algorithms are selected for each individual contact behavior. Furthermore, specific adjustments to the mesh are necessary to gain significant results. State of the art in coil winding is an experimental procedure, which delivers adequate process parameters and, thus, expertise in winding technology. Nevertheless, there are a lot of different, interacting parameters, which have to be optimized in terms of boundary conditions. The simulation model of winding process, in which varying parameters can be optimized pertaining to the optimal winding result, calls for extensive research in this field. The generated model enables the user not only to influence the process parameters but also to modify the geometry of a winding body. To make the simulation scientifically sound, it is validated by previous experiments and simulations

Simulation of orthocyclic windings using the linear winding technique

A continuously rising number of electric vehicle licensing is mentioned since the last few years in Germany. For a cost-efficient production of electrical engines in first-class quality and in sufficient quantity, it is indispensable to understand the process of coil winding. Thereby, the prediction of wire behavior is one of the key challenges. Therefore, a detailed model is built to investigate wire behavior during the linear winding process. The finite element based simulation tool LS-DYNA serves as explicit dynamics tool. The tool works with an explicit time integration method for time discretization. To represent the high dynamic process of winding within this simulation, dynamic influences such as rotational speed or acceleration of the coil body are definable. Within process simulation, the given boundary conditions are applied to the model. The non-linear material properties of the wire are validated under scrutiny by a tensile test and by values out of datasheets in previous research work. Simulation results of orthocyclic windings using the linear winding technique are presented within this paper. The dynamic simulation model is validated by experiments using the caster angle of the wire guide as reference parameter. The caster angel rises during the winding process of the first layer until the wire jumps to the next layer. Hence, it is possible to identify the maximum caster angle and match the simulation value against the experiment value. The travel profile of the wire guide is identified as extremely important to generate an orthocyclic winding. Another substantial part is the wire fixation respectively the geometry to support the first winding offset from winding one to winding two. Results of orthocyclic windings are simulated with and without grooves on the coil body surface and demonstrate the positive influence of grooves for an accurate orthocyclic winding picture.

The Least Energy Demand Method as unique tool to evaluate and rate the energy efficiency of the electric drives production

This paper evaluates a method for the assessment and evaluation of energy efficiency of the manufacturing process in the electric drive production as well as a corporate and cross-industry comparison. First, the system for the Least Energy Demand Method will be explained. The basic idea of the calculation is the comparison and evaluation of energy efficiency based on the ratio of the theoretically required energy consumption to the measured energy consumption [8]. The Least Energy Demand Method is subsequently extended with the calculation system to evaluate the relative energy efficiency (REE) of higher levels of perspective. The goal is a comparability of the energy efficiency across machines, plants, locations, companies and sectors through definition of significant key figures. The basis of the derivation of possible saving potentials is the relative energy efficiency [6]. The REE of a level of perspective is calculated on the basis of the REE value of the previous production level as well as according to weighting factors. On the basis of the calculation, as well as subsequent measurements within the company, optimization potentials [10] can be clearly described and traced back to their roots. These optimization potentials are based on exemplary trials presented for a chosen manufacturing chain of an electronic production area [5]. The system of the energy efficiency evaluation during the manufacturing process is applied in the production of stators for bike motors.

Innovative Kontaktierungstechnologien im Elektromaschinenbau

Kurzfassung Im sich dynamisch entwickelnden Feld der elektrischen Antriebstechnik stellen neue, von der Automobilindustrie getriebene Motortopologien sowie die Forderung nach serienflexiblen Prozessen die zentralen Treiber zur Entwicklung innovativer Kontaktierungsverfahren dar. Die Arbeitsgruppe Kontaktierungstechnologien begegnet diesem Spannungsfeld mit einem multidimensionalen Ansatz, der aus der Weiterentwicklung bestehender und aus der Erforschung neuartiger Kontaktierungslösungen besteht.

Explicit finite element analysis for rotary cutting of electrical steel sheet

Rotary cutting of rotor and stator laminations complements the available methods in the processing of electrical steel sheet. Furthermore, with this process, a technological answer to the production of ever-thinner laminations can be found in which high-speed stamping is reaching its technical limits. This paper explicates a finite element analysis for the rotary cutting process of electrical steel. First an overview of the cutting process and its peculiarities is given. Then the setup for the FEM simulation and its material model are explained. Finally followed by a discussion of simulation results with different parameters.

Energy Planning of Manufacturing Systems with Methods-Energy Measurement (MEM) and Multi-Domain Simulation Approach

Energy costs play a decisive role in the operation costs of automotive production companies. Therefore, energy planning in an early conception and planning stage becomes an important topic. This is because the early conception and planning stage has the greatest potential to influence the energy consumption of manufacturing technologies since about 70-80 % of the energy costs are committed during this stage. However, lifetime cost and specifically energy consumption are currently not a determining factor at this stage. The reason is that the prediction of energy costs for complex manufacturing systems are challenging. Previous research approaches in the area of energy planning are limited to detailed planned production. A standardized approach to determine the energy consumption rates at an early stage does not exist. In this context, the EffiPLAS project has therefore proposed to solve this challenge. The aim of this project is to develop a Methods-Energy Measurement approach with elementary energy elements to support the planning process at an early stage, and to develop a modular simulation model for calculating the energy consumption of industrial robots, which complements the energy prediction. In this paper, the basic concept of elementary energy units and their value determination techniques is presented, and the simulation model is outlined. The developed approach will help to predict the prospective energy consumption of complex production equipment so that energy costs can be accounted for in an improved manner within a life-cycle costing comparative analyses.