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Energy technology is an important research area in terms of sustainability. Products manufactured by forming technology also play a decisive role in this.
The production of electrical steel sheet and coil windings for electric motors, for example, have a major influence on their efficiency.
But also in the field of turbomachinery and wind turbines, large metallic components contribute significantly to their function and efficiency.
The research topics embedded in this cross-sectional area are assigned to different research groups and are presented below.
Cold Rolling Strategies for Producing Magnetic-Optimized Electrical Steel Sheet in Energy-Efficient Electrical Drives
One way to increase the efficiency of electric drives is to optimize the magnetic properties of the electrical steel used in the magnetic core. In order to quantify the influence of process parameters on these final properties and to create a scientific-theoretical basis for the development of low-loss electrical steel, an interdisciplinary DFG research group, FOR 1897, is working on the integrated process chain modeling. The main task of the IBF is to investigate and simulate the cold rolling process. Experimentally, the IBF will test different rolling strategies on the cold and hot rolling mill. A multi-scale model that includes a macroscopic finite element model and a microscopic crystal plasticity finite element model is created to compute the texture evolution, which makes it possible to determine the influence of different rolling strategies and initial states on the local texture development during cold rolling. By linking the sub-models, it enables model-based process design of low-loss electrical sheets for highly efficient electric drives.
For further information, please contact Johannes Lohmar.
Image: Multi-scale model for simulating texture evolution during cold rolling, Copyright: IBF, IMM
Specific Shaped Copper Windings Manufactured by Forming Technique
The electrical wheel hub motor is a promising technology for the development of future urban mobility. Specific shaped copper windings with a rectangular cross section offer the potential of a better exploitation of the available coil assembly space, causing a higher power density of the electric motor. At the institute of metal forming, briefly IBF, the production of these specific shaped copper windings using forming technology is investigated. Thereto, different manufacturing approaches were developed. The advantages and disadvantages of these manufacturing approaches are examined practically. The main objective of the project is a good efficiency of the manufacturing chain, so that an economic benefit of a production with high quantaties is ensured.
For further information, please contact Daniel Petrell.
Image: CAD construction of specific shaped copper windings, Copyright: IBF
Simulation of the Process Chain for a Turbine Disc
The production of turbine discs for aerospace applications is characterized by very strict safety requirements including tight windows for the microstructure. The evolution of the microstructure therefor needs to be accounted for during the design of the process chain. Accordingly an online-coupling between StrucSim, a program calculating the microstructure, and the commercial finite element, short FE, Software Simufact was developed. This means that StrucSim is called during the FE Simulation and influencing its results. Subsequently the process chain was reproduced in FE Simulations and calculated using the online-coupling. Thereby the microstructure evolution was calculated for the whole workpiece along the process chain. This technique can be used to optimize processes or process chains regarding productivity or reproducibility in the future.
For further information, please contact Jannik Gerlach.
Image: Turbine disc process chain and position in the engine, Copyright: Leistritz, SMS, IBF
Profile Ring Rolling
Profiling of ring rolled components is an important step for the near net shape production, which leads to material savings as well as time saving regarding the machining. Based on the area of application, all four sides of the cross section can be profiled. Dependent on the type of the profile and the geometry of the ring different challenges during the process occur. Examples for these challenges are the reaching of the desired profile filling and conicity in the cross section.
For further information, please contact Stefan Günther.
Image: Axial roll gap during the axial profiling process, Copyright: IBF
Open-Die Forging of Hollow Shafts
During the last years, the importance of alternative energy sources as wind energy has risen constantly. A higher energy production by wind power plants cannot only be achieved by setting up additional wind parks, but also by an increase in the performance and by this the size of newly built plants. The electric capacity of up to 6 MW requires larger generators which transform the mechanical to electrical energy. This leads to an increased weight of the whole tower construction. One possible approach to realize lightweight construction is to replace the commonly casted hollow generator shaft by a forged shaft with significantly better mechanical properties. Compared to casted hollow shaft, a weight reduction of 50-60% can be realized. For this purpose, the IBF has successfully developed a forging method performed on the open-die forging center, which allows the open-die forging of hollow shafts with an outer and inner contour with respect to an optimized microstructure to ensure good mechanical properties.
For further information, please contact Niklas Reinisch.
Image: Open-die forging of an inner-contoured hollow shaft at IBF, Copyright: IBF
FE Simulation of Multi-Stage Bending Processes
The stamping and bending technology is used for the production of complex bending parts, for example for the electric industry. The process design is mainly based on expert knowledge and experimental testing. Aim of the cooperation project with Phoenix Feinbau GmbH & Co. KG is the development of precise FE models to describe multi-stage bending processes and the springback behavior of the produced parts. One key aspect is the identification of material data of high-strength spring steels by means of an inverse modeling approach under bending conditions. Experimental investigations are further carried out to implement the FE boundary conditions correctly. The validated FE models are then applied to examine and evaluate different influencing factors on the final parts in stamping and bending processes.
For further information, please contact Thomas Bremen.
Image: Bending center of a stamping and bending machine, Copyright: Phoenix Feinbau GmbH & Co. KG