 | 2008 |
Abstract:
Lightweight frame structures made of aluminum extrusions and load optimized connecting elements allow the reduction of weight and energy consumption as well as the increase of payload in automotive engineering. New, continuously reinforced aluminum profiles and load optimized connecting elements require the use of adapted manufacturing technologies e. g. circular milling and simultaneous five axis milling) in order to achieve a high-quality product. Complex constructions and manufacturing processes can nowadays be designed and optimized with the help of modern simulation technologies. Especially the flexible machining of single or limited products on the basis of common machining strategies is still inefficient and economically unacceptable. The use of reinforced aluminum profiles can increase the tensile strength of a frame structure and reduce the growth of cracks, but hard reinforcing materials have a strong influence on wear of a cutting tool and the surface quality of functional elements or threads. During the machining process the thermo-mechanical load influences the peripheral zone and contact zone of a workpiece, in particular when machining thin-walled profiles due to their low stiffness. The effects of manufacturing can be investigated with the help of finite element analysis. Hence different combinations of process parameter values can be virtually analyzed to select the most suitable ones. Modern joining techniques such as hydroforming, rolling-in or electromagnetical forming processes need a precise and reproducible preparation of the surfaces that are responsible for the strength of the connection of two joined elements. These functional surfaces can be flexibly manufactured by simultaneous five axis milling. This method provides a high flexibility in preparing dedicated macrostructures and microstructures for different joining methods, e. g. to increase tensile and torsional strengths. This article describes the development of adequate strategies for simulating and machining elements of modern lightweight frame structures.