Process limits for incremental flanging and hole flanging operations using a CNC controlled forming tool

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Incremental sheet forming (ISF) offers a set of technological advantages and potentials. These include low part specific tooling, high flexibility due to short ramp up times and increased forming limits. Especially the recently developed process combinations (e.g. the combination of stretch forming and ISF) offer the possibility of low cost production of complex sheet metal parts meeting low tooling demand and reduced process times. Thus, the technological progress has reached a state that requires investigations of the complete process chain. Beside the primary forming and trimming steps finishing operations, such as flanging and hole flanging for the introduction of functional elements, are part of the complete manufacturing process. Therefore systematic studies on the application of ISF for forming of these elements are carried out within this work. The overall objective of the project is to explore the fundamentals of flanging as well as hole flanging operations by ISF and to enable the technological requirements for the use of these finishing operations by ISF. In the first project period a basic understanding of the process has been established. Individual influences of single process parameters was considered and analysed. It was shown that the incremental forming character allows (significant) extension of known process limitations of conventional forming operations. In the proposed research period the compiled knowledge is to be made accessible in a commonly applied CAM tool. A direct implementation of the follow-up operations in the computer aided manufacturing (CAM) routine is a requirement for an efficient use of the shown technology potentials. Furthermore, the achievable hole flange properties are to be optimized with respect to the resulting geometrical accuracy. To fully utilize the demonstrated potential of incremental hole flanging operations it is mandatory to meet the geometrical accuracy (wall angle of 90°). Additionally the influence of pre-forming steps is to be analysed. Therefore it is to be examined to what extent the identified high forming limits are transferable to a subsequent processing of preformed components. Finally, the obtained results are transferred to a complex application component.