Friction-spinning – Interesting Approach to Manufacture of Complex Sheet Metal Parts and Tubes

AbstractFriction-spinning is an innovative incremental forming process that permits the defined adjustment of material properties in a particularly precise manner. The process is characterised by the use of process elements from both metal spinning and friction welding. As the workpieces are being processed, friction sub-processes are employed to achieve self-induced heat generation. Compared with conventional spinning processes, this in-process heat treatment permits the extension of existing forming limits and allows more complex geometries to be achieved, together with defined, favourable part properties. The process thus holds a high potential for the manufacture of functionally graded workpieces, such as complex hollow parts made from tubes and sheets. In order to achieve functional gradation, i.e. to influence the material properties (strength or grain size) in a defined manner, it is essential to be able to set specific temperature profiles. It would be possible to influence these profiles by selecting appropriate process parameters like the feed rate, relative motion and the coefficient of friction. The process characteristics of friction-spinning make it eminently suited to tube processing. A further approach to the manufacture of parts with functionally graded areas is the use of sheet metal blanks as another semi-finished product. The paper will present the corresponding results of basic research into the manufacture of sheet metal parts with the aid of friction-spinning. Here, the influence of significant process parameters, forming strategies and tool systems on both the course and the outcome of the friction-spinning process will be shown. In addition, the differences and correlations that exist between tube and sheet processing will be described and discussed on the basis of parts made of tubes and sheets. These parts are manufactured by the friction-spinning process employing different process strategies and tool setups