D. H. Lammlein, Welding Automation Laboratory Vanderbilt University, Nashville, TN; T. J. Lienert, M. Bement, Los Alamos National Laboratory, Los Alamos, NM; D. DeLapp, G. Cook, A. Strauss, T. Bloodworth, P. Fleming, T. Prater, M. Wilkes, Vanderbilt Univertsity, Nashville, TN
Demonstration has shown that the Friction Stir Welding of closed contours can be accomplished via the gradual insertion and retraction of a tool pin relative to its shoulder during the weld traverse. In this work, a novel method of pin retraction and shoulder force control is implemented. In this method, a Bellville disc spring stack is used to maintain shoulder pressure on the workpiece throughout the welding process. This process involves simultaneous movement in the traverse and plunge axes; the automated axes of a vertical mill are used to accomplish this. A four axis dynamometer is integrated into this setup for the purposes of mechanistic analysis and design optimization. A Matlab Simulink model is used to analyze the effect that the cyclic forces common to FSW have on the displacements of and forces in various tool apparatus components and in the workpiece. The tool apparatus design allows for adjustability based on those analyses as well as adjustability to various FSW process parameters via the insertion or removal of springs, the movement of a plate backing the spring stack, and by the swapping of the tool pins.
Summary: Demonstration has shown that the Friction Stir Welding of closed contours can be accomplished via the gradual insertion and retraction of a tool pin relative to its shoulder during the weld traverse. In this work, a novel method of pin retraction and shoulder force control is implemented. In this method, a Bellville disc spring stack is used to maintain shoulder pressure on the workpiece throughout the welding process. This process involves simultaneous movement in the traverse and plunge axes; the automated axes of a vertical mill are used to accomplish this. A four axis dynamometer is integrated into this setup for the purposes of mechanistic analysis and design optimization. A Matlab Simulink model is used to analyze the effect that the cyclic forces common to FSW have on the displacements of and forces in various tool apparatus components and in the workpiece. The tool apparatus design allows for adjustability based on those analyses as well as adjustability to various FSW process parameters via the insertion or removal of springs, the movement of a plate backing the spring stack, and by the swapping of the tool pins.
