Reduction in axial forging load by low-frequency torsional oscillation in cold upsetting

Abstract

Torsional oscillation with a maximum frequency of 1.5 Hz was superposed with axial forging load to reduce the axial forging load in cold upsetting process. A cylindrical aluminum workpiece was twisted by rotating the lower die around the z-axis with a maximum alternating amplitude of 22.5° and a maximum angular speed of 0.5 rpm during cold upsetting process with a maximum compression speed of 0.1 mm/s. The torsional oscillation conditions for the load reduction were determined from theoretical and experimental results. It was found that the axial forging load was reduced by larger than 5% under the following conditions: rotation/compression speeds larger than approximately 15°/mm and torsion amplitudes larger than approximately 1°. A maximum reduction in the axial forging load of approximately 80% was obtained in upsetting with a rotation/compression speed with approximately 1700°/mm.