Experimental observations of AA6061-T6 round extrusions under a cutting deformation mode with a deflector

Abstract

A cutting deformation mode of AA6061-T6 round extrusions initiated by a heat-treated 4140 steel alloy cutter incorporating a deflector was investigated experimentally considering the load/displacement and energy absorption characteristics. Two different geometries of the cone-shaped deflectors, namely, straight and curved profiles, were considered in this research. The tubular specimens utilised in this experimental investigation were round AA6061-T6 tubes of lengths 200 mm with a nominal wall thickness of 3.175 mm and an external diameter of 50.8 mm. In addition to these specimens, additional extrusions were tested such that a progressive folding and global bending deformation mode was observed. Specimens which experienced global bending were of identical cross-sectional geometry as the extrusions which experienced cutting; however, the lengths of these extrusions were 300 mm. Results from the experimental tests showed that the cutter penetrated through the extrusion and formed petalled sidewalls which contacted the deflector and initiated bending in the petalled sidewalls. An almost constant cutting force, of magnitude 45 kN, was observed for the cutting deformation mode without the deflector. The presence of the straight or curved deflectors generated fluctuations in the cutting force which were significantly less than the variations in load for the specimens which experienced progressive folding, resulting in an increase in the crush force efficiency. As a result of the bending imposed on the petalled sidewalls from the deflector, a reduction in the steady state cutting force, to approximately 37 kN, was observed.