Robot-assisted Single Point Incremental Forming: Focus on shape accuracy of the final part

Abstract

Single Point Incremental Forming (SPIF) is regarded as an innovative and flexible manufacturing process able to produce complex shapes: in fact, the punch, moving along a toolpath, incrementally deforms a blank until the required geometry is reached. The literature reports two alternative routes for the SPIF process: (i) coupling the punch with a 3-axis CNC machine (conventional approach) or (ii) relying on the flexibility of an industrial robotic arm. However, the enhanced versatility of the latter option is partially counterbalanced by the lower stiffness of the kinematic chain: this, in turns, leads to a lower accuracy of the final part if compared with the conventional approach. Nevertheless, it should be also pointed out that, besides the stiffness of the manufacturing system, the definition of the tool trajectory is a key aspect and greatly influences the geometrical accuracy of the final part. In this work, an AA5754-H111 benchmark truncated cone was manufactured by means of a 6-axis robot and a 3-axis milling machine, using different levels of step down. Then, the formed parts were analyzed and compared in terms of shape accuracy and surface roughness, to provide insights into the trade-offs between flexibility and precision in SPIF.