Numerical simulation and experimental study on cyclic multi-point incremental forming process

Cyclic multi-point incremental forming (CMPIF) is a new flexible forming process derived from multi-point forming (MPF) and single-point incremental forming (SPIF) methods. In MPF process, the pins are positioned to special locations and fixed together as the discrete upper/lower die with cooperation of a hydraulic/mechanical press to form a part in several seconds. Similar to MPF process, the proposed CMPIF process is also with discretized dies consisted of a matrix of pins. However, its pins are cyclically controlled to move a small step until all pins approximated gradually to the final shape of the part. Therefore, the forming force of CMPIF process is relative smaller than that of MPF process as well as the energy consumption. In this paper, the CMPIF process was simulated by using a mild steel Q235B plate in MSC.Marc®. An experimental setup to perform the CMPIF process was designed and realized. The pins were driven by threaded rods with spherical hinge at the head to eliminate local dimples. The pins were driven manually to move forward to form a flat plate into the desired final shape. The final shape of workpiece was scanned by a 3D laser scanning system and reconstructed to a 3D surface. The experimental results were compared to that of numerical simulation. It could be seen that the doubly curved plate can be formed effectively by the CMPIF method.