Influence of Spiral Tool Path Strategy Towards Incremental Backward Hole-flanging process using Curved Shoulder Forming Tool on Copper Sheet

Abstract

Many studies have been done as hole flanges have important functional elements in many lightweight construction parts such as to provide sufficient fastening area, stiffness, bearing support, and allow for positioning, etc. Advancement of CAD/CAM software integrated to CNC machines technology has opened a new technology to enable pre-cut hole on sheet metal formed incrementally into required flange profile and height on its periphery known as incremental hole-flanging (IHF). Unlike conventional hole-flanging, the forming of the flange in the IHF process was using a simple tool pressed incrementally into a pre-cut hole with motion path performed by the NC programs on CNC machine. Hence, low volume production and rapid prototyping to reduce initial cost can be achieved to meet today’s production flexibility. There have not been many types of research to study the forming of flanges in incremental backward hole-flanging (IBHF) of closed or semi-closed profiles. By employing full factorial experimental design, this research focused on whether curved shoulder flange forming tool, process variables, and tool geometry of IBHF on copper plate through a spiral tool path strategy affect the produced flange height. The research yielded the results that the curved shoulder flange forming tool was successfully produced flange height through the spiral path strategy. From the data processing, it is shown that the variable of horizontally forming step, the forming rate, the forming tool rotation, and the tool shoulder radius significantly affects the flange height resulted from the IBHF process.