Experimental and numerical study on the single point incremental forming of two sheet layers

Single point incremental forming (SPIF) is a sheet metal forming method that the metal sheet is locally and gradually deformed into the certain shapes by a semi-sphere tool controlled by CNC machine. SPIF is a promising method for small batch production with high flexibility and low price. Many previous studied were performed with one sheet layer to form the truncated pyramidal shape. The previous results showed that the sheet blank was formed in the wall area without drawing phenomenon in the blank shoulder area; the thickness distribution followed the sine law and the vertical step size effected strongly on the surface quality. With two sheet layers included stainless steel STS304 above and aluminum AL3004-P beneath, the single point incremental forming process shows the different results that the second sheet layer tends to be drawn at outer periphery and improved profile accuracy. In this study, we perform the experiment design using Taguchi method to find the effect of each forming variables on the drawing distance and springback. According to the experiments, blank size is the most effected on the drawing distance and springback is the most related to forming angle. The finite element simulation by ABAQUS Explicit software is applied to clarify the drawing phenomenon. The experimental and numerical results are compared and discussed.