Control of the fabrication of long slender workpieces of arbitrary shape. I. Open-loop control of the multi-axis bending process

Computer numerically controlled (CNC) multi-axis bending is a new metal forming technology used to fabricate long slender structural workpieces of arbitrary shape and cross section. Although this process can achieve high levels of flexibility and productivity over conventional forming processes, generating a control program to produce a desired shape is a laborious process involving the trial-and-error by a skilled engineer. A systematic method was developed to replace the manual control method. Since multi-axis bending is inherently a local deformation process, the concept of intrinsic part representation from differential geometry is applied as a basis to develop the part geometric model and process model. After being compensated for springback and die offset, the model is used to compute a set of initial control commands. The effectiveness of the model is demonstrated experimentally.