Abstract
Three-dimensional free-bending is a new and an advanced forming technology to manufacture the complex metal hollow components with continuously varying radius. In this study, the principle, process analysis, and the CNC control of free-bending were introduced in detail. The characteristics of the free-bending process, such as the motion trace scope of bending die and the stress variation in the free-bending process, were numerically investigated through finite element method using ABAQUS finite element code. With the simulation model, the material correction factor (Km) of copper was determined and the correction factor (Kc) for the clearance between the tube and bending die was also proposed. Moreover, the effects of the key process parameters including the clearance between the tube and bending die (Delta c), the distance between the center of the bending die and the head of guide sleeve (A), and the axial feeding velocity (v) on the forming quality of the tubular bending components were studied as well. Through the finite element simulation and analysis, the optimum parameters (Km, Kc, Delta c, A, and v) used in the free-bending process of the tubular component are summarized and the forming process design of the copper tubular component was also obtained. Based on the forming process design, the simulation and bending test of the copper tubular component were carried out, and the dimensions of the bending components gave a very good agreement with the results obtained from finite element modeling. Furthermore, there was no obvious cross section distortion, excessive thickening, and thinning of wall thickness of the formed tubular components. It is concluded that the three-dimensional free-bending technology is a novel forming process used to manufacture a sound complex three-dimensional hollow component with asymmetric cross sections and continuous varying radii.