A new strategy for acquiring the forming parameters of a complex spatial tube product in free bending technology

Abstract Free bending technology is a new bending process for manufacturing freeform tube products. When manufacturing a complex spatial product, the variation of bending curvatures and torsions will accompany with a frequent changing of forming parameters, which will increase the manufacturing difficulties greatly. Until now, there is no effective way for determining the forming parameters of a complex spatial product precisely. In this paper, the characters of stable elements and unstable elements are analyzed. A mathematical collection is established for describing the geometrical characters of unstable elements. By using the new describing method, it is possible for establishing the relationship between the characteristics of unstable elements and forming parameters. And then a knowledge base can be built for storing the relationships. Based on these researches, a procedure for acquiring the forming parameters of a complex spatial tube product in free bending technology is proposed. The procedure can be described as follows: (1) use the known unstable elements in knowledge base to converge a complex spatial tube; (2) acquire its preforming parameters through the knowledge base; (3) compensate the motion of clamp to acquire the optimized forming parameters. The strategy is successfully applied on a typical spatial tube product and the final optimized forming parameters are exhibited.