New point envelope forming technology of cylindrical parts with thin wall and large height

Axial ring rolling (ARR) is a new technology for rolling cylindrical parts with thin wall and large height (CPTWLH) utilized on aerospace equipment. However, the theoretical contact between molds and CPTWLH in ARR is line contact, resulting in large forming force. Aimed at this issue, a new point envelope forming (PEF) technology of CPTWLH is proposed in this paper to greatly reduce forming force. In PEF of CPTWLH, idle mold with spherical loading surface not only rotates around its axis but also makes round-trip rolling motion along the axial direction. Hence, the theoretical contact between idle mold and CPTWLH is point contact in PEF of CPTWLH, and the forming force can be greatly reduced. In regard to this new technology, a mathematical model is established to calculate the wall thickness of CPTWLH and establish the criteria of that CPTWLH can be formed by PEF. Based on this mathematical model, the effects of key parameters on the wall thickness distribution of CPTWLH are revealed, and the window of that CPTWLH can be formed by PEF is established. Through FE simulation, the deformation characteristics in ARR/PEF of CPTWLH are contrastively analyzed. It is found that the proposed PEF is effective in forming CPTWLH. Moreover, compared with ARR of CPTWLH, the forming force is greatly reduced, and meanwhile, the deformation uniformity is greatly improved in PEF of CPTWLH. Through the PEF experiment, it is verified that the established mathematical model in this paper is reliable in calculating wall thickness of CPTWLH in PEF.