A new hydroforming process for large elbow pipes

A new hydroforming process for manufacturing elbow pipes is proposed to overcome the difficulties in manufacturing large elbow pipes with conventional technologies. The stresses in a toroidal shell are analyzed and the final hydroforming pressure is given. The displacement, strain distribution, wrinkling and cross-section profile variation of the toroidal shell during the hydroforming process are discussed. The dimensions of the formed toroidal shell are measured. It is shown experimentally that the manufacturing of elbow pipes with the integral hydroforming process is feasible.