Wrinkle analysis and control of tube bending for hydroforming

In order to avoid the defects during tube bending, the computer numerical control (CNC) bending process is investigated. The influence of different bend radius, the clearance between the mandrel and tube, the position of mandrel and with or without wiper die for the wrinkle is discussed by using simulation and experimental method. The simulation and experimental results show that with the increasing of bend radius, the diameter of mandrel, the extending of the mandrel and with the wiper die, the trend of wrinkles is reduced. According to simulation, the experiment is conducted and the result of experiment is agreed well with the simulation result. The wrinkles are avoided and the eligible bend prototype is made which is satisfied the hydroforming of an engine cradle by using 2D bending radius and the clearance between the mandrel and tube of 0.015D.