Abstract: Nuclear main pipe is one of key components of pressurized water reactor. The grain refinement of 316LN steel used in nuclear main pipes of AP1000 could not be completed by heat treatment and the mixed grain caused by forging nonuniformity could not be eliminated finally. Consequently, the forging process will be the key way to solve this problem. Based on the strain distribution of upper flat and lower V-shaped anvil in the stretching process, the relationship between rotation angle, V-shaped anvil angle and reduction rate is given quantificationally after theoretical analysis. The rotation processes of “double-press process” is improved and “three-press process” is brought. Numerical simulation results show that the new rotation process of upper flat and lower V-shaped anvil improve the circumferential deformation uniformity of forgings and the effect is better while it is closer to surface. Big fillet V-shaped anvil can be used instead of general V-shaped anvil to improve the hard deformation area at the center of the forging during rotation processing. The results have theoretical referenced value to make and optimize forging process of nuclear main pipes.

Key words: Forging, Heavy forgings, Simulation, Uniformity, humanoid Motion, Human-Posture Recognition, Human-Robot Motion Mapping, Manipulator