Bending die is the key technology of sucessful bending.One side of pipe is compressed and easily come wrinkle, but the other side is stretched and easily become thinner while bending pipe, and due to external tensile and compression combination make section of workpiece become oval,it's more easily become wrinkle and oval while pipe is small and thin. How to reduce pipe deformation is the key point of this technology reserach. Pipe end forming equipment R&D department have involved in researching bending die. Now they have got a number of technological breakthroughs and invention patents, this high precision bending die reached the advanced international level and has been exported to the United States,Europe and other developed countries in recent years.