2Wu Shichun,Zhu Zhiwen.The cavity defect during cup-Bar combined extrusion.Proceeding of joint symposium on coldforging[C].Tokyo,1987.
3Johnson W,Mellor P B.Engineering Plasticity[M].London:VNR,1973.
4KudoH.Some analytical and experimental studies of axi-symmetric cold forging and extrusion[J].International Journal of Mechanical Sciences,1961,3 (1-2):91-106.
