Abstract: In view of the problems in the bending forging of coupler yokes, such as excessive bending force, thinning, galling and cracking in the root part of yokes, finite element simulation analysis on the bending forming process is carried out by means of a forging analysis software. The bending mechanism and the causes of defects are analyzed. In the light of the idea of “segment bending”, i.e. “prebending and secondary bending”, a new structure of skew bending die for forging coupler yokes, which is applicable to universal forging equipment, is proposed. The influences of factors such as prebending slope, concave die roller diameter, gap between concave die and punch, and punch corner radius on maximum bending force and maximum damage value are researched. Rational structural parameter values are obtained through numerical analysis and practical experience, thus eliminating the possible defects in the bending process, effectively decreasing the maximum bending force, and improving the quality of bending parts. Finally, the research contents are verified through tests.

Key words: Forged coupler yoke, Prebending, Segment bending, Structural parameters of bending die, Constitutive model, Creep ductility model, Finite element simulation, Rupture time prediction, Creep