Plastic deformation behaviors of cold rotary forging under different contact patterns by 3D elastic-plastic FE method

Abstract

Cold rotary forging is an advanced but very complex incremental metal forming technology with multi-factors coupling interactive effects. The contact patterns between the upper die and workpiece have an essential effect on the cold rotary forging process. In the current work, a 3D elastic-plastic dynamic explicit FE model of cold rotary forging of a cylindrical workpiece is developed under the ABAQUS software environment and its validity has been verified by an experiment carried out on a T 200 cold rotary forging press. On the basis of this reliable 3D FE model, numerous simulation calculations have been carried out and it has been found that there are three new plastic deformation behaviors of cold rotary forging under three different contact patterns. With the first pattern, the middle part of the cylindrical workpiece is first penetrated axially from the upper surface to the lower surface by the plastic deformation zone (PDZ), and then the PDZ gradually develops radially towards the cylindrical surface until the entire cylindrical workpiece has become the PDZ. In the second situation, the PDZ gradually penetrates the axial height from the upper surface to the lower surface of the cylindrical workpiece. In the third situation, the upper region of the cylindrical workpiece is first penetrated radially from the cylindrical surface to the centre, and then the PDZ gradually develops axially towards the lower surface until the entire axial height has been penetrated completely. On the basis of these behaviors, the effects of three different contact patterns on the cold rotary forging process have been comprehensively investigated. The results of this research not only provide valuable guidelines for the design, installation and adjustment of dies in the cold rotary forging process, but also help to further understand the deformation mechanism of cold rotary forging. © 2009 The Japan Institute of Metals.