Experimental investigation of the forming parameters of the rotational upset forging process

In a conventional upset forging, the presence of friction at the tool–workpiece interface not only increases the forging pressure and force, but also leads to non-homogeneity of deformation. In this study, to solve the above problems, a parametric study is presented on a new rotational upset forging process. Twisting torque can change the harmful effect of friction into a useful effect. Experiments were carried out to generate data of forming parameters, which are the friction factor, the sliding factor, the punch velocity and the geometry of the billets, on the rotational upset forging process. Comparing with the conventional upset forging process, the rotational upset forging process reduces both the forming load and bulging. The deformation of rotational upset forging is more uniformly distributed and its total deformation is greater than that of conventional upset forging for the same reduction of height.