Hot and warm cross-wedge rolling of ball pins – Comparative analysis

Abstract

Cross-wedge rolling is a process conducted mainly in hot forming conditions. Warm forming is a compromise between hot and cold forming. This paper presents the results of a comparative analysis of warm and hot rolling of ball-shaped pins. Rolling process was controlled in terms of energy consumption, load and abrasive wear of tools. Warm cross-wedge rolling is more economical due to the low energy consumption required to heat the billet. Warm rolling can be less cost-effective due to faster tools wear. Faster tool wear during rolling in warm conditions may generate additional cost connected to regeneration and more frequent tool replacement. The stress and strain during the rolling at different temperatures was analysed. The variable nature of stress during cross-wedge rolling is more advantageous during hot rolling due to the lower amplitude of stress changes. Particular attention was paid to the quality of elements and difficulties resulting from rolling at lower temperatures. The influence of the rolling temperature on the quality of the microstructure of the rolled products was demonstrated. It was proved that during the warm rolling, the material may be strengthened due to deformation.