Hybrid machining of roller bearing inner rings by hard turning and deep rolling

Hard turning and deep rolling are two processes with high potential to face the challenge of highly flexible and productive machining of hardened parts. On the one hand, the processes of grinding and honing are very productive to manufacture roller bearings, but on the other hand they are very inefficient for frequently changing part geometries. In addition, they do not lead to an increased endurance due to high compressive residual stresses. Hard turning and deep rolling are appropriate processes to achieve this. A hybrid process of hard turning and deep rolling can help to shorten the process chain and to optimize the influence on surface quality, because of defined contacts between tool and surface. A concept of machining roller bearing inner rings with a hybrid process is presented. A force model to predict the resulting turn-rolling forces is introduced. Additionally the effect of feed and the new process parameter shift in feed direction xf on surface roughness are discussed within this paper.