焼入鋼の残留応力におよぼす研削の影響

Abstract

Generation of and change in residual stress are effected in-grinding operation owing to the interaction of the high-speed rotating wheel and the work. As the residual stress existing inside the steel is related to and reflects heavily on the fatigue life, a comparative study was made of the generation of and change in residual stress caused by grinding on a few types of steel, differences in heat treatment, grinding burn, residual stress, etc. The findings revealed the change in residual stress owing to wet grinding to be approximately 15 kg/mm2 less than that by dry grinding, and thus the following tests were conducted with dry grinding. Irrespective of the type of residual stress of the quenched steel, whether it be thermal or transformative, the change in residual tension stress was found to be most outstanding on the ground part, when ground under conditions indicated in table 3. The change in surface residual stress is relatively greater in quenched steel than in quenched and tempered steel. Also, increase of carbon contents (S25C, S45C, S55C, SK3) effect a remarkable change in surface residual tension stress. It is further greater in SUJ2 bearing steel. SNC22 carburized steel and SK3 were similar in this respect. Grinding burn and surface residual stress in SNC22 carburized steel are correlated and the change in the vicinity of the boundary of the grinding burn is approximately +20 kg/mm2 and around the area burned to a dark-brown color by abnormal grinding was acknowledged to be approximately +40 kg/mm2.