PURPOSE: To lighten the thermal stress due to difference in thermal expansion for preventing an inner race of a bearing from cracking by performing channel working for reducing contact area in the time of shrinkage fit on one of the inner periphery surface of inner race of a ceramic bearing or the outer periphery surface of a metal shaft.
CONSTITUTION: A ceramic bearing 4, composed of a ceramic bearing inner race 2 and a ceramic bearing outer race 3 between which have ball bearings 1, is fixed integrally to outer periphery of a metal shaft 5 through shrinkage fit. In this case, many channels 6, which are parallel to the axial center of the metal shaft 5 and have equal intervals, are formed previously on the outer periphery face of the metal shaft 5 or on the inner periphery face of the ceramic bearing inner race 2, then shrinkage fit is made to perform after that. Working in channel is performed on one or both of the outer periphery face of the metal shaft 5 and the inner periphery face of the ceramic bearing inner race 2. When the bearing inner race 2 and the shaft 5 are made to contact together in reduced contact area with forming channels 6 in such manner, thermal stress in periphery direction and radial direction based on difference in thermal expansion of the bearing 4 and the shaft 5 due to the difference of temperature in time of assembling and operating can be reduced through releasing and dispersing them.