BUILT-IN MOTOR MAIN SPINDLE AND SUPERFINISHING MACHINE EMPLOYING THE SAME

Japanese Patent JP3814783

B2

PROBLEM TO BE SOLVED: To provide a built-in motor main spindle which is easy to assemble and replace a bearing by a relatively simple and compact structure, can rotate at high speed and reduces the occurrence of vibrations as much as possible, and a superfinishing machine employing the main spindle. SOLUTION: A rotary shaft 2 having a motor rotor 5 fixed to the middle is supported at both ends by ball bearings 3 and 4 inside a housing 1 containing a motor stator 6. One of the ball bearings 4 is received in a bearing case 11 detachably inserted into the housing 1, whereby the ball bearing 3 of an arbitrary size can be used irrespective of dimensions of the motor stator 6 and the motor rotor 5. This enables high speed rotation, can suppress the occurrence of vibrations, and facilitates operations of assembly and replacement of the bearings. In employing the built-in motor main spindle in the superfinishing machine, a coolant used for superfinishing serves as cooling liquid, thereby dispensing with a dedicated cooler and reducing the cost.