Spindle apparatus

摘要

A spindle apparatus of a machine tool comprises a main spindle (5) rotatably supported in a housing (2) via bearings (3a, 3b, 4). A helium circulation system is provided for introducing helium, lower in density and fluid pressure than air, through a helium supply port (28) into a gap on the outer periphery of the main spindle within the housing (2), and for discharging helium to the outside through a helium discharge port (29). The main spindle (5) is rotated in an atmosphere of the helium. The spindle apparatus is simple in structure, but can minimize the power loss of the main spindle (5) and reduce the motor power, and also gives a cooling effect.