Spindle device

A spindle device comprising:

• a spindle housing having a through hole;
• a spindle shaft inserted in the through hole;
• a rotating member disposed at one end of the spindle shaft and configured to rotate in linkage with rotation of the spindle shaft;
• and
• a motor disposed at another end of the spindle shaft and configured to rotate the spindle shaft, wherein:
• the rotating member has, formed therein, a suctioning passage through which air suctioned from outside flows;
• the spindle shaft has a first guide passage configured to guide air flowing through the suctioning passage to a clearance between an inner wall of the spindle housing defining the through hole and an outer wall of the spindle shaft facing the inner wall, by way of interior of the spindle shaft;
• and
• the spindle housing has, formed therein, a second guide passage configured to guide air guided to the clearance, to outside of the spindle housing, wherein
• the spindle housing has a third guide passage configured to guide air outside the spindle housing to the clearance, the third guide passage being formed so as not to communicate with the second guide passage;
• and
• an outflow port of the third guide passage is formed between a bearing configured to rotatably support the spindle shaft by a compressed gas and an inflow port of the second guide passage, wherein:
• the spindle housing includes a housing body provided with the bearing, and a joint portion provided so as to cover an outer peripheral surface of part of the spindle shaft between the housing body and the motor;
• and
• the second guide passage includes a joint passage portion formed in the joint portion and configured to communicate with the first guide passage, and a housing passage portion formed in the housing body and configured to allow the joint passage portion to communicate with the outside of the spindle housing.