Patent ID: 6923604

Claim:
A spindle device of a machine tool comprising: a spindle ( 2 ) driven for rotation, said spindle having an inside hole at the center; a straight feed pipe ( 14 ) formed of a double tube having an inside tube ( 14 a ) and an outside tube ( 14 b ) the straight feed pipe being in the inside hole in a non-rotating state and out of contact with the spindle, coolant being fed into said inside tube ( 14 a ), and compressed air being fed into said outside tube ( 14 b ); a mist generating member ( 16 ) provided near an inside tip part of the spindle, said mist generating member being formed by the inside tube ( 14 a ) and the outside tube ( 14 b ), and a mist outlet member ( 23 ) in and integral with said outside tube ( 14 b ), said mist outlet member defining a mist outlet passage (c); and a mist guiding extension member ( 24 ) extending adjacent to a rear end part of a tool in a center hole of a tool holder ( 8 ), the extension member being integral with said spindle, said mist guiding extension member having a mist guiding passage (f) in communication with the mist outlet passage (c) of said mist outlet member ( 23 ) through both a rotary joint ( 25 ) and a pressing tube member ( 27 ).