Patent ID: 6905294

Claim:
A main shaft device for machine tools comprising: a main shaft ( 2 ) having a front and a rear; a tool holder ( 8 ) fixed on the front of said main shaft ( 2 ), said tool holder ( 8 ) including a holder body ( 8 a ) supported by the main shaft ( 2 ), the holder body having a front and a center; a chuck ( 18 ) mounted on the front of the holder body ( 8 a ); and a cutting tool stopper member ( 20 ) mounted in the center of the holder body ( 8 a ), said cutting tool stopper member touching a rear end of a cutting tool ( 17 ) clamped by the chuck ( 18 ) to control backward displacement of the cutting tool ( 17 ); and an arrangement spouting cutting fluid mists fed into the rear of the main shaft ( 2 ) from a front end surface of the cutting tool ( 17 ) through mist passageways formed in each of the cutting tool stopper member ( 20 ) and the cutting tool ( 17 ), wherein the cutting tool stopper member ( 20 ) has a main body member ( 22 ) having a front, and a front member ( 23 ) exchangeably fixed to the front of the main body member ( 22 ) to serve as an adjusting nozzle member for controlling the flow rate of cutting fluid mists flowing out of the main body member ( 22 ) into the cutting tool ( 17 ).