Patent ID: 6899496

Claim:
A main shaft device for machine tools comprising: a main shaft ( 2 ) driven for rotation, said main shaft having a front, a rear and a rotational center; a mist feed tube ( 14 ) disposed in the rotational center of the main shaft ( 2 ), said mist feed tube feeding cutting fluid mists from the rear of the main shaft to the front thereof, said mist feed tube having a front end inserted in a mist passageway in a rotational center of a tool holder ( 8 ) fixed to the front of the main shaft ( 2 ) to ensure that the cutting fluid mists flowing out of the front end of the mist feed tube ( 14 ) spout from a front end surface of a cutting tool ( 17 ) fixed to the tool holder ( 8 ) via the mist passageway (h 1 ) in the tool holder ( 8 ), wherein the mist feed tube ( 14 ) has an adjusting nozzle member ( 16 ) changeably fixed to the front of the mist feed tube ( 14 ) for controlling the flow rate of cutting fluid mists flowing out of the mist feed tube into the mist passageway of the tool holder ( 8 ).