A main shaft device for machine tools designed to prevent the wasting of cutting
fluid mists and contamination of a machining environment with cutting fluid mists
by feeding optimum amounts of cutting fluid mists in a variety of machining operations,
comprising a mist feed tube (14) disposed in the rotational center of a
main shaft (2) driven for rotation, the front of the mist feed tube (14)
being inserted in the 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 the front end
surface of a cutting tool (17) fixed to the tool holder (8), via
a mist passageway (h1) in the tool holder (8), the main shaft device
being characterized in that the mist feed tube (14) has an adjusting nozzle
member (16) removably fixed to the front thereof for controlling the flow
rate of the cutting fluid mists flowing out of the feed tube (14) into the
mist passageway of the tool holder (8).
