Patent ID: 6860683

Claim:
A spindle assembly for a machine tool, comprising: a spindle mounted within a spindle housing for rotation and translation; a collet directly securing and releasing a tool inside the spindle; a draw bar, one end of which is connected to the collet through a sleeve within the spindle to operate the collet, the draw bar being rotatably driven together with the spindle; a piston and a cylinder connected to the draw bar to move the draw bar in forward and reverse directions along a lone-axis of the spindle; a rotary joint for supplying cutting oil to the spindle; a connecting adaptor connected to a rear outer circumference of the draw bar within a rear end portion of the spindle, the connecting adaptor supporting a rear end of the draw bar in such a manner as to allow for motion in the lone axis direction of the spindle; a pusher connecting one end of the rotary joint and the connecting adaptor at the rear end portion of the spindle, the pusher being mounted such that the pusher may partly be inserted into and removed from the inside of the rear end portion of the spindle; and a ring-shaped bushing interposed between an inner surface of the spindle and an outer surface of the connecting adaptor and the pusher, the bushing acting as a guide to allow the sliding of the connecting adaptor and the pusher along the inner surface of the spindle and along the long axis direction of the spindle.