| 摘要 |
A spindle unit of a machine tool, more enhancing a tool unclamping speed by concurrently applying restoration force of a return spring and hydraulic force when the tool is unclamped, comprises: a spindle rotating around a rotational axis; a draw bar installed within the spindle to be movable in the direction of the rotational axis of the spindle; a collet connected to a front end of the draw bar to clamp or unclamp the tool as the draw bar moves forwards or backwards; and an unclamp cylinder including a first piston installed at a rear side of the draw bar and arranged to be able to slide as far as possible to a first stroke within a housing and a second piston arranged to be able to slide as far as possible to a second stroke within the first piston, and making the second piston press the draw bar to move the draw bar forwards by moving the first piston forwards in a state of moving the second piston forwards. |
