Patent ID: 7318692

Claim:
A spindle unit for a machine tool, comprising: a drive unit having a drive shaft and a rotor which is mounted in fixed rotative engagement to the drive shaft; a spindle head assembly having a hollow spindle head shaft driven by the drive unit; a tie rod arranged for axial displacement in the hollow spindle head shaft between rearward and forward positions and detachably coupled with the drive shaft; a collet placed in a pocket of the spindle head shaft and interacting with the tie rod to clamp a tool, when the tie rod assumes the rearward position, and to expel the tool, when the tie rod assumes the forward position; a bearing assembly supporting the drive shaft; and a shifting unit for moving the bearing assembly in axial direction to thereby displace the drive shaft together with the rotor and the tie rod between the rearward and forward positions, wherein the spindle head assembly and the drive unit are positioned in axially successive relationship and detachably connected to one another to allow an exchange of the tool, while the drive unit rotates.