| 摘要 |
<p>In a vertical machining center, a tubular spindle-drive sleeve rotates about its longitudinal axis while axially immovable. A spindle is axially slidable in and rotatably driven by the sleeve. A linear drive, non-rotating ball screw connected to the upper end of the spindle is driven axially by a powered ball nut to advance and retract the spindle in the sleeve. A coupling plug fixed at the bottom of the spindle connects to any one of various toolholders in a turret. Axial movement of the spindle by the ball nut automatically couples and decouples the spindle to and from the toolholder. Gaseous or liquid fluid supply down through the spindle is provided. In one embodiment, an air motor is mounted inside the spindle and coupled to a second spindle in the changeable toolholder to supplement the main spindle drive and drive the toolholder spindle for driving a cutting tool at a much higher rotational rate than is possible with the main spindle alone.</p> |
