| 摘要 |
A drilling machine of the woodpecker type employs a spindle carrying a drill. The spindle is mounted for rotation in a housing having an attached feed screw and those members form an assembly that can be axially moved while the spindle rotates to enable the drill to be fed toward and retracted away from the work. The feed screw is engaged by a nut whose position is controlled by a rapid traverse mecahnism which can rapidly retract the spindle away from the work and can rapidly advance the spindle toward the work. The rapid traverse mechanism holds the nut fixed in position in the interval between rapid advance and rapid retraction. A peck feed mechanism is connected to the feed screw and repetitively feeds the spindle toward the work by causing the feed screw to progressively advance into the nut in the intervals when the nut is fixed in position. A hitch feed is coupled to the feed screw and acts to prevent the drill from bottoming in the hole on rapid advance. A trigger mechanism is arranged to be fired upon drilling of the hole to a predetermined depth. Upon firing, the trigger mechanism causes the feed screw to be disengaged from the hitch feed and from the peck feed mechanism whereby the feed screw is enabled to return to a starting position relative to the nut.
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