| 摘要 |
A positive feed drill has an elongated spindle mounted for reversible longitudinal motion in a drill housing. The spindle has a hexagonal cross-section with the apices of the hexagon being threaded. A toothed drive gear having a hexagonal aperture centrally thereof has a close sliding fit with the spindle for imparting rotation thereto. A feed gear threadedly engages the spindle apices and is selectively rotated at a different rotational speed than the drive gear to correspondingly longitudinally advance and retract the spindle. A pneumatic circuit provides completely automatic drilling to an adjustable depth and a positive retraction of the spindle. This circuit is novel in that it is contained internally within certain of the drill frame members.
|
