| 摘要 |
A drilling machine including a spindle and an elevating hollow shaft rotatable in unison with the spindle. An annular cutter is mounted in axial alignment with the hollow shaft and an elevating center drill is mounted in axial alignment with the annular cutter. The drill is movable to descend relative to the annular cutter to initiate the formation of a center hole in a workpiece prior to drilling. The drilling machine further includes a cylindrical member vertically movable and rotatably supported within a holder with the elevating hollow shaft being vertically movable and rotatably supported within the cylindrical member.
|
