PURPOSE: To improve the workability in drilling a hole by cutting the chip to be produced during the drilling operation by the automatic feeding into an appropriate length in a drilling machine.
CONSTITUTION: A worm 10 and a sleeve 13 to automatically feed a spindle 6 are pivotably fitted to a worm shaft 11 in a slidable manner, a sleeve 14 is fixed to a worm bearing part 11a, and a plurality of steel balls 16 which are held at the specified space in the circumferential direction are held by a retainer 15 which is rotatably arranged between the sleeves 13, 14. A plurality of recessed parts are provide in the abutting surface of the steel balls 16 of the sleeve 14, and when the worm shaft 11 is rotated, the steel balls 16 are revoluted around the worm shaft 11 and enter the recessed parts while being rotated, and the worm 10 is moved to the sleeve 13 side, and the spindle 6 is temporarily retracted. The continuous chip to be produced during the drilling operation is cut.
YOKOYAMA MITSUMASA
INNAMI TATSUO
