GB300801A - Improvements in automatic drilling machines - Google Patents

Abstract

300,801. Armstrong, J. J. V., (Kingsbury, E. J.). Nov. 30, 1927. Drilling-machines. - In a drilling-machine having a yielding feed, the spindle-sleeve is fed by gearing including a worm drive, the worm of which is axially movable and rotated through a friction clutch, so that when the drill encounters resistance the rotation of the worm-wheel will be impeded and the worm will screw itself along axially to relieve the friction clutch. A stopmotion is also provided, in which the wormwheel is positively prevented from rotating and the friction clutch becomes completely disengaged. The drill-spindle 3, Fig. 2, is slidably keyed within a sleeve 4 rotated through gearing 7 from a motor, and is rotatable within a sleeve 9 adapted to be fed axially by a pinion 13, the journal and thrust ball bearings 10, 11 being provided in the sleeve. The pinion 13 is rotated alternately in opposite directions by a co-axial pinion 15, Fig. 7, engaged bv a toothed segment 17 oscillated about a pivot 18 by a roller 19 thereon and a cam groove 20 in a disc 21 keyed to a shaft 22, Fig. 6, which is driven by a wormwheel 23. The worm 24 is rotated from the spindle-sleeve 4 by gearing 31 and a friction clutch 29, 30, the action being such that when rotation of the worm-wheel 23 is impeded owing to the drill encountering resistance, the worm will overcome an adjustable spring 34 and screw itself along axially to separate the parts of the clutch, the feed being restored by the spring 34 when the resistance is removed. To stop the reciprocation of the drill-spindle at any predetermined point (preferably in its rearmost position) a lever 41 Fig. 7, is moved to bring a projection 42a thereon into the path of a stop 40 on the cam disc 21 and thus cause the friction clutch to be opened. The lever 41, pivoted at 18, is normally pressed upwardly by a spring 42, but may be depressed to cause the spindle to be fed by means of a hand lever 43 pivoted at 44 and carrying a link 45. The hand lever is normally pressed upwards by a spring 46, and an adjustable stop 44a serves to position the projection 42<a> correctly. The pinion 15 is angularly adjustable on its shaft by means of a conicallyshaped coupling and a nut on the end of the shaft.