GB239837A - Improvements in machines for drilling precious stones, in particular diamond drawing dies - Google Patents

Abstract

239,837. Patent-Treuhand-Ges f³r Elektrische Gl³hlampen. Sept. 10, 1924, [Convention date]. Drilling-machines.-In a machine for drilling precious stones, particularly diamond drawing dies, the feed of the die to the drill is automatically stopped after a predetermined amount of movement due to wear of the drill has taken place, in order that the thickened part of the drill may not contact with the work and enlarge the hole. The die h is secured to a holder g by soldering in the usual manner, and the holder is reciprocated relatively to the rotary drill c by an adjustable spring l and cam n acting through a lever o, the holder being supported on rollers f. A bar q slidable in a bearing p adjacent the work-holder carries an adjustable collar w adapted to contact with a stop x on the holder. In operation, the work is fed against the stationary drill and the collar w is adjusted so as to contact with the stop x. A plate t. of a thickness equal to the permissible wear of the drill, is then moved by a lever u between the bar q and a fixture s in order to displace the collar against the action of a spring r by an amount equal to the thickness of the plate t and a rod v. also on the lever u, simultaneously locks the collar against displacement. On rotating the drill and the cam the machine operates until the stops w, x again make contact. This contact may complete an electric circuit to operate one or more signals such as lamps, bells, drop-signals &c., and may also serve to stop rotation of the cam n and apply an electromagnetic brake to the drill-spindle. In modifications, the collar w may be fixed and the stop x adjustable, on the workholder, or both may be adjustable, and the adjustment may be effected by a screwed spindle. The plate t is removable to vary the feed, and means other than the cam n may be employed to retract the work periodically.