Patent GB-803725-A (GB)
Title: Universal drilling machine
Inventor: JR RAYMOND JOSEPH DUNN
IPC: B23B39/24
Filed: 1956-12-03
Abstract: 803,725. Multiple-spindle drilling-machines. HARTFORD SPECIAL MACHINERY CO. Dec. 3, 1956, No. 36853/56. Class 83 (3). In an automatic multi-head drilling-machine, having tool-heads angularly spaced about a work-turret and with means for carrying one or a number of workpieces on the turret from one head to the next, the heads are controlled by cams adjustably-secured to a shaft coupled to the turret. The turret consists of a table 10, driven by a motor DM through a belt-driven shaft and clutch 19, Fig. 3, and worm-gears 16, 14. The clutch 19 is positive for forward drive, but slips when the index-plate 11 is reversely rotated to engage one of its teeth 60 with a stop 56. The table 10 is angularlyadjustable on the index-plate 11 by a pin 20 engaging one of the holes 20<SP>1</SP>, Figs. 3 and 6, and carries a spiral-gear 21 driving a spiral-gear 22 on a shaft 23, connected by a releasable-coupling 24 to a control-shaft 25, which carries a controlcam IC, Fig. 10, an indexing-cam FIC, and drill-head control-cams 1HC-4HC. Shaft 25 drives cams 1HC-4HC through frictionclutches 33; drives cam IC directly, and drives cam FIC through a 1: 2 reduction-gear 45, 49. Clutches 33 are engaged by an adjustablespring 41. The drill-heads 1H-4H are carried by pillars C on brackets K which are angularlyadjustable about the turret 10 by worms 4 on the brackets engaging an arcuate rack 5 on a control-support 13, clamping being effected by bolts and T-slots 3, 7. Operation. In an example described, for producing identical holes in eight workpieces spaced 45 degrees apart on turret 10, head 1H drills a small hole, head 2H enlarges part of this hole and heads 3H, 4H ream the two bores. In the starting-position, a tooth 60 of the indexplate 11 is pressed hard against the stop 56, and on manually-actuating a start-switch and a cycle-switch, head 1H is fed towards the first workpiece, either pneumatically or by a drive from the spindle-rotating-motor. After drilling to a predetermined depth, a limit-switch reverses the feed, but acts through a time-delay to allow the tool to clear the hole a solid depthstop (not shown), determining the exact depth of the hole. On return of head 1H, limit switches are operated to withdraw index-stop 60 and rotate the turret in the forward direction. The turret indexes the work, a latch-switch LLS opening as the latch disengages the index-plate 11, and the index-cam IC moves a lobe 69 away from a switch DLS. Simultaneously, the cam 1HC rotates with shaft 25 until contacting a limit-switch 83 (not shown), a solenoid releasing latch 94, Fig. 10, to free the cam 2HC. The assembly is arrested by a second lobe on cam IC, contacting the switch DLS, relays are energized, causing reversal of direction, and the assembly moves sufficiently to force the latch against the teeth of index-plate 11, the clutch 19, Fig. 3, preventing damage due to possible over-run of the motor D.M. The heads 1H, 2H approach the work, head 1H drilling a hole in the second workpiece and the head 2H enlarging part of the hole in the first workpiece. Similarly, heads 3H, 4H perform subsequent reaming-operations on the work, the indexing- cam FIC, due to its 1: 2 ratio with the turret, allowing the turret to rotate twice per cycle so that eight workpieces are machined by the four heads in one revolution of the turret. The drill-heads may operate horizontally, or at different inclinations, and may operate on a single workpiece indexed by the turret 10.