Patent GB-797760-A (GB)
Title: An improved drilling machine more particularly for drilling deep holes
IPC: B23Q11/04
Filed: 1955-06-20
Abstract: 797,760. Drilling-machine details. MASCHINENFABRIK AUGSBURG - NURNBERG, AKT.-GES. June 20, 1955 [June 18, 1954], No. 17730/55. Class 83 (3). A drilling-machine, particularly for drilling long-holes, comprises devices for withdrawing the or each drill upon excessive resistance to feed-pressure or torque. Excessive torque initiates a swarf-clearance withdrawal and return of the drills, effected by the spindledriving motor 2, to a position short of the position previously reached, while the leadscrew 37 continues to be rotated by a separate motor; excessive resistance to feed-pressure initiates withdrawal of the drills, by a highspeed motor driving the lead-screw in reverse, to the starting-position, where they are stopped for examination. The drill-spindle 42 or several parallel-spindles are driven from the motor 2 through gears 3, 5, 7, 8, which rotate a sleeve 9 for each drill-spindle, the train of gears 8 being interconnected by intermediate gears. A clutch 13 with co-operating toothedelements 12, 14, transmits the drive of each sleeve 9 to an inner sleeve 16 splined at 17 to the element 14 and at 58 to the drill-spindle 42. The displaceable element 14 of the clutch is forced against the part 12 by a pack of spring washers 18 compressed to the required extent by a screw-threaded cap 19 engaging the part 12, and is displaced against the washers 18 to close a switch 24, by members 21, 22 upon excessive torsional-resistance to drilling. The switch energizes an electromagnet which withdraws a pin 32b (Fig. 3, not shown), from a pocket in the perimeter of a toothed-disc 32, the pin also closing a further switch to energize an electro-magnet which engages a clutch 28 and thus couples the drive from teeth 11 on one of the sleeves 9 to a bevel-gear 31 meshing with the disc 32. The latter is connected to the spindle-sleeves 41 by an eccentric-pin 38 supporting a block 39 which slides between guides 40, connected to the spindle sleeves 41, as the disc is rotated, thus withdrawing the drills in relation to the drill-head 4 to clear swarf. The clutch 28 is disconnected just before the pin 32b has completely returned into its pocket in the disc, which resumes its initial position, due to its inertia, after completing a revolution. A bevel gear 34 on the shaft of the disc 32 rotates a nut 36 on the lead-screw 37 during the swarf clearance operation to cancel the feed of the drill-head by the leadscrew, which continues to rotate during this operation, the drill-head thus being withdrawn slightly and the drilling-operation resumed short of the position previously reached. Spring-washers 44, compressed within the end of each spindle-sleeve 41 by a nut 49 locked by an outer-nut 51, apply the drilling-pressure to the spindles 42, and further compression of these washers, upon excessive drilling-pressure, displaces the spindle in the sleeve, closing a switch through contact between a ball-race 53 on the spindle and a switch operating lever 54 mounted on the sleeve and effecting withdrawal of the drill-head through a rapid traverse motor driving the lead-screw. The drill-head may also be withdrawn to its starting position by closing a hand-operated switch connected in parallel with the latter switch.