GB560555A - Portable rotary drilling machines - Google Patents

Abstract

560,555. Portable drilling-machines; chucks. CHICAGO PNEUMATIC TOOL CO. Jan. 28, 1943, No. 1464. Convention date, April 21, 1942. [Class 83 (iii)] In a portable drilling machine for mining &c. a hollow feed screw which contains the drill rod is rotated by a fluid pressure motor and a feed nut is also driven by the motor at a variable speed in excess of the screw speed, a countershaft which drives the screw and nut being parallel thereto. The machine comprises housings 38, 39, 41 for the motor and gearing, the housing 41 being pivoted at 19, Figs. 1 and 4, on a base 15 angularly adjustable on a bracket 17 carried by the strut 11 and being clamped in operative position by a bolt 26. The feed screw 82 is journalled at 77, 91 in the housing 41 and is driven by a sleeve 76 splined thereon carrying a gear 75 engaging gear 74 on the countershaft 69 driven at 68 from a pinion on the motor shaft. The nut 88 is rotatably mounted at 89, 91 and has four gears 92 of different size keyed thereto. Corresponding gears 93 are loose on the countershaft 69 and are selectively keyed thereto by a dog 96 attached by a spring detent in a transverse hole in a rod 98 axially slidable within the shaft. A sleeve 106 is pinned at 103 to the rod and is moved axially by rack teeth thereon engaged -by a pinion rotated by a hand lever 114, further teeth on the sleeve engaging a spring detent to hold the dog 96 in engagement with any of the gears 93 or in intermediate unclutched positions. Indications on the casing 41 co-operate with the lever 114 to show the setting. The screw 82 has a left-hand thread so that rotation of the screw and nut in a clockwise direction, as viewed from the rear of the machine, will cause the drill to be fed into the work, withdrawal being effected by holding, the nut against rotation whilst the dog 96 is in an unclutched position and the screw is driven by the motor. For this purpose a spring retracted plunger 117, Fig. 1, may be engaged with one of a series of apertures 119, Fig. 4, in the nut. When the drill has penetrated for the full stroke of the screw 82, radial screws 87 in the chuck 83 are loosened to release the jaws 85 from the drill and the screw is then withdrawn and engaged with another part of the drill for further feed. To withdraw the drill from the bore-hole, the machine is swung about its pivot 19 and an arm 32, Fig. 1, of an extracting device 28 is swung about its actuating plunger 31 to bring a gripping device 33 thereon into line with the drill. The plunger 31 operates in a cylinder 28 attached by a bracket 27 to the base plate 15 and is actuated by compressed air through a hand controlled valve 37. The dog 34 of the gripping device oscillates to grip and release the drill as the plunger reciprocates, and the drill is guided during withdrawal by an arm 35 rotated into alinement therewith together with the gripping device 33. The driving motor has a rotor 51, Fig. 8, with sliding vanes 52 operating in an eccentric chamber 47 which has ports 54, 56 for admission and exhaust. The supply of air to the motor is controlled by a hand operated valve 57, Fig. 1, and also by a piston valve 58, Fig. 8, acted upon by a lever 61 engaging a plunger, 59 under 'the influence of weighted arms 60 carried by the rotor, so that the supply will be throttled if the motor speed increases unduly. The driving pinion 67 is splined to the rotor to facilitate replacement.