Patent GB-382678-A (GB)
Title: Improvements in or relating to rotary drills for drilling rock, coal and the like
IPC: E21B19/081
Filed: 1931-08-05
Abstract: 382,678. Drilling-machines. BRITISH JEFFREY-DIAMOND, Ltd., Stennard Works, Wakefield, Yorkshire.-(Assignees of Jeffrey, R. K. ; 8, Sessions Village, Columbus, Ohio, U.S.A.) Aug. 5, 1931, No. 22235. Convention date, Sept. 24, 1930. [Class 83 (iii).] In a rotary drilling-machine for operating on rock, coal &c., the drill is carried by a screwed spindle engaged by a nut and carries an independently rotated gear which is mounted concentrically with the spindle, axial movement of the gear in one direction causing the nut to be driven therefrom through a clutch in the same direction as the spindle but at a slightly different speed for a slow forward feed, and movement in the opposite direction causing the nut to be held stationary by a fixed clutch to give a rapid withdrawal. The machine comprises an airtight casing formed of parts 19, 20, 21, Fig. 3, enclosing the electric or other driving motor 18 together with its bearings and switch gear so as to exclude explosive gases, and a casing 25 enclosing the driving and feed gears. The drill spindle 17 carrying a drill 118 is screw-threaded to co-operate with a driven nut for feeding and is splined within a sleeve 29 rotatably mounted within a bearing bush 28 in a tubular part 27 of the casing 20. A gear 30 is secured to the sleeve 29 for driving the spindle and is rotated by a pinion 31 keyed to the motor shaft. The feed nut 34 is formed in two parts, each having a pair of lugs 55, Figs. 3 and 5, projecting radially from the rear ends thereof and pivoted on pins 60, 61 secured parallel to the axis of the spindle in a nut housing 40. Shoulders 57, 58 locate the nut axially in relation to the housing, and springs 69 tend to open the nut parts but are normally prevented from operating by a sleeve 65 having a spring detent 66 engaging a groove 67 at the end of the nut. To withdraw the spindle from the machine the sleeve 65 is removed from the nut which then opens. The housing 40 is keyed to a sleeve 33 rotatably supported in the casing 25 by ball bearings 35, 37. A bush 44 axially slidable on the sleeve 33 carries a gear 45 driven by a pinion 46 on the motor shaft, motion of the bush to the left in Fig. 3 causing a flange 50 thereon to engage a friction flange 41 integral with the sleeve to rotate the nut in the same direction as the spindle but at a higher speed, for feeding the drill, and motion to the right causing a flange 49 on the bush to engage a friction flange 42 keyed to the sleeve to hold the nut stationary for rapid withdrawal of the drill. The bush is moved axially and its rotation is prevented by a yoke 52, pivoted to the casing at 53 and pivoted at the lower end to trunnions on a nut 76 co-acting with a screw 78 carrying a hand-wheel 80. The motor 18 is stated to rotate at 3000 r.p.m. and the gears are such that the spindle 17 rotates at 600 r.p.m. and the nut 34 at 700 r.p.m. the pitch of the thread on the spindle being four threads per inch. When the hand-wheel 80 is operated to move the gear 45 to the left for feeding, the drill is thus advanced at a speed of 50 inches per minute, a spring 83, acting on a collar 82 on the screw 78, forming a yielding abutment to allow the clutch 41, 50 to slip and relieve the feed on overload. On rotating the screw 78 in the opposite direction the hand-wheel 80 has a rigid abutment on the casing 25 and the nut 34 is held stationary to withdraw the spindle at 150 inches per minute. A tubular casing 32 is attached to the part 27 to prevent injury by the spindle as it is retracted. Stands and supports.-A semicircular flange 84, Fig. 2, on the casing 20 is received within a similar flange 88 on a cradle 86 vertically adjustable on a pillar 87. A screw 89 actuated by a hand-wheel 92, screws into a boss 91 on the casing 20 to secure the parts together in adjusted position and serve as a pivot. The pillar 87 is provided with ratchet teeth 97, Fig. 1, with which co-operates a pawl 96 on a hand-lever 95, the pawl being normally pressed towards the ratchet by a spring 98. Locking of the cradle in the adjusted position is effected by a clamping bolt 102 and handle 103. The ends of the pillar are secured by bolts 105, 108 to arms 104, 107 for engaging the roof and floor respectively. The arms are both offset, as shown at 107 in Fig. 1, so as to balance the weight of the drill about the pillar. Adjustment of the length of the pillar is effected by a hollow plunger 110, Figs. 1 and 7, slidable in a boss 109 of the arm 107 and provided with ratchet teeth 144 co-operating with a pawl 143 on a hand-lever 142, normally engaged by a spring 145, a screw 148 and handle 149 being provided for locking. A screwed abutment 111 is slidably keyed at 115 inside the plunger and is adjusted axially by a hand-wheel nut 112 rotatably supported on the plunger by a spring pin 113 engaging a flange 114 thereon. To assemble the drill on the cradle, the pillar is inverted and the flanges 84, 88 placed together, whereupon rotation of the pillar, about the screw 89, into its proper position will engage the arcuate flanges. Sockets.-In one form of socket for attaching the drill 118, Fig. 3, to the spindle 17, the socket 116 is riveted at 117 to the spindle and has a rectangular recess to fit the shank of the drill, axial movement being prevented by a pin 121 passing through a groove 119 in the shank and holes 120 in the socket which are in partial register. Rotation of the pin causes a flat 122 thereon to come opposite the drill and allow its withdrawal. An alternative form of socket, which permits the feed screw to be removed readily from the associated parts, is described in Specification 382,887.