Patent GB-292612-A (GB)
Title: Improvement in drilling tools
IPC: E21C25/66
Filed: 1928-06-22
Abstract: 292,612. Sullivan machinery Co., (Assignees of Holmes, M. P.). June 23, 1927, [Convention date]. Drilling. - machines. - In a rotary drilling- machine particularly adapted for drilling shot holes in coal or other mines, the drill is universally adjustable relatively to a support which carrries the driving motor and an automatic power feed is provided which withdraws the drill intermittently if an unduly hard obstruction is encountered until the obstruction has been penetrated. The driving and feed mechanisms for the drill comprise friction clutches which are both rotated by the motor to provide the cutting feed, while either clutch may be disconnected alternatively to provide more rapid feed in the same or in the opposite direction to the cutting feed. The drilling-machine is attached to a coalcutting machine, preferably that described in Specification 277,994, [Class 68 (i), Excavating earth &c.], which comprises a body 4, Fig. 15, mounted on wheels 5 running on rails 6 and carrying a head 7 which supports a cutter-bar 8. The drill 124 is secured in a chuck 113 attached to the end of a hollow shaft 78 rotatably mounted in a head 62 rotatable about an axis 58 on a bracket 50 carried by a tubular support 49 which is rotatable about its axis in a bracket 52. The latter is rotatable about a horizontal axis 53 and is supported by a bracket 20 rotatably on the machine about a vertical axis. The driving gear for the drill passes through the hollow support 49. The shaft 9, Fig. 2, of the reversible electric motor which drives the coal-cutter carries a pinion 10 which drives both the rotating and feeding gearing for the drill through bevel gearing 15 and a clutch sleeve 29 engaging the splined ends of two coaxial shafts 18, 26. The clutch is controlled by a pivoted yoke 30 carrying a slotted arm engaged by an eccentric pin on the end of a shaft hand operated by a lever 38, Fig. 15. The shaft 26 rotates a bevel gear 41 engaging a pinion 44 on the end of a shaft 46 which passes through the hollow support 49 and carries at its other end a pinion 56, Fig. 10, which drives a bevel gear secured to a spindle 58. A second similar bevel gear secured to the opposite end of the spindle 58 engages a pinion 64 on a shaft 65 which carries two spur gears 67, 68, the former having a larger number of teeth than the latter. The gear 67 drives the drill shaft 78 through a pinion 69 keyed to a sleeve 72 carrying one set of friction clutch elements 73, the intervening elements being carried by a sleeve 75 splined on the shaft 78. The gear 68 meshes with a gear 70 which rotates a sleeve 87 through a similar friction clutch 82, a long feed screw 89 being secured at 88 to the sleeve and engaging a nut 91 formed integral with the drill shaft 78. The friction clutches are normally closed by springs 101, 105, but may be opened by collars 99, 103 respectively, operated by yokes 106, 107. The shafts 106' on which the yokes are mounted each carry a lever, the two levers pointing towards each other and their adjacent ends engaging in slots in a sleeve which may be oscillated by a hand lever so as to disengage either clutch separately. The head E is locked in its adjusted angular position relatively to the bracket 50 by means of a slotted sector 149 on the head and a hand-operated screw on the bracket. The support 49 is axially rotatable in the bracket 52 by means of a worm-whee 156, Fig. 2, on the support and a hand-operated worm 159 which is selflocking. Rotation of the support 49 about the horizontal axis 53 is effected by a link 133 pivoted at 132 to the bracket 52 and at 134 to a pair of gudgeon pins on a block 135 which is screwthreaded to engage a screw 140 and is slidable between guides 136 on an extension 137 of the bracket 20. A reversible ratchet lever 146 is provided for rotating the screw 140 by hand. The bracket 20 is rotatable about the vertical axis of the shaft 18 by hand and runs on rollers 21 in a guide-way formed by a cover-plate 24. In operation, the machine is moved up to the coal face and an undercut is formed by means of the cutter bar 8, after which the drive to the cutter bar is stopped and the clutch 29 is operated to rotate the drill. The drill clutch lever is then operated to open the feed clutch 82, whereupon the feed screw 89 remains stationary and the drill is fed rapidly towards the coal face due to the rotation of the nut 91 with the drill shaft. On encountering the work the clutch lever is released and both clutches are then in operation to rotate the feed screw and nut in the same direction at slightly different speeds so as to impart a cutting feed to the drill. Should the drill encounter an unduly hard substance the driving clutch 73 will slip and allow the drill to cease rotating, whereupon the feed screw will continue to rotate relatively to the nut and withdraw the drill until it can again rotate, the retraction and advancing of the drill continuing intermittently until the obstruction has been pierced. When the drill has penetrated to the required depth the clutch lever is operated to open the driving clutch 73 and the drill ceases to rotate and is withdrawn rapidly. The shafts and gearing are mounted in the ball bearings shown and packed glands 95, 96, Fig. 10, are provided for retaining oil in the head 62. Sockets.-The shank of the drill 124, which is formed with a squared end 123 and a reduced neck 126, is inserted in a bush 117, Fig. 12, having a square bore and a cylindrical exterior. Dogs 118 on the bush engage projections on a dog 119 keyed to the chuck body 114 at 120, the arrangement being such that rotation between the bush and body may take place to allow the shank to be withdrawn through a squared opening 125 in the body.