Patent GB-284495-A (GB)
Title: Improvements in or relating to metal cutting machine tools
IPC: B23B39/16
Filed: 1927-03-23
Abstract: 284,495. Imray, O. Y., (National Automatic Tool Co.). March 23, 1927. Drilling-machines; tapping.-In a machine for cutting screw-threads or similar helices, a lost motion device is incorporated in either the spindle rotating mechanism or the feed mechanism so that on reversal of both, the action of one of them will be delayed until the backlash in the gearing of the other has been taken up. In a multiplespindle machine having a power feed 192a for drilling and a hand feed 197 for tapping, the spindles 190, Fig. 1, are mounted in a head 188 vertically adjustable on a pillar 186 and are driven simultaneously from a shaft 191 through a lost-motion coupling 192 so that when the shaft 191 is reversed the rotation of the tools will not be reversed until sufficient time has elapsed for the feed to be reversed by means of the hand wheel 197. A multiple-spindle machine having a power feed for both drilling and tapping comprises a pillar 2, Fig. 3, having vertical guides 4 on which is slidable a tool-head 3 carrying spindles 6 driven from a shaft 7 through a lostmotion coupling 8. A rod 114 attached to the head carries dogs 112, 113 for operating, at opposite ends of each vertical traverse, a controller 110 for an electric motor 10 and so reversing both the feed and rotation of the spindles. The lostmotion coupling comprises a disc 129, Fig. 11, attached to the shaft 7, having a projecting lug 141 lying in the path of a lug 140 on a disc 127 rotatably mounted or the hub of a plate 120. A second lug 139 on the disc 127 lies in the path of a lug 137 on a second disc 128, also freely rotatable on the hub of the plate 120 and having a lug 136 lying in the path of a lug 135 on the plate 120, the latter being secured to a shaft 121 which drives the tool-spindles. On reversal of the rotation of the shaft 7, the tool-spindles will come to rest and will not be reversed until the shaft 7 has made three revolutions less the width of three of the lugs 140 &c. The amount of lostmotion provided may be varied by varying the number of discs or the thickness of the lugs. A casing 131 is attached to the plate 120 and is provided with an aperture for the injection of a lubricant such as light grease or heavy oil. If reversal of the machine is effected by a dog clutch instead of by reversal of the motor, cushioning means are incorporated in the lost-motion coupling comprising helical springs inserted between the engaging faces of the lugs. Driving machine-spindle.-The shaft 7 is driven through a train of gears in a casing supported by a bracket 16, Fig. 3, on the head 3 from a vertical splined shaft 11 which is rotated through bevel gears 29, 33, 36, Fig. 5, a shaft 37 and spur gears 40 from the electric motor 10. Feed-motions; speed-controlling mechanism.- The tool-head 3 is fed vertically by a rack 52, Figs. 3 and 8, engaged by a gear 25 meshing with an elongated pinion 51 on a shaft 50 carrying a gear 49 driven from a worm wheel 42, the latter being driven by a worm 41 splined on a vertical shaft 12 rotated through bevel gearing 28, 59, 64, Fig. 5, frcm a shaft 63 which receives is rotation through a differential gear 66 from the motor 10. The shaft 63 which carries the bevel gear 64 has rotatably mounted thereon two combined spur and bevel gears 67, 68, and fixedly mounted thereon a casing carrying rotatably mounted bevel gears 71, 72. The gear 67 is driven continuously in either direction by a spur gear 75 keyed to a shaft 76 having a wheel 103 thereon rotated through the shaft 37 from the motor, while the gear 68 is either maintained stationary (for giving a rapid traverse of the toolhead to and from the work) or rotated in the opposite direction to the wheel 67 at a slightly different speed (for giving a slow cutting feed) by means of an idler gear 78, a gear wheel 77 and a clutch 82. The clutch comprises a part 84 keyed to the shaft 76 and a part 81 slidable on the shaft 76 and splined to the wheel 77. An annular recess 88 on the clutch part 81 is engaged by a roller on the end of a lever 89, pivoted at 86 and having a roller 91 at the other end acted upon by a collar 92, Figs. 5 and 10, slidable on a shaft 93 and moved through springs 97 by a yoke 94. The yoke 94 may be reciprocated manually or automatically to operate the clutch 82 and control the speed of the tool-head traverse. Hand operation is by means of a handle 160, Fig. 3, a bell crank lever 102, Figs. 5 and 10, a link 101, bell crank lever 99 and link 98 connected at 95, to the yoke. The clutch is controlled automatically by a lug 162, Fig. 3, attached to the tool-head which engages a yielding abutment 163 on a rod 161 vertically slidable on the pillar 2 and provided with a rack engaging a spur gear 165, Fig. 10, connected by shaft 166 to a gear 167 engaging a rack on the link 98. The gear 68 is maintained stationary by lugs 105, 106 on the clutch part 81 which are brought into line with a projection on the casing 38, Fig. 5, when the clutch is moved to the left but are moved clear of the projection when the parts 81, 84 are engaged. Adjustment of the tool-head by hand may be performed by moving the shaft 50, Fig. 8, axially and disengaging the gear wheels 48, 49, whereupon the pinion 51 may be rotated by the hand-wheel 53. A spring 54 maintains the wheels 48, 49 normally in engagement. Balancing parts.-The tool-head 3 is balanced by a counterweight (not shown) connected by cables 26, Fig. 3, passing over pulleys 27 at the top of the pillar 2.