Patent GB-512341-A (GB)
Title: Improvements in or relating to drilling and analogous machines
IPC: B23B47/18
Filed: 1938-04-19
Abstract: 512,341. Drilling. JONES & SHIPMAN, Ltd., A. A., and WILKINSON, J. H. April 19, 1938, No. 11727. [Class 83 (iii)] In a drilling &c. machine wherein the feed is derived from a rotary shaft, the shaft carries a part rotating adjacent a fixed part and forming therewith an annular space containing a freely floating element, each of the parts being provided with a projection extending into the annular space and capable of passing each other except when the floating element is brought between them by rotation of the shaft in the feedng direction. The feeding shaft 1, Fig. 1, rotatable by means of a hand lever 6 or a power drive, carries a pinion 3 engaging a quill 5 on the drill spindle. The stationary bearing 2 for the shaft has a stepped surface forming an annular recess e together with a flange 13 mounted on a disc 17 keyed at 19 to the shaft, the floating element consisting of a ball 21 freely movable in the recess. A pin 9 projects partly from the periphery of the bearing 2 and a pin 11 projects inwardly from the flange 13 so that with the parts in the positions shown in Fig. 2, with the ball 21 between the pins and the drill spindle in its uppermost position, the flange cannot rotate in the direction of feeding, shown by the arrow A in Fig. 2. By releasing a nut 26 on the pin 11 a notch 23 in the pin ceases to grip the disc 17 and the flange 13 may then be rotated rearwardly, with regard to the direction of feed, to space the pin 11 away from the pin 9 by an amount equal to the rotation of the disc for the required amount of feed. The flange may then be secured to the disc again by means of the nut 26 and the spindle can then be fed until the pin 11 brings the ball 21 into contact with the pin 9 again to stop the feed. The maximum adjustment of the flange is nearly two revolutions since the ball may lie at the bottom of the recess e and allow the pin 11 to pass round to its other side during adjustment. The flange 13 may be graduated on its face or periphery with a scale of feeds, and micrometer adjustment may be provided for either or both of the pins. The pins may project radially into the recess e instead of axially. For stopping a power feed a power-driven worm wheel 28, Fig. 7, is freely rotatable on the boss of a pawl carrier 34 which is keyed to the pinion shaft 1 and carries a pivoted pawl 31 rocked by a spring 33 to engage a ratchet wheel 30 secured to the worm wheel. A tail 32 on the pawl 31 lies in a recess 35 in 'the disc 17 so that during a power feed the worm wheel 28, ratchet 30, carrier 34, shaft 1, flange 13 and pin 11 rotate together until the pin 11 brings the ball 21 against the stationary pin 9, thereby stopping rotation of the disc 17 and causing the side of the recess 35 therein to rock the pawl 31 out of contact with the ratchet 30 to disconnect the worm wheel from the shaft 1. The hand feed levers 6 are attached to a boss of the disc 17, which in this case is not keyed to 'the shaft 1, and a peg 37 on the disc engages a short slot 38 in the carrier 34 to impart hand feed to the shaft within the limits of the stop mechanism, the pawl then over riding the ratchet.