Patent GB-184530-A (GB)
Title: Improvements in apparatus for producing toothed gearing
IPC: B23F5/02
Filed: 1921-04-06
Abstract: 184,530. Kitchen, H. E. April 6, 1921. Gear-wheels, grinding and trueing teeth of.-The teeth of gear-wheels are formed by a grinding-disc or by a cutter, which moves tangentially to and in unison with a rotating wheel-blank until the effective position has been passed, the cutter then being withdrawn from the blank and returned at a higher speed to a position slightly beyond the original position. The blank is simultaneously returned at a different, but also higher, speed, so that at the end of the return stroke it occupies a position displaced from its original position by slightly more than one or more pitches; by this arrangement, backlash is taken up and the cutter accurately engages, on the next working stroke, another tooth space. The quick return is brought about by acceleration of the main driving-shaft of the machine, and the reversal of the direction of the tool and the blank is effected through clutch mechanism and cam-gear. On the main driving- shaft c is keyed a sliding clutch d, whereby either of two gears e, f may be rotatively connected to the shaft. On a shaft g, which drives the blank, adapted to be engaged by a corresponding surface is secured a gear h having a clutch-surface on a sleeve i loosely mounted on the shaft and carrying a gear j, and similarly mounted on a shaft k, which drives through change-gearing e a screw m for giving the tangential movement to the cutter, are a gear n and a clutch sleeve o carrying a gear p. Thus, when the clutch i engages the gear h, the clutch o is disengaged from the gear n, and vice versa, the movements of the sleeves being brought about by a collar d<1> on the clutch d. The gear n meshes with the gears e, j and the gear h meshes with the gears f, p, the forward drive being given when the clutch d engages with the gear f and the reverse when the clutch engages with the gear e. The shaft c drives through a worm t<1> a worm-wheel t, which makes one complete revolution for each cycle of operations of the machine, and on the shaft of the worm-wheel are two cams s, s<1>. The movement of the clutch d to effect reversal of the machine is brought about by an angle-lever r, which engages a circumferential cam-slot d<2> in the clutch and oscillates until it is arrested by one of the cams, further rotation of the clutch then causing axial movement thereof to effect the reversal. At about the time that the lever r is held stationary, a partly-toothed wheel u connected to the worm-wheel engages a toothedwheel v, which operates mechanism to remove the cutter clear of the blank. The quick-return movement of the cutter and blank is effected by acceleration of the shaft c, which is driven bv a toothed wheel x and a pawl y and ratchet z. The acceleration is given by a belt-driven shaft 3 through bevel-gears 1, 2, the shaft 3 having thereon fast and loose pulleys 4, 5, and the belt being moved at the correct intervals by a shifter 6 operated, through a lever 7, by an adjustable cam 9 carried by the shaft of the worm-wheel t. In place of a single cutter, a number of cutters may be used, which operate simultaneously. The grinding-wheel b is rectified at the end of each cycle by a rectifying-device 10, Fig. 6, the shaft b' of the grinding-wheel being mounted eccentrically in a disc 11 having fast therewith a wormwheel 12 meshing with a worm 13, which is partly rotated at the end of each cycle by a ratchet and pawl 14, 15. The eccentric movement of the wheel moves it into the rectifying- device and also moves it forwards through the same distance towards the blank; the disc 11 is re-set when necessary. According to the Provisional Specification, the acceleration of the driving-shaft is produced by a sliding sleeve, which can be clutched to and declutched from a gear running freely and at high speed on the shaft, the clutch being operated by a conical cam attached to the worm-wheel t; the machine may be employed to produce helical gears as well as ordinary spur-gears.