Patent GB-188722-A (GB)
Title: Machine for cutting gears and other toothed, grooved or polygonal articles
IPC: B23F1/04
Filed: 1921-07-15
Abstract: 188,722. Stevenson, G. E. July 15, 1921. Gear-cutting.-In a machine for cutting gears &c. the teeth are all cut simultaneously by a series of circumferentially arranged and radially fed cutters mounted in a tool head, and the cutter .clamping mechanism is automatically released at each stroke of the reciprocating blank mandrel to allow the radial feed of the cutters and relief on the idle stroke to be effected. The driving wheel 30 driven through gearing from a suitable motor is connected by links to an eccentrically mounted shaft 21 which is thus driven at a variable speed and which transmits motion through a crank 22 and connecting-rod 35 to a pin 36 adjustably secured to a blank carrying ram 39. The crank is provided with a scale 22<1> for adjusting the stroke of the ram. The tool-carrying head 62 carries a ball-bearing ring 63 provided with a series of circumferential cam surfaces 68 against which the outer ends of the tools 69 abut. Each cam is further provided with a retracting cam surface 70 engaged by a pin 71 carried by the tool. The tools are accurately seated in radial grooves in a ring 72 and are secured by a ring clamped by nuts 79 on bolts 78 passing through both rings. Each of the nuts 78 is locked to an arm 80 adjustable on a pivoted toothed sector 81 engaging internal teeth on a gear ring 84 which is intermittently reciprocated by means of a sector 87 actuated through lever mechanism from a cam 93 on the main driving gear 30 in order to release and tighten automatically the clamping ring 75 relatively to the tools 69. A modified arrangement of the tool clamping mechanism is also described. The tools are intermittently advanced towards the blank by means of a toothed. portion 64 on the cam ring actuated through spur gears 95, sector 97 and lever 99 from the feed cam 101 which is intermittently rotated by ratchet mechanism operated by gearing interconnected with the cutter clamping and releasing mechanism as shown in Fig. 7. The withdrawal of the tools during the return stroke is effected by means of a second cam 108 on the wheel 30 acting through suitable lever mechanism to swing the segment 97 in a direction opposite to the feeding movement. Cutting is effected during the up-stroke of the tool ram. In order to minimise errors in the product due to differences in the tools 69 the blank is indexed so that each tooth is acted upon by each tool in succession. Preferably the tool head may consist of roughing and finishing cutters arranged alternately round the head. The lower end of the spindle 51 carries a semi-cylindrical cross, head 130 slidable in a sleeve 131 carrving a worm wheel 134 driven by a worm actuated through a change gear train by Geneva mechanism 140 driven from a shaft 148. In order to cut compound gears having indefinite staggered positions, the indexing worm may be provided with a fine angular adjustment. To increase the power delivered by the Geneva mechanism the worm wheel 134 may carry a spur gear 180 engaging a wheel 181 on a sleeve 182 connected to a constantly driven shaft 184 through a spring 188 the arrangement being such that as soon as the Geneva mechanism is released the power stored in the spring 188 acts through the gears 181, 182 to assist in moving the spindle 51. Sheet metal housings 191, 192 may be provided for protecting the ram guide from chips &c., the housing 191 being supplemented on one side by a semiannular pan 196 from which the cuttings may be washed by oil or other cooling liquid. Sockets.-The ram 39 carries at its upper end a head 47 adapted to receive the tapered shank of mandrel 49 carrying one or more blanks 50, and secured to the spindle 51 journaled in the ram. An ejector 121 may be actuated from a pedal 124 to remove the mandrel from its seating.