Patent GB-558982-A (GB)
Title: Improvements relating to machines for forming machine elements such as gears
IPC: B23F5/20
Filed: 1941-11-20
Abstract: 558,982. Gear-cutting. MICHIGAN TOOL CO. Nov. 20, 1941, No. 14961. Convention date, Oct. 29, 1940. [Class 83 (iii)] A machine for form-cutting simultaneously all the teeth in a gear or like machine part particularly helical gears of involute form has the work mounted on a reciprocating holder while the cutters are mounted radially in a head and are fed gradually into the work and relieved therefrom on the return strokes of the work holder. The vertical machine frame 10 carries a vertically-adjustable cutter-slide 14, adjustment being effected by a screw 18. The work blank 32 is mounted against a shoulder 36 on a mandrel 34 which has a grooved upper portion to allow cutting lubricant to flow from a pipe 144 to the working point. Spacers are located between the bottom of the blank and a plate 44 secured between collars on the mandrel. The plate 44 is secured to a rotatable ram slidable in a sleeve 52 over which is located a sliding chip guard 60. A stem 62 on the ram terminates in a ball member 64 mounted in a secondary ram 70 which is reciprocated by a crankshaft 86 driven from a motor 96 through gearing 94. The stem 62 is associated with guide means for imparting the required twisting movement to the blank. For this purpose a spiral guide 101 fixed to the stem has a helical guide surface 104 coacting with complementary guides, fixed to the sleeve 52. The cutters 116 are radially mounted in spaced slots 126 in a head 128. Each cutter is of right angled trapezoid section and the slots are inclined as shown in Fig. 7 at approximately the helical angle of the gear teeth. The cutting edges are of the required involute tooth form. The outer ends of the cutters are shaped to conform to a conical member 166 and inclined slots in the cutters are engaged by a conical ring member 182 secured to the member 166. The bottom plate 132 which returns the cutters is secured to an extension 138 of the slide 14. The slide is also formed with a part 146 carrying a headretaining tube 144 which has a flexible connection 148 to a lubricant pump 152 driven by a motor 156. A supporting member 160 bolted to the part 146 is radially slotted on its under surface and interlocks with the cutter head to prevent rotation thereof. In order to feed the cutters to the work the conical member 166 is secured by nuts 176 to a feed member 174 and has a vertical movement guided by adjustable bearing pieces 184. The upper part of the member 174 terminates in a part 190 slidable in a feed plate 192 which is itself slidable on the slide 14. The plate 192 is moved downwardly in timed relation to the ram movements to feed the cutters radially inwards while the plate 190 is moved upwardly alternately with the down feed of plate 192 to relieve the cutters from the work on the non- cutting strokes of the work ram. For these purposes a cam shaft mounted in the member 192 carries a cam fed by a ratchet wheel 204 and arranged to make one revolution to complete the radial feed of the tools. The cam engages a follower secured to the carrier 14 and the member 192 is urged upwardly by springs 220. The ratchet wheel is engaged by a pawl on a rod 228. The relieving movement is produced by a cam rod 232 engaging rolls 234 on the member 190. A cross-head 226 is connected through a link 242 and other lever mechanism to the crank shaft 86. Thus at each stroke the cam is rotated one step to feed the tools gradually to the work while at the end of the cutting stroke the cam rod 232 withdraws the tools. The parts 190, 192 are locked together with the tools in cutting position during the operative strokes by a pin on the cross-head.