Patent GB-197652-A (GB)
Title: Improvements in or relating to apparatus for grinding or surfacing gear blanks
IPC: B23F5/02
Filed: 1922-05-30
Abstract: 197,652. Lees-Bradner Co., (Assignees of Schurr, C. H.). May 15, 1922, [Convention date]. Gear-cutting; mandrels.-In a machine for generating gear teeth by grinding, the rolling of the blank past the rack-tooth grinding-disc and the indexing of the blank are both effected through an oscillating member which is automatically disengaged from an indexing disc near the end of its movement and is subsequently re-engaged so as to bring a fresh tooth on the blank into contact with the tool. The work-spindle may be actuated to effect the rolling of the blank in the manner described in Specification 187,663 and the grinding-spindle may be mounted as described in Specification 197,631. The blank B is carried on a mandrel 64 which is supported in bearings on a carriage 61 and is formed in two parts to facilitate clamping of the blank. The section 64<b> is provided with a tapered end which is tightened in a conical seating formed in the section 64<a> by means of a bolt 66<a>. The outer end of the mandrel is supported by a centre 74 carried bv a slide 71 mounted on an arm 69 integral with the carriage 61. The arm 69 is provided with a rack 75 coacting with a hand-operated pinion for the axial adjustment of the centre 74, the slide 71 being locked by means of a wedge bar 77. The rolling and indexing of the blank are effected from a shaft 80 driven from a driving shaft 36 through the gear train shown in Fig. 12. Gears 143, 145 driven in opposite directions from a countershaft 133 are looselv mounted on a shaft 144 which through spiral gears 153 drives the shaft 80 carrying a worm 161 engaging a worm wheel 162 on a shaft carrying a disc having stops 166, 167 which coact with lever 168, Fig. 10, connected to a sliding clutch-member on the shaft 144. By means of this mechanism the rotation of the shaft 80 is reversed after a predetermined number of revolutions, the gear 153 being slidable against springs to cushion the reversal. Further means are provided for the hand adjustment of the shaft 80 and for stopping the shaft by a clutch operated from a hand lever. The oscillation of the shaft 80 is transmitted through a worm 89 engaging a sector 91 secured to a disc 93 on a sleeve 65 surrounding the blank mandrel. Rolling of the blank is effected by flexible-band mechanism comprising four alternately arranged tapes 96, 96<a> secured through pivoted tensioning devices to a shoe member 105 and passing round a sector 95 surrounding the blank mandrel and of the same diameter as the blank pitch-circle. The construction is such that the mandrel 64 may be rotated relatively to the sleeve 65 and sector 95 to index the blank. The tapes extend round a clamping plate 102 and their free ends are clamped by a bar 104 secured by screws. The position of the member 105 may be adjusted by a screw 121 and the support 115 for the band mechanism may be adjusted according to the size of the blank by a screw operated from a handle 130. To index the blank between successive rolling operations a block 184, secured to the disc 93 is provided with radial guides accommodating a plunger 187 coacting with recesses 189 in a plate 190 secured to the blank mandrel, the number of recesses being equal to the number of teeth in the blank. When the plunger 187 is in a recess 189 the disc and plate 190 are connected together so that the oscillations of the shaft 80 are transmitted to the blank mandrel and through the band mechanism the carriage 61 is traversed to roll the blank past the cutter. At the end of the clockwise movement of the plate 190 the tool moves out of engagement with the blank and the latter is in. dexed by means of trip mechanism 198 which automatically disengages the plunger from its notch and locks the plate 190 so that on continued movement of the disc 93 the plunger moves into engagement with the next succeeding notch. Further means are provided for positively preventing the disengagement of the plunger from its notch during the grinding operation. The main driving belt for the shaft 36 may be shifted by rack and pinion mechanism operated from a hand crank 258.