Patent GB-780090-A (GB)
Title: Improvements in or relating to the forming or dressing of grinding wheels
IPC: B24B53/08
Filed: 1955-01-26
Abstract: 780,090. Dressing grinding wheels. CIMATOOL CORPORATION. Jan. 26,1955 [Feb. 4, 1954], No. 2339/55. Class 60. An apparatus for dressing a grinding wheel 25, Fig. 3, comprises a dressing tool 22, means supporting the tool for movement in the dressing operation, means for directing the tool in predetermined paths during progress of the tool in one direction and its return in the reverse direction, the directing means comprising first and second actuating means operatively connected to the dressing tool and co-operating to control the path of movement of the dressing tool, drive means operatively connected to the first and second actuating means, means in the drive means changing the timed relationship between the first and second actuating means upon each change in direction of tool progress, and means for adjusting the amount of change in the timed relationship as required for forming operations. The wheel 25, Fig. 14, may be a ribbed wheel for grinding screw threads and a diamond 22 dresses one side of the ribs during traverse in one direction and the opposite side of the ribs during traverse in the return direction. The diamond is carried by a transversely displaceable carriage 23 mounted in roller ways 40, 41, Fig. 5, in a slide 20 which is longitudinally displaceable by a lead screw 90 co-operating with a split nut 100, Fig. 8, which is attached to the base 21 of the apparatus and loaded by springs to prevent back lash. During traverse in one direction the transverse movement of the slide 23 is produced by a cam 55, Fig. 11, while in the return direction it is produced by a cam 56, the changeover being effected by a pair of followers 61 mounted at different heights on a vertically displaceable member 57 connected to a piston 67 which is operated automatically each time the slide 20 is reversed. The cams 55 and 56 are secured to a shaft 54 driven by worm gear 47, 52 from a flexible shaft 46 connected to a reversible electric motor. The shaft 54 also drives through gearing 84, 85, 87 and 88 to lead screw 90, the gears 85, 87 being carrried by a lever to enable the drive ratio between the shaft 54 and the lead screw 90 to be changed. To prevent the lost motion in the drive to the lead screw 90 from disturbing the timed relationship between the longitudinal and transverse movements, the lead screw 90 is arranged to have additional lost motion which may be adjusted by screw-threaded adjustment of a stop 106 carried by the slide 20 and enables the cams 55, 56 to complete an integral number of idle revolutions on each reversal of the slide. An indicator plate 80 and dial gauge (not.shown) are used to provide the required amount of lost motion when the machine is set-up for a dressing operation. During traverse to the right of the slide 20, Fig. 5, the screw 90 engages the stop 107 and disengages the stop 106, the stops being air loaded when they are operative and the air connection being changed on each reversal of the slide 20. Two switches 130 and 131 operated by adjustable dogs 134 and 135 reverse the motor driving the flexible shaft 46 and operate relays controlling the fluid supply to the piston 67 and the stops 106 and 107. A flexible boot 78, Fig. 5, permits reciprocation of the slide 23 while preventing the ingress of foreign matter to the dressing mechanism.