Patent GB-1384837-A (GB)
Title: Cam grinding machine
IPC: B24B17/02
Filed: 1973-04-27
Abstract: 1384837 Grinding cams TOYODAKOKI KK 27 April 1973 [15 May 1972] 20278/73 Heading B3D A cam grinding machine comprises a machine cam 6 which is axially aligned with a workpiece W for rotation therewith and urged against a roller 30 to control the grinding of the workpiece by a grinding wheel 11, the roller 30 and a second smaller roller 31 being mounted on a supporting means 28 movable to engage the second roller with the master cam when the diameter of the grinding wheel is reduced to a predetermined size. The workpiece W is mounted between a tailstock 10 and a spindle 7 supported. by bearing 8, 9 on a swing table 4 carrying the tailstock. The swing table is mounted on a shaft 5 supported by bearings 3 on a table 3 transversable on a bed 1. The master cam 6 is mounted on spindle 7 and a spring 25, adjustable by a screw 24, acts on the table 4 to press the cam against the roller 30 or 31. The spindle 7 has a brake drum 12 and is connected by universal joints 13, 20 and a spline 21 to a shaft 19 driven by reduction gearing 16, 17 from a motor 15. The roller 30 is mounted on a supporting shaft 29 which has an eccentric portion supporting the roller 31. The axial spacing or pitch between portions of the master cam is 1P whereas the axial spacing of the rollers 30, 31 is 1À5P. The shaft 29 is mounted on a carriage 28 movable along guideways 27 on the bed 1 by rotation of a pinion 33 engaging a rack 32. The pinion 33 meshes with a gear 34 on a shaft 35 on which is slidably mounted a double gear 36 having two stars wheels 39, 40, the teeth of which are staggered by half a pitch. The double gear 36 is axially slidable by a fork 45 movable by a piston 43 in a cylinder 42 so that one or other of the star wheels 39, 40 is engageable with dogs'38 in a bar 37 fixed to a part 1a of the machine bed 1. The star wheel 39 or 40 engaging the dogs 38 is rotatable by a pawl 50 actuated by a piston 47 in a cylinder 46. In operation, the traverse table 2 is indexed so that the cams on the workpiece are ground by the wheel 11, the carriage 28 also being indexed at the same time, so that the roller 30 engages successive portions of the master cam, by the dog 38 engaging the star wheel 39 to rotate pinion 33 and move the carriage the pitch 1P of the portions of the master cam. When the grinding wheel has been reduced to a predetermined diameter following dressing, the table 2 is returned to its initial position and the piston 43 is actuated to cause the star wheel 40 to be aligned with the dogs and, because of the half pitch difference between the star wheels, when the table is initially indexed, the star wheel 40 rotates through a distance of 1¢ times its pitch to cause the support 28 to move through a distance of 1¢P to align the small roller 31 with the master cam, successive indexing movements 'of the table moving the support through distances of 1P. When the grinding wheel has worn and is replaced by a new wheel, the piston 43 is actuated to re-engage the star wheel 39 with the dogs 38 and the piston 47 moves the pawl 50 so that the star wheels are rotated to return the carriage 28 to its initial position. The change over from the large to the small roller may be effected when the grinding wheel radius is reduced by wear or dressing and its size is indicated by a counter or limit switch.