Patent GB-355475-A (GB)
Title: Improvements in or relating to cam grinding machines
IPC: B24B19/12
Filed: 1930-07-30
Abstract: 355,475. Grinding. LANDIS TOOL CO., Waynesboro, Pennsylvania, U.S.A.-(Assignees of Steiner, A. P. ; Wine, E. P.; Ott, C. L. ; and Balsiger, H. E. ; of Landis Tool Co., Waynesboro, Pennsylvania, U.S.A.) July 30, 1930, No. 22935. Convention date, Aug. 7, 1929. [Class 60.] Disc apparatus.-An automatic machine for grinding cams on camshafts consists of a bed 10 carrying a work carriage 11 and a wheel base 12 supporting a grinding-wheel 13. On the carriage is pivoted a cradle 18 for supporting the work, which is mounted on a tailstock and a headstock 15 on the cradle, and the cradle is swung to and from the grinding-wheel, to give the required profile to the cams, under control of master cams 19 mounted in the headstock and adapted to engage a roll 20, which is movable opposite to the required cam by a screw 22. The screw is rotated to move the roll 20 by means of chain gearing 38, 34 from a shaft 33 movable with the carriage and driven through bevel gearing and a pinion from a rack 24 attached to a bracket 26, to which also is connected a piston-rod 25. This rod is connected to a piston 27 movable in a cylinder 28 carried by the bed and serving to move the carriage. The cradle is held with the master cam against the roll 20 by a spring 38, and the cams may be moved away from and up to the roll 20 so as also to carry the work away from the wheel 13 when the work is to be moved to position the next cam, and again into operative position, by a piston 47 in a cylinder 44 having inlets 52, 53 ; a ball valve 52<1> with a byepass 50<1> prevents too sudden a return of the cams to operative position. The timing mechanism includes two connected cams 54, 55 for hydraulic and electric control respectively. The cam 55 operates a limit switch 56 in the circuit of the motor driving the work, and on being closed causes the insertion of a resistance in parallel with another resistance in the field circuit of the motor, thereby slowing down the motor for finish grinding. The cams are carried by a shaft 71 driven through gearing by a motor 72 and the cam 54 engages a follower 75 on a lever 74 pivoted at 77 on the bed. The end of the lever carries a finger 78 adapted to engage notches 80 in a spacing bar 79 corresponding to the spacing of the cams on the shaft. On the base 10 is a valve casing 81 containing valves 82, 83 the valve 82 being a reversing valve for causing operation of the piston 47 and of a piston 86 which feeds the wheel up to the work and withdraws it therefrom ; a regulator 121 is provided to slow down the movement of the wheel base just before the wheel engages the work. When the cam 54 moves so that its point 76 lifts the lever 74, the finger 78 is withdrawn from the slot in the bar 79 and the valve 82 is depressed against the action of a spring 92 causing reversal of the fluid pressure supply to the pistons 47, 86 and causing downwards movement, through a lever 97, of a valve 83 to allow fluid to pass to the cylinder 28 and thereby move the carriage to bring the next cam into position for operation thereon ; during grinding, with the valve 83 depressed, no movement of the piston 27 can take place, since fluid supply-is cut off from the cylinder 28. When the valve 83 is raised, the movements of the table depend upon the position of a reversing lever 106 engaged by dogs on the carriage, and which may be set to move the carriage in either direction. The rotation of cams 54, 55 is stopped at the ends of the strokes of the carriage by a clutch 117 operated, through levers 110, 115, by a cam on the spacing bar 79. In operation, the carriage is at the extreme right-hand position, the grinding-wheel is retracted and the cam 19 is retracted from the roll 20. With a shaft in position, the lever 106 is thrown to the right, causing the carriage to move to the left allowing the clutch 117 to engage and the finger 78 to enter the first notch of the bar 79. This, by means of the valves, stops the carriage, engages the cam 19 and the roll 20 advances the grinding- wheel, the work rotation being slowed down for finish grinding. The cam 54 then lifts the lever 74 and the process is repeated on the next cam.