GB1094097A - Improvements in and relating to grinding machines - Google Patents

Abstract

1,094,097. Grinding cams. LANDIS TOOL CO. Dec. 18, 1964 [Dec. 20, 1963], No. 51503/64 Heading B3D. A cam grinding machine comprises a work carriage 22, a cradle 20 on the carriage for rocking movement toward and from a grinding wheel 12, a master cam 18 and means 15, 16 for rotatably supporting a cam shaft W to be ground on the cradle, a follower 30 opposite the master cam, pressure means 60, 80 for applying a predetermined force for holding the follower and cam in contact, and means automatically operable to change the pressure exerted during a grinding operation. The grinding wheel is mounted on a support 11 adjacent a work table 22 longitudinally movable to place successive cams on the cam-shaft W in alignment with the grinding wheel. The cam-shaft to be ground is mounted between a headstock 16 and a tailstock 15 on the cradle 20 which is rockable on the work-table to move the camshaft W radially of the grinding wheel under the control of the master cam 18 on the cradle and the follower 30. The follower 30 is rotatable on a shaft 31 and is movable along the shaft in timed relation to the movement of the worktable to align the follower with successive master cams corresponding to the cams to be ground on the work-piece. The master cams and camshaft W to be ground are driven by a motor 40 and moved into and out of engagement with the follower and grinding wheel, respectively, by a piston 50 which is slidable in a cylinder 51 and connected by a rod 52 to one end of a sleeve 53, the other end of which has an adjustable abutment 62 for a spring 60. The latter engages a washer 65 through which extends a rod 66 at one end having a head 67 in engagement with the end position 75 of a lever 70 secured to the cradle 20 and passing through an opening 73 in the sleeve and at the other end having a spherical end portion slidable in a bore 68 in the abutment. During rough grinding, the end portion 75 of arm 72 is also acted on by a member 81 engaged by a spring 80, the other end of which is secured to an abutment 82 carried by a rod 96 of a piston- and-cylinder device 95. A bar 85 is pivotally connected to the abutment and has a slot 91 engaged by a pin 90 extending from the member 81. During finish grinding, the abutment 82 is retracted so that the spring 80 is not operative and only the spring 60 acts to press the master cam and cam-shaft W against the follower and grinding wheel. The operation of the machine is controlled by an electrical relay system operating on solenoid controlled valves for the cylinders of the machine. Upon initiating a grinding cycle a switch is closed which operates the circuit so that fluid pressure is supplied to the rod end of cylinder 51 so that the sleeve 53 is moved to cause spring 60 to act on lever 70 to urge the master cam 18 against the follower 30. At the same time, fluid pressure is supplied to the head end of cylinder 95 so that spring 80 also acts on the lever. Also fluid pressure is supplied to a further piston cylinder device which acts through a rack-and-pinion to advance the grinding wheel support 11 and wheel 12 for a rough grinding operation. At the end of the rough grind, a limit switch is actuated to reverse the supply to the device 95 which retracts spring 80 so that only spring 60 acts to urge the master cam and cam-shaft W against the follower and grinding wheel with a force insufficient to distort the cam-shaft. In an alternative embodiment, the second spring 80 is omitted and the device 95 acts on the abutment 62 which is then made slidable in the sleeve 53 to vary the tension of the spring 60 for rough and finish grinding.