Grinding machine and method

Abstract

An improved method and grinding machine are used to grind lobes on a camshaft. The grinding machine includes a longitudinally extending rocker bar which is pivotally mounted on a work table or carriage. A headstock and tailstock are connected with the rocker bar to rotatably support the camshaft as the cam lobes are ground by a grinding wheel. A control assembly includes a motor which is operated to pivot the rocker bar from a retracted or loading position through an index position to an operating position in a range of operating positions. Immediately before the rocker bar reaches the range of operating positions, the speed of the motor is reduced to effect a corresponding reduction in the speed of movement of the rocker bar. In addition, the motor actuates a biasing assembly to urge the rocker bar toward the camshaft with a relatively large force during a rough grinding operation and a reduced force during a finish grinding operation. During the rough and finish grinding operations, a master cam assembly and follower cooperate to move the rocker bar in the range of operating positions as a function of the desired cam lobe configuration. The cam follower is movable into alignment with a selected one of a plurality of cam elements in the master cam assembly by a motor which is mounted on the carriage. A stop member is utilized to stop the rocker bar when it has moved away from the grinding wheel to the index position. This enables the cam follower to be aligned with a selected master cam element between the grinding of successive lobes on the camshaft without moving the rocker bar all the way back to the loading position. When the grinding of the camshaft is completed, the stop member is retracted to enable the rocker bar to be pivoted to the loading position.