Machine tool fault indicator

Abstract

The crankpins of a crankshaft mounted in a workpiece carriage are successively ground to a desired size by a sequence of movements of a grinding wheel moved under the control of a control circuit. The crankshaft is mounted in clamping mechanisms latched closed and rotatably driven by associated headstocks. During the grinding operation, each crankpin to be ground is axially positioned by an axial locator mechanism mounted on a positioner mechanism which is moved between rest and operating positions, and the final grinding of each crankpin is effected while a retractable work rest mounted on the positioner is pressed against the crankpin. After each pin is ground, the workpiece carriage is traversed and the crankshaft is rotated to position the next crankpin for grinding, and when the final crankpin has been ground the machine returns to an initial position where the clamps are unlatched and opened to enable the ground crankshaft to be replaced by another workpiece. The movements of the various mechanisms of the machine are detected by the operation of limit switches and other switches interfacing with a sequence controller which produces signals continuing the operation of the machine. To facilitate the detection and correction of a fault condition disabling the automatic operation of the machine, a fault detector arrangement is provided which senses an incorrect initial condition by the absence of the operation of one of the limit switches and provides a visible indication of the fault by energizing a light associated with the particular fault.