Measurement of Straightness of High Aspect Ratio Thick Walled Cylinder-A Concept

Productivity in manufacture of high aspect ratio cylinders depends on how quickly the inspection parameters are measured and corrective actions are token. Long cylinders undergo a series of processes including bend removal and machining. These processes undergo a series of iterations consuming considerable amount of time for the measurement of straightness of cylinder. In this paper, a concept is proposed, where, the straightness of the bore of a cylinder (barrel) is measured in-situ on the machine. In this method, the barrel diameter and thickness are measured at number of planes using touch trigger probe and ultrasonic transducer respectively. Ultrasonic transducer assembly and the touch trigger probe are mounted on the turret of the CNC Turn Mill Centre. The setup for ultrasonic based measurement includes a nozzle for the supply of stream of liquid on the work piece, an ultrasonic transducer and a data capturing unit. Echo from ultrasonic waves is obtained back from the stream enabling the measurement of the relative position from the outer profile of the work piece to its internal profile. By orienting (rotating) the work piece at different locations in the same plane, thickness and diameters are measured. Straightness is measured by continuing to measure along the length of the cylinder. The thickness and diameters obtained are then used for the evaluation of straightness of the bore.