Precision measurement of carriage slide motion error of a drum roll lathe

This paper presents the measurement of carriage slide motion error of a drum roll lathe. The slide motion error, which is composed of the out-of-straightness error component and the axis misalignment error component between the axis of motion of the carriage slide and the axis of rotation of the spindle, is measured by using two capacitive probes placed on the two sides of a roll workpiece. The capacitive probes are first moved by the carriage slide to scan the stationary roll workpiece from the starting position to the end position of the carriage slide travel range before and after a 180° rotation of the workpiece about the axis of rotation of the spindle. The out-of-straightness motion error component of the carriage slide can be accurately evaluated by separating the influence of the workpiece out-of-straightness form error component based on the reversal method. The two capacitive probes are then kept stationary at the start position and the end position of the carriage slide travel range, respectively, to scan the rotating roll workpiece over multiple rotations. The axis misalignment error component can be evaluated from an averaging operation of the probe outputs of the capacitive probes over one rotation or multiple rotations, which removes the influence of the workpiece out-of-roundness form error component as well as the spindle motion error. Experiments were carried out on a drum roll lathe over a carriage slide travel range of 1700 mm.