Spindle error motion measurement of a large precision roll lathe

Abstract

This paper describes a spindle error motion measurement system to evaluate the performance of the spindle of a large precision roll lathe, which is under development for fabrication of large-scale roll dies of micro-structured surfaces. The measurement system employed a large-scale roll workpiece with a diameter of 320 mm and a length of 1800 mm as a measurement artifact instead of a master object to figure out the spindle error motion over the entire fabrication length. To separate the spindle error motion and the out-of-roundness of the roll workpiece, the reversal method was employed. Two capacitive type displacement probes were mounted on the designed probe holders which were arranged to be faced to each other with the roll workpiece between them. Spindle error motion measurement was conducted at several sections of the roll workpiece along the roll axis to verify the tilt error motion of the spindle as well as the radial error motion. As the rotational speed was different for the mirror finishing fabrication of the roll workpiece and fabrication of the micro-structures on the roll workpiece, the spindle error motion was measured at rotational speeds of 5 and 300 rpm, respectively. Experimental results of the out-of-roundness of the roll workpiece as well as the spindle error motion measurement are presented in this paper.