The analysis and measurement of motion errors of the linear slide in fast tool servo diamond turning machine

Xu Zhang,Qiang Liu,Pengzi Xu,Xiaoqin Zhou

doi:10.1177/1687814015575456

Abstract

This article proposes a novel method for identifying the motion errors (mainly straightness error and angular error) of a linear slide, which is based on the laser interferometry technique integrated with the shifting method. First, the straightness error of a linear slide incorporated with angular error (pitch error in the vertical direction and yaw error in the horizontal direction) is schematically explained. Then, a laser interferometry–based system is constructed to measure the motion errors of a linear slide, and an algorithm of error separation technique for extracting the straightness error, angular error, and tilt angle error caused by the motion of the reflector is developed. In the proposed method, the reflector is mounted on the slide moving along the guideway. The light-phase variation of two interfering laser beams can identify the lateral translation error of the slide. The differential outputs sampled with shifting initial point at the same datum line are applied to evaluate the angular error of the slide. Furthermore, the yaw error of the slide is measured by a laser interferometer in laboratory environment and compared with the evaluated values. Experimental results demonstrate that the proposed method possesses the advantages of reducing the effects caused by the assembly error and the tilt angle errors caused by movement of the reflector, adapting to long- or short-range measurement, and operating the measurement experiment conveniently and easily.

Highlights

Fast tool servo (FTS)–assisted diamond turning has been extensively used for compensating the motion errors of diamond turning machines[1] and producing freeform optical surfaces.[2]
Workpiece is clamped on the spindle, FTS is fixed on the slide of the machine which can move along the xaxis direction, and FTS can translate the cutting tool in and out of the workpiece as required.[3,4]
Since the slide is a linear motion component that can travel in a given trajectory and it is one of the important moving parts which can determine the surface roughness, the surface shape, and the relative position, analysis and measurement of the error motions of the linear slide are important for performance

Summary

Introduction

Fast tool servo (FTS)–assisted diamond turning has been extensively used for compensating the motion errors of diamond turning machines[1] and producing freeform optical surfaces.[2]. It means implementing multiple group measurements as the reflector samples at different initial positions relative to the coordinate system of the guideway Both the straightness and yaw errors of the slide can be estimated from the differential output of the measurement group data, and the tilt angle error caused by the movement of the reflector can be reduced from the measurement data. This shift sampling method integrated with the laser interferometer has advantage in error measurement. From equations (9) and (10), the straightness and the yaw errors can be obtained in the measurement length L

Experiments and calibration

Conclusion