A low cost, high accuracy roundness measuring system

This work presents a new architecture of a roundness measuring system in wh ich the roundness measuring accuracy is not dependent on motion accuracy of the rotary element. In this architecture, the influence of motion errors o n roundness measurement is minimized by applying a new error separation tec hnique developed by Horikawa et. al. [1,2], the improved Reversal Method - IRM. A prototype that uses: a rotary table supported by ball bearings, non- contact gap sensors and a computer system that collects and process sensor readings has been developed. Experimental results have shown that even usin g a rotary table supported by ball bearings, that has non-repetitive motion errors larger than 2 mum. the final measurement repeatability is better th an 0.3 mum of peak-to-peak value. In order to ensure the same levels of acc uracy of the proposed system, a traditional roundness measuring system desi gn must use a more precise and therefore more expensive type of bearing wit h a motion error no larger than 0.1 mum. (C) 2001 Elsevier Science Inc. All rights reserved.