Fresnel diffraction for fast and accurate in-process measurement of the diameters of rotational symmetric workpieces

The paper presents an innovative instrumentation for in- process measurements of the actual diameters of workpieces with rotational symmetry. This instrumentation may readily be integrated into turning or grinding machine, e.g. for the ends of quality assurance and to make an automatic compensation of deviations of diameters possible. It consists of two optical Fresnel diffraction sensors mounted diametrically to the nominal axis of the workpieces under process such allowing a fast measurement of their actual diameters with errors less than +/- 5 micrometers at scanning rates of more than 1 kHz. An automatic follow-up system, based on grated glass scales has been constructed to achieve the requirements of a resolution of 1 micrometers up to diameters of 300 mm. Special high precision guide rails and bearings have been constructed to minimize the effects of imperfect guiding to the over-all accuracy. Variations of the ambient temperature doesn't effect the results since the complete instrumentation is in a housing at stable temperature. High pressure jets make sure that the workpiece surface in the measurement areas are blown free from oil, cooling fluids, and chips.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.