Non-contact method of thickness measurement for thin-walled rotary shell parts based on chromatic confocal sensor

Abstract

In this paper, a non-contact method of thickness measurement for thin-walled rotary shell parts based on chromatic confocal sensor is presented. To obtain thickness, a flip method is applied to acquire surface profiles from both sides of the workpiece. The decentration and tilt errors of the workpiece are measured by a centering system consisting of a laser interferometer and a collimated tube. By establishing a unified reference coordinate system, the external and internal surface profiles are reconstructed and the thickness is calculated. A measurement experiment for a sapphire spherical shell workpiece was conducted on a four-axis measurement system and the result is 2.99341 mm. A wavelength-tuning interferometer and a dynamic interferometer were utilized to measure the sapphire spherical shell and an aluminum concave sphere and the results show in good agreement.