In-process roughness quality inspection for metal sheet rolling

A reliable in situ inspection of working rolls’ surface quality requires fast roughness measurements with >0.5 m2/min on a nanometer scale. A speckle-based measurement approach is realized using a high-speed pulse laser and FPGA-based image processing to inspect surface areas with a diameter of 1 cm without motion blur with 200 Hz. As a result, a roughness resolution below 0.5 nm is demonstrated under manufacturing conditions, which mainly results from light source intensity fluctuations. The surface quality inspection is finally validated on the rolling wheel in a reconditioning process to detect the tool roughness distribution and respective tool wear.