Web-Wide Diagnostics of Paper Properties based on Fault Detector System Images

摘要

The fault detector system consists of multiple cameras imaging the whole paper web in CD. The systems are focused to detect imperfections of paper based on light transmittance images. Therefore, the images are not directly suited for small-scale analysis of paper properties. This paper studies the forming of 2D web-wide image based on fault detector system images. Uneven illumination, geometrical distortions and overlap areas are removed to obtain undistorted web-wide image. The applicability of web-wide images in diagnostics of variability in paper properties and quality management of paper is discussed. Tilted waves which are caused by the effects in headbox are observed in the web-wide image. Tilted waves may represent severe variation in paper properties and quality. Online shrinkage profile of paper gives valuable information to manage the quality of paper and true cross-directional control. In this work both the length and pixel resolution of web-wide image was sufficient for successful estimation of the shrinkage profile. The shrinkage profile estimate was found reliable and stable.