Online Profile Spectral View for Process Troubleshooting Barry Beyer

摘要

Measurements for assessing real-time profile quality in the paper industry have generally failed to quantify some specific types of variation. On-line gauging systems for CD profile variation typically provide standard measurements of CD spread (2 sigmafrom average), Max-Min or Coefficient of Variation to describe CD profile variation. While this analysis does provide a general indication of CD variation, these measurements do little to identify waveform issues which impact final roll shape quality. A discrete Fourier transfer (DFT) routine was written to calculate wavelength and amplitude values in real time from data delivered by our QCS scanner. These values were then stored by our data historian. A second routine was written to analyze stored QCS data and back-populate the historian with spectral information. Correlation of the spectral data with other process data allowed us to troubleshoot a persistent profile problem and identify a mechanical source within the headbox.