Monitoring the Mechanical Behavior of Paper During Papermaking, 1999 International Paper Physics Conference Proceedings

Pierre H. Brodeur, Joseph P. Gerhardstein, Emmanuel F. Lafond, Jimmy H. Jong, Charles C. Habeger, Brian M. Pufahl, Vance A. Deason, Kenneth L. Telschow, Yves H. Berthelot

Monitoring the mechanical behavior of paper during papermaking has long been sought after for one main reason: it would enable real-time control of the papermaking process. Implications of this achievement are substantial: optimized use of raw materials, reduction of operating costs, energy savings, and performance optimization of paper products. We report in this paper a research program aimed at providing the missing measurement and data interpretation tools to support the future development of real-time process control strategies during papermaking. The program has two major objectives: 1) develop and field test the necessary hardware to gather on-machine information on the mechanical behavior of paper; 2) use this information along with already existing information such as grammage and moisture content to begin an investigation of the inverse problem of predicting papermaking process conditions from measurements. The rationale for real-time monitoring of paper stiffness is first introduced. Then, the concept of simultaneous detection of stiffness orientation distribution (SOD) and fiber orientation distribution (FOD) to extract the contribution of built-in stresses to the overall sheet stiffness is presented. An overview of the research program is next reported. Finally, the demonstration of stiffness measurements on moving paper at production speeds using a noncontact laser ultrasonics method is briefly reviewed.