The development of an ultrasonic measurement for the prediction of paper strength properties - Part 1

摘要

Non-destructive and continuous measurement of strength during the making of paper has been an aspirational objective for the paper industry over the last 30 years. The major issues that have made progress in this area slow and have frustrated general implementation include difficulty in suppressing unrelated noise during measurement and the inability to usefully match the raw property measured by ultrasonic testers (generally, extensional stiffness) and those standard properties typically used to reflect paper quality.rnVariation of strength paper properties during the manufacturing process, unrelated to mass or thickness variation, has been estimated to be between 10 to 30% and is dependent upon the design of the paper machine, furnish and the chosen machine operating conditions. A method suitable for on-line estimation of desirable strength properties, such as ring crush and tensile strength, has been developed using ultrasonic measurement. The proposed method overcomes the problems that made previous measurement methodsrnimpractical.rnThis paper describes the measurement concepts that allow the use of ultrasonic measurement to progress to a form that is suitable for on-line measurement on the paper machine and presents correlations that relate common quality properties such as ring crush and tensile to the raw sonic test measurement.rnFurther, the implementation of a fast, nondestructive and accurate estimation of paper strength property allows enough data to be collected, at an appropriaternscale, to begin the process of understanding the cause of run-of-mill paper strength variation.