Operational Experience With A Concept IV-MH Headbox, 1995 Papermakers Conference Proceedings

Scott B. Pantaleo Beloit Corporation William A. Wilson Bowater, Inc. Accurate, fine-scale measurement of basis weight profiles and profile variations are now commonplace on papermaking machinery. Paper quality and operational demands further require these machines to produce rolls of paper with less variation, even when measured on centers as small as 12 mm. Profile control using conventional slice bending is inherently limited by complex flow response, profile mapping difficulties, mechanical limitations, and interaction with fiber orientation. To meet current quality demands, a new headbox has been developed to improve flow stability, reduce variations in basis weight profile, and still reduce variations in fiber orientation. This headbox incorporates a unique flow tube for uniform flow across the machine width. In addition, control of basis weight profile is separated from fiber orientation control by adjusting local flow consistency. This paper reviews the design concept of this new headbox along with operational experiences using the headbox on a papermachine producing lightweight coated grades.