COMPLIANT HYDRODYNAMIC HYDROSTATIC SHOE FOR PAPERMAKING PRESS

摘要

A press of the Beloit Extended Nip ~ type has a nip defined between a backing roll and an elongate shoe. A paper web travels on a dryer felt through the nip and is supported over the shoe by a bearing blanket. The shoe has a rigid concave core to which is fixed a layer of compliant material which defines a concave surface. Lubricant is introduced between the compliant material and the bearing blanket to form a hydrodynamic fluid film. Preferably the rigidity of the compliant material is of the same or lesser order of magnitude than the rigidity of the fluid film at the center of the shoe in the machine direction, such that the fluid film at the nip causes a depression in the compliant material which is filled with lubricant. The thickness of the lubricant is thus greater at the center of the shoe than at regions outward from the shoe center and the escape of lubricant from the shoe is retarded. The compliant material comprises an elastomer with a low coefficient of friction and high abrasion resistance. It has the ability to deform with increased pressure upon it, thus allowing a paper wad or web deformity to pass through the nip without damage to the bearing blanket. Alternatively, the compliant layer may define a plurality of lubricant pockets.