Abstract: The problems caused by chemical and thermal shrinkage of hard roll covers, are reduced by the inclusion of one or more intermediate compressive layers between the metal roll and the outer cover, or "topstock". A compressive layer has the properties of being rigid enough to allow the cover to be applied to the roll, and compressible enough to buffer and absorb the stresses which occur as the cover is shrinking during processing.In one embodiment, the intermediate compressive layer comprises a three dimensional fabric that is filled preferably with a thermoset resin system which cures at lower temperature than cover. In a second embodiment, the precise amount of shrinkage in the roll can be predetermined to a high enough degree of accuracy so that a depth for the fabric layer can be used to compensate for the amount of shrinkage, thereby eliminating the need for filling. In a third embodiment, the compressive layer is comprised of a wax material.

Abstract: A roll system for use particularly in a papermaking press nip for dewatering a fibrous web, comprising a roll disposed so as to rotatingly cooperate with another roll in a press nip, the roll having a helical sensor for sensing pressure exhibited on the roll, and transmitting pressure signals to a processor as the roll rotates. Trigger signals are generated at certain times as the roll rotates, the time of the occurrence of the trigger signal representing a specific location on the helical sensor. The pressure signals are coordinated with the trigger signals, such that the pressure corresponds to the angular position of the roll where it is sensed. The operator may thus be given a visual or audible indication of the existence of non-uniformities in pressure sensed at various locations along the roll, thereby enabling corrective action to be initiated if necessary.

Abstract: A system for measuring the dynamic pressure distribution between rolls in a nip roll press comprises a roll adapted to rotatingly contact at least one other roll in a press nip, having one or more sensors thereon, for measuring the nip pressure at several locations along the roll length, wherein the measurements obtained by the sensors are transmitted to a computer and a display, to provide tabular, numerical and graphical representations of the pressure at one or more locations on the roll. Optionally a control system may be incorporated in the system for determining the pressure distribution along the roll and initiating corrective measures. The system of the instant invention can further measure temperature variations, if desired, as thermal sensors can be used on the sensing roll, or a computerized correlation scheme can relate sensor readings to temperature as well as pressure.