Importance

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Abstract

A calender press for use in a paper-making machine includes a top roll positioned adjacent to a nip and rotatable about a longitudinal axis thereof. The top roll has a length and circumferential perimeter. The length extends in the direction of and is longer than the width of the fiber web. The top roll is thermally compensated in a plurality of thermal zones which are adjacent to each other across the length of the top roll, whereby the perimeter of the top roll may be adjusted in a locally adjustable manner toward and away from the nip. A bottom roll is positioned adjacent to the top roll and defines the nip with the top roll. The bottom roll is rotatable about a longitudinal axis thereof and has a length and circumferential perimeter. The length extends in the direction of and is longer than the width of the fiber web. The perimeter is smaller at each longitudinal end of the bottom roll and larger at approximately a midpoint between the longitudinal ends, thereby defining a crowned bottom roll. The bottom roll is thermally compensated in a plurality of thermal zones which are adjacent to each other across the length of the bottom roll, whereby the perimeter of the bottom roll may be adjusted in a locally adjustable manner toward and away from the nip. The thermal compensation of the bottom roll and the top roll coact to effect a nip load of less than approximately 150 pounds per linear inch between the top roll and bottom roll.

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First Claim