Abstract: There is provided a method for restraining deformation of a nip roll, in which polygonal deformation of nip rolls that are in contact with each other is restrained, so that vibration produced by the deformation is decreased. The diameter ratio between the first and second nip rolls 1 and 2 is set at a value different from 1, by which both of the numbers of polygon sides of the rolls 1 and 2 are prevented from becoming integers or values close to integers. Thereby, polygonal deformation of nip rolls that are in contact with each other, so that vibration produced by the deformation is decreased.

Abstract: There is provided a method for restraining deformation of a nip roll, in which polygonal deformation of nip rolls that are in contact with each other is restrained, so that vibration produced by the deformation is decreased. The diameter ratio between the first and second nip rolls 1 and 2 is set at a value different from 1, by which both of the numbers of polygon sides of the rolls 1 and 2 are prevented from becoming integers or values close to integers. Thereby, polygonal deformation of nip rolls that are in contact with each other, so that vibration produced by the deformation is decreased.

Abstract: A stock liquor pressure pulsation absorbing apparatus of an active type is able to absorb pressure pulsations in an ordinarily demanded frequency range of 0.01 to 100 Hz. A by-pass pipe (2) extracts a portion of a stock liquor from a master pipe (1) for supplying the stock liquor to a paper machine headbox. A control pump (7) returns a portion of the stock liquor so extracted into the by-pass pipe. A detector (3) detects a stock liquor pulsation pressure at a branch point, or on an upstream side thereof, of the by-pass pipe and master pipe for controlling the control pump. The pressure pulsation, including the low frequency range, of the stock liquor is thereby absorbed accurately and precisely, variations in the basis weight are made small and a stable supply of final products with a high quality can be attained.