Patent ID: 7311039
Filing Date: 2007-12-25
Classification: D21G

Abstract:
1. A method for preventing vibrations in a multi-nip calender or an array of multi-nip calenders, wherein each multi-nip calender comprises: a lower roll; an upper roll; and two or more intermediate rolls between the lower roll and the upper roll, the rolls defining a plurality of roll nips, wherein a plane is defined passing through the upper roll, the lower roll, and the intermediate rolls, a direction being defined lying in said plane; and wherein a fiber web is conveyed through the plurality of roll nips of the multi-nip calender or array of multi-nip calenders with the roll nips closed, the intermediate rolls being equipped with load-relieving means and the upper roll and the lower roll being equipped with first loading means within said upper roll and lower roll and second loading means being connected to the lower roll and/or the upper roll for loading said rolls towards the intermediate rolls in the direction of the plane of the calender, wherein running parameters are applied to each of the plurality of closed roll nips to apply a calendering impulse to the web, and wherein the entire multi-nip calender or array of multi-nip calenders applies an overall calendering impulse to the web to produce a web which leaves the multi-nip calender or array of multi-nip calenders with certain quality variables; the method comprising: continuously or intermittently changing the running parameters acting on the calendering impulse of one or more selected roll nips of the plurality of closed roll nips so that the overall calendering impulse of the calender or calender array and/or the quality variables of the fiber web remain substantially constant and/or within predetermined limits.