Patent ID: 6840165
Filing Date: 2005-01-11
Classification: D21G

Abstract:
1. A method for determining when to open a nip of a calender comprising at least two elements brought into nip contact with each other, the method comprising: measuring tension of a web being calendered in the calender at multiple points over a cross-machine width of the web, the tension of the web being measured at at least one of upstream and downstream of the calender with respect to a travel direction of the web; determining when to open the calender nip based upon the measured web tension, a determination to open the calender nip occurring when, at a preset number of points over the cross-machine width of the web, the measured web tension has fallen below a limit value that is interpreted to indicate damage to the web less than a complete break of the web; and transmitting an instruction to open the nip of the calender when it is determined, based upon the measured web tension, that the calender nip should be opened.