Patent ID: 7040231

Claim:
A method for regulating elongation in a paper web in a rotary printing press including: providing at least first and second printing units in the printing press; passing a paper web through said at least first and second printing units in a direction of web travel; providing a marker on the web at said at least first printing unit; measuring a first phase position of said at least first printing unit using said marker; measuring a second phase position of said marker on the web downstream, in a direction of web travel, of said at least second printing unit; determining an actual value of a phase shift as a difference between said first phase position and said second phase position; providing a reference value phase shift; comparing said actual value phase shift with said reference value phase shift to determine a phase shift deviation value; providing a means for regulating a tension in said web upstream of said at least first printing unit; using said tension regulating means for regulating an initial elongation of the web prior to said first printing unit in response to said phase shift deviation value of said actual value phase shift from said reference value phase shift; and maintaining a resultant web elongation constant after a last one of said at least first and second printing units in said direction of web travel, by regulating said initial web elongation of the web prior to said first printing unit by using said tension regulating means upstream of said at least first printing unit for regulating said initial elongation of the web prior to said first printing unit.