| 摘要 |
PURPOSE:To prevent breakage of paper by pressing a non-driven wide press roller, installed in a triangle plate drag roller part, to this drag roller only during slow operation, and thereby reducing local tension unbalance on the web likely to be otherwise generated during slow operation. CONSTITUTION:During slow operation, the printing unit 2 is in condition with the drum removed, while the transport path for web 1 remains the same as in high-speed operation, so that no printing is made on the web 1 throughout its width. The condition of the printing unit 2, i.e. whether the drum is set on or removed, is sensed by a drum sensor 10, and the signal obtained is sent to a control device 11. As the printing unit 2 is, at this time, free of the drum, a signal is given from said control unit 11 to a press roller set-on/removal device 9 to indicate that a wider press roller 5' shall be pressed toward a triangle drag roller 4. During slow operation, both the narrow 5 and wide 5' press rollers press and hold the web 1 by its greater width portion, which may reduce tension unbalance likely to be generated in the drag roller part 4 by the press rollers 5, 5'. Thus the paper is prevented from breakage. |
