| 摘要 |
To prevent damage to a printing cylinder, typically the blanket cylinder of rotary offset printing machine, upon tearing of a paper web, which usually occurs within a dryer, a paper web seizing apparatus is positioned downstream of the last printing station. The apparatus includes a roller (15) which is driven at the speed somewhat higher than the linear speed of the paper web by a belt drive (20,21,22) from a friction wheel (18) and held out-of-engagement with the other roller (3) of the pair by a latching mechanism (24, 25, 26-FIG. 2). Upon sensing of a tear, the electromagnetic (26) of the latching mechanism permits a spring (23) to disengage the first roller (15) from the friction drive (18), the roller continuing to rotate due to inertia and engaging the web (A) and then being driven by the positive drive (8,9,10) of the first roller, thus wrapping any torn web about the first roller and preventing damage to the printing cylinders of the printing machine.
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