| 摘要 |
In the perforation of webs, such as in the perforation of paper webs in the production of business forms, a single perforating cylinder is utilized in cooperation with two anvil cylinders. Perforating elements, such as interrupted blades, extend outwardly from the periphery of the perforating cylinder and are rotated into operative association with the web passing between a first anvil cylinder and the perforating cylinder, and a second anvil cylinder and the perforating cylinder, to form first and second sets of perforations spaced a predetermined desired amount along the web. The length of the web between the first and second anvil cylinders is adjustable to control precisely the spacing of the first and second sets of perforations along the web, as by passing the web over a compensator roller mounted between the first and second anvil cylinders and movable toward and away from the perforating cylinder. The web may be directed in an alternate path bypassing the second anvil cylinder when the second set of perforations is not necessary.
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