| 摘要 |
A pair of pull rollers in a rotary printing machine, in particular an offset rotary newspaper-printing machine, consists of two driven pull rollers 7, 9. A ribbon consisting of a plurality of print-carrier webs 2, 3 is guided through between the pull rollers, with one of the pull rollers 9 having the ribbon 1 partially wrapped around it. Different web paths follow as a result of this. The difference in path, and hence speed, is greatest between the innermost and outermost print-carrier webs 2, 3. In order to achieve different conveyance characteristics in relation to the upper and lower side of the ribbon so that the webs can be fed to the downstream units at substantially the same speed and thus with the same tautness, one of the pull rollers, namely the inner pull roller 9 that has the inside web wrapped round it, is driven at a higher surface speed than the pull roller 7 that is in contact with the outer web. With the diameters of the rollers being identical this can be done by driving them at different rotational speeds. Alternatively, it is also possible to drive both pull rollers 7, 9 at the same rotational speed, with the diameter of the wrapped pull roller 9 being slightly greater than the diameter of the other pull roller 7 so that a greater circumferential speed results for the inner pull roller 9. |
