| 摘要 |
A fixed cutoff press is adapted to a variable cutoff press while maintaining the size of the blanket cylinders. A plate cylinder is mounted on a frame and includ es a plate cylinder sleeve and a blanket cylinder is mounted on the frame, includes w ith a gapless blanket cylinder sleeve. The gapless blanket sleeve contacts the plate c ylinder sleeve at a first nip. The press has an impression plate mounted on the frame in the case of a non-perfecting press or an identical, mirror image assembly of plate and bl anket cylinders in the case of a perfecting press. A material to be printed passes thr ough a second nip. Inkers are provided for transferring an ink film to the plate cylind er sleeve, the ink pattern being subsequently transferred to the blanket cylinder sleeve at the first nip and the ink pattern being subsequently transferred from the blanket cylinder sleeve to the material to be printed at the second nip. The press also includes drivers to drive in rotation the plate cylinder and drivers to drive in rotation the blanket cyli nder. A controller is provided for controlling each of the drivers so that the surface s peed of the sleeve of the plate cylinder and the surface speed of the blanket cylinder sleev e are equal at the first nip. The plate cylinder sleeve is variable, whereby a length of an image to be printed is varied proportionally to the variable outer diameter while maintainin g the outer diameter of the gapless blanket cylinder sleeve constant. Accordingly, sin ce the size of the blanket is fixed and offset presses presently require changing plate s for each job, changes in cutoff are made in a manner similar to today, i.e. plates but no t blankets are changed for each job. Ideally, the residual ink on the blanket, once the ima ge is transferred to the web, is small enough that a secondary image will not appear o n the web. The invention also provides for the inclusion of a blanket washer or scrapp er, which continually removes the residual ink and recirculates it through the ink t rain to avoid any secondary images.
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