Method for reducing web printing press start-up waste, and related printing press and printed product
A method for operating a web printing press is provided. The method includes unwinding a substrate from a roll to define a web; during makeready, printing the web using at least one print unit, the makeready ending when the web is being printed to a desired standard; stopping the web after the makeready; rewinding the web so that the substrate printed during the make ready pass back through the print unit; and unwinding again the rewound substrate to pass through the print unit. A press and printed product are also provided.
1. A web printing press comprising:
a roll stand for a substrate roll, the roll stand including a reversible motor;
at least one web guide for guiding a web unwound from the substrate roll;
at least one print unit for printing the web, wherein the at least one print unit includes a plate and blanket cylinder on one side of the web, and an impression cylinder on the other;
at least one sensor for sensing an image printed on the substrate
at least one curing unit for curing the printed substrate; and
a controller, the controller having a first output connected to the reversible motor, a second output connected to the at least one print unit, a third output connected to the at least one web guide, a first input connected to the at least one sensor, the controller determining from the first input if the image was printed to a desired print quality standard, and upon determining that the image was printed to the desired print quality standard, controlling the at least one print unit through the second output to throw the blanket and/or impression cylinder of the print unit off impression, then controlling the reversible motor and the web guide through the first and third outputs to continue to feed the web through the at least one print unit and the at least one curing unit until all printed images are cured; and then controlling the reversible motor and the web guide through the first and third outputs to rewind the web.
2. The press as recited in claim 1 wherein the sensor includes an optical density sensor or a register sensor.
3. The press as recited in claim 1 further comprising at least one web guide for guiding a web unwound from the substrate roll, the web guide being a reversing web guide.
4. The press as recited in claim 1 wherein the roll stand includes at least one web guide to insure proper rewinding.
5. The press as recited in claim 1 wherein the at least one print unit includes a plurality of print units for color printing of the web.
6. The press as recited in claim 1 wherein the print unit is a variable cut-off print unit.
7. The press as recited in claim 1 further comprising at least one counter for tracking substrate length.