Wrinkling of paper is one of the problems that printers often encounter. It is caused by many factors. Machines, such as cavities, tooth pads, different lengths of dental chips, uneven, loose and inconsistent, when the edge of the paper is not smooth, when the imprinting paper local displacement, when the paper will appear the weight of wrinkling wrinkles . Some people think that it is okay to swing the force of the gums. Just pick up the paper. In actual fact, the overall swaying of the oscillating teeth is not the same as that of roller cavities, which also causes the paper to wrinkle. In addition, if the paper feeding time is inaccurate, the timing of drawing the paper is not correct, and the pressure of the paper feeding roller on the paper feeding board is different. Wrinkling occurs when the paper is pressed. Paper itself, such as uneven water content, flounces appear, the new paper contact the air quickly after the edge of the moisture deformation, after the imprint will have a certain deformation and make the paper wrinkles.
One example of paper wrinkles we encountered was this: When the J2108 machine printed 850mm×1168mm paper, wrinkling occurred at about 5-8mm from the edges of the paper, and the drag was more serious. When checking all the parts to confirm that there is no problem, wrinkles are still appearing repeatedly. 'Increasing or reducing the swaying force of the oscillating teeth and the drum teeth is not effective. Again, the rubber and impression cylinder shell gaps and liners were inspected and no cause for wrinkling was found. Later when cleaning the impression cylinder, it was found that the surface of the impression cylinder was not even. So we analyze the reasons, in the printing of books and more 787mm × 1092mm paper-based, drum shell often piled on the ink, both sides easily accumulate ink, the operator does not thoroughly clean the surface of the impression cylinder, two long without rubbing, Ink dry.
Due to the frequent use of a blade spatula, rubbing with pumice powder causes wear on both sides. When replacing the large size 850mm x ll68mm paper, the large parts on both sides are just in the worn part, thus forming a certain gap in the imprinting. After confirming this reason, we first applied 0.1mm thick kraft paper on both sides of the impression cylinder on both sides, and the wrinkling was significantly reduced. After affixing a piece of kraft paper, the wrinkling disappeared completely. Since we do not have a gauge for accurate measurement, it is estimated that at least two ends of the impression cylinder wear 0.15-0.2mm. Hope that the majority of offset press operators must pay attention to the maintenance of the surface of the impression cylinder, especially the long-term printing four printing paper manufacturers, should pay more attention to maintenance of the impression cylinder, or replace the large-size paper or printed color products, there will be failure.