Analysis of the cause of paper drop in offset printing process
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Paper drop refers to the phenomenon that the paper falls under the machine during the process of entering the paper to the delivery table. Paper failure will result in more waste and delay in production.
(1) The paper is uneven and wavy
Paper is not flat, making paper feeding difficult. Especially the whiteboard paper, it is easy to produce the front gauge paper is not in place, so that the paper pick-up paper is too small, and even the paper can not hold, so that the paper pick-up row and the transfer paper row can not be properly transferred and the paper is dropped.
(2) Paper paper corner upturn
When the paper goes to the previous position, the height of the tooth is lower than the height of the paper corner when the paper is raised, so that the paper can not be completely covered, even in the tooth decay. When the moment of closing touches the corner of the paper, the paper is ejected back, causing too little paper to fall off.
(3) Double sheets in paper feeding
When there is a double failure in the paper feed, the overlapped two sheets will appear a slightly faster, slightly slower condition. When entering the front gauge, the slow one may not be completely caught by the cavities and fall under the machine.
(4) Paper feeding is not normal
Due to improper adjustment of the machine, the paper is skewed, too fast or too slow, causing the paper to be unstable and the paper is lost.
(5) The pre-defined distance is incorrect
After the paper arrives at the pre-position, the gripper picks up the paper 4 to 6 mm. Too much is easy to tear the paper. Too little paper is lost due to insufficient paper.
(6) The contact time between the paper pick-up row and the impression cylinder is not correct.
If the paper pick-up paper is too early, it will break the paper; if it is too late, it will drop the paper because it can't hold the paper.
(7) The force of the paper tray is not enough
When the paper is discharged from the paper to half of the paper or only half of the individual rows of paper are caught, the force is too light and the paper should be re-adjusted.
(8) Positioning and paper feeding time are incorrect
When the paper arrives at the front gauge, the paper feed position is disordered due to the inconsistency between the speed of the paper and the connection time of the connection, and the paper is not good and the paper is dropped.