1. Mechanical reasons
1. The pressure of the pressure roller of the feeding table is uneven
The paper is subjected to the axial force during the conveying process, causing the paper to bulge in the middle when the paper is in the previous position, forming wrinkles after stamping.
2. The gripping force of the gripping cylinder of the impression cylinder varies
If the gripping force on both sides of the platen of the impression cylinder is insufficient, the trailing edge of the paper is wrinkled; if the gripping force on one side is insufficient, the corresponding trailing edge is wrinkled; if the gripping force in the middle is insufficient, the middle of the paper Wrinkle.
3. Improper handover of paper
In the process of handing over the paper before imprinting, if the fit is improper, causing the length of the paper at the edge of the grip to change, the trailing part is likely to wrinkle.
4. The unevenness of the dental pad
When the paper is gripped, if the dental pad is not flat, the edge of the paper will be wavy, and the gripper will be partially wrinkled. "
5. The position of the paper edge and gripper is incorrect
After the paper is positioned, if the paper is gripped by the teeth a little, the edges of the paper are uneven and wrinkled. +
6. The ink sticking on the surface of the impression cylinder is too thick
The thickness of the ink adhered on the surface of the impression cylinder is too thick, which makes the paper uneven when it is imprinted, and also produces local short-distance wrinkle deformation.
Second, the paper reason
1. The trace of paper knocking is too deep and too dense
Due to improper knocking on the paper, the traces of knocking paper are too deep and too dense, and wrinkles are easily generated in the folds of knocking paper during printing.
2. Paper thread direction
When the paper enters the machine for imprinting, if it is a straight thread, it is easy to cause wrinkles.
3. Paper moisture content is too large
If the moisture content of the paper is too large, the fiber of the paper itself expands. During the imprinting process, the expanded fiber narrows from hypertrophy, and it is easy to produce branch-like wrinkles that extend from the mouth to the trailing direction.
4. The influence of environmental temperature and humidity
The temperature and humidity of the environment change, resulting in uneven water content of the paper. If the water content in the surrounding is greater than the middle, the lotus leaf edge is generated, and the paper is easily wrinkled during printing. [next]
Handling of wrinkled paper
1. Disposal of paper used
When the wrinkles of the printed matter are found, first of all, carefully observe the wrinkled position, size, shape, etc. of the paper, and make a judgment and analysis to see whether the paper is wrinkled at one end, or whether it is wrinkled at both ends. Some are wrinkled, some are not wrinkled, or only individual papers are wrinkled. Take another look at whether it is a large fold, a dark fold, or a wrinkle at the mouth; then, check whether the white paper is smooth and there are serious paper quality problems such as ruffles. At the same time, find out if other machines print the same job on the same paper, and whether they are wrinkled. If the products printed on each machine are wrinkled, it means that the paper is obviously not good, or it is too new, too wet, etc., and it needs to be changed. You can also turn the white paper upside down and replace the bite. Test whether the paper continues to wrinkle. It is no longer possible to knock the white paper out by folding it, so that the paper changes from soft to crisp. Then try printing again to see if the wrinkles can be eliminated. If it still does not work, you can use the paper dryer to dry the white paper again and then print.
2. Handling of printing machinery
When the same paper is printed on other machines without wrinkling, it means that the machine of the machine has a problem. After the white paper is turned over and the position of the paper wrinkle has not changed, it can also be concluded that there is a problem with the machine, and it is necessary to check and adjust the bite of the imprinted teeth and the swinging teeth. Under normal circumstances, the adjustment (impression or placement) of individual teeth will be effective, and sometimes it is different. Simply adjusting individual teeth will not help at all. You need to loosen all teeth and adjust them together. During the adjustment process, if you find that there are The dental tablets or pads are badly worn, and should be replaced in time until the mouth of the teeth is consistent and the bite force is consistent.
3. Deal with the drum lining accordingly
When printing thin paper of large format, wrinkles are found, and after a series of treatments such as paper change, reversing, knocking, drying paper, and tooth adjustment, and it still does not work, you can deal with the liner in the rubber roller. Remove the liner paper inside the rubber to reduce the pressure between the rollers. If you continue to wrinkle, take out all the lining, and then use a blade to divide the pad paper. When dividing, keep a sheet close to the roller, the paper clip is not cut off, and the print bite to the blank of the trailing edge. The center of the space is a tangent line, which is cut open, so that when reprinting, the pressure area becomes smaller accordingly, and the phenomenon of wrinkling disappears.
4. Emergency treatment for wrinkling of paper
There are many ways to deal with paper wrinkling. Sometimes the paper is wrinkled. Check that the two ends of the impression cylinder are badly worn. You can paste wide tape on both ends to make it work. Sometimes the wrinkling of the paper is due to the excessive pressure between the rollers, and the pressure of the rollers can be reduced slightly. Sometimes, some special situations are encountered, such as: some printed products urgently need to be cycled, and the paper is wrinkled when printing. The reason for the wrinkle is that the impression roller has individual teeth and the paper is bulging and uneven when biting the paper. Monotonous teeth will not help. If all the impression teeth are adjusted again, it will delay time. For emergency, you can use this tooth Temporarily remove it first, so that when it is printed again, it will not be wrinkled by the teeth, and the paper will no longer wrinkle. After the batch of work is completed, the teeth will be reinstalled and fully adjusted. There is also a situation where the wrinkled position is at the corner of the paper, because the paper is upturned, and when pulled by the pull gauge, the upturned paper corner happens to touch the tooth pad that swings the teeth, such as a moving pull gauge, It will lead to changes in the regulations and cause trouble for the next printing. For this, an emergency measure can also be taken, that is, the tooth pad that is obstructing it is temporarily unscrewed with a wrench, so that it will no longer wrinkle and print the printed product. After that, install the dental pad again and readjust.
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