Sheet-fed Printing and Wrinkling Technology Analysis (II)

Third, the impression of the impression cylinder teeth
In addition to the transfer of paper, the impression of the impression cylinder, but also the paper from the rubber roller to peel off, so it has a biting force must be greater than the peeling tension, and the size of the peeling tension depends on the printing pressure, print pattern distribution, ink viscosity And the surface condition of the blanket, so the resulting wrinkled paper condition is:

1 The lack of oil in the teeth of the teether may make the partial closure of the teeth may cause local displacement of the paper.

2 The smoothness of the teeth or the bite force of individual teeth is not sufficient to overcome the peeling tension, and the paper is partially released, especially where the pattern is relatively large;

3 bite teeth do not close together, and some teeth although the surface of the bite to see the paper, but the tooth and pad can not complete contact, in fact, the bite force becomes smaller, it is likely to make the paper out;

4 Others are similar to the paper handing situation.

Fourth, the problem caused by letter cylinder teething

The domestic four-color machine A-type, B-type machine before the transfer roller and double roller bite teeth may be lighter, as long as the opening and closing flexible and consistent on the line; then the transfer roller bite bite force should be greater, because the impression roller to the paper In the post-transmission, the second half of the printed sheet is still in the process of rolling. The transfer roller teething also has problems such as the breakage of the spring and the lack of oil in the needle bearings and the teeth. This causes the paper to wrinkle when it is imprinted.

The above mentioned problems with teething can easily cause the jaws to produce displacements or bite the edges during the paper handing process. If the teeth in the middle of the row of teeth are loose or the bite force is insufficient, the bite edges may partially fall out or bite. Paper bite edges will produce arcuate arch wrinkles; if the teeth at both ends of the row are loose or the bite force is insufficient, it will cause the paper to produce folds or diagonal wrinkles on both sides; if there is more than normal clenching, wrinkling will be More serious, we should first find out whether it is paper and paper, etc., and then check if there is any problem with the teeth. In fact, we should pay attention to machine maintenance at ordinary times, regular refueling to make the moving parts lubricated; if the tooth pad, tooth chip has been worn, it is recommended to change the entire vice teeth, flat teeth, the tooth pad surface should be in a straight line, the bite bite Together, open and close flexible and consistent. J2108, J2205 and other machines can adjust the bite force by adding a certain thickness of the sheet at the brake, and the four-color machine plus the tool roller can adjust the bite force at the high point.

V. Improper adjustment of side regulations
J2108, J2205 machine side lift time is 77 degrees, delivery paper bite paper time is 77 degrees, in the side adjustment process, if the side lift time is slightly later, there can be with the paper hand grab the paper, and Causes the paper to come out of the clenched teeth, resulting in paper-side diagonal wrinkles.

1 Imprinting cylinders are too thick to accumulate, which can cause the paper to deform and produce fine-grained wrinkles. Special attention should be paid when the semi-finished product is overturned. After the ink layer is dry, the cylinder will be heavily stacked. If you want to rush, you must Wash the rollers.

2 Paper feeding can also cause paper wrinkles if the paper is not mastered well. The heavy round of brush causes arching at the front gauge at the edge of the brush, especially when the paper with poor bones produces a relatively large wrinkle. This kind of paper should be Appropriate knock to increase the bite stiffness.

3 When the color of the front registration is large, the two corners of the mouth are upturned, and the lower sleeve color printing is easy to make the paper angle float to make the side of the paper wrinkle, and appropriately knock the paper.

4 If the printing pressure is too high, it may cause the paper to cause deformation. For thin paper, it will cause wrinkles.

5 The same printing pattern and pressure, for coated paper, produce a greater peeling tension than offset paper, and if the bite force is not enough, the paper can easily come off and wrinkle.

Six, to prevent paper wrinkles

The responsibility and predictability of a printing operator are required. The following points should be noted in actual production:

1 The machine should establish a strict maintenance system, especially the four-color machine has a lot of teeth, refueling work is very cumbersome, but we can not miss a tooth, is the production task is tight, should also see the seams to complete the refueling work , Found that tooth pads and other parts of the serious wear should be replaced.

2 To listen more to the weather forecast, especially in the rainy season or autumn and winter season, the temperature and humidity of the weather will change greatly. Once the “ruffled edges” and “tight edges” of the paper piles occur, a lot of waste and delays will be caused, so the semi-finished products should be strictly controlled. With protection, you can do a few caps to fit the paper stack properly.

3 To understand the use of paper for the next batch of jobs, paper with a shorter delivery date should be preconditioned.

Author: Wu Ming root Source: Jiangsu School of Press and Publication