In newspaper printing, breaking paper is a headache. Regardless of whether the paper is threaded manually or automatically, it takes more than 10 minutes to break the paper once. Frequent paper breaks make the operator miserable.
The author was fortunate enough to contact Manroland's UNISET and COLORMAN, and did some research. Now let's talk about the reasons for the paper break.
1. Crack or bruise.
If found in time, deal with it immediately, this fault is not a big deal.
2. There is a problem with the paper roll itself
If the quality of the paper is unacceptable or improperly stored, the center of gravity of the paper roll may be shifted, causing eccentricity. It is generally believed that paper rolls with an eccentricity exceeding 5 mm are considered unqualified, and eccentricity is likely to cause breakage.
Under normal circumstances, tension and braking force are balanced. When using an eccentric paper roll, due to the change in the radius R of the paper roll, the paper is subjected to an oscillation whose oscillation period gradually decreases and the amplitude gradually decreases. In each short period of time, the greater the startup speed, the greater the stress inside the paper.
3. The speed changes abnormally
4. Too much tension
The paper has a tension limit. When increasing the tension, try to stay away from the limit tension. At high speeds, a very small change can also produce very large stresses that can cause paper breaks.
5. When the paper supply must be stopped immediately due to other reasons, the paper cutter breaks the tape.
6. Ink for a long time and deposit ink on the paper guide roller.
For example, the tension of Manroland's COLORMAN offset press is controlled in stages. When the machine is turned on for a long time, the deposit of ink scale increases the radius of each roller, so that the tension also increases.
In addition, there are many paper guide rollers between the drum and the power roller, and the deposition of ink on it will also increase the tension.
When the tension is at the limit, the machine's paper machine will break the paper protectively.
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