The cause and solution of the hottest paper foldin

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Causes and solutions of paper folding (I)

after the paper enters the drum and is subjected to pressure, it forms bending or irregular folding marks on the paper surface, which is called folding, commonly known as pleating. It is a common fault for a flat paper to wrinkle after being rolled by the roller, which seriously affects the registration accuracy

there are two reasons for paper wrinkles: one is the improper adjustment of machine parts, and the other is the physical and chemical properties of the paper itself

improper adjustment of a machine part causes

1 uneven bite force of the imprint cylinder

when the paper is bitten by the imprint cylinder, the bite of the paper is uneven. One case is that the bite force of two or more adjacent teeth at a certain position on a row of teeth is too loose. When the cylinder is pressed, the paper is pulled out by the squeezing force and stripping force between the rollers, so that the part of the paper with too loose bite is pulled out, Wrinkles are produced under the action of roller extrusion, as shown in Figure 1 (a)

(a), which is called sporadic folds

another situation is that the bite force of two adjacent teeth at a certain position of a row of teeth is greater than that of other teeth. After the roller is pressed, the paper with light bite force is pulled out during the experiment, resulting in convergent folds. For example, with the gradual promotion of the new medical reform and equipment policy, figure 1 (b)

another situation is that the bite force of several teeth in the middle is too light, Or the diamond pattern of the tooth pad is worn, resulting in small friction force. Under the action of stripping tension, the middle part of the paper bite is pulled out, resulting in arc-shaped folds, as shown in Figure 1 (c), which is common on two-color and multi-color offset presses

2. The positioning position of the side gauge is improper, so that when the paper reaches the positioning of the front gauge, the corner edge of the paper collides with the gap between the paper delivery tooth pad and the tooth table iron plate, or the corner edge of the paper or itself is tilted upward, so that the paper cannot be transmitted straightly from the paper delivery tooth to the impression cylinder teeth, or the corner edge of the paper is far away from the teeth at the extreme end of the teeth shaft. Generally, the round test piece should be placed in the V-shaped groove for testing, especially when the paper is full, the paper corner is easy to float, The impression teeth may not be able to bite the corners of the paper correctly, and skew folds will occur after stamping, as shown in Figure 1 (d). Sometimes, because the lifting time of the side gauge is slightly slow or the bite force near the outermost end of the paper delivery tooth outside the side gauge is too light, there will be no obvious wrinkles

(to be continued)

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