Solve the problem of double or multiple sheets in printing

1. The suction power of the paper separation nozzle is too large, and the following sheets of paper are simultaneously sucked up. This failure is caused by the following situations:

(I) The inspiratory volume is adjusted too much;
(2) The rubber band is too large;
(3) The separation nozzle is too close to the paper surface;
(4) The paper is too thin.

Solution: â‘ Reduce the air volume during printing; â‘¡Replace the small rubber ring, or cut the rubber ring small, and the rubber ring on the paper delivery nozzle can also be removed when the paper is thin; â‘¢Adjust the length of the paper pressure foot to increase The distance between the paper stack and the paper separation nozzle, or adjust the eccentricity above the paper separation nozzle rod to increase the distance from the paper stack surface; â‘£ Press the paper blocking brush down.

2. The separation nozzle is too close to the edge of the paper, or even beyond the edge of the paper, or the paper stacking is uneven, and the paper cutting size is inconsistent, which causes multiple sheets of paper to be sucked up by the separation nozzle at the same time.

Solution: During printing, the former adjusts the front and back position of the separator to increase the distance between the separation nozzle and the edge of the paper, and the latter should restack the paper. For unevenly cut paper, try to make the trailing edge neat when stacking; if the size difference is large and affects the accurate positioning, the paper should be changed or printed separately.

3. The height of the paper stack exceeds the allowable height of the paper stack. The height of the general paper stack should be about 5mm lower than that of the paper stack. Due to reasons such as paper curling or improper adjustment of the stack height, the stack height of the stack exceeds the allowable range, and double or multiple sheets of paper will be brought into the paper feeding table.

Solution: â‘ When the paper is upturned during printing, the paper can be knocked back; â‘¡The double sheets caused by the stack of paper being too high can be inserted into the wooden wedge for control. Offset presses such as J2203 and J2108 can also be solved by reducing the height of the separator. [next]

4. The paper trailing tip lifts upwards. When the airflow from the loose paper blower touches the edge of the paper, there is a circular arc on the edge of the upwardly curved paper. The airflow meets this arc and is divided into two parts. , The other part of the airflow turns downwards and cannot separate the paper, making the paper blocking brush useless. At the same time, the upturned paper edge is generally elastic. When the paper presser presses the paper, it shrinks, and when it is lifted, it lifts up again, causing double sheets, multiple sheets, and even paper to enter the paper feed one after another. station.

Solution: during printing â‘  Remove the paper and perform the paper knocking process; â‘¡ Adjust the angle of the bottom surface of the separation nozzle to keep it parallel to the paper stacking surface.

5. Too little paper pressure foot or paper brush to reach the edge of the paper. If there is too little paper pressure by the paper pressing foot, the paper stack will automatically rise and become unstable, making it unable to hold the paper underneath; the paper-blocking brush is too high or the paper edge is too little, and the effect of brushing the paper underneath is lost.

Solution: If the separation nozzle is on the edge of the paper during printing, the separator should be moved forward; if the edge of the separation nozzle is about 5mm away from the edge of the paper, you need to press the paper foot or paper brush Adjust to the standard working position (as described above).

6. The paper is not loose and sticky.

(1) Adhesion of white paper cutting incision.
(2) When printing semi-finished products, the previous color is full-plate solid or multi-color overlap. Due to the excessive thickness of the ink layer, the paper will stick up and down; water stains and ink stains are also prone to stick up and down.

Solution: During printing â‘  Before printing, the white paper should be slightly twisted, skimmed, shaken, and hit. â‘¡The semi-finished product is stuck due to the excessive thickness of the ink layer, and a small stack and a small stack should be shaken when loading the paper. â‘¢ Due to the small number of semi-finished products, the ink of the previous color is not dry and the adhesion occurs in the next color printing. When twisting the paper, it should be twisted several times repeatedly to allow enough air to enter between the papers to promote the oxidation and drying of the ink. The paper stack on the machine should be piled a little less, so as to avoid the adhesion of the paper below due to heavy pressure. [next]

7. The paper has static electricity. When the surfaces of two objects rub against each other, the electrons on the surface of one object will be transferred to the surface of the other object. When these two objects in contact are separated, because many electrons cannot return to the atoms they were originally in, this creates an inequality in charge. The paper is an insulator and has poor conductivity, especially in dry air, it is difficult to replenish the lost electrons. When the charge is stabilized in the formed area, static electricity is generated. Static paper can tightly attract another piece of paper or other objects in contact with it, causing difficulties in conveying paper during printing, causing problems such as skew, double sheets, multiple sheets, and uneven paper collection. When the static electricity is large , Or even stagnant on the surface of the conveying table, making production impossible.

The solution is a workshop with constant humidity and constant temperature control, and the relative humidity between the workshop and the drying room should be properly increased to keep the paper with a certain moisture content.

For workshops without constant humidity and constant temperature devices, some water can be sprinkled on the floor of the workshop. This treatment method has a certain effect on reducing the static electricity of paper, but improper treatment will cause the relative humidity of the workshop to be too high, causing the paper to expand and contract, resulting in the disadvantages of wrinkling and overprinting, so it needs to be used with caution.

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