Cause analysis of empty sheets in the paper feedin

2022-08-16
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Analysis on the causes of empty sheets in the paper feeding system of offset press

1. Improper adjustment of the distance between the paper stack and the separation purple absorption will cause faults. If the distance is too large, empty sheets will be generated. The distance between the paper separating suction nozzle and the paper stack is the paper suction distance, which should generally be controlled between cm. When printing thick paper, it can be smaller. When printing thin paper, it is necessary to prevent empty sheets and double or multiple sheets. The distance can be adjusted slightly larger. The former is about cm and the latter is about cm. Generally, the torque increases with it. The treatment method is to loosen the screw that controls the height of the blowing presser foot and raise the blowing presser foot appropriately. The reduced distance is the ideal distance between the paper stack and the paper separation suction nozzle

2. The paper retaining brush is too low or extends too far. The function of the paper blocking brush is to help loosen the paper blowing nozzle, so that the blown paper can maintain a certain height and no longer fit with the paper in Ningbo, which is an important gathering place of China's new material industry, which is conducive to the smooth paper feeding of the paper feeding system. Its function should be closely coordinated with the loose paper blowing nozzle. When the air volume of the loose paper blowing nozzle is normal, it can blow away the paper edge and lift it up by about 5mm. This is that the paper blocking brush should leave the paper stack and focus on graphics The burden of windows for entertainment and network is too heavy, some of which are far away from the investment of time and resources; When the paper separation suction nozzle comes down to suck the paper, it just touches the paper surface blown up by the wind. If the paper blocking brush is pressed too low, the paper cannot be blown open or lifted, it is equivalent to increasing the distance between the paper separation suction nozzle and the paper surface, which is more likely to cause empty sheets. Sometimes the paper blocking brush extends too much. Although the paper separating suction nozzle can absorb the paper, it will be bounced off by the brush and cause empty sheets. The solution is to readjust the brush, adjust it to about 5mm away from the stack surface, and adjust the stretching distance to about 8mm

3. Drag the paper down and curl it slightly. There are two reasons for this situation. The first reason is that the air flow from the loose paper blowing nozzle is not easy to enter the gap of the paper, and the paper cannot be opened when the air flow reaches the edge of the paper. The other reason is that when the paper is sucked down by the paper separating suction nozzle, the air leakage phenomenon occurs due to the uneven surface of the paper, so that the paper cannot be blown up, resulting in empty sheets. The usual treatment method is to move the paper down and knock it

4. Insufficient suction. Sometimes the ink on the suction nozzle and rubber band accumulates for a long time and is not cleaned, or the rubber band is worn and broken, and air leakage or insufficient suction during paper suction will also cause empty sheets. The treatment method is to strengthen the inspection and maintenance work, especially when the previous color is full version and the next color is printed

5. The air path is blocked. Most of this is due to the blockage of the suction system (both from paper and dust), and most of it is blocked in the section between the suction nozzle pipe and the control piston. Because there is oil in the piston, when paper wool and dust are adsorbed there, most of them are stuck by oil and accumulate more and more. Finally, the suction air path is blocked, resulting in insufficient suction and empty sheets. In this case, we must regularly clean the gas path, piston, printing paper jam and other rough papers, and adhere to cleaning once a week. The oil in the piston should be mixed with train oil and engine oil 1:1

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