Troubleshooting the paper receiving system of the

Troubleshooting of the paper receiving system of the offset press

the paper receiving quality requirements of the paper receiving platform of the offset press are: loose, neat, and stacked flat, without corners, crushing losses, and greasy dirt. Especially for semi-finished printing products, it is required that the performance of the trailing tip, the bite, and the upper and lower positions should be reversed compared with that of the electronic universal experimental machine, so as to avoid irregular and messy paper receiving as far as possible. There are several reasons for the irregular receipt of offset press, which should be comprehensively checked, comprehensively analyzed and targeted during specific operations

in the offset printing process, due to the front, back, left and right paper handling baffles of the offset press's paper leveling mechanism, improper adjustment of the paper receiving teeth, improper adjustment of the paper brake, and poor flatness and uniformity of the paper, it is easy to cause the problem of uneven paper receiving of the offset press's paper receiving platform, and even cause the paper to have a corner to fold the printed matter out of the impression, affect the product quality, and bring trouble to the binding, sorting and statistics of the printed sheets

1. The distance between the left and right or front and rear paper handling baffles is too large, which is not suitable for the size of printing paper, resulting in uneven paper receiving. At this time, adjust the telescopic position of the left and right or front and rear paper handling baffles to make them the same size as the printing paper or a little larger

in addition, if the paper management baffle around the front, back, left and right of the paper receiving platform is not set at the right time, the printing paper will be blocked in the process of falling, and it will not smoothly fall into the paper receiving platform, which will also lead to uneven paper receiving. The position of the control cam of the paper management baffle should be adjusted to make its swing time consistent with the time of paper biting and placing, so as to ensure neat paper receiving

2. The paper receiving teeth in the chain paper conveyor are too early or too late to make the printed paper enter the paper receiving table accurately, and it is also prone to the problem of uneven paper receiving. At this time, it is necessary to improve the opening time of the paper receiving teeth at high speed, so that the paper can enter the paper receiving table in time

3. When the printed paper enters the paper receiving table, it moves upward, resulting in uneven paper receiving. This is due to the stress difference of the printing paper itself, on the other hand, it is caused by the failure of the suction wheel of the printing brake or the suction of the suction wheel is too small. The failure of the suction wheel is that the small hole in the suction wheel wall is blocked. Clean the paper dust and dirt on the suction wheel and use it. If the suction of the suction wheel is too small, its suction can be appropriately increased

4. When the printing paper enters the paper receiving table, it curls downward, causing uneven paper receiving. This is mainly caused by too much water in the printing plate, which makes the discrimination of the water content in the front and back of the printing paper too large. When printing, it is necessary to properly feed the water content of the printing plate, master the balance of water and ink, and use the minimum amount of water before the dirty plate, so as to reduce the bending deformation of the paper. So as to avoid uneven paper receipt

5. Due to the quality of the paper, such as poor flatness and uniformity, the paper will be rolled down, cocked up, arched, wrinkled, ruffled edges and other phenomena when entering the paper receiving table, resulting in uneven paper receiving. Before printing, the above paper with poor quality should be carefully hung and humidified. After hanging and drying, it should be stacked in the warehouse or offset printing workshop for a period of time. The paper stack should be put on the shelf with paperboard, and heavy objects (large stones, iron plates, etc.) should be pressed to make it flat. The paper on the machine should be knocked to increase the stress of the paper

6. If the paper is too thin during printing, it is often prone to uneven paper receipt. Due to the large size of offset printing paper (the cost can be reduced by more than 40% in quarto paper) and the need to moisten the plate with water at the same time, if the paper is too thin (such as 35 g/m2, 28 g/m2), after passing between the embossing cylinder and the rubber cylinder, the water will be transferred to the paper through the rubber blanket, and the paper will appear soft and unstressed, so it is difficult to receive the paper neatly, so it is best to keep the offset paper above 52 g/m2, To ensure that the paper is received neatly by the paper receiving platform

7 the relative humidity of the workshop is too low, and the water content of the paper is too low, which is easy to generate static electricity, so that the paper is firmly absorbed by each other and the delivery is uneven. In this case, electrostatic eliminators can be used to eliminate static electricity, or improve the relative humidity of the workshop, especially in dry weather in winter. If conditions permit, humidifiers can be used to regulate the humidity of the workshop. In addition, the offset printing workshop should open fewer windows, and the glass windows should be sealed. You can sprinkle some water on the floor of the workshop to regulate humidity

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