Countermeasures for common electrical faults in th

2022-08-06
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Countermeasures for common electrical faults in letterpress printing

release date: Source: China paper

some problems in letterpress printing can not only give full play to the advantages of the experimental machine, but also the fault phenomenon in the letterpress printing process. Due to improper operation. Poor mechanical commissioning, wear of equipment components and poor substrate materials often lead to various failures, which not only affect normal production, but also reduce product quality. Most of the faults are caused by the paper position problems during the printing process. Next, I will take you to learn more about the relevant problems

1. misfeed

there are many reasons for misfeed. First, observe carefully to find out where the paper begins to skew, and then adjust it in turn according to the paper feeding sequence. Troubleshooting can start from the following aspects

(1) check the flatness and tightness of the paper stack to see if the paper itself is uneven in thickness, pressed, sunken, deformed, and tightness. Then, according to the existing problems, knock and shake the paper stack properly, so as to avoid the paper feeding skew caused by late suction and late feeding on one side of the paper

(2) check whether there is adhesion at the four sides of the paper stack, whether the paper pressing block at the trailing tip of the paper stack slides up and down flexibly, whether there is paper jam, and whether the rear paper stopper is too tight, so as to take measures such as shaking the paper edge, cleaning the attachments, adjusting the paper pressing block or the rear paper stopper for adjustment

(3) check whether the lifting and translation of the paper feeding suction nozzle are stable, whether the height is consistent, and whether there is any blockage, so as to adjust the paper feeding suction nozzle and remove the paper scraps and other obstructions

(4) check the tightness of the paper conveyor belt, whether the conveyor belt joint is flat, whether the roller pressure is appropriate, whether the steel plate of the paper pressing tongue is too low, whether there are foreign matters (such as loose screws) on the paper conveyor, and whether the side gauge is in normal working condition, so as to make corresponding adjustments

(5) check whether the rise and fall time and pressure of the front paper guide roller are consistent, and whether the paper guide roller rotates flexibly, and make corresponding adjustments to the existing problems

2. paper feeding empty sheet fault

empty sheet is a common fault in the paper feeding process. 4. sensor: the sensor is an important component of the accuracy and force measuring stability of the experimental machine. Generally, there are two situations: continuous empty sheet phenomenon and continuous paper feeding after empty sheet once. No matter what kind of empty sheet fault is, it can be checked and adjusted from the following aspects

(1) check whether there is bow wrinkle on the paper surface. If the bow wrinkle depression is aligned with the suction nozzle, it is bound to leak air and "break the sheet". You can knock the paper surface to change its uneven condition, or turn the paper around for printing, so that the flat paper surface is aligned with the suction nozzle

(2) check whether the paper stack is uneven. If the suction nozzle is low, it will not be able to be sucked up. Use cardboard strips or other objects to properly pad up and level the paper stack to make it meet the paper suction requirements

(3) check whether the edges around the paper stack are adhered. If there is foreign matter or water on the edge of the paper, or if the paper cut out with a blunt paper cutting blade is easy to adhere, resulting in paper suction difficulties and empty sheets, shake the paper properly

(4) check whether the air blowing rate is too small to blow up the upper paper edge, so that the distance between the suction nozzle and the paper surface is inappropriate and empty. The air blowing rate can be adjusted appropriately by increasing the air blowing rate

(5) check whether the vacuum suction is insufficient or the suction nozzle is damaged, and the suction pipe is broken and leaked in many supermarkets. Dredge the pipe, remove the blockage of foreign matters, and replace the damaged rubber suction nozzle and air duct

(6) check whether the angle and height of the suction nozzle and the paper stack are appropriate. If there is any discomfort, it can be adjusted as appropriate to make the paper level with the suction nozzle head and meet the height of the paper stack required by the suction nozzle

(7) check whether there is any discomfort in the position or angle of the paper separation brush and steel sheet, and properly adjust the brush and steel sheet according to the hardness of the paper

This will cause some friction between the swing bearings

(8) check whether the air pump works normally and whether the suction of the suction head is uniform. If the suction is large or small, it indicates that the air pump has problems and should be repaired

3. paper feeding double sheet or multiple sheet fault

(1) the double sheet fault is caused by excessive vacuum suction. Check whether the vacuum suction is enhanced due to the excessive diameter of the rubber suction nozzle, or the vacuum suction of the air pump itself is too large. For the former, a suitable rubber nozzle or no rubber nozzle can be selected according to the thickness of the paper; For the latter, the air suction volume should be reduced to achieve the effect of printing thin paper without absorbing two or more sheets

(2) double sheet fault caused by insufficient blowing volume. The reason may be the improper adjustment of the valve or the failure of the air pump, resulting in the blockage of the air path and the rupture of the pipe, which reduces the blowing air volume, and cannot blow several papers on the surface of the paper stack, resulting in double or multiple sheet failures. It should be checked and eliminated one by one

(3) the paper separation brush and steel sheet are not suitable to cause double sheet fault. The reason may be that the distance between the paper separation brush and the paper edge is too large, or the length and angle of the steel sheet are inappropriate. The position of the brush and the length and angle of the steel sheet shall be adjusted to keep the function of separating and loosening paper

(4) the suction nozzle is adjusted too low or the paper table is raised too high, causing double sheet fault. When the suction nozzle is too low and the distance between the suction nozzle and the paper stack is too small, it is easy to make thin paper double; If the paper table is raised too high, several paper sheets on the surface cannot be blown loose, resulting in double sheet absorption. The distance between the suction nozzle and the paper table and the lifting speed of the paper table shall be properly adjusted

to sum up, as long as the operator strictly implements the production process in daily production, abides by the operating procedures, scientifically and reasonably carries out equipment maintenance and commissioning according to the performance of the equipment and the characteristics of the substrate, carries out necessary treatment on the paper, and improves the printability of the equipment and paper, various failures can be effectively avoided

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