Analysis and Countermeasures of Common Electrical Faults in Letterpress Printing

Some failures in letterpress printing are in the process of letterpress printing. Due to improper operation. Poor mechanical debugging, wear of equipment components, and poor material quality of the substrate often lead to various failures that not only affect normal production but also reduce product quality. Here I will analyze some common faults.

1. Paper feed skew failure

There are many reasons why the paper is skewed. First, a careful observation should be made to find out where the paper starts skewing, and then adjust the order of the paper in order. Troubleshooting can start from the following aspects.
(1) Check the flatness and tightness of the paper stack to see if the paper itself has uneven thickness, deformed depressions, and uneven conditions caused by uneven tension. Then, according to the existing problems, appropriate Tap and fluff loose to avoid paper feed skew due to late suction and late feed on one side of the paper.
(2) Check whether there is any adhesion on the four sides of the paper stack, whether the paper press block at the paper pile tip is slid up and down, whether there is a paper jam, and whether the rear stopper is too tight, so that measures can be taken such as fluffing the paper edge and cleaning the attachment. Keep an object, adjust the pressure plate or rear block to adjust.
(3) Check whether the paper feeding nozzles are stable in lifting and translation, whether they are the same in height or not, and whether they are clogged, so as to adjust the feed nozzles and remove jams such as paper dust.
(4) Check the tightness of the conveyor belt, whether the conveyor belt joints are smooth, whether the roller pressure is appropriate, whether the pressure paper tongue steel block is too low, there is no foreign matter on the paper feeding board (such as loose screws), side gauges Whether the working status is normal, so as to make corresponding adjustments.
(5) Check whether the landing time and pressure of the front paper guide roller are the same, whether the paper guide roller is flexible, and make adjustments according to the existing problems.

2. Paper empty sheet failure

Blank sheet is a common fault in the paper feeding process. Generally, there are two cases: continuous empty sheet phenomenon and continuous sheet feeding after empty sheet. No matter which kind of sheet sheet is faulty, 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 will inevitably leak “broken”. You can tap the paper surface to change the uneven condition, or turn the paper around and print it to make it flat. The paper is aligned with the nozzle.
(2) Check whether there is any unevenness in the paper stack. If the nozzle part is too low, it will not be able to be sucked up. It can be properly uplifted with cardboard strips or other objects to flatten the paper stack so that it meets the requirements for paper suction.
(3) Check whether the edges of the stack of paper are contaminated. If there is foreign matter or water on the edge of the paper, or if the paper is cut with a blunt paper-cutting blade, if the edges of the paper are likely to stick together, resulting in difficulty in the suction of paper and empty sheets may appear. Shake the paper properly.
(4) Check whether the air blowing volume is too small to blow the paper edge above, so that the gap between the suction nozzle and the paper surface is uncomfortable and empty, which can be adjusted by adjusting the air blowing volume.
(5) Check if the vacuum suction is insufficient or the suction nozzle is broken or the straw breaks and the air leaks. You can take care to clear the pipe and remove the clogging of the foreign material. Replace the broken rubber nozzle and the air pipe.
(6) Check whether the angle and height of the suction nozzle and the paper stack are appropriate. If there is any discomfort, adjust it as appropriate so that the paper surface is flush with the suction nozzle head and meets the paper stack height required by the suction nozzle.
(7) Check if there is any discomfort in the position or angle of the separation brush or steel sheet. Adjust the brush and steel sheet appropriately according to the degree of paper hardness and hardness.
(8) Check if the air pump is working properly. Check if the suction force of the suction head is even. If the suction force is large or small, it means there is a problem with the air pump and it should be repaired.

3. Two or more paper failures

(1) If the vacuum suction force is too large to cause a double-sheet failure, it should be checked whether the vacuum sucking force is increased due to the large diameter of the rubber suction nozzle, or whether the vacuum suction force of the air pump itself is excessive. For the former, according to the thickness of the paper, choose a suitable rubber suction nozzle or no rubber suction nozzle; and for the latter, should reduce the amount of suction, to achieve the effect of printing paper does not absorb double or multiple sheets.
(2) Double sheet failure caused by insufficient air volume. The reason may be improper valve adjustment or failure of the air pump, resulting in blockage of the air path, cracking of the pipeline, reduction of blowing volume, blowing of some paper on the loose paper pile surface, and causing double or multiple failures. Should be checked one by one to exclude.
(3) The split paper brush and steel sheet do not cause double sheet failure. This may be due to excessive separation between the paper brush and the paper edge, or the length and angle of the steel sheet. The position of the brush and the length and angle of the steel sheet should be adjusted so as to maintain the function of separating paper and loose paper.
(4) The suction nozzle is adjusted too low or the paper table is raised too high to cause a double sheet failure. When the suction nozzle is too low and the distance from the paper stack is too small, double sheets of thin paper are likely to occur; if the paper tray is raised too high, some of the paper on the surface will not be blown loose, resulting in double suction. The distance between the nozzle and the paper table should be properly adjusted, and the speed of the paper table should be increased.
To sum up, as long as the operator strictly implements the production process in daily production and abides by the operating rules, according to the performance of the equipment and the characteristics of the substrate, it is necessary to carry out the necessary maintenance and debugging of the equipment, improve the equipment and The printability of paper can effectively avoid the occurrence of various failures.

Source: China Automation Network