One, double, multiple failures
For the currently widely used pneumatic continuous overlapped paper feed, when two or more sheets of failure occur, the work hours will be lost or the blankets will be damaged. If the weight is heavy, the machine parts will be damaged and the drums will beat. We need to prevent such failures from occurring. . The causes and solutions are as follows:
1. Improper adjustment of paper separation
If the suction of 1 minute paper suction nozzle is too large, adjust the air volume adjustment knob or the regulating valve on the air pump to reduce the suction volume; you can also replace the small suction nozzle rubber ring. The position of the pick-up nozzle is too low, raising the position of the pick-up nozzle.
2 loose paper blowing mouth blowing too much, adjust the air volume adjustment knob or valve on the air pump to reduce the amount of blowing, so that it can blow up 5-10 sheets, less thick paper, thin paper and more. The position of the loose paper mouthpiece is too low, raising the position of the loose paper mouthpiece.
3 The pressure of the paper blowing nozzle is too small, increasing the amount of blowing. The pressure of the paper blowing nozzle is too small to increase the amount of paper pressure.
4 The suction nozzle of the delivery paper is too large, reduce the suction volume or replace the small suction nozzle rubber ring.
5 The paper bristle brush position is too high to stop the paper and lower its position. The paper bristle brush protrudes into the paper tray and the insertion amount is increased.
2. Reasons for paper
1 There is static electricity on the paper, which makes it difficult to move paper. The solution is to install static eliminators, increase indoor humidity, or use antistatic agents.
A. Install static eliminator. The static eliminators used on the printing presses include induction static eliminators, high-frequency high-voltage static eliminators, and high-frequency high-voltage static eliminators. They should be placed near the drum when installed.
B. Increase indoor humidity. The generation of static electricity is related to the relative humidity of the operating environment. When the relative humidity of the workshop is lower than 40%, electrostatic problems are likely to occur. Therefore, when printing, sprinkle some water around the paper stack and the machine, or use an air humidifier to adjust and improve the printing workshop. Relative humidity, to avoid static electricity (usually 20 °C humidity should be maintained at 55% -65%).
C. Condition the paper. When the moisture content of the paper is low, the paper is prone to static electricity. When the paper is charged with static electricity, it is necessary to hang the paper or place the paper stack in a relatively humid environment for a period of time. However, care must be taken to prevent the occurrence of paper ruffles.
2 The ink on the paper is not dry, the upper and lower papers are stuck, and the ink is allowed to dry before being printed on the machine.
3 The paper is not loaded and reload the paper. The paper cutting error is too great, and the paper is trimmed again.
Second, empty fault
In the event of an empty sheet failure, if the machine fails to detect it, the ink that was supposed to be transferred to the paper is transferred to the impression cylinder, which will cause the next dozen or more sheets of paper to be printed on the back, resulting in scrap. The causes of the gap are:
1 minute suction nozzle suction is too small, increase the suction volume or replace the large rubber band. It is also possible to block the airway and repair the airway. The position of the suction nozzle of the paper is too high, the paper cannot be sucked, and the paper suction nozzle is lowered. The paper suction nozzle is not parallel to the paper stack surface, adjust the nozzle angle or use a wooden wedge to lift the paper stack.
2 Blown paper blowing volume is too small, increasing the amount of blowing. Loosen the blowing nozzle position too high or too low and adjust the position of the paper blowing nozzle.
3 Press the brush or the pressure plate into the paper stack too much and adjust it to a suitable position.
4 pressure paper blowing nozzle pressure too much paper to reduce the amount of paper.
Third, failure
Defective sheeting means that the sheet is skewed. The skewed sheet will cause the rules to stop the normal positioning of the sheet and waste man-hours. When the paper feed is skewed, we can see that the edges of the running paper are serrated from the paperboard. The causes of arrogance are:
The inhalation amount of the left and right suction nozzles of the 1 minute paper nozzle is inconsistent, and is generally caused by the blockage of the air passage. The air path can be cleaned. The paper suction nozzle is different from left to right and adjusts its position. The size of the rubber band on the left and right sides of the paper suction nozzle is different. Replace the same size rubber band. The paper suction nozzle is not flexible up and down, remove and repair.
2 The position of the upper and lower platen brushes is inconsistent and they are adjusted to a consistent position.
3 The position of the upper and lower loose paper mouthpieces is inconsistent. Adjust them to the same position.
4 The feeding nozzle is inflexible and removed.
5 The paper stopper is not on the same plane or the working time is incorrect. Adjust the stopper or the paper stopper cam.
6 The two pendulum pressure rollers do not have the same time to adjust the pressure, and adjust the control cam so that the pressure time is the same.
7 There are different elasticities in the feeders. Adjust the tensioner so that the tension of the feeders is the same.
8 The paper feeder itself is skewed, and adjust the paper feed position.
9 The feeding roller is misaligned due to improper positioning of the platen roller or inflexible rotation, adjusted to a suitable position, and regularly filled with a small amount of lubricant.
Fourth, unstable paper feeding
Unsteady paper feeding means that the speed of paper feeding is uneven and it is fast and slow. As soon as the paper is fed, the paper will fall under the front bezel, the paper feed will be slow, and the paper will not be in place. In both cases, overprinting will occur and the product will be scrapped. For this reason, the paper feed speed must be adjusted quickly, and then slowed down for a moment, causing confusion. Many machines have not been solved for this problem for a long time, affecting quality and reducing production. The causes and solutions are as follows:
1 The feed nozzle still sucks after feeding the paper, causing the paper that has entered the feed shaft to be blocked due to the backward pull of the suction nozzle, resulting in a pause. Because the paper is overlapped, the previous sheets of paper are affected at the same time and slow down. In the middle of a stoppage, if the operation of stopping the paper after the air pump is turned off is first adopted, the last few sheets of paper on the paper will have a slight speed due to the influence of no nozzle suction, resulting in unstable paper feeding. There are two solutions:
A. Adjust the front and back movement cams of the paper feeding nozzle, so that when the manual inspection is performed, the paper feeding distance from the suction nozzle to the limit position is about 10 mm, and the paper should be put, and no over-absorption will occur.
B. Plug the air duct of the suction piston. For example, the "Northern" SZ201 type paper feeder adopts a method of blocking the air duct and has a good effect. The procedure is as follows: Remove the piston and fill the tail of the wind slot with copper blocks of 3 to 5 mm. Copper blocks should be firmly welded to prevent accidents.
The paper feed caused by the 2 line belt is not stable.
A. The tape is too loose, tighten the tape, and the tension of each tape should be as consistent as possible.
B. The belt tensioning wheel is in poor condition and is cleaned with kerosene and lubricated.
C. The paperboard will produce resistance to the tape, and remove the dirt on the steel pad of the paperboard to remove the resistance.
D. Use double-layer tapes to avoid jitter due to uneven tape thickness.
3 Feed roller jump (not round), replace the new delivery roller.
4 The gaps between the running parts of the feeders are too large. Check the parts and perform necessary repairs or replacements.
5 clutch accumulation of paper hair, excessive oil, caused by the clutch action is not flexible, did not hang the clutch to the position of the clutch, causing the paper feed suddenly, the clutch can solve the problem.
6 The bearing on the passive roller inside the paper conveying belt is damaged, and it does not turn when turning. It also causes the instability of the paper feeding. During the inspection, the cardboard can be lifted, the cord can be loosened, and the cord can be turned by hand. Replace the bearing to solve the problem.
Fifth, the paper is early or late to the former
The arrival of the paper at the beginning of the positioning of the side profile has not yet reached the front defined bit line, which is called late arrival of the paper. The early arrival of the paper means that the paper feeding machine's feeding time and the time of the preceding rule fall in place, resulting in the paper reaching ahead of the specified time. Pre-specified bit line. Whether the paper is early or late, it will make the rules unable to achieve the normal positioning of the paper, resulting in misprints. The causes and solutions are as follows:
1 The paper feeder's paper feeding time is not properly matched with the drop time of the front gauge. The correct matching time should be when the current gauge falls to the positioning position, the paper's mouth edge distance from the front specified bit line 5 ~ 8mm. For the chain-driven J4105 machine, you can loosen the three fastening screws on the sprocket first, then turn the paper hand wheel to adjust the paper to the right position, and then tighten the three screws; HeidelbergSpeed-Master series It is also possible to adjust the mating time by changing the gear meshing relationship in the feeder box.
2 The paper stack height is lower than the allowable height of the front trim block, and the sent paper is blocked, causing the paper to arrive late. The height of the paper stack should not be lower than the axis of the swing block of the front block, and generally it should be 5~10mm below the front of the front block. This situation can be properly raised Feida; if the paper pile is too high, even higher than the top of the front block, causing the paper to arrive early. At this time, the height of the feeder can be lowered or the wedge can be inserted to reduce the height of the stack. The adjustment requirements are the same as described above.
3 The swinging pressure roller is falling late or worn badly. The pendulum pressure roller should feed the paper at the paper feed nozzle, and it will just fall down and press the paper when it is about to stop the air suction. When the pressure stops, it can feel a certain tension. When the wear is serious, it should be replaced in time.
4 Feida's paper feeding time is too late (as opposed to a swinging pressure roller). Under the premise of correct hem swing time, the feeder's transmission time is adjusted according to its hem time (north PZ4880-01 and Heidelberg's Speed-Master have a relative position in the feeder's transmission box. Sprocket.
The 5 string tension is small, or the pressure of the paper feeding roller is too light, causing the paper to arrive late. On the contrary, it caused the paper to arrive early. The solution is to tension the strap to a suitable degree or adjust the pressure of the delivery roller appropriately.
In the offset printing process, there are many factors that affect the transport of paper. If it is found during the operation that the paper feeding failure occurs, it can be eliminated as described above, which can ensure the smooth production.
