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Adjustment and use of flat paper brush in automatic letterpress printing machine
Flat paper brush is an important part of the automatic letterpress printer. On the one hand, it can prevent the impurities and powder on the paper from falling onto the printing plate or the ink roller and reduce the chance of the printing paste. On the other hand, it can foil the paper in the imprint and make the printed paper flat to the next level. Overprint accuracy, and can avoid printing wrinkles. Whether the paper brush can produce the above-mentioned utility and it is very important to adjust and use it properly and correctly.
1. Structure and Adjustment Method
Flat paper brushes consist of cams, pendulums, rollers, springs, adjusting screws, positioning pin shanks, swing forks, brush shafts, brushes, fixing screws, and base plates.
The working principle is: the swing of the brush is controlled at the leading edge of the paper, that is, the mouth of the printed sheet. After passing through the brush, the brush contacts the paper on the surface of the drum under the control of the cam, so that folding of the edges of the printed sheet can be avoided. The brush bar is mounted on the base plate, and the base plate is fixed on the lower wall plate of the operation surface. When the gradually increasing curved surface of the brush rod control cam comes into contact with the roller on the swing lever, the swing fork swings leftward to rotate the pull fork clockwise, and the brush bar associated with the swing fork moves away. At this time, the embossing roller bites the paper teeth into the brush position, and when the roller bite paper teeth rotates about 20-30 mm, the profile of the decreasing cam diameter enters the rolling surface to set off the paper to achieve the effect of flat paper.
Brush pressure adjustment is an important part of determining flat paper effect. When the pressure is adjusted, the platen presses the printing surface to make contact with the brush in the absence of a printing plate in the platen. The roller is then pressed down by hand and the brush opens. Take two 30-40mm wide strips of paper from both ends of the drum. Relax the pressure on the roller so that the brush sticks to the roller surface. At this time, two pieces of paper are pulled by hand. If there is no obvious sense of resistance, it means that the pressure applied by the brush is appropriate. If the pressure of the flat paper brush is too high, the printing is likely to wrinkle. At this time, the screw should be withdrawn slightly. On the contrary, if the brush pressure is insufficient, it is easy to cause overprinting. In this case, the screw should be screwed in slightly. After the alignment, tighten the lock nut on the screw to prevent loosening. When using the brush, the adjusting handle should be positioned in the middle hole. This avoids shifts due to jitter.
2, should pay attention to the problem
When the flat paper brush is worn and a new brush needs to be replaced, the brush should be trimmed to a medium length with both ends slightly shorter. In this way, when the brush is working, the air between the surface of the impression cylinder and the paper is easily discharged from the middle to both sides, and the printed sheets can be prevented from being scratched and wrinkled.
The correct adjustment and use of the flat paper brush, in addition to the dirty and dragging parts appear dirty and other printing problems. Therefore, in order to ensure that the flat paper brush performs better, the printed sheet does not droop in the drum, and the worn brush should be updated in time. In addition, you should always pay attention to the maintenance of the brush. Apply to the brush that is stained with ink or paper, paper dust, and dusting powder, and apply regular cleaning with gasoline to ensure that the brush is clean. During cleaning, the entire brush device should be removed from the printing press. When disassembling, the printer platen can be moved to the delivery table so that the notch of the roller can be directed against the brush and the two fastening screws can be removed. In this way, the entire brush device can be smoothly removed.
In short, flat paper brush is an important part of the printing press to prevent printing defects and ensure product printing quality. It is very necessary and meaningful to properly adjust and use the flat paper brush and maintain it scientifically and reasonably.