KBA Rapida 104 printing experience
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When the KBA Rapida 104 four-color machine printed a coated paper with a basis weight of 105 g/m2, the paper tail showed severe wrinkles.
From the point of view of the failure phenomenon, it is preliminarily determined that the wrinkles are generated after the first color combination pressure. After analysis, it is known that before the paper reaches the first color group, the unevenness of the tooth decay can not hold the paper, causing the paper to slip in the tooth decay, resulting in uneven surface of the paper, so the first color combination Wrinkles are generated when pressed. Further analysis, which part of the space problem is present. Firstly, based on the transfer paper, the delivery device of the KBA Rapida 104 four-color machine is an intermittent double-discharge roller, followed by a single-row tooth transfer roller, and then the paper enters the printing unit. Jog the machine, enter a few sheets of paper into the molars, try to rub the tail of the paper by hand, and find that there are several fangs in the dent of the paper roller that can't hold the paper. Increase the force of these fangs and adjust them with the same uniformity of force. Reboot and troubleshoot.
Elastic recovery method for lining materials
The lining material inside the blanket cylinder of the offset printing machine, such as felt and worsted wool, loses its elasticity due to long-term pressure. The following treatment methods can be used to restore the original elasticity.
Immerse the old felt and finely woven wool in a washing powder solution with a water temperature of 60 ° C for 15 minutes. After the water is cool, gently rub each felt and worsted wool by hand. If there are inks and other dirt on both sides, try to Rinse thoroughly, then rinse with tap water until it is clean. Gently wring the water and then rinse the clean felt and worsted wool in the sun or dry it in oil drum or round rough wood. Restore elasticity.
When drying, be careful not to fold on the fine wire, which will make the felt and worsted wool produce obvious wrinkles, which is not conducive to the loading of the blanket cylinder. At the same time, the finished products of felt and finely woven wool are rolled into a cylindrical shape as much as possible in the warehouse and workshop collection to prevent wrinkles from folding.
Intuitive sound
When a PZ4650 four-color melter prints a light-coated paper with a basis weight of 65g/m2, the paper has lateral ghosting and wrinkling on the tip of the second color group.
Check the force of the cavities and the condition of the attack pad, and the fixing screws of each roller are not loose. When the maintenance personnel adjusted the force of the impression cylinder to the teeth, the situation improved, but after a while, the fault recovered.
The machine was stopped again to check the open bearing, and no problem was found. However, when the machine was jogged, it was accidentally heard that the tooth was caught and suddenly released and closed. Based on this finding, the maintenance personnel again inspected again and found that the second color group impression cylinder jaw link was displaced to the operation surface, and the open bearing was placed on the wall panel. The reason for the displacement is analyzed. It turns out that the washer and the circlip of the fixed connecting rod end of the transmission surface fall off. Firstly, the connecting rod is pulled to the appropriate position on the driving surface, and then the washer and the circlip are installed, and the spring is turned on again, the printing effect is good, and no ghosting or wrinkling occurs.
Reconstruction of JS2102 Offset Press Roller
JS2102 offset press roller has a high failure rate, and maintenance adjustment is very troublesome. The main failure phenomenon: the fangs are not worn, and the fangs are uneven. When adjusting the fine adjustment of the top wire, it is not the top of the rack or the top of the paper. It is difficult to adjust to the proper position. Cause of the malfunction: The clamp on the dental shaft is ejected by the top wire, and it is just halfway to the seam. Generally, in this case, the factory will replace the new clamp or use the repair welding method to fill the small pit. But in fact, these solutions not only increase the cost of maintenance, but also do not solve the actual problem.
According to several experiments, a very effective method was found. When repairing the roller row, first fold all the clamps, find some φ5.5mm steel balls, and use a drill with a diameter of 5mm to make a round hole at the position where the clamp is pushed out of the pit, and in each clamp A steel ball is placed in the pit, and the steel ball should be half the plane. It is best to apply some butter when loading the steel ball, so that the steel ball will not fall out when installing the bracket clamp, and it can also play a lubricating role.
After the modified roller row, even if the spring is broken, the steel ball will not fall out, so it is safe and reliable. Its greatest advantage is that it extends the life of the roller row.
Monochrome printing machine maintenance
A monochrome printing machine, after the normal maintenance in the off-season, did not start printing for a long time. After that, it printed a batch of two-color mostly flat-screen prints. Because there was no car wash before printing, the ink was printed. When printing, there was a piece of ink about 2cm2 in the middle of the print, which was lighter and lighter. It returned to normal. Starting from the blanket cylinder, it was found that although the ink on the transfer roller was uniform, there was a piece of ink on the ink roller that was not inked and the axial position was the same as that of the print. I felt it smooth when I touched it by hand. It turned out that the oil was dripping on it. Since the car washing operation is too cumbersome, the operator uses the cleaning paste to clean the place where the roller is not inked, and then wipe it with a dry cloth, and the effect is the same as that of the brake.
Experience: When the press is not working for a long time, it should be covered with cardboard or plastic film to prevent dust from falling onto the roller and causing no ink. In addition, care should be taken not to drip the oil on the rollers.
Use dirty paste to remove dirt
Graphic part of the dirty
When extracting the printed sheets during the printing process, it was found that the printed parts of the printed matter were floating (paste). After the machine was stopped, use a damp rag to remove the cleansing paste, wipe off the dirt on the printing plate, and then wipe it with water. Then start printing again. In doing so, not only is the work efficiency low, but also restarting, it will make the ink color of the first dozen prints deeper, and more waste products. In the daily work, the author sums up a method to remove the floating dirt of the printing plate without stopping the machine and ensure the continuity of printing. Specific method: When the printing machine is normally printed, use a damp rag to apply a little cleaning paste, and wipe the corresponding water bucket roller according to the dirty position of the printing plate. The cleaning paste on the water fountain roller is transferred to the chrome roller and the dampening roller. On the plate, the dirty dirt on the plate disappears. In doing so, the effect is very good, and it saves time and effort, and also improves work efficiency.
Non-image part is dirty
If there are inks in the circumferential direction of the two ends or one end of the printing plate, it should be removed in time. One, as the printing progresses, the ink is dirty, and once it spreads into the graphic, it causes waste; second, the ink is transferred to the impression cylinder by the blanket cylinder, and the cleaning impression cylinder is very clean. Hard work. In the past, the ink on the ink fountain roller corresponding to the non-image portion of the printing plate was "broken" or the liner on the non-image portion of the blanket cylinder was cut. The effect of using the above method to remove the dirt is very good, but the amount of the cleaning paste should be increased. When the machine is stopped, it is necessary to check whether the pressure of the printing roller and the dampening roller on the printing plate is correctly adjusted.
Solution to the problem of ink stick in offset printing
In the offset printing process, the ink stick problem sometimes occurs, which directly affects the quality of the printed matter. There are many factors causing the ink stick, but it is mainly caused by improper mechanical adjustment and damage to mechanical parts.
1. Ink rod caused by improper mechanical adjustment
(1) The pressure between the inking roller and the printing plate is too large, exceeding the pressure between the printing plate and the printing plate, causing sliding on the printing plate, especially the two ink rollers which function as ink collecting, which easily cause the ink bar .
(2) The pressure between the inking roller and the inking roller is too large, exceeding the pressure between the printing plate and the printing plate, causing sliding on the printing plate, especially the two ink rollers which function as ink collecting, which easily cause ink Bar.
(3) The surface of the ink roller is aged or the shape is changed, the left and right pressure adjustment is not caused, and the ink roller is caused to jump when the machine is running, causing the ink stick.
(4) The pressure between the plate cylinder and the blanket cylinder is too large, mainly due to the improper use of the plate cylinder or the blanket cylinder lining, causing the pressure to be too large, causing the circumference of the drum to be inconsistent, causing a speed difference and causing the ink stick.
(5) The pressure of the contact type roller is improperly adjusted, which affects the center distance of the roller and the printing pressure, thereby causing the ink stick.
For the above problems, the following solutions can be used.
(1) Replace the ink roller
(2) When adjusting the pressure between the ink roller and the plate cylinder and the ink roller, adjust the data in strict accordance with the machine manual.
(3) Correctly calculate the amount of lining of the roller to ensure that the line speed of the roller surface is consistent under a small printing pressure, and the graphic transfer effect is good.
2. Ink rod caused by mechanical component damage
(1) The roller gear is worn and the line speed between the rollers cannot be kept consistent, and a ink stick is generated.
(2) The roller bearing wears after a long time of use, and a rubber rod is generated.
Solution: Replace worn parts.