When KBA Rapida 104 four-color machine printed coated paper with a basis weight of 105g / m2, serious wrinkles appeared at the end of the paper.

From the fault phenomenon, it is preliminarily determined that wrinkles are generated after the first color combination is pressed. After analysis, before the paper enters the rule to reach the first color group, the gripping force of the gripper is uneven, and the gripper cannot hold the paper, causing the paper to slide in the gripper, causing the surface of the paper to be uneven, so it is combined in the first color Wrinkles occur when pressed. Further analysis, which part of the space problem lies. First of all, the search is based on the paper transfer teeth. The paper transfer device of KBA Rapida 104 four-color machine is an intermittent double-row tooth cylinder, followed by a single-row tooth transfer cylinder, and then the paper enters the printing unit. Jog the machine, input a few sheets of paper into the gripper, try to pull the tail of the paper by hand, and find that there are several grippers at the transfer roller gripper. Increase the gripping power of these grippers, and adjust the gripping force according to the standard. Restart and troubleshoot.

Elastic recovery method of lining material

The lining materials inside the rubber cylinder of the offset printing machine, such as felt and worsted wool, will lose their elasticity due to long-term rolling. The following treatment methods can be used to restore their original elasticity.

Immerse the old felt and fine-knitted wool in a washing powder solution at a water temperature of 60 ° C for 15 minutes. After cooling the water, rub each felt and worsted wool lightly by hand. Scrub and wash, then rinse with tap water until it is clean, gently wring the water, and then rinse the rinsed felt and worsted wool in the sun or dry it in an oil drum or round rough wood. Restore flexibility.

When drying, be careful not to fold it on the thin iron wire, which will easily cause obvious wrinkles on the felt and worsted wool, which is not conducive to the installation of the rubber roller. 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 to prevent folding and wrinkling.

Unusual sound inspiration

When a PZ4650 four-color glue machine of our factory printed light-coated paper with a basis weight of 65g / m2, the paper appeared horizontal ghosting and wrinkles on the trailing part of the transmission surface of the second color group.

Check the gripping force of the gripper and the condition of the tapping pad. The fixing screws of the rollers are not loose. When the maintenance staff adjusted the gripping force of the impression cylinder's gripping teeth uniformly, the situation improved, but the fault recovered after a period of time.

Stop the machine again to check the open bearing. No problem was found, but when jogging the machine, you can hear the sound of the gripper being suddenly released and closed. Based on this finding, the maintenance staff carefully checked again and found that the gripping rods of the impression cylinder of the second color group were all displaced toward the operating surface, and the open bearing was pressed against the wallboard. The reason for the displacement analysis is that the washer and circlip of the fixed connecting rod end of the transmission surface fall off. First pull the connecting rod to the appropriate position to the transmission surface, and then install the washer and circlip, restart the machine, the printing effect is good, and there is no ghosting and wrinkles.

Modification of JS2102 offset printing machine cylinder row

JS2102 type offset printing machine has a high failure rate of cylinder row, and maintenance and adjustment are very troublesome. Main failure phenomenon: the gripping force has not been even before the gripper has been worn. When adjusting the fine-adjusting top wire, it is difficult to adjust to the proper position because it can not stand the tooth frame or the paper. Cause of failure: The clamp on the dental shaft is pushed out of a pit by the jacking screw, and it is exactly halfway down the riding seam. Generally encountered this situation, the factory will replace the new clamp or use repair welding to fill the small pit. But in fact, these solutions not only increase the maintenance cost, but also can not solve the actual problem.

According to many experiments, the author found a very effective method. When servicing the roller row, first fold down all the clamps, find some φ5.5mm steel balls, punch a round pit with a drill of 5mm in diameter at the position where the clamp is ejected, Put a steel ball in the pit, the steel ball should be half higher than the plane. It is best to apply some butter when installing the steel ball, so that the steel ball is not easy to fall out when installing the bracket, and it can also play a lubricating role.

After the transformation, even if the tooth spring is broken, the steel ball will not fall out, so it is safe and reliable. The biggest advantage is that it extends the service life of the roller row.

Maintenance of monochrome printing machine

A single-color printing machine in our factory did not start printing for a long time after the maintenance and adjustment were normal in the off-season. Afterwards, it printed a batch of two-color prints, most of which were flat screens. Because the ink was printed without car washing before printing, during printing, there was a piece of ink about 2cm2 in the middle of the print that became lighter and lighter. After the printing speed was reduced, the ink color Normal again. Starting from the rubber cylinder, it was found that although the ink on the ink 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 the printed product. It feels smooth when touched by hand, it turns out that the engine oil dripped on it. Because the car washing operation was too troublesome, the operator used a plate-cleaning paste to clean the place where the roller was not inked, and then wiped it clean with a dry cloth, and found that the effect was the same as the Xian car.

Experience: When the printer is not working for a long time, it should be covered with cardboard or plastic film to prevent dust from falling onto the rollers and causing no ink. In addition, be careful not to drip oil on the rollers during maintenance.

Cleverly use cleansing 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 dirty (paste). After stopping, use a damp cloth to dip the cleaning paste, wipe off the dirt on the printing plate, and wipe it again with clean water. , And then start printing. In doing so, not only will the work efficiency be low, but also the restart, it will also make the ink color of the previous dozens of prints darker, and there will be more waste products. The author summarizes a method in daily work, which can remove the scum of the printing plate without stopping the machine to ensure the continuity of printing. Specific method: When the printing machine is printing normally, use a damp cloth to dip a little cleaning paste, and wipe the corresponding water bucket roller according to the dirty position of the printing plate. On the printing plate, the floating dirt on the printing plate immediately disappeared. In doing so, the effect is very good, and saves time and effort, and also improves work efficiency.

Non-graphic part of the dirty

If the ink is dirty on both sides of the printing plate or on the non-graphic part of one end, it should also be removed in time. On the one hand, as the printing progresses, there is a possibility that the ink stain will expand. Once it spreads into the picture and text, it will cause waste products; on the other hand, the ink stain will be transferred to the impression cylinder via the rubber cylinder. Strenuous. The previous method was to "snip off" the ink on the ink fountain roller corresponding to the non-graphic part of the printing plate or to cut off the liner on the non-graphic part of the rubber cylinder. The effect of applying the above method to remove dirt is very good, but the amount of cleaning paste should be increased. When the machine is stopped, it is necessary to check whether the pressure of the inking roller and dampening roller on the printing plate is adjusted correctly.

Solving the problem of ink stick in offset printing

In the offset printing process, ink stick problems occur from time to time, which directly affects the printing quality. There are many factors causing ink sticks, but they are mainly caused by improper mechanical adjustment and damage to mechanical parts.

1. Ink bars caused by improper mechanical adjustment

(1) The pressure between the inking roller and the printing plate is too large, exceeding the pressure with the printing plate, causing slippage on the printing plate, especially the two ink rollers that play the role of ink collection, which can easily cause ink sticks. .

(2) The pressure between the inking roller and the inking roller is too large and exceeds the pressure with the printing plate, causing slippage on the printing plate, especially the two ink rollers that play the role of ink collection, which can easily cause ink Bar.

(3) The surface of the ink roller is aging or the shape changes, and the left and right pressure is not adjusted. When the machine is running, the ink roller jumps and the ink stick is caused.

(4) The excessive pressure between the plate cylinder and the rubber cylinder is mainly due to the improper use of the plate cylinder or rubber cylinder liner, which causes excessive pressure, makes the circumference of the cylinder inconsistent, produces a speed difference, and causes ink sticks.

(5) Improper adjustment of the pressure of the contact roller pillow affects the center distance of the cylinder and the printing pressure, thereby causing ink sticks.

For the above problems, the following solutions can be adopted.

(1) Replace the ink roller

(2) When adjusting the pressure between the inking roller, the plate cylinder, and the inking roller, strictly follow the data in the machine manual.

(3) Calculate the amount of drum lining correctly to ensure that the linear speed of the drum surface is consistent under a small printing pressure, and the effect of image and text transfer is good.

2. Ink bars caused by damage to mechanical components

(1) The roller gear is worn and the linear speed between the rollers cannot be kept the same, resulting in ink sticks.

(2) The roller bearing wears out after being used for a long time, resulting in ink sticks.

Solution: replace worn parts.

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