Maintenance of Paper Path for Offset Machine Maintenance (2)

5. Transfer cardboard, finger sheet tape and press frame

The function of the paper feeding board, the paper feeding belt and the paper pressing frame is to pass the paper flat to the rules. The paperboard is made of useful steel plates, as long as the flatness can meet the requirements. For paperboard made of wooden boards, due to its ability to resist deformation and the ability to adapt to the environment, it is not appropriate to put heavy things on the paperboard or place it in a place where the temperature is extremely high or the humidity is extremely low. The thickness of the paper feeding tape should be uniform so that the linear velocity of the surface can be uniform. Cloth should not be too loose, otherwise it will slide on the paperboard; should not be too tight, or wear too fast. After installation, 3cm should be lifted by hand. The function of the paper press frame is to make the paper surface flat against the paper roll. This frame must always be in a state, otherwise the paper cannot remain flat on the paperboard, causing printing problems. In addition, the working status of the brush, paper reed, and platen on the press frame should also be checked frequently to see if they can play their due role.

6. Preregulation and lateral appearance

The front and side gauges are the two key parts of the paper and must ensure that they are always in good working condition. The former regulations rely on the front regulation cap, but the former regulation cap will wear out after a period of time, so it should be replaced after a long time. The flexibility and accuracy of the former regulation are the guarantees of the former regulatory position, and therefore it is necessary to frequently refuel or lubricate. The side guide pulls the paper against a friction wheel or a friction plate. The size of the pull force is related to the size of the spring force. The spring will fatigue after working at the celebration time, so check the working condition of the spring regularly. The out-of-roundness of the pull-out roller should also be given more attention, otherwise there will be no pull phenomenon when pulled. The work of the lateral gauge is driven by the power of the front gauge. It is not appropriate to laterally adjust the lateral gauge when the machine is in operation. When the regulations are moved to a new location, they must be locked. Otherwise, they will jump during the work process, resulting in inaccurate positioning. The surface of the rules should be kept clean, otherwise it will affect the accuracy of the specified position, and the surface of the regulatory plate is also not allowed to place objects with heavy weights, otherwise it will cause deformation. As a result, the surface of the paper is uneven, and wrinkles may occur during printing. Once it is found that its deformation should be corrected in time.

7. Hand paper teeth

Paper handing plays a decisive role in the paper path. Its work directly affects the accuracy of paper delivery. First of all, it must be hand-matched. This is the primary condition for ensuring that the paper is flat and forward. The pads may wear or collapse due to impact or other reasons. This requires the operator to constantly check his working condition. Secondly, the bite force should be uniform, otherwise some tooth pads will have large forces and some will have less force. The tooth pad with large force is prone to collapse phenomenon. From the perspective of transferring the paper, the bite force can only hold the paper and convey it forward. Under this premise, the smaller the bite force, the better. Biting force is small, the impact of opening and closing teeth is also small, which is conducive to the smooth transfer of paper, which is extremely important to ensure the quality of printed products. Because the paper feeding and paper feeding times of the paper-feeding teeth are extremely short, they are required to be flexible and stable. Therefore, the grease inside the shaft should be periodically replaced. In addition, the lubrication of the driven delivery circuit must also be guaranteed. Pay attention to the working condition of the open teeth and open the ball to be flexible. If it does not turn, it may cause the open teeth cam or open bearing to wear. The main cause of open ball wear is the accumulation of impurities such as paper powder in the bearing. There is a pin connection between the open oscillating rod and the feed shaft. If the pin is misaligned, the transfer accuracy is destroyed. From this point of view, the impact force is also required to be as small as possible.

8. Front roller

The difference between the front transfer roller and the transfer paper is that the transfer process is performed completely in a relatively stationary state. The requirements for its teeth and open teeth are the same as above.

9. Impression roller

The impression cylinder is one of the most important components in the paper path. During the printing process, the paper cannot slide within its row, which requires its bite force to be so large that the paper cannot slide. Another factor that makes the paper unslidable is the friction coefficient of the pad, and the greater the coefficient of friction, the less likely the paper will slide. Increasing the coefficient of friction is much more beneficial than increasing the pressure of the die because it does not increase the impact of the open and close teeth. Therefore, if it is found that the friction surface of the tooth pad is damaged, it should be promptly repaired, and the pressure of the tooth chip must not be increased blindly. The requirements for open uranium and open teeth of the impression cylinder are the same as above, but the requirements are more stringent, because its force is much greater than the above. The post-transfer roller is involved in the printing of the second half of the process, so its requirements should be the same as the impression cylinder. The difference between the transfer roller and the impression roller is that the surface should be equipped with anti-grant dirty device. After the anti-fouling device has been used for a period of time, the surface area of ​​the ink will increase, but it will bring about dirt. Therefore, if any dirt is found, clean the ink on the dirty cloth. If it still does not work, you need to replace it.

10. Borrowing roller

The diameter roller only plays the role of the middle transfer. The key to its demand is the symmetry of its two tooth rows. If the two sets of teeth are asymmetrical, the transport of the paper is unstable. One sheet is fast and one sheet is slow. Be sure to check the symmetry carefully when overhauling. Another thing to note is the balance, because the drum is large, and careful balancing is needed. When overhauling, you should carefully check its balance accuracy. Check the gear on both sides of the roller when it is removed, and use hand or other tools to push the roller to rotate. If it stops at any position, the accuracy of the static balance can meet the requirements. Since the speed of the printing press is relatively low, dynamic balance detection is not normally performed.

11. Front roller drum II

The maintenance of the front transfer roller II and the impression roller II is the same as the previous one.

12. Take-up roller

The role of the delivery roller is to transfer the printed sheet from the impression cylinder to the delivery chain. The same as the delivery roller and the rear transfer roller is equipped with dirty road protection devices. The other thing that is the same is that both rollers may be involved in the printing process. The difference between them is that one is to bite paper by their own teeth and the other is to bite paper by chain. If the delivery time is inconsistent, there is a possibility that the printed product will be torn or may not be removed. Therefore, during maintenance, the consistency of the mouthpiece should be carefully checked. You can use the ruler to measure the size of the mouth piece by piece. The inconsistency should be adjusted in time. Because the tooth pad of the chain line is liable to cause a change in position due to the opening and closing of the teeth, it is also necessary to check whether the position of the tooth pad is the same during the inspection. The inconsistency should be reset and the wear should be promptly replaced. The lubrication environment of the chain is relatively poor, but it is not lubricating. Therefore, the chain should be scrubbed periodically to prevent the oil from drying up and accelerating the wear of the chain. The degree of tightness of the chain should also be regularly tested, too loose and easy to pull the paper unstable, too fast and easy to cause the chain to wear quickly, generally by hand to increase 4-5cm is appropriate.

13. Planer

The paper feeder is used to level sheets. The leveling process is achieved through the principle of negative pressure, which requires the unobstructed heating hole, and should be regularly checked and cleaned. However, it is best not to use a paper hand cleaner for reverse printing, because it may cause dirt on the side of the paper that is in contact with the paper feeder.

14. Anti-fouling device

The anti-fouling device is to prevent the printed product from colliding with other components at the delivery portion. It uses the principle of air cushion, but it can also be used to prevent the road from winning. When using air cushions to prevent dirt, care must be taken to ensure that the air cushions must be formed below the printed sheets and that they should be large enough. Anti-fouling devices look simple, but care must not be taken. If it is not used properly, the printed product may be at a loss. The powder spraying device is mainly used to prevent sticking of the printed sheets. The basic requirement for the powder spraying device is uniform spraying, which requires that the powder channels are unblocked. The first is that the hole in the powder nozzle should be unblocked. If it is not, use a thin wire to pass through. Followed by the smooth flow of gas. If the amount of gas is insufficient, the dusting speed will not go up. Airway blockage is often associated with dampness, so it is best to use dry powder. Before going to work everyday, try to remove the remaining powder from the powder road. In the use of powder, it should also pay attention to whether there are large particles in the middle, this kind of particles may also cause the road blockage. If there are large particles, try to crush it and put it in again. The dusting nozzle of the powder spraying device should face the surface of the paper, so as to effectively play the role of powder, otherwise it is possible to blow the particles around, which will not only cause the chain to wear, but also affect the health of the operator. The dusting area is opposite to the effective printing area on the paper, and the size of the dusting area can be adjusted. The lateral size can be controlled by closing the powder nozzle, and its longitudinal size can be controlled by adjusting the position of the dusting cam. The amount of dusting is limited to the minimum number of wins. Too large is not good for drying, and it is disadvantageous for subsequent printing. When the size of ink is large, the place with large amount of ink is easy to get dirty.

15. Brake roller

Brake roller is used to reduce the part of the speed, it by absorbing the air below the sheet to form a negative pressure, increase the resistance of the direction of the printing sheet to achieve the purpose of deceleration. Therefore, the suction circuit of the brake roller must be unblocked. If it is not smooth, it must be repaired in time. However, in the reverse printing, it is better not to use a brake roller, and the deceleration can be achieved through other deceleration mechanisms. Because the use of brake roller may cause back dirt. Nowadays, the brake roller of some printing machines also has a blowing function, which means that the suction function is used when printing on one side, and the blowing function is used when printing on both sides.

16. Fan

The fan is used to pressurize and decelerate the printed sheet. The greater the wind power of the fan, the more likely it is that the fan will spread to the surroundings. From this point of view, the smaller the speed of the fan, the better. When the printing is turned on, the fans on both sides can be used, which is harmful and unprofitable (difficulties brought to the brake roller).

17. Open teeth

The open plate is used to control the release of sheets by the key row sooner or later. Although the open teeth frequently encounter the open tooth bearing of the suction paper key row, it does not need to be lubricated, because once it is worn, it can be compensated by changing the position of the open tooth plate. In addition, if the oil is lubricated, the wear of the open jaws will be accelerated due to sludge formation.

18. Papermaking mechanism

The front trimming mechanism and the side trimming mechanism are used to pick up the printed sheets to facilitate stacking and subsequent operation of printed sheets. They should be flexible in their actions and should be lubricated regularly.

19. Delivery table

For the maintenance of the delivery table, see Paper Feeder. However, compared with the paper-feeding table, the smoothness of its work is poor, because its drop inertia increases, so some printers use a brake to reduce inertia. As the paper table rises, the inertia decreases and the work is smooth.