Analysis and Elimination of Common Faults in Web Offset Press

The common faults of web offset presses can be divided into three types: some paper faults, some printing faults, and some folding faults. To troubleshoot, we must carefully read the random instructions and mechanical schematics, master the printing performance and mechanical properties of the machine, fully understand the structure and use of the various parts of the machine, only to achieve these points can have a correct fault After analysis, make corrective measures.

First, the paper on the common faults and troubleshooting

The paper section is the whole process of guaranteeing a smooth, uniform supply of paper to the printing section. The common faults are: paper folds, and the tape is tight. Analysis of the above failures is mainly due to the quality problems of the paper tube, but in order to save raw materials, the failure can be eliminated by adjusting the guide roller and magnetic powder braking method. If the effect is not obvious, the direction of the paper roll movement can also be changed to eliminate such failures. . When the paper roll is tightly edged, it shows that the paper tape is easily broken, affecting the normal paper supply, and it is found that such phenomenon can be wetted on the tight side with water and the failure can be eliminated.

Second, printing unit common breakdown and elimination

The printing unit is the main part of the offset printing rotary press. Whether or not the printing unit operates normally affects the key part of the product quality directly. The common faults of the printing unit can be divided into three categories: partial failure of the water supply; failure of the ink supply section; and partial failure of the imprint.

1. Analysis and elimination of common failures in water supply

Water supply equipment can be divided into: indirect water supply and direct water supply. Indirect water supply is the use of brush to atomize water to achieve the purpose of water supply. Direct water supply refers to the transfer of water through water rollers to achieve the purpose of water supply. No matter which method is adopted for water supply, the purpose is to make full use of the printing plate. Wet to maintain the ink balance.

(1) Analysis and elimination of common failures of indirect water supply

The composition of the indirect water supply part: The indirect water supply part consists of a water fountain roller, a brush roller, a string of water rollers, and a water roller.

The common faults of indirect water supply are: the water supply is too large or too small, and the amount of water supply at the end of the printing plate is large or small, that is, the water supply volume at the two ends of the printing plate is inconsistent. The above problems will directly affect the normal operation of the machine. The specific manifestations of the various failures are: the amount of water will make the ink tarnish, dark and dull, and the ink will not be full. In severe cases, ink emulsification will occur. When the amount of water is too small, the printing plate can not be fully wetted, resulting in graphic distortion, unclear, etc. The specific elimination method can be adjusted according to the structure of the water supply mechanism and the functions of each component. The brush roller and string water roller in the water supply part are fixed and not adjustable, while the water fountain roller and the plate water roller are adjustable, the depth of the water fountain roller in the sink is large, the water supply is large, and the depth is small The water supply is also small. The depth of the fountain roller in the sink is controlled by the adjustable eccentricity of the two sides of the fountain roller. According to this feature, the water supply of the printing plate can be properly adjusted. The gap between the plate roller and the chain roller is adjusted by the plate roller. The gap between the roller and the roller must not be too large or too small. The oversize cannot be fully transferred. Too small will cause a part of the water to be squeezed out. Fail to reach the purpose of transfer. The gap between the plate water roller and the string water roller is consistent and balanced. 15 wire steel can be used to adjust.

(2) Analysis and elimination of common faults in direct water supply institutions

The direct water supply mechanism consists of a water fountain roller, a water transfer roller, a string of water rollers, and a water roller.

Common faults and the indirect water supply mechanism are basically the same, the exclusion method is to adjust the pressure between the transfer roller and the roller roller, the string of water rollers to eliminate, the pressure must be adjusted to the balance position of the water roller, this water supply In general, water rollers are used in the mechanism, and the sink should be cleaned frequently. The pressure between the water rollers should be checked frequently because the water pressure between the water rollers will change after the new water roller is used for a period of time. There will be changes, and with these points in hand, the failure of the water supply will be ruled out.

2, the common part of the ink supply troubleshooting

The ink supply mechanism is composed of an ink fountain roller, an ink transfer roller, an ink roller, and an ink roller.

Failures include insufficient ink supply, large ink supply, unstable ink supply, etc. The analysis of the above failures is due to the fact that the pressure between the ink rollers does not meet the requirements. Remedy: 15 wire steel can be used to adjust the pressure between the ink roller, requiring pressure balance, due to the large temperature difference between winter and summer, adjust the winter may be appropriate to increase the pressure, the summer can be appropriately reduced pressure.

3, the printing part of the troubleshooting

The embossed part is the core part of the printing unit, and it is also the most precise part of the design and manufacture. Generally, it cannot adjust the pressure and other mechanical parts. Faults are dark ink, network points are not clear, lack of hair transfer broken ink is broken, are due to loss of elastic rubber or bag is too small, as long as the replacement of new rubber or the appropriate increase in the thickness of the bag can be ruled out.

Third, the fault analysis and exclusion unit

Folding unit is an integral part of each part that depends on each other and depends on each other. The problem of one part will affect the normal operation of the whole machine. To eliminate the fault, we must understand the performance of each part, the law of movement and the role it plays. Observe and analyze carefully the failures that occurred, and then decide what measures should be taken to eliminate them. Remember not to analyze the faults that have occurred, and to eliminate them if they are not observed. For some faults, it is a problem that occurs in the next process. In fact, it is the problem of the previous process. If the fault is not observed or analyzed, faults will occur. It is difficult to rule out. such as:

The fault caused by the improper adjustment of the parts is due to the performance of the parts, the movement law, and the unclear structure. The fault is usually caused by the folding not conforming to the quality requirements, the tape is damaged, the movement time of the steel needle changes, and the folding knife and the clamping plate cannot Well coordinated, 16K folding knife time changes, etc. These failures are all caused by the mechanical rules of motion. The main elimination method changes the exercise time. The exercise time is generally controlled by eccentricity, and the eccentric high point can be changed to eliminate these failures.

Failure of the machine wear: The failure of the machine wear is due to insufficient refueling of the high-speed movement parts, the mechanical parts can not be fully lubricated, the wear of the parts is accelerated, and the service life is shortened. The normal wear of the parts is not replaced in time.

Failure of mechanical damage

Mechanical damage is generally due to the service life has reached the end of life, or improper operation, the machine movement when there is abnormal sound, the machine can not work, the parts do not work, etc., mechanical damage troubleshooting is mainly to replace or repair Mechanical failure can be ruled out.