How to troubleshoot common electrical problems in web offset presses

The common faults of web offset presses can be divided into three categories: faults in the upper paper section, faults in the printing department, and faults in the folding section. To troubleshoot, you must read the random instructions and mechanical schematics carefully, grasp the machine's printing capabilities and mechanical capabilities, and fully understand the structure and use of the various components of the machine, only to achieve these points can have an accurate fault After the analysis, make accurate exclusion measures.

First, the common faults and exclusion of the paper sector

The paper department is the whole process of guaranteeing a smooth and uniform supply of paper to the printing department. The common faults are: paper folds, and the tape is tight. Analysis of the above failures is mainly due to the existence of quality problems in the paper tube, but in order to save raw materials, problems can be solved by adjusting the guide roller and magnetic powder braking method. If the effect is not significant, 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 department of the offset printing rotary printing machine, and whether the printing unit operates normally directly affects the hinge department of product quality. The common faults of the printing unit can be divided into three types: failure of the water supply department; failure of the ink supply department; failure of the imprinting department.

1. Analysis and elimination of common faults in the water supply department

Water supply equipment can be divided into: indirect water supply and direct water supply. The indirect water supply uses the brush to atomize the water to achieve the purpose of water supply. Direct water supply refers to the transfer of water through the water roller to achieve the purpose of water supply. No matter which method is adopted for water supply, the purpose is to fully apply the printing plate. Moisture maintains ink and water balance.

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

The composition of the indirect water supply department: The indirect water supply department 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 quantity at both ends of the printing plate is inconsistent. The above problems are caused by various problems that directly affect the normal operation of the machine. The detailed manifestations of the various faults are: the amount of water will be uneven to the general meeting of the tarnished ink, gray and matt, ink is not full, severe ink emulsification will occur. When the amount of water is too small, the printing plate can not be fully wet, resulting in graphic distortion, ambiguity and other phenomena. The detailed exclusion method can be adjusted according to the structure of the water supply mechanism and the function of each component. In the water supply department, the brush roller and the string water roller are fixed and not adjustable, while the fountain roller and the reel water roller are adjustable, the depth of the water fountain roller is large in the water tank, and the water supply volume is large and the depth is small The water supply volume is also small. The depth of the water fountain roller in the water tank is controlled by two adjustable eccentricities of the water fountain roller. According to this feature, the water supply of the printing plate can be adjusted appropriately. The gap between the plate roller and the string roller is adjusted by the plate roller. The gap between the roller and the roller cannot be too large or too small. The oversize can not be fully transferred. If the size is too small, the water in one part will be squeezed. The fall does not reach the purpose of the 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 influent water supply institutions are basically the same failures, the exclusion method is to adjust the pressure between the water transfer roller and water roller roller, skewer water roller to eliminate, the pressure must be adjusted to the balance position of the water roller, this kind of The water supply mechanism generally uses water rollers, and the sink should be cleaned frequently. The pressure between the water rollers should be checked frequently for changing the water roller. Due to the change in pressure between the water rollers after the new water roller is used for a period of time, the water pressure changes. The amount of water has also changed, and with these points in mind, the failure of the water supply department will be ruled out.