【Printing machine repair】How to do printing machine failure Printing machine failure repair
What to do if the printing machine fails
There are four main common faults in printing presses: paper breakage, water, ink and embossing troubleshooting, overprinting part of the fault, folding part of the fault analysis and elimination.
1．Paper Break Failure
Paper breakage is a major headache, mainly for the following reasons:
(1) edge crack, tight edge, edge bruising or side sticky glue. Paper roll tight side or side sticky with glue when the performance of the paper belt is easy to break, affecting the normal paper supply. Such phenomena can be found in the water brush wet tight side or sticky glue side, the failure is then removed.
(2) the paper roll itself cylinder core is not round. The operator can determine by experience whether the eccentricity of the core is too large, and depending on the situation, timely change the paper or notify the machine administrator to reduce the speed of operation to avoid.
(3) lifting speed is too fast or tension is too large. The paper has a tension limit, when increasing the tension should be as far away from the limit tension. At high speed, a very small change can also produce very large stress, and lead to paper breakage.
(4) The paper guide roller arbor is loose, the level and parallelism is not allowed, the arbor or bearing is worn. For the use of a certain number of years of machine, should pay sufficient attention to the maintenance personnel and operators should check the working condition of the paper guide roller in a timely manner.
(5) too much ink scale deposited on the paper guide roller. After a long time on, the deposition of ink scale increases the radius of the rollers, so that the tension also increases. When the tension reaches the limit value, the machine breaks the paper knife will cut off the paper protectively. Therefore, the ink scale deposited on the paper guide roller should be removed in time.
2．Watering, inking and embossing failure
（1）Water supply section
Water supply devices can generally be divided into two kinds of indirect water supply and direct water supply. Regardless of which way the water supply, the purpose is to fully moisten the printing plate, to maintain a balance of water and ink. A variety of specific manifestations of failure are: the amount of water will make the ink loss of luster, gray and light, ink is not full, serious ink emulsification; the amount of water is small, the printing plate can not be fully moistened, resulting in graphic deformation, blurred and other phenomena. Specific exclusion methods can be adjusted according to the structure of the water supply mechanism, the function of the components.
Such as by checking the water bucket baffle motor or nozzle solenoid valve work, water transfer roller, series of water roller, against the pressure between the plate roller and the plate roller is normal to troubleshoot, it should be noted that the pressure between the two ends of the water roller must be adjusted to a balanced position. Normally, the water roller and water bucket nozzle should be cleaned in time to check the pressure between the water rollers.
（2）Ink supply section
The ink supply mechanism is composed of ink hopper roller, ink transfer roller, string ink roller and ink roller against the plate. Its common failures are: insufficient ink supply, large ink supply, unstable ink supply, etc. The above faults can be eliminated by checking the working condition of the ink hopper roller and ink nail and whether the pressure between each ink roller is normal. When adjusting the ink roller, it should be adjusted to test whether the balance of each rubber roller is consistent, and at the same time must ensure that the pressure of the ink roller against the plate is moderate, the ink leveling roller and the ink roller to collect ink with a good match, to keep the printing plate ink absorption evenly, to avoid to the maximum extent possible the inconsistency of the ink color before and after the prints, and carefully check whether the surface of the rubber roller against the plate is flat and clean, there are no big hard injuries such as indentation, scratches or usually bad adjustment of the ink rubber caused by local film, crystallization phenomenon. As the temperature difference between winter and summer is big, the pressure can be increased in winter and reduced in summer.
Imprinting part is the core part of the printing unit, but also the most accurately designed and manufactured part, the general manufacturers do not allow users to adjust the pressure and other machine parts. Printing pressure is an important factor in the printing process to complete the transfer of ink, moderate printing pressure is the printed page, text, graphics clear and clean, the text is not deformed, the ink color is uniform and reliable guarantee. Failure phenomenon mainly ink faint, dot unclear, text deformation, the reason is that the ink transfer is not sufficient, are due to the loss of elasticity of the blanket or lining is too small, as long as the replacement of new blanket or appropriate increase the thickness of the lining can be ruled out.
3．Troubleshooting the overprinting part
Many factors affecting the registration of color prints, paper, plate making, fountain solution, printing processes, equipment conditions and other aspects of the various printing processes involved may have an impact on the registration. Here is a brief analysis of some common register failures, mainly from a mechanical point of view.
（1）Factors affecting the stability of paper tension
The main factors affecting the stability of paper tension are: paper frame, three rollers (infeed), variable speed rollers (PIV) and other tension adjustment mechanism and other guide rollers, pulling paper roller working conditions. Tension adjustment mechanism of the tension adjustment is not appropriate, or all kinds of roller parallelism, level deviation is large, or the paper frame brake wear, roller bearing wear and other reasons will lead to unstable tension, thus causing inaccurate overprinting.
（2）Factors affecting the accurate transfer of graphics
The printing unit as a direct printing part of the precise transfer of graphics, any mechanical deviation will affect the registration of the print. Its failure is mainly caused by the roller bearing wear, clutch pressure linkage mechanism of the copper sleeve or bearing serious wear, the plate mouth pin loose off or improper installation, register adjustment mechanism parts wear, transmission parts wear, potentiometer failure, etc.. Although these failures are not common, but in the basic exclusion of the causes of tension factors, should also carefully check the mechanical deviation of these parts.
4．Folding part failure analysis and troubleshooting
The most common failures exhibited by the folding department are blockages, which can be caused by many factors. We have analyzed the causes of blocking in Roland and Gauss folding machines, and the main points are as follows:
（1）Folding roller on the rubber strip used for too long or aging, resulting in the rubber strip loss of elasticity or knife slit is too wide, too deep, thus causing the newspaper cutting constantly, several newspapers together at the flower wheel is easy to block. By replacing the new rubber strip, the problem can be solved.
(2) cutting roller cutting knife wear or installation of cutting knife height is not in place, resulting in high-speed operation of the cutting knife cut newspaper and caused by blocking the newspaper. The treatment method is generally by raising the knife frame, that is, adding a knife pad under the knife frame.
(3) needle, folding knife, bite knife serious wear, or its corresponding cam roller bearing jammed, or its corresponding torsion spring broken, will lead to folding not in place and cause blockage. Through careful inspection of these parts, depending on the situation to adjust or replace the corresponding parts after the failure can be resolved.
(4) The cutting knife just cut to the automatic paper with the adhesive tape and failed to cut it off caused by the blockage. This phenomenon is generally rare, and there is no suitable treatment.
(5) the paper itself is too wet or water open too much, resulting in cutting is not easy to cut off caused by blocking the newspaper. If the paper itself is too wet, replace the paper roll; such as the water is too large, the timely closure of the small amount of water.
(6) the folding roller diameter adjustment is not appropriate or into the folding department before the tension is not properly adjusted, resulting in pulling the newspaper or pinhole pulling broken, may also cause blockage. The treatment method is to check whether the folding roller diameter adjustment is appropriate and adjust according to the situation: check whether the variable speed roller tension adjustment is appropriate, whether the pressure roller on the variable speed roller is too tight or too loose and other measures to be solved.
Now is not feel that some common failures of the printing machine is very good to solve, but they really can not be sure of the problem or have to ask professional maintenance personnel. The next issue to introduce you to the maintenance of printing machines and maintenance, so that the chances of failure to occur to a minimum or even do not occur is the king.