Imported rotary offset press common fault handling and maintenance

Since the 1990s, China’s newspaper industry has maintained a high growth rate. “Out of the morning papers and good newspapers” has gradually become one of the magic weapons for the newspaper industry system in the fierce market competition. Therefore, the demand for large and medium-sized import rotary offset presses has been increasing. The quantity has also been expanding, and the high-quality, high-speed, and highly-automated "three-high" requirements have been put forward for imported printing machinery. Major newspaper groups have made huge investments to import advanced rotary offset printing equipment from Europe, America and other countries. In the past decade or so, the Hangzhou Daily Newspaper Group has developed from the first edition of the early 1990s to the existing Four Reports (in which the city Express has reached 80 editions at most one day). The main printing equipment of the Printing Center also developed from the domestic 787 minicomputer in the early 1990s to Roland UNISET in the mid-1990s, the Goss Global 70 in the early 20th century, and even the upcoming KBA double-color COLORA press ( Printing speed 150,000 pairs/hour). At the same time, these devices put higher requirements on the operation and maintenance personnel's technology.
First, common faults and exclusions Breaking a sheet of paper is a very distressing thing, mainly due to the following reasons:
(1) Cracks, tight edges, side bumps, or glue on the sides. When the paper roll is tightly glued or glued on the side, the tape is easily broken, affecting normal paper feeding. It has been found that this type of phenomenon can be wetted with water or tightly adhered to the side of the glue, and the malfunction is eliminated.
(2) The roll itself is not round. Operators can use experience to determine if the eccentricity of the core is too large, and change the paper as needed or notify the machine operator to run at a reduced speed to avoid it.
(3) The lifting speed is too fast or the tension is too large. There is a tension limit on the paper. When increasing the tension, try to keep it away from the limit tension. At high speeds, a very small change can also create very large stresses that can cause web breaks.
(4) Looseness of the guide roller core, misalignment of the level and parallelism, wear of the spindle or bearing. For machines that have been used for a certain number of years, sufficient attention should be paid to them. Maintenance personnel and operators should check the working conditions of the paper guide rollers in time.
(5) Too much ink scale is deposited on the paper guide roller. After a long time, the deposition of ink scale increases the radius of each roller, so that the tension also increases. When the tension reaches the limit, the machine breaks the paper protectively. Therefore, the ink dirt deposited on the paper guide roller should be promptly removed.
2. Sheung Shui, Inking and Imprinting Failures (1) Water Supply The water supply unit can be generally divided into indirect and direct water supply. Whichever method of water supply is used, the purpose is to fully moisten the printing plate and maintain the ink-water balance. The specific manifestations of various faults are: the amount of water on the part of the General Assembly will make the ink dull, gray and dull, ink is not full, in severe cases will produce ink emulsification; water is small, will make the printing plate can not be fully wet, resulting in graphic distortion, Obscure and other phenomena. The specific exclusion method can be adjusted according to the structure of the water supply mechanism and the function of each component.
If you can check whether the pressure between the water baffle motor or the nozzle solenoid valve, the water transfer roller, the water roller, the plate roller and the plate roller is normal to eliminate the fault, you should pay attention to the pressure between the two ends of the water roller. To adjust 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 consists of ink fountain roller, ink transfer roller, ink fountain roller and printing roller. The common faults are: insufficient ink supply, large ink supply, and unstable ink supply. The above failure can be eliminated by checking the operation of the ink fountain roller and the ink nail and whether the pressure between the ink rollers is normal. When adjusting the ink roller, it is necessary to adjust and test whether each roller is balanced, and it is necessary to ensure that the pressure of the ink roller is moderate. The even ink roller and the ink roller cooperate well with each other to keep the printing plate uniform and maximize the ink absorption. Avoid the inconsistency between the depth of the ink before and after printing, and carefully check whether the surface of the plate is smooth and smooth. Whether there is any big flaws, such as indentation, scratches, or poor adjustment of the ink, can cause partial conjunctiva and crystallization. . Due to the large temperature difference between summer and winter, the adjustment may be appropriate to increase the pressure in winter, summer can be properly reduced pressure.
(3) embossing nip part is the core portion of the printing unit, is the most accurate part of the design and manufacture, does not allow a user to adjust the pressure manufacturers generally like parts. Printing pressure is an important factor in ink transfer transfer during the printing process. Appropriate printing pressure is a reliable guarantee that the printing layout, text, and pattern of the printing are clear and clean, the text is not deformed, and the ink is uniformly uniform. Symptoms are mainly ink bleak, unclear dots, and text distortion. The reason is that the ink transfer is not sufficient. It is caused by the loss of elasticity of the blanket or too small lining, just replace the new blanket or increase the thickness of the lining. Can be excluded.
3. There are many factors that affect the registration of color printing in the overprinting part. Various links involved in various printing processes, such as paper, plate making, fountain solution, printing process, and equipment condition, may affect the registration. Here mainly from a mechanical point of view, analyze some common registration faults.
(1) Factors affecting the stability of paper tension Factors that affect the stability of paper tension include the following: paper frame, three-roll (infeed), speed change roller (PIV) and other tension adjustment mechanisms, and other paper guide rollers and draw rollers. Tension adjustment mechanism tension adjustment is not appropriate, or all types of roller parallel, horizontal deviation, or paper frame brake pads wear, roller bearing wear and other reasons will lead to tension instability, resulting in overprinting is not allowed.
(2) Factors Affecting the Accurate Transfer of Graphic Text The printing unit is the direct printing part of the precise transfer of graphic and text. Any mechanical deviation will affect the registration of the printed product. The failure is mainly caused by the wear of the roller bearing, the severe wear of the copper sleeve or bearing of the clutch linkage mechanism, the loose or improper installation of the pin, the wear of the register adjustment mechanism, the wear of the transmission components, and the malfunction of the potentiometer. Although these failures are not common, they should also be carefully checked for mechanical misalignment after the basic elimination of tension factors.
4. The most common failures in the analysis and troubleshooting of the folding section are reported, and there are many causes. We analyzed the reasons for the blocking of Roland and Gaussian folding machines. The main points are as follows:
(1) Rubber strips on folding cylinders are used for too long or aging, resulting in loss of elasticity of the rubber strips or too wide or too deep seams. This causes newspapers to be cut continuously. Several newspapers are linked together and are easily jammed at the flower wheel. . The problem can be solved by replacing the new rubber band.
(2) The cutting knife on the cutting drum is worn or the height of the cutting knife is not in place during the installation, resulting in a jamming due to the continuous cutting of the knife during high-speed operation. The processing method is generally raised by raising the knife holder, that is, adding a knife pad under the knife holder.
(3) Severe wear of the needle, knife, or knife, or the corresponding cam roller bearing is stuck, or the corresponding torsion spring is broken, it will lead to the page not being in place and causing the jam. By carefully inspecting these parts, the problem can be solved by adjusting or replacing the corresponding parts as appropriate.
(4) The cutting knife just cuts off the adhesive tape used for the automatic paper feed and does not cut it, resulting in clogging. This phenomenon is generally rare and there is no suitable solution.
(5) The paper itself is too wet or the water is too large, which makes it difficult to cut and cause blocking during cutting. If the paper itself is too wet, replace the paper roll; if the water is too large, turn off the water in a timely manner.
(6) Improper adjustment of the diameter of the folding roller or inappropriate adjustment of the tension before entering the folding section may result in clogging if the paper or pinhole is pulled continuously. The treatment method is to check if the adjustment of the diameter of the folding cylinder is appropriate and adjust according to circumstances: checking if the tension adjustment of the speed change roller is proper, and whether the pressure roller on the speed change roller is too tight or too loose.
Second, the purpose of maintenance and maintenance <br> maintenance lies in the timely processing of normal or foreseeable use of operating equipment found in some common failures due to technical conditions change and cause, Yasumasa equipment, so not only can improve printing the production efficiency of the equipment, a newspaper earlier time, but also conducive to plant - home to reduce maintenance costs, extend the normal life of the equipment. Here mainly on the analysis of mechanical failure caused by its operating environment, and put forward some reasonable suggestions and maintenance measures.
1. Mechanical failure factors and their maintenance (1) The factors of mechanical failure The printing machinery produces the most failures. In general, the failure of mechanical components is caused by factors such as material selection, processing, assembly, wear, operation, and management. Even if the new offset press, due to some defects in the design of the assembly and installation debugging, in the work of failure. An offset press consists of tens of thousands of parts. Whether the selection of mechanical parts is appropriate, whether the manufacturing and machining accuracy meets the requirements, and whether on-site assembly and adjustment are in place are all important factors causing mechanical failure.
After the machine is used for a certain number of years, due to the gradual wear and tear of the parts, the accuracy will be reduced and various failures will occur. The speed of wear parts, mechanical parts used in addition to material and manufacturing technology related, but also has a very close relationship in time and maintenance measures are appropriate. If the universal shaft and the fork joint with uneven force, wear will cause the instantaneous speed of the transmission to produce periodic changes, resulting in overprinting is not allowed.
Offset press installation and commissioning work is also very important. Many factories ignore the ground strength and hardness issues when setting up the foundation before installing the machine. At present, the medium and high-speed offset presses require extremely high levels of machine bases: the vertical allowable horizontal error cannot exceed 0.08/1000, and the horizontal horizontal error cannot exceed 0.04/1000. After the machine loses its level, the roller journals and sleeves wear out quickly, which can cause printing failures such as ghosts, bars, and paper wrinkles.
Improper operation and management confusion will speed up the formation and occurrence of mechanical failures, sometimes even causing serious consequences. If the surface of the plate cylinder is damaged by a hard object, it will accelerate the damage of the plate and affect the transmission of the picture and text; after adjusting the rubber roller in the machine, all the tools are not taken out in time or a tool is not noticed when it falls into the machine. , may have serious consequences for the operation of the equipment.
(2) Maintenance, maintenance, and maintenance of mechanical components: Cleaning, lubrication, fastening, adjustment, inspection, etc. Three levels of maintenance are generally implemented, namely routine maintenance, primary maintenance and secondary maintenance. Maintenance personnel and operators must take seriously and strictly implement the corresponding maintenance system. The measures we take mainly include the following:
1 Establish daily, weekly, monthly, quarterly, annual maintenance and inspection systems, separate operations, clear responsibilities, and implementation.
2 Conduct systematic operation training for operators and maintenance personnel and operate the equipment strictly in accordance with the operating procedures.
3 Implement the daily equipment inspection system, find abnormalities and conduct timely consultations, and propose further inspections, maintenance and repair measures.
4 Clean up the ink and paper dust on the rollers, paper rollers, folding machines, three rollers, rubber rollers and other parts in time.
5 Regularly refuel each unit where manual refueling is required.
6 Clean or replace the filter element in time, check the oil level of the fuel tank, ensure that there is enough lubricant for the lubrication of gears and other movements, and decide whether to change the oil or not depending on the situation.
7 Check and adjust the brakes of the paper holder regularly. If it is found to be seriously worn, replace it in time.
8 Regularly check and test the working status and performance of auxiliary facilities and perform necessary maintenance to ensure the normal operation of the printing press.