From the repair of offset press roller to offset printing technology and management
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In the domestic printing industry, in the printing process, there are often parts or things falling into the machine drum during the printing process, and the drum body is crushed, and the rubber cylinder and the impression cylinder of the drum body are crushed. Moreover, it is a small-scale roller body crushing or depression. The common method is that the repairman adds the agricultural machine glue to the fine iron powder and then coats it in the low-cracking injury of the roller damage, and flattens the arc surface.
The two imported multi-color offset presses were only printed for six or seven years. The rust-corrosive printing cylinder body made the CD102V Heidelberg four-color offset press in Germany impossible to produce and had to stop for repairs. CD102V Germany Heidelberg four-color offset printing machine four printing cylinders and imported eight printing plate rollers of the American Harris eight-color offset printing machine, there is a large area of rust corrosion, the surface of the drum body from the bite to the tip, the body and Severe rust and corrosion were observed at both ends of the outer and outer sides. After the rust powder was removed, the drum body was measured by the cylinder diameter gauge and the plug gauge. The shallow depression of the depression was 0.35 mm, and the deep depression was 0. .65mm. The US Harris eight-color offset rotary press also seriously affects the quality of product printing. Using high-tech new technology, we made our own testing instruments and repair tools. After more than a month of fighting day and night, we used the manual method of electrolytically brushing all the twelve plate cylinders to reduce the metal copper, chromium and nickel by electrolysis. Brushing evenly over the entire plate cylinder body over and over again, all the unevenly distributed large area and low depression parts are padded up, the pad height is flat, and the surface brushing is quite flat, and the test error is less than 0.04mm. It is a miracle in the domestic printing industry to use a manual electrostatic brush to cover such a small error range. After the start-up printing acceptance, the prints of the full version and the Yinping net are almost the same as the new machine samples. After testing the technical parameters and errors, the quality of the printed products also meets the quality requirements. If the drum is mechanically sprayed or replaced with a new plate cylinder, the roller is installed back to the original position, and the accuracy of the original machine is absolutely not achieved, and the repair cost is at least several hundred thousand yuan, or even one million yuan. Now analyze the causes of this accident, and the corresponding measures in the technical and management of the offset printing process, only for the reference of the printing industry colleagues.
First, the surface of the plate cylinder should be coated with chromium and nickel.
Four-color Heidelberg offset press and eight-color rubber wheel, if the surface of the plate cylinder is zinc or iron, then the metal zinc or iron will chemically react with the acid in the water bucket solution (rust, oxidation), the drum body can not be tight Stickers and plates, such as the roller surface for a long time in the acid, will certainly cause corrosion and rust, if the plate cylinder is changed to chrome or nickel, it will not cause the above accident.
Second, the water bucket solution should not penetrate the surface of the plate cylinder
The operating staff on the machine, if not in accordance with the requirements of the plate-making process technical specifications, the plate liner (0.3mm thick polyester tablet, commonly known as the gun bottom glue) is not flat or damaged and not replaced in time. The plate is not flat on the plate cylinder, especially the damaged pad does not match the two ends of the upper plate and the lower plate cylinder, and the acidic water fountain solution is infiltrated into the surface of the plate cylinder body. . The contact of the acidic water bucket solution with the surface of the plate cylinder will inevitably cause corrosion and rust on the surface of the plate cylinder. The plate must be placed close to the pad, the pad should be close to the surface of the roller body, and there should be no gap between them, so that the acid water solution can be completely prevented from penetrating the surface of the plate cylinder body, and the plate cylinder is not Will corrode rust.
Third, the pH value of the water bucket solution is not well controlled, the acidity is too strong
In the offset printing process, the machine personnel should strictly control the concentration of the water bucket solution. In the operation process, the pH value should be controlled at 5 to 6 under the premise that the pattern is clear, the layout blank is not greasy, and the layout is not dirty or paste. It is better between .5 and printing in strong acid. It also produces low printing durability and high emulsification value of ink. The printed ink is not easy to dry, causing the back to be dirty, the ink to be dim, and the light to be bright and not bright.
Fourth, the layout is too moist
During the offset printing process, the machine operator failed to strictly control the surface moisture of the printing plate, because the moisture control is slightly larger, the printing plate is not easy to be dirty, and the moisture control is less. Once affected by the climate or the external environment, the printing plate is easy to hang dirty. The product will be scrapped. Therefore, we should overcome the idea of controlling the moisture of the layout, "Ningda is not small."
It is very important for the operator of the offset printing machine to master the balance of ink and ink. To measure the level of an offset printing technician, it is necessary to see whether the Sanping work (roller flat, water roller flat, ink roller flat) is done well or not, and whether the ink balance work is well mastered or not. .
Fourth, strengthening process technology management
In the modern enterprise system, enterprise leaders should pay attention to the technical training work for employees, and include this work in the annual plan. They should conduct technical theoretical training for employees in phases and in batches, and strictly control the process technology with standardization, data, and standardization. Mainly in the process management, there is no control over the pH of the plate and the pH concentration of the water bucket solution. The management is not in place. What the offset machine personnel want to do is how it is caused by human accidents. Strengthening the internal process technology management, improving the technical quality of employees, and paying attention to the quality of work can ensure product quality. Through the occurrence of this machine accident, we must take it for granted, and we will not create similar accidents in the future.