Elimination of axial ghosting of the hottest print

2022-08-13
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Elimination of axial ghosting of printed matter

there is a J2108 offset press in operation. The front gauge overprint is very accurate, but the side gauge is inaccurate, resulting in axial ghosting of printed matter, which seriously affects the product quality and has to interrupt production and stop for inspection. The operators rechecked and corrected from the paper output part to the paper feeding part, from the paper positioning mechanism to the paper delivery mechanism, and confirmed that all parts were adjusted in place. The problem of restarting the machine for trial printing has not been solved. After that, they invited experienced teachers to work hard for several weeks and still failed to achieve results. Why can't you find the reason

although the malpractice of irregular overprinting is one of the offset printing faults that have plagued the offset machine operators for a long time, it is not easy to solve, as long as it is not an inherent deficiency in machine manufacturing, it should be said that inaccurate overprinting can be solved. According to conventional logical thinking, the root causes are mostly in the side rules and paper teeth (paper delivery teeth and embossing teeth). Because the vertical overprint is accurate, the positioning of the paper at the front gauge is stable, so there is no doubt. It is always along this road to think and find out the reasons. When you see the slight wear of some machine parts, you can replace them or insert them, and even finally replace the pull gauge at the back end. In a word, all the parts that need to be found or can be found are checked and repaired. It's just right, but it can't solve the problem. In the case of helplessness, it is suggested to check whether there is axial series movement between the paper delivery tooth shaft and each drum. If there is a series movement among them, it will affect the overprint accuracy of the side gauge. So we first checked the nut at the shaft end of the paper delivery tooth on the control surface, and then checked that the locknut at the shaft head end face of each drum body was free of any looseness and slipping. Then use a small crowbar to pry the drum. After careful inspection one by one, it is found that the imprint drum body has axial serial movement. Measured with a dial indicator, the code for design of automatic fire alarm system GB 50116 (9) 8 found that the axial string momentum of the embossing drum reached 1.5mm (according to the requirements of carbon nano development for many years, the axial string momentum of each drum should not be greater than 0.03mm), and the problem was finally found

since the axial string movement of the imprint cylinder is theoretically caused by the loosening of the lock nut on the end face of the cylinder, why is the lock nut on the shaft head at the control end of the imprint cylinder not loose and normal? 2. The number of samples made everyone confused. Remove the lock nut and use special tools to remove it, so as to find the shortcomings of the experimental machine, so as to improve the clutch pressure cam seat on the cylinder shaft head, and check that the cylinder shaft sleeve and thrust bearing are free of any scratch and wear marks, which is ruled out. Install the clutch cam seat again, knock it tightly with a wooden hammer, and then install the lock nut for repeated tests. Finally, it is found that the screw thread on the inner side of the screw plug at the shaft end of the cylinder body has been damaged, resulting in the lock nut being stuck at this position, and the lock is not in place, resulting in the illusion of locking, resulting in the axial series movement of the cylinder body and the axial overprint error during the printing process. Finding the root of the problem is very simple to solve. When repairing, the screw plug can be removed. If a few teeth are damaged, it can be repaired with a assorted file; If a long segment of the back teeth are not working, you can thread it again according to the parameters of the original thread. After repair, install it and start it up for operation. The printing is normal, and the problem is solved

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