The elimination of axial ghosting of printed products

In the case of a Taiwan J2108 offset press, the front register printing was very accurate, but the side gauges were not accurate, causing axial ghosting of the printed products, which seriously affected the quality of the products and had to interrupt the production and shutdown inspection. From the paper-out part to the paper-feeding part, the operator re-checks the correction from the paper positioning mechanism to the paper-feeding mechanism, confirms that all parts are in place, and the problem of restarting the test-printing has not been solved. It was still not effective in a few weeks. Why can't I find the reason?
The disadvantages of overprinting are not one of the types of offset faults that have long plagued offset press operators. They are not easy to solve, but as long as they are not congenitally deficient in machine manufacturing, it should be said that overprinting can be solved. According to conventional logical thinking, the root cause is mostly in the aspects of lateral regulation and gripper (handing of paper and embossing). Because the vertical overprint is accurate, the positioning of the paper at the front gauge is stable, but it is not necessary to doubt it. It is always along this road to ponder and find the reasons, see some of the slightest wear and tear of the parts will be exchanged or nested, and even replace the back end of the pull tab. In short, the parts that are to be found or found can be searched and repaired and corrected, which cannot solve the problem. In the case of frustration, it was suggested to check whether the delivery shaft and the rollers are axially tangled. If one of them moves, the overprint accuracy of the side gauge will be affected. Therefore, we first checked the nut on the feed end of the feed end due to the control surface, and inspected the lock nut on the end face of each cylinder body without any looseness or slippage. Then, using a small tamper bar, the squeegee body was found to have axial turbulence. Measured with a dial indicator, it was found that the axial movement of the impression roller reached 1.5 mm (according to the requirement, the axial movement of each roller should not exceed 0.03 mm), and the problem was finally found.
Since the impression roller appears to be axially converging, it is logical that it is caused by the loosening of the locking nut on the end face of the drum. Why does the shaft locking nut of the impression roller have no loosening phenomenon and is normal? This makes everyone feel puzzled. Remove the lock nut and use a special tool to remove the clutch press cam seat on the shaft of the impression cylinder. Check the roller bushing and the thrust bearing without any signs of abrasion. This possibility is ruled out. The clutch cam seat was reinstalled, and the wooden hammer hit it. Then the lock nut was loaded and tested repeatedly. Finally, it was found that the screw teeth on the inner side of the cylinder shaft end of the drum were bad, causing the lock nut to be jammed in this position. , The lock is not in place resulting in the illusion of locking, resulting in the axial string of roller body during the printing process and axial misalignment. Finding the source of the problem and solving the problem is very simple. When repairing, the screw plug can be detached. If the individual tooth is damaged, it can be repaired with the casket; if the back of a long section of tooth is not OK, you can re-set the wire in accordance with the parameters of the original thread, and then fix it. On the boot operation, printing is normal, the problem is solved.

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