Printing ink bar fault imaging judgment and troubleshooting

(1) Failure phenomenon

Our factory has undertaken a batch of packaging jobs, and there are many solid patterns. It is easy to have ink bars when printing . At first we thought that printing more than a few times can improve, but it has no effect. This batch of packaging is an export product, and the middle ink bar cannot eliminate the aesthetic effects.

(2) Troubleshooting process

Careful analysis of the product found that the ink bar appeared in the middle of the pattern. First check the pressure of the rubber roller, coarsely adjust the four plate rollers with a steel sheet, and find that the pressure of the four plate rollers is the same. According to the standard requirements, the first two pressures are larger than the latter two, because the main effect of the first two is ink, and the latter two are ink collection and uniform ink, so the pressure of the last two is smaller than the first two. The roots, and preferably, are reduced in order from the back. Generally, the width of the impression on the plate roller is 5 mm, 5 mm, 4 mm, and 3 mm.

After carefully adjusting the pressure of the plate roller, the test print was printed, and about ten sheets were printed, and the ink stick was still found. Also check the ink roller and the plate cylinder, because if the plate cylinder vibrates too much, the ink bar and ghost image will appear, adjust the string direction of the ink roller, and fasten the thrust bearing of the plate cylinder. There is no big problem with checking the ink roller. Then check each tooth of the gear, and check in detail that there is no problem, and eliminate the gear ink bar caused by the vibration of the gear. I continued to test dozens of sheets and found that the ink stick still exists.

In combination with the previously processed ink bar failure, the method of split conversion is adopted. First, use a casing wrench to loosen the four screws on the gear, then take the gear down and turn it 90° in the circumferential direction. After adjusting, tighten the four screws and test dozens of shots. Check the ink on the drawing. Whether there is any movement of the ink bar with the previous test. If not, check the blanket cylinder and impression cylinder according to the above method, but pay attention to the smaller rotation when changing the position of the stamp. However, we adjusted the two rollers in turn and then tried to print, and the ink on the pattern did not improve.

Carefully observe that the ink bar is just in the middle, and the length of the ink bar is half of the intermediate rubber roller, so continue to check from the rubber roller. The first rubber roller was taken down for trial printing, the ink stick was still present, and the fourth rubber roller was removed for trial printing, and the ink bar remained unchanged. Then take the third rubber roller test, and the one in the ink bar is lightened. Put more ink blotting paper and suck the ink on the machine. As a result, one of the light ink bars is printed twice. Almost can't see it. Immediately after the second ink roller was removed, the test strip found that another ink stick was also relieved, and the position of the fault was basically determined.

In the next test, we installed all the rubber rollers, checked from the rubber roller seat, and in order to prevent a certain part from being missed and to avoid the vibration caused by the vibration of the base, the base of the supporting roller, including the eccentricity. They are all replaced with new ones. After the replacement, the pressure is re-tested and the test is repeated. The fault still exists.

So we put the middle two sets of rubber rollers with dozens of large pressure and small pressure, and observed that the pressure bar with larger pressure is more obvious. On the contrary, the ink bar with less pressure is obviously lighter. At this time, the two or one rubber roller in the middle is taken down, the touch is a bit rough, but there is no big problem, but the rubber roller is oval. Then replaced the spare rubber roller, the fault is solved.

(3) Post-processing

Looking back at the whole process of investigation, at first we found that the pressure of the rubber roller in the middle was not good when we checked the pressure. In the daily work, the two rubber rollers seemed to turn no longer. When the time was long, the high pressure was low and the result was At high pressure, the ink stick is more serious. After that, we turn the elliptical rubber roller under pressure, and the vibration force generated is also increased. The resulting ink stick has not been solved, so only by carefully observing and testing each component can we completely solve it. problem.

The above content is selected from the second edition of 2007, Printing and Printing Technology Digital Printing Arts , and more journal content please pay attention to the journal channel .