The roller of the printing press is installed on the roller. Each roller has two rollers, which are used to drive the rotation of the roller and control the elasticity of the teeth on the roller. Tooth roller has a great effect on ensuring the smooth progress of the printing process. It is worth noting that if there is a problem with the roller, it may cause ghosting failure, but few operators will The fault is associated with the tooth roller. The author has a deep understanding of this, and here is a summary of some of his experiences. He hopes to discuss it with people in the industry.
Ghost failure caused by no rotation of both tooth rollers
In the process of printing, the paper must undergo multiple handovers, and the role of tooth decay is very important. If there is a problem with cavities, problems such as wrinkling, ghosting, misregistration, and color cast may occur. The problem of tooth decay is generally caused by factors such as wear of the dental pad and the dental chip, unevenness, and fatigue failure of the dental spring. However, if there is a continuous ghosting of the printed product and there is a color cast at the same time, it is necessary to consider whether or not the roll has a failure. Most multi-color printing presses nowadays use double-diameter impression cylinders and transfer cylinders. The above conditions are mostly caused by the inconsistency in the force of the two teeth on the same drum and the non-rotation of the two molar rolls. Different due to. If the two rollers do not rotate, the degree of wear will inevitably vary, and it will not be possible to maintain a uniform grip on the caries, and the process of handling the paper will be difficult to maintain in a stable manner. When the rollers are handed over, the paper has been warped and even wrinkled, so that when the latter colors are printed, when these deformations (or wrinkles) are partially rolled off, the first color print (especially the tail) is The axial direction is larger than the latter color. As a result, the printed dot of the first color part is severely deformed, the handwriting is not clear, the lines appear double lines, and the color area appears color cast.
The solution is to find the roller that cannot be turned according to the ghosting and color cast of the printed product. Take measures such as loosening and oiling to make the roller re-rotate, and then try to print a few sheets. If the ghost disappears, then If the problem is solved, if the problem persists, the roller has been completely worn and needs to be replaced.
Two tooth rollers have a ghosting failure caused by no rotation
There is a non-rotation of the two crooked rollers, which often causes some bizarre problems. The problem I encountered was that the printed product “beats up and downâ€, that is, good prints and bad prints appear alternately and regularly. indefinite. This situation can make many operators overwhelmed: blankets are rubbed over and over, plates are disassembled several times, and the equipment is continuously calibrated, but it is still difficult to find the cause of the problem.
This situation generally occurs on four-color printing presses. Four-color printing presses have four units, and the probability of such problems is relatively large. As a rule of thumb, if one of the two roller rolls does not rotate, it will not only cause ghosting failure, but it will also affect the color reproduction of the four-color printing press, resulting in color cast. Among them, ghosts appear in the form of alternately appearing prints with ghosts and prints without ghosts; the expressions of color casts alternate with prints and color prints whose colors meet the requirements of the original. The root cause of this problem is that the non-rotating creasing roller causes insufficient force on the caries to cause ghosts to appear on the prints; when the rollers turn to the normal carious roll, Prints are normal. In the same way, the reason for the repeated color cast is that due to the previous colors, the color run phenomenon will appear when the problem occurs in the unit of the roller.
This type of problem occurs and the non-rotating crucible roller should be oiled and loosened. If the roller can be loosened, correct the two tooth axes to ensure that the force of the teeth is even; if it is not loose, it should be removed and replaced.
There are many causes of ghosting failures, and the rotation of the roller is only one possibility. Moreover, the probability that the crooked roller does not rotate will be low unless the operator does not pay attention to the daily maintenance of the printing machine, such as not washing the car in time after the print job is finished, not oiling the printing machine, etc. In addition, if there is paper waste and rubbish on the roller This can also happen if the normal rotation of the roller is blocked. Therefore, attention should be paid to the maintenance of the roller.
Ghost failure caused by a roller
January 22 11:06:30, 2020
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