The printing equipment of corrugated cardboard printing machine integrates the functions of printing, slitting and indentation production. The structure of the equipment is simple, the area is small, the operation method is simple, and the quality is easy to control. However, if the equipment is aging or the machine is not properly adjusted, some quality failures are prone to occur during printing. The classification analysis is as follows:
1. Dirty version, pasted version or unclear image and text imprint quality problems
1. Quality failures caused by bad parts related to machine imprinting:
When the plate cylinder shaft head, platen roller shaft head, transmission shaft, gear, and key components associated with the platen are worn or loose, the plate cylinder or platen roller will jump or slip during the platen process Phenomenon, and the contact between the printing plate surface and the cardboard is abnormal (that is, the pressure is unstable), which causes the paste printing on the cardboard printing surface or the unclear image and text. In this regard, through careful observation and analysis, to identify the exact location of the fault, take corresponding measures to deal with, repair the worn and loose parts, in order to eliminate the fault phenomenon.
2. Quality failure caused by poor inking roller:
When the head of the inking roller is loose, the inking roller body is bent, deformed or the surface is damaged, it can also cause dirty plates, paste plates or unclear local imprints. After finding out the reason, take corresponding measures to deal with it, so as to maintain uniform and proper contact conditions between the inking roller and the printing plate, and replace the damaged inking roller to eliminate the failure phenomenon.
3. Quality failure caused by improper adjustment of pressure roller:
If the position of the pressure roller is too high or too low, so that the contact with the corrugated cardboard is too tight or too loose, there will also be dirty, pasted or unclear graphics. At this time, the appropriate position of the pressure roller should be adjusted so that the gap between the pressure roller and the cylinder is adapted to the thickness of the cardboard to ensure that the ink color of the printing plate remains clear.
4. Quality failure caused by unsuitable position of paper feed roller:
If the position of the paper feed roller is not adjusted properly, the printed cardboard will not be dried during the conveying process. After the roller is rubbed by the roller, it will cause the transfer of the blot and make the blank layout on the cardboard dirty. To this end, as long as the paper feed roller is adjusted to the part of the cardboard that does not have a printing surface, this failure phenomenon can be avoided.
5. Quality failure caused by improper color order:
If the graphics and text with a full layout are printed in the first color group, when the corrugated cardboard enters the printing process of the second color group mechanism, the printing speed of the first color on the cardboard is slow due to the large amount of ink, so It is very easy to transfer the imprint and cause the layout to become dirty. As long as the layout with a small area is arranged in the first color group for printing, and the layout with a large area is arranged in the rear color group for printing, the failure can be better avoided.
6. Quality failure caused by uneven plate thickness:
When the thickness of the rubber plate is not uniform, there will be a difference in level of the printing plate, where the high plate is easy to paste, and the low plate is prone to incomplete ink, resulting in unclear imprints. In order to avoid the occurrence of this bad situation, for those adopting sporadic plate-making, like the one-time printing layout, made into several small pieces (referring to the plate-making process that saves rubber plates without plate-making core), the same plate should be used Make them separately so that the thickness difference is relatively small. If you have already made a rubber plate, if there is a thickness difference, you can stick an extra layer of tape on the back of the thin local printing plate to keep the entire printing plate at a substantially uniform thickness to ensure the printing pressure and the thickness of the corrugated cardboard with the ink on the plate The quality is caused by unevenness.
After the molded corrugated cardboard, if there are pit marks on the surface that are artificially damaged, the paper surface of the pit area will also have unprinted quality defects. If you use this to increase the printing pressure to make up for it, it will be prone to slurring text and line layout. In order to avoid this situation, during the stacking and handling of corrugated cardboard, you should pay attention to light handling, light handling, and light pressure (to control the stacking height), and avoid using bad production habits such as throwing, smashing, and pressing.
2. Inaccurate or unstable quality of graphic printing position
1. The printing position caused by warpage of corrugated cardboard is not allowed:
If the corrugated cardboard has poor warpage, then the corrugated cardboard is prone to slippage during positioning and paper feeding, and may even prevent the rules on the machine from reaching the edge of the paper, causing the printing position of the cardboard to be inaccurate or incorrect. stable. Therefore, for warped corrugated paperboard, try to use a relatively flat paper edge as the regular paper edge when printing. In addition, we should pay attention to the control of the source of good quality, through the reasonable grasp of the operation process of the single-sided machine, so that the speed of the machine and the preheating temperature, the moisture content of the base paper and the preheating area are relatively in a harmonious state. At the same time, when distributing paper, we should pay attention to the matching of corrugated paper and corrugated paper with similar moisture content, so that the produced corrugated cardboard has relatively good flatness, which can effectively ensure the registration of the printing.
2. Inaccurate printing position caused by improper operation process:
If the position of the plate is improper, it is also easy to cause the position of the layout printing to be inaccurate. Because the corrugated cardboard with warpage defects just enters the plate cylinder, even if there is a slight slip phenomenon, the trailing part of the cardboard will appear obvious deflection. Therefore, the color plate on one side of the corrugated cardboard should be positioned as far as possible towards the starting position of the roller, and the position of the plate is determined according to this, so as to improve the accuracy of the corrugated cardboard.
3. Inaccurate positioning caused by bad machine:
When the machine's chains, rules and other parts are loose, it is also easy to cause the inaccurate printing position of the layout. For this, appropriate measures should be taken to repair and eliminate the looseness of the components to ensure the accuracy of the corrugated cardboard printing position.
3. The indentation line on the cardboard is not clear
The indentation of the printing press is realized when the corresponding portions of the convex wheel and the concave wheel are rolled under pressure, wherein the shaft of the concave wheel can be adjusted to maintain the gap required for the indentation with the convex wheel. If the concave wheel is adjusted too low, it will cause insufficient pressure and make the indentation line unclear. In addition, if the shaft of the convex wheel and the concave wheel is loose, it will also cause the indentation line to be unclear. Therefore, after finding out the reasons, take corresponding measures to adjust and deal with them.
4. The edges of the paper are not cut neatly, and the edges are rough
The slitting of the corrugated cardboard by the printing machine is completed by the upper and lower circular hobs. When the round slitting knife is blunt or the blade is cracked, the contact between the sides of the upper and lower slitting blades is not close enough, the depth of the upper and lower engagement between the slitting blades is insufficient, and the shaft part of the slitting blade is loose, etc. , It is easy to cause uneven cutting of the cardboard, so that the edges of the cardboard appear rough. Therefore, in order to ensure that the edge of the cardboard is cut neatly, the cutting knife must be sharpened immediately when the cutting knife is blunt to keep the blade sharp. For cutting blades that cannot be sharpened and repaired, the blade should be replaced with a new blade; if the machine is loose and the adjustment is uncomfortable, corresponding measures should be taken to deal with it.
The occurrence of the above-mentioned quality failure phenomenon is caused by poor equipment or improper operation. Therefore, it is necessary to carefully maintain the equipment and maintain the printing operation technology to effectively prevent or reduce various qualities. The occurrence of failures has simultaneously improved production efficiency and product quality.
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