How to deal with the quality failure of corrugated

How to deal with the quality failure of corrugated board printing machine

corrugated board ink "> the printing equipment of the printing machine integrates the functions of printing, slitting and indentation production. The equipment has simple structure, small floor area, simple operation method and easy quality control, and plays a certain role in the production process of ink"> cartons. However, if the equipment is aging or the machine is used and adjusted improperly, it is easy to have some quality faults during printing. Now it is classified and analyzed as follows:

I. The quality faults caused by dirty version, paste version or unclear local image and text imprinting of the layout graphics and text

1. The quality faults caused by the poor related parts of the machine imprinting:

when the shaft head of the plate cylinder, the shaft head of the imprinting roller, the transmission shaft, the gear and the key parts related to the imprinting appear wear In case of looseness, the plate cylinder or the imprinting roller will jump or slide during the imprinting process. Under the condition of small deformation, the contact between the printing plate and the paperboard is abnormal (i.e. the pressure is unstable), resulting in the pasting of the paperboard printing plate or the unclear imprinting of local pictures and texts. In this regard, we should carefully observe and analyze the impact of the manufacturing process on the working intensity characteristics, find out the exact location of the fault, take corresponding measures to deal with it, and repair the worn and loose parts, so as to eliminate the fault phenomenon

2. Quality failure caused by poor inking roller:

when the inking roller shaft head is loose, the inking roller body is bent, deformed or the surface is damaged, it will also cause dirty plates, pasted plates or unclear local graphic imprints. After finding out the cause, take corresponding measures to deal with it, so that the inking roller and the printing plate can maintain uniform and appropriate contact conditions, and replace the damaged inking roller in order to eliminate the fault phenomenon

3. Quality failure caused by improper adjustment of pressure roller:

if the position of pressure roller is too high or too low, so that the contact with corrugated board is too tight or too loose, there will also be dirty version, paste version or unclear local image and text imprint. At this time, the appropriate position of the pressure roller should be adjusted to make the gap between the pressure roller and the roller adapt to the thickness of the cardboard, so as to ensure that the ink color of the printing plate remains clear

4. Quality failure caused by improper position of the paper feeding roller:

if the position of the paper feeding roller is not adjusted properly, the imprint on the printed paperboard will be transferred and the blank layout on the paperboard will be dirty after being rubbed by the roller because the imprint on the paperboard has not been dried. In this regard, as long as the paper feeding roller is adjusted to the position where there is no printing page on the cardboard, the occurrence of this fault phenomenon can be avoided

5. Quality failure caused by improper color sequence:

if the pictures and texts with a full page are arranged in the first color group for printing, when the corrugated board enters the second color group mechanism for printing, because the printed pictures and texts of the first color on the board have a large amount of ink and slow drying speed, it is very easy to transfer the imprint and cause the page dirty. As long as the layout with small area is arranged in the first color group for printing, and the layout with large area is arranged in the rear color group for printing, this fault can be avoided better

6. Quality failure caused by uneven thickness of the printing plate:

when the thickness of the rubber plate is uneven, the height difference of the printing plate layout will appear, and the high part of the layout is easy to paste the plate, and the low part of the layout is easy to appear incomplete inking, resulting in unclear impressions. In order to avoid this bad situation, for those that use sporadic plate making, such as a printed plate, and make several small blocks (referring to the plate making process that saves rubber plate material without plate making core), the same plate should be made separately, so that its thickness difference is relatively small. If there is a thickness difference in the prepared rubber plate, you can stick an extra layer of adhesive tape on the back of the thinner local printing plate to keep the thickness of the whole printing plate basically the same, so as to ensure the quality caused by the printing pressure and the uneven thickness of the corrugated board inked on the plate

if there are artificial dents on the surface of the formed corrugated board, the paper surface at the dents will also have unclear imprints and quality defects. If we increase the printing pressure in an all-round way to make up for this, it is easy to cause the defects of text and line layout pasting. In order to avoid this situation, during the stacking and handling of corrugated cardboard, attention should be paid to handling, placing and pressing gently (the stacking height should be controlled), and it is forbidden to use bad production habits such as throwing, smashing and pressing for handling

II. The printing position of the layout is inaccurate or unstable quality fault

1. The printing position is inaccurate caused by the warping of the corrugated board:

if the corrugated board has bad warping, then the corrugated board is prone to slip in the process of positioning and feeding, and even the rules on the machine may not touch the paper edge, The printing position of the paperboard was inaccurate or the booklet was compiled by technical experts organized by Guangxi Institute of metrology. Therefore, for warped corrugated board, the relatively flat paper edge should be used as the regular paper edge for positioning when feeding and printing. In addition, we should pay attention to the control of the quality source, and make the speed of the machine in a relatively coordinated state with the preheating temperature, the moisture content of the base paper and the preheating area through the reasonable control of the operation process of the single-sided machine. At the same time, when distributing paper, we should pay attention to the matching mounting and forming of box board paper and corrugated paper with similar moisture content, so that the flatness of the produced corrugated board is relatively good, which can effectively ensure the registration of printing

2. Inaccurate printing position caused by improper operation process:

if the plate is installed in an improper position, it is also easy to cause inaccurate printing position of the plate. Because when the corrugated board with warping defects just enters the plate cylinder, even if there is a small amount of slip, the trailing tip of the board will also appear obvious deflection. Therefore, the layout with chromaticity on one side of the corrugated board should be positioned towards the starting position of the drum as far as possible, and the loading position should be determined according to this, so as to improve the overprint accuracy of the corrugated board

3. Inaccurate positioning caused by poor machine:

when the chain, rules and other parts of the machine are loose, it is also easy to cause inaccurate printing position of the layout. For this, corresponding measures should be taken to repair, and the accuracy of corrugated board printing position can be guaranteed only after the loosening of parts is eliminated

III. the indentation line on the paperboard is not clear.

the indentation of the printing machine is realized when the corresponding part of the convex wheel and the concave wheel is pressurized and rolled, in which the shaft rod of the concave wheel can be adjusted to maintain the required gap between it and the convex wheel. If the concave wheel is adjusted too low, it will cause insufficient pressure and unclear indentation line. In addition, if the shaft rods of convex and concave wheels are loose, the indentation line will also be unclear. Therefore, we should find out the causes and take corresponding measures to adjust and deal with them

IV. the edge of the paper is not cut neatly, and the edge is rough.

the cutting of the corrugated board by the printing machine is completed by rolling the upper and lower circular hobs. When the circular slitting knife is blunt or the blade cracks, the side contact of the upper and lower slitting knives is not close enough, the depth of the upper and lower intersection between the slitting knives is insufficient, and the shaft rod of the slitting knife is loose, it is easy to cause uneven slitting of the paperboard, resulting in rough edges of the paperboard. Therefore, in order to ensure that the edge of the paperboard is cut neatly, the cutting knife must be sharpened immediately to keep the blade sharp when it is blunt. For the slitting knife whose blade cracks and cannot be grinded and repaired, it should be replaced with a new blade; Corresponding measures shall be taken to deal with mechanical looseness and improper adjustment

the above quality failures are caused by poor equipment and improper operation. Therefore, it is necessary to carefully maintain the equipment and control the printing operation technology at ordinary times, so as to effectively prevent or reduce the occurrence of various quality failures and synchronously improve the production efficiency and product quality