Parameter control of printing hose of the hottest

2022-08-09
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Parameter control of flexographic printing machine printing hose

the process of printing hose with unit flexographic printing machine is basically the same as that of printing coated paper, offset paper and self-adhesive paper, but because the composite sheet is thick, the total thickness is about 300 m, the quantity is large, and the inner and outer surfaces are PE films, so compared with general paper or self-adhesive, cardboard, etc., the control of printing tension and printing pressure is particularly critical. 1. Control of printing tension

the tension system of the unit flexographic printing machine is divided into three parts: the unwinding part, the printing part and the rewinding part, which can instantly measure and record the program of measuring the opening displacement at the root of the crack The characteristic curve part of the data in the process of impact. For example, the gelas em410 unit flexographic printing machine is equipped with a set of swing roll unwinding tension control system, two sets of printing tension control system and one set of winding tension control system to ensure the stability of tension. The function of the tension control system of the unwinding part (also known as the pre leveling tension system) is mainly to straighten and tighten the composite sheet in advance, so as to improve the phenomenon of uneven tightness, surface wrinkle, unevenness and ruffle edge of the composite sheet in the manufacturing process

the tension control system of the printing part refers to the rubber pressure roller that passes through the second leveling tension system from the sheet to the constant tension value in the printing process after printing. These two groups of tension control devices are collectively referred to as the printing tension control system. Their function is to balance the printing pressure of each plate roller on the composite sheet during the printing process and the tension and resistance between the composite sheet and the paper feeding roller, UV cooling roller and other rollers, and keep the tension constant during the printing process. The printing tension should depend on the bending stiffness of the composite sheet. The higher the bending stiffness of the composite sheet, the greater the tension value should be; On the contrary, the tension of the composite sheet should be smaller

in actual production, because the surface friction coefficient of the composite sheet is relatively small, and there is aluminum foil as the skeleton in the middle, we should set the tension as much as possible, but also ensure that the composite sheet will not be stretched and deformed after printing. Taking the composite sheet with a width of 400mm and a total thickness of 275 m as an example, the printing tension is usually set to about 320n at the front end and 360n at the rear end. The suitable point of printing tension control is based on the standard that all chromatic points in multicolor printing are registered and do not move back and forth. In addition, it should be noted that the speed of printing will also affect the stability of printing. Our approach is to first set the printing tension within the common range of the sheet specification used, then basically register the printing plates of various color groups, gradually increase the speed to the normal production speed, and then fine tune the printing tension according to the moving trend of the chromatic point

the tension system of the winding part refers to the constant winding force and torsion of the back-end winding of the flexographic press during the roll to roll production. Its function is to roll the printed materials neatly and keep the rolling force of the whole roll of sheet from the inside of the roll core to the outside of the roll core consistent. When printing composite sheets, in order to make both sides of the toothpaste sheets that have been cut into small rolls smoother and the rolling force and torsion of each roll more stable, we set relatively fixed rolling force and torsion values according to the data obtained in actual operation. The set value is: coil force 60%, torque 50%, which ensures the stability of the quality of each coil of sheet during pipe making and processing

the accuracy of tension control determines the overprint quality of printing and the overall quality of finished products when printing hose sheets with unit type flexographic printing machine. There are many factors that determine the tension value, including the change of the production environment of each batch of composite sheets, the different sheet manufacturers, the different equipment for manufacturing sheets, the different width of composite sheets during printing, the different printing equipment, etc

2. Control of printing pressure

the adjustment of printing pressure is another key factor to ensure product quality. Before each printing, the pressure between the embossing roller, plate roller and embossing roller must be readjusted. The adjustment of printing pressure mainly includes two aspects: one is the pressure between the wrinkle roller and the plate roller; The second is the pressure between the plate roller and the impression roller

first, adjust the spacing between the three rollers. During printing (the unit is in the pressed state), the spacing between the wrinkle roller and the plate roller and the spacing between the plate roller and the impression roller are basically the same. Namely: 0.38mm250 ℃ ± 0.10 (double-sided tape thickness) + 1.70mm (plate thickness) =2.08mm. When the old-fashioned unit is pressed, place the kraft paperboard at both ends of the roll gap, and manually adjust the spacing between the embossing roll and the plate roll, and between the plate roll and the embossing roll, taking the same resistance of pulling the kraft paperboard at both ends as the standard. At this time, the spacing is the ideal pressure value in printing, but it is slightly different from the printing pressure used in actual production, which requires operators to make fine adjustments in normal production

before production, pressure positioning shall be carried out for each color deck first, and the pressure between the plate roller and the impression roller shall be relaxed (pay attention to the synchronization of the operation surface and the transmission surface). When the flexographic printing machine is running at a slow speed, start pressing from the printing unit of the first color group, first observe whether the ink transfer of the inking roller to the embossing roller is uniform, and then observe whether the ink transfer of the embossing roller to the plate roller is good, and then gradually increase the pressure between the plate roller and the embossing roller until pictures and texts are printed on the composite sheet (pay attention to maintain the synchronization of the operating surface and the driving surface, and ensure that the pressure is increased at both ends at the same time and evenly). Check whether the printing points on the sheet are clear. With the improvement of refinement and processing depth, the transformation and upgrading of chemical industry, whether the pattern and text are complete, and whether there are problems such as whiteness and emptiness on the ground. In view of these problems, slightly adjust the pressure between the plate roller and the embossing roller

flexographic printing is a light pressure printing process, and its printing pressure is far less than that of offset printing and gravure printing. When setting the flexographic printing pressure at ordinary times, it is mainly required to be small. However, in the case of hose printing, the printing pressure should be deliberately increased slightly because the substrate is a composite sheet. Take the field version as an example, adjust the printing pressure to vaguely see that there is a pressure frame at the edge of the field, so as to avoid the leakage of printed graphics and texts caused by the uneven thickness of the composite sheet per unit area

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