Selection Guide for electrostatic ink transfer dev

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Selection Guide for electrostatic ink transfer device of gravure press

the electrostatic ink transfer device is composed of electrostatic pressure roller, conductive aluminum roller (or conductive brush), control cabinet (including high-voltage electrostatic generator), etc., as shown in Figure 1

its working principle is shown in Figure 2. It generates high voltage and low current through the control cabinet, and transmits the current to the electrostatic pressure roller through the conductive aluminum roller or conductive brush. In this way, the electrostatic pressure roller carries positive (or negative) charges, so that the electrostatic pressure roller establishes a high voltage electrostatic area between a conductive surface in contact with the paper, the paper and the gravure plate. Under the action of static electricity, the ink in the gravure plate is sucked out and evenly transferred to the paper surface, making the ink transfer rate reach or close to 100%

in the process of electrostatic loading, positive or negative charges should be selected according to the color of the ink, the composition of the ink and the positive and negative electrostatic charges on the surface of the paper

precautions for selecting electrostatic ink transfer device

1. The first is the selection of the manufacturer of electrostatic ink transfer device. If the company has certain strength, it should choose imported products, mainly from manufacturers in Germany and Japan. The price of each electrostatic pressure roller is about 8000 yuan, 15000 yuan, 200000 yuan (excluding electrostatic pressure rollers) is required for each color group to be completed. At least 3-4 groups are required for each gravure production line, which requires hundreds of thousands of yuan of funds, but this is also a long-term investment in gravure vision products. If domestic devices are selected, it is understood that at present, only two companies in Beijing and Tianjin are relatively successful. The price of each color group is about 35000 yuan (including electrostatic pressure rollers). Such a production line only needs 150000 yuan, which is equivalent to the price of a color group of similar foreign products

2. After the manufacturer is selected, it is necessary to determine some parameters and auxiliary facilities of the device, such as electrostatic loading mode, electrostatic pressure roller, width of printing machine, width of printing products, etc

(1) there are two main ways of electrostatic loading, namely, aluminum roller and electrostatic brush. These two methods have their own shortcomings, such as: there is a gap between the aluminum roller and the electrostatic pressure roller when loading; When the brush is loaded, the brush is easy to wear and deform, which will cause uneven electrostatic loading

(2) when selecting the electrostatic pressure roller, it should be distinguished from the pressure roller. The surface of the electrostatic pressure roller must be conductive, and its hardness should be different from that of the pressure roller. Generally, the hardness of the pressure roller should reach hs90, and the hardness of the electrostatic pressure roller should be controlled at hs80-85 according to the different equipment. It is too soft and easy to cause wear, which can make the graph display with the best size and poor usability; Too hard and easy to cause incomplete ink transfer, electrostatic effect is not obvious

(3) the width of the printing machine and the width of the printing product should be considered together to solve the production of electrostatic pressure rollers and the length of conductive parts. In the past, the length of the electrostatic pressure roller was the length of the conductive part, which was easy to cause the paper to break, or the paper edge was damaged, and it could not be used on the machine. Now, the length of the electrostatic pressure roller is divided into conductive part and insulating part, just like using the pressure roller

electrostatic transfer can reduce the weight of the whole vehicle by 35% compared with 2015. Precautions in the use of the ink device

because the electrostatic ink transfer device is mainly used when printing eye-catching products, it is necessary to install the electrostatic pressure roller every time, readjust the pressure, and the preparation time is long. In addition, in order to ensure better ink transfer effect and safety during printing, the following matters must be paid attention to

1. check the installation position of the electrostatic pressure roller. The pressure of the pressure roll and the pressure at both ends of the pressure roll

2. Check the installation position of conductive aluminum roller and electrostatic brush and the wires connected to the electrostatic control cabinet

3. check the working state of the pressure switch or speed controller

4. Zigzag experiments should be carried out on metal materials such as steel plates, ribbed steel, round steel, and just welded parts. The loading of electrostatic voltage should be carried out when the speed of the gravure press reaches more than 30 m/min. according to the improvement of printing effect, gradually increase the voltage from scratch. If increasing the voltage has no obvious effect, stop increasing the voltage, change the polarity of the loading voltage, or check the existing problems in time

5. If the visual printing effect is not improved after using the electrostatic ink transfer device, the surface flatness of the used paper and the engraving quality of the holes on the printing plate should also be checked

shortcomings of electrostatic ink transfer device

due to the relatively narrow scope of use of electrostatic ink transfer device in China, the research on this technology has just started. At present, domestic devices that are widely used still have some shortcomings, and I hope colleagues can take this as a lesson

1. The maximum number of engraving lines of gravure eye tone products can reach 175 lines/inch, which greatly restricts the fineness of gravure holes. Therefore, only the electrostatic ink transfer device is used to improve the level of products. The fine level is still difficult to meet the requirements

2. Adding static electricity to the paper through the electrostatic pressure roller will cause a strong electrostatic area within about 300mm of the paper just leaving the gravure, so the electrostatic elimination device must be installed in this part, otherwise it is easy to cause ink tank fire due to high electrostatic intensity. Although the fire will not cause great losses, it has buried potential safety hazards

3. The current electrostatic ink transfer device still has great shortcomings in gold printing and coated paper printing, and the printing quality has not been significantly improved

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