How to choose UV curing device for rotary gravure production line
Based on the correct understanding of the UV curing process technology and the correct selection of UV curing devices, the following principles should also be noted.
(1) Determine the installation location. Generally installed on the top of the oven of the gravure color group, the reasons are as follows: the installation space is large, the paper roll and the cooling roll are easy to install; the exhaust heat is simple; the paper path is longer, which is conducive to the leveling of UV varnish. Of course, when determining the installation position of the UV curing device, it is also necessary to consider the actual situation of different gravure printing machine models. If the space position is sufficient, it can also be installed after the last color group.
(2) Correctly determine the power and number of UV lamps according to the speed and effect required for printing. If the power of the selected UV lamp is too large or the number of groups is too large, it will cause unnecessary waste; if the power is too small or the number of groups is too small, the desired effect cannot be achieved.
(3) The UV curing device should be designed to be movable as much as possible, so that it is convenient to load and unload, and can be flexibly moved when the product or process changes.
(4) The speed of rotogravure printing is relatively fast. When designing a UV curing device, it should be considered to divide its power into several gears according to the speed of gravure printing, so that it can take into account the energy saving and safety of production.
(5) In view of the slower cooling speed of the air-cooling method and the long-term operation of the UV curing device, there are hidden safety hazards. Therefore, it is recommended that the UV lampshade adopt a circulating water cooling method to prevent the hidden safety hazards caused by the high UV curing temperature.
(6) The UV curing device should be as far away as possible from the ink tank and ink tank to avoid the ink drying and skinning after ultraviolet irradiation.
(7) The safety and reliability of the UV curing device must be guaranteed to prevent fires.
Examples of renovation plans
1. Status of equipment
A printing company installed a 6-color rotogravure printing machine for wood grain paper produced by Zhongshan Songde Packaging Machinery Co., Ltd. in February 2009. The basic features of the equipment are as follows:
(1) Mechanical shaft transmission, the maximum mechanical speed is 150m / min;
(2) The width is 1300mm;
(3) The equipment is paper-through;
(4) The 6 color groups all use strengthened double oven.
2. Purpose of transformation
Originally, the 6 color groups of this equipment are all heated by electric heating and hot air drying method, and they can be printed with solvent ink or water-based ink. .
3. Transformation plan
According to the basic characteristics of the equipment and process requirements, considering the structure and cost of the light box, it is determined to install the UV curing device on the top of the oven of the sixth color group of the gravure printing machine, and connect the heat dissipation device to the air duct device of the gravure printing machine. Imported UV lamps are used. The curing width of each lamp is 700mm and the power is 12kW. Each two lamps are connected as a group. Therefore, the effective curing width can reach 1300mm; in order to meet the curing speed of 120m / min, the final adopted Two sets of lamps (a total of 4 lamps); using circulating water cooling. The final configuration of the UV curing device is: 1 electric cabinet, 4 fans, 4 light boxes, imported UV lamp tubes, imported electrical control parts (Schneider). In terms of control methods, we considered the following two methods.
(1) Classification control method
Start the UV curing device to enter the standby state, at this time the UV lamp cover is closed, start the printing press button, the UV lamp enters the working state â… while the UV lamp cover opens, and the UV lamp enters the working state â…¡ when the printing speed increases to a certain setting When the printing speed decreases, the power of the UV lamp decreases accordingly. When it drops to a certain set value, the UV lamp cover closes. The temperature control device is set in the light box. When the wind temperature is higher than the set value, the UV lamp is turned off, the fan is started and the power is delayed. The water cooler is equipped with a flow switch and a thermostat. When the flow is less than the set value or the water temperature exceeds the set value, the UV lamp is automatically turned off. This solution has lower cost and mature technology.
(2) Stepless control method
After adopting the stepless control method with transformer, start the UV curing device to enter the standby state, at this time the UV lamp cover is closed; start the printing press embossing button, and the UV lamp enters the working state when the UV lamp cover is opened. When the printing speed changes, the output power of the UV curing device is changed by adjusting the transformer of the controller to adjust the effective curing power of the UV lamp, that is, when the printing speed increases, the power of the UV curing device increases; when the printing speed decreases, When the UV lamp power drops, when a certain set value is reached, the UV lamp cover is closed, the fan is started and the power off is delayed. There is a temperature control device inside the light box. When the wind temperature is higher than the set value, the UV lamp is turned off. The water cooler is equipped with a flow switch and a thermostat. When the flow is less than the set value or the water temperature exceeds the set value, the UV lamp is automatically turned off. The program has a large investment.
After analysis and research, it was decided to adopt the stepless control method. Although the investment is high, the control technology is advanced and the operation effect is good. It has been verified by practice that after more than half a year of operation, the effect is remarkable and in line with expectations.
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