Vacuum coating machine process introduction
Vacuum coating machine technology is a new technology developed in China in the early 1980s. Most of it is used to produce IAJ liner and metalized trademark printing paper for cigarette packaging. The production method of vacuum aluminized paper is evaporated in a vacuum chamber. The boat (made of special ceramics) passes a large current of 500 ~ 1000A and is heated to a high temperature of 1200-1500, which causes the aluminum wire to melt and evaporate on it to become aluminum molecules. When the coated paper passes through the vacuum mechanism in the vacuum chamber, Aluminium molecules recrystallized on the glue film of the paper to form a layer of mirror-like aluminum film, so a vacuum aluminized paper was made.
The original problems of the vacuum coating machine control system
The winding mechanism of the coating machine mainly includes a paper discharge roller, a water cooling roller and a paper take-up roller, which are respectively dragged by three DC motors. In order to facilitate the distinction, we label them with the code A, B, and C. Among them, A and B use thyristor DC voltage control to control the speed, A generates paper tension in the power generation state, but the original design is unreasonable, causing the winding mechanism to fail to work at all, mainly because the water-cooled roller and the take-up roller are not coordinated. The paper breaks as soon as the paper is pulled, so the water-cooled roller motor has to be removed to make it a passive roller, and only one delivery roller is used to pull the paper to run, but because each bearing is in a high temperature and high vacuum chamber, the bearing oil is evaporated to dryness. The friction is very large, plus the tension and linear speed of the paper are not constant, and the number of paper breaks is also many. Each time you break the paper, you have to re-evacuate, lead the paper, and joint, which wastes about half an hour or so, which seriously affects production. Therefore, in order to improve the output and quality of the product, the problems of constant tension and constant linear speed of the paper need to be solved.
Design of constant tension and constant linear speed control system for paper in vacuum coating machine
The overall design scheme is: the tension of the paper is generated by the motor A working in the power generation state, and the generator excitation is adjusted by the feedback of the armature current of the generator to make the tension F; it is kept constant, and the motor B is only used to overcome the friction of the water-cooled roller However, in order to make the linear speed of the paper constant, its control system is designed as a double closed-loop stable speed system.The motor C is used to overcome the friction of the take-up roller and the tension of the paper FZ, and its own speed control must also be designed as a double Closed-loop control system, as for the speed coordination problem and tension control problem between the take-up roller and the water-cooled roller Naishu (even if the linear speed of the paper v3 equals v :, the tension of the paper F: equals F;) by the tension speed regulator In addition, in order to make the winding system start smoothly, the speed setting channels of the take-up roller and water-cooled roller are marked as USG :, and USG: is uniformly given by a given integrator.