Discussion on the transformation of Web concave machine with AC servo technology (Part 2)
5.3 overprint principle
in multi-color printing, the rotation angle of the printing plate cylinder is generally changed to adjust the printing position. The closed-loop control principle is shown in Figure 4
according to the principle of rotary encoder, the more the number of lines, that is, the more the number of pulses generated by the printing plate per revolution, the higher the position accuracy. Assuming the perimeter of the printing plate is 500mm and the number of encoder lines is 500, 500mm corresponds to 500 pulses. However, it is often used. 2. Put a suitable fixture on the copper rod tensile testing machine. When the experimental space is about 2 meters, the user should choose a 3-meter model. 1mm corresponds to 1 pulse and 20mm corresponds to 20 pulses.
the actual printing position is detected by converting the detected color code signal into electrical pulses through the photoelectric scanner, These electric pulses and the pulse train generated by the rotary encoder are sent to the overprint system computer at the same time. The given value of the distance between the color codes of each color group is 20mm, that is, when the two colors are set, the distance between the two color codes is 20mm, corresponding to 20 pulses of the encoder. As shown in Figure 5, 18 pulses are counted in the trigger time period of color code 1 and color code 2. If color code 1 is taken as the benchmark, it indicates that the printing plate shaft speed of color code 2 is too fast. In order to slow down its speed and correct the position deviation, the servo motor should be reversed by an angle equivalent to 2 pulses; Assuming that the number of pulses in the trigger period of the two pulses of color code 2 and color code 3 is 23, taking color code 2 as the benchmark, it indicates that the printing plate shaft speed of color code 3 is too slow. In order to speed up the speed and correct the position deviation, the servo motor should be made to rotate forward the four ball friction and wear tester and the wear spots. The model measurement system with the maximum selection of 5 tons is equivalent to the angle of 3 pulses to eliminate the deviation
source: China Automation