Application of V80 Series PLC in Printing Machine Control System

1 Introduction The printing press is a high-precision machine. The quality of the printed matter depends on the machining and installation accuracy, on the other hand, it depends on the balance of the waterway, the ink path, and the accuracy of the pressure. In order to stabilize the performance of the printed products, the control scheme using the V80 series PLC as the main controller was adopted.

2 System Structure V80 Series PLC Haiweishen Technology Co., Ltd. developed a general-purpose small cost-effective programmable controller, using 32-bit high-performance CPU chip and high-speed logic analysis ASIC chip, program scanning speed, each basic instructions It only takes 0.2μs, and the number of I/O control points is up to 256 points. The user's storage space is large and the performance is stable and reliable.
Due to the input of the two-color printing press, and the output point is more, dual-machine communication is adopted. The upper computer adopts the V80 series M40DR+E16D+E4DA2, which is mainly responsible for the control of the main drive, the control of the clutch pressure of each unit, and the control of the air pump and the air valve. The lower machine adopts the V80 series M40DR+E8AD2, which is mainly responsible for the control of the water roller motor, the speed regulation output of the main drive, and the data acquisition of the versioned motor. At the same time, an eView touch screen was selected, which is mainly responsible for the water roller motor speed display, adjustment display, and fault display of the whole machine.

The system structure is shown in Figure 1:

Among them, the upper computer and lower computer adopt RS485 communication, and the communication protocol adopts Modbus protocol. In the design, each unit must not only consider the safety control, including the emergency stop of the local unit, safety buttons, but also consider the convenience of operation, including each unit should have a punctuality, reverse point button. This results in a lot of input points on the one hand; on the other hand, it is also very inconvenient. Therefore, using dual-machine communication can solve this problem well.
Each color group of the two-color machine has a waterway and ink path device. In order to facilitate the adjustment of the water roller speed, each water roller is controlled by one inverter. At the same time, the speed of the main motor also needs to be adjusted by the inverter. Therefore, in order to achieve multi-path speed adjustment, the V80-E4DA2 analog output module is used. It converts the digital quantity given by the PLC to a 0~10V DC voltage output according to the corresponding algorithm, and achieves a good multi-channel implementation. Speed ​​adjustment requirements.
For multicolor machines, the version adjustment is a more tedious process, and the accuracy of each version of the version will have a great impact on printed products. If overprinting is not allowed, there will be literal overlap or unclear images in the printed matter. In general, the plate axial adjustment range is -2mm ~ +2mm, the circumferential adjustment range is -1mm ~ +1mm. If you use manual adjustment, you will waste a lot of time and the accuracy is not high. In order to achieve automatic pattern making, a potentiometer is installed on the platen roller, and the analog quantity is transmitted to the V80-E8AD2 through a potentiometer. After PLC processing, the rotation accuracy of the plate roller can be well controlled within the pattern-making range.
Through the touch screen, the user is free to combine text, buttons, graphics, numbers, etc. to process or monitor the management of information that may change at any time, can clearly indicate and inform the operator of the current status of the machine and equipment, so that the operation becomes simple and lively. The use of a touch screen also enables standardization and simplification of machine wiring. It also reduces the number of I/O points required for PLC control, reduces production costs, and relatively increases the added value of the entire set of equipment.

3 system design
3.1 Feed Design The overall electrical design of the press is time-critical. There are many proximity switches in the machine to detect different time points. In the printing process, the quality of the paper is an important part of the machine quality. The so-called good or bad paper refers to the phenomenon of no arrogance, double sheeting, etc. If there are arrogant and double-sheet phenomena, under high-speed conditions, the bad paper will be pulled into the machine to destroy the rubber. Give users a lot of losses.
The paper feeding process is shown in Figure 2:

According to the procedure compiled in the above procedure, after the speed is increased to 7000 r/h, the phenomenon of irreversible lock-up will occur, mainly due to the delay of the optical head response time and the delay of the magnet operation time. In order to advance the output of the electromagnet, the input/output refresh instruction of the interrupt programming instruction is used to immediately execute the electromagnet output, and the electromagnet operation time is advanced. Even at a speed of 12000r/h, it is possible to lock the faulty one. Paper.

3.2 Clutch pressure design The accuracy of clutch pressure has a direct impact on the quality of printed products. If the pressure is too early, the embossing cylinder will be soiled, which will cause a lot of inconvenience to the operation. If the pressure is too early, the final paper will not be printed on the complete pattern, resulting in waste of paper.
During printing, the platen roller and the rubber roller are pressed together, and the rubber roller and the roller are pressed together. Since the printing speed is multi-speed, between 3000~12000r/h, different speeds can be selected according to the needs of users. However, due to the use of pneumatic devices for the combined pressure, each cylinder has an operating time and the angle of rotation of the gears is constant. Therefore, when the machine speed is different, the closing time is also different. To solve this problem, based on the theoretical calculations, find out the machine delay time for different machine speeds. With the comparison instruction, when the machine speed is equal to the theoretical value, the corresponding time is delayed, so that the embossing roller and the rubber roller can be accurately pressed.

4. Conclusion With the control scheme of V80 series PLC, the system is reliable, easy to maintain, easy to operate and intuitive, which greatly improves the grade of offset press and is well received by users.