A flexographic press is a machine that uses a flexographic plate to transfer ink through an anilox roller to complete the printing process. At present, the flexographic printing machine has become the main force in the packaging and printing industry and is widely used in the environmental printing and packaging industry, such as the printing and processing of labels, packaging paper, paper bags, paper boxes, paper cups and other industries in the food, medical, books, and cosmetics industries. The equipment has a wide range of applications and can be used for printing on various materials such as coated paper, cardboard, copy paper, aluminum foil, self-adhesive, non-woven fabric, BOPP, and PET plastic film. The whole machine is equipped with printing, die-cutting, creasing, punching, folding, waste removal, flat sheet, slitting, hot stamping, laminating, self-adhesive peeling printing and laminating units, and it adopts servo single-axis transmission control. Technology and closed-loop tension control, stable printing tension, accurate positioning, convenient operation, fully meet the needs of various printing occasions. Among them, the pressure control between the anilox roller and the plate roller is the core key equipment of the entire production line. Its pressure control accuracy directly affects the amount of inkjet, which determines the quality of the printed product. Early flexographic printing presses were controlled by mechanical transmission, with low printing accuracy, large mechanical transmission noise and short service life. At the end of the 1990s, the independent motor transmission control mode was adopted, and the printing accuracy and speed were greatly improved. There are many ways to form a supporting control system. This article introduces the Profibus bus system solution based on the Kinco servo in the press control of the web flexo printing machine.

2. Process introduction

As shown in the figure above, the anilox and plate rollers of each group of printing units are respectively controlled by the left and right servos. When receiving the start signal of the central control system of the whole machine, the anilox roller will descend quickly, and the plate roller will move inward to the combined pressure position. ,According to the different printing products, precise fine-tuning to achieve precise pressure control!

The system flow diagram of a single printing unit is as follows

三、system structure

4. System requirements:

    ◆ The positioning accuracy must be ensured between the single set of printing units, and the positioning accuracy is 0.5mm;

    ◆ The main HMI monitors the servo running status of a single group of printing units through the Profibus bus, and displays the running status of each servo motor in real time; the process parameters of a single group can also be set through a single group of HMI!

    ◆ In automatic mode, each group of printing units must start at the same time and arrive at their position at the same time! The time error does not exceed 500 milliseconds!

    ◆ In the automatic mode, if any motor has a fault alarm, the group will stop working immediately (even all other printing units will stop immediately as needed)! The time error does not exceed 100 milliseconds!

    ◆ All process operations can be operated on the main console, or a single group of manual fine-tuning, which is convenient for maintenance, inspection and maintenance!

Five, realization method:

    ◆ Siemens S7-300 PLC simplifies programming through Profibus bus control function, and solves the shortcomings of adopting pulse direction control mode, numerous wiring, inaccurate positioning accuracy due to pulse loss, and poor anti-interference ability;

    ◆ The system is equipped with Profibus bus with the fastest speed of 12Mbps to ensure the control accuracy. Taking the flexo printing machine with at least eight sets of printing units 32-axis system as an example, the main control unit signal can be transmitted to all 32 axes within 100 milliseconds, which is excellent The synchronous start of the system is guaranteed, so the system error is small and the printing accuracy is high.

Six, system configuration:

                                                系统配置表

Seven, program features

    ◆ Kinco's newly listed high magnetic density motor with independent intellectual property rights, with absolute power overload of 300%, real IP65 protection level, extremely low torque ripple, excellent dynamic response, and exquisite appearance design are favored by customers;

    ◆ The system printing error is smaller, the printing speed is faster, and the work efficiency is high;

    ◆ Fast communication speed: Profibus bus has the fastest speed of 12Mbps, which greatly shortens the communication time, improves the system speed, and overcomes the disadvantages of the traditional 485 communication method that the communication speed is slow, the amount of exchanged data is small, and the system communication is easily blocked;

    ◆ Less programming and maintenance workload: In the past, each printing unit has a separate PLC to control the servo, and it is necessary to ensure that the two servos are completely synchronized, so the PLC of this unit needs to be independently programmed. Therefore, the workload of the system is large and cumbersome. At the same time, the number of failure points increases, which leads to an increase in the workload of system maintenance. In this system, all control programming is completed on the main CPU and the programming adopts modular programming. It is very simple to read and maintain. Equipment failure only needs to replace the corresponding failed equipment, no need to download the program again. Different process requirements only need to input different process parameters without additional programming.

    ◆ Convenient operation: The servo drives of all units are directly connected to the Profibus bus. The main CPU further strengthens the parameter setting, running status monitoring and management capabilities of each group of printing units, which simplifies the operation and the maintenance is extremely simple;

    ◆ Powerful fault detection and processing capabilities: The main CPU monitors the servo running status in real time through the Profibus bus, and timely transmits the status information and fault information to the HMI for display. At the same time, the main CPU can respond to the bus according to the failure of each servo drive. Other slave stations take corresponding treatment.

8. Summary

    Kinco Servo's Profibus bus solution for pressure control in flexographic printing presses has been successfully applied in several large domestic flexo printing machine manufacturers. It is the perfect fit for Kinco ED series high performance servo drives and Kinco SMH series high magnetic density motors. Combined application!