High Speed ​​Gravure Printing Machine Tension Control System Solution

I. Project Overview
With the continuous development of domestic flexible packaging materials, the variety, quality and quantity of its packaging products are increasing. The requirements for the printing speed and the printing precision of printing machinery are also increasing. The gravure printing machine has a wide range of applicable materials (BOPP, PET). , PVC, PE, aluminum foil, web, etc.) and high operating speeds (up to 400m/min) have broad market prospects.
Group gravure printing machine (hereinafter referred to as gravure printing machine) is an important member of the printing press family. He occupies an important position in the field of flexible packaging with exquisite printing quality. The gravure printing machine generally consists of unwinding, unwinding, drawing and printing. In order to ensure a good printing effect, the four components of the film must be controlled precisely and stably. However, the traditional tension control method restricts the development of high-speed gravure printing presses. Speed ​​technology has become increasingly sophisticated, and tension control using AC motors has become
For reality, and for most of the high-speed gravure printing machine used abroad.
In order to reduce costs, improve product quality, and improve product competitiveness, according to the characteristics of printing machinery on the control system's operating speed and stability, we have successfully developed the AP series tension control system in cooperation with Japanese technicians. The automatic control system with Mitsubishi PLC or SIEMENS PLC as the core technology is applicable to various printing and packaging machinery systems. The AP-T13C tension control system is a high-precision and high-reliability control system developed for the development of domestic gravure printing machines. It consists of seven AC vector motors that drive two-position release reels, unwinding traction rollers, The main motor, take-up traction roller, and double-position take-up reel perform tension control. The strop roller is used for tension detection. The PLC performs central control and the touch screen operation can simultaneously complete the automatic reel diameter detection, automatic reel diameter calculation, and reel diameter alarm. Retracting and reeling automatic cutting, taper control, counting length, rewinding and rewinding switch, rewinding/unwinding tension maintaining, fault detection and fault diagnosis information technology, gravure printing machine management technology, long-distance technical support and other functions.
Second, the system requirements
(1) It must be ensured that the material tension in each stage is constant, the speed is synchronized, and the response is fast;
(2) Start and stop should be smooth without impact, and materials must not wrinkle;
(3) When the materials are taken in, the surface speeds of the two rewinding rolls are equal to realize rapid roll change;
(4) The tension in each segment is constant and the amplitude of oscillation of the pendulum is small;
(5) Acceleration and deceleration and operation should be stable, no speed change;
(6) Low frequency torque characteristics, high speed accuracy;
(7) The rewinding and rewinding of the rewinding material is convenient, and there is no tension change to affect the color registration;
(8) necessary protection and easy operation;
(9) The host starts automatic calculation of diameter and material thickness.
The basic composition and characteristics of the three, seven motor tension system - tension control
The system consists of two parts: unwinding, unwinding traction, winding traction, double-station winding tension control and main motor control. The following describes the respective characteristics of these five parts:
The unwinding tension control includes a tension detecting unit, a tension calculating unit, a servo actuator, an automatic reel diameter detecting unit, a pre-drive control, and an automatic cutting control.
(1) The tension detection unit used in the tension control system is an air pressure floating roller tension detection device that detects the film tension by adjusting the air pressure of the cylinder connected to the floating arm of the detection roller. When cylinder air pressure is set, the cylinder thrust on the swing arm is a fixed value. The principle of this control mode is to calculate a matching frequency setting value f1 through the material line speed and the actual coil diameter, and then perform the tension (position) feedback signal. The PID operation produces a frequency adjustment value f2 and the final frequency output is f=f1+f2. F1 can basically match the linear velocity of the take-up/discharge roll with the material linear velocity, and then the f2 part needs only a slight adjustment to meet the control requirements, which well solves the contradiction between rapid response and control stability in closed-loop control. . In the system in equilibrium, when a strong disturbance occurs, such as if the system reacts too late, the tension fluctuation on the material film can be temporarily absorbed by the floating roller. Therefore, the floating roller test is a superior detection method.
(2) We use Japanese Mitsubishi PLC or German SIEMENS PLC as the core of the tension calculation system. It has the characteristics of modularity, high speed, high precision, and strong anti-interference ability, which is very favorable for such complex and high-precision operations as tension. In the mathematical model of the system, due to the use of a special algorithm, the tension fluctuations caused by changes in the speed of the lift and the change in the coil diameter have been compensated in theory, so that the tension during the operation of the hoisting speed or the large or small coil diameter has been compensated. They are all very stable. Even when changing rolls, the tension transition is very smooth. Therefore, the system has reduced the loss of trapping caused by the tension wave to a low level.
(3) The automatic reel diameter calculation unit is a general term for hardware and software that automatically detects the diameter of each new loading reel by the reel diameter automatic detection device and then sends it to the PLC for operation. The unit adopts double-segment broken lines to perform curling simulation, which overcomes the disadvantages of large deviation of curling diameter simulated by the single-segment straight line of imported equipment, which makes the pre-drive speed error smaller and further reduces the tension disturbance during automatic cutting. . Automatic coil diameter calculation unit also sets the minimum coil diameter limit function. When the diameter of the new loading coil is less than a certain limit value, the PLC will limit the continuous execution of the automatic cutting action, which is beneficial to protect the mechanical structure from being damaged.
(4) Pre-drive control and automatic cutting control are the key to smooth switching between new and old materials. This part of the action control is automatically completed by the PLC program. Users only need to operate two buttons to automatically complete the material rack operation and materials. Frame positioning, cutting arm lift, pre-drive, cutting roller pressure, tape position detection, cutting, arm retraction, tension switching and a series of actions.
The basic composition and characteristics of the four and seven motor tension systems - Traction tension control
1. Traction tension control
Traction tension control consists of two parts, namely unwinding tension control and winding tension control. The principle and structure of the two parts are similar. This section includes tension detection unit, tension calculation unit and servo actuator
(1) Tension detecting unit adopts air pressure floating roller tension detecting device
(2) The servo actuator is composed of Japan Yaskawa vector inverter and ABB vector inverter dedicated motor.
(3) In the entire four-stage tension control, the control of the tension tension becomes important, and the control of the tension tension is directly related to whether the overprint is stable. Therefore, the system takes a series of important measures when dealing with the tension signal, so that the pulling tension is very stable throughout the printing process (including the speed of the lift and the cutting process), and the air pressure floating roller can barely observe the swing with the naked eye.
(4) The tension calculation unit uses the Japanese Mitsubishi PLC or the German SIEMENS PLC as the core of the operation system.
2. Winding tension control
This section includes tension detection unit, tension calculation unit, servo actuator, pre-drive control and automatic cutting control.
(1) Tension detecting unit adopts air pressure floating roller tension detecting device
(2) The servo actuator consists of two Yaskawa vector inverters from Japan and two ABB vector inverters.
(3) The tension calculation unit uses the Japanese Mitsubishi PLC or the German SIEMENS PLC as the core of the operation system, and the PLC technical parameters are the unwinding tension calculation unit.
(4) The principle of the tension and rewinding operation unit of the retracting and unwinding is basically the same, and the tension fluctuation caused by the change of the lifting speed and the coil diameter has also been compensated. Therefore, the tension is very stable during the operation of the hoisting speed or the large and small coil diameter. Even when changing rolls, the tension transition is very smooth.
(5) The winding tension includes a non-linear taper tension control. A good taper tension control can achieve a satisfactory effect of winding and effectively overcome the chrysanthemum core, core pull and other phenomena.
(6) Pre-drive control and automatic cutting control are the key to realize the smooth switching between new and old materials. This part of the action control is automatically completed by the PLC program. Users only need to operate two buttons to automatically complete the material rack operation and materials. Frame positioning, cutting arm lift, pre-drive, cutting roller under pressure, cutting, arm retraction, tension switching and a series of actions.
3. Main motor control
The main motor control occupies an important position in the entire tension system. The line speed of the entire system is synchronized with the plate roller driven by the main motor. The stability of the main motor speed directly affects the overprint quality.
(1) The main motor control in this system is composed of Japan Yaskawa Vector Inverter and ABB vector inverter dedicated motor. It adopts closed-loop vector control with encoder (PG) and has superior electrical performance.
(2) In this system, a series of controls such as start, jog, idle operation, speed, stop, and emergency stop of the main motor adopt multi-point operation, which greatly facilitates the use of the user.