The coating machine for packaging and printing is mainly composed of discharge unit, storage unit, coating unit, composite unit and receiving unit (as shown in Figure 1). The tension control system consists of discharging unit, discharging storage rack, gluing unit, receiving storage rack and receiving section. This paper briefly analyzes the tension detection and control system of coater, and introduces the method to keep the tension stable in the coating process.
Tension detection of 1 coater
The tension of coating machine is detected by swinging roller and potentiometer, which are connected by gears.
Set each end of the potentiometer as P +, u, P -, pg,
Voltage value: between P + and PG is + 10V, between P - and PG is - 10V.
When tension set value = tension feedback value, the voltage between u and PG is 0V;
When the tension value changes, that is, the swing roll swings, the voltage between u and PG changes, so as to detect the tension and effectively control the tension stability.
2 tension control of discharging unit
Coater is generally equipped with two discharge units.
(1) The first discharging unit is passive discharging. The unit is very mature and the tension can always be stable.
(2) The second discharging unit is active discharging. In the process of discharging, the diameter of the unwinder is decreasing, and the tension of the discharging swing roller is controlled by PLC and PID controller.
The PLC controller can calculate the unwinding diameter and control the corresponding motor to accelerate continuously to keep the tension stable; the PID controller can calculate and realize the fine adjustment of the speed of the unwinding motor to ensure the tension stability when the position of the unwinding swing roller is offset.
3. Tension control of discharging storage rack and discharging process
The discharging and storing rack can realize zero speed feeding during discharging. Before the start-up of the equipment, the state of the discharging and storing rack should be checked to ensure that the discharging and storing rack is full of the base material and ready for discharging.
When the discharging unit needs to be refueled, press the receiving button, the discharging storage rack motor accelerates and the discharging traction motor decelerates. In this process, the discharging traction swing roller controls the discharging traction motor, and the discharging storage frame motor follows the speed of the host machine. When the speed of the discharging storage frame = the speed of the host machine, the speed of the discharging traction motor drops to 0. At this time, the feeding traction swing roller is switched from the original control of the feeding traction motor to the control of the feeding storage frame motor, so as to ensure the stable feeding tension and smooth zero speed feeding.
After finishing the discharging work, press the receiving completion button, the discharging storage frame motor decelerates and the discharging traction motor accelerates. At the same time, the discharging traction swing roller starts to control the discharging traction motor. When the discharging storage frame motor speed decreases to 0, the discharging traction motor speed = the host speed.
The discharging and storing rack starts to raise and store materials at zero speed until it rises to the set speed. At this time, the speed of the discharging traction motor = the speed of the main machine + the rising speed of the discharging storage rack, which meets the tension stability of the process.
When the storage is completed, the motor of the discharging and storage rack starts to decelerate at a constant speed until the speed is zero. The discharging traction motor decelerates, and when the discharging storage rack motor drops to 0, it drops to the same speed as the host.
4 tension control of coating unit
The circumference of the cot is fixed, so the speed of the cot motor is the speed of the host machine plus the adjusting speed of the swing roll. The internal PID controller of Yaskawa h1000 inverter can meet the tension fine-tuning control from gluing unit to composite unit.
5. Tension control of receiving storage rack and receiving process
The coater process is diverse, and the pre drive shaft is required to be in a static state when receiving. Therefore, the coater should have a receiving and storage frame mechanism. Before the start-up of the equipment, the position of the receiving and storage rack should be checked first, and the storage rack should be adjusted so that it can automatically drop to the lower end of the storage mechanism at a certain speed and be ready to receive the material.
When the receiving shaft needs to be refueled, press the receiving button, and the receiving storage frame will accelerate from zero. At the same time, the receiving traction and the current receiving shaft will decelerate. In this process, the receiving traction swing roller controls the receiving traction motor, and the receiving storage frame motor follows the speed of the host machine. When the speed of the receiving storage frame motor = the speed of the host machine, the speed of the current axis of the receiving traction and receiving is reduced to 0. At this time, the feeding traction swing roller is switched from the original control of the feeding traction motor to the control of the storage frame motor, so as to ensure the stable feeding tension. Then, the receiving turret performs corresponding actions to complete the receiving work.
After the receiving action is completed and the receiving arm falls down, the motor of the receiving storage rack decelerates, the receiving traction and the current axis of the receiving are accelerated. In this process, the receiving traction swing roller controls the receiving traction motor. When the speed of the receiving storage frame motor is reduced to 0, the speed of the receiving traction motor and the current axis of the receiving is equal to the speed of the host machine.
The receiving storage rack accelerates downward at zero speed until it reaches the set speed. At this time, the speed of the receiving traction motor and the current axis of the receiving is equal to the speed of the host machine + the descending speed of the receiving storage rack, so as to meet the stable tension from the composite unit to the receiving storage rack and from the receiving storage rack to the receiving unit.
When the receiving and storing rack descends to the deceleration mark, it begins to decelerate at a constant speed until the speed is zero. The front axle of receiving traction and receiving also decelerates, and when the speed of receiving storage rack drops to 0, the speed drops to the same speed as the host.
