light industry

introduction
In a lot of automation equipment production process, must ensure that the tension of the processed material is constant, in order to ensure the quality of products and production efficiency. Such as drawing, textile, steel and other industries are reeling, a large number of applications to constant tension control.
Control methods and their characteristics
According to different situations, the control mode can be divided into two ways: closed loop control and open loop control.
1, closed loop control mode
Using the tension detection device directly to detect the material tension, in order to form a feedback loop through the PI operation to achieve a constant closed-loop automatic control mode known as the closed-loop speed control.
Although the correct tension can be obtained with the target value, it is easy to cause the disturbance phenomenon with respect to the short time, so the proportional integral control is needed. The great superiority of the Wei and the frequency converter to the processing of this kind of disturbance.
Features: suitable for application in easy to install tension feedback device system (Zhang Ligan, cylinder swing arm, floating roller), high speed line. Such as micro pull machine, fine pull machine, etc..
In the use of our client's long-term cooperation, we understand that, in closed loop tension control of swing arm system due to long-term in a state of motion, external environment is very bad, so the tension arm cylinder is biggest is vulnerable, and whether it is using displacement sensor or a potentiometer, there are signal attenuation and site disturbance.
2, open loop control mode (no tension feedback)
Open loop is a direct control of the output torque of the motor, the output frequency of the linear speed of the material to follow the automatic change. If the installation of pulse encoder, you can more accurately control the output torque of the motor.
In rolling (rolling), according to the preset empty diameter D1 (full diameter d), linear velocity (V), the material thickness (T) in unit time (s) thickness accumulative calculation to automatically roll diameter measurement and to control the close roll torque and braking torque roll to achieve constant tension control. Within the PLC to establish a closed (on) volume of mathematical models, real-time precise control of the receiving (release) of the motor output torque, to achieve constant tension winding.
The mathematical model of the volume:
D= V D12+4TVtF0/ PI *KB*K
Among them: T - material thickness
KB - plus deceleration inertia compensation
F0 - initial blank tension setting
K - taper coefficient
D1 - minimum diameter
D4 - Max diameter
V - line speed
D - current volume diameter
Compared with the closed loop control mode, it can not produce allergic reaction, and can achieve stable tension control.
Features: suitable for application in the situation can not be installed on the tension feedback device. Through the man-machine interface can be very intuitive to set the relevant parameters.
Here we explain the open loop torque control method.
Two, system configuration
Objective: do not need to do any operation in the inverter. (in addition to a few basic parameters need to be set outside) can be convenient online and intuitive to monitor, roll diameter setting, volume reduction and other operations.
System configuration is as follows:
1, PLC host FX1N-8MR communication module FX1N-485BD
PLC and the main driver of the inverter, the receiving (put) of the inverter for RS485 communication. Communication protocol using RTU MODBUS standard. By setting the volume diameter, material thickness, linear velocity and other parameters in the PLC software to carry out the cumulative thickness of the current volume. According to the current real-time volume calculation of the volume of the (release) roll frequency. Send read and write commands to control the frequency converter operation / stop, output frequency.
2, the touch screen according to the process requirements in the screen parameters bar inside the set of empty, full diameter, material thickness and other parameters. Monitoring the current volume, the cumulative number of meters, output frequency, etc.. Control bar inside the realization of the collection (release) roll function switch, starting and stopping, the volume of the reset, reset parameters, and so on.
3, ECF100-L dedicated inverter host configuration 15KW converter. From the machine (put) volume configuration of 11KW converter. Has good low frequency torque performance. Slip compensation for constant tension control of torque control showed superior characteristics.