Gravure printing machine tension control are basically manual tension control, open-loop and closed-loop tension control semi-automatic Automatic tension control three categories. 
  Manual tension control is in the process of winding or unwinding, when the roll diameter changes to a certain stage, by the operator to manually adjust the power supply unit, so as to achieve the purpose of controlling the tension. But modern gravure printing machine manual tension control system has basically been eliminated, but merely exist as a closed-loop automatic tension control system of an operating mode. 
Open-loop tension control, also known as semi-automatic tension control roll diameter detection, which is installed in the proximity switch at reel, reel speed is detected, and through the reel diameter and material thickness initial value set, the cumulative calculable rewinding or discharge current roll diameter and roll diameter of a corresponding variation in the output control signal to control the winding or unwinding torque braking torque, to adjust the tape tension. Because each revolution of the reel, two-fold variation in the thickness of the tape roll diameter occur. Such tension control is not affected by external stimuli, can carry a stable tension control. However, due to changes in factors torque transmission device, a linear variation and mechanical wear and tear, such tension control absolute accuracy is poor. 
Closed-loop control of the automatic tension measured value of the actual tension of the strip directly from the tension sensor, and then converts the data into a tone signal back tension of the tension controller, the tension value of this signal by comparison with the preset controller calculates the control signal, the automatic control of the execution unit so that the actual value and the preset tension value of the tension equal to the tension stabilized to achieve the purpose. It is currently more advanced tension control methods....