Manual Control: During material take-up and unload, the torque of the clutch or brake is continuously adjusted to obtain the required tension. This requires the user to constantly check the tension of the controlled material and adjust the output torque accordingly. If a pneumatic brake or clutch is used, a precision pressure regulating valve can be directly selected for the manual controller, saving the user some equipment costs. However, this method is only suitable for low-speed laminating machines, extruders, textile machinery, and other applications where tension control requirements are not high.
Semi-Automatic Method: Utilizes ultrasonic principles to automatically detect the roll diameter and adjust the roll tension accordingly. For example, the Montalvo U3500 ultrasonic tension controller is essentially a semi-closed-loop tension control system. It not only automatically measures the roll diameter and controls the torque output but also has functions such as buffer start, anti-loosening, and inertia compensation. This solution has a lower implementation cost and is therefore widely used in mid-range machinery.
Fully Automatic Method: Generally, there are two detection methods. One is to measure the tension of the roll material using a tension sensor, and then the controller automatically adjusts the clutch or brake to control the roll tension. This method is a fully closed-loop tension control. In principle, this scheme can reflect the changes in tension in real time, so the control accuracy is the highest. Therefore, some high-end finishing mills, high-speed slitting machines and other metallurgical applications use fully automatic tension control systems.