How to use a magnetic powder clutch with a tension controller

Manual Tension Controller Overview:

　　In the winding process of many industrial production materials, due to changes in the material coil diameter and other factors, the material tension is constantly changing. In order to keep the material tension consistent, it is necessary to adjust the damping device's resistance torque or winding torque in time.
　　At the unwinding end, the tension of the unwinding material is determined by the torque of the magnetic powder brake installed at the unwinding end; at the winding end, the winding tension is determined by the transmission torque of the magnetic powder clutch. In order to maintain consistent tension, the transmission torque must be increased or decreased according to the size of the coil diameter. Tension control is divided into manual control and automatic control. The manual tension controller, which is a constant current power supply, manually adjusts the excitation current of the magnetic powder brake or magnetic powder clutch in stages according to the changes in the unwinding or winding coil diameter, thereby obtaining consistent tension.

So-called tension control, simply put, is to be able to control how much force the motor outputs, that is, how many Newtons it outputs. Reflected on the motor shaft, it means controlling the motor's output torque.
　

How can the torque of the magnetic powder clutch and brake be controlled with high precision?

Magnetic Powder Clutch and brake are not only used for low-tension single-axis control, but are also often used in multi-shaft synchronous control using multiple units on one machine. By correcting the mechanical friction between the various shafts and the differences in characteristics of the magnetic powder clutches and brakes that occur in this control, a stable control effect is achieved.

Tension control applied in the tension control system of a gravure printing machine is essentially a special servo system where the input quantity changes according to a certain adjustable attenuation law. Tension control can be said to be the core of the entire machine control. As long as the tension control is stable and the tension change is small, the color registration accuracy and defect rate of the gravure printing machine are easy to control.

　Power amplifiers are used in tension control devices for wire, paper, and film manufacturing machines, etc., which are special power amplifiers that control the magnetic excitation current of DC24V series magnetic powder brakes, magnetic powder clutches, and miniature magnetic powder brakes. Constant current control can be adopted, even if the temperature change of the magnetic powder clutch and brake causes the coil resistance to change. By controlling the output current to a constant value, the generated torque remains constant, thereby achieving stable and high-precision control.

Using a variable frequency drive for constant tension control essentially involves a closed-loop vector control, i.e., adding encoder feedback. For winding, the winding diameter changes from small to large. To ensure constant tension, the motor's output torque must change from small to large. At the same time, corresponding torque compensation must be performed during different operations. That is, at the moment of starting a small roll, acceleration, deceleration, and stopping, when starting a large roll, different torque compensation must be performed at different winding diameters, so that the entire winding process can be very stable, avoiding excessive tension when the roll is small; and the phenomenon of loose yarn when starting a large roll.

 

Application Range

　　Papermaking, adhesive tape production, paper processing, wire and cable, printing industry, film, photographic film industry, textile industry, rubber industry, metal foil processing, fiber industry, leather industry, optical fiber manufacturing