Development of MR fluid composite brake and its application to wire tension control system for coil winding

Magnetorheological (MR) fluid behaves like a Bingham fluid having yield stress, which can be rapidly changed in a reversible manner by applying magnetic field. In this research, for the purpose of developing the wire tension control device for coil winding, a novel MR fluid composite brake with no rotating part to control the wire tension has been developed and the characteristics of the braking force have been measured. The developed MR brake consists of an electromagnet of rectangular shaped magnetic pole and a narrow slit perpendicular to the magnetic pole where two pieces of sponges containing the MR fluid; MR fluid composites are inserted into. The wire directly goes through between the two pieces of MR fluid composite, receiving the braking force that can be changed by applied magnetic field to the MR fluid composite. And then, a PID tension feedback control system using the developed MR fluid composite brake is constructed, and the tension control characteristics for winding of a non-circular coil are investigated. The developed MR tension control system performs the drastic reduction of the wire tension fluctuations, compared with a conventional mechanical tension control system.