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Description
The conventional ring-spinning process has been used for over a century, being one of the most used processes in the textile industry. However, this process has some disadvantages at high spindle speeds, such as friction in the traveler/ring components that generates heat, resulting in yarn breakages or lower-quality production.
New technological advances like superconducting magnetic bearings (SMB) systems have been implemented to face the limitations in the spindle speed. The SMBs use superconductors and permanent magnets to achieve magnetic levitation, decreasing in this way drastically the friction and enabling spindle speeds up to 50,000 rpm.
Previous studies have investigated SMB dynamics, and it has been proved that the mathematical model for a six-dimensional motion can be reduced into a second-order ordinary system in matrix form that consists of a mass, stiffness, and damping matrices, but due to the freedom given by the magnetic levitation, there is the presence of oscillations in the permanent magnet due to external forces. A recent study implemented an Eddy Current Damper (ECD) based on copper rings that increase the damping coefficients, resulting in the reduction of oscillations in the permanent magnet.
In this contribution, the study of the SMB with ECD is extended to analyze the frequency response in all directions of movement for different cases of thicknesses of the copper rings. During the theoretical analyses, it was deduced that the natural frequency in the tilting angles split into two distinct natural frequencies, which is characteristic of spinning disks due to gyroscopic effects.
Experiments were conducted in an SMB tester, and the motion of the permanent magnet was captured using laser position sensors. The oscillations were measured for different angular velocities to study the resonance frequencies involved during the acceleration phase. Then, parametric identification was performed to determine the stiffness and damping coefficients for all the copper ring configurations. Forces and torques due to external forces were estimated based on the model.
