A Study on Characteristics of Flow Field of Air Gap in Maglev Spherical Active Joints for Multi-DOF Spindle System
Realizing six-degree-of-freedom movement for spindle tools in any posture is an important research direction for CNC machines. Existing spindle systems with parallel or cascaded structure, due to their complex mechanical structure, lead to serious abrasion on mechanical supports when rotating at a high or ultra-high-speed, which heats joint parts and worsens the dynamic characteristics. In light of technologies of motor and magnetic levitation, this paper proposed a multi-degree-of-freedom machine spindle system built on a maglev spherical active joint, and analyzed working principles of a three-dimensional rotating magnetic field generated by the rotor of maglev spherical active joint rotating around an arbitrary axis passing through a fixed spatial point. This paper also explored the effects of flow field of air gap formed in the maglev spherical active joint on the dynamic & static characteristics of joint based on aerodynamics, established mathematical models for the dynamic & static pressures and kinetic parameters of flow field of air gap, and, with simulation and experiment, investigated how the flow field of air gap impacts the static load-carrying capacity and the dynamic characteristics of joint.