Study of measurement method for large imbalance evaluation based on dynamic electromagnetic force

While identifying the imbalance of the workpiece with large eccentric mass, grave error would be produced due to failing to guarantee the linearity of both the balance machine and measuring system. A method was present to improve the measurement accuracy of imbalance identification. It utilized a controllable electromagnet that generated the controllable electromagnetic force to attenuate the unbalance vibration synchronously, so as to avoid the vibration signal exceeding the liner range. Model of equivalent magnetic circuit of the electromagnet was established, and the relationship between the coil current and the dynamic electromagnetic force was analyzed by finite element modeling. The influence on the electromagnetic force of some factors such as temperature and air gap was investigated. The control system and strategy were also developed. Test results indicated that this method is applicable for large imbalance evaluation with high precision.