固结磨料超声磨削用压电换能器等效阻抗分析

固结磨料超声磨削加工过程中,随着负载的快速变化,压电换能器必须保持快速的频率跟踪与功率匹配响应,才能满足高效精密加工需求。该文从微观角度分析了固结磨料超声磨削的材料去除过程,通过建立压电换能器的力学模型,基于力电类比,得出压电换能器的等效阻抗与负载变化关系,即换能器的负载越大,其等效阻抗越大。当采用恒压源驱动压电换能器时,当换能器的负载越大,输出功率越小;反之,负载越小,输出功率越大,换能器无法工作在最佳状态。因此,为改善加工稳定性,提高材料表面完整性,提出了压电换能器的智能化恒流激励电源驱动方案,并进行了空载和负载状况下的电源系统测试试验,为进一步展开相关加工工艺研究奠定了坚实的基础。

Analysis on the Equivalent Impedance in Piezoelectric Transducer for Ultrasonic Assisted Fixed Abrasive Grinding

During the process of ultrasonic assisted fixed abrasive grinding, the fast frequency response and power matching of piezoelectric transducer are necessary in accordance with the quick change of the load, which is an efficient approach for precision machining. In this paper, the material removal mechanism of ultrasonic assisted fixed abrasive grinding is analyzed from microscopic view. With the establishment of mechanical model of piezoelectric transducer, the relationship between equivalent impedance and load is obtained by using mechano electrical analogy, i.e. the heavier the load, the higher the equivalent impedance is. Unfortunately, when a constant voltage source is applied on piezoelectric transducer, the heavier the load, the lower power output is, vice versa. Hereby, in order to improve the stability of working conditions and surface integrity of workpiece, a method of intelligent constant current excitation power is proposed, and is investigated on unloaded and loaded conditions experimentally, which lays a strong foundation for further research on relative processing technologies.