Design And Experimental Study Of Double - Bending Screw - Type Piezoelectric Actuator

Piezoelectric motor is a new type of motor which developed rapidly in recent years. It is based on the converse piezoelectric effect of piezoelectric materials, which makes the motor stator produce vibration. And then the rotor motion is realized through the friction pair between rotor and stator. Due to the driving principle of piezoelectric motors different from traditional electromagnetic motors, it has the advantages of compact structure, small volume and miniaturization. Piezoelectric motor has broad prospects, especially in the fields of aerospace, medical, micro-electromechanical systems(MEMS) and some sensitive to magnetic fields and high precision positioning fields.By combining the precise screw transmission and piezoelectric vibration, a linear piezoelectric actuator is proposed. The actuator mainly utilizes two mutually orthogonal first-order bending vibration modes in the space, which are generated by the free-limiting cylinder. The piezoelectric ceramics are placed at the maximum strain of the cylinder, a driving travelling wave is generated in the inner surface of stator driving end by the superposition of vibration. The output of shaft rotary-linear motion is realized through the screw pairs.Firstly, this paper introduces the structure and working principle of the piezoelectric actuator, including the bending vibration of free beam, the vibration modes of piezoelectric elements, the synthesis of travelling wave at the end surface of the stator, the formation of the elliptical motion of the particle at the end surface of the stator, and the threaded drive mechanism. And the analysis of the actuator driving mechanism provides a theoretical basis for its structure design.Secondly, according to the theoretical analysis, the finite element model of the stator of the actuator is established in the finite element analysis software ANSYS. The influence rules of material parameters and structural parameters on resonant frequency and resonant amplitude were obtained through modal analysis and harmonic response analysis, which is used to optimize the design of the stator structure and determine the specific dimensions of the stator structure parameters.Finally, the prototype actuator and specified power supply were manufactured based on the optimized results, the correctness of theoretical analysis and simulation study was verified through the specific test data. The experimental results show that the actuator has a better mechanical output performance,the maximum no-load speed of the actuator achieves 1.146mm/s and the largest output force achieves2.5N at the case of the driving frequency is 15.8kHz and the operation voltage is 300 V.