A piezoelectric screw-driven motor operating in shear vibration modes

In this study, a piezoelectric screw-driven motor operating in two shear vibration modes is proposed. The working mode of the motor is brand new. Low voltage is sufficient to drive the stator to drive the helical motion of the screw rod, in order to implement high-precision linear motion. The stator structure of this screw-driven motor is formed by obliquely placing four piezoelectric actuators in a four-side hollowed cubic elastic body. A through threaded hole was designed in the z-direction of the stator, exactly fitting the screw rod to be pushed. In the design processes of a screw-driven motor, the finite element analysis software ANSYS was used to analyze the vibration characteristics of the stator structure. The mutually orthogonal z–x and z–y shear vibration modes were designed using ANSYS. The two orthogonal vibration modes are driven by the sine voltage with phase difference between the two sets of piezoelectric actuators. Hence, the stator has elliptical trajectory at the threaded hole edge and drives the screw rod to simultaneously rotate and translate in the axial direction. In the experiment, the screw-driven motor prototype fabricated according to the designed results was measured; it showed that the translational velocity of the screw-driven motor is 2.137 mm/s when applying 16 V peak voltage without mechanical load. The translational velocity of the motor is 1.174 mm/s with 16 g mechanical load under 16 V peak voltage driving.