A study on the friction and thrust force of the shaft and mobile element in the impact typed piezoelectric ultrasonic linear motor

Abstract

Recently, a novel tiny piezoelectric ultrasonic linear motor driven by impact force which converts a radial mode vibration into a longitudinal one was developed for camera optical modules. This tiny piezoelectric motor consists of a shaft, mobile element and piezoelectric transducer. In this work, the frictional properties of the interface between the shaft and mobile element were investigated according to their respective materials. Five types of materials were used for the shaft, viz. stainless steel coated with DLC (Diamond like carbon) and PTFE (Polytetrafluoroethylene), uncoated stainless steel, Pyrex and Graphite. Bakelite and stainless steel (SUS) were used for the mobile elements. It was found that two combinations, namely Pyrex glass or stainless steel for the shaft and stainless steel for the mobile element, exhibited good dynamic behaviors in a tiny piezoelectric ultrasonic linear motor, which was newly developed based on operating concepts based on Newton's law.