Friction control based on ultrasonic oscillation
for rolling element linear motion guide

Introduction

In recent years, demand has accelerated for highly accurate guide elements such as those used in measurement instruments and precision machine tools. Aerostatic bearings utilizing thin films of high-pressure air supporting a load have been widely used for precision positioning and high-speed applications.1 However, the most important problem with aerostatic bearings is their lack of stiffness and damping given the compressibility and very low viscosity of air. This problem has not been fundamentally settled, not even by using actively controlled air bearings.

Linear motion rolling element bearings have a high degree of stiffness and damping as compared with air bearings. These mechanical contact bearings also have a low friction coefficient as compared with sliding contact bearings. Usually, the static and dynamic coefficients of friction are almost equal. However, high static friction with lower dynamic friction results in stick-slip or stiction, wherein the coefficients are separated and the difference between them increases with increasing preload.1 The stick-slip motion and stiction become a serious problem for a positioning device when sub-micrometer order positioning resolution is required. If the static friction generated at low velocity is reduced to the same level as the dynamic friction, the stiction will be successfully prevented.

This study investigates a method of friction control for the rolling element linear motion guide which is based on ultrasonic oscillations. The ultrasonic vibration has been used to reduce the friction force in many applications, including ultrasonic machining, the inserting operation of mechanical parts, and the feeding of thin films or papers.




Fig.Generated frictional forces in rolling element linear motion guide


Fig.Linear guide rail oscillated by ultrasonic actuator



Fig.Linear guide rail oscillated by ultrasonic actuator


Fig.Experimental results of static and Dynamic frictional forces with/without oscillation

The experiments using a force sensor showed that the static and dynamic friction forces were reduced by approximately 25 % at any place on the 600-mm long rail. Moreover, excitation only at very low velocity decreased the static friction from 21 N to 13 N.


Papers

  1. Hashim Syamsul, Takaaki Oiwa, Toshiharu Tanaka, Junichi Asama: Positioning error improvement based on ultrasonic oscillation for a linear motion rolling bearing during sinusoidal motion, Precision Engieering, In-press
  2. Takaaki OIWA: Friction control using ultrasonic oscillation for rolling element linear motion guide, Review of Scientific Instruments, Vol. 77, 016107 (2006) pp. 1-4.



Proceedings

  1. Hashim Syamsul, Takaaki Oiwa, Toshiharu Tanaka and Junichi Asama: Investigation on nonlinear spring behavior subjected to ultrasonic oscillation for a rolling-element linear guideway, Proceedings of The 5th International Conference on Manufacturing, Machine Design and Tribology(ICMDT2013) , BEXCO, Busan, Korea,22-25May,2013, pp.C6-03
  2. Hashim Sy Syamsul, Takaaki Oiwa Takaaki, Toshiharu Tanaka, Kenji Terabayashi and Junichi Asama: Friction Control Based on Ultrasonic Oscillat Oscillation for on Rolling Element Linear Guideway- Improvement of Position Tracking acking Accuracy inSinusoidal Motion -, The 5th International Conference on Positioning Technology 2012,November 14-16, 2012,Garden Villa, Kaohsiung City, Taiwan
  3. Takaaki Oiwa and Khairul Aizat: The 3rd International Conference on Positioning Technology 2008, pp.261-266, 2008.11 Congress Centre, Hamamatsu, Shizuoka, Japan 2008.11.27

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