超音波振動を用いた歯車歯面の摩擦低減

Friction reduction and lubricity improvement for meshed gears based on ultrasonic oscillation

(Experiment of friction reduction on the tooth frank)

緒言

　大きな動力を伝達する歯車では，歯面にスコーリングまたはピッチングと呼ばれるような種々の破壊的な摩耗や損傷が発生する．そのため歯車要素には高効率化，損傷防止などを目的として潤滑油が供給される．しかし，潤滑油が使えない極限環境，例えば高温下や宇宙空間などの真空中での損傷は著しく，歯車の寿命は地上の1/50に低下することが知られている．以前より加工や組立の分野において2固体間のすべり摩擦を減ずるために接触面を高い周波数で機械的に加振し，相対運動を与えることが行われてきた．そこで，本研究では潤滑油に代わる潤滑方法として超音波振動による摩擦低減効果を用いた歯車歯面の摩擦力低減と潤滑性向上の手法を提案する．
　まず，有限要素解析を用いた歯車，歯車軸の形状設計および装置の組み立てを行い，超音波振動子を歯車軸端に取り付けて加振試験を行い，歯車歯すじ方向の変位振幅が発生していることを確認した．次に，歯車かみ合い中の歯元応力を測定し，超音波振動による歯面の摩擦低減効果を評価した．また超音波加振条件，潤滑条件，歯面荷重，回転速度等の影響について検討した．

Introduction

This study deals with an ultrasonic oscillation method for friction reduction and lubricity improvement in meshed gears. In recent years, the gear is used in critical environments such as in a vacuum chamber or space environment. Thus, instead of using a conventional method, i.e., lubricant oil, a new method of the friction reduction and lubricity improvement is rather demanding. This paper describes frictional experiments for meshed gears oscillated by an ultrasonic actuator which is fixed on the end surface of the gear shaft. Strain gauges are attached on the fillet between the dedendum flank and the bottomland to measure stress conditions during forward and reverse rotations when a constant torque was applied about the gear axis. The friction on the tooth flank is evaluated from the averaged stress difference between the forward and reverse rotations. The study showed that when no lubricant was applied, the ultrasonic oscillation has reduced the friction between tooth flanks by approximately 40% compared to non-oscillation results.
Key Words :Gear, Friction reduction, Lubricity improvement, Ultrasonic oscillation



Fig.Ultrasonic longitudinal vibration propagated in gear shaft


Fig.Experimental setup with three gear shafts


Fig.Experimental setup with three gear shafts


Fig.Effect of ultrasonic oscillation and lubrication on averaged stress difference


Fig.Frictional force ratio with change in amplitude of ultrasonic oscillation

The study showed that when no lubricant was applied, the ultrasonic oscillation has reduced the friction between tooth flanks by approximately 40% compared to non-oscillation results.

印刷論文

  1. 大岩孝彰，牧野陽平，朝間淳一：
    超音波振動による歯車歯面の摩擦力減少と潤滑性向上に関する研究（歯車歯面の摩擦低減実験），
    日本機械学会論文集Ｃ編，Vol. 78 (2012) No. 788 P 1242-1249.
  2. 大岩孝彰，牧野陽平，佐藤元宥，朝間淳一：
    超音波振動による歯車歯面の摩擦力減少と潤滑性向上（歯車軸の設計と試作），
    日本機械学会論文集Ｃ編，77巻775号pp.737-741 (2011).

口頭発表

  1. 牧野陽平，大岩孝彰，朝間淳一：超音波振動による歯車歯面の摩擦力減少と潤滑性向上に関する研究（第3 報），日本機械学会2011年度年次大会講演論文集，S113013（2011）．
  2. Yohei Makano, Takaaki OIWA, Motohiro Sato and Junichi Asama：Friction Reduction and Lubricity Improvement for Meched Gears Based on Ultrasonic Oscillation，The 4th International Conference on Manufacturing, Machine Design and Tribology, ICMDT2011（Gamagori），P-05, 173-174（2011）．
  3. 大岩孝彰，牧野陽平，佐藤元宥，朝間淳一：超音波振動による歯車歯面の摩擦力減少と潤滑性向上に関する研究，日本機械学会第10回機素潤滑設計部門講演会，pp.127-128 (2010).

Papers

  1. OIWA Takaaki, MAKINO Youhei, and ASAMA Junichi: Friction Reduction and Lubricity Improvement for Meshed Gears Based on Ultrasonic Oscillation (Experiment of friction reduction on the tooth frank), TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series C Vol. 78 (2012) No. 788 P 1242-1249.(in Japanese).
  2. OIWA Takaaki, MAKINO Youhei, SATOU Motohiro, and ASAMA Junichi: Friction Reduction and Lubricity Improvement for Meshed Gears Based on Ultrasonic Oscillation (Design and Trial Construction of Gear Shaft), TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series C 77(775), 737-741, 2011(in Japanese).

Conference proceedings

  1. Yohei Makano, Takaaki OIWA, Motohiro Sato and Junichi Asama：Friction Reduction and Lubricity Improvement for Meched Gears Based on Ultrasonic Oscillation，The 4th International Conference on Manufacturing, Machine Design and Tribology, ICMDT2011（Gamagori），P-05, 173-174（2011）．


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