Friction Characteristics of Microstructured Surface Created by Whirling Electrical Discharge Texturing

ふれまわり放電テクスチャリングによる創成された微細表面の摩擦属性

2014-09-25

2014-09-25

Whirling electrical discharge texturing (WEDT) was developed for creating microstructures on the inner surface of small cylinder to confirm the surface characteristics of textured surface by controlling the machining conditions of WEDT. In addition, the tribological characteristics in terms of friction characteristics of non textured and textured suface were evaluated through ball-on-disc and pin-on-disc friction tests in order to optimize the optimum surface characteristics of textured surface as well as friction test conditions. Moreover, the friction characteristics of textured surface on the inner surface of cylinder were investigated through reciprocating friction test. In chapter 2, the authors describes the principle of Electrical Discharge Machining (EDM), Electrical Discharge Texturing (EDT) and Whirling Electrical Discharge Texturing (WEDT) which developed from EDM and EDT for generating microstructures on inner surface of small cylinder. The fundamental of WEDT process, WEDT equipment and the preliminary experiment of texturing process were investigated in order to confirm the WEDT method. It was clarified that the microstructures could be generated and controlled on inner surface of small cylinder using WEDT. In chapter 3, it was clarified that a single discharge could be generated with a pulse frequency of 20 kHz and discharge duration of 5 s. The surface characteristics of textured surface were able to be controlled by machining conditions of WEDT. The texture-area ratio and the total removal volume of crater were mainly depending on feed speed and pulse frequency. In addition, crater diameter and crater depth were mainly depending on discharge current. Furthermore, it could be clarified that a good surface quality could be obtained by WEDT. Chapter 4 describes the tribological characteristic in term of friction coefficient was studied through friction test devices which are ball-on-disc friction test, It was investigated that the texture-area ratio of approximately 6% and a mean crater diameter 50 m were suitable conditions to reduce friction coefficient in ball-on-disc friction disc Chapter 5 discuss the effect of the lubrication region, the actual contact surface area, and the surface characteristics of textured surface to friction characteristics was investigated through pin-on-disc friction test. A mean crater diameter 35 m with texture-area ratio of approximately 6% and 4 % with were considered as suitable conditions for reducing the friction coefficient under the mixed lubrication condition near the boundary condition and mixed lubrication condition near the elastohydrodynamic lubrication condition, respectively. Chapter 6 is the main part of this research to reduce the friction coefficient with textured surface on inner surface of cylinder. With reciprocating friction test, low friction coefficient could be obtained under normal load 500 gf with a mean crater diameter of 40 m and texture-area ratio of approximately 2 %. It was clarified that the low friction coefficient could be obtained with optimal condition of surface characteristics and surface roughness of textured surface compare to non textured surface. It was thought that the optimal condition of textured surface to reduce friction coefficient depends on schematic of test specimens, friction test conditions and friction test devices

博士(工学)

京都工芸繊維大学

14303甲第722号

http://hdl.handle.net/10212/2224

en

none

Thesis or Dissertation

Thesis