Online ISSN : 2189-9967
Print ISSN : 0915-1168
ISSN-L : 0915-1168
Volume 58 , Issue 3
Showing 1-16 articles out of 16 articles from the selected issue
Serial Messages to Tribologists
Report of Research Group
Essay The Tribo-Soshi, Essays from Tribologists
Original Contribution
  • ― Characteristics of One-Way Rotation and Changing Preload Mechanism ―
    Yasuyoshi TOZAKI, Hiroyuki SONOBE, Takeshi YOSHIMI, Shuichi ISAYAMA
    2013 Volume 58 Issue 3 Pages 170-178
    Published: March 15, 2013
    Released: January 30, 2019

    This paper describes a new low-cost CVT (Continuously Variable Transmission) Micro-Traction-Drive system utilizing commercially available tapered roller bearings. Driving low-cost type CVT to be able to adjust preload were done by arranging loading cam of the slipping method between the two tapered roller bearings combined back to back, the following results were obtained. (1) The expression from which the rotational speed and the flow of power of developed low-cost CVT Micro-Traction Drive systems utilizing tapered roller bearings was clarified. (2) When the load torque is 9 Nm and preload is 196 N, generated preload is about 1600 N. The value of generated preload is mostly in agreement with predicted value when the coefficient of friction on the surface of cam is assumed to be 0.12. (3) Generated preload increase in a linear manner compared with the load torque, and it is proportional relation to the load torque. (4) Hysteresis phenomenon became small since the coefficient of friction was decreased by putting PTFE (Polytetrafluoroethylene) film on the cam surface, and it was confirmed that the coefficient of friction was important factor of hysteresis. (5) The measured transmission efficiency was about 90% at 2 Nm, and efficiency was about 98% at 10 Nm.

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  • ―Scandium Oxide Film, Scandium Nitride Film, and Scandium Nitride Film on Scandium Oxide Film―
    Hiroshi KINOSHITA, Kazuhiro NAGAI, Shogo HARADA, Nobuo OHMAE
    2013 Volume 58 Issue 3 Pages 179-186
    Published: March 15, 2013
    Released: January 30, 2019

    Scandium oxide, scandium nitride, and scandium nitride on scandium oxide thin films were synthesized by the simultaneous irradiation with scandium arc plasma and hyperthermal oxygen and nitrogen atom beams at substrate temperatures of room temperature, 300°C, 500°C, and 700°C. The film characterizations and tribological tests of the scandium composition thin films were carried out. Formations of scandium oxide (Sc2O3) and scandium nitride (ScN) were identified. The scandium oxide films were relatively flat, the scandium nitride films were not flat, and the scandium nitride on scandium oxide thin films except for synthesized at 700°C were relatively flat. It was found that scandium oxide thin films had good tribological properties in vacuum and scandium nitride thin films did in air, and that the tribological properties of scandium nitride on scandium oxide thin films except those synthesized at 700°C were good both in vacuum and in air.

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  • Takafumi YOSHIDA, Masashi HIROTA, Kimito YOSHIKAWA
    2013 Volume 58 Issue 3 Pages 187-196
    Published: March 15, 2013
    Released: January 30, 2019

    The estimation of cage and ball slips in the ball bearings used for the main shafts of jet engines, gas turbines and turbo machines is necessary to clarify the phenomenon of wear and smearing in the bearings. Therefore, in this study, a new method for estimating the cage and ball slips has been developed by taking the lubricating oil to be non-Newtonian fluid, by considering the oil temperature rise caused by slippage occurring in the ball-to-raceway contacts, and by considering the equilibrium of the forces acting between the cage and the balls, which factors were not taken into consideration in HARRIS’ theory. The analytical data of this study have been compared against the experimental data published by POPLAWSKI to establish adequacy of the analysis. The analysis can also calculate the oil film temperature and the traction coefficient.

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  • Norihito MIZOTE, Shin-ichi KURODA
    2013 Volume 58 Issue 3 Pages 197-205
    Published: March 15, 2013
    Released: January 30, 2019

    Hydrogenated amorphous carbon (a-C:H) films were deposited on rubber surface by plasma-enhanced chemical vapor deposition (CVD) using a non-equilibrium atmospheric pressure plasma jet. The effects of additive nitrogen gas in argon working gas on chemical, mechanical and tribological characteristics of a-C:H films were investigated. It is clear that the addition of nitrogen in the working gas causes an increase in nitrogen and hydrogen content of the a-C:H coatings. Furthermore, cracks and wrinkles on the surface of a-C:H films appear due to the addition of nitrogen in the working gas. These changes lead to the improvement of tribological properties such as adhesion between the a-C:H film and the rubber substrate, coefficient of friction and wear resistance. As a result, friction coefficient of 0.13 is achieved when nitrogen is added into argon working gas at a concentration of 16.7 vol%. This plasma process is expected to be an alternative technique to deposit the a-C:H coatings on rubber for conventional methods.

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Report of the Society