Akira Ishibashi

Investigation of the Noise and Vibration of Planetary Gear Drives

With the aim of reducing the operating noise and vibration of the planetary gearsets used in automotive automatic transmissions, a meshing phase difference was applied to the planet gears that mesh with the sun and ring gears. Shaved and hardened helical gears with and without grinding were used as the component gears that were tested under varying rotational speeds and tooth loads. The experimental results clearly showed that planetary gearset noise and vibration were reduced when a meshing phase difference was applied.Copyright

Performance of used engine oil as gear-cutting oil

In Japan, the lubricating oil used for the internal combustion engine of passenger cars is usually exchanged for fresh oil after running a distance in the range from 3,000 to 10,000 km. Refining of the used engine oil is very costly because friction-reducing additives containing sulfur, phosphorus, etc., are included in the oil. Therefore, wasted engine oil (used engine oil) is burned in many cases. This investigation was conducted to effectively re-use wasted engine oil without chemical refining. Performance of used engine oil as a gear-cutting oil was examined by conducting five kinds of experiments: (a) chemical analyses of the oils, (b) measurements of friction coefficients on the four-ball tester, (c) tool wear tests using a lathe, (d) tool life tests using a gear-cutting machine, and (e) accuracy and surface finish of the cut gears. In contrast to general expectations, longer tool lives were obtained when the used engine oils were used instead of a high-grade gear-cutting oil. The reason for this was discussed and it was concluded that used engine oil may be used as a high-performance gear-cutting oil if health risks for workers are removed.

Effect of Case Hardening by Ion Nitriding on Impact Fatigue Strength of High Tension Steel.

Ion nitriding has been used to improve the wear resistance of machine elements such as gears, rollers, etc.. However, it is scarcely known that ion nitriding causes an appreciable reduction in bending impact fatigue strength.Together with the conventional tension and Charpy impact tests, the cyclic impact tests were carried out to clarify the effect of case hardening by ion nitriding on the bending impact fatigue strength of a high tension steel (HT80), where a low carbon alloy steel (SM50) was used as a reference material. In the case of the low carbon alloy steel with a tensile strength of about 500MPa, ion nitriding reduced the impact fatigue life to about one tenth of the same steel without nitriding. The reduction ratio became smaller (about 1/3) in the case of the high tension steel with a tensile strength of about 800MPa. The impact fatigue strength of nitrided steel is closely related to the impact resistance determined by the Charpy impact test.