IMPROVEMENT OF LUBRICATION LIFE OF GREASE-LUBRICATED STRAIN WAVE GEARING BY CARBURIZING AND TWO-STAGE SHOT PEENING Kazuaki Maniwa (1), Yoshitomo Mizoguchi (2), Akihiro Orita (3) and Shingo Obara (1) (1) Japan Aerospace Exploration Agency, 2-1-1 Sengen, Tsukuba-shi, Ibaraki-ken, Japan, Email:
[email protected] (2) Harmonic Drive Systems Inc., 1856-1 Hotakamaki, Azumino-shi, Nagano-ken, Japan, Email:
[email protected] (3) Asahi Heat Treatment Co., Ltd, 2-9-1 Kuzuhara, Neyagawa-shi, Osaka, Japan, Email:
[email protected] ABSTRACT improved to prolong the lifetime of grease-lubricated SWG under vacuum operation. There are some well- This study investigated a technique to extend the life of known techniques to improve wear resistance under strain wave gearing (SWG) under a vacuum. We boundary lubrication, such as hard coatings and the use applied carburizing and two-stage shot peening to the of new lubricants. In this study, based on fundamental flexspline (FS) inner surface and the FS and circular friction tests and an evaluation of surface properties, we spline (CS) teeth surfaces to reduce wear, particularly at selected a combined surface modification technique— the wave generator (WG)/FS interface. With these carburizing and two-stage shot peening. This technique surface modifications, the FS inner surface was finished was applied to the FS inner surface and the FS/CS teeth to achieve hardness 1.3 to 1.4 times higher than that of surfaces. Surface-modified SWGs were manufactured the WG outer surface, with average roughness of 0.05 to and subjected to a vacuum life test, followed by an µ 0.1 m and surface skewness of -2 to -0.3.