| 摘要 |
PROBLEM TO BE SOLVED: To improve very-long service life fatigue fracture strength of a toroidal-type continuously variable transmission. SOLUTION: At least one of an input disc 2, an output disc 3 and a power roller 5 of this toroidal-type continuously variable transmission is constituted by processing a material composed of steel including C of 0.15 - 0.5 mass%, Si of 0.1 - 1.5 mass%, Mn of 0.1 - 1.5 mass%, Cr of 0.5 - 3.0 mass%, Mo and Ni of 0.1 - 3.0 mass% in total, Fe and unavoidable impurities as remaining parts, and having a content of O of 9 ppm or less, and a content of H of 0.03 ppm or less, into the predetermined shape. Then the heating treatment including vacuum carburizing treatment is performed to achieve a content of C on surfaces of power transmitting faces 2a, 3a, 5a of 0.8 - 1.2 mass%, surface hardness of Hv680 or more, residual stress of the surface of -200 to -1500 MPa, a crystal grain size of the surface of 10 or more, a crystal grain size of a core part of 8 or more, and a thickness of an internal oxidation layer of 5μm or less. COPYRIGHT: (C)2005,JPO&NCIPI
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