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US 5,292,200 AGranted
Ball-and-roller bearing
AssigneeNsk Ltd.
InventorsYoichi Matsumoto, Kenji Yamamura, Kousuke Nonaka
Life of this patent
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AssigneeNsk Ltd.
InventorsYoichi Matsumoto, Kenji Yamamura, Kousuke Nonaka
Estimating the term…
At least one of the inner race, the outer race and rolling elements in the improved ball-and-roller bearing is made of an alloy steel that contains 0.1-1.2 wt % of C, 3.0-18.0 wt % of Cr, 0.01-1.5 wt % of Si, 0.3-1.5 wt % of Mn, up to 2.5 wt % of Mo, up to 0.002 wt % of O.sub.2 and up to 0.015 wt % of S and which is subjected to plasma-assisted carburization to such an extent that the relative surface carbon area is at least 15% the surface carbon concentration is in the range of 1.6-3.5 wt % and the amount of surface retained austenite is in the rang of 20 vol %-45 vol %. The bearing can work effectively for a prolonged lifetime even if it is placed under hostile conditions as exemplified by an increased areal pressure of load and entrance of foreign matter into lubricating oils.
A ball or roller bearing comprising an inner race, an outer race and rolling elements, at least one of said inner race, said outer race and said rolling elements being made of an alloy steel that consists of 0.1-1.2 wt % of carbon, 3.0-18.0 wt % of chromium, 0.01-1.5 wt % of silicon, 0.3-1.5 wt % of manganese, up to 2.5 wt % of molybdenum, up to 0.002 wt % of oxygen, up to 0.015 wt % of sulfur and the balance being iron and incidental impurities, at least one of said inner race, said outer race and said rolling elements being subjected to plasma-assisted carburization and hardened to such an extent that it has a relative surface carbon area of 15-45%, a surface carbon concentration of 1.6-3.5 wt % and a surface retained austenite level [.gamma..sub.R ].sub.sur of 20-45 vol %.
Dependencies are inferred from the claim text.