Rolling bearing
AssigneeNsk Ltd.
InventorsHiromichi Takemura, Akihiro Kiuchi, Yasuo Murakami
Life of this patent
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Abstract
An outer ring 2 as a stationary ring is fabricated with an iron-steel material of the following composition. Alloying components contain carbon (C) 0.40 wt % to 1.20 wt %, silicon (Si) and/or aluminum (Al) 0.7 wt % to 2.0 wt %, manganese (Mn) 0.2 wt % to 2.0 wt %, nickel (Ni) 0.1 wt % to 3.0 wt % and chromium (Cr) 3.0 wt % to 9.0 wt %. Cr-equivalent amount shown in the following (1) formula is 9.0 wt % to 17.0 wt %. In the bearing face, the hardness is HRC57 or higher, fine carbides (diameter 50 to 500 nm) are dispersively precipitated, and the maximum diameter of carbide is less than 10 μm. Cr-equivalent amount (%)=[Cr]+2[Si]+1.5[Mo]+5[V]+5.5[Al]+1.75[Nb]+1.5[Ti] (1).
Claims12
A rolling bearing comprising:
- a stationary ring;
- a rotary ring;
- and
- a plurality of rolling elements rotatably interposed between said stationary and rotary rings,
- at least said stationary ring is made of an iron-steel material containing alloying components of:
- 0.40% to 1.20% by weight of carbon (C);
- 0.7% to 2.0% by weight of at least one of silicon (Si) and aluminum (Al);
- 0.2% to 2.0% by weight of manganese (Mn);
- 0.1% to 3.0% by weight of nickel (Ni) and
- 3.0% to 9.0% by weight of chromium (Cr),
- where Cr-equivalent amount defined by following formula (1) is 9.0 wt % to 17.0 wt %,
- Cr-equivalent amount (%)=[Cr]+2[Si]+1.5[Mo]+5[V]+5.5[Al]+1.75[Nb]+1.5[Ti] (1)
- in the formula, [Cr], [Si], [Mo], [V], [Al], [Nb] and [Ti] show containing percent (wt %) of Cr, Si, Molybdenum (Mo), Vanadium (V), Al, Niobium (Nb) and Titanium (Ti) in the iron-steel material, and
- wherein said at least said stationary ring has a rolling surface which is subjected to quenching and tempering and has hardness of HRC 57 or higher,
- wherein at least said stationary ring further comprises:
- at least one of V, Nb and Ti, while satisfying a condition that V≦2.0 wt %, Nb≦1.0 wt %, and Ti≦1.0 wt %, and
- wherein a maximum diameter of carbide existing in the rolling surface of at least said stationary ring is less than 10 μm,
- wherein average diameter of fine carbide existing in the rolling surface of at least said stationary ring is 71 to 475 nm, and
- wherein the average diameter is defined by (maximum diameter+minimum diameter)/2 (nm).
A rolling bearing comprising:
- a stationary ring;
- a rotary ring;
- and
- a plurality of rolling elements rotatably interposed between said stationary and rotary rings,
- at least said stationary ring is made of an iron-steel material comprising alloying components of:
- 0.40% to 1.20% by weight of carbon (C);
- 0.7% to 2.0% by weight of at least one of silicon (Si) and aluminum (Al);
- 0.2% to 2.0% by weight of manganese (Mn);
- 0.1% to 3.0% by weight of nickel (Ni) and
- 3.0% to 9.0% by weight of chromium (Cr),
- where Cr-equivalent amount defined by following formula (1) is 9.0 wt % to 17.0 wt %,
- Cr-equivalent amount (%)=[Cr]+2[Si]+1.5[Mo]+5[V]+5.5[Al]+1.75[Nb]+1.5[Ti] (1)
- in the formula, [Cr], [Si], [Mo], [V], [Al], [Nb] and [Ti] show containing percent (wt %) of Cr, Si, Molybdenum (Mo), Vanadium (V), Al, Niobium (Nb) and Titanium (Ti) in the iron-steel material, and
- wherein at least said stationary ring further comprises:
- at least one of V, Nb and Ti, while satisfying a condition that V≦2.0 wt % Nb≦1.0 wt %, and Ti≦1.0 wt %, and
- wherein average diameter of fine carbide existing in the rolling surface of at least said stationary ring is 71 to 475 nm, and
- wherein the average diameter is defined by (maximum diameter+minimum diameter/2 (nm).
The rolling bearing as set forth in claim 10, further containing:
- 10 ppm or less of O;
- 0.02% or less by weight of S;
- and
- 0.02% or less by weight of P.
Dependencies are inferred from the claim text.