Nsk Corporation

Kenji Yamamura

Susumu Tanaka

Manabu Ohori

Manabu Obori

Nobuaki Mitamura

Shigeru Okita

Kyozaburo Furumura

Akihiro Kiuchi

Yoichi Matsumoto

Takashi Nagato

Hiromi Sugi

Kousuke Nonaka

Shuji Wada

Masaaki Takagi

A rolling bearing having excellent corrosion resistance and having a long life for use in airplanes is provided. The constituent parts of the rolling bearing are made from an alloy steel containing Cr which is required for the improvement of a rolling contact fatigue life at a high temperature and is most effective for providing steels with corrosion resistance when 7.0% or more to 16% or less on a weight percent basis is provided. The amount of a residual austenite on the surface of the completed product is from 6% or more and, preferably, 35% or less by stabilizing the residual austenite.

Rolling bearing

An inexpensive rolling apparatus improved in resistance to fretting, acoustic performance, resistance to corrosion, life and workability is provided. At least one of an outer member, an inner member and rolling elements of the apparatus is formed of an alloy steel containing 1.5% by weight or less of C, 10% to 20% by weight of Cr, 0.1% to 0.8% by weight of Mn, 0.1% to 1.0% by weight of Si and less than 0.2% by weight of N, particularly, at least one of the outer member, the inner member and the rolling elements is formed of a martensitic stainless steel containing 0.6% by weight or less of C, 10% to 14% by weight of Cr, 0.1% to 0.8% by weight of Mn, 0.1% to 1.0% by weight of Si, less than 0.2% by weight of N, 0.5% by weight or less of Mo, 0.2% by weight or less of V, and Fe and inevitable components as the balance, wherein the relationship between the content of C and that of Cr satisfies C %&lE;&minus;0.05 Cr %&plus;1.41; the relationship between a specific relational equation eq1 indicating the content of elements accelerating the conversion of the raw material to ferrite, taken as (eq1)&equals;Cr %&plus;Si %&plus;1.5 Mo %&plus;3.5V %, and a specific relational equation eq2 indicating the content of elements accelerating the conversion of the raw material to austenite, taken as (eq2)&equals;C %&plus;0.83 N %&plus;0.1 Mn %, satisfies (eq2)&gE;0.04&times;(eq1)&minus;0.39, (eq1)&lE;14.0 and (eq2)&lE;0.8; and the total content of C and N satisfies C&plus;N&gE;0.45%.

Rolling member

A ball-and-roller bearing is disclosed having an inner ring, an outer ring arranged on the axis of the inner ring and rotating around the co-axis relative to the inner ring, and a rolling body interposed between the inner ring and the outer ring and rolling with rotation of the outer ring relative to the inner ring. One of the inner ring, the outer ring, and the rolling body has a core member made from an alloy containing iron, at least one of 0.2 to 1.0% by weight of silicon and 0.2 to 1.5% by weight of manganese, 7.0 to 11.0% by weight of chromium, 1.5 to 6.0% by weight of molybdenum, and 0.5 to 8.0% by weight of cobalt, and a case hardened surface layer. Also disclosed is the method of manufacturing the bearing by forming a core member of the alloy, forming a case hardened layer containing 0.9 to 1.5% by weight of carbon in a surface region of the core member by applying to the core member a carbonizing or carbonitriding treatment, a hardening treatment, and a tempering treatment under high temperatures, and assembling the inner ring, the outer ring and the rolling body such that the inner ring and the outer ring are positioned on the same axis and the rolling body is between the inner ring and the outer ring.

Ball-and-roller bearing and method of manufacturing the same

An inexpensive rolling apparatus improved in resistance to fretting, acoustic performance, resistance to corrosion, life and workability is provided. At least one of an outer member, an inner member and rolling elements of the apparatus is formed of an alloy steel containing 1.5% by weight or less of C, 10% to 20% by weight of Cr, 0.1% to 0.8% by weight of Mn, 0.1% to 1.0% by weight of Si and less than 0.2% by weight of N, particularly, at least one of the outer member, the inner member and the rolling elements is formed of a martensitic stainless steel containing 0.6% by weight or less of C, 10% to 14% by weight of Cr, 0.1% to 0.8% by weight of Mn, 0.1% to 1.0% by weight of Si, less than 0.2% by weight of N, 0.5% by weight or less of Mo, 0.2% by weight or less of V, and Fe and inevitable components as the balance, wherein the relationship between the content of C and that of Cr satisfies C %&lE;&minus;0.05 Cr %&plus;1.41; the relationship between a specific relational equation eq1 indicating the content of elements accelerating the conversion of the raw material to ferrite, taken as (eq1)&equals;Cr %&plus;Si %&plus;1.5 Mo %&plus;3.5 V %, and a specific relational equation eq2 indicating the content of elements accelerating the conversion of the raw material to austenite, taken as (eq2)&equals;C %&plus;0.83 N %&plus;0.12 Mn %, satisfies (eq2)&gE;0.04&times;(eq1)&minus;0.39, (eq1)&lE;14.0 and (eq2)&lE;0.8; and the total content of C and N satisfies C&plus;N&gE;0.45%.

A rolling device includes: an outer member; an inner member; and a plurality of rolling elements arranged between the outer and inner members, the outer member having a first contact surface which contacts the rolling elements, the inner member having a second contact surface which contacts the rolling elements, each of the rolling elements rolling against the first and second contact surfaces. At least one of the outer member, inner member, and rolling elements is formed of steel containing: C of less than 0.6 wt %; Cr of 10.0 wt % to 22.0 wt %; Mn of 0.1 wt % to 1.5 wt %; Si of 0.1 wt % to 2.0 wt %; N from 0.05 wt % to less than 0.2 wt %; Mo of 0 to 3.0 wt %, and V of 0 to 2.0 wt %; and the balance Fe and inevitable impurities, the steel satisfying C %+N %.gtoreq.0.45 wt %. The rolling device has excellent characteristics in fatigue strength, wear resistance, corrosion resistance, and acoustic characteristic.

Rolling bearing and rolling device

Method of manufacturing rolling bearings

An inexpensive rolling apparatus improved in resistance to fretting, acoustic performance, resistance to corrosion, life and workability is provided. At least one of an outer member, an inner member and rolling elements of the apparatus is formed of an alloy steel containing 1.5% by weight or less of C, 10% to 20% by weight of Cr, 0.1% to 0.8% by weight of Mn, 0.1% to 1.0% by weight of Si and less than 0.2% by weight of N, particularly, at least one of the outer member, the inner member and the rolling elements is formed of a martensitic stainless steel containing 0.6% by weight or less of C, 10% to 14% by weight of Cr, 0.1% to 0.8% by weight of Mn, 0.1% to 1.0% by weight of Si, less than 0.2% by weight of N, 0.5% by weight or less of Mo, 0.2% by weight or less of V, and Fe and inevitable components as the balance, wherein the relationship between the content of C and that of Cr satisfies C%.ltoreq.-0.05 Cr%+1.41; the relationship between a specific relational equation eq1 indicating the content of elements accelerating the conversion of the raw material to ferrite, taken as (eq1)=Cr%+Si%+1.5 Mo%+3.5 V%, and a specific relational equation eq2 indicating the content of elements accelerating the conversion of the raw material to austenite, taken as (eq2)=C%+0.83 N%+0.12 Mn%, satisfies (eq2).gtoreq.0.04.times.(eq1)-0.39, (eq1).ltoreq.14.0 and (eq2).ltoreq.0.8; and the total content of C and N satisfies C+N.gtoreq.0.45%.

A rolling device includes: an outer member; an inner member; and a plurality of rolling elements arranged between the outer and inner members, the outer member having a first contact surface which contacts the rolling elements, the inner member having a second contact surface which contacts the rolling elements, each of the rolling elements rolling against the first and second contact surfaces. At least one of the outer member, inner member, and rolling elements is formed of steel containing: C of less than 0.6 wt %; Cr of 10.0 wt % to 22.0 wt %; Mn of 0.1 wt % to 1.5 wt %; Si of 0.1 wt % to 2.0 wt %; N from 0.05 wt % to less than 0.2 wt %; Mo of 0 to 3.0 wt %, and V of 0 to 2.0 wt %; and the balance Fe and inevitable impurities, the steel satisfying C %+N %.gtoreq.0.45 wt % and containing retained austenite of .ltoreq.6 vol %. The rolling device has excellent characteristics in fatigue strength, wear resistance, corrosion resistance, and acoustic characteristic.

In order to provide rolling bearings of high performance using case hardened stainless steels that are superior to the conventional martensite base stainless steels in terms of corrosion resistance, rolling fatigue strength and wear resistance and which also have high core toughness, at least one member of the rolling bearing selected from among the inner race, the outer race and the rolling elements is made of an alloy steel consisting essentially of less than 0.5 wt % C, 8.0 to 20.0 wt % Cr, 0.1 to 1.5 wt % Mn, 0.1 to 2.0 wt % Si and the balance of Fe and incidental impurity elements; the relationship between the C and Cr contents satisfies 0.04 Cr (wt %)-0.39.ltoreq.C (wt %).ltoreq.-0.05 Cr (wt %)+1.41; the bearing also has a surface layer that is formed by nitriding or carbonitriding at a temperature below Ac.sub.1, subsequent heating at a temperature of 900.degree. to 1,200.degree. C., hardening, a subzero treatment and tempering.

In a rolling bearing in which at least one member of an inner race, outer race and rolling elements is made of an alloy steel containing 0.2 to 1.0 wt % of C, 3.0 to 14.0 wt % of Cr and 0.8 to 3.0 wt % of V, the balance being Fe, the member being carburized or carbonitrided, followed by hardening and tempering to secure that the surface carbon concentration C% and the concentrations Cr%+V% of Cr and V satisfy a relationship of C%.ltoreq.0.13 (Cr%+V%)+1.10 and that carbides existing on a surface of the member have an area fraction of 15 to 50%, the rolling bearing has an extending service life even if it is used under lubrication in the presence of foreign matter and exhibits superior wear resistance to be hard to wear even if there occurs a breakage of oil film.

Rolling bearing with long service life and high wear resistance

At least one of surfaces including the raceway of an inner ring, the raceway of an outer ring, and at least the rolling surfaces of rolling elements is made of a steel containing nitrogen within the range of from 0.2 to 5.0 wt. % and chromium within the range of from 7.0 to 25 wt. %.

A rolling bearing has components of an inner race, an outer race and rolling elements, one of the components being formed of an alloy steel containing 0.1-1.0 wt % of C, 0.1-1.5 wt % of Si, 0.1-1.5 wt % of Mn and 0.1-3.0 wt % of Cr, the alloy steel being carbonitrided and then ground to form a surface layer having a carbon and a nitrogen concentration of 0.6-1.5 wt % and 0.05-0.9 wt %, respectively. The surface layer has an appropriate amount of retained austenite .gamma..sub.R and is sufficiently hard to insure long life even under lubrication in the presence of foreign matter. By optimizing the choice of constituent materials, processing methods and heat treatments for each of the rolling elements and the inner and outer races, rolling bearings that have high performance can be produced at low cost.

Rolling bearings

In a rolling bearing including an inner race, an outer race and a plurality of rolling elements in which at least one member of the inner race, the outer race and the rolling elements is made of an alloy steel containing: 0.1 to 0.7 wt % of C; 0.8 to 2.0 wt % of V; 0.5 to 3.0 wt % of Cr; 0.3 to 1.2 wt % of Mn; 0.3 to 1.5 wt % of Si; at most 3.0 wt % of Mo; and the balance being Fe, the member being carburized or carbonitrided so that the member has a surface carbon concentration of 0.8 to 1.5 wt % and a surface concentration ratio V/C of 1 to 2.5 in order to cause VC-type carbides to be precipitated on a surface of the member, the rolling bearing exhibits improved wear resistance under a severe condition such as a high-temperature environment and simultaneously the rolling bearing has superior productivity.

Rolling bearing with improved wear resistance

One of component parts of an inner race, an outer race and rolling elements of a rolling bearing is composed of a bearing material that is prepared by working a high-speed steel, carburizing or carbonitriding the wrought steel in a temperature range from 800.degree. C. to less than 1200.degree. C. and subsequently hardening and tempering the carburized or carbonitrided steel, the steel composing of 0.2 wt %.ltoreq.C.ltoreq.2.3 wt %, Si.ltoreq.1.0 wt %, Mn.ltoreq.1.0 wt %, 2.0 wt %.ltoreq.Cr.ltoreq.7.0 wt %, 1.5 wt %.ltoreq.W.ltoreq.22.0 wt %, Mo.ltoreq.10.0 wt %, 0.5.ltoreq.V.ltoreq.6.0 wt %, Co.ltoreq.18.0 wt %, the balance Fe and incidental impurities. By carburizing or carbonitriding the steel at low temperatures less than 1,200.degree. C., not only high core toughness is insured but also the dissolved C or N in the surface is compensated to increase the hot strength of the steel and the compressive stress that remains in the surface after heat treatment, so that the rolling bearing that rotate at high speed and high temperatures of more 400.degree. C. extends the service life.

Rolling bearing for high-speed rotation at high temperatures

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.

Growing community of inventors

Kanagawa, Japan

Kenji Yamamura