Abstract: An ultrasonic flaw detection method for detecting a flaw which inspects a raceway surface 4a of an outer ring 4 as a surface to be inspected. After the surface to be inspected has finished undergoing finish grinding, a flaw is ultrasonically detected while liquid hydrocarbon 2 including kerosene is taken as an ultrasonic wave transmission medium.

Abstract: A first object is to provide a method for evaluating large-sized inclusions in a bearing steel. The method enables quantitative evaluation of large-sized inclusions even if the steel has a high degree of cleanliness. Further, a second object is to provide an appropriate bearing steel evaluated by the method for evaluating large-sized inclusions. Further, a third object is to provide a rolling bearing capable of eliminating short life products and cracked products and providing longer lifetime for entire bearings. In order to achieve the first object, a round bar formed of a bearing steel to be evaluated and an ultrasonic probe are placed in an ultrasonic transmission medium, and the size and number of large-sized inclusions that are present in the flaw detection volume are measured to estimate the existence probability of large-sized inclusions in the bearing steel to be evaluated.

Abstract: An inner ring 1 and an outer ring 2 are assured by a non-destructive inspection that the maximum length of a non-metallic inclusion existing in an area between the raceway surface and a depth twice a depth Z0 where the maximum shearing stress exerts is 0.

Abstract: The present invention provides a rolling bearing having high wear resistance at high temperature and with reduced manufacturing cost. At least one of an inner ring, an outer ring and rolling elements is formed of the following steel material into a predetermined shape, then applied with hardening and tempering at a temperature of 240° C. or higher or 350° C. or lower to make the Vickers hardness (Hv) on the raceway surface and/or rolling surface to 720 or more. The steel material contains, as the alloy ingredient, 0.8% by weight or more and 1.2% by weight or less of C, 0.5% by weight or more and 2.5% by weight or less of Si, 0.7% by weight or more and 1.5% by weight or less of Cr, 0.8% by weight or more and 2.0% by weight or less of Mo and 0.3% by weight or more and 1.2% by weight or less of Mn, with a ratio of Mo to Cr (Mo/Cr: weight ratio) of 1.1 or more.

Abstract: A surface to serve as a surface under ultrasonic inspection has a roughness of 0.4 &mgr;mRa or less, and wherein all imperfections existing a controlled volume X corresponding to all cross sections of a raceway ring 1 assume a length of 0.2 mm or less as represented by the square root of areas of the imperfections. Accordingly, it is possible to provide a rolling bearing which does not become short-lived and obviates a concern about occurrence of cracking even when used in a harsh environment.

Abstract: The continuous annealing furnace has two or more treatment chambers sequentially connected with each other and respectively filled with a gas atmosphere differing in carburizing property, which includes a carburizing chamber wherein roller members to be treated are carburized at 750° C. to 820° C., a slow cooling chamber wherein the roller members are cooled at said temperature or less of the carburizing chamber, an intermediate chamber including atmosphere gas blocking doors that can open/close an exit of the carburizing chamber and an entrance of the slow cooling chamber independently, and transferring means, and each chambers is filled to satisfy a relationship of K1−K2≧2 where K1 represents a partial pressure ratio between CO and CO2 in an atmosphere within the carburizing chamber and K2 represents a partial pressure ratio between CO and CO2 in an atmosphere within the slow cooling chamber.

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 &mgr;m. Cr-equivalent amount (%)=[Cr]+2[Si]+1.5[Mo]+5[V]+5.5[Al]+1.75[Nb]+1.5[Ti]  (1).

Abstract: There is disclosed a sliding rotation member which is rotatably supported by a support shaft in a toroidal continuously variable transmission, and slides on another member, wherein a maximum shear stress depth generated at a maximum deceleration time of the toroidal continuously variable transmission is defined as Z0, a size of a defect obtained in accordance with a shape of the defect detected by a nondestructive inspection method is defined as a square root length, and then a defect of 0.05 mm or more in terms of the square root length is not included in a range of a depth from the surface which is twice the depth Z0.

Abstract: An outer ring 2 as a stationary ring is fabricated with a steel material having the composition as shown under. The steel material contains, as alloying elements, C 0.80 to 1.10 wt %, Si 0.20 to 0.50 wt %, Mn 0.2 to 1.0 wt %. It also contains any two kinds or more of Cr, Mo and V at rates of Cr: 1.2 to 3.5 wt %, Mo: 0.5 to 1.5 wt % and V: 0.2 to 1.0 wt %. The containing rates of Cr, Mo and V satisfy the under mentioned formula (1). It further contains Ti and/or Cu at rates of Ti: 0.05 to 0.20 wt % and Cu: 0.2 to 2.0 wt % 1.8≦[Cr]×0.6+[Mo]×0.5+[V]≦3.0  (1). Accordingly, it is possible to remarkably lengthen the life of a rolling bearing such as a bearing for alternator to be used under high vibration and high load.

Abstract: A surface to serve as a surface under ultrasonic inspection has a roughness of 0.4 &mgr;mRa or less, and wherein all imperfections existing a controlled volume X corresponding to all cross sections of a raceway ring 1 assume a length of 0.2 mm or less as represented by the square root of areas of the imperfections. Accordingly, it is possible to provide a rolling bearing which does not become short-lived and obviates a concern about occurrence of cracking even when used in a harsh environment.

Abstract: A rolling bearing contains no more than 0.3 wt % of nitrogen in a grinding allowance portion after carbonitriding and hardening heat treatments, contains from 0.9 wt % (inclusive) up to 1.6 wt % (inclusive) of carbon and from 0.05 wt % (inclusive) up to 0.3 wt % (inclusive) of nitrogen in the surface layer of the finished part and has a nitrogen gradient of no more than 0.5 wt %/mm in the surface layer of the finished part. The rolling bearings are improved in grinding efficiency and which have their rolling life extended significantly.

Abstract: In view of the fact that, when backup roll bearings which have been found satisfactory in the purity thereof in the sample evaluation through observations using a microscope are checked many times for the top surface layer portions of the raceway surfaces thereof according to an ultrasonic detecting method, on quite rare occasions, there can be found a bearing which contains one or more inclusions each having a size of as large as several hundreds &mgr;m, and such inclusions give rise to occurrence of a short-life bearing as a finished product, a range expressed by 2% Da depth×raceway surface is used as a test piece volume and the size of a non-metallic inclusion existing in the test piece volume is restricted to a length less than 500 &mgr;m, preferably, less than 100 &mgr;m. Here, the term “2% Da depth” means a depth up to 2% of a rolling element mean diameter from the surface of an inner or outer race of a bearing.

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 &mgr;m.

Abstract: An outer ring 2 as a stationary ring is fabricated with a steel material having the composition as shown under. The steel material contains, as alloying elements, C 0.80 to 1.10 wt %, Si 0.20 to 0.50 wt %, Mn 0.2 to 1.0 wt %. It also contains any two kinds or more of Cr, Mo and V at rates of Cr: 1.2 to 3.5 wt %, Mo: 0.5 to 1.5 wt % and V: 0.2 to 1.0 wt %. The containing rates of Cr, Mo and V satisfy the under mentioned formula (1). It further contains Ti and/or Cu at rates of Ti: 0.05 to 0.20 wt % and Cu: 0.2 to 2.

Abstract: In view of the fact that, when backup roll bearings which have been found satisfactory in the purity thereof in the sample evaluation through observations using a microscope are checked many times for the top surface layer portions of the raceway surfaces thereof according to an ultrasonic detecting method, on quite rare occasions, there can be found a bearing which contains one or more inclusions each having a size of as large as several hundreds &mgr;m, and such inclusions give rise to occurrence of a short-life bearing as a finished product, a range expressed by 2% Da depth×raceway surface is used as a test piece volume and the size of a non-metallic inclusion existing in the test piece volume is restricted to a length less than 500 &mgr;m, preferably, less than 100 &mgr;m. Here, the term “2% Da depth” means a depth up to 2% of a rolling element mean diameter from the surface of an inner or outer race of a bearing.

Abstract: In view of the fact that, when backup roll bearings which have been found satisfactory in the purity thereof in the sample evaluation through observations using a microscope are checked many times for the top surface layer portions of the raceway surfaces thereof according to an ultrasonic detecting method, on quite rare occasions, there can be found a bearing which contains one or more inclusions each having a size of as large as several hundreds &mgr; m, and such inclusions give rise to occurrence of a short-life bearing as a finished product, a range expressed by 2%Da depth×raceway surface is used as a test piece volume and the size of a non-metallic inclusion existing in the test piece volume is restricted to a length less than 500 &mgr;m, preferably, less than 100 &mgr;m. Here, the term “2%Da depth” means a depth up to 2% of a rolling element mean diameter from the surface of an inner or outer race of a bearing.

Abstract: In manufacturing a rolling bearing, at least one component of an inner ring, an outer ring, and a rolling element is manufactured from an alloy steel comprising 0.05 weight %-0.5 weight % carbon, 0.5 weight %-18 weight % chromium, 1.5 weight % or less silicon, 5 weight % or less molybdenum, 4.0 weight % or less vanadium, 4 weight % or less nickel, and 8 weight % or less tungsten, by subjecting the alloy steel to carburizing, hardening and tempering. The carburizing is carried out by vacuum carburization. In the vacuum carburization, carburizing and diffusion are carried out by introducing an acetylene-based carburizing gas in a hot atmosphere under reduced pressure, followed by hardening and tempering. The use of the vacuum carburization enables carburization with the chromium (Cr) content being 3.0 weight % or more, and even up to 18 weight %, which was difficult to achieve with the conventional gas carburization (pre-oxidation+gas carburizing).

Abstract: At least one of the components of a rolling member used in a manner in which it is rolled or slid with a mated member is made of carbon steel containing 0.8%-0.9% by weight of C, 0.1%-0.7% by weight of Si, 0.5%-1.1% by weight of Mn, and 0.1%-0.6% by weight of Cr and Fe substantially in the remaining part, wherein an ideal critical diameter DI value calculated from the compositions is 1.5-4.0, and the retained austenite amount after hardened heat treatment is 8%-22% by volume. The value DI is determined by the following equation:DI=(0.311.times.C %.sup.0.498).times.(0.7.times.Si %+1).times.(3.33.times.Mn %+1).times.(2.16.times.

Abstract: In an ultrasonic detecting method for a bearing ring in which a bearing ring 2 and an ultrasonic detection probe 3 are disposed within ultrasonic transmission medium such as water, then ultrasonic wave is transmitted from the ultrasonic detection probe 3 to the bearing ring 2, and a defect of the bearing ring 2 is detected on the basis of an ultrasonic wave echo reflected from the bearing ring 2, wherein at least a defect in a range from the surface of the bearing ring 2 to a position beneath by 2 mm from the surface of the bearing ring which is deeper than a maximum shearing stress position of the bearing ring 2 is detected by an angle beam method with an incident angle in a range of 10 to 30.degree., preferably in a range of 25 to 30.degree., and a defect in a range deeper than the range detected by the angle beam method is detected by a normal beam method with an incident angle in a range of 0 to 10.degree., preferably in a range of 0 to 5.degree.

Abstract: A rolling bearing includes a rolling element made of a steel containing 0.9 to 1.1 wt. % C, 0.1 to 0.5 wt. % Si, 0.2 to 0.8 wt. % Mn, 1.0 to 1.8 wt. % Cr, with the balance being Fe and inevitable impurities. In the rolling bearing at least the surface of the rolling element includes carbides having an area fraction of 5% to 15%; of these carbides, carbides having an averaged particle diameter of 0.5 .mu.m or more share 50% or more of the area fraction of all the carbides; and of the carbides, carbides having an averaged particle diameter of 1 .mu.m or more share 2% or less of the area fraction of all the carbides; and wherein the rolling element has at least a Vickers surface hardness HV of 750 to 900.