Ntn Corporation

Yukio Matsubara

Noriaki Miwa

Chikara Ohki

Daisuke Sato

Kikuo Maeda

Tomoya Sakaguchi

Hiroo Morimoto

Hitoshi Ishii

Takakazu Kitagawa

Masayuki Kawakita

Hisamitsu Maeda

Noriaki Sakanaka

Hiromasa Tanaka

Provided is a rolling device in which hydrogen is not easily accumulated within a roller element made of steel, such as an inner race and an outer race, and premature separation due to hydrogen embrittlement is prevented from occurring. A rolling bearinghaving an inner race, an outer race, and rolling bodies, and at least one selected from the inner race, the outer race, and the rolling bodiesis made of predetermined steel. At least a part of oxide-based inclusions included in the steel is covered by MnS, and a ratio of a number of oxide-based inclusions covered by MnS is over 40% of a total number of oxide-based inclusions having maximum diameter of 3 &#x3bc;m or greater in the steel.

Rolling device

A bearing component composed of steel which contains carbon not less than 0.95 mass % and not more than 1.1 mass %, silicon less than 0.3 mass %, manganese less than 0.5 mass %, sulfur less than 0.008 mass %, and chromium not less than 1.4 mass % and less than 1.6 mass % and is composed of remainder iron and an impurity and having a carbonitrided layer formed at a surface portion including a contact surface which is a surface in contact with other components is provided. An average concentration of nitrogen in the surface portion is not lower than 0.3 mass % and not higher than 0.6 mass % and variation in nitrogen concentration in the surface portion is not higher than 0.1 mass %. An amount of retained austenite in the surface portion is not greater than 8 volume %.

Bearing component and rolling bearing

A bearing component composed of steel which contains carbon not less than 0.95 mass % and not more than 1.1 mass %, silicon less than 0.3 mass %, manganese less than 0.5 mass %, sulfur less than 0.008 mass %, and chromium not less than 1.4 mass % and less than 1.6 mass % and is composed of remainder iron and an impurity and having a carbonitrided layer formed at a surface portion is provided. An average concentration of nitrogen in the surface portion is not lower than 0.3 mass % and not higher than 0.6 mass % and variation in nitrogen concentration is not higher than 0.1 mass %. An amount of retained austenite is not greater than 8 volume %. An area ratio of a precipitate in the inside where no carbonitrided layer is formed is not lower than 11%.

A status monitoring system for accurately determining the contaminant water concentration in a lubricant oil used in a rolling device includes a contaminant water concentration monitoring device configured to monitor the contaminant water concentration in the lubricant oil. The contaminant water concentration monitoring device includes an electrostatic capacitance detector and an oil temperature measuring instrument, which are configured to detect the electrostatic capacitance and the oil temperature of the lubricant oil, respectively, and a water concentration calculation section configured to calculate the contaminant water concentration from the detected electrostatic capacitance and oil temperature in accordance with a predetermined rule.

Status monitoring system and status monitoring method for rolling device

A method of assessing the shear fatigue property of a metallic material that undergoes a rolling contact includes a testing step for determining the relation between the shear stress amplitude of a rolling contact metallic material and the number of loading by means of an ultrasonic torsional fatigue test, and a shear fatigue strength determining step for determining the shear fatigue strength &#x3c4;lim within the ultra long life regime from the relation between the shear stress amplitude and the number of loadings, which relation has been determined during the test step, in accordance with a predetermined standard. It is a completely reversed torsional fatigue test, in which torsional vibrations, respective torsions in the positive rotational direction and reversed rotational direction of which are symmetrical relative to each other, are applied to a test piece.

Assessment of shear fatigue property of rolling contact metal material and estimation of fatigue limit maximum contact pressure using same assessment

A power transmission shaft mitigates the concentration of both tensile stress and shear stress to achieve an improvement in terms of fatigue strength. A male spline section is formed on an outer periphery of the power transmission shaft. On a valley section of the male spline section, at an axially opposite end side portion thereof, there is provided a diameter-expanded section whose outer diameter dimension is gradually increased toward an axially opposite end. Rounded sections having a circular arc cross-section are provided on both circumferential sides of the diameter-expanded section. A radius of curvature of the rounded sections is gradually increased toward the axially opposite end.

Power transmission spline

There is provided a rolling component formed of a steel material of the medium carbon steel level that provides a rolling life improved to be comparable to that of bearing steel and also provides improved characteristic against surface-cracking, and a power transmission component including the rolling component. To achieve this, the rolling component is formed of steel having an induction hardened portion having a stress intensity factor range associated with tension associated-fatigue crack extension that has a lower limit &#x394;Kth of 6.2 Mpa&#x221a;m.

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Kuwana, Japan

Yukio Matsubara