Nsk Corporation

Kyushu University

Shinji Fujita

Yasuo Murakami

Nobuaki Mitamura

Shigeru Okita

Susumu Tanaka

Youichi Matsumoto

Yukitaka Murakami

Hideyuki Uyama

Koichi Hachiya

Tomoharu Saito

Takanori Tanaka

Hiroyuki Uchida

Masato Kobayashi

Daiju Takahashi

In forming an actuator, a large end surface of a tapered roller of a tapered roller bearing is shot with minute particles of silicon carbide having a diameter of 0.5 to 100 &#x3bc;m and having an angle formed by crushing, and such a surface is scraped concavely at a diameter within a range from 0.5 to 100 &#x3bc;m to form a large number of concavities having a depth of equal to or greater than 1 &#x3bc;m at a pitch of equal to or less than 200 &#x3bc;m. The concavities are non-continuous and isolated from each other, and serve as a lubricant puddle. The concavities are formed by scraping and not by plastic deformation, and thus the surface is not hardened.

Method for producing an actuator

An inclusion rating method includes carrying out a tensile test on a test specimen, which is made of a metallic material and charged with a hydrogen, to cause a fracture originating from a nonmetallic inclusion affected by the hydrogen in the test specimen, identifying a type of the nonmetallic inclusion, measuring a size of the nonmetallic inclusion, and evaluating a cleanliness of the metallic material by obtaining a distribution function of the size of the nonmetallic inclusion.

Inclusion rating method

A rolling bearing comprises an outer ring, an inner ring and rolling elements rotatably disposed between the outer and inner rings. At least a member selected from the outer ring, inner ring and rolling elements has C content of 0.2 or more and 0.6 or less wt %, Cr content of 2.5 or more and 7.0 or less wt %, Mn content of 0.5 or more and 2.0 or less wt %, Si content of 0.1 wt % or more and 1.5 or less wt %, and Mo content of 0.5 or more and 3.0 or less wt %. Further, a carburizing or carbo-nitriding treatment, a quenching treatment and a tempering treatment are applied to the selected member. Furthermore, retained austenite on a surface thereof is 15% or more and 45% or less vol. %, and the surface hardness thereof is HRC60 or more.

Rolling bearing

A rolling device in which damage such as seizure or wear is less liable to occur and which has a long life, even when used under severe conditions such as high speed, heavy load, high temperature and insufficient lubrication. A thrust needle roller bearing includes an inner ring, outer ring, and a plurality of rolling elementsrollably arranged between a raceway surfaceof inner ringand a raceway surfaceof outer ring. A lubricant film consisting of a solid lubricant is coated over an area equivalent to an area ratio of 75% or more of at least one member of the group consisting of raceway surfaceof inner ring, raceway surfaceof outer ring, and a rolling contact surfaceof rolling element. The thickness of the lubricant film is preferably 0.05 &#x3bc;m or more and 8 &#x3bc;m or less.

Rolling device

A rolling bearing intended for longer life by improving seizure resistance and wear resistance in the circumstance with slip contact or in the circumstance where lubricant tends to be exhausted, which is manufactured by applying carburization or carbonitridation to an Si-added material to disperse and precipitate carbides or carbonitrides containing Si or Si&#x2014;X (X=one or more of Mn, Mo, and Cr) thereby improving the seizure resistance and the wear resistance by the self-lubrication effect thereof, the size of the carbides or carbonitrides being preferably 10 &#x3bc;m or less for preventing flaking, and the area ratio for the carbides or carbonitrides being preferably 1.0&#x2013;30% for obtaining sufficient self-lubrication effect.

A rolling bearing has the radius of curvature of the raceway on an inner ring and an outer ring is from not smaller than 50.1% to not greater than 51.9% of the diameter of the balls, and at least one of the compositions of the bearing is obtained by forming an alloy steel having a carbon (C) content of from not smaller than 0.50% to not greater than 0.90%, a chromium (Cr) content of from not smaller than 3.0% to not greater than 15.0%, a manganese (Mn) content of from not smaller than 0.10% to not greater than 2.0%, a silicon (Si) content of from not smaller than 0.10% to not greater than 2.0%, a molybdenum (Mo) content of zero or not greater than 2.0% by weight, and a vanadium (V) content of zero or not greater than 2.0%, by weight.

Growing community of inventors

Fujisawa, Japan

Shinji Fujita