Nsk Corporation

Kabushiki Kaisha Toshiba

Nippon Seiko Kabushiki Kaisha

Other

Shigeru Okita

Akihiro Kiuchi

Susumu Tanaka

Yasuo Murakami

Nobuaki Mitamura

Hiromichi Takemura

Manabu Ohori

Tomonobu Yoshikawa

Kazuo Sekino

Shinichi Shirota

Takashi Seki

Kyozaburo Furumura

Noboru Taga

Kenji Yamamura

Daisuke Maruyama

Tsutomu Abe

Hiroyuki Ito

Koji Ueda

Tatsuya Ishikawa

Satoshi Kadokawa

Tsutomu Ohkubo

Toyohisa Yamamoto

Kiyoshi Hirakawa

Youichi Matsumoto

Hiroshi Narai

Yasumi Watanabe

Hideyuki Uyama

Shinji Fujita

Junji Minakuchi

Masato Kato

Yasuo Utsumi

Yuuji Miyamoto

Akira Iida

Kazuhiro Fujiu

Munetaka Mitsumura

Toichi Kondo

Kazuo Hayakawa

Shizuo Mitsuhashi

Akira Uchida

Yutaka Ishii

There is provided an aluminum die cast part strength evaluating method is provided for correctly evaluating strength of an actual aluminum die cast part. Strength of the actual aluminum die cast part will be correctly evaluated by conducting ultrasonic inspection of a predetermined range of a high stress region of an aluminum die cast part, which is found out through stress analysis beforehand, for an internal defect, and evaluating that the aluminum die cast part has a predetermined strength if the maximum internal defect area within the predetermined range is equal to or less than a predetermined value. Moreover, an actual aluminum die cast part with a predetermined strength will be evaluated correctly by: evaluating strength using the aluminum die cast part strength evaluating method and setting the maximum-possible internal defect area within the predetermined range of the high stress region to 0.8 mmor less.

Strength evaluating method for aluminum die cast part, aluminum die cast part, and defect detecting method for the same

The invention provides a ball screw apparatus which suppresses abrasion and damage by competition of balls, controls spaces between retaining pieces and balls, and prevents retaining pieces from falling, thereby enabling to more improve operating ability. The retaining pieces are positioned between the balls running in a ball rolling path, such that a sum total of the spaces between the retaining pieces and the balls is 50% or less of an outer diameter size of the retaining piece, and at the same time a contact angle between the retaining piece and the ball is 25&#xb0; or above to 40&#xb0; or below.

Ball screw apparatus

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.

Rolling bearing

A ball screw has a screw shaft including a spiral-shaped ball rolling groove formed in an outer peripheral surface thereof; a nut including a spiral-shaped ball rolling groove formed in an inner peripheral surface thereof; a plurality of balls disposed in a raceway formed by the two rolling grooves; and, a return path for moving the balls from the terminal point of the raceway to the start point of the raceway, the two end portions of the return path respectively including a rising surface rising from the ball rolling groove of the nut and a stopper portion disposed opposed to the rising surface to form the end portion of the raceway, wherein a boundary portion between the rising surface and the ball rolling groove of the nut is formed a round portion having the radius of curvature 0.05 times the diameter of the ball or more.

Ball screw

In a wheel-support rolling bearing unit, in order to made a flangethinner and thus lighten the bearing unit without impairing fatigue strength, machinability, and workability after forging, the composition of the alloy steel constituting the flange attached member (hub ring), the surface hardness of the root portionon the axial outside surface side of the flange, and the surface roughness, are stipulated to thereby improve the durability ratio (fatigue limit strength/tensile strength) of the flange. In one aspect, the member is made from an alloy steel containing C: 0.5 to 0.65 weight %, Mn: 0.3 to 1.5 weight %, Si: 0.1 to 1.0 weight %, Cr: 0.01 to 0.5 weight %, S: 0.35 weight % or less, and any one type or more selected from 0.01 to 0.2 weight % of V, 0.01 to 0.15 weight % of Nb, and 0.01 to 0.15 weight % of Ti, with the rest being Fe and inevitable impurities, and the oxygen contents is 15 ppm or less. Moreover, the surface hardness of the inner racewayformed with the hardened layer, is between Hv 650 and 780, and the surface hardness of a portion not formed with the hardened layer is between Hv 230 and 300.

Wheel-support rolling bearing unit

A ball screw apparatus which can suppress retaining pieces from contacting a wall of a ball rolling path or ball circulating path, and suppress the retaining pieces between the balls from falling down, so that such a ball screw apparatus can be improved in noise reduction, operability and endurance. The retaining piece is rounded at an edge portion opposite to the ball, such that a radius of curvature of the edge portion is defined to be 0.05 mm to 1 mm, and the outer diameter of the retaining piece is in a range of 0.60 times or more to 0.85 times or less of the diameter of the ball.

A full complement angular ball bearing with no cage and having a contact angle from 10 to 45&#xb0; and an increased number of balls for use under severe conditions. The life is extended by defining the surface roughness of the inner ring and the outer ring, defining the roughness ratio of them relative to the rolling element, defining the Cr content in the alloy steel for the rolling element, forming the rolling element with oxide ceramics, or providing a dense nitride layer on the surface of the rolling element, avoiding the presence of particles with a mean diameter in excess of 3 &#x3bc;m on the raceway surfaces of the outer ring and the inner ring, or coating a film of a hardness higher than that of the raceway surface of the outer ring and the inner ring on the surface of the rolling element.

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&deg; C. or higher or 350&deg; 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.

A toroidal continuously variable transmission system of the present invention is provided with an input disk, an output disk and power rollers. The input and output disks have traction surfaces defined between a small-diameter portion and a large-diameter portion and having an arc-shaped concave section. The input and output disks are coaxially arranged in such a manner that the traction surfaces face each other. The power roller are frictionally engagement with the traction surfaces of the input and output disks and transmit a driving force. At least one of the input disk, the output disk and the power rollers is formed of an alloy steel which contains 0.15 to 2.0% by weight of Mo. The alloy steel is subjected first to carburization or carbonitriding processing executed at a temperature not lower than 1,000&deg; C., and then to hardening and tempering. The alloy steel has a surface carbon content of 0.8 to 1.4%.

Toroidal continuously variable transmission and manufacturing method thereof

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&deg; C. to 820&deg; 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 K &minus;K &gE;2 where K represents a partial pressure ratio between CO and CO in an atmosphere within the carburizing chamber and K represents a partial pressure ratio between CO and CO in an atmosphere within the slow cooling chamber.

Method of manufacturing inner and outer races of deep groove ball bearing in continuous annealing furnace

In a rolling bearing having a fixed race, a rotary race and a plurality of rolling elements disposed between said fixed race and said rotary race, at least said fixed race is made of a steel having 0.35 to 0.55% by weight of C, 11.0 to 17.0% by weight of Cr, 0.05 to less than 0.2% by weight of N and the rest of Fe and unavoidable components. Further, the sum of the content of C and N is from 0.45 to 0.65% by weight or less, and exhibits a surface hardness HRC of 57 or more after heat treatment and the diameter of eutectic carbide produced on said bearing races is 10 &mgr;m or less.

As a steel material for an inner race, an outer race and a rolling element constituting a rolling bearing, there is used one containing carbon (C) and chromium (Cr) in an amount of 0.65 wt % to 1.10 wt % and 2.0 wt % to 6.0 wt %, respectively. At least one of the inner race, the outer race and the rolling element is formed from the steel material. The inner race, outer race and the rolling element thus formed is then subjected to hardening, tempering and polishing. Further, a chromium oxide layer (Cr O ) having a thickness of 5 nm to 300 nm is formed on a race track surface of at least one of the inner race, the outer race and the rolling element. If the rolling bearing is used in operation under the lubrication at a high traction coefficient with water mixed therein, finely particulate molybdenum carbide and/or vanadium carbide having a particle diameter of 50 nm to 300 nm is distributed in the matrix.

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.

Rolling bearing and heat treatment method therefor

Growing community of inventors

Yokohama, Japan

Shigeru Okita