Ntn Corporation

Mineo Koyama

Masatsugu Mori

Mamoru Mizutani

Hiroshi Takiuchi

Hideto Torisawa

Takahiro Kanamoto

Wakana Inoue

Keisuke Nasu

A ball bearing retainer holds balls disposed between an inner ring and an outer ring, in pockets formed at a plurality of portions, in a circumferential direction, of an annular body. The annular body includes: annular parts disposed on both sides in an axial direction; and pillar parts that are disposed at a plurality of portions in the circumferential direction and that connect between the annular parts. The pockets are formed by the annular parts and the pillar parts adjacent to each other in the circumferential direction, and allow ball guide. First contact portions of the pillar portions, which contact portions contact with the balls in the circumferential direction, are formed by first planes that extend along the axial direction, and the balls are guided by the first planes.

Ball bearing cage

An object is to provide a motor-incorporation-spindle ball bearing capable of allowing cooling air which enters inside the bearing of the motor-incorporation-spindle to be discharged smoothly out of the bearing without causing turbulent flow inside the bearing, does not cause a retainer easily to be vibrated, and provides a high level of silent operation. A seal plate has a length to allow air to pass through the bearing from an entrance side toward an exit side substantially straightly without resistance. Therefore, the seal plate is less likely to be exposed to unnecessary force when the air passes through the bearing; the seal plate is prevented from wobble and deformation; stable sealing is ensured; the air is discharged smoothly without causing turbulent flow inside the bearing; a retainer is not easily vibrated, and silent operation is maintained.

Ball bearing for spindle with built-in motor

Let r be the radius of curvature of the corners of pockets of a cage, and Lw be the length of cylindrical rollers. They are set such that the relation r/Lw&#x2267;0.1 holds. Further, the relation r/k&#x2266;1 holds, where kis the minimum dimension on the inner diameter side of the annulus of the cage.

Cylindrical roller bearing and cage for cylindrical roller bearings

Contact surface pressure P increases rather drastically in proportion to skew angle &#x3b8; within the range of 0&#x3c;&#x3b8;&#x2266;&#x3b8;, but because the critical skew &#x3b8;is restricted to be small, the contact surface pressure P changes in a low range below a certain level Pat which wear occurs in contact portions. Thus restricting the critical skew angle &#x3b8;to a small angle reduces the contact surface pressure P and suppresses heat generation and wear in the contact portions.

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Kuwana, Japan

Mineo Koyama