Ntn Corporation

Hiroshi Yuki

Chikara Ohki

Kazuhiro Yagita

Michio Hori

Hideto Torisawa

Miyu Sato

In one aspect of the present invention, a method for manufacturing a bearing component includes: a preparation step of preparing a ring-shaped member of steel having a radially inner surface, a radially outer surface, and a thickness which is a distance between the radially inner surface and the radially outer surface; and a heat treatment step of performing a heat treatment to locally heat one of the radially inner surface and the radially outer surface to a heat treatment temperature and subsequently cool the one of the radially inner surface and the radially outer surface, the method satisfying S&#x2265;930/(0.3477 W&#x2212;1.594 W&#x2212;0.804), where S represents an average temperature increasing rate (unit: &#xb0; C./sec) applied when the surface is heated and W represents the thickness (unit: mm).

Bearing component and method for manufacturing the same

There is prepared a formed body constituted of steel and having an outer circumferential surface having an annular groove having a bottom surface to serve as a raceway surface of the bearing ring. In the step of forming a heated region, the formed body is induction heated to form a heated region including the bottom surface of the groove and heated to a temperature of at least an Apoint. In the cooling step, the whole of the heated region is simultaneously cooled to a temperature of not more than an Mpoint. The step of retaining the formed body in a state in which heating is stopped is performed after the step of forming a heated region before the step of cooling. In the step of retaining, dispersion in temperature in the heated region in the circumferential direction is suppressed to not more than 20&#xb0; C.

Method for producing bearing ring, double row tapered roller bearing, and method for producing double row tapered roller bearing

A double row tapered roller bearing includes: an outer ring having an annular shape; an inner ring disposed on an inner circumferential side of the outer ring and having an annular shape; and rollers. The inner ring has an outer circumferential surface facing the outer ring and having two rows of grooves having a bottom surface serving as a raceway surface. The rollers are tapered rollers disposed in the grooves in contact with the raceway surface of the inner ring and are also in contact with the outer ring. At outer circumferential surface of the inner ring, a region adjacent to the groove includes a hardened region extending from the inner peripheral surface of the groove to the region adjacent to the groove, and an unhardened region located at a position farther from the groove than the hardened region and being smaller in hardness than the hardened region.

Double row tapered roller bearing, bearing ring, and method for producing double row tapered roller bearing

A method for producing a bearing ring of a rolling bearing includes the steps of: preparing a formed body constituted of hypereutectoid steel; forming an annular heated region heated to a temperature of at least an Apoint on the formed body by relatively rotating an induction heating member arranged to face part of an annular region for becoming a rolling contact surface of the bearing ring in the formed body to induction-heat the formed body along the circumferential direction of the annular region; and simultaneously cooling the whole of the heated region to a temperature of not more than an Mpoint.

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Kuwana, Japan

Hiroshi Yuki