Ntn Corporation

Masatoshi Niina

Shinji Oishi

Kousuke Obayashi

Kazuyoshi Harimoto

Masahiko Satoda

Yukimitsu Yamamoto

Ayumu Yamamoto

Seiji Takahashi

A shell type outer ringof a shell type needle roller bearingis formed by a pressing combined with an ironing step, and the lubricating conditions in this ironing step on the outer-diameter ironed surface, which becomes the outer-diameter surface of the outer ring, are in a substantially fluid lubricating state so as to restrict the circumferential surface roughness of the inner-diameter surface, the inner-diameter roundness, and the amount of uneven thickness of the tubular portion to predetermined value ranges, thereby prolonging the life of the shell type needle roller bearing and lowering the acoustic level during use.

Method of manufacturing a shell type needle roller bearing including drawing and ironing operations

A rocking bearing is proposed which is low in cost. A raceway is formed on the inner periphery of an arcuate bearing ring. Rolling elements are received in pockets of a retainer provided opposite to the raceway. The bearing ring is formed by pressing a steel plate to reduce the cost and achieve light weight and compactness.

Rocking bearing

In a thrust ball bearing, the heat treating hardness and heat treatment hardening depth of a bearing ring 4a (4b) are prescribed such that, at any depth from the raceway surface 4a1 (4b1), the value which is seven times the dynamic shearing stress .tau..sub.ZY produced at a certain depth from the raceway surface 4a1 (4b1) by the rolling movement of the rolling element 4c does not exceed the hardness at that depth. More particularly, with Vickers hardness Hv=520 adopted as a reference hardness, heat treatment (for example, carburizing) is effected such that a hardened layer with Hv=520 is present at a depth not less than 4% of the diameter d of the balls 4c.

Thrust ball bearing

The inner circumference 4a2 of the bearing ring 4a is square-shaped, and the outer circumference 4a3 thereof is circular. The shoulder 1a1 of the attaching portion 1a of the scroll member 1 is formed to be square-shaped, corresponding to the inner circumference 4a2 of the bearing ring 4a. When attaching the bearing ring 4a to the attaching portion 1a, the square-shaped inner circumference 4a2 of the bearing ring 4a is fitted to the square-shaped shoulder 1a1 of the attaching portion 1a. Thus, by fitting the inner circumference 4a2 of the bearing ring 4a to the shoulder 1a1 of the attaching portion 1a, the bearing ring 4a is prevented from rotating with respect to the swivel scroll member 1.

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Iwata, Japan

Masatoshi Niina