Shaft member for fluid bearing device, manufacturing method therefor, and fluid bearing device
AssigneeNtn Corporation
InventorsJun Hirade, Masashi Yamagou, Mikihisa Fujiwara, Tetsuya Kurimura
Life of this patent
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Abstract
A shaft member for a fluid bearing device includes, on an outer peripheral surface thereof, two bearing surfaces (31 and 32) separated from each other in an axial direction, and a middle relief portion (33) formed between the bearing surfaces (31 and 32) and having a diameter smaller than a diameter of the bearing surfaces. The middle relief portion (33) includes a cylindrical surface portion (331) having a ground surface, and stepped portions (332) arranged on both axial sides of the cylindrical surface portion and having a diameter difference from the cylindrical surface portion.
Claims19
A shaft member for a fluid bearing device, the shaft member comprising:
- two bearing surfaces separated from each other in an axial direction;
- and
- a middle relief portion formed between the two bearing surfaces and having a diameter smaller than a diameter of the two bearing surfaces,
- the two bearing surfaces and the middle relief portion being formed on an outer peripheral surface of the shaft member,
- wherein the middle relief portion includes:
- a ground cylindrical surface portion;
- and
- stepped portions arranged on both axial sides of the ground cylindrical surface portion and having a diameter difference from the ground cylindrical surface portion.
A manufacturing method for a shaft member for a fluid bearing device, the shaft member including two bearing surfaces separated from each other in an axial direction, and a middle relief portion formed between the two bearing surfaces and having a diameter smaller than a diameter of both the bearing surfaces, the manufacturing method comprising:
- forming the middle relief portion and the bearing surfaces by turning on a metal material;
- and
- after the forming, simultaneously grinding the middle relief portion and the bearing surfaces while only the middle relief portion is supported by a shoe.
A manufacturing method for a shaft member for a fluid bearing device, the shaft member including two bearing surfaces separated from each other in an axial direction, and a middle relief portion formed between the two bearing surfaces and having a diameter smaller than a diameter of both the bearing surfaces, the manufacturing method comprising:
- forging a metal material;
- and
- after the forging, grinding the middle relief portion and the bearing surfaces and further simultaneously grinding the middle relief portion and the bearing surfaces while only the middle relief portion is supported by a shoe.
Dependencies are inferred from the claim text.