Sintered gear

Patent metadata

Field	Value
Publication number	US-11745261-B2
Application number	US-201917638200-A
Country	US
Kind code	B2
Filing date	Aug 30, 2019
Priority date	Aug 30, 2019
Publication date	Sep 5, 2023
Grant date	Sep 5, 2023

Abstract

A sintered gear of annular shape which has a composition including a metal, has a plurality of pores in a surface thereof, and has a relative density of 93% or more and 99.5% or less.

First claim

The invention claimed is:

1. A sintered gear of annular shape, the sintered gear having a composition including a metal, wherein
the sintered gear has a plurality of pores in a surface thereof,
the sintered gear has a relative density of 93% or more and 99.5% or less,
the sintered gear has a periodic concave and convex shape for containing a lubricant at a tooth bottom thereof, and
a periodicity of the concave and convex shape has a length of 1 mm or more.

2. The sintered gear according to claim 1 , wherein the metal is an iron-based alloy.

3. The sintered gear according to claim 1 , wherein the sintered gear has, at a tooth root thereof, a portion recessed from a tooth surface inwardly in a tooth thickness direction.

4. The sintered gear according to claim 1 , wherein the sintered gear has a lathe mark on an outer circumferential surface of a tooth tip thereof.

5. The sintered gear according to claim 1 , wherein the sintered gear has a lathe mark on at least one of two end surfaces located at axial ends of the sintered gear.

6. The sintered gear according to claim 2 , wherein the iron-based alloy includes one or more elements selected from the group consisting of C, Ni, Mo, Mn, and B.

7. The sintered gear according to claim 1 , wherein an average sectional area of the pores in any cross section of the sintered gear is 500 μm 2 or less.

8. The sintered gear according to claim 1 , wherein an average circumferential length of the pores in any cross section of the sintered gear is 100 μm or less.

9. The sintered gear according to claim 1 , wherein an average value of maximum diameters of the pores in any cross section of the sintered gear is 5 μm or more and 30 μm or less.

10. The sintered gear according to claim 1 , wherein a maximum value of a maximum diameter of the pore in any cross section of the sintered gear is 30 μm or less.

11. A method of manufacturing a sintered gear, the method comprising:
a first step of compressing a raw powder to produce a pressed powder body having a relative density of 93% or more and 99.5% or less;
a second step of subjecting the pressed powder body to cutting which includes gear cutting; and
a third step of sintering the pressed powder body subjected to the cutting, wherein
the gear cutting is performed with a hob cutter, and
in the third step, a sintering temperature is a temperature lower than a liquidus temperature, wherein the sintered gear has a periodic concave and convex shape for containing a lubricant at a tooth bottom thereof, and a periodicity of the concave and convex shape has a length of 1 mm or more.

Assignees

• Sumitomo Electric Industries
• Sumitomo Electric Sintered Alloy Ltd

Inventors

• Ishimine Tomoyuki
• Egashira Shigeki
• Shimauchi Kazunari
• Tashiro Takayuki

Classifications

• B22F5/08 Primary

  of toothed articles, e.g. gear wheels; of cam discs · CPC title

• B22F1/00

  Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties · CPC title

• B22F3/162

  Machining, working after consolidation · CPC title

• F16H55/06

  Use of materials; Use of treatments of toothed members or worms to affect their intrinsic material properties · CPC title

• F16H55/17

  Toothed wheels (worm wheels F16H55/22; chain wheels F16H55/30) · CPC title