Crankshaft and method of manufacturing the same

Patent metadata

Field	Value
Publication number	US-12180995-B2
Application number	US-202218264496-A
Country	US
Kind code	B2
Filing date	Mar 4, 2022
Priority date	Mar 29, 2021
Publication date	Dec 31, 2024
Grant date	Dec 31, 2024

Abstract

A crankshaft with improved fatigue strength is provided. A crankshaft 10 includes journals 11 , pins 12 , and fillets 14 , each fillet 14 having a residual stress distribution where the residual stresses are compressive residual stresses from the surface down to a depth of at least 300 μm, the maximum value of the compressive residual stress being not lower than 1000 MPa, the surface roughness Rz being lower than 3.00 μm.

First claim

The invention claimed is:

1. A crankshaft comprising a journal, a pin, and a fillet,
the fillet having a residual stress distribution where a residual stress is a compressive residual stress from a surface down to a depth of at least 300 μm, a maximum value of the compressive residual stress being not lower than 1000 MPa, a surface roughness Rz being lower than 3.00 μm.

2. The crankshaft according to claim 1 , wherein the compressive residual stress is highest at a depth in the fillet not smaller than 250 μm from the surface.

3. The crankshaft according to claim 1 , wherein a hardness of the fillet at a depth of 250 μm from the surface is not lower than HV 650.

4. A method of manufacturing the crankshaft according to claim 1 , comprising:
preparing an intermediate product of the crankshaft;
quenching the intermediate product;
grinding the quenched intermediate product; and
rolling the fillet of the ground intermediate product with a Hertzian stress not less than 550 kgf/mm 2 .

5. The method of manufacturing a crankshaft according to claim 4 , wherein the surface roughness Rz of the fillet after the grinding and before the rolling is lower than 1.00 μm.

Assignees

• Nippon Steel Corp

Inventors

• Abe Tatsuhiko
• Sueyasu Yoko

Classifications

• C21D8/00

  Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment (hardening articles or materials formed by forging or rolling with no further heating beyond that required for the formation C21D1/02) · CPC title

• F16C2360/22

  Internal combustion engines · CPC title

• F16C2240/18

  Stress · CPC title

• F16C2220/70

  by grinding · CPC title

• F16C2204/74

  with manganese as the next major constituent · CPC title