Method of manufacturing die forged crankshaft

Patent metadata

Field	Value
Publication number	US-9937550-B2
Application number	US-201514597307-A
Country	US
Kind code	B2
Filing date	Jan 15, 2015
Priority date	Jul 27, 2012
Publication date	Apr 10, 2018
Grant date	Apr 10, 2018

Abstract

A method of manufacturing a die forged crankshaft to be mounted in a two or more cylinder reciprocating apparatus includes: an upsetting step that includes upsetting a billet having a constant cross-sectional area along an entire length thereof to form a blank having an enlarged cross-sectional area at a region between a portion to be formed into a leading crank arm of the crankshaft and a portion to be formed into a trailing crank arm thereof; a die forging step that includes die forging the blank formed in the upsetting step to form a forged blank having a shape of the crankshaft with a flash; and a trimming step that includes trimming the flash from the forged blank formed in the die forging step. This makes it possible to improve the material utilization and to use a billet having a cross-sectional size as small as possible.

First claim

What is claimed is:

1. A method of manufacturing a die forged crankshaft to be mounted in an at least two cylinder reciprocating apparatus, the method comprising:
an upsetting step that includes upsetting a billet having a constant cross-sectional area along an entire length thereof to form a blank having a uniformly enlarged cross-sectional area at a region between a portion to be formed into a leading crank arm of the crankshaft and a portion to be formed into a trailing crank arm of the crankshaft;
a die forging step that includes die forging the blank formed in the upsetting step to form a forged blank having a shape of the crankshaft with a flash; and
a trimming step that includes trimming the flash from the forged blank formed in the die forging step.

2. The method of manufacturing a die forged crankshaft according to claim 1 , further comprising:
a preforming step prior to the die forging step, the preforming step including: partially pressing the blank in accordance with the shape of the crankshaft and distributing a volume of the blank at least in a longitudinal direction thereof and a direction perpendicular to the longitudinal direction.

3. The method of manufacturing a die forged crankshaft according to claim 1 ,
wherein the crankshaft includes a disc-shaped crank arm that is coaxial with the central axis of the crankshaft, and,
the upsetting step is performed in such a manner that the blank has a portion to be formed into the disc-shaped crank arm, the portion having a further enlarged cross sectional area.

4. The method of manufacturing a die forged crankshaft according to claim 3 , further comprising:
a preforming step prior to the die forging step, the preforming step including: partially pressing the blank in accordance with the shape of the crankshaft and distributing a volume of the blank at least in a longitudinal direction thereof and a direction perpendicular to the longitudinal direction.

Assignees

• Nippon Steel & Sumitomo Metal Corp

Inventors

• Fukuyasu Tomihiko
• Tanimoto Nobutaka
• Okubo Junichi
• Yoshida Kunihiro

Classifications

• B21J5/08

  Upsetting · CPC title

• Y10T29/49286

  Crankshaft making · CPC title

• B21K1/08 Primary

  crankshafts · CPC title

• F16C3/08

  made in one piece (features relating to lubrication F16C3/14, to cooling F16C3/16) · CPC title

• B21J5/027

  Trimming · CPC title