Apparatus for forming a blank for finish forging for a forged crankshaft for a 4-cylinder engine, and method for manufacturing a forged crankshaft for a 4-cylinder engine using the same

Patent metadata

Field	Value
Publication number	US-10005121-B2
Application number	US-201515118127-A
Country	US
Kind code	B2
Filing date	Feb 18, 2015
Priority date	Feb 27, 2014
Publication date	Jun 26, 2018
Grant date	Jun 26, 2018

Abstract

In a forming apparatus, stationary journal dies ( 10 U, 10 B) and movable journal dies ( 11 U, 11 B) each hold and retain rough journal portions (Ja) of a preform blank ( 4 ) therebetween, and crank pin dies ( 12 ) contacts rough crank pin portions (Pa) thereof, and in this state, the movable journal dies ( 11 U, 11 B) are moved axially toward the stationary journal dies ( 10 U, 10 B) and the crank pin dies ( 12 ) are moved in the same axial direction and in an eccentric direction. With this, weighted rough arm portions (Aa) are axially compressed to reduce their thickness to that of weighted arms of a forged crankshaft, and the rough crank pin portions (Pa) are pressed in the eccentric direction to increase the amount of eccentricity to that of the crank pins of the forged crankshaft.

First claim

The invention claimed is:

1. An apparatus for forming a blank for finish forging for a forged crankshaft for a 4-cylinder engine, the apparatus configured to form, in a process of manufacturing a forged crankshaft for a 4-cylinder engine, a blank for finish forging to be subjected to finish forging by which a final shape of the forged crankshaft is obtained, from a preform blank, wherein
in the forged crankshaft,
fourth and fifth crank arms connecting with a central third journal have balance weights,
any one of first and second crank arms connecting with a first crank pin at a fore end has a balance weight, and any one of seventh and eighth crank arms connecting with a fourth crank pin at a rear end has a balance weight, and
the remaining crank arms have no balance weights,
the preform blank includes:
rough journal portions having an axial length equal to an axial length of journals of the forged crankshaft;
rough crank pin portions having an axial length equal to an axial length of crank pins of the forged crankshaft and having a smaller amount of eccentricity in an eccentric direction perpendicular to the axial direction than an amount of eccentricity of the crank pins of the forged crankshaft; and
among the crank arms of the forged crankshaft, non-weighted rough crank arm portions corresponding to non-weighted crank arms not having the balance weights, the non-weighted rough crank arm portions having an axial thickness equal to an axial thickness of the crank arms, and weighted rough crank arm portions corresponding to weighted crank arms having the balance weights, the weighted rough crank arm portions having an axial thickness greater than an axial thickness of the crank arms,
the forming apparatus, comprising:
stationary journal dies disposed at locations corresponding to a location of the third rough journal portion, the stationary journal dies configured to hold and retain the rough journal portion therebetween in the eccentric direction perpendicular to the axial direction, the stationary journal dies configured to be in contact with side surfaces of the rough crank arm portion connecting with the rough journal portion with axial movement thereof restrained,
movable journal dies disposed at locations corresponding to locations of the rough journal portions excluding the rough journal portion to be held by the stationary journal dies, the movable journal dies configured to hold and retain the rough journal portions therebetween in the eccentric direction perpendicular to the axial direction, the movable journal dies configured to move axially toward the stationary journal dies while being in contact with side surfaces of corresponding ones of the rough crank arm portions, the corresponding ones of the rough crank arm portions each connecting with a corresponding one of the rough journal portions; and
crank pin dies disposed at locations corresponding to locations of the rough crank pin portions, the crank pin dies configured to be brought into contact with the respective rough crank pin portions at inner sides thereof, the crank pin dies configured to move axially toward the stationary journal dies and in the eccentric direction perpendicular to the axial direction while being in contact with side surfaces of corresponding ones of the rough crank arm portions, the corresponding ones of the rough crank arm portions each connecting with a corresponding one of the rough crank pin portions,
wherein, in a state where the rough journal portions are held and retained by the stationary journal dies and the movable journal dies and the rough crank pin portions are contacted by the crank pin dies, the movable journal dies are moved axially, and the crank pin dies are moved axially as well as in the eccentric direction, thereby compressing the weighted rough crank arm portions in the axial direction so as to reduce the thickness thereof to the thickness of the weighted crank arms of the forged crankshaft, and pressing the rough crank pin portions in the eccentric direction so as to increase the amount of eccentricity thereof to the amount of eccentricity of the crank pins of the forged crankshaft.

2. The apparatus for forming a blank for finish forging for a forged crankshaft for a 4-cylinder engine according to claim 1 ,
wherein the crank pin dies each include an auxiliary crank pin die disposed at a location facing an outer side, opposite to the inner side, of each rough crank pin portion, the auxiliary crank pin dies configured to move axially, and
wherein the movement of the crank pin dies in the eccentric direction is controlled so that the rough crank pin portions to be eccentrically deformed reach the auxiliary crank pin dies after spaces between the stationary journal dies and the movable journal dies and corresponding ones of the crank pin dies and the auxiliary crank pin dies are filled by the axial movement of the movable journal dies as well as the axial movement of the crank pin dies and the auxiliary crank pin dies.

3. The apparatus for forming a blank for finish forging for a forged crankshaft for a 4-cylinder engine according to claim 2 ,
wherein, provided that a total length of movement of the crank pin dies in the eccentric direction is a 100% length of movement thereof, when the axial movement of the movable journal dies that are adjacent to the crank pin dies is completed, a length of movement of the crank pin dies in the eccentric direction is 90% or less of the total length of movement, and thereafter, the movement of the crank pin dies in the eccentric direction is completed.

4. The apparatus for forming a blank for finish forging for a forged crankshaft for a 4-cylinder engine according to claim 1 ,
wherein the stationary journal dies, the movable journal dies, and the crank pin dies are mounted on a press machine that is capable of being moved downward along the eccentric direction, and
wherein, by downward movement of the press machine, the stationary journal dies and the movable journal dies are caused to hold and retain the rough journal portions therebetween, and the crank pin dies are brought into contact with the rough crank pin portions; and with continued downward movement of the press machine, the movable journal dies are moved axially by wedge mechanisms, and the crank pin dies are caused to move axially by the movement of the movable journal dies.

5. The apparatus for forming a blank for finish forging for a forged crankshaft for a 4-cylinder engine according to claim 4 ,
wherein the wedge mechanisms have different wedge angles for each of the movable journal dies.

6. The apparatus for forming a blank for finish forging for a forged crankshaft for a 4-cylinder engine according to claim 4 ,
wherein the crank pin dies are coupled to a hydraulic cylinder and caused to move in the eccentric direction by driving the hydraulic cylinder.

7. The apparatus for forming a blank for finish forging for a forged crankshaft for a 4-cylinder engine according to claim 1 ,
in the forged crankshaft, the first, fourth, fifth, and eighth crank arms have balance weights, and the remaining second, third, sixth and seventh crank arm have no balance weights.

8. The apparatus for forming a blank for finish forging for a forged crankshaft for a 4-cylinder engine according to claim 1 ,
in the forged crankshaft, the second, fourth, fifth, and seventh crank arms have balance weights, and the remaining first, third, sixth, and eighth crank arms have no balance weights.

9. A method for manufacturing a forged crankshaft for a 4-cylinder engine, in which fourth and fifth crank arms connecting with a central third journal have balance weights, any one of first and second crank arms connecting with a first crank pin at a

Assignees

• Nippon Steel & Sumitomo Metal Corp

Inventors

• Okubo Junichi
• Tamura Kenji
• Yoshida Kunihiro

Classifications

• F16C3/08

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

• B21J9/027

  with punches moving along auxiliary lateral directions (B21J13/025 takes precedence) · CPC title

• B21K1/00

  Making machine elements · CPC title

• B21K1/08 Primary

  crankshafts · CPC title

• B21J5/025

  Closed die forging · CPC title