METHOD FOR PRODUCING FORGED CRANKSHAFT

• US 20180056372A1
• Filed: 03/31/2016
• Published: 03/01/2018
• Est. Priority Date: 04/03/2015
• Status: Active Grant

• Current Assignee: Nippon Steel Corporation
• Original Assignee: Nippon Steel & Sumitomo Metal Corporation (Nippon Steel Corporation)
• Inventors: TAKAMOTO, Sho, TAMURA, Kenji, YAMASHITA, Tomohisa, YABUNO, Kunihiro, YOSHINO, Ken, KUROKAWA, Hiroyuki, OKUBO, Junichi, ISHIHARA, Koichiro
• Granted Patent: US 10,441,995 B2
• Time in Patent Office: Days
• CPC Class Codes: B21J 5/027 Trimming
• CPC Class Codes: B21K 1/08 crankshafts
• CPC Class Codes: B23P 15/00 Making specific metal objects by operations not covered by a single other subclass or a group in this subclass
• CPC Class Codes: B23P 2700/07 Crankshafts
• CPC Class Codes: F16C 3/08 made in one piece features relating to lubrication F16C3/14, to cooling F16C3/16

Abstract

The disclosed production method includes a die forging step of obtaining a forged blank with flash having a crankshaft shape, and a trimming step of removing the flash from the forged blank while nipping the forged blank with a pair of holding dies. In the forged blank, at least one of the rough crank arms have, in a region near an adjacent rough pin, a first excess portion protruding from an outer periphery of a side portion of the rough crank arm. When the forged blank is nipped with the pair of holding dies, the first excess portion is deformed by the pair of holding dies to bulge toward an adjacent rough journal.

Claims

1. A method for producing a forged crankshaft including journals serving as a center of rotation, pins decentered from the journals, and crank arms connecting the journals and the pins, wherein

the forged crankshaft further includes counterweights integrated with all or some of the crank arms,

the method comprising:

a die forging step of obtaining a forged blank with flash having a crankshaft shape; and

a trimming step of removing the flash from the forged blank while nipping the forged blank with a pair of holding dies, wherein;

the forged blank includes rough journals, rough pins, rough crank arms, and rough counterweights, which correspond to the journals, the pins, the crank arms, and the counterweights of the forged crankshaft, respectively;

at least one of the rough crank arms has, in a region near an adjacent one of the rough pins, a first excess portion protruding from an outer periphery of a side portion of the rough crank arm; and

when the forged blank is nipped with the pair of holding dies in the trimming step, the first excess portion is deformed by the pair of holding dies to bulge toward an adjacent one of the rough journals.

2. The method for producing a forged crankshaft according to claim 1, wherein

the rough crank arm has, in the region near the adjacent rough pin, first excess portions respectively protruding from outer peripheries of two side portions of the rough crank arm.

3. The method for producing a forged crankshaft according to claim 1, wherein

in the trimming step, the first excess portion is deformed by the pair of holding dies to bulge toward the adjacent rough journal while a holder is holding a lower surface of the flash;

and

the holder moves along with a movement of the pair holding dies while keeping holding the lower surface of the flash.

4. The method for producing a forged crankshaft according to claim 1, wherein

in the trimming step, the first excess portion is deformed by crushing or bending.

5. The method for producing a forged crankshaft according to claim 1, wherein

at least one of the rough crank arms has, in a region near an adjacent one of the rough journals, a second excess portion protruding from an outer periphery of a side portion of the rough crank arm;

and

when the forged blank is nipped with the pair of holding dies in the trimming step, the second excess portion is deformed by the pair of holding dies to bulge toward the adjacent rough pin.

6. The method for producing a forged crankshaft according to claim 5, wherein

the rough crank arm has, in the region near the adjacent rough journal, second excess portions respectively protruding from outer peripheries of two side portions of the rough crank arm.

7. The method for producing a forged crankshaft according to claim 5, wherein

the rough crank arm having the second excess portion is the rough crank arm incorporating a rough counterweight.

8. The method for producing a forged crankshaft according to claim 5, wherein

the rough crank arm having the second excess portion is the rough crank arm not incorporating a rough counterweight.

9. The method for producing a forged crankshaft according to claim 5, wherein

in the trimming step, the second excess portion is deformed by crushing or bending.

10. The method for producing a forged crankshaft according to claim 2, wherein

in the trimming step, the first excess portion is deformed by the pair of holding dies to bulge toward the adjacent rough journal while a holder is holding a lower surface of the flash;

and

the holder moves along with a movement of the pair holding dies while keeping holding the lower surface of the flash.

11. The method for producing a forged crankshaft according to claim 2, wherein

at least one of the rough crank arms has, in a region near an adjacent one of the rough journals, a second excess portion protruding from an outer periphery of a side portion of the rough crank arm;

and

when the forged blank is nipped with the pair of holding dies in the trimming step, the second excess portion is deformed by the pair of holding dies to bulge toward the adjacent rough pin.

12. The method for producing a forged crankshaft according to claim 3, wherein

at least one of the rough crank arms has, in a region near an adjacent one of the rough journals, a second excess portion protruding from an outer periphery of a side portion of the rough crank arm;

and

when the forged blank is nipped with the pair of holding dies in the trimming step, the second excess portion is deformed by the pair of holding dies to bulge toward the adjacent rough pin.

13. The method for producing a forged crankshaft according to claim 4, wherein

at least one of the rough crank arms has, in a region near an adjacent one of the rough journals, a second excess portion protruding from an outer periphery of a side portion of the rough crank arm;

and

when the forged blank is nipped with the pair of holding dies in the trimming step, the second excess portion is deformed by the pair of holding dies to bulge toward the adjacent rough pin.

14. The method for producing a forged crankshaft according to claim 10, wherein

at least one of the rough crank arms has, in a region near an adjacent one of the rough journals, a second excess portion protruding from an outer periphery of a side portion of the rough crank arm;

and

when the forged blank is nipped with the pair of holding dies in the trimming step, the second excess portion is deformed by the pair of holding dies to bulge toward the adjacent rough pin.

15. The method for producing a forged crankshaft according to claim 11, wherein

the rough crank arm has, in the region near the adjacent rough journal, second excess portions respectively protruding from outer peripheries of two side portions of the rough crank arm.

16. The method for producing a forged crankshaft according to claim 12, wherein

the rough crank arm has, in the region near the adjacent rough journal, second excess portions respectively protruding from outer peripheries of two side portions of the rough crank arm.

17. The method for producing a forged crankshaft according to claim 13, wherein

the rough crank arm has, in the region near the adjacent rough journal, second excess portions respectively protruding from outer peripheries of two side portions of the rough crank arm.

18. The method for producing a forged crankshaft according to claim 14, wherein

the rough crank arm has, in the region near the adjacent rough journal, second excess portions respectively protruding from outer peripheries of two side portions of the rough crank arm.