Forged product and method of making the product

• US 7,677,134 B2
• Filed: 12/17/2007
• Issued: 03/16/2010
• Est. Priority Date: 12/20/2006
• Status: Expired due to Fees

• Current Assignee: Yamaha Hatsudoki Kabushiki Kaisha (Yamaha Corporation)
• Original Assignee: Yamaha Hatsudoki Kabushiki Kaisha (Yamaha Corporation)
• Inventors: Matsushita, Osamu, Kitsunai, Toru
• Primary Examiner(s): Vanoy; Timothy C
• Assistant Examiner(s): BERNS, DANIEL J
• Application Number:
  US11/957,612
• Publication Number:
  US 20080149231A1
• Time in Patent Office: 820 Days
• Field of Search: 148/666, 148/667, 745/518, 298/972
• US Class Current: 74/551.8
• CPC Class Codes: B21J 5/02 Die forging; Trimming by making use of special dies ; Punching during forging
• CPC Class Codes: B21K 23/00 Making other articles
• CPC Class Codes: B62K 21/04 Fork crowns
• CPC Class Codes: C22C 23/02 with aluminium as the next major constituent
• CPC Class Codes: C22C 23/04 with zinc or cadmium as the next major constituent
• CPC Class Codes: C22F 1/06 of magnesium or alloys based thereon
• CPC Class Codes: Y10T 29/49622 Vehicular structural member making
• CPC Class Codes: Y10T 74/20822 Attachments and accessories

Abstract

A forged product is made of a magnesium alloy and includes a through hole making portion to make a through hole that runs in a predetermined direction, and a bottom portion that lies on a plane intersecting with the predetermined direction. The through hole includes a first portion that has been formed by a forging process and a second portion that has been formed after the forging process. The second portion of the through hole has shifted toward the bottom portion with respect to the middle of the through hole in the predetermined direction.

Claims

1. A forged product made of a magnesium alloy, the product comprising:

a through hole making portion that defines a through hole that runs in a predetermined direction; and

a bottom portion that lies on a plane intersecting with the predetermined direction, the bottom portion of the forged product having a thickness defined by a distance from a top surface of the bottom portion to a bottom surface of the bottom portion;

wherein

the through hole includes a first portion that has been formed by a forging process and a second portion that has been formed by removing a bottom of the through hole after the forging process; and

a position of the second portion of the through hole is shifted toward the bottom portion with respect to a middle of the through hole in the predetermined direction;

wherein

the second portion of the through hole is substantially on a level with the bottom portion of the forged product; and

a thickness of the second portion of the through hole is substantially equal to the thickness of the bottom portion.

2. The forged product of claim 1, wherein a distance from the middle of the through hole in the predetermined direction to the second portion of the through hole accounts for more than about 70% of the distance from the middle of the through hole in the predetermined direction to the bottom portion.

3. The forged product of claim 1, wherein as viewed on a plane that intersects with the predetermined direction, the through hole making portion is located outside of the bottom portion with respect to the center of the forged product.

4. The forged product of claim 1, wherein the magnesium alloy has an average crystal grain size of about 150 μ

m or less.

5. The forged product of claim 1, wherein the product comprises a portion in which the magnesium alloy has an average crystal grain size of about 100 μ

m or less.

6. The forged product of claim 1, wherein the magnesium alloy includes about 10 mass % or less of aluminum.

7. The forged product of claim 1, wherein the through hole making portion is a boss with a sidewall that surrounds the through hole, and the forged product is a handlebar supporting member for motorcycles.

8. A motorcycle including the forged product of claim 1.

17. The forged product of claim 1, wherein a top surface of the second portion is substantially on a level with the top surface of the bottom portion, and a bottom surface of the second portion is substantially on a level with the bottom surface of the bottom portion.

9. A handlebar supporting member for motorcycles, the member having been formed by a forging process and comprising:

a boss with a through hole that runs in a predetermined direction; and

a bottom portion that lies on a plane intersecting with the predetermined direction, the bottom portion of the forged product having a thickness defined by a distance from a top surface of the bottom portion to a bottom surface of the bottom portion;

wherein

the through hole includes a first portion that has been formed by the forging process and a second portion that has been formed by removing a bottom of the through hole after the forging process; and

a position of the second portion of the through hole is shifted toward the bottom portion with respect to a middle of the through hole in the predetermined direction;

wherein

the second portion of the through hole is substantially on a level with the bottom portion of the forged product; and

a thickness of the second portion of the through hole is substantially equal to the thickness of the bottom portion.

18. The handlebar supporting member of claim 9, wherein a top surface of the second portion is substantially on a level with the top surface of the bottom portion, and a bottom surface of the second portion is substantially on a level with the bottom surface of the bottom portion.

10. A method of making a forged product, the method comprising the steps of:

preparing a workpiece made of a metallic material;

forging the workpiece such that the workpiece has a non-through hole running in a predetermined direction and a bottom portion lying on a plane that intersects with the predetermined direction, the bottom portion of the workpiece having a thickness defined by a distance from a top surface of the bottom portion to a bottom surface of the bottom portion; and

removing a portion of the forged workpiece, thereby turning the non-through hole into a through hole;

wherein

the step of forging is performed such that the portion of the workpiece to be removed in the step of removing has been shifted toward the bottom portion with respect to the middle of the through hole in the predetermined direction;

the non-through hole is substantially on a level with the bottom portion of the workpiece; and

a thickness of the non-through hole is substantially equal to the thickness of the bottom portion.

11. The method of claim 10, wherein as viewed in a direction in which the workpiece is pressed in the step of forging, the workpiece prepared in the step of preparing has substantially the same profile as the workpiece that has been forged in the step of forging.

12. The method of claim 11, wherein the step of preparing the workpiece includes forming the workpiece by an extrusion process.

13. The method of claim 10, wherein the step of preparing the workpiece includes preparing a workpiece made of a magnesium alloy.

14. The method of claim 13, wherein the step of forging includes forging the workpiece at an upset ratio of about 60% or more.

15. The method of claim 13, wherein the step of forging includes forging the workpiece such that the forged workpiece has a thickness of about 1 mm to about 8 mm.

16. The method of claim 13, wherein the step of forging includes forging the workpiece such that a portion of the forged workpiece has a deformation height of about 130% or more.

19. The method of claim 10, wherein a top surface of the non-through hole is substantially on a level with the top surface of the bottom portion, and a bottom surface of the non-through hole is substantially on a level with the bottom surface of the bottom portion.