Helical groove fasteners and methods for making same

• US 20040245772A1
• Filed: 06/05/2003
• Published: 12/09/2004
• Est. Priority Date: 06/05/2003
• Status: Active Grant

• Current Assignee: SPS Technologies LLC (Berkshire Hathaway Incorporated)
• Original Assignee: SPS Technologies LLC (Berkshire Hathaway Incorporated)
• Inventors: Swim, Ollie C. Jr.
• Granted Patent: US 6,878,069 B2
• Time in Patent Office: Days
• US Class Current: 285/190
• CPC Class Codes: F16B 35/041 Specially-shaped shafts shape of thread F16B33/02

Abstract

Helical groove fasteners and methods for producing the same are provided for use in systems requiring fluid passage through the fastener. In one embodiment, the fastener includes a shank, a head, a threaded portion, and at least one groove extending through at least a portion of the threaded portion. The fastener can include a single groove or multiple grooves. In certain preferred embodiments, the helix rotation angle of the groove is selected so that the shank has a continuous diameter to facilitate the thread forming process. In preferred embodiments, the fastener is cold forged and the threads are formed using a thread rolling die.

Claims

1. A fastener comprising:

a shank having a length, a first end, and a second end;

a head proximate said first end;

at least one threaded portion disposed between said first and said second end, said threaded portion comprising at least one thread having a thread root that forms a minor diameter and a thread crest that forms a major diameter; and

at least one groove extending through at least a portion of said threaded portion, said groove having a groove cross-sectional area and forming a helix on said shank.

2. The fastener of claim 1 wherein said groove extends to said second end of said shank.

3. The fastener of claim 1 further comprising a body between said threaded portion and said head.

4. The fastener of claim 3 wherein said groove extends through at least a portion of said body.

5. The fastener of claim 1 wherein said helix has a helix rotation angle between about 60 and 120 degrees.

6. The fastener of claim 1 wherein said helix has a pitch between about two times and about six times said length of said shank.

7. The fastener of claim 1 wherein said groove further comprises a groove root, a first flank, a second flank, and a groove flank angle between said first flank and said second flank.

8. The fastener of claim 7 wherein said thread root intersects said first and said second flank, and said groove root is within said minor diameter.

9. The fastener of claim 7 wherein said groove cross-sectional area of said groove is about 2 to about 30 percent of the cross-sectional area of a circle formed by said minor diameter.

10. The fastener of claim 7 wherein said groove flank angle is between about 70 and 110 degrees.

11. The fastener of claim 7 wherein said groove flank angle is between about 85 and 95 degrees.

12. The fastener of claim 7 wherein said root comprises a root radius that is tangential to said first flank and said second flank.

13. The fastener of claim 7 further comprising a first crest radius that is tangential to said first flank and said thread crest and a second crest radius that is tangential to said second flank and said thread crest.

14. The fastener of claim 1 further comprising a plurality of grooves extending through said shank and said threaded portion.

15. The fastener of claim 1 wherein said head comprises a flange.

16. A method for manufacturing a fastener comprising the steps of:

providing a blank comprising a shank having a first end and a second end, and a head proximate said first end of said shank;

providing a fastener die comprising a cylindrical surface and at least one helical rib with a helix rotation angle between about 60 and 120 degrees, said helical rib comprising a first flank surface, a second flank surface, a rib flank angle, and a transition;

forming a groove in said blank by applying a first force to said blank along the axis of said cylindrical surface and pushing said blank into said fastener die; and

applying a second force to remove said blank from said fastener die.

17. The method of claim 16 further comprising the step of creating threads on at least a portion of said shank proximate said second end.

18. The method of claim 17 wherein said threads are formed by a thread rolling process.

19. The method of claim 18 further comprising the step of heat treating the fastener.

20. The method of claim 19 wherein said heat treating is performed prior to said thread rolling.

21. The method of claim 16 wherein said second force comprises a torque applied to said blank about the axis of said cylindrical surface.

22. The method of claim 21 wherein said second force further comprises pressure applied to said second end of said shank along the axis of said cylindrical surface.

23. The method of claim 16 wherein said fastener die comprises between one and three ribs.

24. A fastener die comprising a cylindrical surface and at least one helical rib with a helix rotation angle between about 60 and 120 degrees, said helical rib comprising a first flank surface, a second flank surface, a rib flank angle, and a transition.

25. The fastener die of claim 24 further comprising between one and three helical ribs.

26. The fastener die of claim 24 wherein said rib flank angle is between about 85 and 95 degrees.