Enhanced fatigue nut

• US 5,927,921 A
• Filed: 11/11/1997
• Issued: 07/27/1999
• Est. Priority Date: 11/11/1997
• Status: Expired due to Term

• Current Assignee: SPS Technologies LLC (Berkshire Hathaway Incorporated)
• Original Assignee: SPS Technologies LLC (Berkshire Hathaway Incorporated)
• Inventors: Hukari, Ronald J.
• Primary Examiner(s): Saether, Flemming
• Application Number:
  US08/967,501
• Time in Patent Office: 623 Days
• Field of Search: 411/917, 411/427, 411/185, 411/186, 411/187
• US Class Current: 411/427
• CPC Class Codes: F16B 31/06 having regard to possibility of fatigue rupture
• CPC Class Codes: F16B 37/00 Nuts or like thread-engaging members specially shaped for rotations by a tool F16B23/00

Abstract

An enhanced fatigue nut for mating with a threaded mating component includes an exterior surface, a flanged mating end for insertion of a threaded mating component and an end opposing the flanged mating end. Disposed on the interior of the fastener may be a plurality of threads running from the flanged mating end toward the opposing end. The flanged mating end may have a load distributing profile that reduces a limiting stress on the threads of the mating component when the mating component is mated with the enhanced fatigue nut. The flanged mating end may have an end surface, a portion of which is disposed at an angular relationship with a line that is disposed perpendicular with a line that is disposed through the center of the interior of the enhanced fatigue nut. This angled portion creates a gap between the enhanced fatigue nut and another component, such as a washer, so that when the enhanced fatigue nut is mated with the mating component, the enhanced fatigue nut can bend or deflect into the gap and thereby shift the loads on the mating component to reduce the peak limiting stress on the threads of the mating component. This thereby increases the fatigue life of the mating component. The enhanced fatigue nut may also have a groove disposed in the flanged mating end that cooperates with the angled portion of the flanged mating end to reduce the limiting stress on the threads of the mating component.

Claims

1. An enhanced fatigue nut that has an exterior, the nut being for mating with a threaded mating component and for increasing a fatigue life of the mating component by reducing a limiting stress on the threads of the mating component, comprising:

a threaded cylindrical interior for mating with the threads of the mating component;

the interior having a bottom;

a mating end for insertion of the threaded mating component, the mating end comprising (i) an annular surface that defines an annular groove, the annular surface having a first portion that extends upward from the bottom to a top of the groove and a second portion that extends downward from the top towards the exterior and below the bottom the first and second portions being angled with respect to an axial centerline through the threaded cylindrical interior, and (ii) an angled flanged end that extends from the second portion to the exterior, the angled flanged end being disposed in an angular relationship with the second portion and in an angular relationship with a line that is perpendicular to the axial centerline through the threaded cylindrical interior,

the groove and the angled flanged end causing the threads of the enhanced fatigue nut to deflect when the enhanced fatigue nut is mated with the mating component and thereby causing the limiting stress on the threads of the mating component to be reduced and increasing the fatigue life of the mating component.

2. The enhanced fatigue nut of claim 1, wherein an inner diameter of the groove is within a range defined by a nominal thread diameter of the enhanced fatigue nut and the nominal thread diameter of the enhanced fatigue nut plus two thread pitches of the enhanced fatigue nut.

4. The enhanced fatigue nut of claim 1, wherein the mating end has an outside diameter that creates a surface area that is within a range of about 140% to 200% of the area defined by a nominal thread diameter of the enhanced fatigue nut.

5. The enhanced fatigue nut of claim 1, wherein the angled flanged end is disposed at an angle in the range of about 2°

-5°

with the line that is perpendicular to the centerline.

6. The enhanced fatigue nut of claim 1, wherein the enhanced fatigue nut comprises metal.

7. The enhanced fatigue nut of claim 1, further comprising a mid-section disposed between the mating end and an end opposing the mating end, the mid-section having a stiffness relative to a stiffness of the mating end that permits the threads of the enhanced fatigue nut to deflect when mated with the mating component and thereby reduce the limiting stress on the mating component.

8. The enhanced fatigue nut of claim 1, wherein the angled flanged end is disposed at an angle in the range of about 3°

-5°

with the line that is perpendicular to the centerline.

9. The enhanced fatigue nut of claim 1, wherein the angled flanged end is disposed at an angle in the range of about 4°

-5°

with the line that is perpendicular to the centerline.

3. The enhanced fatigue nut of claim I, wherein an outer diameter of the groove is within a range defined by a nominal thread diameter of the enhanced fatigue nut plus three thread pitches and the nominal thread diameter of the enhanced fatigue nut plus five thread pitches of the enhanced fatigue nut.

10. An assembly for increasing a fatigue life of a threaded mating component by reducing a limiting stress on the threads of the mating component, comprising:

an enhanced fatigue nut that has an exterior, the fatigue nut adapted for mating with the threaded mating component, comprising

(i) a threaded cylindrical interior, the interior having a bottom,

(ii) a flanged mating end, into which the threaded mating component can be inserted, that includes an annular surface, that defines an annular groove, the annular surface having a first portion that extends upward from the bottom of the interior to a top of the groove and a second portion that extends downward from the top towards the exterior and below the bottom the first and second portions being angled with respect to an axial centerline disposed through a center of the enhanced fatigue nut,

(iii) the flanged mating end having an angled portion which is angled with respect to a first line that is perpendicular with the axial centerline disposed through the center of the enhanced fatigue nut, and that is angled with respect to the second portion of the annular surface;

the mating component inserted into the flanged mating end of the enhanced fatigue nut and threaded to the threaded cylindrical interior of the enhanced fatigue nut, the angled portion of the flanged mating end and the groove causing the threads of the enhanced fatigue nut to deflect when the enhanced fatigue nut is mated with the mating component and thereby causing the limiting stress on the threads of the mating component to be reduced and increasing the fatigue life of the mating component; and

a mechanical component compressed between the flanged mating end of the enhanced fatigue nut and a joint.

11. The assembly of claim 10, wherein the mating component comprises a bolt.

12. The assembly of claim 10, wherein the mechanical component comprises a washer.

13. The assembly of claim 10, wherein an inner diameter of the groove is within a range defined by a nominal thread diameter of the enhanced fatigue nut and the nominal thread diameter of the enhanced fatigue nut plus two thread pitches of the enhanced fatigue nut.

14. The assembly of claim 10, wherein an outer diameter of the groove is within a range defined by a nominal thread diameter of the enhanced fatigue nut plus three thread pitches and the nominal thread diameter of the enhanced fatigue nut plus five thread pitches of the enhanced fatigue nut.

15. The assembly of claim 10, wherein the flanged mating end has an outer diameter that creates a surface area that is within a range of 140% to 200% of the area defined by a nominal thread diameter of the enhanced fatigue nut.

16. The assembly of claim 10, wherein the angled portion of the flanged mating end is disposed at an angle in the range of about 2°

-5°

with the first line.

17. The assembly of claim 10, further comprising a mid-section disposed between the flanged mating end and an end opposing the flanged mating end, the mid-section having a stiffness relative to the stiffness of the flanged mating end that permits the threads of the enhanced fatigue nut to deflect when mated with the mating component and thereby reduce the limiting stress on the mating component.

18. A method of mechanically connecting, comprising:

providing an enhanced fatigue nut that comprises a body, a threaded interior that has a bottom, an exterior and a flanged mating end for insertion of a threaded mating component, the flanged mating end comprising (i) an annular surface that defines an annular groove, the annular surface having a first portion that extends upward from the bottom to a top of the groove and a second portion that extends downward from the top towards the exterior and below the bottom the first and second portions being angled with respect to an axial centerline through the threaded cylindrical interior, and (ii) an angled flanged surface that extends from the second portion to the exterior, the angled flanged surface being disposed in an angular relationship with the second portion and in an angular relationship with a line that is perpendicular to a centerline through the threaded cylindrical interior, the groove and the angled flanged end causing the threads of the enhanced fatigue nut to deflect when the enhanced fatigue nut is mated with the mating component and thereby causing the limiting stress on the threads of the mating component to be reduced and increasing the fatigue life of the mating component;

contacting the angled flanged surface of the flanged mating end with a first mechanical component so that a gap is created between the flanged mating end and the first mechanical component; and

mating the threads of the mating component with the threads of the enhanced fatigue nut and thereby deflecting the enhanced fatigue nut into the gap and distributing a stress on the threads of the second mechanical component to reduce the limiting stress on the threads of the second mechanical component.