ADVANCED NUT AND BOLT
A fastener including a bolt having an elongated shank having a first end, a second end opposite the first end, and a threaded portion having an external bolt thread, the bolt thread including a bolt pitch. The fastener includes a nut having a first end, a second end opposite the first end of the nut, and an internal nut thread extending between the first and second ends of the nut and adapted to engage threadedly the bolt thread of the bolt. The nut thread includes a nut pitch and a hardness that changes gradationally between the first and second ends of the nut. The bolt pitch of the bolt thread of the bolt is mismatched with the nut pitch of the nut thread of the nut.
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This application is a Section 111(a) application relating to and claiming the benefit of commonly owned, co-pending U.S. Provisional Application Ser. No. 61/908,922 filed on Nov. 26, 2013, the disclosure of which is incorporated by reference herein in its entirety.
FIELD OF THE INVENTIONThe present invention relates to a fastening system and, more particularly, to a vibration-resistant fastening system that includes a nut and a high fatigue strength bolt.
BACKGROUND OF THE INVENTIONA free running or prevailing torque nut that forms a vibration proof lock when tightened is desirable. The lock is formed by allowing the bolt thread to embed into the relatively softer nut thread. Reducing material weight and costs of the nut would be desirable.
SUMMARY OF THE INVENTIONIn an embodiment, a fastener, comprising a bolt including an elongated shank having a first end, a second end opposite the first end, and a threaded portion having an external bolt thread, wherein the bolt thread includes a bolt pitch; and a nut including a first end, a second end opposite the first end of the nut, and an internal nut thread extending between the first and second ends of the nut and adapted to engage threadedly the bolt thread of the bolt, wherein the nut thread includes a nut pitch, wherein the bolt pitch of the bolt thread of the bolt is mismatched with the nut pitch of the nut thread of the nut. In an embodiment, the nut pitch of the nut thread of the nut is shorter than the bolt pitch of the bolt thread of the bolt. In an embodiment, when the nut thread of the nut engages the bolt thread of the bolt, an initial contact and engagement between the nut thread and the bolt thread is located at a pitch of the nut pitch that is proximate to the first end of the nut. In an embodiment, the nut pitch of the nut thread of the nut is longer than the bolt pitch of the bolt thread of the bolt. In an embodiment, when the nut thread of the nut engages the bolt thread of the bolt, an initial contact and engagement between the nut thread and the bolt thread is located at a pitch of the nut pitch that is proximate to the second end of the nut. In an embodiment, the nut includes a flange located at the first end thereof.
In an embodiment, a bolt including an elongated shank having a first end, a second end opposite the first end, and a threaded portion having an external bolt thread, wherein the bolt thread includes a bolt pitch; and a nut including a nut body having a first end, a second end opposite the first end of the nut body, and a countersunk aperture, an insert positioned within the countersunk aperture, and an internal nut thread extending between the first and second ends of the nut body and adapted to engage threadedly the bolt thread of the bolt, wherein the nut thread includes a nut pitch, wherein the bolt pitch of the bolt thread of the bolt is mismatched with the nut pitch of the nut thread of the nut.
In an embodiment, the nut pitch of the nut thread of the nut is shorter than the bolt pitch of the bolt thread of the bolt. In an embodiment, the countersunk aperture is located at the second end of the nut body. In an embodiment, the nut body is made from a first material and the insert is made from a second material that is softer than the first material. In an embodiment, when the nut thread of the nut engages the bolt thread of the bolt, an initial contact and engagement between the nut thread and the bolt thread is located at a pitch of the nut pitch that is proximate to the second end of the nut.
In an embodiment, countersunk aperture is located at the first end of the nut body. In an embodiment, the nut body is made from a first material and the insert is made from a second material that is harder than the first material. In an embodiment, the nut thread of the nut engages the bolt thread of the bolt, an initial contact and engagement between the nut thread and the bolt thread is located at a pitch of the nut pitch that is proximate to the second end of the nut.
In an embodiment, the nut pitch of the nut thread of the nut is longer than the bolt pitch of the bolt thread of the bolt. In an embodiment, the countersunk aperture is located at the second end of the nut body. In an embodiment, the nut body is made from a first material and the insert is made from a second material that is harder than the first material. In an embodiment, the nut thread of the nut engages the bolt thread of the bolt, an initial contact and engagement between the nut thread and the bolt thread is located at a pitch of the nut pitch that is proximate to the first end of the nut.
In an embodiment, the countersunk aperture is located at the first end of the nut body. In an embodiment, the nut body is made from a first material and the insert is made from a second material that is softer than the first material. In an embodiment, the nut thread of the nut engages the bolt thread of the bolt, an initial contact and engagement between the nut thread and the bolt thread is located at a pitch of the nut pitch that is proximate to the first end of the nut.
In an embodiment, a nut, comprising a first end, a second end opposite the first end, an internal nut thread extending from the first end to the second end, and a hardness, wherein the hardness gradationally changes between the first and second ends. In an embodiment, the nut includes a first hardness area extending between the first end and a first boundary located intermediate the first and second ends, a second hardness area extending from the first boundary to a second boundary located distal from the first boundary and towards the second end, and a third hardness area extending from the first boundary to the second end. In an embodiment, the hardness within the first hardness area includes a first hardness, the hardness within the second hardness area includes a second hardness, and the hardness within the third hardness area includes a third hardness. In an embodiment, the first hardness is a range of approximately Rc 20 to approximately Rc 60, the second hardness is a range of approximately Rb 20 to approximately Rc 60, and the third hardness is in a range of approximately Rb 20 to approximately Rb 100. In an embodiment, the hardness increases gradually from the first end to the second end. In an embodiment, a transition from the first hardness to the second hardness is abrupt, and wherein a transition from the second hardness to the third hardness is abrupt.
In another embodiment, the first hardness is in a range of approximately Rb 20 to approximately Rb 100, the second hardness is a range of approximately Rb 20 to approximately Rc 60, and the third hardness is in a range of approximately Rc 20 to approximately Rc 60. In an embodiment, the hardness increases gradually from the second end to the first end. In an embodiment, a transition from the first hardness to the second hardness is abrupt, and wherein a transition from the second hardness to the third hardness is abrupt.
In an embodiment, at least one portion of the nut thread located proximate to the second end is locally softened, and a remaining portion of the nut thread is hardened. In an embodiment, the at least one portion of the nut thread includes a length that is approximately equal to at least a portion of a pitch thread length of the nut thread. In an embodiment, the at least one portion of the nut thread includes a length that is approximately equal to one pitch thread length of the nut thread. In an embodiment, the at least one portion of the nut thread includes a length that is approximately equal to a plurality of pitch thread lengths of the nut thread. In an embodiment, the at least one portion of the nut thread includes a length that is within a range between one pitch thread length of the nut thread and two pitch thread lengths of the nut thread.
In an embodiment, the engagement between the nut thread and the bolt thread provides a visual indication of the amount of clamp generated.
In an embodiment, a fastener, comprising a bolt including an elongated shank having a first end, a second end opposite the first end, and a threaded portion having a an external bolt thread, wherein the bolt thread includes a bolt pitch; and a nut including a first end, a second end opposite the first end of the nut, a an internal nut thread extending between the first and second ends of the nut and adapted to engage threadedly the bolt thread of the bolt, wherein the nut thread includes a nut pitch, and a hardness that changes gradationally between the first and second ends of the nut, wherein the bolt pitch of the bolt thread of the bolt is mismatched with the nut pitch of the nut thread of the nut.
In an embodiment, the nut pitch of the nut thread of the nut is shorter than the bolt pitch of the bolt thread of the bolt. In an embodiment, when the nut thread of the nut engages the bolt thread of the bolt, an initial contact and engagement between the nut thread and the bolt thread is located at a pitch of the nut pitch that is proximate to the first end of the nut. In an embodiment, the nut pitch of the nut thread of the nut is longer than the bolt pitch of the bolt thread of the bolt. In an embodiment, the nut thread of the nut engages the bolt thread of the bolt, an initial contact and engagement between the nut thread and the bolt thread is located at a pitch of the nut pitch that is proximate to the second end of the nut. In an embodiment, the nut includes a flange located at the first end thereof.
In an embodiment, the nut includes a first hardness area extending between the first end and a first boundary located intermediate the first and second ends, a second hardness area extending from the first boundary to a second boundary located distal from the from the first boundary and towards the second end, and a third hardness area extending from the first boundary to the second end. In an embodiment, the hardness within the first hardness area includes a first hardness, the hardness within the second hardness area includes a second hardness, and the hardness within the third hardness area includes a third hardness. In an embodiment, the first hardness is a range of approximately Rc 20 to approximately Rc 60, the second hardness is a range of approximately Rb 20 to approximately Rc 60, and the third hardness is in a range of approximately Rb 20 to approximately Rb 100. In an embodiment, the hardness increases gradually from the first end to the second end. In an embodiment, a transition from the first hardness to the second hardness is abrupt, and wherein a transition from the second hardness to the third hardness is abrupt.
In another embodiment, the first hardness is in a range of approximately Rb 20 to approximately Rb 100, the second hardness is a range of approximately Rb 20 to approximately Rc 60, and the third hardness is in a range of approximately Rc 20 to approximately Rc 60. In an embodiment, the hardness increases gradually from the second end to the first end. In an embodiment, a transition from the first hardness to the second hardness is abrupt, and wherein a transition from the second hardness to the third hardness is abrupt.
In an embodiment, the nut wherein at least one portion of the nut thread located proximate to the second end is locally softened, and a remaining portion of the nut thread is hardened. In an embodiment, at least one portion of the nut thread includes a length that is approximately equal to at least a portion of a pitch thread length of the nut thread. In an embodiment, the at least one portion of the nut thread includes a length that is approximately equal to one pitch thread length of the nut thread. In an embodiment, the at least one portion of the nut thread includes a length that is approximately equal to a plurality of pitch thread lengths of the nut thread. In an embodiment, the at least one portion of the nut thread includes a length that is within a range between one pitch thread length of the nut thread and two pitch thread lengths of the nut thread.
Referring to
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In an embodiment, the bolt 12 is made from 4140 steel. In another embodiment, the bolt 12 is made from 50B35 steel. In another embodiment, the bolt 12 is made from stainless steel. In another embodiment, the bolt 12 is made from titanium. In another embodiment, the bolt 12 is made from aluminum.
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In another embodiment, the nut thread 30 includes a nut pitch having a length that is longer than a length of the bolt pitch of the bolt thread 26. In another embodiment, the nut thread 30 includes a nut pitch having a length that is longer than a length of a bolt pitch of the bolt thread 26. In another embodiment,
In an embodiment, the nut 14 is made from 1045 steel. In another embodiment, the nut 14 is made from 1010 steel. In another embodiment, the nut 14 is made from 1215 steel. In another embodiment, the nut 14 is made from aluminum.
In an embodiment, by implementing a thread pitch mismatch between the bolt thread 26 and the nut thread 30, the fastener 10 is able to achieve lock creation (vibration resistance) at lower clamp loads and at lower torque. In an embodiment, this mismatch concentrates the initial clamp at one end of the nut thread 30 and incrementally engages more thread length as the clamp increases, as shown in
In an embodiment, the flange 115 of the nut 114 shown in
In the embodiment shown in
In the embodiment shown in
In an embodiment, the nut 114 material is 1045 steel. In another embodiment, the nut 14 is made from 1010 steel. In another embodiment, the nut 14 is made from 1215 steel. In another embodiment, the nut 14 is made from aluminum. In an embodiment, the nut thread 130 lowers the minimum clamp load in a range of about 20% to 25% of the target clamp. In another embodiment, the nut thread 130 lowers the minimum clamp load about 50% of the target clamp. In an embodiment, the nut thread 130 has a nut pitch that is shorter than the bolt pitch of the bolt thread 126, therefore allowing the nut thread 130 to embed into the bolt thread 126 before the flanks of the nut thread 130 contact the bolt thread 126.
In an embodiment, the mismatch of the nut pitch of the nut thread 130 and the bolt pitch of the bolt thread 126 allows for a rough field estimation of the clamp being generated by the installation method. This estimation can be made by observing the amount of thread engagement between the nut thread 130 and the bolt thread 126. As an example, 1⅜ inch nuts 114 were used so the degree of embedment was easier to observe. Each of these nuts 114 was installed in a Skidmore Wilhelm test fixture at four clamp loads (60,000 lbf, 80,000 lbf, 100,000 lbf, and 120,000 lbf). The length of embedment would then be a rough indicator of the clamp achieved, which is helpful in evaluating the quality of the installation without instrumentation.
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It will be understood that the embodiments described herein are merely exemplary and that a person skilled in the art may make many variations and modifications without departing from the spirit and scope of the invention. For instance, each of the nuts 14, 114, 214, 314 described above can be substituted with a pre-tapped hole located within a structure. All such variations and modifications are intended to be included within the scope of the invention as defined in the appended claims.
Claims
1. A fastener, comprising:
- a bolt including an elongated shank having a first end, a second end opposite the first end, and a threaded portion having an external bolt thread, wherein the bolt thread includes a bolt pitch; and
- a nut including a first end, a second end opposite the first end of the nut, and an internal nut thread extending between the first and second ends of the nut and adapted to engage threadedly the bolt thread of the bolt, wherein the nut thread includes a nut pitch,
- wherein the bolt pitch of the bolt thread of the bolt is mismatched with the nut pitch of the nut thread of the nut.
2. The fastener of claim 1, wherein the nut pitch of the nut thread of the nut is shorter than the bolt pitch of the bolt thread of the bolt.
3. The fastener of claim 2, wherein when the nut thread of the nut engages the bolt thread of the bolt, an initial contact and engagement between the nut thread and the bolt thread is located at a pitch of the nut pitch that is proximate to the first end of the nut.
4. The fastener of claim 1, wherein the nut pitch of the nut thread of the nut is longer than the bolt pitch of the bolt thread of the bolt.
5. The fastener of claim 4, wherein when the nut thread of the nut engages the bolt thread of the bolt, an initial contact and engagement between the nut thread and the bolt thread is located at a pitch of the nut pitch that is proximate to the second end of the nut.
6. The fastener of claim 1, wherein the nut includes a flange located at the first end thereof.
7. A fastener, comprising:
- a bolt including an elongated shank having a first end, a second end opposite the first end, and a threaded portion having an external bolt thread, wherein the bolt thread includes a bolt pitch; and
- a nut including a nut body having a first end, a second end opposite the first end of the nut body, and a countersunk aperture, an insert positioned within the countersunk aperture, and an internal nut thread extending between the first and second ends of the nut body and adapted to engage threadedly the bolt thread of the bolt, wherein the nut thread includes a nut pitch,
- wherein the bolt pitch of the bolt thread of the bolt is mismatched with the nut pitch of the nut thread of the nut.
8. The fastener of claim 7, wherein the nut pitch of the nut thread of the nut is shorter than the bolt pitch of the bolt thread of the bolt.
9. The fastener of claim 8, wherein the countersunk aperture is located at the second end of the nut body.
10. The fastener of claim 9, wherein the nut body is made from a first material and the insert is made from a second material that is softer than the first material.
11. The fastener of claim 10, wherein when the nut thread of the nut engages the bolt thread of the bolt, an initial contact and engagement between the nut thread and the bolt thread is located at a pitch of the nut pitch that is proximate to the second end of the nut.
12. The fastener of claim 8, wherein the countersunk aperture is located at the first end of the nut body.
13. The fastener of claim 12, wherein the nut body is made from a first material and the insert is made from a second material that is harder than the first material.
14. The fastener of claim 13, wherein when the nut thread of the nut engages the bolt thread of the bolt, an initial contact and engagement between the nut thread and the bolt thread is located at a pitch of the nut pitch that is proximate to the second end of the nut.
15. The fastener of claim 7, wherein the nut pitch of the nut thread of the nut is longer than the bolt pitch of the bolt thread of the bolt.
16. The fastener of claim 15, wherein the countersunk aperture is located at the second end of the nut body.
17. The fastener of claim 16, wherein the nut body is made from a first material and the insert is made from a second material that is harder than the first material.
18. The fastener of claim 17, wherein when the nut thread of the nut engages the bolt thread of the bolt, an initial contact and engagement between the nut thread and the bolt thread is located at a pitch of the nut pitch that is proximate to the first end of the nut.
19. The fastener of claim 15, wherein the countersunk aperture is located at the first end of the nut body.
20. The fastener of claim 19, wherein the nut body is made from a first material and the insert is made from a second material that is softer than the first material.
21. The fastener of claim 20, wherein when the nut thread of the nut engages the bolt thread of the bolt, an initial contact and engagement between the nut thread and the bolt thread is located at a pitch of the nut pitch that is proximate to the first end of the nut.
22. A nut, comprising:
- a first end, a second end opposite the first end, an internal nut thread extending from the first end to the second end, and a hardness, wherein the hardness gradationally changes between the first and second ends.
23. The nut of claim 22, wherein the nut includes a first hardness area extending between the first end and a first boundary located intermediate the first and second ends, a second hardness area extending from the first boundary to a second boundary located distal from the first boundary and towards the second end, and a third hardness area extending from the first boundary to the second end.
24. The nut of claim 23, wherein the hardness within the first hardness area includes a first hardness, the hardness within the second hardness area includes a second hardness, and the hardness within the third hardness area includes a third hardness.
25. The nut of claim 24, wherein the first hardness is a range of approximately Rc 20 to approximately Rc 60, the second hardness is a range of approximately Rb 20 to approximately Rc 60, and the third hardness is in a range of approximately Rb 20 to approximately Rb 100.
26. The nut of claim 25, wherein the hardness increases gradually from the first end to the second end.
27. The nut of claim 25, wherein a transition from the first hardness to the second hardness is abrupt, and wherein a transition from the second hardness to the third hardness is abrupt.
28. The nut of claim 24, wherein the first hardness is in a range of approximately Rb 20 to approximately Rb 100, the second hardness is a range of approximately Rb 20 to approximately Rc 60, and the third hardness is in a range of approximately Rc 20 to approximately Rc 60.
29. The nut of claim 28, wherein the hardness increases gradually from the second end to the first end.
30. The nut of claim 28, wherein a transition from the first hardness to the second hardness is abrupt, and wherein a transition from the second hardness to the third hardness is abrupt.
31. The nut of claim 24, wherein at least one portion of the nut thread located proximate to the second end is locally softened, and a remaining portion of the nut thread is hardened.
32. The nut of claim 31, wherein the at least one portion of the nut thread includes a length that is approximately equal to at least a portion of a pitch thread length of the nut thread.
33. The nut of claim 31, wherein the at least one portion of the nut thread includes a length that is approximately equal to one pitch thread length of the nut thread.
34. The nut of claim 31, wherein the at least one portion of the nut thread includes a length that is approximately equal to a plurality of pitch thread lengths of the nut thread.
35. The nut of claim 31, wherein the at least one portion of the nut thread includes a length that is within a range between one pitch thread length of the nut thread and two pitch thread lengths of the nut thread.
36. The nut of claim 22, wherein the engagement between the nut thread and the bolt thread provides a visual indication of the amount of clamp generated.
37. A fastener, comprising:
- a bolt including an elongated shank having a first end, a second end opposite the first end, and a threaded portion having a an external bolt thread, wherein the bolt thread includes a bolt pitch; and
- a nut including a first end, a second end opposite the first end of the nut, a an internal nut thread extending between the first and second ends of the nut and adapted to engage threadedly the bolt thread of the bolt, wherein the nut thread includes a nut pitch, and a hardness that changes gradationally between the first and second ends of the nut,
- wherein the bolt pitch of the bolt thread of the bolt is mismatched with the nut pitch of the nut thread of the nut.
38. The fastener of claim 37, wherein the nut pitch of the nut thread of the nut is shorter than the bolt pitch of the bolt thread of the bolt.
39. The fastener of claim 38, wherein when the nut thread of the nut engages the bolt thread of the bolt, an initial contact and engagement between the nut thread and the bolt thread is located at a pitch of the nut pitch that is proximate to the first end of the nut.
40. The fastener of claim 37, wherein the nut pitch of the nut thread of the nut is longer than the bolt pitch of the bolt thread of the bolt.
41. The fastener of claim 40, wherein when the nut thread of the nut engages the bolt thread of the bolt, an initial contact and engagement between the nut thread and the bolt thread is located at a pitch of the nut pitch that is proximate to the second end of the nut.
42. The fastener of claim 37, wherein the nut includes a flange located at the first end thereof.
43. The fastener of claim 42, wherein the nut includes a first hardness area extending between the first end and a first boundary located intermediate the first and second ends, a second hardness area extending from the first boundary to a second boundary located distal from the from the first boundary and towards the second end, and a third hardness area extending from the first boundary to the second end.
44. The fastener of claim 43, wherein the hardness within the first hardness area includes a first hardness, the hardness within the second hardness area includes a second hardness, and the hardness within the third hardness area includes a third hardness.
45. The fastener of claim 44, wherein the first hardness is a range of approximately Rc 20 to approximately Rc 60, the second hardness is a range of approximately Rb 20 to approximately Rc 60, and the third hardness is in a range of approximately Rb 20 to approximately Rb 100.
46. The fastener of claim 45, wherein the hardness increases gradually from the first end to the second end.
47. The fastener of claim 45, wherein a transition from the first hardness to the second hardness is abrupt, and wherein a transition from the second hardness to the third hardness is abrupt.
48. The fastener of claim 44, wherein the first hardness is in a range of approximately Rb 20 to approximately Rb 100, the second hardness is a range of approximately Rb 20 to approximately Rc 60, and the third hardness is in a range of approximately Rc 20 to approximately Rc 60.
49. The fastener of claim 48, wherein the hardness increases gradually from the second end to the first end.
50. The fastener of claim 48, wherein a transition from the first hardness to the second hardness is abrupt, and wherein a transition from the second hardness to the third hardness is abrupt.
51. The fastener of claim 48, wherein the nut wherein at least one portion of the nut thread located proximate to the second end is locally softened, and a remaining portion of the nut thread is hardened.
52. The fastener of claim 51, wherein the at least one portion of the nut thread includes a length that is approximately equal to at least a portion of a pitch thread length of the nut thread.
53. The fastener of claim 51, wherein the at least one portion of the nut thread includes a length that is approximately equal to one pitch thread length of the nut thread.
54. The fastener of claim 51, wherein the at least one portion of the nut thread includes a length that is approximately equal to a plurality of pitch thread lengths of the nut thread.
55. The fastener of claim 51, wherein the at least one portion of the nut thread includes a length that is within a range between one pitch thread length of the nut thread and two pitch thread lengths of the nut thread.
Type: Application
Filed: Nov 25, 2014
Publication Date: May 28, 2015
Applicant: ALCOA INC. (Pittsburgh, PA)
Inventors: Donald C. Busby (Woodway, TX), Richard Franklin (Hewitt, TX), James L. Wollard (Waco, TX)
Application Number: 14/553,476
International Classification: F16B 39/30 (20060101); F16B 37/00 (20060101);