Patent US3763909A successfully refreshed from Google Patents.
US3763909A
Expired / Lapsed
US
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Self-locking bolt
Assignee: ROCKFORD PRODUCTS ACQUISITION Corp A CORP OF ILLINOIS
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Filing: 1971-06-02
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Granted: 1973-10-09
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Expires: 1991-06-02
Abstract
Abstract A thread is rolled on the bolt blank around a predetermined length thereof, and during the thread-rolling operation the bolt is indented at diametrically opposed parts of its threaded length, to give a portion of this length a generally elliptical cross-section which is near but spaced from the leading end of the bolt. The indented portion surrounds a central axial bore which opens through the leading end of the bolt, the bore diameter being 0.35D to 0.50D and the bore length being about 1D, where D is the nominal outer diameter of the thread on the bolt. The pitch diameter of the thread on the major axis of the elliptical cross-section is slightly greater than the normal pitch diameter above the elliptical section, such as about 1.03 times the normal pitch diameter, to provide the self-locking action. Thus the friction which causes the self-locking action occurs along the flanks of the threads, rather than at the crests and roots.
Inventors
- 👤 J Stover
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 12:24
CPC Classifications
B; B21; B21H; B21H3/00; B21H3/02; B21H3/025; F; F16; F16B; F16B39/00; F16B39/22; F16B39/28; F16B39/284; Y; Y10; Y10S; Y10S411/00; Y10S411/924; Y10S411/929
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
190 words
A self-locking bolt comprising a shank having a leading end and a thread spiralling around a predetermined length of the shank from said end, the shank being provided with a central axial bore opening through said end and having a length of about 1D, where D is the nominal outer diameter of the threaded bolt, the diameter of said bore being from 0.35D to 0.5D, the bore extending through only a minor part of said threaded length, said minor part having a permanently distorted integral portion forming a pair of diametrically opposed indentations and a pair of diametrically opposed protrusions between said indentations, the protrusions and indentations being spaced from the opposite ends of said minor part and forming a generally elliptical crosssection in which the pitch diameter of the thread on the major axis of the ellipse is greater than the nominal pitch diameter, said bore forming a free space to allow unrestricted movement of the side wall of the bore radially inward along said major axis, the crest diameter of said thread on the major axis of the ellipse being not in excess of the nominal bolt diameter.
Claim 2
Dependent Claim
190 words
A self-locking bolt comprising a shank having a leading end and a thread spiralling around a predetermined length of the shank from said end, the shank being provided with a central axial bore opening through said end and having a length of about 1D, where D is the nominal outer diameter of the threaded bolt, the diameter of said bore being from 0.35D to 0.5D, the bore extending through only a minor part of said threaded length, said minor part having a permanently distorted integral portion forming a pair of diametrically opposed indentations and a pair of diametrically opposed protrusions between said indentations, the protrusions and indentations being spaced from the opposite ends of said minor part and forming a generally elliptical crosssection in which the pitch diameter of the thread on the major axis of the ellipse is greater than the nominal pitch diameter, said bore forming a free space to allow unrestricted movement of the side wall of the bore radially inward along said major axis, the crest diameter of said thread on the major axis of the ellipse being not in excess of the nominal bolt diameter.
Claim 3
Dependent Claim
133 words
A self-locking bolt comprising a shank having a leading end and a thread spiralling around a predetermined length of the shank from said end, the shank being provided with a central axial bore opening through said end and extending through only part of said threaded length, said length part having a pair of diametrically opposed indentations and a pair of diametrically opposed protrusions between said indentations, the protrusions and indentations being spaced from the opposite ends of said length part and forming a generally elliptical cross-section in which the pitch diameter of the thread on the major axis of the ellipse is greater than the nominal pitch diameter of the bolt, the crest diameter of said thread on the major axis of the ellipse being not in excess of the nominal bolt diameter.
Claim 4
Dependent Claim
133 words
A self-locking bolt comprising a shank having a leading end and a thread spiralling around a predetermined length of the shank from said end, the shank being provided with a central axial bore opening through said end and extending through only part of said threaded length, said length part having a pair of diametrically opposed indentations and a pair of diametrically opposed protrusions between said indentations, the protrusions and indentations being spaced from the opposite ends of said length part and forming a generally elliptical cross-section in which the pitch diameter of the thread on the major axis of the ellipse is greater than the nominal pitch diameter of the bolt, the crest diameter of said thread on the major axis of the ellipse being not in excess of the nominal bolt diameter.
Claim 5
Dependent Claim
24 words
A self-locking bolt according to claim 2, in which said elliptical cross-section is confined to about one-half of said part of the threaded length.
Claim 6
Dependent Claim
30 words
A self-locking bolt according to claim 3, in which said elliptical cross-section is located nearer to the inner end of said bore than to the outer end of the bore.
Claim 7
Dependent Claim
56 words
A self-locking bolt according to claim 2, in which said pitch diameter of the thread on the major axis of the ellipse is sufficient to provide the bolt with a prevailing torque of 115 X (D)2.4 as a minimum and 820 X (D)2.5 as a maximum in a mating tapped hole of UNC-2B to UNF-2B dimensions.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-10-08 | 1977-04-09 | 1977-10-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-10-08 | 1981-04-09 | 1981-10-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-10-08 | 1985-04-09 | 1985-10-09 | $7700.00 | Window Closed / Lapsed |