US3878759A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Bi-lobular self-thread forming fastener
Assignee: Textron Inc
•
Filing: 1972-12-29
•
Granted: 1975-04-22
•
Expires: 1992-12-29
Abstract
Abstract There is disclosed a novel self-thread forming fastener having a threaded shank portion, which includes a holding section having a straight thread of generally circular cross section, and a thread forming section including an underdeveloped thread formation providing a bi-lobular thread cross section symmetrically disposed with respect to the axis of the fastener. The thread forming section includes several thread turns disposed on a taper, with the bi-lobular thread merging with the circular thread formation of the holding section. The thread formation of the holding section has a radial height which is at least as great, or greater than, the maximum radial height of the bilobular thread formation on the forming section. Accordingly upon engagement of the holding section with a female thread formed by the forming section, flank to flank interference will be obtained to provide a locking action. Also disclosed is a novel method for fabricating the above-discussed fastener.
Inventors
- 👤 Raymond H Carlson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 03:40
CPC Classifications
B; B21; B21H; B21H3/00; B21H3/02; B21H3/027; F; F16; F16B; F16B25/00; F16B25/001; F16B25/0021; F16B25/0036; F16B25/0042; F16B25/0047; F16B25/0057; Y; Y10; Y10S; Y10S411/00; Y10S411/924; Y10S411/929; Y10S411/938
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
328 words
A self-thread forming fastener for forming a female thread in a pilot aperture and effecting a locking action with said female thread, said fastener comprising: a driving head and a shank having a cold rolled threaded portion, said threaded portion of the shank including a thread-forming section, and a holding section, said thread-forming section having a plurality of helically disposed thread turns formed thereon, each said thread turn being defined by a generally circular root, a pair of helically disposed spaced flank surfaces which are disposed at an acute angle to each other converging in a radially outward direction, and a helically disposed crest surface, the height of said crest surface as measured from the root of said thread varying about the helix of each turn such that said flank surfaces and said crest surfaces define a pair of diametrically opposed arcuate lobe portions and a corresponding pair of diametrically opposed arcuate side portions for each thread turn, the height of the crest surface for said side portions being less than that at said lobe portions, said angle of convergence remaining substantially constant about said thread turn, and said side portions and lobe portions merging smoothly such that said flank surfaces and crest surfaces for each thread turn are continuous and uninterrupted, thereby providing each said thread turn with a truncated profile in section throughout the entire thread turn, and further providing said forming section with a bi-lobular thread formation capable of forming said female thread in the pilot aperture, and said holding section including a plurality of thread turns having a crest formation of a substantially circular configuration, the radial height of said thread turns on the holding section being at least as great as the maximum radial height of the lobe portions on the forming section, such that upon engagement of the thread turns on the holding section the female thread formed by the forming section flank-to-flank engagement will be obtained thereby establishing a locking action.
Claim 2
Dependent Claim
328 words
A self-thread forming fastener for forming a female thread in a pilot aperture and effecting a locking action with said female thread, said fastener comprising: a driving head and a shank having a cold rolled threaded portion, said threaded portion of the shank including a thread-forming section, and a holding section, said thread-forming section having a plurality of helically disposed thread turns formed thereon, each said thread turn being defined by a generally circular root, a pair of helically disposed spaced flank surfaces which are disposed at an acute angle to each other converging in a radially outward direction, and a helically disposed crest surface, the height of said crest surface as measured from the root of said thread varying about the helix of each turn such that said flank surfaces and said crest surfaces define a pair of diametrically opposed arcuate lobe portions and a corresponding pair of diametrically opposed arcuate side portions for each thread turn, the height of the crest surface for said side portions being less than that at said lobe portions, said angle of convergence remaining substantially constant about said thread turn, and said side portions and lobe portions merging smoothly such that said flank surfaces and crest surfaces for each thread turn are continuous and uninterrupted, thereby providing each said thread turn with a truncated profile in section throughout the entire thread turn, and further providing said forming section with a bi-lobular thread formation capable of forming said female thread in the pilot aperture, and said holding section including a plurality of thread turns having a crest formation of a substantially circular configuration, the radial height of said thread turns on the holding section being at least as great as the maximum radial height of the lobe portions on the forming section, such that upon engagement of the thread turns on the holding section the female thread formed by the forming section flank-to-flank engagement will be obtained thereby establishing a locking action.
Claim 3
Dependent Claim
328 words
A self-thread forming fastener for forming a female thread in a pilot aperture and effecting a locking action with said female thread, said fastener comprising: a driving head and a shank having a cold rolled threaded portion, said threaded portion of the shank including a thread-forming section, and a holding section, said thread-forming section having a plurality of helically disposed thread turns formed thereon, each said thread turn being defined by a generally circular root, a pair of helically disposed spaced flank surfaces which are disposed at an acute angle to each other converging in a radially outward direction, and a helically disposed crest surface, the height of said crest surface as measured from the root of said thread varying about the helix of each turn such that said flank surfaces and said crest surfaces define a pair of diametrically opposed arcuate lobe portions and a corresponding pair of diametrically opposed arcuate side portions for each thread turn, the height of the crest surface for said side portions being less than that at said lobe portions, said angle of convergence remaining substantially constant about said thread turn, and said side portions and lobe portions merging smoothly such that said flank surfaces and crest surfaces for each thread turn are continuous and uninterrupted, thereby providing each said thread turn with a truncated profile in section throughout the entire thread turn, and further providing said forming section with a bi-lobular thread formation capable of forming said female thread in the pilot aperture, and said holding section including a plurality of thread turns having a crest formation of a substantially circular configuration, the radial height of said thread turns on the holding section being at least as great as the maximum radial height of the lobe portions on the forming section, such that upon engagement of the thread turns on the holding section the female thread formed by the forming section flank-to-flank engagement will be obtained thereby establishing a locking action.
Claim 4
Dependent Claim
328 words
A self-thread forming fastener for forming a female thread in a pilot aperture and effecting a locking action with said female thread, said fastener comprising: a driving head and a shank having a cold rolled threaded portion, said threaded portion of the shank including a thread-forming section, and a holding section, said thread-forming section having a plurality of helically disposed thread turns formed thereon, each said thread turn being defined by a generally circular root, a pair of helically disposed spaced flank surfaces which are disposed at an acute angle to each other converging in a radially outward direction, and a helically disposed crest surface, the height of said crest surface as measured from the root of said thread varying about the helix of each turn such that said flank surfaces and said crest surfaces define a pair of diametrically opposed arcuate lobe portions and a corresponding pair of diametrically opposed arcuate side portions for each thread turn, the height of the crest surface for said side portions being less than that at said lobe portions, said angle of convergence remaining substantially constant about said thread turn, and said side portions and lobe portions merging smoothly such that said flank surfaces and crest surfaces for each thread turn are continuous and uninterrupted, thereby providing each said thread turn with a truncated profile in section throughout the entire thread turn, and further providing said forming section with a bi-lobular thread formation capable of forming said female thread in the pilot aperture, and said holding section including a plurality of thread turns having a crest formation of a substantially circular configuration, the radial height of said thread turns on the holding section being at least as great as the maximum radial height of the lobe portions on the forming section, such that upon engagement of the thread turns on the holding section the female thread formed by the forming section flank-to-flank engagement will be obtained thereby establishing a locking action.
Claim 5
Dependent Claim
40 words
A fastener as defined in claim 1 wherein a number of the thread turns on said forming section are disposed on a taper, with the radial height of the respective lobe portions increasing in a direction toward the holding section.
References Cited (Backward Citations)
US1676482A
Cited
US3180126A
Cited
US3180202A
Cited
US3246556A
Cited
US3398625A
Cited
US3527136A
Cited
US3633455A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-04-21 | 1978-10-21 | 1979-04-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-04-21 | 1982-10-21 | 1983-04-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-04-21 | 1986-10-21 | 1987-04-22 | $7700.00 | Window Closed / Lapsed |