US3633455A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Self-thread-forming fastener with easy thread pickup
Assignee: Textron Inc
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Filing: 1970-02-13
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Granted: 1972-01-11
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Expires: 1990-02-13
Abstract
Abstract The work-entering end of a self-thread-forming fastener is provided with a step-tapered portion for initially engaging the sidewall of the pilot hole of a workpiece. The invention is characterized by the fact that the tapered portion is of substantially circular cross section while the radial height of the thread over such step-tapered portion increases from a beginning height less than the diameter of the pilot hole to the full height of the thread on the shank portion in stages. In the first such stage, the crest of the thread increases rapidly in radial height within a small circumferential angle to establish substantial initial thread-forming engagement with the pilot hole. In the second stage, the crest of the thread continues for at least one full thread turn at substantially the same radial height as it achieves in the first stage to insure thread pickup with minimum end loading. In the third stage, the crest of the thread increases in radial height substantially to the maximum radial height of the crest of the thread on the shank portion.
Inventors
- 👤 Eugene R Larson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 18:00
CPC Classifications
F; F16; F16B; F16B25/00; F16B25/0036; F16B25/0042; F16B25/0047; F16B25/0057; F16B25/0078
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
205 words
A self-thread-forming fastener for forming threads in a pilot hole in a workpiece and having a pilot end of circular cross section of smaller diameter than said pilot hole, a threaded shank portion of larger pitch surface cross section than said pilot end and a step-tapered thread-forming portion of circular cross section intermediate said pilot end and said shank portion, a. the crest of the thread over said step-tapered portion increasing in radial height from a beginning height at said pilot end less than the radius of said pilot hole to its full height in said shank portion in three stages; b. in the first stage the crest of the thread increasing rapidly in radial height within a small circumferential angle, less than one-half a thread revolution, to establish substantial initial thread-forming engagement with the sidewall of said pilot hole in said workpiece; c. in the second stage the crest of the thread continuing for at least one full thread turn at substantially the same radial height as it achieves in said first stage; and d. in the third stage the crest of the thread increasing in radial height substantially to the maximum radial height of the crest of the thread on said shank portion.
Claim 2
Dependent Claim
205 words
A self-thread-forming fastener for forming threads in a pilot hole in a workpiece and having a pilot end of circular cross section of smaller diameter than said pilot hole, a threaded shank portion of larger pitch surface cross section than said pilot end and a step-tapered thread-forming portion of circular cross section intermediate said pilot end and said shank portion, a. the crest of the thread over said step-tapered portion increasing in radial height from a beginning height at said pilot end less than the radius of said pilot hole to its full height in said shank portion in three stages; b. in the first stage the crest of the thread increasing rapidly in radial height within a small circumferential angle, less than one-half a thread revolution, to establish substantial initial thread-forming engagement with the sidewall of said pilot hole in said workpiece; c. in the second stage the crest of the thread continuing for at least one full thread turn at substantially the same radial height as it achieves in said first stage; and d. in the third stage the crest of the thread increasing in radial height substantially to the maximum radial height of the crest of the thread on said shank portion.
Claim 3
Dependent Claim
55 words
A self-thread-forming fastener as in claim 1 in which said shank portion has an arcuate triangular pitch surface cross section and said rapidly increasing radial height of said crest of said thread in said first stage occurs at a point on said step-tapered portion in line with an intermediate low area on said shank portion.
Claim 4
Dependent Claim
26 words
A self-thread-forming fastener as in claim 2 in which said crest of said thread in said first stage increases rapidly in radial height in approximately 60*.
Claim 5
Dependent Claim
31 words
A self-thread-forming fastener as in claim 1 in which said crest of said thread continues in said second stage at a substantially constant radial height for approximately 1 1/3 thread turns.
Claim 6
Dependent Claim
175 words
A self-thread-forming fastener for forming threads in a pilot hole in a workpiece, said fastener having a tapered work-entering end portion and a shank portion, the shank portion being provided with a thread of arcuate triangular pitch surface cross section, the thread continuing from said shank portion onto said work-entering end portion, the invention being characterized by: a. the thread turn on said tapered portion which is adapted for initially engaging the sidewall of the pilot hole in the workpiece having a crest of substantially circular cross section and a radial dimension greater than the radius of said pilot hole by an amount equal to approximately 20 to 30 percent of the height of the thread on said shank portion; b. said first-mentioned thread continuing at the aforesaid radial dimension for at least one full thread turn; and c. said thread on said tapered portion following said one full thread turn changing gradually from said substantially circular cross section configuration to an arcuate triangular configuration whence it merges with said thread on said shank portion.
Claim 7
Dependent Claim
175 words
A self-thread-forming fastener for forming threads in a pilot hole in a workpiece, said fastener having a tapered work-entering end portion and a shank portion, the shank portion being provided with a thread of arcuate triangular pitch surface cross section, the thread continuing from said shank portion onto said work-entering end portion, the invention being characterized by: a. the thread turn on said tapered portion which is adapted for initially engaging the sidewall of the pilot hole in the workpiece having a crest of substantially circular cross section and a radial dimension greater than the radius of said pilot hole by an amount equal to approximately 20 to 30 percent of the height of the thread on said shank portion; b. said first-mentioned thread continuing at the aforesaid radial dimension for at least one full thread turn; and c. said thread on said tapered portion following said one full thread turn changing gradually from said substantially circular cross section configuration to an arcuate triangular configuration whence it merges with said thread on said shank portion.
References Cited (Backward Citations)
US3246556A
Cited
US3520343A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-01-10 | 1975-07-12 | 1976-01-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-01-10 | 1979-07-12 | 1980-01-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-01-10 | 1983-07-12 | 1984-01-11 | $7700.00 | Window Closed / Lapsed |