US3683437A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of making a self-thread forming fastener with easy thread pickup
Assignee: Individual
•
Filing: 1971-08-26
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Granted: 1972-08-15
•
Expires: 1991-08-26
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
2026-11-03 12:35
CPC Classifications
B; B21; B21H; B21H3/00; B21H3/02; B21H3/027
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
302 words
A method of making a self-thread forming screw for forming threads in a pilot hole in a workpiece, comprising: forming a blank having a work-entering end portion of circular cross section of smaller diameter than the diameter of said pilot hole, a shank portion of larger pitch surface cross section than said work-entering end portion, and an intermediate cylindrical portion of circular cross section between said shank portion and said work-entering end portion, said intermediate cylindrical portion having a length equal to at least one full thread turn and a diameter intermediate that of said shank portion and said work-entering end portion, and other blank portions tapering conically inwardly from said intermediate portion to said work-entering end portion and outwardly from said intermediate pOrtion to said shank portion; and rolling on a centerless basis a continuous thread formation on said blank; and during said rolling operation forming a thread on said shank portion and on said work-entering end and intermediate cylindrical portions which thread increases in radial height from a beginning height at said work-entering end less than the radius of said pilot hole to its full height on said shank portion in three stages; in the first stage the crest of said thread increasing rapidly in radial height within a small circumferential angle, less than one-half a thread revolution, to a thread height capable of establishing substantial initial thread-forming engagement with the sidewall of said pilot hole; in the second stage the crest of said thread continuing on said intermediate cylindrical portion for at least one full thread turn at substantially the same radial height as it achieves in said first stage; in the third stage the crest of said thread increasing in radial height substantially to the maximum radial height of the crest of said thread on said shank portion.
Claim 2
Independent Claim
302 words
A method of making a self-thread forming screw for forming threads in a pilot hole in a workpiece, comprising: forming a blank having a work-entering end portion of circular cross section of smaller diameter than the diameter of said pilot hole, a shank portion of larger pitch surface cross section than said work-entering end portion, and an intermediate cylindrical portion of circular cross section between said shank portion and said work-entering end portion, said intermediate cylindrical portion having a length equal to at least one full thread turn and a diameter intermediate that of said shank portion and said work-entering end portion, and other blank portions tapering conically inwardly from said intermediate portion to said work-entering end portion and outwardly from said intermediate pOrtion to said shank portion; and rolling on a centerless basis a continuous thread formation on said blank; and during said rolling operation forming a thread on said shank portion and on said work-entering end and intermediate cylindrical portions which thread increases in radial height from a beginning height at said work-entering end less than the radius of said pilot hole to its full height on said shank portion in three stages; in the first stage the crest of said thread increasing rapidly in radial height within a small circumferential angle, less than one-half a thread revolution, to a thread height capable of establishing substantial initial thread-forming engagement with the sidewall of said pilot hole; in the second stage the crest of said thread continuing on said intermediate cylindrical portion for at least one full thread turn at substantially the same radial height as it achieves in said first stage; in the third stage the crest of said thread increasing in radial height substantially to the maximum radial height of the crest of said thread on said shank portion.
References Cited (Backward Citations)
US2113600A
Cited
US3246556A
Cited
US3342234A
Cited
US3520343A
Cited
US3426820A
Cited
US3626733A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-08-15 | 1976-02-14 | 1976-08-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-08-15 | 1980-02-14 | 1980-08-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-08-15 | 1984-02-14 | 1984-08-15 | $7700.00 | Window Closed / Lapsed |