Claims
- 1. A thread-forming fastener having a shank portion with a continuous helical roll-threaded formation of uniform pitch, the crest of said thread defining a helix including in a plurality of turns of the thread arcuate regions merging gradually with intermediate arcuate lobes, said lobes having radii of curvature that are less than the radii of curvature of the arcuate regions, said thread having a depth that is at a minimum circumferentially midway between said lobes, said thread having a depth that is at a maximum at said lobes, and a lobe in one turn of the thread being circumferentially offset from the nearest lobe in an adjacent turn and in which said offset is one-half the circumferential spacing of two adjacent lobes.
- 2. A thread-forming fastener according to claim 1 in which the thread root is of constant width over a number of turns.
- 3. A thread-forming fastener according to claim 1 in which said thread root is of constant diameter.
- 4. A thread-forming fastener according to claim 1 in which the circumferential spacing between adjacent lobes is substantially 240.degree. and the circumferential spacing of a lobe from an adjacent region of minimum thread depth is substantially 120.degree..
- 5. A thread-forming fastener according to claim 1 in which there are lobes that are aligned substantially parallel to the central axis of the shank portion, the nearest of two aligned lobes being 720.degree. apart.
- 6. A thread-forming fastener having a shank portion with a continuous helical roll-threaded formation of uniform pitch, the crest of said thread defining a helix including in a plurality of turns of the thread arcuate regions merging gradually with intermediate arcuate lobes, said lobes having radii of curvature that are less than the radii of curvature of the arcuate regions, said thread having a depth that is at a minimum circumferentially midway between said lobes, said thread having a depth that is at a maximum at said lobes, and a lobe in one turn of the thread being circumferentially offset from the nearest lobe in an adjacent turn, there being lobes that are aligned substantially parallel to the central axis of the shank portion, the nearest of two aligned holes being substantially 720 degrees apart.
- 7. A thread-forming fastener having a shank portion with a continuous helical roll-threaded formation of uniform pitch, the crest of said thread defining a helix including in a plurality of turns of the thread arcuate regions merging gradually with intermediate arcuate lobes, said lobes having radii of curvature that are less than the radii of curvature of the arcuate regions, said thread having a depth that is at a minimum circumferentially midway between said lobes, said thread having a depth that is at a maximum at said lobes, and a lobe in one turn of the thread being circumferentially offset from the nearest lobe in an adjacent turn, and in which the circumferential spacing between adjacent lobes is substantially 240 degrees and the circumferential spacing of a lobe from an adjacent region of minimum thread depth is substantially 120 degrees.
Parent Case Info
This application is a division of application Ser. No. 229,450, filed Jan. 29, 1981, now U.S. Pat. No. 4,353,233.
US Referenced Citations (13)
Foreign Referenced Citations (1)
Number |
Date |
Country |
4149 OF |
Jan 1907 |
GBX |
Divisions (1)
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Number |
Date |
Country |
Parent |
229450 |
Jan 1981 |
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