US3877339A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Lobular screw with means for improved stress distribution
Assignee: Research Engineering and Manufacturing Inc
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Filing: 1973-12-07
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Granted: 1975-04-15
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Expires: 1993-12-07
Abstract
Abstract A screw, such as a self-tapping screw, comprises a threaded shank with a lobular cross-section and adapted for engagement with a mating thread of circular cross section. At the head end of the screw there is a bearing surface for pressure engagement against a member to be retained by the screw. This bearing surface has alternately arranged, circumferentially disposed recesses and ridges and with the recesses being in line with the lobes. Upon tightening of the screw at high torques the ridges engage the member to be retained and the recesses cause relief from stress concentrations at the lobes by permitting axial movement of the screw so as to increase the pressure flank areas of engagement of the screw and the mating thread. A more positive locking engagement of the thread is also provided. The bearing surface may be integral with the screw head or may be provided on a washer on the screw.
Inventors
- 👤 Herman G Muenchinger
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 16:34
CPC Classifications
F; F16; F16B; F16B39/00; F16B39/22; F16B39/24; Y; Y10; Y10S; Y10S411/00; Y10S411/955; Y10S411/956; Y10S411/957; Y10S411/96
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
174 words
A screw comprising a head end and a thread shank extending axailly from said head end, the thread on said shank having a number of circumferentially spaced lobes and intermediate sides which recede from the lobes such that the normal engagement of said screw thread with a mating thread of circular cross-section is substantially localized at said lobes as the screw is driven into the mating thread, and means at said head end forming an axially presented surface for bearing against a member to be retained by said screw, said bearing surface having circumferentially spaced recesses presented toward said shank and with the recesses being substantially aligned with said lobes, and said bearing surface also having ridges circumferentially intermediate said recesses and shaped such that tightening of the screw causes said ridges to engage said member to be retained and impose pressure thereon and said recesses provide relief to permit axial movement of the screw upon further tightening to increase the areas of pressure flank engagement of the screw thread with the mating thread.
Claim 2
Dependent Claim
174 words
A screw comprising a head end and a thread shank extending axailly from said head end, the thread on said shank having a number of circumferentially spaced lobes and intermediate sides which recede from the lobes such that the normal engagement of said screw thread with a mating thread of circular cross-section is substantially localized at said lobes as the screw is driven into the mating thread, and means at said head end forming an axially presented surface for bearing against a member to be retained by said screw, said bearing surface having circumferentially spaced recesses presented toward said shank and with the recesses being substantially aligned with said lobes, and said bearing surface also having ridges circumferentially intermediate said recesses and shaped such that tightening of the screw causes said ridges to engage said member to be retained and impose pressure thereon and said recesses provide relief to permit axial movement of the screw upon further tightening to increase the areas of pressure flank engagement of the screw thread with the mating thread.
Claim 3
Dependent Claim
31 words
A screw according to claim 1 in which said bearing surface is on a head at said head end and is of an undulating shape to define said recesses and ridges.
Claim 4
Dependent Claim
19 words
A screw according to claim 2 in which said bearing surface is on a resilient flange on said head.
Claim 5
Dependent Claim
19 words
A screw according to claim 3 in which said flange is formed with a groove to enhance its resiliency.
Claim 6
Dependent Claim
68 words
A screw according to claim 1 in which said bearing surface is on a washer that is axailly intermediate a head at said head end and at least part of said screw thread, said washer being rotatable relative to said head and shank, and cooperating means on the head and washer for aligning said recesses with said lobes upon tightening said screw against said member to be retained.
Claim 7
Dependent Claim
31 words
A screw according to claim 5 in which said ridges are formed by teeth on said washer and said recesses are formed by portions of the washer circumferentially intermediate said teeth.
Claim 8
Dependent Claim
17 words
A screw according to claim 1 which is a screw having means for forming the mating thread.
Claim 9
Dependent Claim
55 words
A screw according to claim 1 in which the axial distance between high regions of the ridges and low regions of the recesses is at least substantially the axial clearance between the pressure flanks of the screw thread and the mating thread at said sides when the said high regions engage said member to retained.
Claim 10
Dependent Claim
69 words
A screw according to claim 1 in which said bearing surface is on a washer that is on said shank at said head end, and there are cooperating means on said washer and on a part of said screw for orienting the washer such that the recesses are respectively aligned with said lobes and the washer is turned by the screw as the latter is driven into the workpiece.
Claim 11
Dependent Claim
20 words
A screw according to claim 9 in which said washer is of undulating shape to define said ridges and recesses.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-04-14 | 1978-10-14 | 1979-04-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-04-14 | 1982-10-14 | 1983-04-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-04-14 | 1986-10-14 | 1987-04-15 | $7700.00 | Window Closed / Lapsed |