Fixed and variable locking fixation assembly
First Claim
1. A locking fastener having a proximal end and a distal end terminating in a tip, comprising:
- a) a head disposed at said proximal end having an upper region, a groove adjacent said upper region, and a lower region adjacent said groove;
wherein said upper region has a first diameter at said proximal end and a second diameter adjacent said groove and wherein said lower region has a third diameter adjacent said groove and a fourth diameter at a distal end of said lower region;
b) a shank adjacent said head, wherein said shank further comprises a shoulder adjacent said lower region of said head;
c) a threaded section adjacent said shankd) a locking ring having an outer diameter and an inner diameter and a leading surface having a leading diameter associated therewith and a trailing surface having a trailing diameter associated therewith, wherein said leading surface further comprises a chamfer or fillet, and wherein said locking ring resides within said groove of said head; and
e) wherein said leading diameter is less than said trailing diameter, and said trailing diameter is substantially equal to said outer diameter.
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Accused Products
Abstract
A locking screw assembly is provided which allows installation into a plate-like member using relatively little force, but which requires relatively great force for removal. The fastener has an annular locking ring provided within a groove in the head of the screw to allow the screw to sit within or flush with the anterior surface of the plate. The through-hole in the plate which receives the locking screw comprises an entrance, a collar section, an undercut, and an exit. The locking ring resides within the undercut. The locking ring has a leading surface that is chamfered or radiused and a trailing surface that is flat. The chamfer allows the locking ring to easily be inserted into the through-hole by interacting with a lead chamfer in the entrance. After installation, the flat trailing surface abuts a lip adjoining the collar section and the undercut and prevents the screw from being easily removed from the through-hole.
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Citations
32 Claims
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1. A locking fastener having a proximal end and a distal end terminating in a tip, comprising:
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a) a head disposed at said proximal end having an upper region, a groove adjacent said upper region, and a lower region adjacent said groove;
wherein said upper region has a first diameter at said proximal end and a second diameter adjacent said groove and wherein said lower region has a third diameter adjacent said groove and a fourth diameter at a distal end of said lower region;b) a shank adjacent said head, wherein said shank further comprises a shoulder adjacent said lower region of said head; c) a threaded section adjacent said shank d) a locking ring having an outer diameter and an inner diameter and a leading surface having a leading diameter associated therewith and a trailing surface having a trailing diameter associated therewith, wherein said leading surface further comprises a chamfer or fillet, and wherein said locking ring resides within said groove of said head; and e) wherein said leading diameter is less than said trailing diameter, and said trailing diameter is substantially equal to said outer diameter. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A locking fastener, comprising:
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a screw, wherein said screw comprises a proximal screw head and a threaded section distal of said screw head, said screw head comprising a groove therein, said groove having a groove innermost axial dimension; and a retainer within said groove, said retainer having a retainer maximum axial dimension, wherein said retainer maximum axial dimension is less than said groove innermost axial dimension; and said retainer comprising a leading end having a leading diameter and a trailing end having a trailing diameter, wherein said trailing diameter is greater than said leading diameter. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21)
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22. A locking fastener, comprising:
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a screw, wherein said screw comprises a proximal screw head and a threaded section distal of said screw head, said screw head comprising a groove therein, wherein said groove has a pair of substantially parallel sides; and a retainer at least partially within said groove; and said retainer comprising a leading end having a leading diameter and a trailing end having a trailing diameter, wherein said trailing diameter is greater than said leading diameter. - View Dependent Claims (23, 24, 25, 26)
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27. A locking fastener comprising:
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a screw, wherein said screw comprises a proximal screw head and a threaded section distal of said screw head, said screw head comprising a groove therein; and a retainer at least partially within said groove, wherein said retainer has an edge comprising a flat surface in a portion thereof and comprises a chamfer or rounding adjoining said flat surface. - View Dependent Claims (28, 29, 30, 31)
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32. A locking fastener, comprising:
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a screw, wherein said screw comprises a proximal screw head and a threaded section distal of said screw head, said screw head comprising a groove therein, wherein said groove has two sides that are flat and lie in planes substantially perpendicular to a longitudinal axis of said screw; and a retainer at least partially within said groove; and said retainer comprising a leading end having a leading diameter and a trailing end having a trailing diameter, wherein said trailing diameter is greater than said leading diameter.
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Specification