Threaded locking fastener

Claim 1

Claims 1. A threaded fastener comprising thread 105 means, a load surface, and wrenching means permitting said fastener to be tightened and loosened, said load surface being adapted to be tightened against a substantially flat mating surface and providing self-locking means 110 including: (a) a plurality of bearing surfaces symmetrically positioned around said thread means and contained in a bearing plane, each bearing surface providing a narrow end in the direction of 115 tightening rotation, a wider end in the direction of ■ loosening rotation and an inner side edge joining the inner extremities of said ends; (b) an inclined ramp surface extending inwardly from each of said inner side edges and back from 120 said bearing plane; (c) radially and axially extending shoulders joining said wider end of said bearing surfaces and the adjacent end of said ramp surfaces, the height of said shoulders increasing in a radially 125 inward direction; (d) said ramp surfaces and associated shoulders cooperating to define recesses symmetrically arranged around said thread means, tightening of said fastener against a 4 GB 2 024 979 A 4 mating surface causing said bearing surfaces to be pressed into said mating surface and causing the material forming said mating surface to be displaced past said bearing plane into said 5 recesses adjacent to said shouldersvso that a mechanical interference is established between said shoulders, and the material of said mating surface displaced past said bearing plane to resist loosening of said fasteners, said ramp surfaces 10 engaging the material displaced past said bearing plane while said fastener is being tightened and operating to provide a camming action allowing continued tightening of said fastener without encountering excessive torque. 15 2. A threaded fastener as set forth in claim 1 wherein said bearing surfaces are generally triangular in shape positioned with apexes at said narrow ends and bases at said wider ends. 3. A threaded fastener as set forth in claim 2 20 wherein said bearing surfaces provide outer side edges which cooperate to provide a substantial portion of the periphery of said self-locking means, and said periphery is a circle coaxial with said thread means. 25 4. A threaded fastener as set forth in claim 3 wherein the apices of said bearing surfaces are spaced from the base of the next adjacent bearing surface. 5. A threaded fastener as set forth in claim 3 30 wherein said load surface is provided with an annular recess around said thread means, and said shoulders and ramp surfaces extend radially inward to and terminate at said annular recess. - 6. A.threaded fastener as set forth in claim 5 35 wherein said annular recess is radially spaced from said thread means, said load face being axially spaced back from said bearing plane between said annular recess and said thread means by an amount necessary to normally 40 prevent contact with said mating surface at least until clamping load is reached. 7. A threaded fastener as set forth in claim 1 wherein said bearing surfaces cooperate to provide a continuous bearing surface around said 45 thread means. 8. A threaded fastener as set forth in claim 7 wherein said bearing surfaces provide outer side edges which cooperate to provide a periphery of said self-locking means, and said periphery is a 50 circle coaxial with said thread means. 9. A threaded fastener as set forth in claim 1 •wherein said threaded fastener is a nut. 10. A threaded fastener as set forth in claim 1 wherein said thread fastener is a bolt or screw. 11 . A threaded fastener as set forth in claim 1 wherein said ramp surfaces and said bearing plane define a radial angle of about 6 degrees. 12. A threaded fastener as set forth in claim 1 wherein said ramp surfaces and said bearing plane define a peripheral angle of about 5 degrees. 13. A threaded fastener as set forth in claim 12 wherein said ramp surfaces and said bearing plane define a radial angle of about 6 degrees. 14. A threaded fastener comprising thread means, a load surface, and wrenching means permitting such fastener to be tightened and loosened, said load surface being adapted to be tightened against a substantially flat mating surface, said load surface providing a plurality of substantially triangular bearing surfaces contained substantially in a single bearing plane, said bearing surfaces providing apices in the direction of tightening rotation, substantially radial bases in the direction of loosening rotation and inner side edges, said load surfaces providing inclined intermediate ramp surfaces intersecting said side edges and inclined inwardly and back from said bearing plane to an edge joined to the associated base by an axially extending shoulder, each ramp surface and associated shoulder cooperating to define a recessed zone spaced back from said bearing plane, said bearing surfaces on tightening pressing into the flat mating surface causing the material forming said mating surfaces to be displaced past said bearing plane into the said recessed zones adjacent to said shoulders so that a mechanical interference is established between said shoulders and the material of said mating surface displaced past said bearing plane to resist loosening of said fastener. 15. A threaded fastener as set forth in claim 14 wherein said apices of said bearing surfaces are spaced from the base of an adjacent bearing surface. . 16. A threaded fastener as set forth in claim 15 wherein the outer extremity of said bearing surfaces are portions of a circle substantial coaxial with said thread means. 17. A threaded fastener substantially as hereinbefore described with reference to the accompanying drawings. 55 60 65 70 75 80 85 90 95 100 Printedfor Her Majesty's Stationery Office by the Courier Press, Leamington Spa, 1980. Published by the Patent Office, 25 Southampton Buildings, London, WC2A 1 AY, from which copies maybe obtained.