Self-locking screw threads
AssigneeCharles Richards Fasteners Limited
InventorRichard Charles Goldby
Life of this patent
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Abstract
A screw threaded member having a thread with at least two portions of different form, one portion being of standard form and the other portion, a locking portion, having its root and crest offset from the standard lead, the offset of the crest being in the same direction as and greater than the offset of the root, the flanks of the locking thread being correspondingly displaced and the flank on the side of the thread which is displaced away from the standard pitch line being bulged outwardly. The root offset may be between one third and two thirds of the offset of the crest. The offsets may be in either direction but are preferably in that direction which moves the lead flank away from the standard pitch line.
Claims10
A screw threaded member having a first portion of thread of a standard form having constant profile, pitch, root diameter and crest diameter, and a second portion of thread of a locking form continuous with said standard portion of thread and having said constant root diameter and constant crest diameter but having a root lead offset from the standard root lead, a crest lead offset from the standard crest lead, the crest offset being greater than the root offset, the flanks of said locking form of thread being displaced from the position of the flanks of thread of said standard form by an amount corresponding to said root and crest lead offsets, a first of the displaced flanks being bulged outwardly, the bulging being greatest in a central region of the flank and decreasing continuously towards the crest and towards the root thereof, the second of the displaced flanks being offset in the direction of said bulged flank.
Dependencies are inferred from the claim text.