| 摘要 |
1478951 Rolling threads CHARLES RICHARDS FASTENERS Ltd 15 April 1976 [17 April 1975] 15778/75 Heading B3M [Also in Division F2] A self-locking thread is formed on a bolt or rod by rolling between dies. The thread has at least two portions of different form, one portion being of a standard form, and the other portion being a locking portion with its root and crest axially offset from the standard pitch lines, the offset of the crest being in the same direction as, and greater than, the offset of the root, and the flanks of the locking thread being correspondingly displaced, with the flank 12 on the side of the thread which is moved away from the standard pitch line being outwardly bulged. As shown, four turns of locking thread lead via short transition sections into standard thread portions at the two ends. The standard thread has a pitch P, flank angle A, root radius r 1 , and crest radius r 4 . In the locking portion, the crest is axially offset a distance W and the root a distance X1 which is preferably between 1/3 and 2/3 of W. The leading flank 12 is of arcuate cross-section, with a radius R, and the trailing flank 13 has a flank angle B which is greater than A. The root radius is the same as for the standard thread, and the crest radius r 5 is less than r 4 . The transition sections preferably each extend over 1/12 turn, but may be up to one turn. Various arrangements of locking and standard turns are possible, e.g. alternate portions of two locking turns and one standard turn.
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