Importance

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Abstract

A method for fabricating a fastener and washer assembly wherein the washer is permanently retained on the fastener by an annular raised portion on the shank of the fastener. The annular raised portion and the inner diameter of the washer are mutually formed so as to promote elastic deformation of both the raised portion and the washer when the washer is forced over the raised portion to be retained on the fastener. The method allows the fastener and the washer to be fully fabricated and processed prior to assembly, including such desirable steps as heat treating and plating of both the fastener and the washer. The annular raised portion is formed by a pair of converging annular surfaces which define a predetermined diameter. The washer has an inner diameter surface having a pair of chamfered edges. The washer is assembled onto the shank of the fastener by forcing the chamfered edge of the washer against and past the annular raised portion. the inner diameter is sized relative to the diameter of the annular raised portion such that it is elastically, and not plastically, expanded while the annular raised portion is elastically compressed as the washer is forced over the annular raised portion. Thereafter, both the washer and the annular raised portion elastically revert back to their respective diameters. The washer is permanently retained on the fastener by the raised portion to form the fastener and washer assembly.

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First Claim