Molded plastic fastener

Claim 1

A fastener for securing together elements having aperture means formed therein comprising an integral structure molded of a resilient material, said integral structure including a head part operable to engage one of said elements when said integral structure is disposed in an operative position in relation to said elements, a shank part having a first portion extending from said head part operable to engage within the aperture means when said integral structure is disposed in said operative position and a second free end portion extending from said first shank portion operable to extend beyond said aperture means when said integral structure is disposed in said operative position, said first shank portion having diametrically opposed aperture engaging surfaces of relatively small width with respect to the size of said aperture means, said second shank portion having guide surfaces of relatively small width extending from the free end thereof outwardly in opposite direction and toward the aperture engaging surfaces of said first shank portion, said shank part extending continuously between said aperture engaging surfaces throughout the longitudinal extent thereof, and a pair of locking parts disposed on opposite sides of said shank part, each of said locking parts having a first portion formed with an end thereof integral with said head part and extending therefrom in spaced coextensive relation to said first shank portion and a second portion extending from said first locking portion in spaced coextensive relation to said second shank portion and being integrally joined at its end with the adjacent free end of said second shank portion, said locking parts having outwardly facing aperture engaging surfaces formed in the first portions thereof, locking surfaces extending outwardly from said aperture engaging surfaces for engaging another element adjacent said aperture means when said integral structure is in said operative position, and cam surface means extending from said locking surfaces and converging adjacent the free end of said shank part operable in response to the movement of said integral structure into said operative position to engage the aperture means at opposed portions angularly spaced from the opposed portions engaged by said shank part guide surfaces to cause said locking parts to progressively flex both with a tortional movement about their integral end connections and with an inward bending movement between their integral end connections so that said flexure will cause said locking parts to move outwardly when said integral structure reaches said operative position permitting said locking surfaces to engage the other element adjacent said aperture means and thereby secure said elements together, said cam surface means on each locking part including two portions, one of which faces in a direction substantially radially outwardly with respect to the longitudinal axis of said integral structure and the other of which faces in a direction generally at an angle of approximately 45* with respect to the radially outward direction in which said one portion faces.