Plastic screw grommet

Abstract

A one-piece plastic screw grommet for use in mounting a screw relative to a blind bore located in a fibrous material. The grommet includes a shank portion and may have a laterally extending head at one end. The shank has a first diameter portion adjacent the head complementary in size to the bore and connected to a smaller free end portion by a tapered intermediate portion. Annular rings and axially disposed anti-rotation means, each having a radial extent greater than said bore, are carried on the exterior of said shank. A transverse slot extends through the intermediate and first diameter portions and a pair of flexible shouldered arms are disposed within the slots in opposed walls and extend axially toward said head end from their connection to said free end. A non-circular bore extends through the head end and first portion and blends into a cylindrical bore in said free end portion with the interior opposed arm surfaces of said arms having a concave cross section, the concavity having a radius of curvature substantially equal to the free end bore which equals the pitch diameter of the screw to be accepted therein. Each arm includes an interior and exterior taper and carries a flange at its free end for engaging the bore of the fibrous material to prevent inversion of said arms when subjected to pull-out forces.