Grommet type fastener

Claim 1

A one piece plastic anchor member for application to an apertured workpiece in combination with a threaded shank of a screw member, said anchor member including a head section providing a surface for clampingly engaging one side of a workpiece, and a shank section extending axially from said head section, said shank section including an elongate hollow portion for accommodating a screw shank, the trailing extremity of which is laterally yieldable, and diametrically disposed peripherally positioned shank arms integrally connected with and extending axially between the entering extremity of said hollow portion and the underside of the head section, the inner surfaces of said arms being normally disposed outwardly from the external periphery of the trailing extremity of said hollow screw accommodating portion leaving spaces therebetween, work engaging peripheral shoulder means associated with said arms and spaced axially from the underside of said head section, said shank arms being readily collapsible into the spaces between the arms and the screw accommodating portion to permit insertion of said shank section within a complementary work aperture, said trailing extremity of said hollow portion presenting walls which are laterally expandable into the spaces therebetween and said arms and which define a minimum internal diameter less than the maximum diameter of the screw shank for lateral expansion thereof upon insertion of the screw shank with the lateral extent of each of the spaces being not greater than one-half the difference between said minimum internal diameter of said walls and said maximum diameter of said screw shank, whereby the walls are urged into abutment with the inner surfaces of said arms as an incident to the application of a screw member to said trailing extremity.