Screw fastener

Claim 1

A screw grommet, comprising: a flange having a screw insertion hole; and a sack-like body integral with said flange and adapted to be inserted through a hole defined within an object to be fastened, said sack-like body having an internal axial screw guide channel communicating with said screw insertion hole defined within said flange for receiving and guiding a screw inserted into said screw insertion hole of said flange, and further having a plurality of axially extending hill-like portions formed upon outer peripheral portions thereof and axially spaced from said flange so as to form slit-like gaps between upper transverse, radially extending ends of each hill-like portion and a lower surface of said flange, said screw grommet being used to fasten said object by inserting said sack-like body through said hole formed within said object such that said object is in contact with said lower surface of said flange while inner sidewall portions of said hole defined within said object are in contact with said hill-like portions of said sack-like body so as to be disposed radially outwardly of said transverse ends of said hill-like portions of said sack-like body as well as said slit-like gaps, inserting said screw through said screw insertion hole of said flange and into said screw guide channel of said sack-like body, and then rotating said screw so as to cause advancement of said screw within said screw guide channel while tapping inner wall surface portions of said screw guide channel by means of a thread formed upon the outer periphery of said screw, whereby said hill-like portions of said sack-like body are expanded radially outwardly with respect to each other, and with increased flexibility as permitted by said slit-like gaps, such that other surfaces of said hill-like portions can engage lower surface portions of said object and thereby fixedly secure said object between said radially expanded hill-like portions of said sack-like body and said flange.