Patent ID: 8585336

Claim:
A fastener, comprising: a bolt comprising a head, a threaded engaging portion, a shaft portion between the head and the threaded engaging portion, a bottom flange extending radially and outwards from an end of the shaft portion connecting the threaded engaging portion, and a protruding flange extending radially and outwards from the shaft portion and near the head, the shaft portion comprising a main part connecting the head, a tail part connecting the bottom flange, and a guiding part connecting the main part and the tail part, a diameter of tail part being smaller than a diameter of the main part, diameters of the guiding part increasing from the tail part to the main part along an axial direction of the bolt; a ring engaged around the bolt; and a coil spring coiling the shaft portion and sandwiched between the head of the bolt and the ring, an end of the coil spring abutting the protruding flange.