Two-piece expandable plastic rivet

Claim 1

A plastic rivet consisting of rivet body comprised of a flanged head and a leg member extending from the bottom of the head and having a tip remote from said head, the rivet body having an axial hole extending through its entire length, and a rotationally asymmetric pin which when inserted into the through-hole of the rivet body expands the leg member, characterized in that the through-hole has a large-diameter portion extending from the head of the rivet body to an intermediate portion of the leg member, a shoulder being formed between the large-diameter portion and the remainder of the through-hole, the leg member being formed to have a single movable leg by providing two off-center slits opening axially outwardly at said tip and running axially inward from the tip of the leg member, said slits communicating with the through-hole, the movable leg being provided on its inner surface with a tooth-like protuberance extending transversely substantially completely across said through-hole, the pin having a shank portion having a transverse dimension and being provided on one end with a head capable of entering the large-diameter portion of the through-hole, the shank of the pin being provided with two V-shaped recesses spaced in the axial direction of the pin and each having a depth substantially equal to said transverse dimension of said pin to leave a tooth-like protuberance therebetween having a height substantially at least as great as said transverse dimension of said pin, and the tip of the tooth-like protuberance of the pin being provided with a shallow notch, whereby when the pin is inserted into the through-hole from the head end of the rivet body to the point that the protuberance on the movable leg engages with the first recess, the head of the pin is at a position outward from the outer surface of the head of the rivet body, when the head of the pin is pressed further inward to bring its outer surface flush with the outer surface of the head of the rivet body, the notch provided on the protuberance on the shank coming into engagement with the top of the protuberance on the movable leg and causing the movable leg to be deflected outwardly to increase the effective diameter of the leg member, and when the head of the pin is pressed inward still further to cause it to enter the large-diameter portion to the point where it strikes against the shoulder, the protuberance on the movable leg engaging with the second recess allowing the movable leg to close and reduce the effective diameter of the leg member.