Blind-riveting assembly

Claim 1

A metal blind-riveting assembly comprising a rivet having a tubular body portion with a head flange at one end and an opposite end adapted to be deformed when the rivet is set and a mandrel having a stem of uniform cross section with a neck of reduced cross section at which the stem will break at a predetermined tension, which neck lies within the body portion of the rivet, the mandrel being upset at both ends, one of which forms a rivet-setting head while the other is a pulling head for engagement by pulling means of a rivet-setting tool, said pulling head being spaced from the rivet flange a distance substantially equal to the length of the rivet, and both the pulling head and rivet-setting head of the mandrel are of larger diameter than the diameter of the mandrel therebetween and each having an end face which is hemispherical and which terminates at a flat annular base facing the mandrel stem, said annular base joining said mandrel stem at a sharp corner, said rivet setting head having a diameter the same as that of said pulling head and being adapted to be partially enclosed in said opposite rivet end when the rivet is set to be locked therein, said reduced neck being located adjacent said rivet setting head so as to lie within the confines of the rivet body when broken upon setting the rivet, said hemispherical pulling and rivet setting heads having improved sliding properties when the blind riveting assembly is automatically fed into and through tubes or pipes.