GB1396315A - Fasteners - Google Patents

Abstract

1396315 Riveting; making blind riveting mandrels; drills; jointing by forging; TUCKER FASTENERS Ltd 11 Sept 1972 [10 Sept 1971] 42272/71 Headings B3U B3A B3C and B3H [Also in Division F2] A self-drilling, blind riveting, mandrel device comprises a setting collar 26 positioned between a stem 24 and a coaxial stalk 28 which receives an axially extending recess in a drill element D. The mandrel M is formed by upsetting a steel wire to form a collar 26 between a stalk 28 and a pulling stem 24 which receives the tubular rivet R. The stem 24 is formed with a neck 32 at which the stem 24 breaks in the setting operation. The stalk 28 may be knurled by rolling (Fig. 8, not shown), swaged to form two fillets (42) (Fig. 7, not shown), or formed into a substantially square cross-section (Fig. 9, not shown). The drill element D is made (Figs. 1-4, not shown), by die forming a steel blank (34) to produce an annular flange (36) and a recess (30), after which the blank is swaged between dies as described in Specifification 1,195,246, to form a drill tip having an elliptical cross-section and two longitudinal flutes. The cutting edges of the drill tip are carbonized after removing waste metal (38, 40). The flange (36) of the drill element D is broken off when the element D is forced on to the mandrel stalk 28. The mandrel stalk 28 may be glued in the recess (30) of the drill element D with adhesive and the stalk 28 and recess (30) may be screw threaded. Alternatively, the stalk 28 may have a frusto-conical (Fig. 6, not shown), or cruciform shape (Fig. 11, not shown), to facilitate detachment of the drill element D after rivet setting. In another embodiment (Figs. 12 and 13, not shown), the drill element D is formed around the mandrel stalk 28 by swaging the end of a steel tube (60), heated by coils (62), on to the stalk 28.