1398719 Riveting; making blind riveting mandrels; drills TUCKER FASTENERS Ltd 11 Sept 1972 [10 Sept 1971] 42273/71 Headings B3U B3A and B3C [Also in Division F2] A self-drilling, blind riveting mandrel is made by upsetting a wire to form a setting head 12 between a pulling stem 16 and a stalk 18, flattening the stalk 18 to produce a web 26 which contains the axis of the stem 16 and which extends substantially diametrically across the head 12 at least as far as its periphery and providing the web 26 with cutting edges 22, 24. A steel mandrel blank 10 is first formed by upsetting a wire, projecting from gripping dies, by a heading tool to form a collar 12 between a stalk 18 and a pulling stem 16 which receives the tubular rivet 28. A neck 14 at which the mandrel breaks in the setting operation is swaged by the gripping dies. The stalk 18 is flattened by dies to form a curved web, which is ground to form cutting edges 22, 24. The drill tip 26 is finally heat treated. In another embodiment (Figs. 4 and 5, not shown) a web (20SP1/SP) is formed between dies (30) confined between die walls (32) which produce raked surfaces bounding side cutting edges (36). In a further embodiment (Figs. 6-9, not shown), the stalk 18 of the mandrel blank 10 is first flattened to form a flat sided web (20SP11/SP) which is swaged between dies (40, 42) to form a drill portion as described in Specification 1,195,246. The waste material (44, 46) is removed to expose cutting edges of the drill portion which is then heat treated.
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