GB634530A - Improvements in and relating to the production of tubular articles, such as tubular metal rivets - Google Patents

Abstract

634,530. Forging rivets &c. LINREAD, Ltd., and LYNALL, E. H. Aug. 18, 1947, No. 22932. [Class 83 (iv)] Dies.-In a method of cold forging a tubular article such as a flanged head tubular rivet having a shank with a non-uniform bore from a tubular blank with a uniform bore, pressure is applied longitudinally of said blank by a punch to cause internal upsetting of the blank on to a stepped mandrel carried by the punch, the blank being confined within a die cavity and the head flange being shaped by a die cavity in the punch. The blank 1 is preformed by a punch 6 having a tapered portion 5 and a flange forming die cavity 7, Fig. 2. An ejector 4 is then adjusted to lift the flange 1a above the die cavity 2, Fig. 6 (not shown), and the finishing operation is performed by a punch assembly, Fig. 5, comprising a hollow body portion 8 screwed to a base 13, a slidably mounted ram 11 having a sleeve-like forward end 10 and normally projected forward by a spring 19, and a mandrel 16 having a screwed connection with the base 13. In operation, as the member 13 descends, the spring-loaded ram 11, presses the blank hard down on the ejector 4 and thereafter is forced back until it abuts the base 13. The mandrel 16 meanwhile enters the bore of the blank and during the final stage when the body 8 engages the die 3 the metal of the blank is upset inwardly around the pilot portion 18 of the mandrel 16, Fig. 8. By adjusting the body 8 and mandrel 16 in relation to the base 13 the amount of retreat A of the ram 11 within the body 8 may be varied to forge flanges of different thicknesses. The smaller diameter portion of the bore of the rivet is subsequently tapped.