GB745740A - Improvements in or relating to the extrusion of elongated bodies - Google Patents

Abstract

745,740. Extruding. KREIDLER, A. Dec. 30, 1952 [Dec. 31, 1951], No. 32924/52. Class 83 (4). [Also in Group V] An elongated body having portions of different cross-section and in which the rear part at least is hollow, is made by extruding a billet successively through dies of different cross-sections, the hollow portion being formed by a mandrel. A solid billet 9 is first pierced by a mandrel 8 and simultaneously a portion of the billet is extruded through a die 4. The latter is then replaced by a die with a larger orifice and the remainder of the billet is extruded as a tube between this orifice and the mandrel by a ram 7. In another embodiment, Fig. 9, a hollow cylindrical billet 15 is extruded between a mandrel 23 and a pair of dies 17, 18 with different sized orifices. The dies are held in position by removable stops such as 21 slidable in guideways 27. Each stop carries a cam 28 co-operating with a spring-loaded slide 32 which, during the initial part of the extrusion process, holds the stop 21 in engagement with the die 18. At a predetermined point in the process, arms 37 on the press ram 22 engage the slides 32 and thus release the stops 21 whereby the die 18 is then carried loosely by the smaller portion 14 of the extruded body whilst the remainder of the billet is extruded through the die 17 only. In a modification the slides 32 are actuated by solenoids controlled by a switch engaged by the portion 14 of the extruded body. The slides may alternatively be released by hydraulic or pneumatic means.