GB524146A - Improvements in and relating to the manufacture of hollow articles by extrusion - Google Patents

Abstract

524,146. Extruding hollow articles. HIGH DUTY ALLOYS, Ltd., and HERON, J. A. Jan. 20, 1939, No. 2008. [Classes 83 (ii) and 83 (iv)] Hollow articles such as gas bottles and airscrews are extruded from light alloys such as those of aluminium and magnesium by means of a die and mandrel the extrusion being over the mandrel shaped to form the closed end, the die having a constriction that determines the outside diameter of the article which is formed with an externally thickened wall at the open end. A billet 3 is placed on a die 8 within a container 2 having an enlarged mouth 9. The first action of the mandrel 4, that has an end shaped according to the desired form of the closed end of the container, is to upset the billet to fill the spaces 10 and 13, part of the metal being extruded backwards to form the thickened end 12, Fig. 3. The sleeve 7 now contacts the container and forces this downwards over the die 8 extruding the metal between the constriction 11 and the mandrel to form the bodv 1. The stroke terminates before the constriction reaches the top of the die so forming a handling ring 14 on the article. After removal of the mandrel 4 and die 8 a further mandrel may be used to force the large end 12 through the constriction 11, the rear surface 15 being bevelled for this purpose, thus transferring the extra metal to the inner surface. The neck may be further reduced by swaging or spinning, and these processes may be employed instead of forcing the article through the container which must then be sectional to permit removal. In a modification the constriction 21 of the container is at the lower end and the mandrel has two diameters 22, 19, the latter such as to act as a ram in the part 23 of the container. In this form extrusion is first backwards over the part 22 of the mandrel until this reaches the constriction 21 when it shapes the closed end of the article. The shoulder 27 then acts as a ram extruding the body of the bottle forwards over the mandrel and finally forming the thickened open end in conjunction with the tapered part 24 of the container which may be employed subsequently similarly to the bevelled surface 15. Specifications 518,037, 524,152 and 524,189 are referred to.