GB778545A - Method and apparatus for making a container body of sheet metal - Google Patents

Abstract

778,545. Making containers; stampings. NAAMLOOZE VENNOOTSCHAP VALEVEFA. Feb. 1, 1956, No. 3189/56. Classes 83 (2) and 83 (4). A method of making a container body of sheet metal, said body having a rectangular crosssection with rounded corners and an offset marginal edge at one extremity connected to said body by a shoulder comprises making a cylindrical body of sheet metal and deforming it by applying outwardly directed pressure at four circumferentially spaced zones thereby straightening the four portions of the body wall between said zones whilst decreasing the radius of curvature of said body wall in said zones. The apparatus comprises a top plate 12 connected to a bottom plate 11 by tie rods 13. Four pressure members 14 having transversely curved operating faces are slidably mounted between the plates by guides 15 engaging in slots 16 in the pressure members. The outward movement of the spring-loaded pressure members is effected. by a draw-bar 17 having two conical members 18 engaging complementary faces 19 on the pressure members. Two sets of springs 20 and 21 urge the pressure members inwardly. Four anvils 26 are positioned on the table 11 and each have a concave face comprising a portion 26a engaging the container body A, a portion 26b engaging the offset edge B of the container and an inclined portion 26c engaging the shoulder C of the container. In making the container, a cylindrical body A having an offset edge B and shoulder C is made from sheet metal (Fig. 6), by a pressing or rolling and seaming or welding operation. The cylindrical body is placed in the apparatus and deformed into a body having a rectangular cross-section with rounded corners. Finally the apparatus is collapsed and the deformed body A removed to be further operated on to form a container as shown in Fig. 5. Prior to uniting the ends of the container by a seaming operation, the edge B is flanged as at B<SP>1</SP> (Fig. 7), and the width of the flange at the former zones B<SP>2</SP> is found to be larger than the straight zones and this causes difficulties in the seaming operation. To overcome this, one or more indentations D are made in each corner zone by ridges 27 in the anvils 26 which co-operate with slots in the pressure members. To facilitate removal of the formed container the anvils are slidably mounted in guides 29 and held in position by wedges 30 operated by pneumatic actuators 31. When the wedges are removed the anvils are withdrawn by springs 32. The clearance between the anvils and the pressure members is adjusted by set screws 37 mounted on the lower plate 11.