Both molding method for manufacturing a two-piece tinplate cans are made of metal plate molding. This method is based in the complex stress, by rearranging the crystal structure exhibit metallic "liquidity" as the basis, and in the process material shall not fracture.
1. stamping. Namely the use of a punch press will burst into a flat cylindrical die, so that deformation of the plate from the cylinder. Cup diameter is formed after the initial pressing, stamping process can be applied again to zoom out. Then stamping process with a sleeve instead of stamping dies, installed between the punch and the inner diameter of the cup. And other area rules determine the reduced diameter is accompanied by increase in height, and then stamping process can be repeated once again, within a certain diameter limits gradually reduced, and to avoid metal fracture.
2, the cup wall thinning stretch. After punching in a cylindrical cup quilt punch, punch axially squeezed into a mold, the gap between the mold and the punch is smaller than the thickness of the cup wall, so that in diameter remain unchanged, the wall thickness on get thinner. After thinning the metal cylinder is equal to the volume of thin metal cup drawing process volume, it is also equal to the original volume of metal slabs. In the manufacture of the tank, this process is repeated two or three times, with a cup of punch has passed a series of molds, one stroke through a die. Will be installed in the most convenient method of punch stamped forest is thinned before the first stretch, once again stamping operation.
3, red cupping manufacturing. Cupping punch manufacturing process roughly as follows: Expand ordinary strip coil; Xu lubricants; cutting and a cup; then press; cup sidewall thinning stretch; bottom forming; Simplified correct height trimming; cleaning and treatment . Dry beverage cans, but also for the outer surface coating, printing and decorating, interior surface coating, the open end of the flange molding and shut. For food cans, the cleaning process carried out in the outer surface of the coating, forming an open end of the flange, and the inner surface of the cylinder pressure bellows cover or coating on the can end is pre-coated with a multi-die press plate manufacturing, lid pressure corrugated (ribs), to cover internal and external pressure. Here are the final steps crimping to form a double seaming. Place filling in the final seal to act as a gasket.