Patent ID: 6499329
Filing Date: 2002-12-31
Classification: B21D

Abstract:
A bottle-shaped can manufacturing method for forming a shoulder portion having a slope and a diametrically small cylindrical neck portion integrally by further working a bottom side of a bottomed cylindrical can which is formed thinner at its trunk wall than at its bottom wall by drawing a metallic sheet having a thickness of 0.1 to 0.4 mm and by executing a thinning working of at least one of a bending/extending working and an ironing working, comprising:a step of preforming a bottom corner portion of said can into a curved shoulder face having an arcuate longitudinal section; a first diametrically small cylindrical portion forming step of drawing the bottom of said can, with the curved shoulder face of said bottom corner portion being unwrinkled, into a diametrically smaller bottomed cylindrical shape than the trunk portion by using an unwrinkling pusher having a curved face shape of said shoulder portion on an outer face shape of its leading end portion, a drawing die having a curved face shape of said shoulder portion on an inner face shape of its leading end portion, and a drawing punch; a second diametrically small cylindrical portion forming step of drawing the bottomed cylindrical portion drawn from the can bottom into a diametrically smaller bottomed cylindrical shape, with said bottom corner portion being unwrinkled by surfaces of a tool including an unwrinkling pusher having at its leading end portion a tapered face having a substantially straight longitudinal section profiling a tangent line to an arcuate longitudinal section of a virtual curved face leading to said preformed curved shoulder face, a re-drawing die having a tapered face of a straight longitudinal section profiling a tangent line to an arcuate longitudinal section of a virtual curved face leading to said curved shoulder face at its portion to face at least said tapered face of said pusher, and a re-drawing punch; and a shoulder portion reforming step of pushing and extending the shoulder portion, which is formed by said first diametrically small cylindrical portion forming step and said second diametrically small cylindrical portion forming step into a smooth slope leading to the curved shoulder face on the trunk side, after a diameter of the bottomed cylindrical portion formed by executing the drawing working of said second diametrically small cylindrical portion forming step once or two or more times becomes substantially equal to a diameter of said neck portion.