| 摘要 |
PURPOSE: To prevent generation of cracking by forming an R (radius of curvature) in a shoulder part of a battery can in a specific value or less, so as to suppress decreasing mechanical strength in the shoulder part of the battery can after a positive electrode compound is press fitted. CONSTITUTION: As a battery can material, a nickel plating steel plate about 0.4mm thick is used, to supply this material to a press machine as a pool material. By the press machine, a battery can material is punched in a prescribed shape by a deep drawing process, to obtain a cup-shaped intermediate product 1 by performing deep drawing. A thickness p1 , q1 in a side peripheral part 1a and bottom part 1b of the intermediate product 1 is almost equal to the thickness of the material. Next, a drawing and concurrently squeezing machine is used, to apply at a stroke preliminary forming work, 2-step drawing work, 3-step squeezing work and forming work to the product 1, so as to obtain a battery can 2 withγin a shoulder part 0.3mm or less. Thus by combining the deep drawing process and squeezing process, a battery can with a small R (radius of curvature) in a shoulder part is easily obtained, and liquid leakage can be prevented. |
