| 摘要 |
A battery case (1) is formed such that a thickness (t1) of a side wall (1a) with respect to a thickness (t0) of a bottom wall (1b) satisfies t1=alphat0 (alpha=0.2 to 0.7) undergoing an ironing step using ironing dies (11, 12, and 13) aligned in multiple stages, and that an inside face of the side wall is made to have a rough surface having average surface roughness of 0.2 mum to 2.0 mum by undergoing a drawing step after the ironing step. A manufacturing method of the battery case includes a first step of manufacturing a battery case element (7) by applying the DI processing to a cup-shaped intermediate product (4), and a second step of manufacturing a battery case by reducing an outside diameter to a predetermined outside diameter (r) without changing a thickness of a side wall by applying drawing processing to the battery case element by drawing dies (18 and 19) aligned in multiple stages.
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