| 摘要 |
PURPOSE:To improve sealability by making curvature inward at upper side of at least two faces of a sealed cover plate edge and making curvature inward at upper side of caulking part of a corresponding case opening, so that swelling the case opening outward is prevented. CONSTITUTION:After placing inside an L-type gasket 2, which has been injection-molded with a resin, a sealed cover plate 3 is inserted into opening of a metal case 1. Two facing fringe surfaces of the sealed cover plate 3 are formed with inward curvature at the upper side. Then, using a drawing die 4, which has a leading taper D1 with a concave lens-like opening at the upper side, an opening of the metal case 1 is curved by drawing to complete an angular enclosed battery. By such a drawing process, an inward curve, in the top view, of linear part at the opening of metal case 1 is formed, resulting in an excellent battery with good sealability and no possibility of hazardous ellipsoidal expansion of the opening in the metal case 1. |
