| 摘要 |
<p>PROBLEM TO BE SOLVED: To prevent flexion due to load from occurring to the lowermost step part of a container even though the lowermost step part is formed broadly in width by providing hollow ribs alternately from the inside and the outside at a circumferential wall of a domelike bottom wall. SOLUTION: The structure of bottom of the container is composed of a thin grounding periphery 2 connecting to a circumferential side wall 1 being integral with a drum part, and a bottom wall 3 of a domelike shape surrounded by the grounding periphery 2 and comprising of a plurality of steps formed at the circumferential wall. The top part 7 of the bottom wall 3 is formed in a thickness the same as that of an uppermost step part 4. The circumferential wall extending from the uppermost step part 4 to the grounding inner edge is formed by drawing thin, approximately same as that of the grounding periphery 2. At least three hollow outer ribs 8 relatively narrow in width are provided radially at equal intervals at parts extending from the top part 7 to an inner edge 6a of a lowermost step part 6. Hollow inner ribs 9, bigger in width than the outer ribs, extending from the uppermost step part 4 to the in-plane 6b of the lowermost step part 6 are provided between the outer ribs 8, and flexion of the lowermost step part 6 due to load can be prevented.</p> |
