| 摘要 |
<p>PURPOSE:To achieve good self-standing stability and prevent deformation of the hollow part in the middle of the bottom part by a structure wherein a bulging part consisting of an alternation of parts bulging outward and parts bulging inward both with respect to a grounded line is formed at the bottom, the bottom of each of the outwardly bulging parts forms a grounded plane, and the bottom of each of the inwardly bulging parts is slightly inclined upward toward the center. CONSTITUTION:Each of outwardly bulging parts 53 of the bottom part 5 has a rounded outer side 53a which gently bulges from the outer surface of the barrel 4, a rounded inner side 53b, and a bottom plane 53c which is formed continuously from said outer and inner sides. Each of inwardly bulging parts 54 has a rounded inner side 54a which bulges toward a hollow part 51 in the middle, a rounded outer side 54b which is formed substantially vertically at a grounded line 52, and a bottom plane 54c which is formed continuously from said inner and outer sides 54, 54b. The inwardly bulging part 56 has the rounded inner side 54a bulging inward from the grounded line 52 and has the bottom plane 54c slightly sloping upward with respect to a horizontal plane. The area of the grounded part is widened in the above structure and the inwardly bulging parts 54 prevent deformation of the hollow part in the middle.</p> |
