| 摘要 |
PURPOSE:To facilitate the checking of the presence of cracks, by measuring the difference in thickness at the closing part of the upper end of the inner and outer side surfaces of a score. CONSTITUTION:Machining of a tear drop type, faucet shaped score is performed on a liquid paw end lid, and the cross section at a point B is observed. When constricted parts or cracks are not present, a difference t3 in plate thickness between a thickness t1 at an inside 21, which is surrounded by the score and a thickness t2 of an outside 22 is largely different. When the constricted parts and cracks 29 are yielded, a difference t4 with respect to the outside 22 caused by the increase in the plate thickness becomes small. The presence or absence of the fine cracks, which are hard to find, is numerically substituted, as the difference in the plate thickness at the closing position of the upper ends of the inner and outer sides in the score. Thus the presence or absence of the cracks can be readily determined. |
