SAFETY CAP EQUIPPED WITH CR MECHANISM

PROBLEM TO BE SOLVED: To provide a safety cap equipped with a CR mechanism capable of establishing a frictional resistance force sufficient at a fastening completion position, although it can be rotationally operated smoothly up to a fastening completion position, thereby to prevent the co-rotation of an inner lid.SOLUTION: Although the lower side flank of a female screw thread 8 is pressure-welded to the upper flank of a male screw thread 3 on the upper side of a longitudinal middle part 8A of a female screw thread 8, the width of the female screw thread 8 on the side lower than the middle part 8A is made so relatively small on the lower side of the intermediate part 8A that a clearance may be formed between the lower side flank of the female screw thread 8 and the upper side flank of the male screw thread 3.SELECTED DRAWING: Figure 1 【課題】スムースに締め込み完了位置まで回転操作できるものでありながら、締め込み完了位置で十分な摩擦抵抗力を生じさせ、内蓋の供回りを防止できるＣＲ機構を具備する安全キャップを提供する。【解決手段】締め込み完了位置で、雌ねじ山８の長手方向中途部８Ａから上部側では雌ねじ山８の下側フランクが雄ねじ山３の上側フランクに圧接する一方、中途部８Ａより下部側では雌ねじ山８の下側フランクと雄ねじ山３の上側フランクとの間に隙間を有するように、中途部８Ａより下部側の雌ねじ山８の幅を比較的小さくする。【選択図】図１