| 摘要 |
Bottle necks (11) for screw-off caps are provided with external threads (14) to mesh with internal cap threads and external ratchet teeth (22) to engage internal cap ratchet teeth. The corners (28) are rounded off in a radius (R1) having its center offset from the intersection of the working flank (26) of the tooth (22) and the minor ratchet diameter (D1) without detrimentally reducing the length of the working flanks (26). Ratchet teeth (22) are usually located in two diametrically opposed quadrants. The transition tooth (23) of each quadrant has a greater radius than that of subsequent teeth and its center is inset toward the neck axis. In advance of the transition tooth (23) is a protective "tooth" (24) which is rounded and has no working flank (26).
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