| 摘要 |
PURPOSE:To prevent a side wall from buckling at the time of die cutting in a synthetic resin cap with degasing groove. CONSTITUTION:A screw 7 comprises a multiple linear region (a) with two threads 8 formed in an axial direction and a single linear region (b) with a single thread formed wherein an effective number of windings is 1 or more, a degasing groove 8 is formed only on the thread in the multiple linear region (a), the thread ends in a state of an effective thread without a thread ending part at a terminal of the thread, and at least an initial end 10 of the thread in the single linear region is connected to a thread 82 in the multiple linear region via the degasing groove 9. Therefore at the time of die cutting, force applied to a cap via the threads are approximately uniformly dispersed to an entire periphery of a cap side wall, so that hanging of the screws, buckling and deformation of the side wall can be prevented. |
