| 摘要 |
PROBLEM TO BE SOLVED: To provide an injection mold having a simple structure and minimizing the occurrence of dragging in a thread forming part. SOLUTION: The outer diameter 30 and valley diameter 33 of the thread formed to the female thread forming part 14 of a screw mold are tapered so as to gradually become small as going toward the leading end of the female thread forming part 14 from the root thereof. The diameter 31 at the root of the female thread forming part 14 of the outer diameter 30 is equal to the valley diameter 36 of a female thread of the same nominal diameter prescribed in ISO or the like and the diameter 32 at the leading end of the female thread forming part 14 is slightly larger than the outer diameter 38 of a male thread of the same nominal diameter. The diameter 34 at the root of the female thread forming part 14 of the valley diameter 33 is equal to the inner diameter 37 of the female thread of the same nominal diameter and the diameter 35 at the leading end of the female thread forming part 14 is slightly larger than the valley diameter 39 of the male thread of the same nominal diameter. The dimension of the taper provided to the outer diameter 30, that is, the value of 1/2 of the difference between the diameters 31 and 32 is set smaller than the clearance between the valley diameter 36 and the outer diameter 38. Even the dimension of the taper provided to the valley diameter 33 is set in the same way. The dimension of the taper is preferably set to almost 60% of the clearance. COPYRIGHT: (C)2010,JPO&INPIT |
