Tapping screw
AssigneeAoyama Seisakusho Co., Ltd.
InventorsHirohisa Kajita, Kazunori Kouketsu, Naoki Hoshino
Life of this patent
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Abstract
The present invention is directed to provide a tapping screw for a soft material having a sufficiently large stripping torque compared to a driving torque and an increased tolerance of a fastening torque, and characterized in that it has threads each having a leading flank and a following flank, the leading flank being designed to be steeper than the following flank, that an R is imparted to a crest of each thread on the following flank side, that an R is also imparted to each flank at a portion contiguous to a root thereof and that the former R and the latter R being designed to connect smoothly to each other at the root.
Claims4
A tapping screw comprising:
- threads and roots, each of the roots being provided between two adjacent ones of the threads, and each of the threads comprising:
- a leading flank on an advancing side of the tapping screw which faces in a driving direction of the screw at a time of screwing, a following flank on a following side of the tapping screw which faces toward a head of the screw at the time of screwing, and a crest formed by a surface at a top portion of a ridge connecting the leading flank and the following flank,
- wherein:
- the crest has a convex part,
- the leading flank has a concave part between the crest and a next root on the advancing side,
- the following flank has a concave part between the crest and a next root on the following side,
- the following flank and the leading flank of the next root on the following side are connected smoothly therebetween at each of the roots, and
- a following flank angle of the following flank is larger than a leading flank angle of the leading flank in a vicinity of the crest.
Dependencies are inferred from the claim text.