Title:
【発明の名称】凹部付きねじ及びそのドライバビット
Document Type and Number:
Japanese Patent JPH0737805
Kind Code:
B2
Abstract:
A recessed screw (10) has a recess (12) formed in the head (11) of screw, and the recess (12) is defined as a superimposition of two equilaterally-triangular recesses (14) which each have arcuately shaped vertices (13) and are arranged coaxially with a phase shift of 60 DEG around a longitudinal axis of the screw. The recess (12) thus has six grooves 915) alternating with six driven vanes (16) having side walls (16a) extending parallel with the axis, and an inner ridge of each vane is a conically curved sticking wall (18) inwardly slanted towards a bottom of the recess (12). The cross-sectional area (A) of each groove (15) is larger than that (B) of each vane (16). A driver bit has six driving vanes in conformity with the grooves (15) and six valleys each interposed between the adjacent driving vanes and corresponding to the driven vanes (16) in the recess (12), such that a biting action appears between the recess (12) and the bit. The driving vanes (16) can be strengthened, and any conventional bit for Torx screws can be used with the recessed screw.
Inventors:
Katsumi Shinshiro
Application Number:
JP33254492A
Publication Date:
April 26, 1995
Filing Date:
November 17, 1992
Export Citation:
Assignee:
Shinshiro Seisakusho Co., Ltd.
International Classes:
B25B23/00; B25B15/00; F16B23/00; (IPC1-7): F16B23/00; B25B23/00
Domestic Patent References:
| JP55150975A | ||||
| JP4191513A |
Attorney, Agent or Firm:
Hideyoshi Takara
Next Patent: SEMICONDUCTOR THIN FILM GROWTH METHOD