Title:
SCREWDRIVER BIT
Document Type and Number:
WIPO Patent Application WO/2007/020681
Kind Code:
A1
Abstract:
A screwdriver bit capable of securely removing a screw by loosening it even when
a screw shaft or a screw head part is rusted or the sector-shaped walls of operation
grooves on the screw side is cut off and capable of removing even a flat countersunk
head screw having a head part sunk into a tightened surface. Rib-like projections
(12) forming a cross shaft portion (4) comprise rib peripheral surfaces (13)
tilted in a converging state and the peripheral surfaces (14) of pairs of bottom
grooves (8) holding the rib peripheral surfaces (13) therebetween. One side
ridges of the rib peripheral surfaces (13) are set at loosening side edges (15).
The rib peripheral surfaces (13) are formed to cross perpendicularly to the center
axes (P) of the projections of the rib-like projections (12) and to be positioned
on the inner side of virtual planes (Q) passed through the loosening side edges
(15). Accordingly, the rib peripheral surfaces (13) are prevented from coming
into contact with the radial outer end faces of the operation grooves (30) in such
a state that the cross shaft portion (4) is engaged with the operation grooves
(30) of the screw. A plurality of cutouts (20) are formed at each of the loosening
side edges (15) of each of the rib-like projections (12). Thus, the screw can be
securely loosened by securely crimpingly engaging the vertical intermediate
parts of the loosening side edges (15) with the base end corner parts of the sector-shaped
walls (31).
Inventors:
TAKASAKI MITSUHIRO (JP)
KAWAI SHINNOSUKE (JP)
KAWAI SHINNOSUKE (JP)
Application Number:
PCT/JP2005/014854
Publication Date:
February 22, 2007
Filing Date:
August 12, 2005
Export Citation:
Assignee:
ENGINEER KK (JP)
International Classes:
B25B15/00
Foreign References:
| JPS4315438Y1 | 1968-06-27 | |||
| JPS364449B1 | ||||
| JP2000167775A | 2000-06-20 |
Attorney, Agent or Firm:
ORIYOSE, Takeshi (3-21 Suehirocho, Kita-k, Osaka-shi Osaka, JP)
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