STRUCTURE FOR CROSS-SHAPED GROOVE FORMED IN SCREW AND ALLOWING DRIVER BIT TO ENGAGE THEREWITH

WIPO Patent Application WO/2010/041437

A1

A screw configured such that a driver bit effectively engages with a cross-shaped groove of the screw to efficiently transmit rotational force of the driver bit to the screw. Left and right inner side surfaces of each of first to fourth wing grooves (5 to 8) which form a cross-shaped groove (10) provided in a head section (3) of a screw (1) are divided into a pair of base inner surfaces (11), a pair of intermediate inner surfaces (12), and a pair of front end inner surfaces (13).  The inner surfaces (11, 12, 13) are configured to have the relationship of (angle α1 of bend of a base inner surface (11)) < (angle α2 of bend of an intermediate inner surface (12)) < (angle α3 of bend of a front end inner surface (13)).  The base inner surfaces (11) which face each other define a trapezoidal base groove (14), the front end inner surfaces (13) which face each other define an inverted trapezoidal front end groove (16), and the intermediate inner surfaces (12) which face each other define an intermediate groove (15) located between and substantially parallel to the base groove (14) and the front end groove (16).  The inner surfaces (11, 12, 13) have the angles of elevation causing the inner surfaces to open wider toward an opening surface of the cross-shaped groove (10).

OGAWA NOBUHIRO (JP)
YOKOYAMA NAOKI (JP)

PCT/JP2009/005203

April 15, 2010

October 07, 2009

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CROWN SCREW CORP (JP)
OGAWA NOBUHIRO (JP)
YOKOYAMA NAOKI (JP)

F16B23/00

JP2009008134A	2009-01-15
JP2001193719A	2001-07-17
JP2005106269A	2005-04-21
JPH06511303A	1994-12-15
JP2008256124A	2008-10-23
JP2000108043A	2000-04-18
JPS5614614A	1981-02-12

ICHIHASHI, Shunichiro et al. (JP)
Shunichiro Ichihashi (JP)

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