FASTENER WITH TAMPER-PROOF DRIVE HOLE

Japanese Patent JP2015017685

A

PROBLEM TO BE SOLVED: To provide a fastener with a tamper-proof drive hole which can smoothly remove a drive tool from the drive hole when receiving a drive force in a loosening direction.SOLUTION: A fastener with a tamper-proof drive hole has an erecting face 3a having a circular face 3c which forms a hexagon in a plane view at a head part 2, the circular face 3c having a circle for connecting apexes of the hexagon, and a drive hole 3 which is located at a position for connecting the erecting face 3a and the circular face 3c, and formed of a flank face 3d which extends to an oblique direction from a bottom side of the erecting face 3a. The fastener also has, as regulating means for regulating the fall of a hexagonal wrench 4, a step 5 in a position being a hexagonal apex in a plane view which is formed of the adjacent two erecting faces 3a, 3a. By this constitution, when the hexagonal wrench 4 is fit into the drive hole 3, an edge 4c of the hexagonal wrench rides on a cross position R1 of a side face 5b of the step 5 and a flank face 3d, and the hexagonal wrench 4 does not fall to a bottom face 3b. Therefore, when the hexagonal wrench 4 receives a drive force in the loosening direction, a tip of the hexagonal wrench 4 can ride over to the flank face 3d from the cross position R1, and the hexagonal wrench 4 can be smoothly removed from the drive hole 3.

TORII SHINGO
HAMANO SHINICHI

JP2013146301A

January 29, 2015

July 12, 2013

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NITTO SEIKO KK

F16B23/00

JPH09264312A	1997-10-07
JP3411441B2	2003-06-03

GB562248A	1944-06-23
US7273025B2	2007-09-25
US20060112920A1	2006-06-01

Onishi Masanao

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