| 摘要 |
This tool defines an inner opening (2) having a polygonal inscribed profile having six or twelve angles, said profile comprising grooves (3) at the place of said angles for the purpose of clearing the edges of the nut or bolt body to be driven, these grooves (3) being disposed between bearing surfaces (4) adapted to come into contact with the flat surfaces of said body so as to transmit the tightening or untightening torque. Said bearing surfaces (4) are convex in the direction toward the interior of the opening (2), the position of the contact edge of each bearing surface (4) being defined by a distance (x) to the mid-perpendicular (PM) of said flat surface, and the radius of curvature (R) at the contact of the profile of the bearing surface (4) being related to the value x by the relation: <IMAGE> in which: a is the dimension between the flat surfaces of the inscribed profile of the tool, x is the distance between the contact edge of the mid-perpendicular (PM) of the flat surface, R is the radius of curvature at the contact of the profile of the bearing surface.
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