| 摘要 |
A recessed screwing driving assembly comprises a driving portion having an engaging opening; each apex of the engaging opening being formed as an apex recess which has a concave cambered shape; a middle section of each side of the engaging opening being formed with a middle side; between each middle side and an adjacent apex recess being formed with a first recess and a second recess. The first recess has two straight sides and a concave cambered lower bottom; the two straight sides of the first recess are inclined to the first side and are extended from the first side toward a direction far away from the first side. The slope of the side of the first recess near the apex recess is greater than that of the other side of the first recess. The second recess has a shape like that of the first recess.
|
