| 摘要 |
A new and improved threaded fastener comprises a first, primary thread lead, and a pair of second, auxiliary thread leads alternatively interposed between successive threads of the first, primary thread lead. The threaded fastener further comprises a pointed tip portion for initiating driving insertion of the threaded fastener into an underlying workpiece, and that portion of the dual reinforcing lead, which has previously been interposed between the tip portion and the primary thread lead, or between the first and second successive threads of the first primary thread lead, has been removed. In this manner, a circumferentially extending space has effectively been created for permitting chips or debris, normally generated during the self-tapping of the threaded fastener into a bore previously pre-drilled within the underlying workpiece, to be temporarily accumulated within such circumferential space whereby such chips or debris can subsequently be automatically discharged from such space into the depths of the pre-drilled bore as the threaded insertion of the threaded fastener into the pre-drilled bore of the workpiece proceeds. This structure reduces torque insertion levels and permits enhanced depth penetration of the threaded fastener into the workpiece. The fastener also comprises lobe members formed upon the primary thread lead so as to predeterminedly affect torque insertion and pull-out resistance values. |
