Thread forming screw for use on foundation formed of hard construction materials e.g. concrete, has each thread root having conical shape that enlarges in diameter towards each thread flank of threaded portion along screwing direction

摘要

A thread forming screw (1) has a head (2), an unthreaded shank (3), and a spiral threaded portion (4) comprising of thread roots (5) and thread flanks (6). Each thread root, assuming conical shape, enlarges in diameter towards each associated flank along a screwing direction. The screw is embedded into the foundation via hardened mass (10).