SELF PERFORATING AND THREAD FORMING CONNECTING ELEMENT

摘要

A self-perforating thread-forming screw has a single or multiple thr ead which is designed for screwing into soft materials such as wood, plywood or composite materials without predrilling. The screw has a low tightening moment and a high loosening and pull-out moment. The thread of the screw at the screw tip is shaped to provide good radial displacement of the material with low moments while also contributing to a high retaining force. Efficient radial displacement of the material at th e screw tip as opposed to efficient cutting of the material produces this desired result.