Timber-Concrete Composite Screw With Variable Timber Thread Wedging
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Solution Overview
Problem
Existing composite screws for securing timber elements to concrete bodies require high manufacturing effort and do not achieve optimal performance in terms of wedging and anchoring.
Innovation Solution
A screw design featuring axially offset, helically aligned concrete and timber threads, where the timber thread has an engagement zone with increasing width towards the rear end, enhancing displacement of timber material and wedging within the timber element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the timber thread has constant width throughout its length, then the manufacturing process is simple, but the wedging and anchoring performance is insufficient
Solution Approach 1:
The timber thread is designed with variable width along its axial length, where the thread width increases from the thread start toward the thread end. This local variation in geometry creates enhanced wedging action in the engagement zone without requiring complex manufacturing processes, resolving the contradiction between performance and simplicity.
2Strength
If the timber thread width increases towards the rear end, then wedging and anchoring efficiency is enhanced, but manufacturing precision requirements increase
Solution Approach 1:
The thread width parameter is systematically varied along the axial direction of the timber thread, transitioning from a smaller width at the start to a larger width at the end. This controlled parameter change achieves enhanced anchoring efficiency while maintaining manufacturability through standard threading processes.
3Reliability
If the engagement zone includes multiple turns of the timber thread, then the anchoring security is improved, but the screw length increases
Solution Approach 1:
The engagement zone is designed to include multiple turns (at least one, preferably 1.5 or two turns) of the timber thread with increased width, providing sufficient anchoring security for typical applications. This partial extension beyond the minimum single-turn requirement achieves reliable performance without unnecessarily increasing overall screw length.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The screw achieves efficient wedging and anchoring within the timber element at low manufacturing effort, preventing gap formation and ensuring secure attachment to the concrete body.
Implementation Method 1
The width increase towards the rear might entail additional displacement of timber material in the mating thread previously tapped by the concrete thread, leading to particularly efficient wedging and anchoring
Implementation Method 2
leading to particularly efficient wedging and anchoring (e.g., due to contact at both flanks of the timber thread) within the timber element
Data Source
AI summary
A screw includes a shank which has a tip end and a rear end. A concrete thread and a timber thread are disposed on the shank. The concrete thread and the timber thread are helically aligned with one another and the concrete thread reaches further to the tip end than the timber thread. The timber thread has an engagement zone which includes at least one turn of the timber thread and, in the engagement zone, the timber thread becomes wider with decreasing distance from the rear end.