Wood Screw Thread Geometry for Low Torque and Split Resistance
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Solution Overview
Problem
Conventional wood screws face issues with high tightening torque, material splitting, and reduced extraction and releasing torque due to the cutting of wood fibers, leading to increased force expenditure and potential damage during tightening and removal.
Innovation Solution
The wood screw design features alternating projections on threaded turns that cause additional longitudinal material displacement, allowing reversible deformation and increased thread extraction force without radial displacement, reducing the splitting effect and optimizing torque levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional wood screws cut wood fibers to form threads, then the thread extraction force is improved, but the tightening torque increases and material splitting occurs
Solution Approach 1:
The thread winding is segmented into multiple discrete threaded turns with gaps between them. This segmentation allows material to be displaced longitudinally through the gaps rather than being compressed radially, reducing tightening torque while maintaining thread extraction force through the distributed engagement of multiple turns.
Solution Approach 2:
The invention transitions from radial material displacement (conventional threading) to longitudinal material displacement. By arranging threaded turns with gaps along the longitudinal axis, material is pushed forward through the gaps rather than being compressed sideways, fundamentally changing the displacement dimension and reducing radial pressure that causes splitting.
2Strength
If conventional wood screws cut wood fibers, then thread extraction force is achieved, but chips are produced that reduce releasing torque
Solution Approach 1:
The invention extracts or removes the harmful byproduct (chips) by preventing their formation in the first place. Through longitudinal displacement and material flow through gaps, fibrous material is pushed forward cleanly rather than being cut and left as chips, eliminating the source of reduced releasing torque.
Solution Approach 2:
The invention converts the potentially harmful cutting action into a beneficial pushing action. Instead of cutting fibers and creating chips that hinder removal, the threaded turns push material longitudinally through gaps, creating clean displacement that actually facilitates easier removal while maintaining extraction force.
3Strength
If material is displaced radially during tightening, then thread engagement is improved, but the splitting effect increases
Solution Approach 1:
The invention fundamentally changes the displacement direction from radial to longitudinal. Threaded turns are arranged with gaps along the longitudinal axis, causing material to flow forward through the gaps rather than being compressed radially outward, thereby eliminating splitting while maintaining engagement through longitudinal pushing action.
Solution Approach 2:
Different regions of the screw thread serve different functions: the threaded turns provide engagement through longitudinal pushing, while the gaps between turns allow material flow and prevent radial compression. This local differentiation of function within the thread structure enables simultaneous achievement of engagement and splitting prevention.
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
This design enhances the thread extraction force while minimizing the splitting effect and reducing the tightening torque, ensuring the wood screw remains securely attached without causing material damage during tightening and easy removal with a higher releasing torque.
Implementation Method 1
This displacements effects a reversible deformation of the material upon passage of one of the projections when the screw is twisted in, whereby the material then may return into the initial state.
Data Source
AI summary
A wood screw, including a cylindrical screw shank, at the end of which there is formed a tip, a screw head, which is formed at the other end of the screw shank, as well as a threaded section, which extends from the tip in the direction of the screw head, wherein the threaded section has a thread core and a thread winding having several threaded turns circulating the thread core, wherein several successive threaded turns have projections, which are formed alternatingly in essentially the direction of the screw head and in essentially the direction of the tip.