Threaded Milling Screw for Chipless Metal-to-Wood Fastening
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Solution Overview
Problem
Existing screws for fastening metal components to wooden substructures face challenges in penetrating metal sheets without chipping and securely anchoring in wood, leading to corrosion from metallic drill chips and requiring pre-drilling for efficient fastening.
Innovation Solution
A screw design featuring a threaded tip with a double thread, a cylindrical milling section with steep ribs, and a smooth shank section, allowing chipless penetration of metal sheets and reduced torque in wood, while avoiding undesirable metal deformation and chip formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a drill tip is used to penetrate metal sheets, then penetration capability is improved, but metallic drill chips are produced causing corrosion
Solution Approach 1:
The patent changes the fundamental mechanism from cutting (drill tip) to deformation (threaded tip). The threaded tip displaces and deforms metal rather than removing it, eliminating chip generation while maintaining penetration capability. This parameter change in the interaction mechanism resolves the contradiction between penetration speed and chip formation.
Solution Approach 2:
The patent replaces the cutting mechanism (drill tip) with a thread-forming mechanism (threaded tip). Instead of using rotational cutting edges to remove material, the threaded tip uses helical deformation to penetrate and anchor, substituting one mechanical system for another that avoids the harmful side effect of chip generation.
2Object-generated harmful factors
If a threaded tip is used instead of drill tip, then chip formation is reduced, but penetration efficiency decreases
Solution Approach 1:
The screw is divided into functionally distinct sections: a threaded tip section for penetration and a threaded shank section for anchoring. The threaded tip is optimized for cutting through metal with reduced chip formation, while the shank provides secure anchoring. This segmentation allows each section to be optimized for its specific function, improving overall penetration efficiency while maintaining low chip formation.
Solution Approach 2:
The patent employs a double thread design in the tip section with different pitch and flank angle characteristics. The dynamic interaction between the threaded tip and metal sheet allows for efficient material displacement and penetration. The threaded geometry dynamically adapts to the metal deformation process, maintaining penetration efficiency without generating excessive chips.
3Reliability
If pre-drilling is performed before fastening, then anchoring security is improved, but manufacturing complexity increases
Solution Approach 1:
The threaded tip performs the preliminary action of creating the anchor hole during the fastening process itself. As the threaded tip penetrates the metal sheet, it simultaneously forms the thread structure that will provide anchoring. This eliminates the need for separate pre-drilling operations, reducing manufacturing complexity while maintaining anchoring security through the self-forming thread structure.
Solution Approach 2:
The threaded tip is self-sufficient in creating both the penetration path and the anchoring structure. The thread formation occurs automatically during the fastening operation without requiring external pre-processing. The screw serves itself by creating its own anchor hole through the deformation and displacement of metal by the threaded geometry, eliminating additional manufacturing steps.
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 effectively penetrates metal sheets without chipping and securely anchors in wood, reducing the need for pre-drilling and minimizing corrosion risks, with improved handling efficiency and cost-effectiveness.
Implementation Method 1
an essentially cylindrical milling section with a plurality of milling ribs, which are designed as steep threads
Implementation Method 2
the metal of the sheet is not removed by cutting away, but displaced and deformed. The thread on the cone of the threaded tip additionally cuts a thread in the displaced metal and thus supports the advance of the screw
Data Source
AI summary
A screw having the following successive functional sections: a threaded tip (150) shaped as a cone (A) having a double thread; a milling section (B) having a plurality of milling ribs (160) with outer diameter DF; a cylindrical shank section having the main thread with diameter DN; a thread-free shank section (D); optionally a holding thread section (E); optionally a short thread-free underhead section (F); and a head section (G) having a force engagement. The main thread (110) is guided continuously from the tip section (190) of the cone (A) via the milling section (B) to the head end of the thread-bearing shank section (C) and the ribs of the milling section (B) are arranged recessed in the thread base (140) of the continuous main thread such that the thread tips of the continuous main thread with nominal outer diameter DB project beyond the milling ribs, so that DF<DB.