Self-Tapping Screw Insertion End for Stable Concrete Anchoring
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Solution Overview
Problem
Self-tapping screws face challenges in easily and reliably screwing into drilled holes, particularly in hard or porous materials like concrete, due to tilting issues and material blockage, which increases screwing torque and risks of being torn out.
Innovation Solution
A self-tapping screw design featuring a tapered, thread-free insertion end with longitudinal grooves to stabilize the screw and prevent material blockage, along with a specific thread pitch and cutting thread configuration to reduce insertion torque and enhance anchoring stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a self-tapping screw is designed with a standard threaded insertion end, then it can provide anchoring stability, but it risks tilting relative to the drill hole axis and increasing screwing resistance
Solution Approach 1:
The screw is divided into functionally distinct sections: a thread-free tapered insertion end for easy entry and alignment, and a threaded cutting thread section for anchoring. This segmentation allows each section to optimize its specific function without compromise.
Solution Approach 2:
The tapered insertion end performs the preliminary action of entering the drill hole and self-aligning the screw axis with the hole axis before the cutting threads engage. This preliminary alignment prevents tilting during the subsequent screwing process.
2Reliability
If the insertion end is made longer to improve positioning stability, then alignment improves, but the screwing torque increases and anchoring stability may be compromised
Solution Approach 1:
The insertion end features a tapered geometry with gradually varying diameter along its length, optimizing the balance between positioning stability and screwing torque. The taper angle and length are specifically designed to provide sufficient alignment while minimizing resistance.
3Ease of operation
If longitudinal grooves are added to remove drilling dust and prevent blockage, then screwing resistance decreases, but the structural integrity and load-bearing capacity may be reduced
Solution Approach 1:
Longitudinal grooves are provided only on the insertion end where material removal is needed for smooth entry, while the cutting thread section maintains full threaded structure for optimal anchoring strength. This localized application of grooves balances ease of screwing with load-bearing capacity.
Data Source
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Figure 2
AI summary
A self-tapping screw comprises a core (2) having a longitudinal axis (3) and a nominal diameter (dN), a cutting thread section (11) integrally formed on the core (2) with a cutting thread (13) having a thread pitch (h) and a shank diameter (ds), a torque transmission section (4) integrally formed on the core (2), and an insertion end (9). The insertion end (9) is unthreaded and has an insertion length (LE). The following applies: 0.5 dN ≤ h ≤ 0.95 dN. At least one longitudinal groove (16) is provided on the insertion end (9).