Screw With Force Decoupling Section for Porous Material Anchoring
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Solution Overview
Problem
Existing screw anchoring methods in porous materials like concrete are complex, time-consuming, and require hardening compounds, which can lead to issues with adhesion and structural integrity under dynamic loads such as vibrations or earthquakes.
Innovation Solution
A screw design with distinct sections along its central longitudinal axis, featuring a cutting thread for insertion, a force decoupling section with a smooth surface to prevent adhesion, and a prestressing section for self-expansion, allowing for immediate preload application without the need for additional compounds and enhancing structural flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a hardenable compound is used to anchor the screw in the borehole, then the anchoring strength is improved, but the installation time increases due to waiting for hardening
Solution Approach 1:
The patent extracts the hardenable compound from the essential anchoring mechanism, making it optional rather than mandatory. The screw can be anchored purely mechanically through the cutting thread, eliminating the time-consuming hardening waiting period while maintaining anchoring strength through the mechanical interlocking of the cutting thread with the borehole wall.
Solution Approach 2:
The screw is segmented into distinct functional sections: a cutting thread section for mechanical anchoring, a force decoupling section with smooth surface to prevent adhesive bonding, and a prestressing section. This segmentation allows the screw to achieve anchoring through mechanical cutting alone, separating the anchoring function from adhesive bonding and eliminating the need to wait for compound hardening.
2Strength
If the screw is glued along its full length in the drill hole using hardenable mass, then the anchoring is improved, but the ability to tolerate dynamic vibrations is reduced
Solution Approach 1:
The screw applies different surface qualities to different sections: the cutting thread section has a rough, engaging surface for mechanical anchoring, while the force decoupling section has a smooth surface that prevents adhesive bonding. This local differentiation allows the screw to maintain strong mechanical anchoring where needed while remaining flexible and vibration-tolerant in the prestressing section.
Solution Approach 2:
The force decoupling section with its smooth surface creates a dynamic interface that allows the screw to move slightly and absorb vibrations. This section acts as a flexible element that can accommodate dynamic loads and oscillations without transferring rigid constraints, enabling the screw to tolerate earthquakes and vehicle-induced vibrations.
3Device complexity
If a cutting thread is used to screw directly into the material, then the anchoring complexity is reduced, but the risk of unintentional displacement or falling out increases due to dead weight
Solution Approach 1:
The cutting thread is designed to create preliminary mechanical interlocking with the borehole wall during the screwing process. The cutting action forms undercut features that mechanically lock the screw in place, preventing unintentional displacement or falling out due to the screw's dead weight before any prestressing force is applied.
4Reliability
If the screw is made from steel material for self-expansion, then the preload maintenance is improved, but the cost increases
Solution Approach 1:
The screw utilizes the physical parameter of elastic expansion inherent to steel material. When prestressing force is applied, the steel screw elastically expands, creating strong frictional contact with the borehole wall and maintaining preload. This leverages the natural elastic properties of steel to achieve reliable preload maintenance without requiring additional expensive components or complex mechanisms.
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
Enables efficient, error-free, and time-saving screwing into drilled holes, maintaining preload under dynamic conditions, and providing flexibility against vibrations and seismic loads without the need for additional anchoring compounds.
Implementation Method 1
a cutting thread (16) extending along a cutting thread section (ASG) located at the insertion end (13). The cutting thread (16) serves to cut the same into the material (6)
Implementation Method 2
Along the force decoupling section (AKE) the screw (2) has a smooth surface (17). The force decoupling section (AKE) decouples the screw (2) in the force decoupling section (AKE) from the porous material (6) and any curable adhesive compound (5)
Implementation Method 3
The applied preload is ensured by the self-expansion of the screw, which is made in particular from a steel material
Data Source
Figure 1
Figure 2~3
AI summary
A screw for screwing into a borehole (4) in a porous material (6) comprises a core (12) with an insertion end (13) and a central longitudinal axis (15), a cutting thread (16) formed integrally with the core (12) and extending along a cutting thread section (ASG) arranged on the insertion end (13) for cutting the same into the material (6), a preload section (AVG) formed integrally with the core (12) for preloading the screw (2) in the material (6), and a force decoupling section (AKE) with a smooth surface (17) arranged along the central longitudinal axis (15) between the cutting thread section (ASG) and the preload section (AVG).