Concrete Screw Thread Geometry for Low Torque and Load Bearing
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Solution Overview
Problem
Existing concrete screws face challenges in balancing setting behavior and load-bearing capacity, with conventional designs often requiring high torque for screwing and inadequate distribution of load.
Innovation Solution
A concrete screw design featuring a screw head with a tool seat and a shank with a threaded section that includes a cutting section with a larger diameter and thread width than the supporting section, allowing for easy screwing while maintaining good load-bearing capacity through a balanced thread geometry and notch features.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the diameter and width of the cutting thread are increased to improve insertion ease, then the torque required for screwing increases, but the load-bearing capacity decreases
Solution Approach 1:
The threaded section is segmented into a cutting section with larger diameter and width for easy insertion, and a bearing section with smaller diameter for high load-bearing capacity. This segmentation allows each section to be optimized for its specific function without compromising the other.
Solution Approach 2:
Different sections of the thread have different local qualities: the cutting section has larger diameter and width (at least 10% greater thread width) to reduce insertion torque, while the bearing section has smaller diameter to maximize load-bearing capacity. This local differentiation resolves the contradiction between ease of insertion and load-bearing strength.
2Force
If the thread width in the cutting section is increased to reduce insertion torque, then the friction increases, but the setting behavior deteriorates
Solution Approach 1:
The thread is segmented into cutting and bearing sections with distinct functions. The cutting section has increased width to reduce insertion torque, while the bearing section has optimized width for proper setting behavior and friction control.
Solution Approach 2:
The cutting section has locally increased thread width (at least 10% greater than bearing section) to reduce insertion torque, while the bearing section maintains appropriate thread dimensions for optimal setting behavior and friction characteristics.
3Strength
If the diameter of the bearing section is decreased to improve load-bearing capacity, then the transition area complexity increases, but the manufacturing difficulty increases
Solution Approach 1:
The threaded section is clearly segmented into cutting and bearing sections with a defined transition area. This segmentation allows for systematic manufacturing processes that can handle the diameter change while maintaining production efficiency.
Solution Approach 2:
The bearing section has locally reduced diameter to maximize load-bearing capacity, with a transition area that smoothly connects to the cutting section. This local differentiation achieves high strength while remaining manufacturable.
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 design achieves low torque for screwing into drilled holes and enhanced load-bearing capacity by reducing friction and distributing load effectively across the internal thread, resulting in improved setting behavior and load-bearing performance.
Implementation Method 1
As they are screwed into the borehole wall, they cut an internal thread that is complementary to the screw's thread. In this context, 'cutting' refers less to cutting through and more to abrasion, grinding, or grinding.
Implementation Method 2
under tensile load, the bearing thread bears against the flanks of the cut internal thread due to the deformation of the screw or the anchoring base, resulting in good load distribution
Implementation Method 3
the bearing thread rubs only minimally against the thread flanks of the cut internal thread when the screw is driven in
Data Source
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AI summary
The invention relates to a concrete screw (1) having a screw head (2) and a shaft (3) on which a thread section (7) is formed having a core (8) and a thread path (9). The thread section (7) comprises a cutting section (10) for cutting into a mineral anchoring base, and a support section (11), wherein the diameter (D10) of the cutting section (10) is a maximum of 5% larger than the diameter (Du) of the support section (11). According to the invention, in order that the concrete screw (1) is easy to screw in while having good supporting behaviour, at least one part of the thread path (9) has a width (Bio) in the cutting section (10) measured in the direction of the longitudinal axis (L), which width is at least 10% larger than a width (Bn) in the support section (11).