Expansion Anchor Tongue Angles for Cracked Concrete Grip
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Solution Overview
Problem
Conventional expansion anchors face limitations in dimensioning due to the interplay between external and internal friction, which restricts the choice of expansion angles, particularly in cracked concrete, leading to potential premature pull-out without adequate anchoring.
Innovation Solution
The expansion anchor features different tongues with varying bevel angles, where the expansion tongue has a flat angle for initial fixation and the anchor tongue has a steep angle for increased expansion after cracking, allowing larger angles without excessive internal friction, and all parts are integrated into the expansion sleeve for low production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the expansion angle is increased to enable effective re-expansion in cracked concrete, then the anchoring capability in cracked substrates is improved, but the internal friction becomes greater than external friction causing premature pull-out
Solution Approach 1:
The expansion sleeve is segmented into multiple tongues (expansion tongues and anchor tongues) that can be independently dimensioned with different angles. This segmentation allows the anchor tongue to have a larger angle for cracked concrete anchoring while the expansion tongue maintains a smaller angle to control internal friction during installation.
Solution Approach 2:
Different regions of the expansion sleeve are given different geometric properties - the expansion tongue has a smaller angle suited for initial fixation with controlled friction, while the anchor tongue has a larger angle optimized for anchoring in cracked concrete. This local differentiation resolves the contradiction between needing large angles for crack anchoring and small angles for controlling installation friction.
2Device complexity
If a single expansion angle is used for both initial fixation and crack anchoring, then the device structure is simplified, but the anchoring performance in cracked concrete is insufficient
Solution Approach 1:
The expansion sleeve is divided into functionally distinct tongues with different angles. The anchor tongues are specifically designed with larger angles to engage effectively with cracked concrete, while expansion tongues use smaller angles. This segmentation enables optimized performance for both initial fixation and crack anchoring without excessive structural complexity.
Solution Approach 2:
The expansion sleeve serves multiple functions through its different tongues: the expansion tongues handle initial fixation with controlled friction, while the anchor tongues provide specialized anchoring in cracked concrete. This multi-functionality allows a single component to address both installation and ultimate load-bearing requirements in varied substrate conditions.
3Adaptability or versatility
If the expansion tongue and anchor tongue are dimensioned independently with different angles, then the anchoring versatility is improved, but the manufacturing complexity increases
Solution Approach 1:
The expansion tongues and anchor tongues are merged into a single integrated expansion sleeve component. This consolidation allows both sets of tongues with different angles to be manufactured together as one piece, reducing assembly complexity and production costs while maintaining the versatility benefits of having differently angled tongues for various substrate conditions.
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 enables effective anchoring in cracked concrete with reduced internal friction during installation and enhanced expansion capabilities, providing a versatile and cost-efficient solution for various substrate conditions.
Implementation Method 1
the interplay between external friction—i.e., the friction between the expansion sleeve and the borehole wall—and internal friction—i.e., the friction between the expansion sleeve and the anchor bolt
Data Source
Figure 1~4
Figure 5~8
AI summary
The invention relates to an expansion bolt according to the preamble of claim 1. Such an expansion bolt is equipped with an anchoring bolt (10) and an expansion sleeve (30) which surrounds the anchoring bolt. According to the invention, the expansion sleeve has an expansion tongue (31) and an anchoring tongue (32), and the anchoring bolt has an inclined expansion section (21) facing the rear for radially pushing the expansion tongue and an inclined anchoring section (22) facing the rear for radially pushing the anchoring tongue, wherein the inclined anchoring section runs more steeply than the inclined expansion section at least in some regions.