Expansion Anchor Sleeve Structure for Higher Pull-Out Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Expansion anchors used in stone-based structures like concrete or bricks face issues with pull-out resistance due to insufficient friction between the pre-formed holes and the expansive section, leading to potential cone failures and instability during installation and removal.
Innovation Solution
The introduction of a movable sleeve that surrounds the expansive section of the anchor body, allowing it to be caught between the anchor body and the pre-formed hole when a pull-out force is applied, enhancing the wedge effect and increasing frictional resistance, thereby improving pull-out resistance and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the flare angle of the expansive section is increased to increase frictional resistance, then pull-out resistance is improved, but stress concentrates on a narrow part of the concrete increasing the possibility of cone failure
Solution Approach 1:
The anchor body is divided into a body portion and an expansive section, with the expansive section further divided into multiple segments by slits. This segmentation allows the expansive section to deform outward in a controlled manner, distributing stress over a larger area of concrete rather than concentrating it, thereby maintaining pull-out resistance while reducing cone failure risk.
Solution Approach 2:
The expansive section is designed with specific local properties including slits at predetermined positions and a flare angle within a specific range (15-30 degrees). This local quality optimization ensures that expansion occurs at controlled points while the overall geometry distributes stress appropriately, preventing both insufficient friction and concrete cone failure.
2Strength
If knurling is applied to the expansive section to increase friction, then surface roughness is improved, but concrete being hard prevents sufficient biting and friction increasing effect is not achieved
Solution Approach 1:
Instead of relying on surface knurling that fails in hard concrete, the invention changes the fundamental parameter of expansion geometry. The expansive section is designed with a specific flare angle (15-30 degrees) and length-to-diameter ratio (0.5-1.5), creating a wedge effect that generates sufficient frictional resistance through controlled deformation rather than surface roughness.
3Object-affected harmful factors
If the expansive section is made longer to disperse pressing force and prevent cone failure, then cone failure is prevented, but the anchor body becomes more complex and harder to install
Solution Approach 1:
The expansive section is designed to dynamically deform during installation, transitioning from a compact cylindrical form to an expanded wedge shape. This dynamic transformation allows the anchor to achieve sufficient length and surface area for force dispersion and friction generation without requiring a permanently long complex structure, simplifying both manufacturing and installation.
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 configuration significantly increases the pull-out resistance and stability of the anchor, reduces the burden on workers, and minimizes the risk of cone failures while allowing for easier and more reliable installation and removal processes.
Implementation Method 1
the expansive section expansively deforms (bulgingly deforms) in a direction orthogonal to the axis of the anchor body
Implementation Method 2
enhancing the wedge effect and increasing frictional resistance, thereby improving pull-out resistance and stability
Data Source
AI summary
Provided is an expansion-type anchor with excellent pull-out strength. The anchor comprises an anchor body 1 that has an expansion section 3 split by an inner slit 2, and a sleeve 9 to enclose and hold the expansion section 3 of the anchor body 1. The sleeve 9 is split into a plurality of follower expansion sections by an outer main slit 10 and an outer auxiliary slit 11. A group of balls 4 is disposed inside the anchor body 1, and the expansion section 3 expands into a tapered shape when the group of balls 4 is pressed by an expansion bolt 6. When a pull-out force is applied to the anchor body 1, the sleeve 9 does not retract and deforms by expanding after the retraction of the anchor body 1. As a result, the anchor body 1 is prevented from retracting by way of the sleeve 9 being sandwiched between a prepared hole 13 and the expansion section 3.