Segmented Expansion Sleeve Geometry for Higher Pull-Out Resistance
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Solution Overview
Problem
Existing expansion anchors face challenges in achieving optimal expansion behavior and high pull-out resistance when anchored in fastening bases, requiring improved geometry and materials to reduce installation effort and enhance holding capacity.
Innovation Solution
The expansion anchor features a metal anchor shaft with a radially expanding sleeve, designed with slots and recesses that allow for controlled expansion, where the sleeve is partially or completely bent around the shaft, and includes a conical expansion element that expands radially, optimizing the expansion behavior and interaction with the borehole wall for increased holding values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the expansion sleeve has a simple cylindrical geometry without slots or recesses, then the manufacturing process is simple, but the expansion behavior is poor and pull-out resistance is low
Solution Approach 1:
The expansion sleeve is divided into multiple expansion segments by longitudinal slots, allowing each segment to expand independently and create effective contact with the borehole wall. This segmentation enables the sleeve to achieve high pull-out resistance through distributed frictional and positive connections while maintaining a relatively simple overall structure.
Solution Approach 2:
Recesses are introduced at specific locations (front and rear ends) of the expansion segments to create localized expansion points. These local modifications enable controlled expansion behavior at critical positions, improving the anchor's holding capacity without requiring complex geometry throughout the entire sleeve.
2Strength
If the expansion sleeve is made stiff to maintain structural integrity, then the anchor shaft strength is maintained, but the insertion effort into the borehole increases
Solution Approach 1:
The expansion sleeve transitions from a rigid state during insertion to a flexible expanded state during anchoring. The slots and recesses enable the sleeve to deform dynamically during expansion while maintaining structural integrity when expanded, reducing insertion effort without sacrificing strength.
Solution Approach 2:
By dividing the sleeve into segments through slots, the structure gains flexibility during insertion and expansion while maintaining overall structural integrity. The segmented design allows easier compression during insertion while providing robust anchoring when expanded.
3Strength
If the expansion segments have uniform thickness throughout, then the manufacturing process is simple, but the expansion behavior is not optimized for high holding values
Solution Approach 1:
The sleeve thickness is varied locally with recesses at the front and rear ends of expansion segments. This non-uniform thickness creates optimized expansion behavior at critical positions, improving holding capacity through controlled expansion points while adding minimal manufacturing complexity through localized forming operations.
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 allows for easier installation with reduced effort and enhances the expansion anchor's pull-out resistance by creating a positive and frictional connection with the borehole wall, increasing the load-bearing capacity and holding values.
Implementation Method 1
The expansion element is designed such that the expansion sleeve expands radially when it is pushed longitudinally onto the expansion element
Implementation Method 2
creating a positive and frictional connection with the borehole wall, increasing the load-bearing capacity and holding values
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
The invention relates to an expansion anchor (1) for anchoring in a concrete base. The expansion anchor (1) comprises a slotted expansion sleeve (14) which has local expansions (19) in slots (18) in a front section (15) and recesses (23) in expansion segments (20) at the same level. The local expansions (19) and the recesses (23) improve the expansion of the expansion segments (20) of the expansion sleeve (14) in the base.