Expansion Anchor With Twisted Conical Section
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Solution Overview
Problem
Conventional multi-part expansion anchors require high setting energy due to the radial expansion tabs resting against conical surfaces, leading to increased friction and difficulty in anchoring in subsoil.
Innovation Solution
The expansion anchor design features a twisted conical section with an odd number of elements on one part and an even number on the other, minimizing friction and reducing setting energy by allowing selective contact, and incorporating a polygonal cross-section with curved edges to facilitate easier expansion and prevent unintentional pulling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the expansion tabs rest against the conical surfaces between the edges, then the expansion anchor achieves radial expansion, but a high level of setting energy is required due to increased friction
Solution Approach 1:
The expansion body is twisted in the longitudinal axis at the conical section, creating an asymmetric configuration where the number of edges with even parity differs from the number of expansion tabs with odd parity. This asymmetric arrangement ensures selective contact between the expansion tabs and conical surfaces, minimizing the friction surface area and reducing the setting energy required for radial expansion while maintaining adequate expansion capability
2Use of energy by moving object
If the expansion body is twisted with different numbers of elements, then friction is minimized and setting energy is reduced, but the conical section requires a complex polygonal cross-section with curved edges
Solution Approach 1:
The conical section features a polygonal cross-section with an asymmetric number of edges that does not match the number of expansion tabs, creating selective contact zones. This asymmetric geometry, combined with curved edges, reduces the friction surface area while maintaining the functional requirement for radial expansion
Solution Approach 2:
The edges of the conical section are curved rather than straight, creating a more complex geometry that facilitates easier expansion by distributing contact stresses more effectively while maintaining the reduced friction surface area needed for lower setting energy
3Use of energy by moving object
If the friction surface area is minimized, then setting energy is reduced, but the security against the expansion body being pulled through the expansion sleeve decreases
Solution Approach 1:
The gaps created between the expansion sleeve and the polygonal conical section of the expansion body, which result from the selective contact arrangement, are utilized to allow drill dust to penetrate into the gap. This penetrated drill dust increases friction between the components towards the end of the insertion process, providing security against pull-through while maintaining low initial setting energy
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 reduces the initial setting energy required, enhances pull-out loads, and provides security against the expansion body being pulled through, while allowing drill dust to increase friction for added stability, making it suitable for various substrates including soft materials like aerated concrete.
Implementation Method 1
By pulling the expansion body into the expansion sleeve, this is expanded radially and the expansion anchor is anchored in the subsoil
Implementation Method 2
This minimizes the friction surface and thus the initial internal friction, as the integration of the friction stresses over the friction surface between the expansion body and the expansion sleeve
Data Source
Figure 1~4
Figure 5~7
AI summary
A multi-part expansion anchor (11) comprises, as a first part, an expansion sleeve (31) which has as its elements several expansion flaps (35) separated from one another by longitudinal slots (34), and as a second part, an expansion body (21) which can be inserted into the expansion sleeve (31) and has a conical section (22) for radially expanding the expansion sleeve (31). The conical section (22) has as its elements edges (24) extending in the longitudinal axis (13). One part of the expansion anchor (11) has an even number of the corresponding elements, and the other part of the expansion anchor (11) has an odd number of the corresponding elements.