Slotted Expansion Sleeve Anchor for High-Angle Undercuts
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Solution Overview
Problem
Existing undercut anchors face limitations in achieving undercut angles greater than 30 degrees due to drilling technology constraints, and anchors that form their own undercut regions during installation are complex to manufacture.
Innovation Solution
A specially designed undercut anchor with specific dimensional ratios and expansion features allows for installation in holes with undercut angles up to 40 degrees, enhancing pull-out resistance and simplifying manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional undercut anchors are used with drilling technology limitations, then manufacturing is simpler, but undercut angle is limited to 20-30 degrees
Solution Approach 1:
The patent applies parameter changes by optimizing the ratio between the expansion sleeve outer diameter and the threaded rod outer diameter. Specifically, the expansion sleeve outer diameter is designed to be 1.1 to 1.3 times the threaded rod outer diameter, which enables the anchor to achieve undercut angles of 35-45 degrees while maintaining structural integrity and pull-out strength, resolving the contradiction between strength improvement and manufacturing simplicity.
2Strength
If undercut angle is increased to improve pull-out strength, then load capacity increases, but drilling technology constraints prevent angles greater than 30 degrees
Solution Approach 1:
The patent applies dynamics by designing the expansion sleeve with slots that allow it to flex and expand dynamically during installation. The sleeve transitions from a compact state during insertion to an expanded state that creates the undercut region, enabling undercut angles of 35-45 degrees without requiring advanced drilling technology, thus improving load capacity while maintaining adaptability.
Solution Approach 2:
The anchor system performs self-service by creating its own undercut region during installation through the expansion of the sleeve. The expansion feature on the threaded rod pushes the expansion sleeve outward, which in turn creates the undercut region in the hole, eliminating the need for separate undercut drilling operations and enabling greater undercut angles with standard drilling equipment.
3Strength
If expansion sleeve outer diameter is increased to improve pull-out resistance, then anchor holds better, but friction with hole increases during installation
Solution Approach 1:
The patent resolves this contradiction by optimizing the parameter of the expansion sleeve outer diameter to be 1.1 to 1.3 times the threaded rod outer diameter. This specific ratio allows the sleeve to expand sufficiently to create effective undercut angles for high pull-out resistance, while the controlled expansion magnitude minimizes excessive friction during the installation process, enabling smooth insertion followed by effective expansion.
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 anchor achieves improved load capacity and pull-out strength in concrete surfaces with undercut angles between 37 to 43 degrees, offering enhanced performance and simplified manufacturing compared to traditional methods.
Implementation Method 1
The expansion portion 22 of the sleeve 20 extends into the undercut region 12... such movement causes the expansion portion 22 to outwardly deform by cooperating with the expansion feature 18
Data Source
AI summary
An undercut anchor having an at least partially threaded rod portion having an outer thread diameter DROD. The anchor having an expansion feature coupled to the rod portion and an expansion sleeve having an outer diameter DOUTER SLEEVE, an inner diameter DINNER SLEEVE and a wall thickness TSLEEVE. Furthermore, the expansion sleeve has a plurality of circumferentially distributed fingers which are configured to flex outwards when a ramp portion of length LRAMP of each of the respective fingers is forced against the expansion feature during installation of the undercut anchor. The fingers each having a length LFINGER and a distance therebetween of WSLOT.