Slit Expansion Anchor With Ball-Driven Grip Against Cone Failure
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional expansion anchors face limitations in enhancing withdrawal resistance due to cone-type failure, where the concrete around the installation region deteriorates, and the radially expansive portion's excessive expansion leads to reduced stability over time, especially under downward loads.
Innovation Solution
An expansion anchor design featuring a hollow shaft with a radially expansive portion formed by axially elongated slits and a radially expanding action member, such as metal balls, that bulges orthogonally to the axis, providing deep biting engagement with the installation region to increase withdrawal resistance while preventing cone-type failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the radially expansive portion is expanded excessively to increase withdrawal resistance, then the withdrawal resistance is improved, but cone-type failure occurs in the concrete
Solution Approach 1:
The radially expansive portion is divided into multiple segments by longitudinal slits, allowing controlled expansion in multiple directions rather than uniform radial expansion, which reduces the concentration of stress that causes cone-type failure
Solution Approach 2:
The hollow shaft has different structural properties at different locations: the radially expansive portion is weakened by slits for controlled expansion, while other portions maintain full structural integrity to prevent cone-type failure in the concrete
2Stability of the object's composition
If the radially expansive portion is designed to expand sufficiently for high withdrawal resistance, then the anchor stability is improved, but delayed cone-type failure occurs under downward loads
Solution Approach 1:
The expansion anchor uses a dynamic expansion mechanism where the hollow shaft can expand radially through the slits when subjected to load, allowing the structure to adapt and distribute stresses dynamically rather than relying on fixed pre-expansion, preventing delayed failure
3Strength
If the radially expansive portion is positioned at the tip end for maximum expansion effect, then the withdrawal resistance is improved, but the hollow shaft structure becomes weaker
Solution Approach 1:
The hollow shaft is designed with non-uniform properties: the radially expansive portion contains slits for expansion functionality, while the tip end and other portions maintain solid structure for strength, optimizing both withdrawal resistance and structural integrity
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 design achieves high withdrawal resistance and prevents cone-type failure by allowing the radially expansive portion to engage deeply with the concrete, maintaining stability and allowing for adjustable torque to maintain optimal resistance, facilitating easy removal and replacement of the anchor.
Implementation Method 1
a radially expanding action member that pushes the radially expansive portion radially outward in response to pushing action caused by screwing of the bolt into the hollow shaft
Implementation Method 2
providing deep biting engagement with the installation region to increase withdrawal resistance
Data Source
Figure 1A~1F
Figure 2A~2D
Figure 3A~3E
AI summary
An expansion anchor includes a hollow shaft 3 and a bolt 9 to be screwed thereinto from a base end side of the hollow shaft. The hollow shaft 3 is formed, at a portion thereof short of a tip end 3a, with a radially expansive portion 7 which includes slits 6, and a multiplicity of balls 10 are inserted into the radially expansive portion 7. When the bolt 9 is screwed, the balls 10 push against each other and move radially. As a result, the radially expansive portion 7 deforms expansively for securely engaging with a pre-formed hole 2. Even when the radially expansive portion 7 expands, stress does not concentrate at a specific portion of an installation region 1, so that it is possible to provide a high withdrawal resistance while preventing cone-type failure. The management of the withdrawal resistance can be easily performed by screwing the bolt 9) using a wrench with a torque limiter or by screwing the bolt 9 using a torque wrench.