Expandable Anchor Sleeve Preload for Low-Force Hole Insertion
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Solution Overview
Problem
Existing expansion anchors require significant force to be introduced into anchor holes and lack efficient self-expansion mechanisms for secure anchoring in stone, masonry, or concrete.
Innovation Solution
An expansible anchor design featuring a prestressed expansion sleeve that expands automatically upon release from a prestressing device, allowing for low-force insertion and subsequent self-expansion for secure fixation, with an axially connected expansion body and a conical nut for axial force transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional expansion anchors are inserted into anchor holes, then anchoring function is achieved, but significant insertion force is required
Solution Approach 1:
The expansion sleeve is pre-expanded before installation and held in this expanded state by a pre-tensioning device. This preliminary expansion action allows the anchor to be inserted into the anchor hole with minimal force, as the expansion sleeve is already in its functional expanded configuration before insertion.
Solution Approach 2:
The expansion sleeve's diameter is changed from an expanded state during storage to a compressed state during insertion, and then back to the expanded state after installation. This parameter change allows the anchor to be inserted easily while maintaining its anchoring function.
2Ease of operation
If expansion sleeve is pre-expanded for easy insertion, then insertion force is reduced, but additional anchoring strength is required to maintain expansion
Solution Approach 1:
The pre-tensioning device automatically maintains the expansion sleeve in its expanded state without requiring additional anchoring strength. The spring element provides continuous pre-tension to keep the expansion sleeve expanded, eliminating the need for separate anchoring mechanisms.
Solution Approach 2:
The pre-tensioning device uses a spring element that dynamically adjusts to maintain the expansion sleeve in its expanded state. The spring provides continuous force to counteract any tendency of the expansion sleeve to collapse, ensuring stable anchoring without additional strength requirements.
3Reliability
If expansion anchor uses traditional expansion mechanism, then anchoring function is achieved, but complex pre-expansion devices are required
Solution Approach 1:
The pre-expansion function is extracted from the main anchor body and implemented as a separate pre-tensioning device with a spring element. This separation simplifies the overall design by dedicating specific components to specific functions: the spring element handles pre-expansion, while the expansion body handles final anchoring.
Solution Approach 2:
The anchor is segmented into distinct functional components: the expansion body, the expansion sleeve, and the pre-tensioning device with spring element. Each segment performs a specific function, making the overall system more manageable and easier to manufacture while maintaining reliable anchoring function.
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
Enables easy, low-force insertion and secure anchoring in anchor holes, with the expansion sleeve expanding to firmly hold the anchor in place, absorbing forces effectively without requiring additional anchoring strength.
Implementation Method 1
the spring element is supported by a washer (18) on a screw head (19) of the screw (2)... the spring element (17) has a preload and acts on the expansion sleeve (5) in the longitudinal direction or the axial direction
Data Source
Figure 1~2
AI summary
The invention proposes to hold the free ends of expansion tabs (10) of an expansion sleeve (5) of an expansion anchor (1) in an inwardly directed annular step (11) at an end face of an expansion body (4) facing the expansion sleeve (5), so that the expansion tabs (10) spring outwards and secure the expansion sleeve (5) in an anchor hole when the expansion tabs (10) are released from the annular step (11). To release the expansion tabs (10), the expansion anchor (1) has a tubular push and pull element (14) which has a disc spring-like flange that presses the expansion sleeve (5) in the direction of the expansion body (4).