Fastening Element Rotational Stability via Asymmetric Spring Ring
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Solution Overview
Problem
Existing fastening elements for boreholes face challenges in securely anchoring without requiring significant effort or tools, particularly in ensuring rotational stability and preventing unintended co-rotation during expansion, while maintaining a simple and cost-effective design.
Innovation Solution
A fastening element with a conical expansion body and a deformable holding element that radially expands to securely engage with the borehole wall, featuring a load application means like an external thread and a retaining element with elastic deformability to prevent rotation, allowing for easy insertion and secure anchoring without the need for hammers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional fastening element with expansion sleeve and cone nut is used, then anchoring in boreholes is achieved, but rotational stability is insufficient and co-rotation during expansion occurs
Solution Approach 1:
The fastening element is divided into functionally distinct segments: a shaft portion, an expansion body portion with conical geometry, and a holding element (spring ring) with specific opening configurations. This segmentation allows each portion to independently fulfill its specific function - the shaft provides structural support, the conical expansion body enables radial expansion, and the holding element prevents rotation through its opening design that engages with the borehole wall.
Solution Approach 2:
The holding element features asymmetric opening configurations - either a single non-circular opening or multiple openings of different shapes (e.g., rectangular, triangular, trapezoidal) arranged in specific patterns. This asymmetry creates directional engagement with the borehole wall, effectively preventing rotational movement while maintaining structural integrity and simplicity.
2Reliability
If the expansion sleeve outer diameter is increased to improve anchoring, then frictional engagement increases, but insertion effort increases and damage to external thread may occur
Solution Approach 1:
The expansion sleeve is designed with dynamic dimensional characteristics - a smaller outer diameter in the insertion direction to facilitate easy insertion without damaging the external thread, and a larger expanded diameter in the radial direction after expansion to provide sufficient frictional engagement with the borehole wall. The conical expansion body enables this dynamic transition from compact insertion profile to expanded anchoring profile.
Solution Approach 2:
The solution addresses the diameter conflict by utilizing different spatial dimensions - the outer diameter is optimized for insertion (smaller), while the expanded radial dimension provides the necessary frictional engagement (larger). The conical geometry of the expansion body enables this dimensional transformation from axial compactness to radial expansion, effectively resolving the contradiction between insertion ease and anchoring reliability.
3Reliability
If a rotation lock with longitudinal ribs is added to prevent rotation, then rotational stability improves, but device complexity and manufacturing cost increase
Solution Approach 1:
The anti-rotation function is merged with the holding element (spring ring) itself through its opening configuration. The asymmetric or multi-shaped openings inherently provide rotational prevention by engaging with the borehole wall geometry, eliminating the need for separate rotation lock components with longitudinal ribs. This integration maintains rotational stability while simplifying the overall structure and reducing manufacturing complexity.
4Reliability
If the holding element outer diameter is increased to prevent rotation, then rotational stability improves, but the fastening element may not fit into planned boreholes
Solution Approach 1:
The holding element exhibits dynamic dimensional behavior - maintaining a compact outer diameter during insertion to ensure compatibility with planned boreholes, then expanding or deforming after insertion to provide rotational fixation. The spring ring structure enables this transition, allowing the element to adapt its effective diameter based on the operational phase (insertion vs. anchoring).
Solution Approach 2:
The holding element's effective dimensions are changed after insertion through elastic deformation or configuration change. The asymmetric openings engage with the borehole wall to provide rotational prevention without requiring a permanently large outer diameter. This parameter change allows the fastening element to fit into standard boreholes while still achieving rotational stability through the deformed or engaged state of the holding element.
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 fastening element securely anchors in boreholes with minimal effort, prevents co-rotation during load application, and is cost-effectively produced with a simple structure, ensuring reliable frictional engagement without damaging the external thread during insertion.
Implementation Method 1
The holding element can be elastically deformed in order to change its diameter, ie its diameter can be changed reversibly
Implementation Method 2
the fastening element is held in the borehole in a rotationally fixed manner due to the friction occurring between the holding element and the borehole wall
Implementation Method 3
By retracting the expansion body into the expansion sleeve, the expansion sleeve can be radially expanded, i.e. increased in diameter in a radial plane to the longitudinal axis
Data Source
Figure 1~2
Figure 3~4
Figure 5~7
AI summary
The invention relates to a fastening element (1) for anchoring in a drill hole. The fastening element (1) extends along a longitudinal axis (L) and has a shaft (4), on which an expansion sleeve (8) is arranged. Furthermore, a holding element (12) is arranged on the shaft (4), by which the expansion sleeve (8) is frictionally connected to the shaft (4) in a rotationally fixed manner.