Spreading Plug with Offset Slots and Rotary Blades
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Solution Overview
Problem
Existing expansion dowels face insufficient pull-out resistance in porous masonry or hollow bricks with irregular boreholes, as they struggle to adapt to the varying shapes and provide even anchoring due to limited expansion directions and material deformation.
Innovation Solution
The dowel jacket features offset longitudinal slots forming different main expansion directions, with overlapping sections and annular grooves, allowing for precise and resilient adaptation to boreholes, and includes radially movable rotary blades for anti-rotation and even force distribution, ensuring robust anchoring even in unfavorable borehole conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional expansion dowels with limited expansion directions are used, then the device complexity is low, but the pull-out resistance is insufficient in porous masonry or hollow bricks with irregular boreholes
Solution Approach 1:
The dowel jacket is divided into multiple expansion elements (at least two) with different main expansion directions, creating segmented expansion zones that independently adapt to borehole irregularities. This segmentation allows each element to expand in its optimal direction, significantly improving pull-out resistance in porous and hollow materials without requiring excessive overall complexity
Solution Approach 2:
The expansion elements are designed with asymmetric slot arrangements relative to the dowel axis, with each element having different main expansion directions. This asymmetric configuration enables the dowel to adapt to the asymmetric irregularities commonly found in hollow bricks and porous masonry, maximizing anchoring effectiveness while maintaining reasonable structural complexity
2Adaptability or versatility
If the dowel jacket is made of deformable material to adapt to borehole irregularities, then the adaptability improves, but the anchoring precision and force distribution become uneven
Solution Approach 1:
By segmenting the dowel into distinct expansion elements with defined expansion directions, the patent achieves both adaptability to borehole irregularities and precision in force distribution. Each segment deforms independently to match local borehole geometry while maintaining controlled expansion patterns, preventing the uneven force distribution that occurs with fully deformable continuous jackets
Solution Approach 2:
Different regions of the dowel jacket are designed with different local properties - each expansion element has specific slot orientations and geometries tailored to its location and function. This local quality approach allows the dowel to adapt to varying borehole conditions at different positions while maintaining precise anchoring characteristics in each local zone
3Reliability
If a single expansion direction is used in the dowel jacket, then the device complexity is low, but the anchoring effectiveness in unfavorable borehole conditions is reduced
Solution Approach 1:
The asymmetric arrangement of expansion elements with different main expansion directions creates a reliable anchoring system that handles unfavorable borehole conditions from multiple angles. The asymmetric slot patterns ensure that at least some expansion elements always have an effective expansion direction, regardless of borehole irregularities, thereby maintaining high anchoring reliability without excessive complexity
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 enhances retention values by evenly distributing expansion force across multiple directions, adapting to irregularities, and preventing dowel rotation, thus providing superior anchoring and resistance to pulling out in various building materials.
Implementation Method 1
the rotary blades expand radially outward to anchor the dowel in the borehole and prevent rotation
Implementation Method 2
allowing for precise and resilient adaptation to boreholes, and includes radially movable rotary blades for anti-rotation and even force distribution
Data Source
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AI summary
The object of the invention is a spreading plug which preferably comprises plastic and has a plurality of slots (26) in the plug cover, between which slots (26) spreading segments are formed which are spread outward against the wall of the drilled hole when a screw or another spreading element is screwed into the central insertion channel (16) of the plug. In order to obtain a plurality of spreading regions which are distributed over the axial plug length, for the purpose of a more uniform spreading action, a plurality of slot arrangements (26, 28) are provided which are arranged offset with respect to one another both in the circumferential direction and in the axial direction. Preferably, a first slot (26) which extends over the diameter of the plug is provided over a part length of the shaft and a further continuous slot (28) is provided, offset in the circumferential direction by 90°, over the remaining part of the plug length as far as the plug base (14). Here, the two slot pairs (26, 28) overlap one another in the central region. Moreover, preferably window slots which lie opposite one another are provided in the plug base region (14), in which window slots rotary vanes can move which are integrally formed on the plug sleeve by way of their plug-base-side end via a joint, spread outwards when the screw is screwed in and ensure both rotational securing and securing against being pulled out axially.