Segmented Plastic Dowel With Pivoting Expansion Elements
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Solution Overview
Problem
Existing plastic dowels for fastening window frames to masonry are difficult to produce with smaller nominal diameters and lack efficient expansion mechanisms for enhanced anchoring.
Innovation Solution
A dowel design featuring expansion elements and return elements that are arranged between each other, with the expansion elements pivoting outward and the return elements deforming to provide mechanical stability and locking mechanism, allowing for effective anchoring in drilled holes, even with smaller diameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional smooth-surfaced dowel sleeves are used, then production is simpler, but anchoring effectiveness in smaller diameters is insufficient
Solution Approach 1:
The dowel sleeve is segmented into multiple expansion elements (at least two) arranged at different angular positions around the circumference. Each expansion element can independently expand outward when the expansion element is screwed in, providing distributed anchoring force that improves reliability in smaller diameters while maintaining manufacturability through modular design
Solution Approach 2:
The dowel sleeve transitions from a static smooth-surfaced structure to a dynamic structure with expansion elements that can change their radial position. The expansion elements are designed to expand outward in the radial direction when actuated by the expansion element, enabling the dowel to adapt its anchoring characteristics based on installation conditions
2Reliability
If expansion elements are added to improve anchoring, then anchoring effectiveness increases, but device complexity increases
Solution Approach 1:
The expansion elements are integrally formed with the dowel sleeve as a single piece, eliminating the need for separate components. The at least two expansion elements are arranged at different angular positions around the circumference of the dowel sleeve, providing effective anchoring while maintaining a relatively simple monolithic structure that reduces manufacturing complexity
Solution Approach 2:
The expansion elements are strategically positioned at specific angular locations around the circumference rather than uniformly distributed. This localized arrangement provides effective anchoring at critical positions while minimizing the overall complexity of the dowel structure
3Reliability
If multiple expansion elements are used, then locking mechanism improves, but manufacturing difficulty increases
Solution Approach 1:
The expansion elements are pre-formed as integral parts of the dowel sleeve during manufacturing, with their geometry and positioning predetermined. This preliminary formation allows the complex multi-element structure to be manufactured as a single piece, improving the locking mechanism while avoiding the need for complex assembly processes
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 dowel achieves improved anchoring and mechanical stability in masonry, allowing for efficient expansion and locking within the hole, enhancing the holding effect and ease of production with smaller diameters.
Implementation Method 1
The expanding elements are pressed against the wall of the dowel hole and the edges of the expanding elements cause the dowel to lock to the hole
Implementation Method 2
The return elements, which contribute to the stability of the dowel sleeve, are designed to be bendable relative to the dowel sleeve
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The dowel comprises a dowel sleeve at interior extending in the longitudinal direction for the admission of a spreading element, an expanding range, which has multiple expanding elements (6), which are movable outward when expanding the dowel sleeve and multiple return elements (7) are arranged. The return elements are movable outwards when expanding the dowel sleeve.