Self-Drilling Wall Plug Cup Structure for Guided Screw Anchorage
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Solution Overview
Problem
Existing self-drilling wall plugs lack efficient guidance and anchoring mechanisms for screws, leading to uneven cut-through resistance and potential slippage during insertion into lightweight building materials.
Innovation Solution
A self-drilling wall plug design featuring a cone-shaped cup with asymmetric cut-through resistance, a non-coaxial rotational axis, and pivotable wall portions, which guides screws to exit on one side and provides enhanced anchorage by deflecting the screw tip to a side with lower resistance, and includes cutting teeth for improved cutting efficiency and debris conveyance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a self-drilling wall plug is used for screwing into lightweight building materials, then the wall plug can be installed directly without pre-drilling, but the screw lacks efficient guidance and anchoring mechanisms leading to uneven cut-through resistance and potential slippage
Solution Approach 1:
The cup structure is designed with asymmetric wall thickness where the first side has greater wall thickness than the second side. This creates different cut-through resistance on different sides of the cup, providing localized quality variation that guides the screw tip to break through at the intended location while maintaining overall structural integrity for direct installation
Solution Approach 2:
The cup is designed with non-coaxial rotational axes - the rotational axis of the cup is offset from the rotational axis of the wall plug body. This asymmetric geometry ensures that when the screw penetrates the cup, it is systematically deflected to exit on one side rather than continuing straight, providing reliable guidance and preventing slippage during insertion
2Reliability
If the cup has asymmetric wall thickness to provide different cut-through resistance, then the screw can be systematically guided to break through on the side with smaller wall thickness, but the structural complexity of the cup increases
Solution Approach 1:
Instead of making the entire cup structure complex, only specific regions (the first and second sides of the cup) have different wall thicknesses. This localized differentiation provides the necessary guidance function while keeping the rest of the cup structure simple and manufacturable
Solution Approach 2:
The asymmetric wall thickness design creates a natural guidance mechanism where the screw tip is directed toward the thinner side. This simple asymmetric geometry achieves systematic screw guidance without requiring complex internal structures, mechanisms, or multiple components
3Reliability
If the rotational axis of the cup is non-coaxial with the rotational axis of the wall plug, then the screw is deflected to one side for better guidance, but the manufacturing precision requirements increase
Solution Approach 1:
The design embraces the non-coaxial arrangement as a functional feature rather than treating it as a deviation. The asymmetric positioning of the cup's rotational axis relative to the wall plug's rotational axis is intentionally designed to provide systematic screw deflection, turning a potential manufacturing challenge into a reliable guidance mechanism
4Productivity
If cutting teeth are added to the front end of the wall plug, then cutting efficiency and debris conveyance are improved, but the device complexity increases
Solution Approach 1:
The cutting teeth are integrated directly into the front end structure of the wall plug body, merging the cutting function with the insertion element. This combination eliminates the need for separate cutting tools or complex multi-component front ends, achieving improved cutting efficiency while maintaining relatively simple device structure
Data Source
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AI summary
The invention relates to a self-drilling wall plug (1) for screwing into lightweight building materials, in particular into plaster walls, having a sleeve-shaped plug body (4) surrounded by a cutting thread (2), a flange (6) on the rear side, at least one cutting tooth (18, 20) like a milling tool in the region of its front end (10) comprising a tip (12), an inner profile formed along an inner wall (30) by a plurality of longitudinal ribs (32), into which the thread of a fixing element cuts, and in its flange (6) a recess (28) for engaging a driving tool, wherein a cup (38) for receiving the front end (10) of a fixing element penetrating the wall plug (1) is provided in the region of the tip (12).