Expansion Plug Stepped Cut-Outs Locking Knot

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Solution Overview

Problem

Existing expansion plugs fail to provide a stable and durable fixation for both hollow and solid construction elements, particularly in materials like bricks and paper-based plasterboards, due to inadequate shape adaptation and locking mechanisms.

Innovation Solution

The expansion plug features expansion arms with stepped cut-outs and a tapered sleeve, a flange with longitudinal ribs, and connectors of varying width, allowing it to change shape and form a locking knot when the expansion-shell bolt is screwed in, ensuring secure fixation without damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the expansion plug has a considerable length to ensure stable fixation in hollow elements, then the fixation stability is improved, but the guidance precision of the expansion-shell bolt deteriorates

Engineering Contradiction:
Improvefixation stabilityVSAvoidguidance precision
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The expansion plug features connectors with varying widths along its length - wider connectors near the flange for precise bolt guidance, and narrower connectors near the tapered sleeve for effective knot formation. This local variation in connector width optimizes both guidance precision and fixation stability at different positions of the plug.

Inventive Principle:
Principle #3Local quality

2Reliability

If the expansion plug forms a blocking knot to lock its position in solid elements, then the fixation reliability is improved, but the ability to unscrew the expansion-shell bolt deteriorates

Engineering Contradiction:
Improvefixation reliabilityVSAvoidbolt removal ease
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The expansion plug is designed to form a blocking knot that locks the expansion-shell bolt in place after installation, providing secure fixation. The knot forms automatically as the plug expands within the hollow element, creating a preliminary locking action that maintains fixation reliability while still allowing bolt removal when needed.

Inventive Principle:
Principle #10Preliminary action

3Manufacturing precision

If the connectors near the flange are wider to guide the expansion-shell bolt precisely, then the guidance precision is improved, but the device complexity increases

Engineering Contradiction:
Improveguidance precisionVSAvoidconnector width variation
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The expansion plug is segmented into multiple connectors along its length, each with optimized width for its specific function. The segmentation allows wider connectors at the flange end for guidance and narrower connectors at the sleeve end for knot formation, with each segment independently optimized for its local requirement.

Inventive Principle:
Principle #1Segmentation

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 enables a stable and durable fixation of both hollow and solid construction elements, allowing for precise guidance of the expansion-shell bolt and enabling the formation of a blocking knot that maintains the plug's position securely, even with considerable length, facilitating easy assembly and disassembly.

Implementation Method 1

Expansion arms are connected to each other in the circumferential direction by means of a elastic material. The elastic material is interrupted by a few spiral spaced slits.

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3315794B1An expansion plug
Publication Date: 2020.01.29 KOELNER RAWLPLUG IP SP ZOO
  • EP3315794B1 patent drawingFigure 1~4

AI summary

An expansion plug for fixing on hollow and solid construction elements, is designed for fixing in construction elements having voids inside, e.g. in bricks or paper-based plasterboards, as well as in solid construction elements made e.g. of concrete or silica. An expansion plug for fixing on hollow and solid construction elements with expansion arms placed along the plug and with stepped cut-outs along the plug, and the inlet of the plug is provided with a flange and longitudinal ribs are provided at the flange, while the opposite end of the plug is a tapered sleeve. The expansion plug characterized in that its length L to external diameter d ratio is from 6 to 10, and the cut-outs (2) are provided with connectors (7).