Metal-Plastic Expansion Anchor Knot Formation

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Solution Overview

Problem

Existing expansion anchors with metal and plastic components lack an optimal combination of expansion behavior, particularly in varying building materials, leading to inefficiencies in anchoring and stability.

Innovation Solution

A metal-plastic expansion anchor design featuring plastic and metal expansion legs, where the metal legs are thinner in the circumferential direction and expand by twisting around the longitudinal axis, forming a knot-like structure that adapts to building material cavities, enhancing anchoring in both solid and hollow materials.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If expansion legs are made uniformly thick in the circumferential direction, then structural stability is maintained, but adaptability to different building material cavities deteriorates

Engineering Contradiction:
Improvestructural stabilityVSAvoidadaptability to building material cavities
Core Design Contradiction:
Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The expansion legs are designed with non-uniform thickness in the circumferential direction: thicker at the rear end for structural stability and anchoring strength, and thinner at the front end for adaptability and knot formation. This local variation in geometry allows the same component to fulfill multiple functional requirements simultaneously.

Inventive Principle:
Principle #3Local quality

2Adaptability or versatility

If expansion legs are made more flexible for better adaptation, then anchoring in hollow materials improves, but load-bearing capacity deteriorates

Engineering Contradiction:
Improveanchoring in hollow materialsVSAvoidload-bearing capacity
Core Design Contradiction:
Adaptability or versatilityVSStrength

Solution Approach 1:

The expansion legs exhibit spatially varying flexibility through their thickness distribution: the thinner front portion provides flexibility for adaptation to cavity shapes and knot formation, while the thicker rear portion maintains sufficient strength for load-bearing. This local differentiation resolves the contradiction between flexibility and strength.

Inventive Principle:
Principle #3Local quality

3Force

If metal expansion legs are thicker in the circumferential direction, then expansion force is improved, but knot formation capability deteriorates

Engineering Contradiction:
Improveexpansion forceVSAvoidknot formation capability
Core Design Contradiction:
ForceVSEase of operation

Solution Approach 1:

The metal expansion legs are designed with thickness variation along their length: thicker at the rear to provide sufficient expansion force against the cavity walls, and thinner at the front to enable easy bending and knot formation. This local differentiation allows both force generation and operational flexibility.

Inventive Principle:
Principle #3Local quality

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 design improves anchoring stability and adaptability, providing secure hold in diverse building materials through a combination of radial expansion and knot formation, ensuring effective anchoring in both solid and hollow structures.

Implementation Method 1

the at least one second expansion leg made of metal—in particular together with the at least one first expansion leg made of plastic and optionally further first and/or second expansion legs—forms a type of knot

Methodology Applied
Scientific EffectRadial expansion:

Implementation Method 2

In a solid building material, the expanded expansion legs of the metal sleeve anchor the expansion anchor by form fit and/or force fit

Methodology Applied
Scientific EffectForm fit:

Implementation Method 3

For expansion, the expansion legs of the expansion anchor according to the invention are loaded radially outwards away from the longitudinal axis or at least with a component radially outwards by inserting a preferably pin-shaped expansion element

Methodology Applied
Scientific EffectRadial loading:

Implementation Method 4

During expansion, the expansion legs are pivoted outwards, for example, about a pivot axis tangential to the expansion anchor or to the longitudinal axis of the expansion anchor

Methodology Applied
Scientific EffectPivoting:

Implementation Method 5

the expanded expansion legs of the metal sleeve anchor the expansion anchor by form fit and/or force fit

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP4596900A1Expansion dowel
Publication Date: 2025.08.06 FISCHERWERKE ARTUR FISCHER GMBH & CO KG
  • EP4596900A1 patent drawingFigure 1~2
  • EP4596900A1 patent drawingFigure 3~4
  • EP4596900A1 patent drawingFigure 5

AI summary

The invention relates to a metal-plastic expansion anchor (1) with a plastic base part (2) having a transverse longitudinal slot (6) which divides the base part (2) into two opposing first plastic expansion legs (7) extending in a longitudinal direction (L) of the expansion anchor (1). According to the invention, an insert (3) punched from sheet metal and bent by 180° in a longitudinal center is arranged in the longitudinal slot (6), said insert having two pairs of opposing second metal expansion legs (11). The second metal expansion legs (11) are thin in a circumferential direction (U) of the expansion anchor (1), whereby they can be easily twisted, i.e., wound around a longitudinal axis (A) of the expansion anchor (1) and formed together with the first expansion legs (7) into a node which has a good hold by engaging behind in a cavity of a hollow building material.