Particle-Coated Expansion Anchor for Seizing-Resistant Load Transfer

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Solution Overview

Problem

Existing fastening elements face challenges in achieving efficient and reliable performance, particularly in load-bearing capacity, while also being susceptible to seizing and galling, and require complex manufacturing processes.

Innovation Solution

A fastening element with a coating containing embedded hard particles, where the coating has a lower hardness than the particles, allowing for a multi-stage friction behavior that modifies friction properties, enhancing load-bearing capacity and reducing seizing and galling, and simplifying manufacturing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a coating is applied to the friction surfaces to improve abrasion resistance and load-bearing capacity, then the friction behavior is improved, but the manufacturing complexity increases

Engineering Contradiction:
Improveload-bearing capacityVSAvoidcoating structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies a composite coating material consisting of a polymer matrix with embedded hard particles (such as ceramic or metal particles). This composite structure combines the adhesive properties of the polymer with the abrasion resistance of the hard particles, achieving improved load-bearing capacity and friction behavior while maintaining a relatively simple single-layer coating structure.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The coating is applied selectively to the friction surfaces (bolt and/or expansion element) rather than the entire fastening element. This localized application focuses the enhanced properties where they are most needed for friction and wear resistance, while avoiding unnecessary complexity in non-critical areas.

Inventive Principle:
Principle #3Local quality

2Object-affected harmful factors

If hard particles are embedded in the coating to increase friction and prevent seizing, then the abrasion resistance is improved, but the manufacturing precision requirements increase

Engineering Contradiction:
Improveseizing and gallingVSAvoidparticle embedding
Core Design Contradiction:
Object-affected harmful factorsVSManufacturing precision

Solution Approach 1:

The hard particles are embedded in the coating matrix through a self-leveling process where the coating material is applied in a molten or plastic state, allowing the particles to become naturally embedded as the coating solidifies. This eliminates the need for complex post-processing or precision alignment steps, reducing manufacturing precision requirements while still achieving effective particle embedding for seizure prevention.

Inventive Principle:
Principle #25Self-service

3Reliability

If the coating hardness is lower than the particles to allow particle dominance under stress, then the friction control is improved, but the coating durability may be reduced

Engineering Contradiction:
Improvefriction controlVSAvoidcoating lifespan
Core Design Contradiction:
ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent specifies that the coating material has a hardness parameter that is deliberately lower than the embedded particles, allowing the particles to become dominant under stress conditions and provide consistent friction control. The coating matrix serves as a binding medium that protects the particles while allowing them to engage with the counter surface under load, optimizing both friction control and durability through this hardness parameter relationship.

Inventive Principle:
Principle #35Parameter changes

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 solution provides improved load-bearing capacity, reduced seizing and galling, and enhanced abrasion resistance through variable friction behavior, while simplifying the manufacturing process.

Implementation Method 1

a coating (60) is arranged on at least one of the two friction surfaces (19, 29), in which preferably hard particles (61) are embedded, that the coating (60) has a lower hardness than the particles (61), and that at least a subset of all particles (61) is completely surrounded by the coating (60)

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP3710713B1Fastening element having a particle coating
Publication Date: 2022.09.07 HILTI AG
  • EP3710713B1 patent drawingFigure 1~3
  • EP3710713B1 patent drawingFigure 4~7
  • EP3710713B1 patent drawingFigure 8~9

AI summary

The invention relates to a fastening element, in particular an expansion anchor, having a bolt (10) and a retaining element, which is arranged on the bolt and is intended for introducing tensile forces into the bolt, wherein the bolt has a first metallic frictional surface (19), and wherein the retaining element has a second metallic frictional surface (29, 79), which is assigned to the first frictional surface. The invention makes provision for a coating (60) to be arranged on at least one of the two frictional surfaces, said coating having particles (61), preferably hard particles, embedded in it.