Engraving Device for Flat Coating Stress Corrosion Testing

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Solution Overview

Problem

Current methods for measuring stress corrosion cracking on coated surfaces are inefficient and require complex setups, especially for flat test specimens, and do not effectively assess layer adhesion over large areas with low geometric requirements.

Innovation Solution

A method using a rotatable engraving device with controlled contact pressure and speed to introduce mechanical load on a flat coated test specimen, combined with light-optical evaluation and potential exposure to corrosive media to accelerate stress corrosion cracking, allowing for efficient analysis of layer adhesion and delamination.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional methods (Rockwell indentation, scratch test, Taber-Abraser) are used to measure coating adhesion, then coating adhesion can be assessed, but the methods are complex and do not provide efficient large-area testing with minimal geometric requirements

Engineering Contradiction:
Improvetesting efficiencyVSAvoidtest setup complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical testing systems (Rockwell indentation, scratch test, Taber-Abraser) with a simplified engraving device that uses a rotating engraving head to create grooves on the coating surface. This substitution eliminates the need for complex mechanical stress application and visual evaluation systems, achieving faster, more efficient testing with minimal geometric requirements.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent extracts the essential function of adhesion testing from complex multi-step procedures and isolates it to a single groove-creation and measurement operation. By removing unnecessary test components and focusing only on the critical groove formation and optical measurement, the method achieves streamlined efficiency while maintaining testing validity.

Inventive Principle:
Principle #2Taking out (Extraction)

2Measurement precision

If mechanical stress is applied to induce delamination for adhesion measurement, then coating quality can be evaluated, but the process is time-consuming and requires subjective visual evaluation

Engineering Contradiction:
Improveadhesion measurement accuracyVSAvoidtesting time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent replaces subjective visual evaluation methods with automated optical measurement systems. After the engraving head creates grooves that induce delamination, the system uses optical methods to automatically measure and evaluate the delamination extent, eliminating time-consuming subjective assessment while maintaining measurement precision.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The test system performs self-evaluation by automatically measuring the groove characteristics and delamination patterns without requiring external visual inspection. The optical measurement system inherently provides the evaluation data, making the system self-sufficient and eliminating the time loss associated with manual visual assessment.

Inventive Principle:
Principle #25Self-service

3Reliability

If the engraving head penetrates deeply into the coating system to create engravings, then stress corrosion cracking can be induced, but excessive plastic deformation may occur

Engineering Contradiction:
Improvestress corrosion cracking inductionVSAvoidcoating deformation control
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent employs precise control of engraving parameters including contact force, rotational speed, and traverse speed to optimize the balance between inducing stress corrosion cracking and avoiding excessive plastic deformation. By dynamically adjusting these parameters, the system achieves reliable crack induction while maintaining coating integrity and measurement precision.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses a rotating engraving head with controlled contact force that dynamically adapts to the coating properties. The rotational motion combined with controlled penetration creates stress concentration at the coating-substrate interface without causing uncontrolled plastic deformation, achieving reliable testing through dynamic parameter control.

Inventive Principle:
Principle #15Dynamics

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

Enables simple and efficient testing of stress corrosion cracking on flat specimens with minimal geometric requirements, providing comprehensive analysis of layer adhesion and delamination across large areas, including high and low temperature conditions, and accelerates stress corrosion cracking for enhanced evaluation.

Implementation Method 1

at least one engraving is produced on the test specimen surface by plastic deformation and/or brittle fracture of the coating system

Methodology Applied
Scientific EffectPlastic deformation: Plasticity

Implementation Method 2

at least one engraving is produced on the test specimen surface by plastic deformation and/or brittle fracture of the coating system

Methodology Applied
Scientific EffectBrittle fracture: Fracture Mechanics

Implementation Method 3

The engraving, at least one of which is applied to the surface of the test specimen, is then measured using a light-optical method to evaluate the adhesion of the coating system to the base material

Methodology Applied
Scientific EffectLight-optical detection: Light

Data Source

PatentEP3714255B1Method for creating and measuring stress corrosion cracking on a flat coating test specimen and use of an engraving device for carrying out the method
Publication Date: 2022.05.11 ROBERT BOSCH GMBH
  • EP3714255B1 patent drawingFigure 1~2

AI summary

The invention relates to a method for carrying out a test and measuring method on a flat test specimen (1), wherein a mechanical load is introduced into a test specimen surface (2) by means of a rotating engraving head (3) of an engraving device (4), wherein the engraving head (3) penetrates with a defined contact pressure at least into a layer system (5) applied to the test specimen (1), wherein the rotating engraving head (3) is moved along the test specimen surface (2) and relative to the test specimen (1) in order to create at least one engraving (6) on the test specimen surface (2) by plastic deformations and/or brittle chipping of the layer system (5), and wherein the at least one engraving (6) introduced into the test specimen surface (2) is measured using a photo-optical method in order to evaluate layer adhesion of the layer system (5) to the main body (11). The invention also relates to an engraving device (4) for carrying out such a method.