Metal Surface Coverage Rate Determination via CIELAB Calibration

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Solution Overview

Problem

Current methods for determining the degree of coverage after surface treatments like shot blasting are subjective, time-consuming, and rely on visual inspection, leading to inconsistent results due to operator variability and inability to accurately assess coverages above 98%.

Innovation Solution

A method using the CIELAB color space to determine coverage by establishing a calibration function based on color parameters such as lightness (L*), chromatic components (a* and b*), and colorimetry difference (ΔE), allowing for precise, non-invasive measurement without visual inspection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If visual inspection with magnifying glass or binocular microscope is used to assess coverage, then the method is simple and requires no special equipment, but the measurement precision is insufficient (cannot distinguish coverages greater than 98%) and reliability is low due to operator subjectivity

Engineering Contradiction:
Improvecoverage measurement precisionVSAvoidmeasurement system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical/optical visual inspection system (magnifying glass, binocular microscope) with a colorimetric measurement system using a colorimeter or spectrophotometer. This substitution enables precise quantitative measurement of coverage by measuring color parameters (L*, a*, b*) that objectively reflect the degree of shot peening, eliminating the inability to distinguish coverages above 98% and removing operator subjectivity.

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

Solution Approach 2:

The patent transforms the coverage assessment from a visual judgment based on surface appearance to a quantitative measurement based on color parameters. By establishing a calibration function that correlates color parameters (L*, a*, b*) with coverage rates, the system can precisely determine coverage including values greater than 100%, thereby improving measurement precision beyond the limitations of visual inspection.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If visual inspection by operator is used to assess coverage, then no additional equipment is needed, but the reliability is low due to operator variability and subjectivity

Engineering Contradiction:
Improvecoverage assessment reliabilityVSAvoidinspection time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent replaces the human operator's visual assessment system with an automated colorimetric measurement system. This substitution eliminates operator variability and subjectivity, providing consistent and reliable coverage measurements. The automated system objectively measures color parameters and calculates coverage based on calibration functions, ensuring high reliability across different operators and inspections.

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

Solution Approach 2:

The patent implements a self-calibrating measurement system where the colorimeter automatically determines coverage by comparing measured color parameters with pre-established calibration functions. The system performs self-assessment without requiring operator intervention for judgment, thereby improving reliability while reducing inspection time through automated processing.

Inventive Principle:
Principle #25Self-service

3Adaptability or versatility

If calibration is performed before each measurement series using visual assessment, then the measurement can be adapted to different parts, but the process remains subjective and time-consuming

Engineering Contradiction:
Improvemeasurement adaptability to different partsVSAvoidcalibration time
Core Design Contradiction:
Adaptability or versatilityVSLoss of time

Solution Approach 1:

The patent replaces subjective visual calibration with objective colorimetric calibration. The calibration process uses a colorimeter to measure color parameters of reference samples with known coverage rates, establishing calibration functions that correlate color parameters with coverage. This objective approach eliminates the time-consuming and subjective visual assessment step while maintaining adaptability to different parts through material-specific calibration.

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

Solution Approach 2:

The patent transforms the calibration process from visual parameter assessment to quantitative color parameter measurement. By establishing mathematical calibration functions that relate color parameters (L*, a*, b*) to coverage rates, the system enables rapid and objective calibration for different materials and surface conditions, reducing calibration time while maintaining versatility.

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

Enables accurate and consistent determination of coverage rates, including values greater than 100%, reducing operator dependency and improving measurement efficiency.

Implementation Method 1

A method using the CIELAB color space to determine coverage by establishing a calibration function based on color parameters such as lightness (L*), chromatic components (a* and b*), and colorimetry difference (ΔE)

Methodology Applied
Scientific EffectColorimetry:

Data Source

PatentEP3607302B1Method of determining the coverage rate of a metal object the surface roughness of which has been altered by a treatment
Publication Date: 2023.03.15 SAFRAN SA
  • EP3607302B1 patent drawingFigure 1~3
  • EP3607302B1 patent drawingFigure 4~5
  • EP3607302B1 patent drawingFigure 6~8

AI summary

A method for determining the degree of coverage of a metal part having undergone a treatment modifying the surface roughness of said part, characterised in that it comprises the following steps: - a step of determining a calibration function (C) of a parameter (L*) of the CIELAB colour space as a function of the degree of coverage, in such a way as to be able to link a given value of said parameter (L*) with the corresponding value of the degree of coverage, - a step of measuring the value of said parameter (L*) of the part, and - a step of determining the degree of coverage of said part by linking, using the calibrating function, the corresponding value of the degree of coverage of the part with the value of said parameter measured in this way (L*).