Optical Inspection Laser Heating for Joint State Stability

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Solution Overview

Problem

Existing optical non-destructive inspection methods face challenges in achieving stable joint state determination between joined members due to fluctuations in surface roughness and signal-to-noise ratio, particularly in regions with unstable contact states, which affects the accuracy of joint portion area measurements.

Innovation Solution

The method involves a preliminary heating step using a thermal distortion generation intensity laser to convert unstable contact regions into stable non-contact states, followed by a heating laser emission step to acquire measurement point information, allowing for more stable joint state determination by suppressing fluctuations and improving surface roughness and emissivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If high-power laser is irradiated to form oxide film at measurement point, then surface roughness is stabilized and emissivity is improved, but the unstable contact region (region B) cannot be eliminated and joint state fluctuations persist

Engineering Contradiction:
Improvejoint state measurement precisionVSAvoidjoint state stability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent applies preliminary heating action by irradiating the measurement point with heating laser before performing the actual joint state measurement. This preliminary heating stabilizes the temperature and eliminates fluctuations caused by unstable contact regions, thereby improving measurement reliability without sacrificing precision

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent changes the temperature parameter by applying heating laser to raise the measurement point temperature to a stable state (e.g., 100°C or higher) before measurement. This parameter change transforms the unstable contact region into a stable state, eliminating fluctuations in joint state determination

Inventive Principle:
Principle #35Parameter changes

2Productivity

If measurement is performed without preliminary heating, then measurement process is simple and quick, but joint portion area fluctuates significantly due to unstable contact state transitions

Engineering Contradiction:
Improvemeasurement efficiencyVSAvoidjoint portion area measurement precision
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The patent introduces a preliminary heating step before measurement that quickly stabilizes the measurement point temperature. This preliminary action eliminates the need for repeated measurements due to fluctuations, thereby maintaining high measurement efficiency while improving precision

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent rushes through the unstable contact state by applying sufficient heating to quickly transition region B into a stable state. This allows the measurement to proceed without being affected by transient fluctuations, maintaining both speed and accuracy

Inventive Principle:
Principle #21Skipping (Rushing through)

3Measurement precision

If heating laser is applied to stabilize temperature, then surface roughness fluctuation is suppressed and emissivity is improved, but additional heating step increases measurement time

Engineering Contradiction:
Improvetemperature measurement precisionVSAvoidmeasurement time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent performs preliminary heating to stabilize temperature before measurement, which eliminates the need for repeated measurements due to fluctuations. Although this adds an initial heating step, it reduces total measurement time by preventing re-measurements

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent maintains continuous heating during the measurement process to ensure the measurement point remains in a stable thermal state. This continuous useful action prevents temperature fluctuations that would otherwise require interrupting the measurement

Inventive Principle:
Principle #20Continuity of useful action

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 approach enhances the precision and stability of joint state assessment by converting unstable contact regions into stable non-contact states, reducing fluctuations and improving measurement accuracy, enabling more reliable joint state determination across various joint configurations.

Implementation Method 1

a measurement point set on a surface of a first member (91) is irradiated with heating laser

Methodology Applied
Scientific EffectLaser heating: Laser

Implementation Method 2

The oxide film stably has a significantly high absorptivity (emissivity)... the temperature rise characteristics during irradiation with the heating laser

Methodology Applied
Scientific EffectLight absorption and conversion to thermal energy: Absorption (EM radiation)

Implementation Method 3

measure the temperature rise characteristics... an intensity of infrared light radiated from the measurement point

Methodology Applied
Scientific EffectThermal radiation: Thermal Radiation

Data Source

PatentEP3431972B1Optical non-destructive inspection method and optical non-destructive inspection apparatus
Publication Date: 2022.06.15 JTEKT CORP
  • EP3431972B1 patent drawingFigure 1
  • EP3431972B1 patent drawingFigure 2
  • EP3431972B1 patent drawingFigure 3

AI summary

An optical non-destructive inspection method includes: a heating laser emission step; an information acquisition step of acquiring measurement point information and heating laser information; a joint state determination step of determining the joint state on the basis of the measurement point information and the heating laser information; and a preliminary heating step, which is performed before the heating laser emission step, of causing thermal distortion in a first member by irradiating a measurement point, or a preliminary heating range that includes the measurement point, or a preliminary heating point set in the preliminary heating range, with preliminary heating laser adjusted to a thermal distortion generation intensity, which is a constant output intensity, and an irradiation time such that the thermal distortion is caused without destroying the first member.