Ultrasonic Hardened Layer Depth Measurement
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Solution Overview
Problem
Existing non-destructive methods for measuring the depth of hardened surface layers, such as those using ultrasonic waves, are prone to errors due to operator misreadings of echo propagation times, affecting the accuracy of calculated layer depths.
Innovation Solution
A method and apparatus that involve creating calibration curves using pairs of samples with varying carburization depths, where one sample is subjected to a destructive test and the other to a non-destructive ultrasonic test, allowing for the calculation of hardened surface layer depth with reduced error by averaging propagation times of first and second peaks in the waveform.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the time taken for an echo to rise is measured to calculate the rate of change of sound wave speed, then the hardened surface layer depth can be measured non-destructively, but the measurement is prone to operator reading errors which adversely affect the calculation accuracy
Solution Approach 1:
The patent replaces manual operator measurement with automated electronic signal processing. Specifically, it substitutes the mechanical/manual process of measuring echo rise time with an automated system that detects the intersection point of the echo waveform with a reference line using electronic circuits and calculation units, thereby eliminating operator reading errors and improving measurement reliability
Solution Approach 2:
The patent introduces an intermediary reference line that intersects with the echo waveform at a specific point. This reference line serves as a mediator between the raw echo signal and the final depth calculation, providing a clear, unambiguous intersection point that can be automatically detected by electronic systems, thus improving both precision and reliability
2Measurement precision
If the Vickers hardness test is used to measure hardened surface layer depth, then the measurement can be performed, but it is a destructive test that takes time and cannot be applied to pieces intended for actual product use
Solution Approach 1:
The patent replaces the mechanical destructive Vickers hardness test with a non-destructive ultrasonic wave-based measurement system. The system uses acoustic waves to probe the material properties and calculate hardened layer depth without physical contact or damage to the test piece, enabling measurement of actual product components
Solution Approach 2:
The patent changes the measurement parameter from direct physical indentation (Vickers test) to acoustic wave propagation characteristics. By measuring the time taken for ultrasonic waves to traverse the hardened layer and calculating the rate of change of sound wave speed, the system obtains depth information without altering the material structure
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 significantly reduces errors in measuring hardened surface layer depth, improving accuracy and enabling precise evaluation of mechanical qualities like strength and abrasion resistance without damaging the material.
Implementation Method 1
a transmitter probe and a receiver probe which are placed on a surface of interest of a sample to measure propagation time of a first wave of a waveform of a signal outputted by the receiver probe receiving a surface wave transmitted from the transmitter probe to propagate along the surface of the sample
Data Source
AI summary
A method comprises a calibration curve creation step in which a calibration curve is created on the basis of hardened surface layer depth. A destructive test is performed on one of two samples in pairs, and propagation time of a first peak of a first wave of waveform of a signal outputted with the other in pairs in a non-destructive test is determined, the samples in pairs being prepared such that carburization depth varies gradually from pair to pair. A waveform of a signal outputted with a to-be-inspected piece is obtained. The propagation time of a first peak of a first wave of the waveform of the signal output with the to-be-inspected piece is obtained, and the hardened surface layer depth of the to-be-inspected piece is obtained using the calibration curve, on the basis of the propagation time obtained with the to-be-inspected sample.