Adaptive Periodic Defect Detection for Variable Roll Diameters
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for detecting periodic defects in belt-like or columnar bodies, such as steel sheets, struggle to accurately identify defects when the defect development period varies or when rolls have different diameters, leading to issues with sensitivity and accuracy, especially in detecting minor defects.
Innovation Solution
A periodic defect detection apparatus that uses a sensor to obtain signals from an area longer than the expected defect period, with a small area selection mechanism to determine positions of small areas with equal distance intervals, and an evaluation index calculation to assess similarity between signal patterns, allowing for accurate period judgment even when the defect development period fluctuates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If synchronous addition is used at an expected period to detect periodic defects, then periodic defect signals are emphasized from noise, but the method cannot be applied when the period varies due to roll wear or diameter changes
Solution Approach 1:
The patent applies dynamics by making the reference period adaptive rather than fixed. The system dynamically adjusts the reference period based on actual defect interval measurements from the production line, allowing it to accommodate roll wear and diameter changes while maintaining accurate periodic defect detection
Solution Approach 2:
The system changes the parameter of the reference period from a static expected value to a dynamic value that is updated based on actual defect measurements. This parameter adaptation enables the system to handle varying defect periods caused by roll wear without sacrificing detection accuracy
2Measurement precision
If defect detection sensitivity is increased to detect minor defects, then more defects are detected, but false positives increase due to noise and sudden defects
Solution Approach 1:
The system uses feedback by measuring actual defect intervals and using them to update the reference period. This feedback mechanism allows the system to adapt to real conditions and distinguish true periodic defects from random noise, reducing false positives while maintaining high sensitivity
Solution Approach 2:
The system performs preliminary measurement of defect intervals to establish an accurate reference period before conducting the main detection. This preliminary action enables the system to be tuned to the actual production conditions, improving both sensitivity and reliability
3Productivity
If the detection area is reduced to focus on specific defect patterns, then detection speed increases, but the ability to detect defects with varying periods decreases
Solution Approach 1:
The system achieves both speed and adaptability by dynamically adjusting the reference period based on actual measurements. The detection area remains focused for speed, while the dynamic reference period provides the versatility to handle varying defect periods
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An apparatus for detecting periodic defect, has: a sensor 4; a small area selection means (72, 74) for separating a plurality of small areas whose area length is shorter than that of the area so that all distance intervals adjacent to one another are equal in a periodic defect arrangement direction to determine positions of the plurality of small areas, and selecting signals corresponding to the positions of the plurality of small areas from outputs from the sensor; an evaluation index calculation means 76 for calculating a similarity evaluation index between signal patterns among a plurality of signals selected by the small area selection means; a set value changing means (73, 75) for changing the positions of the small areas and the distance interval, and repeating computational processings of the small area selection means and the evaluation index calculation means; and a period judgment means 77 for judging the distance interval as a period when the evaluation index is higher than a value set beforehand. A method for detecting periodic defect has a signal inputting step, a small area selecting step, an evaluation index calculation step, a set value changing step, and a periodicity judging step.