Yarn Quality Measuring Instrument Variable Sampling
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Solution Overview
Problem
Conventional yarn quality measuring instruments fail to accurately detect yarn defects and periodic unevenness in automatic winders due to varying yarn speeds, leading to incorrect defect detection and degraded product quality.
Innovation Solution
A yarn quality measuring instrument with first and second sensors and a signal processing section that adjusts sampling frequency based on yarn speed, using FFT analysis and digital low pass filtering to detect thickness unevenness, including periodic variations, regardless of yarn speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the yarn clearer uses a fixed sampling frequency to detect yarn defects, then the device complexity is reduced, but the measurement precision of defect length deteriorates due to varying yarn speeds
Solution Approach 1:
The patent applies dynamics by making the sampling frequency variable rather than fixed. The sampling frequency is dynamically adjusted according to the yarn speed, ensuring that the sampling rate adapts to changing operational conditions. This resolves the contradiction by allowing the system to maintain measurement precision across varying speeds without requiring an overly complex fixed-frequency system.
Solution Approach 2:
The patent changes the parameter of sampling frequency from a constant value to a variable value that depends on yarn speed. By modifying this key parameter, the system achieves accurate defect length measurement across different operating conditions while avoiding the complexity of a purely fixed-frequency approach that would fail to adapt to speed variations.
2Reliability
If the yarn clearer sets a stricter tolerable length value to prevent missing defects on larger diameter side, then the reliability of defect detection is improved, but the productivity deteriorates due to frequent false cuts on smaller diameter side
Solution Approach 1:
The patent implements feedback by using the measured defect length (which is now accurate due to variable sampling frequency) to make intelligent decisions about whether to cut the yarn. The system receives feedback about actual defect characteristics and compares them against dynamically adjusted criteria, allowing it to distinguish between true defects and normal variations. This prevents both missed defects and false cuts, maintaining reliability while preserving productivity.
Solution Approach 2:
The system dynamically adjusts the evaluation criteria based on actual measured defect lengths rather than using a fixed strict threshold. This dynamic approach allows the system to adapt to different packaging conditions (cone-shaped, cheese-shaped) and yarn speeds, maintaining high detection reliability without causing excessive false positives that would reduce productivity.
3Ease of operation
If the yarn clearer monitors yarn thickness at constant speed, then the ease of operation is improved, but the measurement precision deteriorates due to actual speed variations during winding
Solution Approach 1:
The patent replaces the mechanical assumption of constant yarn speed with an electronic/digital speed measurement and compensation system. Instead of relying on mechanical constant-speed operation, the system uses sensors and signal processing to measure actual yarn speed and adjust sampling accordingly. This substitution maintains operational simplicity while achieving precise thickness measurements despite speed variations.
Solution Approach 2:
The system changes the approach from assuming constant speed to actively measuring and compensating for speed variations. By modifying the operational parameter from fixed-speed monitoring to variable-speed adaptive monitoring, the system maintains ease of operation while dramatically improving measurement precision across different winding conditions.
Data Source
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AI summary
An object of the present invention is to provide a yarn quality measuring instrument and a yarn winding machine which can accurately evaluate the length of a yarn defect and detect periodic unevenness. A winder unit 10 constituting an automatic winder includes a clearer (yarn quality measuring instrument) 15. The clearer 15 detects thickness unevenness in a spun yarn 20 traveling with a speed thereof varied, to detect the thickness unevenness in the yarn. The clearer 15 includes a first yarn unevenness sensor 43 detecting the thickness of the traveling yarn, and a CPU 47. The CPU 47 receives a yarn speed signal obtained from an external rotation sensor 42 to sample signals from the first yarn unevenness sensor 43 at a sampling frequency according to the yarn speed signal (Fig.2).