Optical Scanning for Warp Thread Speed Monitoring
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Solution Overview
Problem
Existing warp knitting machines face difficulties in reliably detecting errors such as thread breaks and stitching errors, particularly in the edge area of the knitted fabric, due to irregular structures and shrinkage, which complicates the detection of defects like thread breaks and interlaced errors.
Innovation Solution
An optical scanning device is positioned to capture moving images of warp threads in the thread feed area, allowing the data processing unit to evaluate thread running speeds and generate evaluation signals for detecting defects, eliminating the need for drop bars and light barriers, and enabling early detection of errors like thread breaks and tension issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical scanning is performed on the knitted fabric in the knitting area, then product quality monitoring is achieved, but detection reliability deteriorates due to irregular edge structure and shrinkage
Solution Approach 1:
The optical scanning device monitors warp threads in the thread feed area before they enter the knitting area. By performing quality control preliminarily, the system detects thread breaks and defects before they affect the knitted fabric structure, avoiding the unreliable edge area detection problem
Solution Approach 2:
The patent uses the warp threads themselves as an intermediary monitoring object. Instead of directly scanning the problematic knitted fabric, the system monitors the threads that will form the fabric, using their running speed and position as indicators of potential defects
2Reliability
If drop bars are used to detect thread breaks in the edge area, then detection reliability improves, but device complexity increases significantly
Solution Approach 1:
The optical scanning device performs multiple functions: it monitors all warp threads simultaneously, detects thread breaks, measures running speed, and identifies positioning errors. This single device replaces multiple specialized components including drop bars for each thread
Solution Approach 2:
The patent replaces the mechanical drop bar system with an optical scanning system. The optical device uses light and image processing to detect thread breaks and defects, eliminating the need for physical contact sensors for each individual thread
3Reliability
If a light barrier is used to detect thread breaks, then some defects can be detected, but detection completeness deteriorates since not all broken threads pass through the monitoring area
Solution Approach 1:
The optical scanning device captures two-dimensional image data of the thread feed area, providing comprehensive coverage of all warp threads across the width of the fabric. This multi-dimensional monitoring ensures no broken thread escapes detection, unlike linear light barriers
4Extent of automation
If image processing is used to monitor the knitted fabric, then automated quality control is achieved, but detection accuracy deteriorates in the edge area due to frayed structure and curling
Solution Approach 1:
The system performs automated monitoring of warp threads before they enter the knitting area where edge effects occur. By monitoring earlier in the process, the system avoids the frayed and curled edge structures that compromise image processing accuracy
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 allows for the reliable detection of thread breaks, stitching errors, and other quality deficits, enabling the warp knitting machine to stop the process quickly when errors occur, improving overall product quality by identifying faults earlier than traditional methods.
Implementation Method 1
the optical scanning device is aimed at the warp threads (4) in the thread feed area (3)
Data Source
Figure 1~2
Figure 3
AI summary
The invention relates to a warp knitting machine (1) with a knitting area (5) in which the warp knitting machine (1) produces a knitted fabric (2) during a knitting process, with a yarn feed area (3) in which warp threads (4) pass during operation of the warp knitting machine (1) before being subjected to the knitting process in the knitting area (5), and with a system for monitoring the quality of the knitted fabric (2), wherein the system for monitoring the quality of the knitted fabric (2) comprises an optical scanning device (7) and a data processing unit, and wherein the data processing unit is configured to generate an evaluation signal relating to the quality of the knitted fabric (2).According to the invention, the optical scanning device (7) is arranged in such a way that it can detect a moving image of at least one warp thread (4) in the thread feed area (3), wherein the data processing unit is configured to determine a thread travel speed of the at least one warp thread (4) from the moving image, to evaluate the thread travel speed in an evaluation step and to generate the evaluation signal depending on an evaluation result of the evaluation step.