Elastic Yarn Tension Control in Flatbed Knitting
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Solution Overview
Problem
In flatbed knitting machines, controlling the tension of elastic yarns is challenging due to fluctuations during the knitting process, leading to variations in stitch loop size and hand feeling, which affects the quality of knitted fabrics, especially when using elastic yarns with high retractility properties.
Innovation Solution
An apparatus and method that utilize a yarn sending device and tension meter to detect tension changes during the resting phase of the knitting process, calculate the difference in natural yarn lengths under designated and actual tensions, and adjust the yarn sending length to maintain consistent tension, allowing for accurate correction without lowering knitting efficiency or restricting patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If elastic yarns with high retractility properties are used to achieve large retractility in fabric portions, then the retractility property is improved, but the tension fluctuation increases leading to non-uniform stitch loop sizes
Solution Approach 1:
The patent implements a feedback control system where a tension sensor continuously monitors the elastic yarn tension during knitting, and the yarn sending device adjusts the yarn sending length based on the detected tension to maintain constant tension despite the high retractility of the elastic yarns
Solution Approach 2:
The patent performs preliminary tension adjustment by detecting the yarn tension during the resting phase before the knitting action begins, and pre-adjusting the yarn sending length to compensate for expected tension changes during the knitting cycle
2Ease of operation
If yarn tension is controlled during the resting phase of knitting needles, then the tension control is simplified, but the tension fluctuation during knitting action cannot be eliminated
Solution Approach 1:
The system performs preliminary tension measurement and adjustment during the resting phase when knitting needles are not active, establishing an initial tension baseline before knitting begins
3Measurement precision
If the carriage is stopped to correct yarn sending length accurately, then the tension accuracy is improved, but the knitting efficiency is lowered
Solution Approach 1:
The system performs yarn sending length correction during the resting phase before knitting begins, so that accurate tension measurement and correction can be completed without interrupting the knitting production flow
Solution Approach 2:
The tension control and correction operations are integrated into the existing knitting cycle's resting phase, allowing the system to maintain continuous productive operation without additional stopping or idle time
4Ease of operation
If elastic yarn is fed at a fixed yarn sending length, then the knitting process is simplified, but the tension changes from the designated value due to yarn slip and resistance
Solution Approach 1:
The patent implements a feedback mechanism where the tension sensor detects actual yarn tension during the resting phase, and the system automatically adjusts the yarn sending length based on the detected tension to maintain the designated tension value
Solution Approach 2:
The system uses its own tension detection capability to automatically self-correct the yarn sending length without external intervention, compensating for yarn slip and resistance effects
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 solution enables the use of elastic yarns while maintaining consistent tension, ensuring uniform stitch loop sizes and hand feeling in knitted fabrics, without reducing knitting efficiency or imposing pattern restrictions, by accurately correcting yarn sending length based on real-time tension measurements.
Implementation Method 1
a tension meter that confronts a yarn route pathway established between the yarn sending device and the knitting needles, and detects tension of elastic yarns in a resting phase
Implementation Method 2
Elastic yarns are also called rubber yarns, etc., and are made from polyurethane fibers, polyether/ester based fibers, and other fibers with large elasticity and retractility properties
Implementation Method 3
The elastic yarns which are used as inserted yarns are used for knitting in the elongated state with comparatively large tension applied and in the fabric after knitting, tension is released and the elastic yarns shrink
Data Source
Figure 1
Figure 2(a)~2(b)
Figure 3
AI summary
To provide an apparatus and a method for knitting fabric using elastic yarns, in which the elastic yarns are able to be used while correcting the difference between the set tension and the actual tension without being subject to a lowered knitting efficiency or restrictions to knitting patterns. In a knitting machine 1, a tension meter 7 detects the actual tension T2 of a rubber yarn 5 when a carriage 3 reverses the running direction outside the knitting width of a fabric 9. The yarn sending length F at which the rubber yarn 5 is sent out from a yarn sending device 8 to a yarn route pathway for each knitting course is able to be obtained in advance as the length of the rubber yarn 5 consumed under the designated tension T1 for each knitting course. The yarn sending length F is corrected in such a manner that the difference between natural lengths L1, L2 of the rubber yarn 5, existing in the yarn route pathway under the set tension T1 and the actual tension T2, decreases.