Circular Knitting Elastomeric Yarn Tension Control
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Solution Overview
Problem
Circular knitting machines fail to compensate for the variable package relaxation of elastomeric yarn bobbins, leading to inconsistent tension and quality in the final fabric product, as they typically operate with a fixed speed setting that does not account for the relaxation profile of each bobbin.
Innovation Solution
Implementing a system that adjusts the speed of elastomeric yarn feeding based on the package relaxation profile, using either known or measured data, to maintain constant tension and ensure consistent elastomeric yarn content in the fabric, which can be achieved through computer-controlled motors or expandable pulleys.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If circular knitting machines operate with a fixed speed setting, then the machine structure is simple and easy to operate, but the fabric quality becomes inconsistent due to package relaxation variations
Solution Approach 1:
The patent applies dynamics by transforming the fixed speed control system into a dynamic speed control system that automatically adjusts the unwinding speed based on the package relaxation profile. The control system varies the speed during the unwinding process to compensate for tension changes, thereby maintaining consistent fabric quality without requiring complex manual intervention.
Solution Approach 2:
The patent implements feedback control by using measured or known package relaxation profiles to continuously adjust the unwinding speed. The system monitors the relaxation characteristics and feeds this information back to the speed control mechanism, enabling automatic compensation for tension variations and ensuring consistent fabric quality throughout the knitting process.
2Loss of substance
If the unwinding speed is kept constant, then the machine operation is simple, but elastomeric yarn is wasted due to tension variations
Solution Approach 1:
The patent applies preliminary action by pre-determining or pre-measuring the package relaxation profile before the knitting process begins. This advance knowledge of the relaxation characteristics allows the control system to pre-program the speed adjustments needed to compensate for upcoming tension variations, thereby preventing yarn wastage while maintaining optimal knitting speed throughout the process.
3Force
If package relaxation is not compensated, then the processing is simple and fast, but the tension in the yarn becomes inconsistent
Solution Approach 1:
The patent replaces complex mechanical tension control mechanisms with a more elegant solution: substituting mechanical tension regulation with electronic speed control. By controlling the unwinding speed based on the package relaxation profile, the system achieves consistent yarn tension without requiring complex mechanical tensioning devices, thereby maintaining simplicity while improving tension consistency.
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 results in more consistent fabric quality parameters, reduced wastage of expensive elastomeric yarn, and improved yield by maintaining constant elastomeric yarn content and tension during the knitting process.
Implementation Method 1
Elastomeric yarn typically comprises a continuous filament that has a break elongation in excess of 100% and which, when stretched and released, retracts quickly and forcibly to substantially its original length
Implementation Method 2
a creel controller that controls the unwinding speed of the elastomeric yarn packages based upon a package relaxation profile for the elastomeric yarn packages
Data Source
Figure 1
Figure 2~5
AI summary
When elastomeric yarns (36) are unwound and fed to the needles (18) of a circular knitting apparatus, a yarn package (24) relaxation profile is set, or determined, with corresponding adjustments made to the unwinding speed (V) based on such package relaxation profile. Variably compensating for a varying package relaxation while knitting results in more uniform properties in a circular knit fabric and improved elastomeric yarn yield.