Elastic Yarn Winding Helix Angle Variation
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Solution Overview
Problem
The formation of running bands during yarn unwinding leads to fabric defects and yarn breaks, as the raised package shoulders cause dislodging of threadline reversals, resulting in aesthetically undesirable and functionally problematic yarn packages.
Innovation Solution
Implementing a method that varies the helix angle of yarn winding, with a range of +/−3% to +/−50%, to flatten the package surface and reduce the sloped shoulder profile, thereby minimizing running band formation by distributing reversals axially and uniformly driving the package surface during unwinding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the traverse guide slows down, changes direction, and speeds up again during winding, then the yarn is deposited in the reversal at the package edge, but the package shoulder becomes raised and sloped, causing running bands during unwinding
Solution Approach 1:
The invention changes the helix angle parameter during winding by varying the package rotational speed. By increasing the helix angle variation, the yarn is distributed more axially along the package length, which flattens the package profile and reduces the raised shoulders that cause running bands during unwinding
Solution Approach 2:
The invention applies dynamic variation to the helix angle during the winding process. The helix angle is continuously varied within a range of +/−3% to +/−50% of the mean helix angle, creating a dynamic winding pattern that distributes yarn reversals axially and prevents the formation of raised package shoulders
2Productivity
If the package shoulder is raised due to additional yarn deposition, then the yarn can be wound with reversals, but the raised shoulder causes dislodging of reversals during unwinding
Solution Approach 1:
By changing the helix angle parameter dynamically during winding, the invention redistributes the yarn reversals axially along the package rather than concentrating them at the package shoulders. This parameter change maintains winding productivity while improving package stability during unwinding
Solution Approach 2:
The invention applies periodic variation to the helix angle during the winding process. This periodic action creates a pattern of yarn distribution that prevents the accumulation of reversals at the package edges, thereby maintaining both productivity and reliability
3Shape
If the helix angle is varied with high amplitude, then the yarn laydown width varies axially to flatten the package, but the winding process becomes more complex
Solution Approach 1:
The invention achieves package surface flatness by varying the helix angle parameter within a controlled range of +/−3% to +/−50% of the mean helix angle. This parameter change distributes yarn axially and flattens the package profile without requiring complex additional equipment
Solution Approach 2:
The dynamic variation of the helix angle is implemented through modulation of the package rotational speed. This dynamic approach achieves the desired package shape while using existing winding machine capabilities, minimizing the increase in device complexity
Data Source
AI summary
A method is provided for winding an elastic yarn into a cylindrical substantially straight-ended yarn package. The method includes feeding an elastic or elastomeric yarn at a substantially constant speed to a tube core to form the yarn package. The yarn package is rotated such that the yarn package with a substantially constant surface speed. The yarn is wound to form layers of helical coils, while providing a helix angle variation of greater than zero up to +/−80%.