Yarn Tension Control Device with Dynamic Friction Rolls
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Solution Overview
Problem
The textile industry faces challenges in maintaining uniform yarn tension due to stress variations caused by the shrinking size of the yarn supply package as yarn is unwound and pulled downstream to a textile machine, leading to inconsistent delivery tension.
Innovation Solution
A yarn tension control device with opposing friction rolls and a pivoted rocker block that adjusts frictional resistance based on unwinding tension, applying greater resistance at low tension and lesser resistance at high tension to maintain a constant delivery tension, utilizing a compression spring and rotatable cam wheel for adjustable biasing force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the yarn supply package shrinks as yarn is unwound, then the unwinding tension increases, but the delivery tension becomes inconsistent and non-uniform
Solution Approach 1:
The patent employs a dynamic tension control system with adjustable friction rolls that can modify frictional resistance in real-time based on the unwinding tension conditions. The system transitions from static friction to dynamic adjustment, allowing the friction rolls to adapt their engagement level according to the changing tension state of the yarn during unwinding.
Solution Approach 2:
The invention changes the frictional resistance parameter dynamically by adjusting the normal force between the friction rolls and the yarn. Through the pivoted rocker block mechanism, the system varies the frictional resistance parameter in response to unwinding tension changes, thereby maintaining consistent delivery tension despite package shrinkage.
2Force
If greater frictional resistance is applied to low tension yarn, then delivery tension is maintained, but yarn stress variations are not compensated
Solution Approach 1:
The patent implements a feedback control mechanism where the tension control device continuously monitors the actual delivery tension and adjusts the frictional resistance accordingly. The pivoted rocker block responds to tension variations and automatically modifies the friction roll engagement, creating a closed-loop system that compensates for stress variations while maintaining target delivery tension.
Solution Approach 2:
The system applies preliminary anti-action by anticipating tension variations through the pivoted rocker block mechanism. When unwinding tension changes occur, the rocker block pivots to pre-adjust the frictional resistance before the full tension variation affects delivery, thereby compensating for stress variations proactively rather than reactively.
3Device complexity
If friction rolls are fixed, then device complexity is low, but tension control adaptability is insufficient
Solution Approach 1:
The patent transforms the fixed friction roll configuration into a dynamic system where the friction rolls can adjust their position and engagement level. The pivoted rocker block enables the friction rolls to move and adapt their frictional resistance based on real-time tension conditions, providing tension control adaptability while maintaining relatively simple device architecture.
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
The device ensures a uniform and constant yarn delivery tension by dynamically adjusting frictional resistance, compensating for stress variations and maintaining consistent yarn delivery to textile machines.
Implementation Method 1
Means are provided for resiliently urging the first and second yarn engaging surfaces together
Implementation Method 2
First and second opposing yarn engaging surfaces... adapted to frictionally engage opposite sides of the running yarn... The opposing friction rolls cooperate to form a plurality of sequentially spaced nip points adapted to adjust yarn delivery tension
Data Source
AI summary
A yarn tension control device controls tension in a running yarn. The tension control device includes a housing having a yarn guiding inlet for receiving running yarn at an unwinding tension from a yarn supply source, and a yarn guiding outlet for guiding running yarn exiting the housing at a delivery tension. First and second opposing yarn engaging surfaces are disposed between the inlet and the outlet, and are adapted to frictionally engage opposite sides of the running yarn along a path of yarn travel through the housing. The first and second yarn engaging surfaces define a respective plurality of sequentially spaced friction rolls. A biasing assembly resiliently urges the first and second yarn engaging surfaces together. The opposing friction rolls cooperate to form a number of sequentially spaced nip points adapted to adjust yarn delivery tension in response to stress variations in running yarn entering the housing.