Yarn Tension Control Block for Negative Yarn-Feeder

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Solution Overview

Problem

Negative yarn-feeders struggle to maintain optimal yarn tension during low-operative conditions, such as starting the weaving process or threading, where tension can drop to zero, leading to excessive braking and potential yarn breakage due to high tension peaks when operation resumes.

Innovation Solution

A control system that disables the tension control block during low yarn consumption speeds and freezes the braking level until the speed exceeds a threshold, ensuring stable yarn tension by enabling the tension control only when the yarn consumption speed surpasses a predetermined value, preventing excessive braking.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the tension control block is enabled during low yarn consumption speeds, then the tension can be controlled, but the braking level increases excessively causing yarn tension peaks and potential yarn breakage

Engineering Contradiction:

Improveyarn tension controlVSAvoidyarn integrity

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The control system dynamically adjusts the operational state of the tension control block based on yarn consumption speed. The block is disabled when speed is below a threshold and enabled when speed exceeds the threshold, creating a dynamic control strategy that adapts to varying operational conditions to prevent excessive braking during low-speed operations

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the operational parameter (enabling/disabling state) of the tension control block based on the yarn consumption speed parameter. By monitoring speed and using it as a threshold condition, the system modifies the control block's state to appropriate operational levels, preventing excessive braking action during low-speed conditions

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If the braking action is increased to compensate for low tension during starting or threading, then the desired tension value can be reached, but the yarn tension peaks causing textile defects

Engineering Contradiction:

Improvetension control precisionVSAvoidtextile defects

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The control system takes preliminary action by disabling the tension control block before problematic conditions occur. By detecting low yarn consumption speed as a precursor to potential tension control issues, the system proactively disables the block to prevent excessive braking and subsequent yarn tension peaks that would cause textile defects

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS8086342B2Method for controlling the tension of the yarn unwinding from a negative yarn-feeder for textile machines, and apparatus for carrying out such method

Publication Date: 2011.12.27 L G L ELECTRONICS SPA

AI summary

The tension is modulated by a weft-braking device controlled by a tension control block programmed for comparing the measured tension with a reference tension, and for transmitting a braking level signal to the weft-braking device, which braking level signal is adapted to minimize the difference between the measured tension and the reference tension. The yarn consumption speed is calculated, then the yarn consumption speed is compared with a predetermined threshold speed, and if the calculated consumption speed overcomes the predetermined threshold value, the tension control block is enabled, while, if the calculated consumption speed is lower than the threshold value, the tension control block is disabled and the last signal generated by the latter is maintained as braking signal, until the yarn consumption speed overcomes again the threshold value.