Pneumatic Thread Storage Emptying Control

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Solution Overview

Problem

Existing methods for emptying a pneumatic thread storage device on textile machines producing cross-wound bobbins face issues with slippage and inaccurate thread length detection due to mass inertia and reaction times of sensor devices, leading to unreproducible emptying and inaccuracies in thread length calculation.

Innovation Solution

The method involves accelerating the winding shaft and yarn traversing device to a constant base speed below 30% of operating speed, followed by a gradual increase in speed, allowing for precise thread length calculation without sensors by varying the traversing width and using a high-resolution sensor system or reduced thread laying width, and adjusting the thread take-off speed with a correction factor to control the emptying process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the winding shaft is accelerated during the start-up phase to empty the thread store, then the thread store can be emptied, but slippage occurs due to mass inertia of partially wound bobbins making the process unreproducible

Engineering Contradiction:

Improvethread store emptying efficiencyVSAvoidreproducibility of emptying process

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

A defined length of thread is unwound from the take-up spool and temporarily stored in the thread store device before piecing occurs. This preliminary action prepares the system for controlled emptying by pre-positioning the thread in the store, allowing subsequent acceleration phases to proceed with predictable behavior rather than dealing with variable initial conditions.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The winding shaft is started ahead of the yarn take-off device and constantly accelerated, while the thread draw-off device is started at a later point and accelerated to match. The peripheral speeds are equalized at a specific point in time, creating a dynamic coordination system that adapts to the mass inertia of different bobbin states, ensuring reproducible emptying despite varying load conditions.

Inventive Principle:

Principle #15Dynamics

2Reliability

If sensor devices are used to detect thread store filling level, then reproducibility can be achieved, but reaction time delays cause inaccuracies in thread length calculation

Engineering Contradiction:

Improvereproducibility of emptying controlVSAvoidthread length detection accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent replaces sensor-based detection systems with a mathematical calculation approach. Thread length is determined by integrating the difference between winding speed and yarn drawing speed over time, rather than using physical sensors that suffer from reaction time delays. This substitution of mechanical/optical detection with computational methods eliminates the measurement lag inherent in sensor systems.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

Speed sensors on the winding shaft and yarn take-off device serve as intermediaries to measure rotational speeds, which then feed into a control device that calculates thread length mathematically. This intermediary measurement approach allows indirect but accurate determination of thread consumption without requiring direct sensors in the thread path, avoiding the reaction time problems of direct detection.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Productivity

If the thread store is emptied with stepwise acceleration, then the thread store can be emptied, but the speed difference between winding and take-off speeds becomes difficult to control exactly

Engineering Contradiction:

Improvethread store emptying capabilityVSAvoidspeed difference control precision

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

Speed sensors continuously monitor the rotational speeds of the winding shaft and yarn take-off device, feeding this data back to a control device. The control device calculates the instantaneous speed difference and uses this feedback to determine thread length consumption in real-time, enabling precise control of the emptying process despite the dynamic acceleration phases.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The emptying process is divided into distinct phases: initial acceleration of the winding shaft, delayed start and acceleration of the thread draw-off device, and a final phase where peripheral speeds are equalized. This periodic structuring of the acceleration process creates predictable intervals for thread consumption, allowing the control system to calculate and manage speed differences more effectively throughout the sequence.

Inventive Principle:

Principle #19Periodic action

Data Source

PatentEP2172409B1Method for emptying a pneumatic thread storage device

Publication Date: 2012.07.25 OERLIKON TEXTILE GMBH & CO KG

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AI summary

The method involves accelerating a winding shaft (23) and a thread traversing device (24) at a time point in a constant base speed, which lies below 30 percentage of operating speed. A thread draw-off device (13) is started and accelerated at another time point, where a thread (9) is removed from a clamping device by the thread draw-off device. The winding shaft and the thread traversing device are accelerated from the latter time point, and the thread draw-off device is accelerated upto to a third time point in a terminal velocity in a stationary spinning operation. An independent claim is also included for a cross wound bobbin of a textile machine.