Open-End Spinning Frame Startup Control via Thread Tension
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Solution Overview
Problem
Existing open-end spinning machines face challenges in safely starting work stations and setting the winding device speed during startup, particularly due to variations in thread tension and bobbin diameter, leading to potential thread breakage or insufficient tension, and current sensor systems are costly and inefficient for machines with many work stations.
Innovation Solution
Measuring thread tension at startup for different bobbin diameters to determine diameter-dependent run-up curves, which are used to set the winding device speed, allowing for automatic consideration of varying parameters and simplifying the process by using a pilot work station with a tension sensor and control means to set and apply these curves across all stations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical or capacitive sensor devices are used to monitor the fill level of pneumatic yarn storage devices, then the startup process can be controlled more precisely, but the cost increases significantly
Solution Approach 1:
The patent replaces expensive optical or capacitive sensor devices with a simple thread tension sensor that measures thread tension directly. This cheaper sensing approach provides sufficient information for controlling the startup process without requiring complex fill level monitoring systems.
Solution Approach 2:
The patent substitutes mechanical/thread-based measurement (thread tension sensing) for optical or capacitive sensing systems. The thread tension sensor provides a direct mechanical measurement of the startup process state, eliminating the need for complex electromagnetic sensing infrastructure.
2Productivity
If the winding speed is increased above thread delivery speed during startup, then the pneumatic thread storage can be emptied properly, but thread breakage occurs if maintained too long
Solution Approach 1:
The patent employs feedback control by continuously monitoring thread tension during the startup process. When thread tension exceeds a predetermined threshold, the system automatically reduces the winding speed back to thread delivery speed, preventing thread breakage while maintaining efficient startup operation.
Solution Approach 2:
The patent implements dynamic speed adjustment of the winding device during startup. The winding speed is not fixed but varies based on real-time thread tension conditions, allowing the system to optimize between emptying efficiency and thread safety by transitioning between different speed states.
3Reliability
If the winding speed is reduced to thread delivery speed too early, then thread breakage is prevented, but the cross-wound bobbin is wound without necessary thread tension
Solution Approach 1:
The system uses thread tension feedback to determine the optimal moment to reduce winding speed. By monitoring tension levels in real-time, the control system ensures that high-speed operation is maintained only as long as thread tension remains within safe limits, thereby achieving both thread safety and winding quality.
Solution Approach 2:
The patent establishes predetermined thread tension thresholds and run-up curves before startup begins. These pre-defined parameters guide the winding speed adjustment process, ensuring that the transition to thread delivery speed occurs at the optimal moment for maintaining both thread integrity and winding quality.
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 method ensures safe and cost-effective startup of work stations by accurately managing thread tension and winding speed, preventing thread breakage and ensuring proper tension, while reducing the need for expensive sensor systems by using existing microprocessor-controlled systems and software.
Implementation Method 1
the thread tension is measured for a new batch at least at one work station (54) for different diameters of the cross-wound bobbin when it is run up
Implementation Method 2
A thread storage nozzle that can be subjected to negative pressure is arranged downstream of the thread draw-off device, which temporarily stores the thread excess
Data Source
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AI summary
The present invention relates to a method for operating an open-end spinning machine (1) and an open-end spinning machine (1) with a plurality of working stations (54), wherein a working station (54) has a spinning device (12) and a winding device (18) for producing a cross-wound bobbin (19) and a yarn storage device (4) temporarily stores the amount of yarn that is produced during the start-up of the working station (54) as a result of different start-up speeds of the spinning device (12) and the winding device (18).According to the invention, for a new batch, the thread tension is first measured at least at one work station (54) for different diameters of the cross-wound bobbin (19) during ramp-up, wherein the thread tension is a measure of the fill level of the thread storage device (4), the ramp-up speed of the bobbin winding device (18) is set depending on the thread tension, a ramp-up curve for the different diameters of the cross-wound bobbin (19) is determined from the set speeds and these diameter-dependent ramp-up curves are then used for the respective batch when ramping up the work stations (54).