Weft Thread Insertion Control via Non-Contact Measurement
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Solution Overview
Problem
Conventional air-jet weaving machines face challenges in accurately controlling weft thread insertion due to imprecise measurement methods, which lead to increased compressed air consumption and potential damage to warp threads, resulting in suboptimal fabric quality.
Innovation Solution
The implementation of non-contact measuring sensors to continuously or repeatedly measure the speed and distance of the weft thread after the acceleration nozzle, allowing for precise control of the weft insertion process by adjusting nozzle activation and pressure, thereby reducing the risk of warp thread damage and improving measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple weft thread monitors are arranged in the shed to detect weft thread arrival, then measurement precision is improved, but the warp threads may be damaged and fabric quality is influenced
Solution Approach 1:
The patent extracts the measurement function from the shed area and relocates it to the thread store area. Instead of placing monitors in the shed where they could damage warp threads, the system uses the existing winding counter on the thread store to measure weft thread position and speed, eliminating the harmful interaction between monitors and warp threads while maintaining measurement capability
Solution Approach 2:
The patent introduces an intermediary measurement approach by using the winding counter to indirectly determine weft thread position through the thread store rotation. This intermediary method allows measurement without direct contact in the shed, avoiding damage to warp threads while still providing the needed position and speed data for control
2Productivity
If compressed air is supplied to auxiliary nozzles for weft thread transport, then weft thread insertion is enabled, but compressed air consumption increases massively
Solution Approach 1:
The patent applies dynamics by making the auxiliary nozzle operation adaptive rather than fixed. The control system adjusts the timing and duration of auxiliary nozzle activation based on real-time weft thread position and speed measurements from the winding counter, ensuring compressed air is supplied only when and where needed, thereby reducing overall consumption while maintaining insertion capability
Solution Approach 2:
The patent implements feedback control where the winding counter measurements of weft thread position and speed are continuously fed back to the control system. This feedback allows dynamic adjustment of auxiliary nozzle operation, optimizing compressed air usage by activating nozzles only when the weft thread requires assistance, thus reducing energy loss while maintaining productivity
3Measurement precision
If the weft thread is drawn off irregularly from the drum store, then measurement precision is reduced, but the control system becomes more complex
Solution Approach 1:
The patent replaces complex mechanical measurement and control systems with a simpler optical/electronic measurement approach. Instead of using multiple mechanical monitors and complex control mechanisms, the system uses the winding counter to measure thread store rotation and calculates weft thread position, simplifying the overall system while maintaining measurement precision despite irregular thread withdrawal
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 approach enables more precise control of weft thread insertion, reduces the influence of thread tension and elongation, and allows for quicker detection of faults, leading to improved fabric quality and reduced compressed air consumption.
Implementation Method 1
the weft thread drawn off from a thread store is accelerated by acceleration nozzles
Implementation Method 2
it is entered into a shed, in which it is transported further by so-called auxiliary or relay nozzles
Data Source
Figure 1
Figure 2
AI summary
The method involves having several measurement pickups, which are formed for multiple or continuous measurement within a weft insertion and is arranged after a thread centering device (23) provided at the outlet of a thread store (21), or after a thread brake (9). During the weft insertion measured values are measured in contact-free manner several times or continuously by the special measurement pickup (6, 6.1-6.5). The values determined during the weft insertion are used for the regulation and or control of the weft insertion and in particular for the current weft insertion. An independent claim is included for a device for inserting weft thread into a loom.