Weft Thread Stretching Device for Tension Control in Weaving Machines
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Solution Overview
Problem
Existing weaving machines face challenges in holding weft threads with sufficient tension without using catching threads, which can lead to pulled-back threads and potential damage during the weaving process.
Innovation Solution
A device comprising a stationary weft thread stretching device and a moveable guiding device positioned on the sley, which limits transverse displacement and directs the caught weft thread into a holding device with an entry slit, ensuring reliable transfer and tension maintenance, while avoiding interference with the reed and warp threads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If catching threads are used to hold weft thread tension, then the weft thread can be held with desired tension, but the catching threads may interfere with the reed and warp threads during insertion
Solution Approach 1:
The patent removes the catching thread mechanism entirely and replaces it with a suction-based weft thread holding device. The suction device extracts and holds the weft thread end directly without requiring separate catching threads, thereby eliminating the interference problem while maintaining tension control
Solution Approach 2:
The patent employs a suction device that uses pneumatic pressure differential to catch and hold the weft thread end. The suction device creates a negative pressure zone that securely holds the weft thread without mechanical contact, avoiding interference with the reed and warp threads during the insertion process
2Manufacturing precision
If the guiding device is positioned close to the reed for effective guiding, then the weft thread can be directed accurately, but the guiding device may interfere with weft threads during insertion
Solution Approach 1:
The guiding device is designed to move dynamically with the sley during the weaving cycle. By synchronizing the guiding device's position with the sley motion, the device can effectively guide the weft thread at the appropriate moment while retracting or moving away during the insertion phase to avoid interference with the reed and warp threads
3Device complexity
If a stationary weft thread stretching device is used, then the device structure is simplified, but the weft thread may experience transverse displacement during guiding
Solution Approach 1:
The moveable guiding device acts as an intermediary between the stationary stretching device and the weft thread. The guiding device transfers the weft thread from the stretching device to the holding device while maintaining proper alignment, preventing transverse displacement without requiring the stretching device itself to be moveable
Solution Approach 2:
The solution addresses the positioning stability issue by introducing motion in a different dimension - the guiding device moves along the insertion path direction while the stretching device remains stationary. This dimensional separation allows the stretching device to maintain simplicity while the guiding device compensates for position stability through its motion
Data Source
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AI summary
Device and method for catching and stretching a weft thread (2) inserted into a shed of a weaving machine, wherein a weft thread stretching device (7) is arranged stationary on the weaving machine in an extension of an insertion path of the weft thread (2) and a guiding device (10) is adapted for limiting a displacement of the caught weft thread (2a) in a direction transverse to the moving direction of the guiding device (10) upon guiding the caught weft thread (2a) towards the weft thread holding device (9). Weaving machine with such a device.