Conference_programme: 23: Structural acoustics and vibration

Lecture: Acoustic sensing of an interlaced yarn in a noisy industrial environment

Author(s): Bertolla Maddalena, Scotoni Mario, Caldara Mauro, Giacomelli Gianmarco

Summary:
Interlacing is a key process employed in textile industries to impart cohesion to multi-filament yarns. In an interlacer a continuous air jet impinges on a parallel yarn running through a channel (2000 m/min). As a result, filaments are intermingled with each other, producing an interlaced yarn with periodic opening and tangling parts. These cohesion points, called knots, are required since a parallel multi-filament yarn is more likely to separate or break during post processing, such as winding, weaving and knitting. \nThe knots distance needs to be regular to guarantee the homogeneity of the final fabric. However, even if the process is periodic, not-interlaced segments occur without a clear reason, since the dynamics of interlacing has not been fully understood yet. Therefore, a cheap on-line counting technique is required in order to monitor and improve the regularity of interlacing during yarn production. \nWe investigated and compared different approaches to monitor on-line the process: high speed imaging of the knots formation, analysis of the vibrations induced by interlacing and acoustic measurements. Regarding the acoustic sensing, we expected that the knots of the running yarn cause a periodic pressure variation in the surrounding air with a corresponding peak in the FFT of the acoustic signal. We managed to detect that weak signal over the industrial noise, removing higher frequency components through acoustic filters. Then, we processed the signals obtained from microphones placed along the yarn in different positions and configurations. Increasing the yarn speed, we observed a shift of the identified FFT peak, confirming in this way that we are detecting the frequency of interlacing and hence the knots distance. \nThis is the first example of a cheap acoustic sensing technique employed to monitor the interlacing process in textile industries.

Corresponding author

Name: Ms Maddalena Bertolla

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Country: Italy