Computerized Air-jet weaving simulator

CHARACTERIZATION OF AIR-YARN INTERFACE IN AIR-JET
WEAVING

Abstract

We are building a computerized air-jet weaving simulator and developing databases to better understand fiber and yarn motion dynamics in air-jet weaving.

The yarn velocity measurements are performed with the fiber optic sensors attached on the profiled reed. The signal difference produced by the weft yarn entering the sensor is sent to the computer by data acquisition system and these signals are converted into time values by the LabView program. Then the velocity is calculated from time-distance relationship.

There are several parameters that affect receiving reliable data on this system. To receive more reliable data and minimize false signals, some improvements were made on the system.

EXPERIMENTAL

Two different filling insertion systems were constructed for experiments. Our main system has a profiled reed with a main nozzle, which inserts the yarn through the initial portion and 44 relay nozzles, which help the filling yarn continue its motion along the reed (Figure 1). With the data acquisition with computer interface, this system enables us to obtain data for yarn and air velocity. A tube guided simulator system with a single nozzle has also been developed.

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A LabView program is written to collect the time data in which the yarn travels through

the sensors along the reed.

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There are several parameters that affect receiving reliable data on this system. To receive more reliable data and minimize false signals, some improvements were made on the system, lately.

System Improvements

The weft storage system was a big challenge to receive consistent data. The capacity of drum feeder was not enough to support high running speeds and weft breakage was taking place very often. Moreover, the structure of drum feeder was not efficient to allow continuous yarn support and had great tendency to catch the yarn and cause tangling. Thus, two new accumulators were purchased which had higher storage capacity, electronic control availability and hand control device to program weft length, number of coils, etc. The connection of these electronic heads to the current Jet Control Unit system was also a challenge, since there was no example of this type of devices used together in industrial applications. The optocouplers on the Jet Control Unit system were used to make the connection between Jet Control and accumulators. To implement this, a new power supply unit was used. As a result, the synchronized motion of two accumulators was set on the Jet Control software.

Another parameter that affects receiving consistent data is the sensitivity of the sensors. Sensors are so sensitive that they can easily generate false signals due to their loose attachment on the reed and the vibrating motion of the weft yarn.

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The sensors were attached on the reed rather than mounted stiffly. Sensors tended to move during machine running time which caused sudden changes on light transmission levels. False signals were sent to the computer due to these changes, which happened regardless of yarn movement. This problem caused an additional obstacle. The sensor could give several false signals during the yarn insertion until the end of the pick leaves the sensor. When the distance between sensors were smaller than the insertion length, it was impossible to receive reliable data, since the end of the pick was followed by the second pick in a continuous manner.

On a real air-jet machine, the weft is taken into the fabric by the reed. However, on our simulator, the yarn is supposed to leave the reed completely, therefore weft yarn is sucked by the vacuum at the end of the reed.

The new accumulator system allowed us to control this problem. Both accumulators were programmed to work, one after another, with certain time intervals. More consistent and reliable data could be achieved by this way. Figure 4 shows the experimental system developed.

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