| Electronic warp let-off device is the key part of air-jet loom, and its main function is to let the warp with suitable tension and make the tension constant. Electronic warp let-off decide the quality of the fabric, which will be the main study direction in future.The component of the electronic warp let-off and the study status and trend were introduced in this paper first. And then, three traditional evaluation methods of electronic warp let-off device were introduced.Dynamic tension could embody the real performances of electronic warp let-off device, so, exact dynamic tension acquisition is the key of this subject. Digital test system was used to obtain the dynamic tension. The test system is composed of tension sensor, standard bridge, dynamic resistance strain gauge, A/D digital data acquisition card, PC record equipment. The tension F on the sensor has linear relationship with the output voltage AU which is F=10â–³U. On base of these, warp tension was embodied by the voltage. The dynamic warp tension was analyzed with tension wave, probability density function of warp tension in this paper. It is easy to found out the beating tension and heald level tension from the tension wave. Probability density function shows that the most reasonable distribution of warp tension is normal distribution.Then, three indexes, warp tension stability and consistency, dynamic warp tension constancy from big beam to small beam, dynamic warp tension reversibility when starting, were proposed to analyze the electronic warp let-off device of three kinds of air-jet loom. Stability of electronic warp let-off device of two kinds air-jet looms was analyzed respectively while weaving different specification fabric with the tension fluctuation stability and consistency. The tension stability and consistency was embodied by tension range rate and similarity respectively. The results show that the tension range rate was below 10% while Picanol air-jet weaving two different specification fabric. And the least similarity was 0.97 and 0.96 respectively. Furthermore, tension range rate of air-jet loom was below 10%. And the least similarity was 0.97 and 0.95. The warp tension fluctuation stability and consistency of Picanol and JAT air-jet loom is better. Therefore, the performances of electronic warp let-off devices of two kinds of air-jet loom are stable. According to compare the tension fluctuation stability and consistency of three kinds of air-jet loom, the results were proposed that the performance of Picanol air-jet loom is the best and Surprise air-jet loom is the worst.About the control ability of warp let-off device to keep warp tension constant, three special warp tensions were analyzed to embody the control ability. The smaller the tension change rate is, the better the warp tension constancy is. Picanol air-jet loom and JAT air-jet was selected to compare their adjustment ability to warp tension constancy. The results show that the tension change rate of two air-jet looms was is about 20%. However, the tensionchange rate of Picanol is bigger than JAT air-jet loom, which shows that adjustment ability electronic warp let-off device of JAT air-jet loom is better than Picanol air-jet loom.At last, the adjustment and control performance of warp let-off device of three kinds of air-jet loom was compared with the warp tension reversibility while the loom starting. The adjustment and control performance of warp let-off device was measured with the tension recovery time. According to the analysis of tension reversibility, three conclusions were obtained. The recovery time of Picanol OMNI-190, JAT710 air-jet loom and Surprise air-jet loom is 2.64 seconds, 3.29 seconds and 3.74 seconds respectively. And their recovery time is some short. These results show that the adjustment and control performance of warp let-off device of Picanol air-jet loom is better than other two kinds of air-jet loom. And the adjustment and control performance of warp let-off device of Surprise air-jet loom is the worst. |
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