Investigation Of Knitting Process And Liquid Moisture Transmitting Properties Of Double-faced Effect Functional Knitted Fabrics

The knitting process and liquid moisture transmitting properties of double-faced effect functional knitted fabrics is discussed in this paper. Via the analysis of the lapping character of single circular knitting machine, the practical horizontal and vertical lapping angle is introduced to determine the center track of yarn cross-section. The effect of cylinder diameter change on the horizontal lapping angle is analyzed. With the method of regression analysis the critical diameter of differentiating the small and large cylinder diameter is determined in the case of single circular knitting machine.The different cylinder diameter of circular knitting machine corresponds to the different lapping angle position. The knitting process can be completed by the needles in two ways: one is the needle tongue controlled by the old loop doesn't hit the yarns while rotating up and another way does. Corresponding to the two situations, the experiments are carried out on the small and large diameter circular knitting machine respectively. Through above discussion the rule of optimal lapping angle position can be derived, therefore the good plating effect can be ensured. Adopting above lapping angle position rules, the double-faced effect plated fabrics are knitted on the small and large diameter single circular knitting machine. The properties of liquid moisture transmitting are tested with the novel equipment MMT. The experiments testify that the fabrics with good plating effect and reasonable structure and density meet the requirement of the liquid moisture transmitting. The same experiments are carried out with double-faced effect fabrics knitted on the double circular knitting machine. A set of novel functional knitted fabric is analyzed from the two aspects of tactile and thermo-hydro comfort in the condition of liquid moisture absorption.The process of liquid moisture transmitting and diffusing in the single plated fabrics is simulated by digital technique. The simulation provides a novel emulational facility for the liquid moisture transmitting properties of functional knitted fabrics. In terms of the situation that the hold line of old loops is a curve in the practical knitting process of circular knitting machine, differently with the traditional theories, the paper enact the horizontal and vertical lapping angles on the small and large diameter single circular knitting machine. Using the lapping angles as independents the paper educes the following equations of yam cross-section track:The variation of cylinder diameter will affect the position of horizontal lapping angle. In the knitting process, the closing moment of needle tongue corresponds the cylinder rotating angleφ_c. The curve aboutφ_c changing with the cylinder diameter is showed and the ranges of horizontal lapping angle in different cylinder diameter machines are figured out basing on the yam cross-section track. The results prove that the size of needle hook plays an important role in the lapping angle range. On the other hand, the regression analysis about yam cross-section track in three kinds of cylinder diameter determines that 7 inch is the critical cylinder diameter. The single circular knitting machine belongs to the large diameter machine when its diameter is larger than 7 inch. The experiments confirm the reasonable agreements between above theories and practical knitting process.As for the needle tongue hitting the yams to knit the plated fabrics, the relevant lapping angle positions involve three situations through theoretical analysis and experiments: a. The needle tongue hitting the plating yams and ground yams. The lapping angle position of good plating effect isα_面＜α_面β_面＞,β_地(small cylinder dimeter) andα_面＞α_地&β_面＞β_地(large cylinder diameter), b. The needle tongue hitting the plating yams only. The ground yams turn out to the front surface of the fabric and the fabrics can not form the good plating structure, c. The needle tongue hitting the ground yam only. The lapping angle position of good plating effect isα_面＜α_地&β_面＞β_地in two kinds of machines.The double-faced effect plated fabrics with the structure of plain and tuck are knitted adopting the reasonable yam lapping angle position. The experiments tested by MMT prove these fabrics good liquid moisture transmitting properties. Choosing the cotton as the plating yarns and profiled cross-section polyester as the ground yams, the plated fabrics have the ideal capability of managing the liquid moisture transmitting. The fabrics with double-faced effect knitted on double circular knitting machine are also commonly used. Using seven kinds of double knitted fabrics designed for good moisture absorption and quick-dry properties and five kinds of designed fabrics with different structure, the experiments are carried out for comparing their liquid moisture properties. The results show that the effective way to improve the fabrics liquid moisture transmitting properties is applying the well-proportioned mesh distribution and befitting stitch density with the cotton and profiled yams. Namely, the yams material components, stitch density and fabric structure play the important role in the fabrics liquid moisture transmitting properties. Some fibers have hygroscopic expansion after the moisture absorption to different extent. So the yam diameter increases, especially the cotton yams, which results in the porosity decreasing and the fabrics capability of transferring the moisture reduced. However, the situation could be changed if using a novel functional fiber and special designed knit structure. The properties of the fabrics are improved from both tactile and thermo-hydro comfort.The application of digital technique provides a novel way to investigate the fabric liquid moisture transmitting properties. The dynamic transmitting process is simulated in a graphical user interface. Based on the analysis of the double-faced effect plated plain fabric structure horizontally and vertically, the transmitting area modify coefficient AF is introduced to the simulator program:AF=ζ~2·X·1/KWhere,ζis the structure zigzag coefficient, X is the orientation coefficient, K is the moisture retain coefficient. The paper compares the simulation results with the pictures gotten from screening the experiments results of plated plain fabrics. There are reasonable agreement between the graphics and pictures, which shows that the simulator program is precisely orientated and the modify coefficient reflects the fabrics character mostly. These results also denote the rationality of dynamic simulating the liquid moisture transmitting process with digital technique. The studies provide good foundation for further investigating the liquid moisture transmitting properties of more kinds of functional knitted fabrics.