Theoretical And Experimental Study On Weft-knit Platting Technology

With the development of knitting industry and new fiber materials, more and more weft-knit platted fabrics are used in the fields of clothing, decoration and technical textiles, especially in the functional underwear, casual knits and medical textiles. These platted fabrics produced in circular and flat knitting machines characterize the properties of both plating yarn and ground yarn and have the color effects on both sides. During the production of platted fabrics, there are many factors influence the fabric quality and platting effects such as physical and mechanical properties of fiber and yarn, feeder construction and position, needle shape, knitting action, tension of yarn feeder supply and drawn-off mechanism etc. It seems the traditional plating theory cannot be completely applied to the large diameter knitting machines. At present, most researches on it are focusing on the plating technique and properties of the newer platted fabrics, and seldom relates to the foundation research and evaluation of misplating degree. This paper mainly researches on the theory of plating stitch formation during the yarn laying and analyses the factors affecting on the plating effects by experiments. This paper also develops a new kind of testing software for fabric misplating evaluation by means of computer. The aim of this study is to complement the traditional plating theory and plating techniques. It has both significant meanings and practical values for applying platting knitted fabrics to clothing, decoration and technical textiles end uses.The research methods of this paper include theoretical analysis, experiments study and testing methods establishment. Using the Space Analytic Geometry Principle, this paper deduced the formulas of yarn cross-section track during the yarn laying of platted loop formation, reveled the regulation of platting and ground yarn cross-section tracks both of 15 and 30diameter circular knitting machine and showed the meeting position of these two yarns at the hook of latch needle given by formula and figure respectively. The calculation formulas of yarn laying angles as well as critical values at vertical and horizontal planes were also deduced in this paper. On the experimental research, this paper discussed the factors affecting the misplating problems such as yarn properties and loop length on circular knitting machine and yarn feeder, knitting technique and fabric structures on flat knitting machine respectively. On the testing method and misplating evaluation study, this paper developed a new kind of testing software especially faster measuring misplating degree of platted fabrics by means of Visual Basic. Summarization of this paper, some useful conclusions are as follows.The regularity of two yarn cross-section tracks produced from 15 and 30 diameter circular knitting machine is liner, and the regression coefficients both of large diameter circular knitting machine and ground yarn are larger than that of small diameter and plating yarn respectively. These two kinds of knitting machines have different yarn laying angles showing α_p<α_G , β_p<β_g for small diameter and α_p<α_G β_p<β_g for large diameter where small marks P and G represent plating yarn and ground yarn respectively. The formula values of yarn laying angle is consistent with the testing data. Within the range of plating technique, the more separate of two yarn tracks, the well plating effect can be obtained.There are many factors affecting platting effects of platted fabrics. On the circular knitting machine, the sequence of strong influencing is stiffness coefficient > rub coefficient > yarn count. The stiffness of plating yarn should be smaller than that of ground yarn, but the rub coefficient and loop length are on the contrary. On the flat knitting machine, the construction and adjustment of feeder has very important to the plating quality. The modified feeders can greatly improve the accurate plating. The feeder should be positioned vertically above the needle bed and located at a suitable height. Within the ext...