The Study On Controlling Density Specific Weight Of The Weft Knitted Fabric

The weft knitted fabric is favored deeply by consumers with fine elasticity, the flexibility, the permeability, easy to maintain and so on. Most enterprises in our country export products by processing the material or fabric offered. It is extremely essential to control knitting technology. Density specific weight, also called weight per square meter, is a comprehensive factor, directly affects physical property of the fabric and comfortable performance, decided the fabric intrinsic quality and related to the profit of enterprise. However, many factors which exist each process affect density specific weight, and the key problem is difficult to control. To find the effect factors and propose the improvement measure and make density specific weight on the reasonable control, materials, the knitting, dyeing and finishing technology were studied in this thesis.To make foundation of the following study the properties of the yarns were tested, which included the fineness and the deviation of the pure silk and cotton yarn, and analyzed their shrinkage under the different temperatures. It showed that the pure silk has higher thermo-hydro shrinkage, which is increasing remarkably with the increasing of the temperature of water bath. The results provide reference to control density specific weight in the process of weaving and dyeing more accurately.The cloth sample being knitted was tested completely, test data shows the relationship between some factors and fabric density specific weight, including the gauge, yarn linear density, loop length, fabric construction, and some other factors also influence specific weight. In order to control fabric density specific weight, we can adopt the way to control loop length. On the base of loop and fabric construction, we brought forward the concept of perfect loop length. We summed up several normal methods of controlling loop length in paper, and proposed a new method by loop length monitor which haven't to touch the yarn and can control loop length effectively. Many experiments showed the new way is superior to traditional methods.The relation between the dyeing and thermosetting technology of pure silk knitted fabric and fabric density specific weight was studied in this thesis. As the result of different dyeing technology, the different fabric structures leaded to specific weight change of varying degree, and also existed instability. With the help of orthogonal experiment, the optimal thermosetting condition was obtained, which profit both of fabric density specific weight and shrinkage rate.