【Popular science】Warp knitted fabric of knitted fabric
Editor: SunHing │ Date: May 07, 2021
Knitted fabrics can be divided into two categories: weft knitting and warp knitting according to the weaving method. There are science weft knitted fabrics in front. Today I will tell everyone about warp knitted fabrics.
Warp knitted fabric is a kind of fabric in which a group of yarns or several groups of yarns are drawn from the warp beam and placed on the corresponding knitting needles of the warp knitting machine along the longitudinal direction to simultaneously form loops, and are intertwined in the transverse direction.
/01/ The composition of the coil
Loop is the basic structural unit of knitted fabrics, and its geometric form presents a three-dimensional curved space curve. In the warp-knitted coil structure diagram, the coil is composed of leg1-2, needle loop2-3-4 and underlap5-6.
Three forms of coils in warp knitting organization:
Open loop: The extension lines of the coil base do not intersect each other.
Close loop: The extension lines of the coil base cross each other.
Double loop: A yarn is placed in front of two adjacent knitting needles at the same time.
/02/ The formation of warp knitted fabrics
Most modern warp knitting machines use slot needles (composite needles), and a few use crochet and latch needles. The basic principle of the warp knitting process is similar to that of the weft knitting method, and it is also divided into unwinding, backing, closing, There are eight stages of looping, bending, unlooping, looping and drawing.
On the warp knitting machine, the parallel-arranged yarns are drawn from the warp beam and pass through each guide needle. A row of guide needles forms a guide bar. The bar drives the yarn guide needle to swing back and forth between the knitting needles and to traverse the front and back of the needles, and the yarns are respectively wound on the knitting needles, forming a loop after forming a loop.
Because the stitches of one course are set with the corresponding stitches of the previous course, the course and the course are connected to each other. When the stitch on a certain needle is formed, the bar will move the yarn to other needles in a certain order to form a loop. At the same time, this constitutes the connection between the wale and wale of the coil.
The difference between warp-knitted and weft-knitted fabrics is that: weft-knitting is a loop-forming system in which one or several yarns are inserted into each knitting needle along the transverse direction to form loops in sequence; while warp-knitting consists of a group or Several groups of yarns arranged in parallel are inserted into a row of knitting needles along the longitudinal direction, forming a loop synchronously.
/03/ Classification of warp knitted fabrics
Like weft-knitted fabrics, warp-knitted fabrics are also divided into three categories: basic organization, change organization and pattern organization.
The basic organization is also called the original organization. It is the basis of all warp knitting organizations. It includes knitting chain, warp flat, warp satin and heavy warp weaves, as well as double-sided rib knitting chain, rib flat warp and rib warp satin weaves.
The change organization is composed of two or more basic warp knitting weaves arranged alternately, that is, between adjacent wales of a warp knitting basic organization, another or several warp knitting basic weaves are arranged to Change the structure and performance of the original organization. The changing organization of warp knitting consists of single-sided changing warp flat, changing warp satin and changing heavy warp organization, and double-sided double rib warp plain weaving.
The pattern structure is based on the change of the original warp knitting structure, using the change of the loop structure, the change of the inlay movement, or the addition of some yarns or other textile materials, etc., to form a pattern with a significant pattern effect and different properties. Fabric. Such as multi-bar warp knitting organization, jacquard warp knitting organization, double needle bed warp knitting organization and so on.
There are many factors that affect the structure and appearance characteristics of warp knitted fabrics, including the machine size of the warp knitting machine, the number of needle beds, the number of bars, the form of the cross movement of the bars, the type of raw materials, the threading and yarn alignment of the bars , In the complete organization, the traverse law of the guide bar and the average warp let-off per course, the density of the fabric, etc. Among them, the arrangement of the warp and the movement of the guide needle on the bar are important factors that affect the shape of the loop in the fabric.
/04/ Warp knitting process
In warping, the package yarn and bobbin yarn are wound on a cylindrical pan head according to the required length, number and other specifications, in order to save space.
▲ Warping machine
Weaving can be further subdivided into winding head → threading → adjusting machine → starting production.
▲ Threading process
/05/ Types of warp knitting machines
● According to the needle bed, it can be divided into single needle bed warp knitting machine and double needle bed warp knitting machine.
● According to the structure and function of the machine, it can be divided into Tricot warp knitting machine (also known as high-speed warp knitting machine) and Raschel warp knitting machine (also known as fancy warp knitting machine).
The following are two models produced by Karl Mayer, Germany, the world's largest manufacturer of warp knitting machines.
▲ Tricot machine（ HSK 2-SE )
▲ Raschel machine ( RSE4-1 )
The difference in appearance and structure. The position of the pan head is different: the pan head of the Raschel machine is at the top; the pan head of the Tricot machine is behind the top machine.
The internal structure is different. The difference in the structure of the sinker leads to the difference in the way of cloth rolling between the two.
Raschel machines use aluminum tubes to roll cloth, while Tricot machines mostly use cannon rolls. The fabric lead-out angle of Tricot warp knitting machine is 90~115°, and the lead-out angle of Rashel warp knitting machine is 130~170°.
/06/ Features of warp knitted fabrics
● The fabric performance is between the weft knitted fabric and the woven fabric;
● The warp knitted fabric has good anti-scattering performance;
● Suitable for weaving mesh structure;
● Suitable for knitting plush fabric;
● High production efficiency (up to 3300r.p.m, 210");
● High requirements for raw materials, production machinery and production environment, requiring constant temperature and humidity.
/07/ Application of warp knitting products
Warp knitting products are widely used in clothing and decoration fields, and they are also widely used in industrial fields. Such as underwear, shapewear, swimwear, lace, high-end knitted shirts, coral fleece, curtains, warp-knitted geogrid, warp-knitted vegetation mesh, car cushions, car interiors, medical bandages, artificial blood vessels, etc.
From the beginning of warp knitted fabrics to only mosquito nets, to nowadays lace, high-end warp knitted fabrics, home textiles, artificial satellites, medical artificial blood vessels, building materials, etc., warp knitted fabrics can be seen everywhere.
At present, the warp knitting industry is not much distributed in China. It is generally concentrated in the Pearl River Delta of Guangdong, Shantou of Guangdong, Changle of Fujian, Jinjiang of Fujian, Haining of Zhejiang, Yangxunqiao of Zhejiang, Changshu of Jiangsu, Suxichang of Jiangsu, etc. The relatively mature weft knitting technology is still There is a lot of room for development, and it is believed that the warp knitting industry will usher in an era of blossoming flowers in the future.