In the weaving, the warp yarns are subjected to a variety of forces and complex deformation occurs. From the basic movement of the loom:
(1) When the opening is moved, the warp yarn is bent into a fold line at the eye of the eye by a substantially flat heald, and an elongation proportional to the square of the height of the shed occurs. At the same time, due to the asymmetry of the front and rear lengths of the shed, the warp yarns slip in the eye, causing friction. When the upper and lower warp yarns are alternately moved up and down during the opening movement, intense friction occurs between them.
(2) During the weft insertion movement, the shuttle of the shuttle loom is supported by the shed, and the friction is traversed therebetween, especially when the shed is in and out, the warp of the side is greatly squeezed, causing bending, elongation and friction. The weft guiding components of the shuttleless loom also have considerable friction against the warp yarns.
(3) When the beating motion is performed, the warp yarn at the front of the shed is rubbed by the reciprocating molars. Due to the shrinkage, the pressing friction of the caries and the side warp yarns is more severe. In the weft-blowing area, the back-and-forth movement caused by each beating will increase the friction between the warp and the eye.
(4) During the warp and take-up movements, the warp yarns on the weaving shaft always have a certain braking tension when they are sent out. Most of the existing let-off mechanisms belong to the tension-adjusting and let-off mechanism, and the amount of warp is controlled by the sensing feedback of the warp tension. Therefore, when a warp yarn with a weak knot passes through the back beam, it begins to break. The take-up motion also affects the warp tension, and forms a warp elastoplastic deformation system with the warp, beating, and opening.
It can be seen that the force and deformation of the warp yarn during the weaving process are mainly formed by tension (required not to cause breakage), elongation (cycle deformation can be recovered) and friction (no fuzzing, pilling, grinding).
At the same time, it is worth paying attention to the problem of hairiness. In the warp opening, the protruding hairiness will entangle each other, making the opening unclear, resulting in difficult to eliminate the yarn skipping, flower jumping, hanging and other defects. In the weft insertion of the air jet loom, the unclear opening causes the weft yarn to block, which is the main factor affecting the efficiency. Therefore, reducing hairiness is an important indicator.
In view of the above, in order to improve the weaving performance of the warp yarn, an effective method adopted in the weaving preparation process is sizing. That is, the slurry to which the adhesive material is applied to the warp yarn acts on the surface of the warp yarn to a certain depth, and after drying, a sizing structure in which the pulp and the yarn are integrated is formed.
The impregnation of the slurry causes the fibers in the sizing to adhere to each other, increasing the breaking strength. However, the fiber elongation does not easily slip to each other, and the elongation at break is reduced. The coating of the slurry forms a protective layer on the surface of the sizing surface, so that the hairiness protruding from the surface is applied and can withstand friction without causing pilling, pilling or disintegration of the fibers to break.
Both the penetration rate and the coverage rate should be taken into consideration, and the different yarns should be emphasized. The serosal integrity rate is usually required to be above 75%.