Solution to Weft Bending and Crimping of Elastic Denim
Elastic denim, which was honored as a new product in the early years, has become a common ordinary denim. The problems of excessive weft bending and crimping are common in the production process of elastic denim, which can be said to be two stubborn diseases in the production process of denim. In particular, the problem of excessive weft bending often causes the tailor to twist and deform, causing customers' quality complaints. In this regard, we have always lacked outstanding countermeasures. For crimping, we used to only use bamboo clips to clamp the cloth edges, but the demand for labor increases, and sometimes we still can't handle it. So how can we effectively deal with the above two problems? In this paper, denim manufacturers will discuss with us the ways to deal with the above problems from the aspect of equipment transformation.1. Causes of weft bending and crimping(1) Weft bendWeft bend is the shape that the weft yarn at the cloth opening of the product is arched, convex or concave. Its manifestations generally include three kinds: arched weft bend, lateral weft bend and wavy weft bend.Although weft bending generally has three forms, the principle of its occurrence is the same, which is formed because of the uneven force on the cloth surface. In the production process of elastic denim, because of the existence of elasticity, the change of cloth surface tension is greater than that of non elastic cloth, so it is easier to have excessive weft bending than non elastic cloth.(2) CrimpingCrimping is the phenomenon that the selvage is naturally shortened and rolled up to the cloth body. The primary reason for crimping is that the natural shortening of elastic yarn is much greater than that of non elastic yarn. If the thickness difference between the selvage and the cloth body is large, perhaps the selvage organization will be loosened due to poor selvage locking, and so on.2. Influence of weft bending and crimping on product qualityExcessive weft bending will directly lead to bone twisting and deformation of denim tailor after washing. It is the connotation quality problem of product cloth, and will cause customer complaints and claims. Crimping will cause the width to be out of control and can not meet the width requirements of the product. It will also make the humidity at both ends of the cloth too large and the center can not be unified to form the color degradation at both ends. In addition, crimping will also make it difficult to measure the weft slope, so that the weft can not be adjusted according to the process requirements. Similarly, it will also cause bone twisting after tailoring, which will seriously affect the connotation quality and appearance quality of the product.3. Treatment of excessive weft bending and crimping of elastic denimFor some time, customers complained repeatedly about the bone twisting of a tailor of a variety of elastic denim. Many times the tailor twisted the bone because of the poor weft finishing after cleaning, but we verified that the weft finishing quality in the workshop reached the range of process requirements through investigation. What is the cause of bone twisting? We focused on the problem of weft bending and found that the weft bending of this variety of products was relatively large, and some reached 3.5cm. In order to prove the influence of weft bending on tailor's bone twisting, we have done repeated sample washing experiments. From the analysis of experimental data, under the condition of the same weft slope, the product cloth with weft bending more than 2cm deforms greatly after washing, and the phenomenon of bone twisting simply occurs.While solving the problem of excessive weft bending, we also studied the problem of easy crimping of elastic denim. It is found that the crimping is also improved after roll bending, so we further track and analyze the effect of roll bending on crimping. Because the bending roll is convex in the middle, when the cloth passes through the bending roll, it seems that there is an external force pulling away from the middle of the cloth to both sides, so the crimping tends to open to both sides. However, this external force is far from enough to solve the crimping, so we think of the thread distribution roller. The thread distribution roller is separated from the middle, and the left and right sides have opposite left and right threads respectively. In this way, when the thread distribution roller rotates, wave after wave of spiral external thrust will be generated from the middle to both sides to pull the cloth from the middle to both sides, This prevents the selvage from shrinking and winding to the cloth body.