Denim is a difficult fabric to weave, which is mainly determined by its style characteristics. The style characteristics of denim are expressed in two aspects, namely, the blue-white color and light style and the close and thick structure. The color and light style of blue and white is achieved by interweaving indigo dyed warp yarns with the weft yarns of the original color, and forming a special effect on the surface of the fabric by the floating point of the color warp and the floating point of the white weft in a certain proportion through the specific organizational structure and the specific parameters of the organizational structure. Organizational structure is tight and thick because of the high tightness of denim fabric, such as ordinary medium and heavy denim fabric tightness in 94% or more, and tightness of the same great khaki fabric tightness is only 85% or more. Denim fabric structure tight style characteristics decided its weft yarn is not easy to tighten, weaving difficulty is high. In recent years, a variety of raw materials continue to be used in the development of new varieties of denim, such as the popular gold and silver series of denim, weft filament series, Tencel series, etc., have their own characteristics, how to weave a variety of denim of excellent quality, to solve the weaving process of the quality of the various problems that have arisen in the process of the new direction of research.
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Denim Style Characteristics Of Weaving Requirements
Weaving conditions of bad configuration, such as warp and weft yarn tension adjustment is not appropriate, the warp axis of the loose, tight warp, loom downtime and so on will change the denim color warp, white weft floating point composition of the proportion of change, affect the blue through the white fabric style, and easy to reveal blemishes in the fabric, affecting the quality of the fabric.
Denim thick, tight structure style characteristics, need a reasonable configuration of the opening time, the position of the back beam, the warp yarn on the machine tension and other on-machine conditions can be realized. The opening time directly affects the style of denim fabric. If the opening time is early, the bobbin angle at the weaving mouth is large, and the weft yarn is not easy to be reversed after weaving, which is conducive to tightening the weft yarn to achieve the effect of compactness, thickness and flatness of the cloth surface. Late opening time, weft weaving at the mouth of the bobbin angle is small, the warp yarn on the weft yarn holding angle is small, is not conducive to the composition of compact fabrics. Therefore, the general use of early opening process. After the beam process using a higher back beam, the purpose is to increase the difference between the upper and lower tension of the warp yarn, the weft yarn is easy to weave into the weaving mouth, reducing the resistance to beat the weft. However, the position of the back beam should not be too high, otherwise the upper layer of warp yarn tension relaxation, the shuttle mouth is not clear, while the lower layer of warp yarn tension is too large, resulting in hopping, warp yarn breakage and other defects. The position of the back beam should take into account the appearance of the fabric requirements. Too much tension on the machine, the warp yarn is prone to plastic deformation, resulting in warp shrinkage defects; too little tension on the machine, it is not easy to weave tight and thick fabrics. General use of large tension weaving, to meet the strong denim fabric weft requirements.
Denim fabric by increasing the warp yarn bending wave height to obtain the fullness of the thick structure and the fabric’s unique style. The fullness of the fabric is related to the degree of bending of the yarns in the fabric. In order to realize this style characteristic, high demands are placed on the loom.
The Development Of Looms For Denim Weaving
With the pursuit of high value-added products, the market is more inclined to develop high-grade denim fabrics. To weave high-grade denim, the requirements of the loom should have advanced driving marks processing function, sturdy frame, strong weft force, larger winding force and the warp yarn to send out the tension to be uniform, easy to maintain, variety of adaptability and other technical requirements.
Shuttleless loom a lot of electromechanical integration technology, the use of a variety of automatic adjustment, electronic control devices, etc., can effectively reduce the defects in the weaving, coupled with shuttleless loom weft speed, large rolls loaded with mixed weft for weft, greatly reducing the generation of weft defects; the use of conjugate cams to fix the reed to beat the weft to ensure that the weft force to meet a variety of types and grades of denim fabric weaving. Used for weaving denim shuttleless loom mainly has rapier loom, piece shuttle loom and air jet loom.
Rapier Loom Weaving Denim Features
The imported rapier looms used in denim production factories are mainly as follows: GAMMA rapier loom of Belgium Picanol Company, TP500 rapier loom of Italy Smit Company, SM93 rapier loom of Somet Company, LT-102 rapier loom of Japan Toyota Company, rapier loom produced by Switzerland SULERRUTI. Rapier weaving machine for denim fabrics. Rapier loom weaving denim has the following characteristics:
- Adoption of conjugate cam-type weft-beating mechanism. Denim weaving requires a large weft force, the use of conjugate cam type weft mechanism, the weft force can reach more than 9.8N/cm.
- Adopting electronic warp feeding and electronic winding to realize constant tension weaving. By detecting the change of warp yarn tension and warp diameter to maintain a stable amount of warp feeding, and can automatically adjust the warp yarn tension according to the characteristics and requirements of the fabric, weaving tension fluctuation is less than 2%, effectively avoiding and reducing the sparse road defects, to ensure that the denim fabric surface is clear, flat, and has a glossy finish.
- Equipped with warp and weft breakage positioning self-stopping device, and some of them have digital control automatic compensation function. When the warp or weft yarn breaks, the loom can realize the positioning self-stop, different time compensation and driving compensation after stopping the warp, different number of weft yarns after stopping the weft and driving compensation. These compensation functions can reduce the driving stalls and prevent warp shrinkage or thinning stalls caused by warp yarn deformation due to long stopping time, which is conducive to the improvement of fabric quality. In general, double back beam, double side conjugate cam wefting is more conducive to weaving heavy denim, to ensure that the cloth surface is full, feel good, glossy; weft force is large, to ensure that the cloth surface is tight, clear grain; small openings, short process, short reed foot wefting is conducive to improving the speed of the weaving machine; positioning and stopping and automatic weft searching can effectively reduce the weft defects and driving gear.
