| Warp-knitted spacer fabric is very different from the woven fabric and weft knitted fabric which consists of a bottom layer, an upper layer and a middle layer and then the spacer wire connects the upper and bottom layer. Because of the special construction, this fabric used for shoes has a good properties of air permeability and moisture conductivity and ensures air circulation and help sweat move quickly to create the interior of the shoe fresh air micro-environment. But in the actual production process, due to the weaving, stereotypes, and other process, it doesn’t guarantee that the interval wire connecting the two surfaces is always in a straight state. After processing into finished fabric, the wire spacer of some fabric appears collapse phenomenon, affecting the requirements for fabric thickness. This result intuitively reflects in the thickness of the fabric, but the fabric dimensional stability and cushioning effect of external forces will decline, which will significantly affect product performance. In addition, many companies when such fabrics are ignored compression performance test only think about aspects of approximate thickness requirements, but did not give a corresponding relationship between them, which is not reliable for spacer fabric performance evaluation. It is necessary to analyze for the influencing factors of thickness and compressibility performance of the fabric, and explore the relationship between them to guide production practices.This paper mainly does some researches of warp-knitted spacer fabrics in conjunction with the actual production process of the shoe factory. Firstly, using warp-knitted spacer fabric thickness of each process in a preliminary test find the main impact of the process; The main topic of the shoe factory in conjunction with the actual production process warp-knitted spacer fabrics, each process using warp-knitted spacer fabric thickness of each process in a preliminary test find the main impact of the process; and then using the control variable method of knitting and styling design experiments, changing the process parameters of the fabric to obtain test samples required for analysis; Finally, through thickness and compression performance testing of the fabric which changing process parameters, the relevant curve can be made to analyze the relationship between the thickness and compression performance among the parameters, obtaining the following conclusions:① Analysis of six different mesh size of t surface texture fabrics, its horizontal density variation within 4 wales per inch, vertical density variation within 12 courses per inch, when given horizontal density stable and vertical density increasing, the thickness of the fabric is constantly increasing; but when given vertical density stable and horizontal density increasing, the thickness is at the beginning and then goes to a decreasing trend. Meanwhile, each of the fabric in this density range thickness variation exists in stable density values, and the variation in thickness is greater than when the horizontal density variation changes the lengthwise density varying thickness.② Analysis seven fabrics with intervals tissue changing, including the I-shaped, V-shaped, X-shaped and other shapes. Observing the trend curve of the varying thickness found that the larger the gauge number of intervals tissue, the smaller the thickness of the fabric, and closed coil relatively larger thickness of the fabric than opening coil, but racking pitch has a more important impact on fabric thickness.③ Analysis the small mesh fabric when horizontal density is 26.5 wales / inch with varying the vertical density variation from 34-40 courses / inch and then variable density is 36 courses/ inch given varying the horizontal density variation from 23.4-27.4 wales / inch and through variable density of the fabric different pressure curves found that the presence of both quadratic relationship between density and rate of change in the thickness of the fabric under different pressures, is met: Y = AX2 + BX + C, where X represents the density of the fabric(vertical or horizontal density), Y represents the fabric thickness variation rate. When changing variable density, the reliability factor of the fitting formula is greater than 0.8. However when changing the horizontal density, the fabric that is only in a small pressure when 2/3/5KP, is more in line with the above curvilinear relationship, and the value of the reliability factor is also greater than 0.8; when the pressure is greater than 5KP and less than 50 KP, the secondary correlation between the horizontal density with the thickness change rate of fabrics is not very good.④ Analysis the small dense mesh fabric compression graph with the surface horizontal or vertical density changed found that the test results is similar to the fabric thickness test. When the horizontal density changing from 23.4 to 27.4 wales / inch and the vertical density changing from 34 to 40 courses / inch, the difference of the compression curve when its horizontal density changes is greater than when the vertical density changes. And the compression work and secant modulus of the initial portion of the fabric are increased during the first horizontal density variation and then reduced, but it has been increased at the vertical density changes. It shows in this density range, compression performance of this fabric with fabric horizontal density becoming larger first increases and then decreases, but with the vertical density becoming larger is increasing.⑤ Analysis the pressure thickness curve of five different mesh size fabrics discovery that the pressure put in the fabric has a quadratic polynomial relationship between fabric compression pressure and the thickness of the reciprocal of the square, that is Y = AX2 + BX + C(A> 0, Y represents the pressure that is subject to the force per unit area on the fabric, X represents the inverse of the square of the thickness of the fabric), but when the pressure is within 5KP range, these two factors has the approximate linear relationship between each other.⑥ Analysis the pressure curve of fabrics of two different mesh size and the thickness range from 1.8mm to 4mm found that when the pressure is 50 KP during the fabric compression process, there is a similar curvilinear relationship between the original thickness of the fabric and the compression work or hysteresis function: Y = AX2 + BX + C(where, A> 0, Y represents fabric compression work or lagging reactive power, X represents the value of the thickness of the fabric), the value of reliability factor is all greater than 0.8. It shows by adjusting the tension of the fabric to increase the thickness in fabric setting stage, the fabric is conducive to getting better compression performance, but at the same time increasing the lagging reactive power will make the fabric compression recovery rate decreased, which is unfavorable for the fabric elastic recovery.In summary, the main solution for lodging problems can be addressed when weaving and fabric setting stage. Choose a small number of crossing gauge monofilament tissue or tissue veil, when the thickness in force is in favor of a stable value, and can also increase the compressive properties of the fabric as well as improve the dimensional stability of the weaving. In fabric setting stage, due to horizontal density of the fabric has a bigger influence in thickness changing then longitudinal density, it’s beneficial to adjust the vertical density to reduce the lodging rate. Meanwhile, with the vertical density increases, the thickness of the compressive properties of the fabrics is also increased. In addition, the conclusion six shows that within the range of variation in thickness after changing the density of the fabric at the setting stage, compression performance of fabric is better with thickness increasing, but resilience is reduced. That Illustrates the relationship between compression performance and variable thickness during fabric setting stage can not only be characterized by the thickness values, which needs for further research. |
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