The tightness and tightness rate of fabrics with the same support surface in warp and weft
1. Compact structure fabric The discussion of fabric tightness is mainly given by considering only the projected area of warp and weft yarns without considering the interlacing of warp and weft yarns. Therefore, strictly speaking, it cannot truly represent the interlacing of warp and weft yarns in the fabric. The tightness of the arrangement. Because the interlacing of warp and weft yarns prevents the warp or weft yarns from moving closer to each other. For example, according to the concept of tightness, the warp tightness of any fabric can reach 100%. However, if the interlacing between warp and weft yarns is taken into account, then 100% warp tightness cannot be achieved in any structural phase. The following is a comparative explanation using the example in Figure 4-10. In these three figures, taking the warp yarns as an example, they have reached a state of great interlacing and arrangement, that is, the warp yarns can no longer get closer to each other. But it can be seen that their meridional tightness is different. Figure 4-10(a) is a plain weave with a meridional tightness of 100%; Figure 4-10(b) is also a plain weave, but the meridional tightness is less than 100%, and its structure is lower than that of Figure 4-10(a) ). Figure 4-1O(c) is a non-plain weave structure, and its meridional tightness is less than 100%. Its structural phase is different from Figures 4-10(a) and (b). It can be seen from Figure 4-10 that under certain structural conditions, a section of weft yarn interlaced with the warp yarn takes up part of the space, hindering the warp yarns from moving closer together, causing a gap between two adjacent warp yarns. The gap is shown as δ in Figure 4-10(b) and (c). In the same way, this phenomenon also exists in weft yarns. When the warp yarns do not intersect with the weft yarns, they are closely arranged with each other (the weft yarns form a straight segment). When they intersect with the weft yarns, the weft yarns are bent without a straight segment. This state indicates that the warp yarns in the fabric are arranged in a highly compact state when they are interlaced with the weft yarns. We call such a fabric a warp-wise compact fabric. In the same way, we can define weft tight fabric. If a certain fabric is in a compact state in the warp and weft directions, it is called a compact fabric in the warp and weft directions, or compact fabric for short. The tightness of fabric in a compact state is called compact fabric tightness, which varies with fabric organization and structure. Through analysis, it can be proved that under the same conditions of warp and weft spinning yarn density, no matter what kind of organization, only when the structural phase is greater than or equal to 7.9, the warp tightness can reach 100%. Taking 3/1 twill fabric as an example, the fabric structure is shown in Figure 4-11. From this, the formula for calculating the tightness of the warp and weft yarns with the supporting surface in regular fabrics can be derived, and the matching conditions of the warp and weft yarns can be found to Determine the warp and weft tightness (Ej, Ew) that the fabric should have.
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