Is the drawing process management calculation or drawing calculation?

In the process design, process calculation is needed, which mainly includes the density, loop length, let-off ratio, square meter weight and output of warp knitted fabric.

I. Density

The density index is usually given by the grey fabric specification. When trying out new products, it should be decided according to the experimental process or the needs of customers.

Transverse density PA: expressed by vertical rows per cm (or vertical rows per 5 cm). PA depends on the number of warp knitting machines and shrinkage. Therefore, when the formed loop spacing is approximately equal to the knitting needle spacing:

Longitudinal density PB: also expressed in lines per cm (or lines per 5 cm). PB is related to coil length, yarn count and gram weight per square meter. When other parameters are known:

Where: Pb 1- vertical density (horizontal row/? )

Pa 1- horizontal density (vertical/? )

Li-i-th strip coil length (? )

Tti—— linear density (Tex) of raw materials used for the I-th guide bar.

Q- Gram weight per square meter of fabric (g/m2)

Pi -- the empty penetration of the first I steel bar

M- number of all guide rods

Considering that in warp knitting production, the density is often expressed by the number of loops of 5 cm, so the longitudinal density can also be calculated according to the ordinary number of branches in the above formula:

Where: PB2-vertical density (row /5? )

PA2-horizontal density (vertical /5? )

Li-i coil length (? )

Nmi-the number of I-th combed yarn

Q- Gram weight per square meter of fabric (g/m2)

Pi -- the empty penetration of the first I steel bar

For a kind of clothing grey fabric, if the front side is completely penetrated by 2.22tex nylon yarn and the back side is completely penetrated by 16.67tex textured polyester yarn, the loop length is 4.5mm, the let-off ratio L1:L2 is 0.75, and the transverse density PA= 10/? , the weight of grey cloth per square meter180g, then:

Both combs are completely worn, and the vacancy rate P is 0.

2. Weight of grey cloth per square meter

In the case of article m:

The unit in the formula is the same as that in the previous formula PB 1, and q can also be expressed as:

Take the grey cloth with double comb headscarves as an example. The horizontal density is PA 1= 1 1 vertical row/? Vertical density PB 1= 18 rows/? The front and back combs are made of 2.22tex nylon yarn, the air permeability is 6/34, and the coil length is 2.9mm, then:

Q = 2×10-2× 2.9× 2.22×16×18× (1-6/34) = 20.995 = 21(g/m2

Take interwoven shirt grey cloth as an example, PA 1= 1 1 vertical arrangement/? , PB2=23 lines/? The front comb is all 3.33tex nylon yarn and the back comb is all 8.33tex polyester yarn, with a loop length of 3.4? , the let-off ratio is 0.7, then:

Q =10-2× 0.7× 3.4× 3.33×1× 23×10-2× 3.4× 8.33×1/kloc-0 /× 23 = 9/kloc.

From this example, we can also see a simple calculation method of the ratio of two yarns. Let the above formula Q=A+B, and these two terms A and B are actually the weights of the front combed yarn and the rear combed yarn within one square meter respectively. Therefore, the dosage ratio of 3.33 nylon yarn should be:

The substitution value is 2 1.9%. Similarly, the percentage of 8.83tex polyester yarn should be:

The substitution value is 78. 1%. Of course, as we all know, the percentage of one of the two raw materials to the other can also be:

8.33 percentage of special polyester yarn =1-21.9% = 78.1%.

3. Coil length and let-off ratio

In process design, the coil length is very important. Generally, the coil length can be calculated according to the given grey cloth specification, and the following formula can be used at this time:

Where: lK-the coil length of the kth comb (? );

Ci (c 1, c3c2 ... cm)-the let-off ratio of each comb.

Namely:

For example, it is required that the gram weight of the coat fabric is 180g/m2, the polyester textured yarn with 16.67tex for the back comb is fully penetrated, and the nylon yarn with 2.22tex for the front comb is fully penetrated. Let-off ratio C2= 1.33, transverse density PA= 10 longitudinal/? Longitudinal density PB=2 1.8 rows/? Try to find the length of two comb coils?

In addition to this calculation method, there is a new method to calculate the coil length and let-off ratio:

(A) the empirical calculation method of coil length

In production, people need a simple calculation method of coil length with small error. The following is the empirical calculation method of coil length, which is not only simpler than the theoretical calculation formula usually established according to the coil model, but also accurate and practical.

Now take the warp knitting machine with machine number 28 (E28) as an example. The longitudinal density is 20 rows/? Based on the fabric, the height of each coil is 10? ÷20=0.5? As shown in figure 5-7- 1, and then measure the longitudinal density of 20 rows/by actual measurement? Coil length of various basic tissue structures. As shown in figure 5-7-2.

Figure (1) Plain 2.8? ; Figure (2) Warp-knitted structure 3.4? ; Figure (3) Warp knitting is 4.4? ; Figure (4) Five-needle warp knitting is 4.9? ; Figure (5) Chain knitting is 2.6? ; Figure (6) The length of the warp satin weave is equal to the warp evenness; Figure (7) Specification: The loop length of satin weave is the same as that of velvet weave; Fig. (8) The length of the woven fabric used as hexagonal mesh fabric is equal to the length of the woven fabric; The length of latitude circle in Figure (9) is equal to the number of needles multiplied by the number of needles. Figure (9) is a 4-gauge weft insertion, because the machine number is E28, so the gauge is about 0.9? Four stitches equals 3.6? . The above-mentioned coil length is suitable for the beginning of operation, and it can be 0.2 ~ 0.5 in production as the basis for operation adjustment. Deviation, can be adjusted according to the cloth situation. Because this loop length is only an approximate value as the basis of machine adjustment, the difference between the loop lengths of the open yarn pad and the closed yarn pad is not subdivided, but the lengths of the open yarn pad and the closed yarn pad are roughly the same. With the above basic data, we can easily calculate the coil length at any longitudinal density.