Journal of Textile Research ›› 2024, Vol. 45 ›› Issue (02): 112-118.doi: 10.13475/j.fzxb.20231008501

• Textile Engineering • Previous Articles     Next Articles

Fiber distribution model in pressure bar drafting zone

QIAN Lili1, YU Chongwen1,2()   

  1. 1. College of Textiles, Donghua University, Shanghai 201620, China
    2. Key Laboratory of Textile Science & Technology, Ministry of Education, Donghua University, Shanghai 201620, China
  • Received:2023-10-25 Revised:2023-12-08 Online:2024-02-15 Published:2024-03-29

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Abstract:

Objective Drafting is a key process in spinning and has attracted much attention due to the recent development of virtual spinning technology. The drafting process is essentially a process by which the fibers redistribute and rearrange in sliver or strand. To accurately predict the fiber distribution and better control the fiber movement during drafting, the distribution of fibers in the drafting zone was investigated by analyzing the changes in the weight of fibers along the length direction of sliver or strand.

Method In order to analyze the fiber distribution in the drafting zone theoretically, cutting and weighing method was used to obtain the attenuation curve and the distribution of front-roller and back-roller fibers, from which the distribution of floating fibers, fast-floating fibers, slow-floating fibers, fast-moving fibers, and slow-moving fibers from the theory were expected to be derived. in addition, attenuation curves under different draft parameters were obtained based on the uniform design and a fiber distribution model in the drafting zone.

Results The fiber distribution in the drafting zone with a pressure bar was analyzed and measured. It was shown that in the drafting zone, the distribution of the total fiber, the front-roller fiber, and the back-roller fiber was needed to confirm the distribution of the floating fiber, the fast-floating fiber, the slow-floating fiber, the fast-moving fiber, and the slow-moving fiber. The distribution curves were simplified. For simplicity, man-made fibers of equal length were discussed in this paper. The distribution curves of the front-roller and back-roller fibers in the form of diagonal lines, and the thinning curve could be expressed as a folded line. According to the simplified distribution curves, it was only necessary to determine the attenuation curve.

The experiment was carried out by uniform design, the attenuation curve under different drafting parameters was tested based on the cut-off weighing method, and the regression equation between the turning point of the thinning curve and the drafting parameters such as the drafting multiple, the roller grip distance, the fiber length, the position of the pressure bar was established, and the coefficient of determination R2 was 0.97. The fitting error within the fitted group was 5.66%. The measured results showed that the larger the drafting multiple, the farther away roller-setting, the shorter the fiber length, and the higher the height of the pressure bar, the farther the turning point of the thinning curve was from the back nip. And the position of the pressure bar in the drafting zone did not have a significant effect on the turning point. To verify the accuracy and applicability of the regression equation, polyester and viscose slivers in the drafting zone were cut and weighed respectively, then the tested results were used to identified for comparison with the calculated values, and the average fitting errors were 5.44% and 6.70%. A calculation model of the fiber distribution in the drafting zone was finally derived based on the above analysis and measurement, which can effectively predict the fiber distribution, according to drafting multiples, roller-setting, fiber length, and height of the pressure bar.

Conclusion The accuracy of the model is illustrated by comparing the measured and predicted values, and the model allows the determination of fiber distribution based on drafting parameters, which can effectively predict the fiber distribution, reduce the number of related measurements, and provide a basis for the study of fiber arrangement and movement. The distribution of fibers in the drafting zone is the main factor affecting the evenness of the strip. Mastering the fiber distribution not only predicts the alignment of fibers after drafting but also improves the quality of sliver formation. The fiber distribution equations presented in this study can provide a basis for drafting process simulations and smart textiles.

Key words: pressure bar drafting, attenuation curve, uniform design, drafting process, fitting regression, fiber distribution model, draw frame

CLC Number: 

  • TS101.1

Fig. 1

Diagram of drafting device with upper pressure bar"

Fig. 2

Diagram of fiber distribution in drafting zone"

Fig. 3

Measurement of fiber distribution in drafting zone"

Fig. 4

Simplified curves of fiber distribution during drafting zone"

Tab. 1

Uniform design scheme and test results"

序号 E L/
mm		 l/
mm		 s/
mm		 h/
mm		 X/
mm
1 2.8 66 32 24 4 34.10
2 7.6 68 32 28 6 31.88
3 4.4 68 38 32 6 29.79
4 1.2 62 51 24 2 14.26
5 7.6 60 38 32 2 15.39
6 4.4 66 51 32 2 12.64
7 1.2 68 32 32 2 39.00
8 2.8 68 38 24 2 22.27
9 4.4 64 38 24 4 25.96
10 7.6 66 51 32 4 12.09
11 2.8 60 51 32 4 9.31
12 4.4 60 32 28 4 26.85
13 6.0 66 32 28 2 26.71
14 7.6 62 32 24 4 25.99
15 1.2 60 32 24 6 29.93
16 2.8 64 38 28 2 25.70
17 6.0 62 38 32 6 25.76
18 4.4 64 51 24 6 16.04
19 6.0 68 51 24 4 16.15
20 6.0 60 51 28 6 7.69
21 2.8 62 51 28 6 11.90
22 7.6 64 51 28 2 8.15
23 4.4 62 32 28 2 25.22
24 7.6 66 38 24 6 28.12
25 6.0 60 38 24 2 16.38
26 1.2 66 38 28 6 29.54
27 1.2 68 51 28 4 18.42
28 2.8 64 32 32 6 35.65
29 6.0 64 32 32 4 29.91
30 1.2 62 38 32 4 26.45

Tab. 2

Partial correlation coefficient test table of regression equation"

偏相关系数 t检验值 p值
r(X, x1)=-0.865 0 8.444 4 0.000 1
r(X, x2)=0.462 4 2.555 0 0.017 1
r(X, x3)=-0.978 4 23.172 6 0.000 1
r(X, x 2 2)=-0.442 0 2.414 3 0.023 4
r(X, x1x5)=0.757 3 5.680 5 0.000 1

Tab. 3

Fitting error of fitting group"

序号 观测值/mm 拟合值/mm 拟合误差/%
1 34.10 34.01 0.27
2 31.88 33.47 5.00
3 29.79 29.29 1.67
4 14.26 13.67 4.12
5 15.39 14.03 8.86
6 12.64 12.78 1.14
7 39.00 35.25 9.62
8 22.27 27.46 23.31
9 25.96 25.68 1.06
10 12.09 11.90 1.59
11 9.31 9.66 3.71
12 26.85 25.99 3.21
13 26.71 28.39 6.28
14 25.99 26.22 0.87
15 29.93 29.42 1.69
16 25.70 25.85 0.60
17 25.76 24.78 3.81
18 16.04 15.52 3.22
19 16.15 13.68 15.28
20 7.69 9.50 23.50
21 11.90 14.05 18.05
22 8.15 7.17 11.99
23 25.22 27.10 7.47
24 28.12 27.52 2.14
25 16.38 16.20 1.10
26 29.54 30.39 2.86
27 18.42 18.02 2.19
28 35.65 34.02 4.58
29 29.91 29.85 0.19
30 26.45 26.38 0.26

Tab. 4

Fitting error of polyester fiber test group"

序号 E L/
mm		 l/
mm		 s/
mm		 h/
mm		 观测值/
mm		 拟合值/
mm		 拟合误差/
%
1 3.7 60.0 32 24 4 27.58 25.78 6.53
2 3.7 60.0 51 24 4 9.49 7.99 15.76
3 4.0 65.0 38 24 5 26.01 26.72 2.73
4 5.2 65.0 32 28 4 32.38 30.34 6.29
5 5.2 62.5 38 32 6 25.19 24.86 1.29
6 6.0 62.5 51 28 4 9.61 9.60 0.06
平均误差 5.44

Tab. 5

Fitting error of viscose fiber test group"

序号 E L/
mm		 l/
mm		 s/
mm		 h/
mm		 观测值/
mm		 拟合值/
mm		 拟合误差/
%
1 1.2 62.5 51 24 4 13.65 13.93 2.05
2 3.7 62.5 51 32 6 11.14 13.36 19.96
3 4.0 65.0 38 32 2 22.40 23.98 7.07
4 4.0 65.0 38 24 5 25.31 26.72 5.57
5 5.2 65.0 51 28 3 11.43 11.37 0.51
6 7.0 62.5 38 28 2 18.62 17.68 5.05
平均误差 6.70
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