Establishing method of applicable standard of woven filter cloth for dry spinning

Abstract

The invention relates to a method for establishing an applicable standard of woven filter cloth for dry spinning, which comprises the following steps: testing the breaking strength, breaking elongation and air permeability of the filter cloth, establishing a quantitative evaluation function Y = 0.5 Pstd + 0.3 Estd + 0.2 Sstd based on the weight priority of air permeability, breaking elongation and strength, and judging that the filter cloth is applicable when Y is greater than or equal to 0.4; the method has the advantages that a quantitative evaluation standard is established by testing the breaking strength, the breaking elongation and the air permeability of the fabric aiming at the defects of a traditional on-machine cap wiping experiment, the detection period is shortened, the detection accuracy is improved, the detection efficiency of the filter material is effectively improved, and meanwhile, accurate reference is provided for weaving of woven filter cloth; the problems of complex operation, long time consumption and high error rate of a traditional method are solved.

Description

Technical Field

[0001] This invention relates to the field of dry spinning technology, and in particular to a method for establishing applicable standards for woven filter cloths used in dry spinning. Background Technology

[0002] In the dry spinning process, the spinning solution needs to be extruded through a spinneret to form fine filaments. The woven filter cloth inside the spinneret is a key filtration material, and its main functions include: filtering impurities in the spinning solution, dispersing the flow rate of the spinning solution, and ensuring a uniform distribution of pressure inside the spinneret (usually 2MPa to 6MPa). The filter cloth undergoes significant deformation under spinning pressure, and its deformation state directly affects the pore size and distribution uniformity, thus determining the stability of the sizing output—too large a pore size leads to filament bundling, while too small a pore size leads to sizing dripping, ultimately affecting the spinning quality.

[0003] Currently, the traditional method used in the industry to determine the suitability of filter cloths is the "on-machine cap wiping test": the filter cloth is installed on the spinneret and put into actual production. The state of the fiber bundles during the spinning process is observed (such as whether there are defects such as slanted fibers, dripping, or bundled fibers). The "number of successful cap wipings / total number of cap wipings" is counted as the cap wiping rate. When the cap wiping rate is ≥40%, the filter cloth is considered qualified; otherwise, it is unqualified. This method has long been the sole standard for testing the suitability of filter cloths, relying on production practice to verify the performance of the filter cloths.

[0004] Although the traditional on-machine cap wiping test can directly reflect the actual performance of the filter cloth, it has the following inherent drawbacks:

[0005] 1. Complex operation and high resource consumption

[0006] It requires the use of actual production equipment (spinning machines, spinnerets, etc.), interrupting the normal production process; the testing process requires dedicated personnel to continuously observe the state of the filament bundle, investing a lot of manpower, material resources and time costs, making it difficult to meet the needs of rapid testing in large-scale production.

[0007] 2. Long testing cycle and low efficiency.

[0008] The entire process of "filter cloth installation → spinning operation → fiber bundle observation → data statistics" needs to be completed, and the single inspection cycle can take several days (depending on the production batch size). This makes it impossible to achieve rapid screening of filter cloth before it enters the warehouse, which can easily lead to unqualified filter cloth flowing into the production process.

[0009] 3. The correlation between filter cloth performance and spinning quality is unclear, leading to a lack of direction for improvement.

[0010] Traditional methods only provide qualitative feedback on filter cloth suitability through "qualified / unqualified" results, failing to establish a quantitative relationship between core performance indicators of filter cloth (such as mechanical properties and air permeability) and spinning quality (such as pore size uniformity and sizing yield). When filter cloth is unqualified, it is impossible to pinpoint key defects (such as insufficient air permeability or insufficient strength), and the only solution is to adjust the process through trial and error (such as blindly changing yarns or adjusting weaving methods), resulting in low efficiency and high costs.

[0011] Therefore, in summary, there is an urgent need for an efficient, accurate, and quantifiable method for evaluating the suitability of filter cloths to replace the traditional on-machine cap wiping test, thereby enabling rapid detection and optimization of filter cloth quality. Summary of the Invention

[0012] The purpose of this invention is to solve the above-mentioned problems existing in the prior art and to provide a method for establishing applicable standards for dry spinning woven filter cloth.

[0013] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0014] A method for establishing applicable standards for woven filter cloths used in dry spinning includes the following steps:

[0015] S1. Obtain the woven filter cloth sample to be tested;

[0016] S2. According to the national standard GB / T 3923.1-2013 "Tension properties of fabrics - Part 1: Determination of breaking strength and elongation at break", test the warp breaking strength, weft breaking strength, warp breaking elongation and weft breaking elongation of the sample.

[0017] S3. Test the air permeability of the sample according to the national standard GB / T 5453-1997 "Determination of air permeability of textile fabrics";

[0018] S4. Based on the weighting priority of air permeability > elongation at break > breaking strength, establish a quantitative evaluation function relationship:

[0019] Y = 0.5Pstd + 0.3Estd + 0.2Sstd

[0020] Where Y is the accuracy of the predicted filter cloth wiping cap, with a value range of [0,1], corresponding to 0%-100%; Pstd is the normalized value of air permeability, Estd is the normalized value of elongation at break, and Sstd is the normalized value of tensile strength; the relationship is used to correlate the deformation state and spinning quality of the filter cloth under spinning pressure of 2MPa-6MPa.

[0021] S5. The suitability of the filter cloth is determined by calculating the result Y of the quantitative evaluation function: when Y≥0.4, the filter cloth is deemed suitable; when the air permeability is not up to standard, even if other indicators are qualified, the Y value is still <0.4, and the filter cloth is deemed unsuitable.

[0022] Preferably, the weighting coefficients include: air permeability 0.5, elongation at break 0.3, and tensile strength 0.2. The weighting coefficients are determined by multiple linear regression analysis, specifically: based on the performance test data and on-machine wiping experiment data of multiple sets of filter cloths with different structures, the actual wiping rate is used as the dependent variable, and the standardized values ​​of air permeability, elongation at break, and tensile strength are used as independent variables, and the least squares method is used for fitting.

[0023] Preferably, the standardized air permeability value Pstd is calculated as follows:

[0024] When the measured air permeability value P < 1, Pstd = 0;

[0025] When 1≤P≤3.5, Pstd=(P-1) / (3.5-1);

[0026] When P > 3.5, Pstd = 1;

[0027] Where P is the measured air permeability value, in mL / s·cm. 2 1-3.5 mL / s·cm 2 A preset standard range for breathability is provided.

[0028] Preferably, the standardized value of elongation at break, Estd, is calculated as follows:

[0029]

[0030] Wherein, E_warp is the measured value of elongation at break in the warp direction, and E_weft is the measured value of elongation at break in the latitudinal direction; the preset standard range for elongation at break in the warp direction is 30% to 40%, and the preset standard range for elongation at break in the latitudinal direction is 32% to 42%.

[0031] Preferably, the normalized fracture strength value Sstd is calculated as follows:

[0032]

[0033] Wherein, S_longitude is the measured value of the longitudinal fracture strength, and S_latitude is the measured value of the latitudinal fracture strength; the preset standard value of the longitudinal fracture strength is >1000N, and the preset standard value of the latitudinal fracture strength is >520N.

[0034] Preferably, in step 5, when the filter cloth is determined to be unsuitable, the filter cloth performance can be adjusted through the following targeted improvement measures:

[0035] If the breathability is not up to standard, reduce the warp or weft density to reduce the fabric tightness, or reduce the calendering temperature to reduce fiber adhesion.

[0036] If the strength is insufficient, replace with high-strength yarn or increase the warp density;

[0037] If the elongation is abnormal, adjust the yarn twist or weaving process parameters.

[0038] Preferably, the preset standard value of the breaking strength is determined based on a stress simulation experiment under a spinning pressure of 2MPa to 6MPa, which is used to ensure that the filter cloth does not break when resisting the maximum deformation; the preset standard range of breaking elongation and air permeability is verified by deformation-pore size correlation experiment, which is used to ensure the uniformity of pore size after the filter cloth is deformed.

[0039] Due to the adoption of the above technical solution, the beneficial effects obtained by the present invention include:

[0040] This invention replaces traditional machine experiments with laboratory testing, uses quantitative models to correlate spinning quality, and employs targeted measures to guide optimization. It effectively solves the problems of complex operation, long time consumption, and high error in traditional methods, and achieves high efficiency, accuracy, and standardization in the quality evaluation of woven filter cloths for dry spinning. At the same time, it provides a scientific basis for the optimization of filter cloth weaving process and significantly improves the detection efficiency and application reliability of filter materials. Attached Figure Description

[0041] Figure 1 This is a flowchart illustrating an embodiment of the method for establishing applicable standards for dry-spun woven filter cloths according to the present invention.

[0042] Figure 2 This is a cross-sectional view of the woven filter cloth in the deformation state during an application of an embodiment of the present invention.

[0043] Figure 3 This is a cross-sectional view of the fabric deformation profile curve according to an embodiment of the present invention.

[0044] Figure 4 This is a cross-sectional view of the actual deformation profile of the filter cloth after it is removed from the machine according to an embodiment of the present invention.

[0045] Figure 5 This is a photograph of a plain weave filter cloth according to an embodiment of the present invention.

[0046] Figure 6 This is a photograph of a woven filter cloth with a twill weave, according to an embodiment of the present invention. Detailed Implementation

[0047] See Figure 1-6As shown, this invention mainly establishes a method for establishing applicable standards for dry-spun woven filter cloths based on tests of breaking strength, breaking elongation, and air permeability. By replacing on-machine experiments with laboratory testing, only three core indicators of the fabric—breaking strength, breaking elongation, and air permeability—need to be tested to complete the filter cloth applicability evaluation and preliminarily determine whether the woven filter cloth can meet the usage requirements. Moreover, the entire testing process is simple, convenient, and has a short testing cycle, greatly simplifying the filter cloth qualification testing process and effectively improving the filter cloth testing efficiency.

[0048] Based on this, the present invention specifically provides a method for establishing applicable standards for woven filter cloths used in dry spinning, the method comprising:

[0049] S1. Obtain the woven filter cloth sample to be tested;

[0050] Select woven filter cloths with different weave structures such as plain weave and broken twill weave (e.g., nylon 66 filter cloth).

[0051] S2. According to the national standard GB / T 3923.1-2013 "Tension properties of fabrics - Part 1: Determination of breaking strength and elongation at break", test the warp breaking strength, weft breaking strength, warp breaking elongation and weft breaking elongation of the sample.

[0052] S3. Test the air permeability of the sample according to the national standard GB / T 5453-1997 "Determination of air permeability of textile fabrics";

[0053] S4. Based on the weighting priority of air permeability > elongation at break > breaking strength, establish a quantitative evaluation function relationship:

[0054] Y = 0.5Pstd + 0.3Estd + 0.2Sstd

[0055] Where Y is the accuracy of the predicted filter cloth wiping, with a value range of [0,1], corresponding to 0%-100%; Pstd is the normalized value of air permeability, Estd is the normalized value of elongation at break, and Sstd is the normalized value of tensile strength; the relationship is used to correlate the deformation state and spinning quality of the filter cloth under spinning pressure of 2MPa-6MPa.

[0056] S5. The suitability of the filter cloth is determined by calculating the result Y of the quantitative evaluation function: when Y≥0.4, the filter cloth is deemed suitable; when the air permeability is not up to standard, even if other indicators are qualified, the Y value is still <0.4, and the filter cloth is deemed unsuitable.

[0057] In this embodiment, the weighting coefficients include: air permeability 0.5, elongation at break 0.3, and tensile strength 0.2. The weighting coefficients are determined by multiple linear regression analysis, specifically: based on the performance test data of multiple sets of filter cloths with different structures and the machine wiping experiment data, the actual wiping rate is the dependent variable, and the standardized values ​​of air permeability, elongation at break, and tensile strength are the independent variables, and the least squares method is used to fit the data.

[0058] The quantitative evaluation function relationship Y = 0.5Pstd + 0.3Estd + 0.2Sstd is established based on the following experimental data and mechanism analysis:

[0059] Analysis of the influencing mechanism of the index: Air permeability: directly reflects the initial pore size of the filter cloth and is linearly related to the pulp output. Too large a pore size leads to yarn breakage, while too small a pore size leads to pulp dripping. It plays a decisive role in the spinning quality and therefore has the highest weight.

[0060] Elongation at break: This determines the degree of deformation of the filter cloth under spinning pressure. Abnormal deformation will lead to uneven pore size distribution, which indirectly affects the stability of air permeability, although the degree of influence is secondary.

[0061] Tensile strength: Ensures that the filter cloth does not break under pressure. It is a basic performance guarantee, but it does not directly determine the filtration effect and has the lowest weight.

[0062] In addition, performance tests and on-machine wiping experiments were conducted on multiple groups of filter cloths with different structures (including plain weave and twill weave) (see data in Example 1). Multiple linear regression analysis was used, with the actual wiping rate as the dependent variable and the standardized values ​​of air permeability, elongation at break, and tensile strength as independent variables. Weighting coefficients were obtained by fitting the data using the least squares method. The regression analysis results showed that the regression coefficient for the standardized value of air permeability was 0.52 (P<0.01), the regression coefficient for the standardized value of elongation at break was 0.29 (P<0.05), and the regression coefficient for the standardized value of tensile strength was 0.19 (P<0.05), which highly matched the weights of 0.5, 0.3, and 0.2 set in this invention.

[0063] In this embodiment, the normalized air permeability value Pstd is calculated as follows:

[0064] When the measured air permeability value P < 1, Pstd = 0;

[0065] When 1≤P≤3.5, Pstd=(P-1) / (3.5-1);

[0066] When P > 3.5, Pstd = 1;

[0067] Where P is the measured air permeability value, in mL / s·cm. 2 1-3.5 mL / s·cm 2 A preset standard range for breathability is provided.

[0068] In this embodiment, the standardized value of elongation at break, Estd, is calculated as follows:

[0069]

[0070] Wherein, Ewarp is the measured value of warp breaking elongation, and Eweft is the measured value of weft breaking elongation; the preset standard range for warp breaking elongation is 30%–40%, and the preset standard range for weft breaking elongation is 32%–42%; the fabric air permeability is 1–3.5 mL / s × cm2. This range is verified through deformation-pore size correlation experiments, which can ensure the uniformity of pore size after deformation of the filter cloth.

[0071] In this embodiment, the normalized fracture strength value Sstd is calculated as follows:

[0072]

[0073] Wherein, S_warp is the measured value of warp breaking strength, and S_weft is the measured value of weft breaking strength; the preset standard value of warp breaking strength is >1000N, and the preset standard value of weft breaking strength is >520N; these values ​​are determined based on stress simulation experiments under spinning pressure of 2MPa to 6MPa, which can ensure that the filter cloth does not break when resisting the maximum deformation.

[0074] In this embodiment, when the filter cloth is determined to be unsuitable, the filter cloth performance can be adjusted through the following targeted improvement measures:

[0075] If the breathability is not up to standard, reduce the warp or weft density to reduce the fabric tightness, or reduce the calendering temperature to reduce fiber adhesion.

[0076] If the strength is insufficient, replace with high-strength yarn or increase the warp density;

[0077] If the elongation is abnormal, adjust the yarn twist or weaving process parameters.

[0078] In this embodiment, the method is used to replace the traditional machine-based cap-wiping experiment. By testing the breaking strength, elongation at break, and air permeability in the laboratory, it solves the problems of complex operation, long time consumption, and high error rate of the traditional method.

[0079] In this embodiment, the preset standard value of breaking strength is determined based on the stress simulation experiment under spinning pressure of 2MPa to 6MPa, which is used to ensure that the filter cloth does not break when resisting the maximum deformation; the preset standard range of breaking elongation and air permeability is verified by deformation-pore size correlation experiment, which is used to ensure the uniformity of pore size after the filter cloth is deformed.

[0080] To further illustrate the technical features of this solution, the following experimental data is used to explain the above content:

[0081] The operation steps in the following embodiments are the specific steps of the testing and evaluation method of the present invention. Whether the results of the evaluation of the breaking strength, breaking elongation and air permeability of the sample under test in each embodiment are consistent with the results of the wiping cap test prove the rationality of the woven filter cloth testing and evaluation method of the present invention.

[0082] Figure 5 This illustrates a plain weave fabric, which is made of warp and weft yarns interwoven in alternating layers. Figure 6 The illustration shows a 3 / 1 broken twill fabric, which consists of left and right twills, forming a discontinuous twill line structure at the junction.

[0083] Table 1 shows the experimental data for the actual sample performance test.

[0084]

[0085]

[0086] The air permeability of the fabric was tested using a YG461E-Ⅲ fully automatic air permeability meter under the following conditions: pressure 100 Pa, test area 20 cm², and pore size Φ0.8 mm. The sample was clamped on a sample platform, ensuring it remained flat and undeformed. Tests were performed on different parts of the same sample, with 10 tests conducted. The specific experimental results are recorded in Table 2 below.

[0087] Example 2

[0088] Selection of the fabric to be tested: Plain weave fabric was selected as the fabric to be tested.

[0089] Using the same testing method as in Example 1, the experimental results are shown in Table 2 below.

[0090] Example 3

[0091] Selection of the fabric to be tested: Broken twill fabric was selected as the fabric to be tested.

[0092] Using the same testing method as in Example 1, the experimental results are shown in Table 2 below.

[0093] Example 4

[0094] Selection of the fabric to be tested: Plain weave fabric was selected as the fabric to be tested.

[0095] Using the same testing method as in Example 1, the experimental results are shown in Table 2 below.

[0096] Example 5

[0097] Selection of the fabric to be tested: Plain weave fabric was selected as the fabric to be tested.

[0098] Using the same testing method as in Example 1, the experimental results are shown in Table 2 below.

[0099] Table 2: Experimental data of performance tests for the embodiments

[0100]

[0101]

[0102] Final result: The judgment criteria are consistent with the results of wiping the cap.

[0103] It should be noted that this invention relates the mechanical properties and air permeability of the fabric to the actual form of the woven filter cloth in application. The strength requirement ensures that the fabric will not break or be damaged during use. Elongation and air permeability are important indicators that affect the final pore size of the fabric after being stressed. The laboratory test (breaking strength, breaking elongation, air permeability) replaces the machine test, which greatly improves the testing efficiency and accuracy. Its operation is simplified and does not require production equipment. Only conventional laboratory instruments (such as fabric strength tester and air permeability meter) are needed to complete the test, reducing the dependence on manpower and material resources.

[0104] Simultaneously, based on multiple linear regression analysis, the weight priority of "air permeability (0.5) > elongation at break (0.3) > strength (0.2)" was determined, which is consistent with the actual mechanism of influence on spinning quality (air permeability directly determines the amount of sizing, elongation affects the uniformity of pore size after deformation, and strength ensures that the filter cloth does not break); and verified through examples (such as Y=0.48 in Example 3, Y=0.48 corresponds to a 50% wiping rate, and Y=0.51 in Example 4, Y=0.51 corresponds to a 54% wiping rate), the deviation between the function calculation results and the actual machine effect is <5%, realizing accurate prediction of spinning quality;

[0105] In addition, for substandard filter cloths, defects can be directly located and improvement plans can be proposed based on the test results, such as:

[0106] If the breathability is not up to standard: reduce the warp / weft density (reduce fabric tightness) or reduce the calendering temperature (reduce fiber adhesion);

[0107] Insufficient strength: Replace with high-strength yarn or increase warp density;

[0108] Abnormal elongation: Adjust yarn twist or weaving process parameters;

[0109] Furthermore, the above measures have been verified through the "deformation-pore size correlation experiment" in the document, which can specifically improve the performance of the filter cloth and optimize efficiency.

[0110] The foregoing descriptions and embodiments are provided to enable those skilled in the art to understand and apply the present invention. It will be apparent to those skilled in the art that various modifications can be easily made to these contents, and the general principles described herein can be applied to other embodiments without creative effort. Therefore, the present invention is not limited to the foregoing descriptions and embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from its scope should be within the protection scope of the present invention.

Claims

1. A method for establishing applicable standards for woven filter cloths used in dry spinning, characterized in that, Includes the following steps: S1. Obtain the woven filter cloth sample to be tested; S2. According to the national standard GB / T 3923.1-2013 "Tension properties of fabrics - Part 1: Determination of breaking strength and elongation at break", test the warp breaking strength, weft breaking strength, warp breaking elongation and weft breaking elongation of the sample. S3. Test the air permeability of the sample according to the national standard GB / T 5453-1997 "Textiles - Determination of air permeability of fabrics"; S4. Based on the weighting priority of air permeability > elongation at break > breaking strength, establish a quantitative evaluation function relationship: Y = 0.5Pstd + 0.3Estd + 0.2Sstd Where Y is the accuracy of the predicted filter cloth wiping cap, with a value range of [0,1], corresponding to 0%-100%; Pstd is the normalized value of air permeability, Estd is the normalized value of elongation at break, and Sstd is the normalized value of tensile strength; the relationship is used to correlate the deformation state and spinning quality of the filter cloth under spinning pressure of 2MPa-6MPa. S5. The suitability of the filter cloth is determined by calculating the result Y of the quantitative evaluation function: when Y≥0.4, the filter cloth is deemed suitable; when the air permeability is not up to standard, even if other indicators are qualified, the Y value is still <0.4, and the filter cloth is deemed unsuitable.

2. The method according to claim 1, characterized in that, The weighting coefficients include: air permeability 0.5, elongation at break 0.3, and tensile strength 0.

2. The weighting coefficients are determined by multiple linear regression analysis, specifically: based on the performance test data and on-machine wiping experiment data of multiple sets of filter cloths with different structures, the actual wiping rate is the dependent variable, and the standardized values ​​of air permeability, elongation at break, and tensile strength are the independent variables, and the least squares method is used for fitting.

3. The method according to claim 1, characterized in that, The standardized air permeability value Pstd is calculated as follows: When the measured air permeability value P < 1, Pstd = 0; When 1≤P≤3.5, Pstd=(P-1) / (3.5-1); When P > 3.5, Pstd = 1; Where P is the measured air permeability value, in mL / s·cm. 2 1-3.5 mL / s·cm 2 The standard range for breathability is preset.

4. The method according to claim 1, characterized in that, The standardized value of elongation at break, Estd, is calculated as follows: Wherein, E_warp is the measured value of elongation at break in the warp direction, and E_weft is the measured value of elongation at break in the latitudinal direction; the preset standard range for elongation at break in the warp direction is 30% to 40%, and the preset standard range for elongation at break in the latitudinal direction is 32% to 42%.

5. The method according to claim 1, characterized in that, The normalized value of fracture strength Sstd is calculated as follows: Wherein, S_longitude is the measured value of the longitudinal fracture strength, and S_latitude is the measured value of the latitudinal fracture strength; the preset standard value of the longitudinal fracture strength is >1000N, and the preset standard value of the latitudinal fracture strength is >520N.

6. The method according to claim 1, characterized in that, In step 5, when the filter cloth is determined to be unsuitable, the filter cloth performance can be adjusted through the following targeted improvement measures: If the breathability is not up to standard, reduce the warp or weft density to reduce the fabric tightness, or reduce the calendering temperature to reduce fiber adhesion. If the strength is insufficient, replace with high-strength yarn or increase the warp density; If the elongation is abnormal, adjust the yarn twist or weaving process parameters.

7. The method according to claim 1, characterized in that, The preset standard value of the breaking strength is determined based on the stress simulation experiment under the spinning pressure of 2MPa to 6MPa, which is used to ensure that the filter cloth does not break when resisting the maximum deformation; the preset standard range of breaking elongation and air permeability is verified by the deformation-pore size correlation experiment, which is used to ensure the uniformity of pore size after the filter cloth is deformed.

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