A method for testing twist of polyester filament yarn

Abstract

The present invention relates to a method for testing the twist of polyester filament yarn. First, a polyester filament yarn to be tested with a certain twist is pre-tensioned at one end and clamped into a fixed clamp, and the other end is clamped into a rotating clamp. Then, the rotating clamp is rotated to remove the twist of the polyester filament yarn. During the removal process, the polyester filament yarn is subjected to friction treatment to generate static electricity on the surface. The constituent units of the polyester filament yarn are dispersed under the action of electrostatic repulsion and are in a mutually parallel state. Finally, the number of rotations of the rotating clamp is recorded to obtain the twist of the polyester filament yarn. The method for testing the twist of polyester filament yarn of the present invention can conveniently and quickly detect the twist of polyester filament yarn, and is particularly suitable for polyester filament yarn with thinner monofilaments. It is not necessary to use an amplifying device to observe whether the twist is completely removed, thereby improving the accuracy of the test.

Description

Technical Field

[0001] The invention belongs to the technical field of yarn twist testing and relates to a method for testing the twist of polyester filament yarn. Background Art

[0002] After twisting, polyester filaments are formed into yarns. At this time, the yarns have certain physical and mechanical properties such as strength, elasticity, elongation, gloss, and feel, which are more conducive to weaving, and can make the fabrics have certain strength, different styles, and specific wearing properties. Using twist test methods to accurately test yarn twist, achieve reasonable twist design, and reduce the discreteness of twist distribution is an important basis for ensuring the overall quality of textiles.

[0003] At present, twist testing is mainly divided into direct counting method and untwisting and twisting method. The direct counting method is to remove the twist of the yarn under a specified tension, so that the yarn forms parallel units, and the twist of the yarn is obtained according to the number of turns required for the yarn to remove the twist. It is currently the benchmark for twist testing. This method is technically difficult and mainly relies on the operator's experience. Polyester filaments, especially fine denier polyester filament monofilaments, are very thin, resulting in the inability to confirm the parallel units formed by the fibers in the twist test, resulting in the inability to complete direct counting.

[0004] Reference 1 (A Brief Discussion on the Problems and Revision Prospects of Yarn Twist Test Methods [J]. China Fiber Inspection, 2024, (02): 73-77.) By using a magnifying glass and an analysis needle, the yarn is untwisted according to the inclination direction of the fibers in the yarn to confirm the parallel units. However, this method uses a magnifying glass, has certain requirements for the light in the test environment, is complex to operate, and has low efficiency, so it cannot be applied to the needs of large-scale testing and inspection in factories.

[0005] Reference 2 (Discussion on the image-based test method for the twist of jet vortex spinning yarn [J]. Journal of Textile Research, 2021, 42(02): 60-64.) The yarn appearance is photographed by scanning electron microscope, and then the twist angle of the yarn is measured by Photoshop image processing software. The twist coefficient is then calculated by the formula, and then the twist is calculated. This method uses an electron microscope, and the testing cost is high. If the yarn has a lot of hairiness and uneven yarn, the clarity of the image and the accuracy of the measurement cannot be guaranteed.

[0006] The untwisting and re-twisting method is to untwist the yarn and re-twist it in the opposite direction until the sample reaches the initial length. Assuming that the number of twists of the re-twisting is equal to the original twist of the sample, half of the number of twists recorded on the counter represents the number of twists of the sample. However, this method is significantly affected by the pre-tension, and improper selection of the pre-tension will lead to large errors in the test.

[0007] Therefore, it is of great significance to study a method for testing the twist of polyester filament yarn to solve the problems existing in the prior art. Summary of the invention

[0008] The purpose of the invention is to solve the problems existing in the prior art and provide a method for testing the twist of polyester filament yarn.

[0009] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0010] A method for testing the twist of a polyester filament yarn comprises the following steps: firstly, pre-tensioning one end of a polyester filament yarn to be tested and clamping it into a fixed clamp, and clamping the other end into a rotating clamp, rotating the rotating clamp to remove the twist of the polyester filament yarn, and performing friction treatment on the polyester filament yarn during the untwisting process to generate static electricity on the surface. On the one hand, the static electricity generates to make the yarn fluffy, and on the other hand, the yarn twist moves, so as to facilitate observation of whether the residual twist is completely removed. The constituent units of the polyester filament yarn are dispersed under the action of electrostatic repulsion and are parallel to each other (the so-called parallel state is not strictly mathematical parallelism, but the two ends are fixed, and multiple monofilaments or yarns between two network points are in an arc-shaped fluffy state. During the untwisting process, the twist moves with the friction of the object and will not stay at the network point or a fixed position. As the untwisting is gradually carried out, the static electricity generated on the fiber surface makes the yarn bundle more fluffy, so it is easy to observe the twist removal), and finally the number of rotations of the rotating clamp is recorded to obtain the twist of the polyester filament yarn.

[0011] As the preferred technical solution:

[0012] In the above-mentioned method for testing twist of polyester filament yarn, the pre-tension and test length of the test sample are determined according to GB / T 14345-2008 standard.

[0013] In the above-mentioned method for testing twist of polyester filament yarn, the article subjected to friction treatment on the polyester filament yarn is an article having a different dielectric constant from that of the polyester filament yarn.

[0014] In the method for testing the twist of polyester filament yarn as described above, preferably, the object used for friction treatment of the polyester filament yarn is teaching chalk or solid limestone, more preferably teaching chalk, because the friction between the teaching chalk and the yarn will produce fine powder attached to the surface of the yarn, making it easier for the human eye to observe the residual twist.

[0015] A polyester filament yarn twist test method as described above, friction is performed along the length direction of the polyester filament yarn, the friction distance (i.e., the distance that the object used for friction passes in the direction of the force) is equal to the length of the polyester filament yarn (excluding the two ends clamped in the fixed clamp and the rotating clamp), the friction force is 0.1~20N, a certain friction force needs to be generated between the polyester filament yarn and the teaching chalk to facilitate the generation of static electricity, but it cannot be too large to prevent the polyester filament yarn from being worn off, which is not conducive to the measurement of twist; the specific friction force can be adjusted according to the linear density and breaking strength of the polyester filament yarn to ensure that the polyester filament yarn is not broken after being subjected to force; the friction speed is 0.1~0.8m / s.

[0016] Beneficial effects:

[0017] The polyester filament yarn twist testing method of the present invention can conveniently and quickly detect the twist of the polyester filament yarn, and is particularly suitable for polyester filament yarns with thinner monofilaments. It can observe whether the twist is completely removed without the aid of an amplifying device, thereby improving the accuracy of the test. DETAILED DESCRIPTION

[0018] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0019] A method for testing the twist of polyester filament yarn, the specific process is as follows:

[0020] First, a polyester filament yarn with a certain twist is pre-tensioned at one end and then clamped into a fixed clamp, and the other end is clamped into a rotating clamp. The rotating clamp is rotated to remove the twist of the polyester filament yarn. During the removal process, the polyester filament yarn is rubbed with an object with a different dielectric constant from the polyester filament yarn (such as teaching chalk, solid limestone) to generate static electricity on the surface. The constituent units of the polyester filament yarn are dispersed under the action of electrostatic repulsion and are parallel to each other. Finally, the number of rotations of the rotating clamp is recorded to obtain the twist of the polyester filament yarn. Among them, the pre-tension and test length of the test sample are determined according to GB / T 14345-2008 standard, the friction force is 0.1~20N, and the friction speed is 0.1~0.8m / s.

[0021] The following is a specific example of a method for testing the twist of polyester filament yarn according to the present invention, which is as follows:

[0022] Example 1

[0023] First, a polyester filament yarn to be tested with a length of 300 mm and a specification of 1100 dtex / 192f (the twist control range of the polyester filament yarn during preparation is 92 twists / m~108 twists / m) is pre-applied with a tension of 0.05 cN / dtex at one end and then clamped into a fixed clamp, and the other end is clamped into a rotating clamp. The rotating clamp is rotated to remove the twist of the polyester filament yarn. During the removal process, the polyester filament yarn is rubbed with a teaching chalk, wherein the friction force is 6N and the friction speed is 0.4m / s. After the friction treatment generates static electricity on the surface, the constituent units of the polyester filament yarn are dispersed under the action of electrostatic repulsion and are parallel to each other. Finally, the number of rotations of the rotating clamp is recorded as 30, and the twist of the polyester filament yarn is obtained, i.e., 100 twists / m.

[0024] Example 2

[0025] First, a polyester filament yarn to be tested with a length of 300 mm and a specification of 550 dtex / 96f (the twist control range of the polyester filament yarn during preparation is 184 twists / m~216 twists / m) is pre-applied with a tension of 0.05 cN / dtex at one end and then clamped into a fixed clamp, and the other end is clamped into a rotating clamp. The rotating clamp is rotated to remove the twist of the polyester filament yarn. During the removal process, the polyester filament yarn is rubbed with solid limestone, wherein the friction force is 4 N and the friction speed is 0.5 m / s. After the friction treatment generates static electricity on the surface, the constituent units of the polyester filament yarn are dispersed under the action of electrostatic repulsion and are parallel to each other. Finally, the number of rotations of the rotating clamp is recorded as 60.6, and the twist of the polyester filament yarn is obtained, i.e., 202 twists / m.

[0026] Example 3

[0027] First, a polyester filament yarn to be tested with a length of 300 mm and a specification of 3300 dtex / 384f (the twist control range of the polyester filament yarn during preparation is 55 twists / m~65 twists / m) is pre-applied with a tension of 0.05 cN / dtex at one end and then clamped into a fixed clamp, and the other end is clamped into a rotating clamp. The rotating clamp is rotated to remove the twist of the polyester filament yarn. During the removal process, the polyester filament yarn is rubbed with a plastic made of PP material, wherein the friction force is 10 N and the friction speed is 0.3 m / s. After the friction treatment generates static electricity on the surface, the constituent units of the polyester filament yarn are dispersed under the action of electrostatic repulsion and are parallel to each other. Finally, the number of rotations of the rotating clamp is recorded as 18, and the twist of the polyester filament yarn is obtained, that is, 60 twists / m.

Claims

1. A method for testing the twist of polyester filament yarn, characterized in that: First, one end of a polyester filament yarn to be tested with a certain twist is pre-tensioned and clamped into a fixed clamp, and the other end is clamped into a rotating clamp, and then the rotating clamp is rotated to remove the twist of the polyester filament yarn. During the removal process, the polyester filament yarn is rubbed to generate static electricity on the surface. The constituent units of the polyester filament yarn are dispersed under the action of electrostatic repulsion and are parallel to each other. Finally, the number of rotations of the rotating clamp is recorded to obtain the twist of the polyester filament yarn. The article to which the polyester filament yarn is subjected to friction treatment is an article having a different dielectric constant from that of the polyester filament yarn; The polyester filament yarn is rubbed along its length direction, and the friction distance is equal to the length of the polyester filament yarn; the friction distance is the distance that the object used for friction passes in the direction of the force, and the length of the polyester filament yarn does not include the two end positions clamped in the fixed clamp and the rotating clamp; the friction force is 0.1-20N, and the friction speed is 0.1-0.8m / s.

2. A method for testing twist of polyester filament yarn according to claim 1, characterized in that: The pre-tension and length of the test specimen are determined in accordance with GB / T 14345-2008.

3. A method for testing twist of polyester filament yarn according to claim 1, characterized in that: The article with which the polyester filament yarn is rubbed is teaching chalk or solid limestone.