RU2526112C2 - Method of determining fixedness of loop in structure of knitted fabric - Google Patents

Abstract

FIELD: textiles, paper.

SUBSTANCE: invention relates to textile materials science, and is intended for an objective assessment of properties of knitted fabrics for garments in textile and consumer goods industry. The method consists in that a sample from the test knitted fabric is subjected to testing by extracting one loop from the knitted fabric structure according to the preliminary calculated length of thread in the loop followed by calculation of the force required to extract the unit of the length of the thread in a loop, according to the formula:

, where f_n is fixedness of loop in the structure of knitted fabric, mN/mm; F_n is the force required to extract the loop from the knitted fabric, mN; l_n is the length of the thread in a loop, mm.

EFFECT: increase in objectivity and reliability of determination is achieved.

2 tbl, 3 dwg

Description

The invention relates to textile materials science and is intended for an objective assessment of the properties of knitted fabrics for clothes in the textile and light industries, and can also be used for standardization, during research, periodic and certification tests.

An object of the invention is to develop a method for evaluating the proposed new indicator of the quality of knitted fabrics - loop fastening in the structure of a knitted fabric. The proposed indicator can serve as an indirect criterion for assessing the stability of the structure of a knitted fabric.

Closest to the proposed method are methods for assessing tissue resistance to displacement of threads [1]. The ability of filaments to shift in the structure of the fabric is manifested in the form of the following properties: the extension of the filaments in the fabric [2] and crumbling [3, 4]. Shedding and expandability of the threads characterize the degree of fixation of one system of threads in the fabric relative to another. The first of these properties is usually manifested in the process of making clothes from them, when there is a loss of threads along the trimmed edge. The second property is observed in tissues during operation, when the material experiences significant local stresses. The resistance of the fabric to crumbling (for cotton fabrics) is determined by the amount of force required to drop the two-millimeter layer of one system of threads relative to another. The resistance of the fabric to expandability is determined by the magnitude of the force required to fire one system of threads relative to another.

Of the two properties discussed above, the expandability of the threads is essentially closer to the proposed new indicator for assessing the stability of the structure of a knitted fabric - the fastening of the loop in the structure of a knitted fabric. With insufficient loop fastening in the structure of the knitted fabric, the appearance of the fabric will deteriorate, the service life will decrease due to distortion of the shape of the loops and an increase in the gap between the threads.

The technical result of the invention is to obtain reliable and objective information that determines the tightness of the loop in the structure of a knitted fabric. The characteristics obtained during testing make it possible to evaluate the resistance of knitted fabric elements to disruption of the loop structure and to predict the stability of the structure of knitted fabrics during operation.

The ability to predict the stability of the structure of knitted fabrics will allow us to design rational structures of knitted fabrics that are resistant to operational loads.

The specified technical result is achieved due to the development of a method for assessing the fastening of a loop in the structure of a knitted fabric. It is proposed to use the force necessary to extract a unit of length of thread in the loop (1 mm) from the knitted fabric as a criterion for the loop to be fixed in the structure of the knitted fabric. The method consists in the fact that the sample from the test knitted fabric is subjected to tests by removing one loop from the structure of the knitted fabric (figure 1). The length of the thread in the loop is preliminarily calculated, the value of which the loop is removed from the structure of the knitted fabric.

The length of the thread in the loop is determined by the calculation method according to the formulas of A.S. Dalidovich [5] or the standard method [6]. When using the standard method, the dissolution of the elementary sample is carried out. On an elementary sample, for example, for paintings of main culinary weaves 10 cm long, 100 loop stitches are counted (for single paintings) and an incision is made; then five rows are dissolved and each thread is measured in a straightened state. In fabrics of smooth culinary weaves with a homogeneous loop structure, the average length of the thread in the loop is determined as the arithmetic mean of all measurements of the length of the threads divided by 100. For paintings of other weaves, when determining the length of the thread in the loop using the standard method of dissolution, use the formulas given in [6].

Using the developed software, the force required to extract the loop from the structure of the knitted fabric is automatically determined, and a graph of the load versus time is constructed. Next, the effort is recalculated per unit length of thread in the loop.

The method determines the fastening of the loop in the structure of a knitted fabric. The data obtained during the test are an indirect characteristic of the stability of the structure of a knitted fabric.

The method is carried out on an automated device (figure 2) as follows. Cut a sample 1 from a knitted fabric in the form of a square with a side of 50 mm. The sample is fixed in frame 2 (figure 1, figure 2). The frame with the sample is mounted on the force sensor 3 of the device. The loop of the knitted fabric is hooked 4, the lower end of which is fixed in the clamp 5. When lowering the clamp 6 using the stepper motor 7, the sensor 3 senses the force necessary to remove the loop from the sample of the knitted fabric and transmits the information to the computer 8. Before the experiment calibration of the device, the conversion coefficient is entered in the control program.

Design solutions, the basis of the method for determining the fastening of the loop in the structure of a knitted fabric using the developed device, allows to achieve the following technical results:

- obtaining numerical data determining the resistance of the elements of the knitted fabric to the violation of the loop structure;

- forecasting the stability and rationality of the structure of knitted fabric;

- improving the reliability and accuracy of the results through the use of automated devices and computer technology;

- reducing the time spent on the experiment by obtaining numerical test results in an automated mode.

The amount of force (F _n , mN) required to remove the loop from the structure of the knitted fabric is automatically determined by the program. The determination algorithm is as follows:

- the signal from the force sensor 3 (figure 2) enters the analog-to-digital Converter and then to the computer;

- the control program directly reads the converted digital signal, which corresponds to the force, multiplies it by the sensor conversion coefficient to obtain the force dimension F _n , mN;

- the control program substitutes the obtained value of F _n in the formula, which determines the specific fastening of the loop in the structure of the knitted fabric, f _n ;

- a data file is generated;

- a graph of the dependence of effort over time is built.

Next, the force required to extract the unit of length of the thread in the loop is calculated (specific fastening of the loop in the structure of the knitted fabric, f _n , mN), according to the formula:

,

,

where f _n - loop fastening in the structure of a knitted fabric, mN / mm;

F _n - the force required to remove the loop from the knitted fabric, mN;

l _n - the length of the thread in the loop, mm

The strength group determines the stability group of the structure of the knitted fabric (unstable, medium stable, stable). As a result of experimental studies, it was found that for fabrics of different fibrous composition, it is advisable to establish various numerical values of the boundaries of the stability groups of the structure of the knitted fabric. The numerical values of the boundaries of the stability groups of the structure of a knitted fabric (unstable, medium, stable) were established as a result of a study of the deformation properties of the fabrics. As a criterion for assessing the stability of the canvas structure, the value of residual deformation after a single and multiple operational tension was used. The performed pair correlation analysis showed a close relationship between the loop fastening index in the structure of the knitted fabric and the value of the residual deformation after a single and multiple operational tension.

The data obtained confirm the possibility of using the proposed loop fastening characteristics for the design of rational structures of knitted fabrics that are resistant to operational loads.

For linen knitted fabrics, the boundaries of the stability groups of the structure of the knitted fabric are determined. Table 1 shows the gradation of linen knitted fabrics on the stability of the structure of the knitted fabric.

The results of an experimental study of the fastening of the loop in the structure of the fabric for linen knitted fabrics according to the proposed method are shown in table 2. As an example, figure 3 shows the graphical dependence obtained during the experimental study of the fastening of the loop in the structure of linen knitted fabric No. 1.

Table 1 The stability of the structure of linen knitted fabrics The stability group of the structure of knitted fabrics Loop fastening in the web structure, f _n , mN / mm unstable <100 medium stable 100-150 sustainable > 150

table 2 The results of the study of loop fastening in the structure of a knitted fabric Knitted fabric No. Name of textile material The surface density of the canvas, g / m ² Density (number of loops per 100 mm) The length of the thread in the loop, l _p , mm The force required to remove the loop, F _p , mN The fastening of the loop in the structure of the canvas, f _p , mN / mm Group of stability of the web structure horizontal P _g vertical P _in one Purebred knitted fabric 334 29th fifty 11.5 1274 111 medium stable 2 Purebred knitted fabric 419 29th 38 12.0 1470 147 medium stable 3 Purebred knitted fabric 353 33 60 10.0 981 81 unstable

List of sources used

1. Dodonkin Yu.V., Kiryukhin S.M. Assortment, properties and quality assessment of fabrics. - M.: Light Industry, 1979. - 240 p.

2. GOST 28073-89. Sewing products. Methods for determining the breaking load, lengthening of filament seams, expandability of the fabric threads in the seams.

3. GOST 3814-81. Cloths are textile. Method for determining flakeability.

4. GOST 29104.18-91. Technical fabrics. Method for determining flaking resistance.

5. Flerova L.N. Material science of knitwear [Text] / L.N. Flerova, G.I. Surikov. - M.: Light Industry, 1972. - 184 p.

6. GOST 8846-87. Cloths and knitwear. Methods for determining linear dimensions, skew, number of stitch rows and stitch columns and length of thread in the loop.

Claims (1)

A method for determining the fastening of a loop in the structure of a knitted fabric, according to which a sample from the test knitted fabric is subjected to tests by extracting one loop from the structure of a knitted fabric according to a pre-calculated length of a thread in a loop, followed by calculation of the force required to extract a unit of length of a thread in a loop using the formula:

,
where f _n - loop fastening in the structure of a knitted fabric, mN / mm;
F _n - the force required to remove the loop from the knitted fabric, mN;
l _n - the length of the thread in the loop, mm

Images