RU2495416C2 - Method of determining crease retention of textile fabrics - Google Patents

Abstract

FIELD: textiles, paper.

SUBSTANCE: in implementation of the method the sample is loaded, unloaded, and after resting the crease retention is determined, and the immersion is carried out after the formation of non-oriented folds, followed by digital photosurveying of the non-creasy and creasy sample, transfer of the image on the computer screen in real-time and processing of digital images by highlighting areas of the integrated brightness and comparison of the intensity of the brightness distribution of areas of images in these areas, and the degree of crease retention is judged by the coefficient calculated by the formula: $$\text{K}=\frac{{\text{S}}_{\text{0}}-{\text{S}}_{\text{k}}}{{\text{S}}_{\text{0}}}\ast \text{100}\text{,}$$

where S₀ is value of the image spectrum of the non-creasy sample in the middle area of the histogram,%; S_k is the value of the image spectrum of the creasy sample in the middle area of the histogram, %.

EFFECT: modeling of real process of creasing of textile materials in garments is achieved, increasing reliability of the test results due to the use of a more objective criterion of crease retention.

1 ex, 2 tbl, 3 dwg

Description

The invention relates to textile materials science and is intended for an objective assessment of creasing of materials for clothing in the textile and light industries, and can also be used for research, periodic and certification tests.

A known method for determining the crease of textile materials, which consists in the formation of a sample of the material, its crushing under load, unloading and assessment of crease by changing the geometric dimensions of the sample [1]. The sample is formed in the form of a cylinder by stitching a rectangular piece of material. A load is applied from above to a vertically mounted sample. To assess creaseability, measure the height of the sample before and after application of the load. The disadvantages of this method are the complexity of preparing the test sample, the effect of the seam on the geometric dimensions of the sample after recovery and insufficient imitation of the crushing process that occurs during operation of the products, which reduces the objectivity of the test results.

The method that most accurately imitates the process of crushing materials in clothes is the organoleptic (expert) method for assessing creasing, where the formation of folds in the sample is carried out by crushing the sample with the hand of an expert in different directions [2]. However, this method does not allow to obtain the same force of influence on the sample. At the same time, the visual assessment of creasing is subjective and characterized not by a quantitative, but by a descriptive assessment (crush-resistant, crush-free, crumpled), which reduces the objectivity of the results.

There is a method for determining the creasing of textile materials, according to which a sample in the form of a circle with a radius of 30 mm is fixed, loaded, forming non-oriented folds, unloaded and measured after rest. The creasing in the given directions is estimated by the change in the geometric dimensions of the sample [3]. The disadvantage of this method is the lack of simulation of the real process of non-oriented crushing, due to crushing of the sample in only four directions. The principal disadvantage of this method is that the assessment of creasing by changing the geometric dimensions of the sample is not objective enough, since the essence of creasing is the formation of folds, the edges of which sharply separate two adjacent parts of the material surface that reflect light differently, as a result of which the folds are very noticeable and unpleasant for the visual perception, especially when many folds form an uneven surface [4].

According to the criterion for evaluating the crease, the closest to the proposed method is a method for determining the crease of a pile of tissue [5]. In this method, simultaneously using a video camera, images of crumpled and crumpled sections of pile fabric are obtained, and an average degree of grayness of digital images is used to assess creaseability. The fundamental disadvantage of this method is that the use of the average grayness indicator is not reliable enough, since in the crumpled sample the dark areas can compensate for the light areas that occur during crushing due to unequal light reflection. In this case, the average grayness of the crumpled and crumpled area may be approximately the same.

The most common in scientific practice is the standard method for determining the crease of textile fabrics with oriented collapse on the SMT-10 device [6]. This method is selected as a prototype. The ordered folding of flat T-shaped samples proposed in the standard method (even for different directions of application of the load) does not correspond to the non-oriented collapse that occurs during the operation of clothes. Therefore, the method of oriented wrinkling can be purposefully used to predict the “positive” crease of fabrics, in particular, when assessing the stability of hard folds embedded in the design of a garment for aesthetic purposes. The complex configuration and small linear dimensions of the samples (S _slave. = 1 cm ² ) leads to the appearance of a "boundary effect", which has a significant impact on the test results, mainly distorting them.

The technical result of the claimed invention is the approximation of the test conditions to the conditions of the actual process of shearing textile materials in garments, increasing the reliability of the test results through the use of a more objective crush criterion.

The specified technical result in the implementation of the method is achieved through the application of the method of recognition of optical images. As a criterion for creasing, the ratio of the brightness of the sections of the digital image of the crumpled and crumpled samples is used. According to the proposed method, digital photography of an unmounted sample is carried out with visualization of the image on the computer monitor screen, loading is performed after the formation of undirected folds, then digital photography of the crumpled sample is carried out. Then, on the histograms of digital images of the crumpled and crumpled samples, the areas of integrated brightness (low, medium, high) are highlighted and the intensity of the distribution of brightness of the image sections over these areas is compared. The degree of collapse is determined by the percentage ratio of the brightness of the middle and extreme regions of the histograms of the crumpled and crumpled samples.

The essence of the proposed method for assessing creasing is to quantify the light, medium and dark sections of the canvas that occur during crushing due to unequal reflection of light. Permanent canvas has a certain average brightness, there are no very light and very dark areas.

Using existing universal graphic editors (for example, Photoshop), the brightness histograms are established on the histogram of the digital image, in which the spectrum of the unwashed sample is completely (97-100%) located in the middle region of the histogram. The spectrum of the crumpled canvas due to the presence of lighter and darker areas is expanded relative to the average region of brightness set for the crumpled sample. According to the magnitude of the shift of the spectrum boundaries of the crumpled sample to the extreme (light and dark) regions, the creaseability of the material is estimated.

The degree of creasing is judged by a coefficient determined by (formula:

$$\text{K}=\frac{{\text{S}}_{\text{0}}-{\text{S}}_{\text{k}}}{{\text{<figure-callout id="0" label="S" filenames="00000008.png" state="{{state}}">S</figure-callout>}}_{\text{0}}}\ast \text{one hundred}\text{,}\left(\text{one}\right)$$

S ₀ - the magnitude of the spectrum of the image of the unwashed sample in the middle region of the histogram,%;

S _{k the} value of the spectrum of the image of the crumpled sample in the middle region of the histogram,%.

The method is implemented using the device represented by the following drawings.

Figure 1. A device for determining the creasing of textile

paintings (a - frontal sectional view; b - top view).

Figure 2. Digital image of the sample (a - uncr; b - crumpled).

Figure 3. Histograms of images (a - uncrutched sample, b - crumpled).

An example of the method

The method determines the creasing of fabrics, knitwear, non-woven materials. The characteristics obtained during testing make it possible to predict the creaseability of various parts of products.

The proposed method is carried out on the developed device (figure 1). Structurally, the device for assessing the crease of textile fabrics is an integrated system consisting of three blocks:

- the mechanism of formation of non-oriented folds in the sample;

- the mechanism of loading and compression of the sample with formed undirected folds;

- a block for obtaining a digital image of a sample in real

time on the computer screen.

Assessment of creasing of textile fabric by the proposed method is as follows. Cut a sample 2 from a textile fabric, for example, a knitted fabric in the form of a circle with a radius of 50 mm and place it on the upper platform 1 of the device. The sample is in a free position on the upper platform 1, while the sliders 5 in the amount of six pieces are located on the outer edge of the sample of the test material and are in the outermost position inside the guide grooves 3 of the upper platform.

Web camera 14, mounted on the screen 19, carry out digital photography of the sample with the transmission of the image in real time to the computer monitor screen.

The formation of non-oriented folds in the sample occurs when six sliders 5 are moved along the guide grooves 3 to the center of the test sample. The elastic material 18, moving simultaneously with the sliders 5, provides a uniform shift of the edges of the test material sample. The movement of the sliders along the guiding grooves is carried out by simultaneously tensioning the flexible rods 8 using the roller 4 of the vertical shaft 7, located between the upper 1 and lower 12 platforms. The rotation of the vertical shaft is transmitted from the flywheel 11 of the horizontal shaft 9 through bevel gears 10 located inside the housing 17 of the device. The return of the sliders to their original extreme position is due to the springs 6.

A removable loading element 13 compresses the sample with formed undirected folds for 15 minutes. Test parameters (force, time of application of load and rest) are set as standard [6]. After the loading time has elapsed, the sample is released from the removable loading element, the sliders 5 by means of the springs 6 are simultaneously moved to the outermost position inside the guide grooves 3. The sample is left for rest on the upper platform 1. After rest, digitally photograph the crumpled sample with a Web camera 14. The lens the digital camera and the lighting device are located at certain angles to the photographed surface of the sample. The magnitude of the angles is determined experimentally to obtain the most contrasting light-shadows of the crumpled sample. In order to provide even greater contrast of light shadows, the device is surrounded by a screen 19.

The received digital images of the wrinkled and crumpled sample are transmitted in real time to the computer monitor screen. Further, using the existing universal graphic editors, optical images are processed, and the obtained information is converted into quantitative characteristics of the crease of a textile web.

Design solutions underlying the method of determining crease using the developed device can achieve the following technical results:

- imitation of the real process of crushing parts of clothing due to non-oriented crushing of a sample of material and subsequent loading and compression;

- increasing the objectivity of the results due to the use of the ratio of the brightness of the sections of the digital image of the sample material before and after crushing as a criterion for creasing;

- ensuring the accuracy of estimates through the use of digital technology in the receipt and processing of input and output data.

As an example, figure 2 shows digital images of samples of linen knitted fabric by weaving combined reps before and after shearing. The histograms of the crumpled and crumpled samples shown in FIG. 3 show that the spectrum of the crumpled sample (FIG. 3a) is concentrated in a narrower region compared to the spectrum of the crumpled material sample (FIG. 3b). Using the histogram of the digital image of an unbroken sample for each color channel, the left and right boundaries of the spectrum are determined. Next, the average value of the boundaries is calculated over three color channels (in this case, the left border corresponds to a brightness of 95, the right one - 225). We consider this region to be a region of medium brightness, and in it the spectrum of an unbroken sample is usually located at 97-99%, since there is scattering of points due to the weaving of the canvas. On the left is a region of low brightness (from 0 to 95), on the right is a region of high brightness (225-255).

The boundaries of the middle brightness region are transferred to the histogram of the digital image of the crumpled sample. Next, the magnitude of the shift of the spectrum of the crumpled sample beyond the color boundaries of the average brightness region specified by the standard is determined. In the example under consideration, the spectrum of the crumpled sample is located in the middle brightness region, which is 82% based on the unreached sample, the shift of the spectrum to the low brightness region is 1.2%, and to the high brightness region it is 16.8%. The calculation of the coefficient of smnapnosti of the investigated canvas is performed according to the formula (1).

$$\text{K}=\frac{\text{99}\text{, 6}-\text{82}}{\text{99}\text{, 6}}\ast \text{one hundred}=\text{17}\text{, 67\%}$$

The results of evaluating crease by histograms of digital images, using the example of linen knitted fabric by weaving combined reps, are presented in table 1. Table 2 also shows the results of determining crease of other textile fabrics by standard and proposed methods.

Table 1 Spectral Analysis Results Brightness area The boundaries of the integral brightness area (for this canvas) The value of the spectrum in the integral region of the histogram,%. uncrossed sample crumpled sample Low (dark) 0-95 0.3 1,2 Average 95-225 99.6 82.0 High (light) 225-255 0.1 16.8

table 2 The results of the study of textile materials for crushing Name of textile material The standard method [1],
(coefficient of crease resistance,%) The developed method (crease rate,%) by lenght in width Cotton knitted fabric weaving 72 64 twenty Thin weave knitted fabric combined reps 83 71 17.6 Synthetic yarn knitted fabric 92 85 7.5

List of sources used

1. Soloviev A.N., Shakhbazyan V.V. Evaluation of the creaseability of textile fabrics with multiple undirected crushing of cylindrical samples. / Izv. Universities. Technology of the textile industry, 1976, No. 4. From 9-13.

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

3. A method for determining the crease of textile fabrics [Text]: US Pat. No. 2189588 dated 09/20/2002, Ros. Federation: 7 G01N 33/36 / Smirnova N.A., Kostyukova Yu.A., Korabelnikov A.R .; Applicant and patent holder of the Kostroma state technology un-t

4. Keswell R. Textile fibers, yarn and fabrics. M .: Rostekhizdat, 1960.

5. A method for determining the crease of a pile of fabrics [Text]: Pat. No. 2032903 of 12/19/1990, Russian Federation: G01N 33/36 / Piero Julita (IT); Applicant and patent holder Fiat Auto S.P.A. (IT).

6. GOST 19204-84. Cloths textile and piece products. Methods for determining crush resistance. M .: State. com by standards. - 5 sec.

Claims (1)

A method for determining the crease of textile fabrics, according to which the sample is loaded, unloaded, and after rest, the crease is determined, characterized in that the immersion is performed after the formation of undirected folds, followed by digital photography of the crumpled and creased sample, transferring the image to a computer screen in real time and processing digital images by allocation of areas of integrated brightness and comparison of the intensity of the distribution of brightness of image sections in these areas, and the degree of creasing and judged by a coefficient calculated by the formula
$$\text{K}=\frac{{\text{S}}_{\text{0}}-{\text{S}}_{\text{k}}}{{\text{S}}_{\text{0}}}\cdot \text{one hundred}\text{,}$$

where S ₀ is the magnitude of the spectrum of the image of the wrinkled sample in the middle region of the histogram,%;
S _k - the value of the spectrum of the image of the crumpled sample in the middle region of the histogram,%.

Images