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THE IMPACT OF VARIOUS DEFECTS IN DETERMINING IP
QUALITY
Mahmudova Gulshanoy Ozodjon qizi
Fergana Polytechnic Institute, Uzbekistan
E-mail:
Abstract
This article analyzes the impact of various types of defects on yarns. The
formation of thickened yarns due to sliver breakage in natural and synthetic fibers is
discussed. Such defects mainly result from improper reconnection of the sliver after
it breaks. The study investigates the causes of these breakages and evaluates
preventive measures aimed at reducing their occurrence. The results provide insights
into improving yarn quality by minimizing sliver breakage through optimized
mechanical adjustments and process control.
Keywords
: defects, luminosity, capacity, mass, unevenness, motor, air
pressure, mechanism.
Introduction
Currently, Saurer Czech and Saurer Group, in cooperation with other
companies, produce many models of pneumatic spinning machines under the BD
brand. One group of these machines is manufactured under the BD 300 model
(models BD 310, BD 320, BD 321 and BD 330). These machines are designed for
spinning yarn on cotton fiber.
In order to improve the quality of yarn, facilitate maintenance and increase the
economic efficiency of production, the following mechanisms are installed in the
machines:
- "third arm" - a mechanism for removing bobbins filled with yarn, installing
an empty bobbin and providing a spare winding of yarn on its right side;
- a connecting lever or semi-automatic connecting mechanism to facilitate the
connection of the yarn in case of its breakage;
- control device – serves to display the set and actual parameters of the machine,
to set, perform technological calculations, control the spinning start process, and
monitor the operation of the machine. On the display in the control mechanism, all
“JOURNAL OF SCIENCE-INNOVATIVE RESEARCH IN
UZBEKISTAN” JURNALI
VOLUME 03, ISSUE 05, 2025. MAY
ResearchBib Impact Factor: 9.654/2024 ISSN 2992-8869
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indicators are displayed in the prescribed order or reset. It is possible to select the
necessary language for communication (English, German, French, Russian, etc.);
- device for starting the spinning process;
- lights indicating yarn breakage;
- pulleys, belts for changing speeds in the transmission section;
- information gathering system (in some machines);
- air pressure change warning lights (in some machines);
-additional engine for adjusting the speed of rotation of the camera (in some
machines);
- automatic air pressure adjustment device (in some machines).
The machine does not differ much from previous machines in terms of its
technological structure. In it, the principle of operation of the processes of wick
supply, discretization, transmission and yarn formation, yarn winding is
implemented in the same way as in previous machines. However, due to the use of
new technical solutions in the mechanisms and devices that perform these processes,
their parts, transmission of motion to the machine and its control, the quality of the
yarn is improved, the size of the productivity increases, and economic efficiency
increases. This is a very important result.
Thickened threads are formed as a result of a broken cocoon, with its end
becoming entangled with another cocoon. The main defects found in raw silk are
various, and include: short thickened areas, longer densely packed areas, protruding
and displaced silk ends on the surface of the thread, and the spiraling of one or more
threads around the middle threads when the cocoon threads are stretched differently.
In addition, defects also affect the weaving process. That is, yarn thickening is
the presence of warp or weft threads in the fabric with a linear density higher than
the linear density of the main fabric. Local thickening is the thickening of warp or
weft threads in short sections. Separated yarn - defects such as warp or weft threads
that differ in tension, twist, color or cross-section from neighboring threads also
affect the weaving process.
The following defects occur in artificial yarns: uneven or insufficient spinning
of viscose yarns (occurs when the yarns are formed in excessively acidic pickling
baths), different coloration of the yarns (occurs when the spinning solution is not
homogeneous and is dirty), hairiness of the yarns - the ends of broken and isolated
yarns protruding from the surface of the yarn (occurs when the spinning solution is
“JOURNAL OF SCIENCE-INNOVATIVE RESEARCH IN
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ResearchBib Impact Factor: 9.654/2024 ISSN 2992-8869
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not well cleaned of air bubbles and the solution is not very viscous), twist - wavy
twisting of the yarns in the short section.
The appearance of cotton yarn is checked according to the GOST 15818-80
standard; short-section unevenness, knots (thinning, thickening); visible to the eye,
parts of the seed, leaves, bark fibers, fragments of cobs, various external defects, etc.
They are divided into classes A, B, V. Unevenness means that the yarn and threads
are not uniform in thickness, curling, curling and elongation. To determine
unevenness, the yarn is compared with a standard (sample) stored in the laboratory,
and the indicators are measured several times in appropriate instruments and put into
appropriate formulas, and the unevenness is calculated as a percentage. Yarns made
of chemical fibers and staple fibers are more uniform in terms of their properties
than complex yarns made of natural fibers and natural silk.
At least 10 tubular yarns are selected to determine the class of spun yarns.
The entire product unit is wound on a screen winding device with a gap of 1.5
mm on a black board up to a length of 100 m, and the yarn class for each side is
determined by comparing it with the reference indicators. The winding of the spun
yarns on the board is carried out evenly. To easily calculate the defects in the spun
yarns, a black cardboard template is placed on the wound yarn. This template is
divided into 10 rectangles. The height of each rectangle is 20 mm, and the width is
designed to view 25 wound yarns. The sum of the defects of the yarn 5 m long on
one side and 5 m long on the other is calculated and compared with the table to
determine the yarn class.
“JOURNAL OF SCIENCE-INNOVATIVE RESEARCH IN
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Figure 1. Illustration of the NOC device for determining the purity of
yarn.
A cardboard template is placed on the board on which the yarn is wound. This
template has 10 rectangular holes. The length of the yarn inside the rectangle is 5 m.
The defects on the yarn inside the rectangle are counted from both sides of the
template. Based on the result obtained, the number of defects per 1 g of yarn is
determined by the following formula.
𝑛
1
=
10
3
∗ 𝑛
𝑇 ∗ 𝐿
where: T-yarn linear density, tyex; n-number of defects in 10 m of yarn; L=10
m.
Recently, a number of methods and equipment designs have been created to
control product defects in the spinning industry. Currently, visual, gravimetric,
mechanical, capacitive, photoelectric and other types of measuring methods are
widely used for these purposes.
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The methods and devices of the company "Sylveger" (Switzerland) for
detecting defects in spun yarns occupy one of the highest places. One of the most
common devices for detecting defects in spun yarns during the spinning process is
the "Uster-Tester". The following characteristics are obtained on the device: the
most common defects in 1 km of spun yarn - thinning (-20, -40, -50, -80 %);
thickened (+35, +50, +70, +100%), knots (+140, +200, +280, +400%). The
equipment has high performance and diagnoses the condition of equipment in the
technological process.
Another device for determining the purity of yarns is the AOPN-5 photocell
type. In the photocell type, defects are detected based on the passage of light between
various types of photocells (vacuum, phototriode, photoamplifier, etc.) and a light
source. For example, defects in the device are divided into: large thickening, yarns
with a diameter of 1.5, thickening, yarns with a diameter of more than 1.5 and a
length of more than 10 cm; very thickening, yarns with a diameter of more than 2:
thinning, yarns with a diameter of less than 0.6 and a length of more than 10 cm. In
addition, devices with capacitive sensors are also used to determine and control the
purity of yarns. The test yarns are passed through a plate capacitor, then its resistance
changes. The resistance of the capacitor is inversely proportional to its capacitance,
and the greater the mass of the yarn, the smaller it is.
Conclusion: In conclusion, the increase in irregularities as a result of yarn
breakage causes defects in yarn. Yarn irregularities affect the quality of yarn.
Therefore, improving the equipment for detecting yarn irregularities and cleanliness
and using devices designed with sensors and photocells will detect defects and
improve the quality of yarn.
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ResearchBib Impact Factor: 9.654/2024 ISSN 2992-8869
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