CS216595B1 - Method of measuring reliability of yarn feeders on textile, especially circular knitting machines - Google Patents

Abstract

The invention is intended for use in the textile, especially knitting industry in the production of knitted fabrics, where it is necessary to determine the reliability of the function of yarn feeders. The subject of the invention is a method of measuring the reliability of the function of yarn feeders suitable for determining the values of the untension of the fed yarn before and after the feeder. The principle of this method consists in that after determining the basic values of the tension of the fed yarn before and after the feeder, comparative values of the tension of this fed yarn before and after the feeder are determined, based on the use of simulated values of obstacles representing real conditions during knitting. The simulated values of obstacles represent elastic shocks and rigid shocks. It is possible to determine the comparative values of the fed yarn before and after the feeder simultaneously.

Description

(54) Method of measuring the reliability of the function of yarn feeders on textile, especially circular knitting machines

The invention is intended for use in the textile, especially knitting, industry in the production of knitted fabrics, where it is necessary to determine the reliability of the function of thread feeders.

The subject of the invention is a method for measuring the reliability of the function of yarn feeders suitable for determining the values of the untension of the fed yarn before and after the feeder. The principle of this method consists in that after determining the basic values of the tension of the fed yarn before and after the feeder, comparative values of the tension of this fed yarn before and after the feeder are determined, based on the use of simulated values of obstacles representing real knitting conditions.

The simulated obstacle values represent elastic shocks and rigid shocks. It is possible to determine the comparative values of the yarns fed in front of the feeder and behind the feeder simultaneously.

The invention relates to a method of measuring the reliability of the function of thread feeders on textile, especially circular knitting machines, which is suitable for determining the tension values of the thread fed into the machine before and after the feeder.

Yarn feeders are an important part of the yarn feeding system on textile machines. On circular knitting machines, the quality of the knitted fabrics produced directly depends on the reliability of their function, both in terms of maintaining the same yarn consumption per eye in individual working systems of the machine, and because of the desire to eliminate fluctuations in the tension of the fed yarn caused, for example, by threading the yarn on the eyelets, twisted knots, damaged surface of the tube or winding the yarn around the guiding elements. From the point of view of uniformity in feeding the yarn into the working system of the knitting machine, it is possible to characterize fluctuations in tension during knitting as obstacles expressed in elastic and rigid shocks when unwinding the yarn from the bobbin.

Elastic shocks occur when the thread is unwound from the spool, e.g. when the thread catches on a knot on the surface?’?».

winding or on entangled dirt. With these elastic shocks, the thread usually overcomes the obstacle during unwinding without breaking the thread.

Rigid shocks also occur when unwinding the thread from the bobbin, e.g. in the case of an underwound bobbin or a damaged bobbin, where the obstacle is of such a nature that the thread is unable to overcome it, resulting in its breakage.

The term temporarily increased tension of the fed thread is understood to mean an obstacle that results in a significant increase in the tension of the thread in the area in front of the feeder, e.g. thread wrapping around the guide part, clogging of the guide eye of the take-off, etc. In this case, the thread usually does not break.

Depending on the reliability of the feeder function, the voltage downstream of the feeder, i.e. in the section between the feeder and the machine's working system, will increase if the feeder is unable to eliminate the increased voltage.

From the point of view of material processability, knit quality and machine operation, it is more advantageous when the tension after the feeder is equalized, i.e. when the feeder is able to equalize the increased tension.

Many types and designs of feeders are known for textile machines intended for mass production and for special purposes. According to the purpose and various designs, feeders can be divided, for example, according to their drive into individual and central or according to the method of feeding the thread into the working system of the machine into magazine and belt.

Belt feeders have undergone rapid development recently and new solutions and principles in the design of feeders are constantly appearing, which proves that the problem of thread feeding has not yet been optimally solved. The well-known method of measuring the reliability of the function of thread feeders on a circular knitting machine is based on simply determining the tension values of the fed thread using tensiometers of various designs, e.g. mechanical, electronic, with the tension values measured in front of the feeder and behind the feeder. However, this method does not allow to assess the real reliability of the feeder function, since most of the known types of feeders are able to eliminate small fluctuations in the tension of the fed thread. Only when obstacles occur in the form of elastic and rigid shocks, or when the tension of the fed thread is temporarily increased, can deficiencies in the design and function of individual types of feeders be detected, which is a valuable tool for knitting machine manufacturers.

The aim of the invention is to enable the optimal selection of the type of feeder capable of reliably eliminating fluctuations in the tension of the yarn fed to the working system of the machine even under extreme conditions, without worsening the quality indicators of the knitted fabric and for a longer period of time, provided that the values of the shock or increased tension do not trigger the reaction of the yarn tension monitor. The above-mentioned objective is achieved according to the invention due to the measurement of the reliability of the function of yarn feeders, the essence of which lies in the fact that after determining the basic values of the tension of the yarn fed before and after the feeder, comparative values of the yarn fed before and after the feeder are determined based on the use of simulated values of obstacles representing real conditions during knitting, wherein the simulated values of obstacles include commonly occurring elastic shocks and rigid shocks. The method according to the invention can also determine comparative values of the yarn tension by measuring after the feeder with increased basic tension before the feeder.

In a preferred application of the measuring method according to the invention, it is possible to determine comparative voltage levels of the yarn fed in front of the feeder and behind the feeder simultaneously using two sensing heads.

In addition to the optimal selection of the type of feeder for a specific type of textile, especially knitting machine, the solution according to the invention allows assessing the quality of winding by evaluating the type, frequency and size of impacts. The methodology for determining the basic and comparative values of the tension of the fed yarn is simple and advantageous also from the point of view that it does not require special adjustments to the knitting machine, its removal from operation during the measurement of tension values, or the use of a special measuring device in the form of a measuring bench, etc. Practical use of the method of measuring the reliability of the feeder function, the achieved test results and conclusions for assessing the selection of a suitable feeder are given in the following examples.

Example 1

The values of the tension of the fed yarn were determined on a circular knitting machine METIN 0 30, 28 ang., 60 working systems, on which PES Slotera 84 dtex was processed during the measurement at a yarn speed of 152 m/min. The actual measurement of the yarn tension value was carried out by an electronic measuring set Rotschild, consisting of a sensing head, an evaluation unit and a Helcoscriptor recorder for taking a graphic record.

When measuring the reliability of the function of selected single feeders, the basic values of thread tension were determined in the usual way before and after the feeder, after which comparative values of no tension were determined when elastic shocks and rigid shocks occurred before and after the feeder. At the same time, thread breaks were recorded, as well as the frequency and location of the break. 2a In order to create objective and uniform conditions, the thread was guided from the spool through the input eyelet and the disc brake directly to the feeder, uniformly for all types of feeders measured. However, the thread was not guided through the shock monitor in order to exclude its influence on the shock values before the feeder. Elastic and rigid shocks were simulated using a simple device, while in the case of elastic shocks a ball rested on the surface of the spool and the unwound thread had to overcome the force of the spring, as a result of which shocks in the tension of the fed thread were created. These shocks were measured in front of the feeder and behind the feeder and recorded in a graphic record, the evaluation of which provided a true picture of the operation and function of the feeder in question.

In the case of rigid impacts, a spring-loaded spike was inserted into the bobbin winding, which prevented the thread from unwinding. The rigid impacts thus created always caused the thread to break during the measurement. The measurement and evaluation of rigid impacts were carried out in the same way as for the evaluation of flexible impacts.

Table 1 - measurement results of various types of feeders with METIN machines

Typ. Basic tension values x(cN)_Comparative tension values (cM)___ feed. pf _ei j feeder after feeder elastic shocks rigid shocks after feeder thread break after feeder thread break

1 2.45 0.73 2.9 -10.8 17.7 24.5 27.5 X X X 2 2.45 0.73 — 1.96 0 1.96 0 1.96 0

3 2.45 0.73 1.28 1.67 1.47 0 0 • 4 2.70 0.59 w 15.7 0 21.6 0 22.6 X 5 1.47 0.88 2.9 - 14.7 X 29.4 X 29.4 X 32.4 X 6 1.47 2.70 * - - 0 - 0 - 0 7 1.28 2.84 - * 0 - 0 - 0 8 1.08 2.65 3.9 - 14.7 X ' 57.9 X 58.8 X 46.1 - X

Explanations to Table 1

Feeder types:

1- original feeder of the METIN circular knitting machine and additional metal ring

2- modified feeder of circular knitting machine METIN ε with additional rubber ring from front production material and thread wrapping around the feed roller

3- modified feeder of a METIN circular knitting machine with an additional rubber ring made of foreign-made material and thread wrapping around the feed pulley

4- modified feeder of METIN circular knitting machine with additional coffee ring and aluminum oxide coating and thread wrapping around the feed roller

5- Rosén type feeder - modified, without thread wrapping

6- Memminger type feeder - modified and with multiple wrapping of the thread around the metal feeder drum

7-,Memminger type feeder - modified and with multiple wrapping of thread around the plastic feeder drum

6- Rosén type feeder - original design

Thread markets:

x needle breakage o = feeder breakage *

- without interruption

The comparative voltage values before the feeder were the same in all cases, namely for elastic shocks

24.5 cN and for rigid impacts 98.1 oN. For the comparative values of rigid impacts, ae always performed three measurements.

As can be seen from Table 1, from the point of view of measuring the reliability of the function of thread feeders, the most suitable types are number 6 and 7, in which there was no penetration of elastic and rigid shocks behind the feeder, and in which there was always a thread break at the feeder, which is advantageous in terms of the quality of the knitwear and the use of the machine. The measurements also showed that it is possible to mark as unsuitable types of feeders number 8, 5 and 1, in which, on the contrary, there was a significant penetration of elastic and rigid shocks behind the feeder and in all cases a thread break in the needles.

Example 2

The yarn tension values were determined on the same type of circular knitting machine as in example 1, with the difference that PES Slotera 50 dtex was processed at a yarn speed of 187 m/min. The actual measurement of the yarn tension values was carried out with the same measuring device and using the same method and procedure as in example 1.

Table 2 - measurement results of two types of feeders of the METIN circular knitting machine

Type of Core values y tension x (cN) Comparative stress values (cN) feeder before the feeder behind the feeder elastic shocks behind the feeder thread break hard shocks behind the feeder thread break 1 8.8 1.37 - - - 0 4.9 1.47 - - - 0 7.8 . .1.57 -. - - 0 2 0.98 1.96 * β 18.6 XX 3.43 1.96 6.9 0 17.7 X 4.41 2.45 ϊχβ X 14.2 X

Explanations to Table 2

Feeder types:

1- feeder type MPP - 20 - B Memminger

2- feeder type circular knitting machine METIN

Thread breaks:

x = needle breakage by feeder breakage

- = after break

The comparison values before the feeder were the same in both cases, namely 16 cN for elastic shocks and 58.8 cK for rigid shocks. Three measurements were made for the basic and comparison stress values.

According to Table 2, which shows the evaluation of two types of feeders, from the point of view of measuring the reliability of the function of the thread feeders, type 1 of feeder appears to be more suitable, in which elastic and rigid shocks from the feeder did not manifest themselves, and in which the thread broke at the feeder, which is more advantageous in terms of the quality of the knitwear and the use of the machine. On the contrary, based on the measurements performed, type 2 of feeder can be considered unsuitable, since the measurements showed a significant penetration of elastic and rigid shocks behind the feeder β in all cases the thread broke in the needles.

Claims (4)

SUBJECT OF THE INVENTION Method for measuring the reliability of the function of yarn feeders on textile, in particular circular knitting machines, suitable for determining the yarn tension values before and after the yarn feeder, characterized in that after determining the basic yarn tension values before and after the yarn feeder of this filament yarn upstream and downstream of the feeder by using simulated obstacle values representative of the actual knitting conditions. 2. The measurement method of claim 1, wherein the simulation of obstacles representing actual knitting conditions includes resilient impacts and stiff impacts. 3. The measuring method according to claim 1, characterized in that comparative values of the yarn tension downstream of the feeder are measured by increasing the basic yarn tension upstream of the feeder. 4. The measuring method according to claim 1, characterized in that the comparative values of the yarn to be fed are detected in front of the feeder and after the feeder simultaneously.