Uster Evenness Research Articles

A New Photoelectric Device for the Measurement of Yarn Diameter and Yarn Evenness Part III: Computer-aided On-line Measurement of Yarn Evenness on the Ring-spinning Frame

A new on-line measurement system, Onlineven, based on photoelectric principles, is evaluated for measuring yarn evenness. Descriptions of the sensor device used have been presented in Parts I and II of this series. Yarn specifications (linear density, twist) and measurement positions are the main topics discussed. Comparisons between Onlineven and the Uster Evenness Tester are also discussed. The results show that it is possible to use the Onlineven on-line-measurement system with yarn-guide wheels for the measurement of the yarn evenness at various linear densities (12.9–29 tex) and twists (590–1396 turns/m) at position 2. The differences in yarn evenness between Onlineven and Uster Tester III are all less than 5%. The mean deviation of yarn evenness of this system is small and limited to ±%.

A New Photoelectric Device for the Measurement of Yarn Diameter and Yarn Evenness. Part I: Improvement of the Variance of Radiant Intensity by Using the Area-compensation Method (ACM)

The diameter measurement of a moving and vibrating yarn with a photoelectric sensor device is difficult. Two main restrictions are concerned with the photoelectric measurement of yarn diameter and yarn evenness. One is the inhomogeneous radiant intensity of the emitted light on the sensor device, and the other is the irregular shape of the yarn cross-section. The improvement of the variation of radiant intensity in the horizontal light slot so as to obtain a homogeneous radiant flux in the test section by using the area-compensation method (ACM) is discussed in this study. The radiant-intensity distribution of an infra-red-emitting radiation was investigated by using the cubic-spline interpolation after the light had penetrated through a convex lens and a rectangular light slot. The ACM was then applied for obtaining a modified light slot, which was added to the convex lens. The ACM was developed according to the concept that the radiant flux is equal to the product of the radiant intensity and solid angle. Provided that the yarn diameter is constant, it is easy to determine the variance of an inhomogeneous radiant intensity. A steel bar of diameter 1 mm was applied for simulating the yarn diameter in this study. If the radiant intensity in this case is homogeneous, the projectile irradiance on the sensor would remain constant when the simulating yarn moved in the test section. The yarn diameter could be measured exactly in the homogeneous test section no matter how the yarn moved and vibrated. The coefficient of variation (CV%) of the radiant intensity decreased from 8.3% to 0.4% when the ACM was used. This sensor device was applied to measure the yarn-evenness variation of a 13.9-tex ring-spun yarn. The CV% decreased from 17.8% to 15.4%. Under the same testing conditions, the CV% was 14.3% with the Uster Evenness Tester. The variance of radiant intensity has accordingly been improved with the ACM.

Efeito da torção na regularidade e na quantidade de neps em fios de algodão de títulos Ne20, Ne30 e Ne40

Estudaram-se a regularidade e a quantidade de "neps" em fios de algodão de títulos Ne20, Ne30 e Ne40 para diferentes coeficientes de torção, representados pelas constantes 3,4, 3,6, 3,8, 4,0, 4,2, 4,5 e 4,7. Utilizaram-se, para tanto, três variedades paulistas de algodoeiro: IAC 16, IAC 13-1 e IAC 17. Obtiveram-se a regularidade dos fios e a quantidade de "neps" por meio dos resultados fornecidos, respectivamente, pelo integrador e pelo contador de imperfeições, ambos da linha Uster Evenness Tester. Com base nos resultados, concluiu-se que, ao aumento do número de torções do fio, correspondeu o crescimento do número de "neps", o qual se intensificou, sucessivamente, nos títulos Ne20, Ne30 e Ne40, e, notadamente, nas variedades com tendência acentuada para essa anormalidade. Não se verificou efeito da torção na regularidade do fio. Títulos mais altos resultaram em aumentos na irregularidade e na quantidade de "neps", sobretudo em relação à IAC 13-1, mais sujeita a esses defeitos.

A Microprocessor-Based System for Obtaining Variance-Length Curves of Jute Yarns

A microprocessor-based system for deriving variance-length curves in conjunction with Uster evenness tester has been described with particular reference to jute yams. Reliable variance-length curves can be obtained easily, and the higher CVs often encountered in jute yarns do not pose any problem. Thick and thin portions of the yarns can also be counted without additional circuitry.

Comparison of Medium and Long Term Irregularities in Ring Spun and Open End Spun Yarns

The medium and long term irregularities in ring spun and open end (OE) spun yarns are compared. The medium term irregularity was measured by an inert test in an Uster Evenness Tester using different material speeds, and long term irregu larity was assessed using the cut and weigh method. The results show that not only short and medium term irregularity but also long term irregularity are brought down substantially in OE spinning. This leads to the significant conclusion that the ir regularity added in a ring spinning system comes not only from drafting waves but also from other causes which are absent in OE spinning.

9—THE USE OF MICROCOMPUTERS IN DERIVING VARIANCE–LENGTH CURVES

An exploratory method to determine the usefulness of microcomputers, in conjunction with the Uster Evenness Tester, is described. Details are given of the problems involved, and of the steps taken to overcome them, in outline, with reference to more complete work. Derivation of the information for generating the complete curve requires less than 1 hr, and subsequent analysis time (from 2 to 4½ hr in this case) is governed solely by the speed of operation of the microcomputer selected. Tests indicate that the method is a reliable one, and typical uses (the comparison of a good with a bad yarn and of a carded with a drawn silver) are reported.

A Continuous Monitor of Yarn Uniformity During Melt Spinning

A yarn-mass variation instrument is described that can be used to provide a continuous monitor of yarn uniforn ity directly on a melt-spinning machine. The mass uniformity of melt spun yarns is a parameter of commercial importance. but uniformity has traditionally been measured off line, at low speeds, and on only a small portion of the yarn package with a Uster evenness tester. The on-line instrument, an Asahi GQ system, gives an indication of yarn uniformity during spinning via 3 readings that are calculated from the varying yarn modulation of a constant AC signal. 'I'he Asahi readings can be related to the conventional Uster values obtained after the yarn has been spun. The uniformity readings can also determine the nature of the mass nonuniformities arising during spinning and can relate the disturbances to specific portions of the process. The mass variation instrument can therefore be used for on line optimization of varn uniformity in the melt spinning process.

Dynamic Response Characteristics of the Uster Evenness Transducer

The dynamic response characteristics of the evenness transducer of the Uster Evenness Tester was analyzed by studying the transducer response to special test tapes and yarns prepared with various step and periodic irregularities and transported through the transducer at a range of speeds. Limits on the maximum transport speed for reliable relative measurement of various types of random and periodic irregularities were established.

How Yarn Twist Affects Yarn Uniformity and Imperfections

The improvement in uniformity and decrease in imperfections obtained with decreased twist might be due to the measuring principle of the Uster Evenness Tester rather than to any spinning phenomena.

Some Observations on the Irregularity of Roving as Measured on the Uster Evenness Tester

Some Observations on the Irregularity of Roving as Measured on the Uster Evenness Tester

Fiber-to-Yarn Strength Translation of Acrylic Spun Yarns

A method is described for accurately determining the ultimate tenacity of an acrylic yarn and its fiber-to-yarn strength translation efficiency. Both of these values are essentially independent of the nonuniformity of the denier of the yarn. The method con sists of determining the denier of thin segments of yarn with the Uster Evenness Tester and then finding the tensile strength of these same yarn segments with the Instron Tensile Tester. Differences between ultimate yarn tenacities in these thin yarn sections and tenacities based on yarn skein and single-end strengths are also examined.

Capacitive Measurement of the Count of Worsted Wool Strands with a Uster Evenness Tester

A method is described by which the linear density of worsted strands. consisting of 100% wool, can be determined capacitively by using a Uster evenness tester. A statis tical comparison is given of the linear density of a few strands, as determnied by this method, with their actual weights per unit length. The method seems to provide results with an accuracy within the limits normally demanded by mdustry.

Contribution to the Study of the B–L Curve of Cotton Yarns

For the worsted system of processing Grosberg [9] has developed an equation which makes possible the derivation of the variance–length curve of a yarn from the total variance of each of the slivers made during the manufacture of the yarn. The present study is an attempt to evaluate the suitability of this equation for cotton processing. For this purpose, two cottons were spun to 40s and one to 30s using the orthodox system of processing consisting of 3 speed frame passages. The irregularity of the material at different stages of processing was determined with the Uster evenness tester, and the B–L curve of the yarn was deduced using Grosberg's equation. The actual B–L curve of the yarn was also determined with the evenness tester by the “inert test” method. On plotting the results it is found that there is considerable discrepancy between theory and experiment—the predicted curve is seen to be too high in every case. The reasons for this discrepancy are discussed. A preliminary study on two yarn samples showed that there is good agreement between the B–L curves obtained by the Uster evenness tester and the cut-and-weigh method. The log B ( L)–log L plot is found to be fairly linear, except for short lengths, for cotton yarns.

Slide Rule for Correcting Uster Evenness Calculations

Slide Rule for Correcting Uster Evenness Calculations