*lemon*
کاربر فعال مهندسی نساجی
روش های کلی اندازه‌گیری پرزینگی
(منبع : the Indian textile journal)
روش قطبنده‌های متقاطع:
در این روش نور به نخ تابانده شده که یک قسمت به بدنه‌ی نخ و قسمتی به الیاف بیرون زده برخورد می‌کنند. حال این نور پرتوهای شامل پرتوهای پلرایز شده و نشده هستند. سپس یک تحلیلگر که زاویه‌ی صفحه‌ی قطبش آن عمود بر زاویه‌ی تابش پرتو است، فقط به قسمت غیر قطبیده که همان اطلاعات شامل قسمت پرزینه است اجازه‌ی عبور می‌دهد. به این گونه اطلاعاتی از این قسمت به دست می‌آید. کالیبراسیون دستگاه توسط نخی با پرزینگی مشخص انجام می‌شود.
روش سیگنال نوری چسبنده:
این روش در دو مقاله‌ی مجزا بحث شده است که خلاصه‌ی آن به شرح زیر است:
دستگاه دو قسمت دارد، یکی قسمت نوری برای عکس برداری و دیگری قسمت الکترونیکی جهت تبدیل این سیگنال نوری به سیگنال ولتاژی متناسب با آن. البته از یک نرم‌افزار کامپیوتری نیز به منظور تحلیل استفاده می‌شود.
روش آرایه‌ی خطی CMOS:
این روش در حقیقت تکمیل شده‌ی روش قبلی است که به طور کامل کامپیوترایز شده و نتایج آن در مجله‌ی ذیل آمده است:
روش آنالیز تصاویر دیجیتال:
این روش در مقاله‌ی زیر بحث شده است که متأسفانه به اصل مقاله دسترسی پیدا نکردم و فقط خلاصه‌ی آن (البته همراه با اطلاعات جانبی‌اش) را آورده‌ام.
(منبع : the Indian textile journal)
Microscopic Methods
Before instruments were developed, hairiness was measured by viewing the yarn under a microscope. Image of yarn is projected on a screen and number of protruding hairs and loops in a known length are counted. Length of protruding hairs is also measured with the help of micrometer eyepiece scale. From this, total length of hairs per unit length is determined. Pillay[1] projected the yarn on Projectina microscope and counted the number of protruding ends and loops in 10 mm length. Length of protruding fibres is measured by a curvimeter on a tracing of yarn image. Jedryka[2] took photographs of yarn image under microscope with a magnification of 50x. The boundary levels of yarn were marked. Four zones parallel to the boundary line were drawn on either side. The lines were equidistant with space between adjoining lines being kept as half the diameter of yarn. Hairiness is determined by the number of intersections the fibre makes with the lines marking the zone on either side. This method gives the hairiness as per the length of the hairs. About 50 to 100 yarn samples are examined from which average hairiness is determined.
Major difficulty in microscopic methods is in identifying the boundary of yarn. Looped fibres, wild fibres, low twisted portions, variation in yarn diameter and cross-section smudge the boundary. High variation in hairiness is found both within and between bobbins and as a result, large number of yarn specimens has to be examined to get a fairly reliable estimate. This makes the method laborious and time consuming.
Photoelectric Method
Several instruments are available for measurement of hairiness based on photoelectric method.
Shirley-Atlas Hairiness Tester
A measuring head consisting of a photocell placed close to the yarn counts the number of interruptions made by the protruding hairs to an LCD beam. The measuring head is infinitely adjustable from 1 to 10 mm from the surface of yarn. This enables measurement of hairiness as per the length of hairs. Nip rollers at 50 to 300 m/min drive yarn by an electronic variable speed drive. Latest version is operated by a PC. Continuous chart of hairiness can also be obtained through a recorder or printer. A portable battery operated model is available for online measurement of hairiness with a standard measuring head of 3 mm. Portable model will enable detection of spindles giving high hairiness.
Zweigle Hairiness Tester
This also uses a measuring head with a photocell and a laser light source. The instrument measures hairiness of 9 length zones from 1 to 12 or 15 mm fibre length in a single run of the yarn and produces a running chart of hairiness. Faults of a periodic nature can be detected. . The equipment is controlled by a PC, which carries out statistical analysis of the results. There is a facility for checking and matching all the optical channels with the reference value set ex works. Calibration with the yarn that has been checked on a master Hairiness tester is also possible. The above facilities improve reproducibility of results. An automatic bobbin changer up to 24 bobbins is available which makes the instrument fully automatic. Most of the research work on hairiness is based on tests on this instrument.
Meiners Dell Hairiness Tester
The instrument measures simultaneously hairiness of hair lengths from 1 to 10 mm in steps of 1 mm. A single run of the yarn gives hairiness for all lengths at a selected speed. A portable model is also available which enables online measurement of hairiness.
Changling Hairiness Tester
This uses a laser light source and a sensitive integrated photocell for measuring number of projecting hairs. Measurements of hair number for lengths from 1 to 9 mm are possible.
Apart from estimates of number of hairs, length-wise, another parameter that is commonly used is S3 value, which indicates the number of fibres, which protrude beyond 3 mm length.
Uster Tester
Uster Evenness Tester has a hairiness attachment. Measuring field consists of homogenous rays of parallel light from an infrared light source. Scattered light from the protruding hairs of yarn, placed in this field, reach an optical sensor, which converts it into an electronic signal. The body of yarn itself is dark as it is not transparent and so does not contribute to the measurement. The protruding fibres are bright and reflected light from these fibres alone contributes to measurement. Hairiness thus measured is an estimate of total length of protruding fibres in a cm length and is termed as Hairiness index. Hairiness index of 4 means that the total protruding length of hairs in 1 cm length is 4 cm.
Uster has been publishing periodically Uster standards for hairiness based on survey of mills worldwide. While this method has the merit that it gives a single index to characterise the hairiness, it has the drawback that it does not provide information on long length and short length hairs separately. Thus two yarns may have the same hairiness index but one may have more long hairs and fewer short hairs than other. Since long hairs are more objectionable than short hairs, information on the level of hairs as per their length will be more useful. Uster tester further gives coefficient of hairiness over measured lengths 1 cm (normal) 10, 100, 300, 1000, 5000 cm or in other words variance length curve of hairiness. Presence of periodicity in hairiness can also be determined by spectrogram of hairiness.
While some studies have shown a good correlation between hairiness by Shirley hairiness tester and Uster tester[3], others have found little association[4]. While Uster hairiness index is based on all hair lengths, S3 is based on hairs 3 mm and longer. So these two measures will correlate well only when number of hairs vs hair length relation is similar. Good correlation exits between Uster hairiness index of compact and normal ring spun yarns spun from a number of cottons. But Zweigle hairiness S3 values of compact and normal ring spun did not show any correlation. This once again confirms that Uster hairiness index and S3 values do not always go hand in hand.
Premier Electronic Tester
Premier Qualicenter, which is similar to Uster Tester, has an attachment to measure hairiness by hair count as well as Hairiness index method.
Speed of testing affects hairiness results[4,5]. Hairiness is found to reduce with test speed in SDL tester[5]. Direction of hairs, air drag and rubbing action against guides affect hairiness results. This could be one of the reasons for the different results obtained on different instruments. Humidity conditions in testing room as also conditioning time of yarn, affect hairiness. ASTM standard D5647-01 (1995) gives a standard method for measuring hairiness with photoelectric instruments. This will be helpful to minimize variations from laboratory to laboratory.
Online Measurement
Barco Profile Optical Measuring Unit, Uster Quantum Clearer and Loepfe Yarn Spectra and Lab Pack enable online measurement of yarn diameter and hairiness. The unit is fitted on clearer of winding unit and on rotor machine and sets aside packages, which give hairiness beyond a preset limit. Online measurement monitors the entire production and enables identification and prompt correction of defective units, which give high hairiness.
Weighing Technique
Difference in the mass of yarn before and after singeing[6] is used as a measure of hairiness. Flaw in this method is that a large amount of yarn has to be singed to get an accurate estimate. Moreover singeing does not fully remove fully projecting hairs particularly of shorter length.
روش‌های دیگر موجود که به تفکیک ذکر شده‌اند:Before instruments were developed, hairiness was measured by viewing the yarn under a microscope. Image of yarn is projected on a screen and number of protruding hairs and loops in a known length are counted. Length of protruding hairs is also measured with the help of micrometer eyepiece scale. From this, total length of hairs per unit length is determined. Pillay[1] projected the yarn on Projectina microscope and counted the number of protruding ends and loops in 10 mm length. Length of protruding fibres is measured by a curvimeter on a tracing of yarn image. Jedryka[2] took photographs of yarn image under microscope with a magnification of 50x. The boundary levels of yarn were marked. Four zones parallel to the boundary line were drawn on either side. The lines were equidistant with space between adjoining lines being kept as half the diameter of yarn. Hairiness is determined by the number of intersections the fibre makes with the lines marking the zone on either side. This method gives the hairiness as per the length of the hairs. About 50 to 100 yarn samples are examined from which average hairiness is determined.
Major difficulty in microscopic methods is in identifying the boundary of yarn. Looped fibres, wild fibres, low twisted portions, variation in yarn diameter and cross-section smudge the boundary. High variation in hairiness is found both within and between bobbins and as a result, large number of yarn specimens has to be examined to get a fairly reliable estimate. This makes the method laborious and time consuming.
Photoelectric Method
Several instruments are available for measurement of hairiness based on photoelectric method.
Shirley-Atlas Hairiness Tester
A measuring head consisting of a photocell placed close to the yarn counts the number of interruptions made by the protruding hairs to an LCD beam. The measuring head is infinitely adjustable from 1 to 10 mm from the surface of yarn. This enables measurement of hairiness as per the length of hairs. Nip rollers at 50 to 300 m/min drive yarn by an electronic variable speed drive. Latest version is operated by a PC. Continuous chart of hairiness can also be obtained through a recorder or printer. A portable battery operated model is available for online measurement of hairiness with a standard measuring head of 3 mm. Portable model will enable detection of spindles giving high hairiness.
Zweigle Hairiness Tester
This also uses a measuring head with a photocell and a laser light source. The instrument measures hairiness of 9 length zones from 1 to 12 or 15 mm fibre length in a single run of the yarn and produces a running chart of hairiness. Faults of a periodic nature can be detected. . The equipment is controlled by a PC, which carries out statistical analysis of the results. There is a facility for checking and matching all the optical channels with the reference value set ex works. Calibration with the yarn that has been checked on a master Hairiness tester is also possible. The above facilities improve reproducibility of results. An automatic bobbin changer up to 24 bobbins is available which makes the instrument fully automatic. Most of the research work on hairiness is based on tests on this instrument.
Meiners Dell Hairiness Tester
The instrument measures simultaneously hairiness of hair lengths from 1 to 10 mm in steps of 1 mm. A single run of the yarn gives hairiness for all lengths at a selected speed. A portable model is also available which enables online measurement of hairiness.
Changling Hairiness Tester
This uses a laser light source and a sensitive integrated photocell for measuring number of projecting hairs. Measurements of hair number for lengths from 1 to 9 mm are possible.
Apart from estimates of number of hairs, length-wise, another parameter that is commonly used is S3 value, which indicates the number of fibres, which protrude beyond 3 mm length.
Uster Tester
Uster Evenness Tester has a hairiness attachment. Measuring field consists of homogenous rays of parallel light from an infrared light source. Scattered light from the protruding hairs of yarn, placed in this field, reach an optical sensor, which converts it into an electronic signal. The body of yarn itself is dark as it is not transparent and so does not contribute to the measurement. The protruding fibres are bright and reflected light from these fibres alone contributes to measurement. Hairiness thus measured is an estimate of total length of protruding fibres in a cm length and is termed as Hairiness index. Hairiness index of 4 means that the total protruding length of hairs in 1 cm length is 4 cm.
Uster has been publishing periodically Uster standards for hairiness based on survey of mills worldwide. While this method has the merit that it gives a single index to characterise the hairiness, it has the drawback that it does not provide information on long length and short length hairs separately. Thus two yarns may have the same hairiness index but one may have more long hairs and fewer short hairs than other. Since long hairs are more objectionable than short hairs, information on the level of hairs as per their length will be more useful. Uster tester further gives coefficient of hairiness over measured lengths 1 cm (normal) 10, 100, 300, 1000, 5000 cm or in other words variance length curve of hairiness. Presence of periodicity in hairiness can also be determined by spectrogram of hairiness.
While some studies have shown a good correlation between hairiness by Shirley hairiness tester and Uster tester[3], others have found little association[4]. While Uster hairiness index is based on all hair lengths, S3 is based on hairs 3 mm and longer. So these two measures will correlate well only when number of hairs vs hair length relation is similar. Good correlation exits between Uster hairiness index of compact and normal ring spun yarns spun from a number of cottons. But Zweigle hairiness S3 values of compact and normal ring spun did not show any correlation. This once again confirms that Uster hairiness index and S3 values do not always go hand in hand.
Premier Electronic Tester
Premier Qualicenter, which is similar to Uster Tester, has an attachment to measure hairiness by hair count as well as Hairiness index method.
Speed of testing affects hairiness results[4,5]. Hairiness is found to reduce with test speed in SDL tester[5]. Direction of hairs, air drag and rubbing action against guides affect hairiness results. This could be one of the reasons for the different results obtained on different instruments. Humidity conditions in testing room as also conditioning time of yarn, affect hairiness. ASTM standard D5647-01 (1995) gives a standard method for measuring hairiness with photoelectric instruments. This will be helpful to minimize variations from laboratory to laboratory.
Online Measurement
Barco Profile Optical Measuring Unit, Uster Quantum Clearer and Loepfe Yarn Spectra and Lab Pack enable online measurement of yarn diameter and hairiness. The unit is fitted on clearer of winding unit and on rotor machine and sets aside packages, which give hairiness beyond a preset limit. Online measurement monitors the entire production and enables identification and prompt correction of defective units, which give high hairiness.
Weighing Technique
Difference in the mass of yarn before and after singeing[6] is used as a measure of hairiness. Flaw in this method is that a large amount of yarn has to be singed to get an accurate estimate. Moreover singeing does not fully remove fully projecting hairs particularly of shorter length.
روش قطبنده‌های متقاطع:
در این روش نور به نخ تابانده شده که یک قسمت به بدنه‌ی نخ و قسمتی به الیاف بیرون زده برخورد می‌کنند. حال این نور پرتوهای شامل پرتوهای پلرایز شده و نشده هستند. سپس یک تحلیلگر که زاویه‌ی صفحه‌ی قطبش آن عمود بر زاویه‌ی تابش پرتو است، فقط به قسمت غیر قطبیده که همان اطلاعات شامل قسمت پرزینه است اجازه‌ی عبور می‌دهد. به این گونه اطلاعاتی از این قسمت به دست می‌آید. کالیبراسیون دستگاه توسط نخی با پرزینگی مشخص انجام می‌شود.
Hairiness measurement of textile yarns using crossed polarizers
Arun Anand,a_ Vani K. Chhaniwal, and C. S. Narayanamurthy
Photonics Laboratory, Applied Physics Department, Faculty of Technology and Engineering,
MS University of Baroda, Vadodara 390001, Gujarat, India
_Received 5 March 2005; accepted 23 May 2005; published online 23 June 2005_
REVIEW OF SCIENTIFIC INSTRUMENTS 76, 076104 _2005
Arun Anand,a_ Vani K. Chhaniwal, and C. S. Narayanamurthy
Photonics Laboratory, Applied Physics Department, Faculty of Technology and Engineering,
MS University of Baroda, Vadodara 390001, Gujarat, India
_Received 5 March 2005; accepted 23 May 2005; published online 23 June 2005_
REVIEW OF SCIENTIFIC INSTRUMENTS 76, 076104 _2005
روش سیگنال نوری چسبنده:
این روش در دو مقاله‌ی مجزا بحث شده است که خلاصه‌ی آن به شرح زیر است:
دستگاه دو قسمت دارد، یکی قسمت نوری برای عکس برداری و دیگری قسمت الکترونیکی جهت تبدیل این سیگنال نوری به سیگنال ولتاژی متناسب با آن. البته از یک نرم‌افزار کامپیوتری نیز به منظور تحلیل استفاده می‌شود.
Optical yarn hairiness measurement system
Vitor H.Caravalho, Paulo J . Cardoso, Rosa M.
1-4244-0865-2/07/$20.00 ©2007 IEEE.
Vitor H.Caravalho, Paulo J . Cardoso, Rosa M.
1-4244-0865-2/07/$20.00 ©2007 IEEE.
روش آرایه‌ی خطی CMOS:
این روش در حقیقت تکمیل شده‌ی روش قبلی است که به طور کامل کامپیوترایز شده و نتایج آن در مجله‌ی ذیل آمده است:
Yarn hairiness and diameter characterization using a CMOS line array
Vitor Carvalho a,*, Michael Belsley b,1, Rosa M. Vasconcelos c,2, Filomena O. Soares a,3
a DEI, UM, Azurém, Guimarمes, Portugal
b DF, UM, Gualtar, Braga, Portugal
c DET, UM, Azurém, Guimarمes, Portugal
journal homepage: www.elsevier.com/ locate/measurement [Measurement 41 (2008) 1077–1092]
Vitor Carvalho a,*, Michael Belsley b,1, Rosa M. Vasconcelos c,2, Filomena O. Soares a,3
a DEI, UM, Azurém, Guimarمes, Portugal
b DF, UM, Gualtar, Braga, Portugal
c DET, UM, Azurém, Guimarمes, Portugal
journal homepage: www.elsevier.com/ locate/measurement [Measurement 41 (2008) 1077–1092]
روش آنالیز تصاویر دیجیتال:
این روش در مقاله‌ی زیر بحث شده است که متأسفانه به اصل مقاله دسترسی پیدا نکردم و فقط خلاصه‌ی آن (البته همراه با اطلاعات جانبی‌اش) را آورده‌ام.
Simulation of photo sensor-based hairiness measurement using digital image analysis
Authors: Yasar A. Ozkayaa; Memis Acara; Mike R. Jacksona
Affiliation: a School of Mechanical and Manufacturing Engineering, Loughborough University, Loughborough, Leics, UK
Published in: Journal of the Textile Institute, Volume 99, Issue 2 April 2008 , pages 93 – 100Authors: Yasar A. Ozkayaa; Memis Acara; Mike R. Jacksona
Affiliation: a School of Mechanical and Manufacturing Engineering, Loughborough University, Loughborough, Leics, UK
Abstract
The hair-counting technique using photo sensors is a common method to measure the hairiness of the yarns. However, the literature recognizes some deficiencies of the technique regarding the sensor limitations. This paper describes a computer vision approach to simulate the photo sensors and to investigate the parameters effecting the hairiness measurement when using these sensors. An algorithm developed to simulate the photo sensor signals is explained. The effects of sensor resolution, signal threshold level and selection of zero reference positions from the core are investigated. The correlation between the measurements taken from two different sides of the yarn core is also examined. Twenty yarn samples are tested using a Zweigle G565 hairiness tester, and the results are compared with the hairiness measurements from the simulated photo sensor system using digital images.
Keywords: Yarn hairiness; digital image analysis; sensor resolution
The hair-counting technique using photo sensors is a common method to measure the hairiness of the yarns. However, the literature recognizes some deficiencies of the technique regarding the sensor limitations. This paper describes a computer vision approach to simulate the photo sensors and to investigate the parameters effecting the hairiness measurement when using these sensors. An algorithm developed to simulate the photo sensor signals is explained. The effects of sensor resolution, signal threshold level and selection of zero reference positions from the core are investigated. The correlation between the measurements taken from two different sides of the yarn core is also examined. Twenty yarn samples are tested using a Zweigle G565 hairiness tester, and the results are compared with the hairiness measurements from the simulated photo sensor system using digital images.
Keywords: Yarn hairiness; digital image analysis; sensor resolution
