Non destructive testing of fabric weight in the weaving process Y.-S. Gloy, T. Gries and G. Spies 13th International Symposium on Nondestructive Characterization of Materials

Content  Institut für Textiltechnik der RWTH Aachen University  Testing of fabric weight in the weaving process  Introduction  Capacitive sensor  X-ray sensor  Closed-loop control  Validation  Summary and outlook

Content  Institut für Textiltechnik der RWTH Aachen University  Testing of fabric weight in the weaving process  Introduction  Capacitive sensor  X-ray sensor  Closed-loop control  Validation  Summary and outlook

 Students in 126 courses of study  340 Institutes with 480 professorships  6900 Employees (thereof 65% scientists)  750 Mio € Total budget, thereof:  320 Mio € Third party funding RWTH Aachen University 4 Source: RWTH Aachen University, Photos Peter Winandy

New form of cooperation between industry and university:  15 relevant clusters  Exchange of research results, employees, further resources  Biggest european technology campus  Ca. 2 Bill € investment till 2020 Source: rha reicher haase + associierte ITA RWTH Aachen Campus 5

The unique position of ITA 6 application fields mobility building & living health energy Comprehensive textile process chains technology and competence fields raw materials: natural fibers, polymers,... semi-finished textiles & products

Budget: ca. 14,3 Mio. € Staff:  85 Scientists  55 Service personnel  190 Graduate research assistants  50 Students majoring in textile technology each year Research and development  Publicity and third party funded research  Academic and industrial education Development and transfer  Direct industrial research  Further education partially public public Strictly confidential Fundamental Research ca. 30% Industrial Funding ca. 31% Industry-Related Public Funding ca. 35% Subsidy ca. 4% Institut für Textiltechnik der RWTH Aachen University 7

Content  Institut für Textiltechnik of RWTH Aachen University  Testing of fabric weight in the weaving process  Introduction  Capacitive sensor  X-ray sensor  Closed-loop control  Validation  Summary and outlook

Woven fabrics  Rectangular crossing of warp and weft Applications  Clothing  Technical textiles e.g.  Airbags, Parachutes, Composites Weaving machines  Standard machine speed up to 1000 rpm  Weft insertion efficiency of 2000 m/min  machines produced worldwide (2011) Fabric weight important quality criteria 3D-Fabric; Source: ITA Weaving Maschine; Source: Picanol nv, Ieper, Belgium Airbag; Source: ITA 9

Principle of a weaving machine Warp beam Back rest Warp stop motion Shed Reed Fabric take- off Fabric beam Weft Warp Fabric Direction of production Principle of a weaving machine; Source: ITA 10

Content  Institut für Textiltechnik of RWTH Aachen University  Testing of fabric weight in the weaving process  Introduction  Capacitive sensor  X-ray sensor  Closed-loop control  Validation  Summary and outlook

Capacitive sensor Capacity of a parallel plate capacitor is determined by Where C = capacity; ε 0 = x 10-12, ε r = dielectric relative constant, S = area and d = distance According to Carvalho et al. a relationship is established between the capacity and a passing yarn mass Capacitive sensor ; Source: ITA Principle of a capacitive sensor 12

Installation of capacitive sensor Instalation of capacitive sensor on a weaving machine; Source: ITA 13

Validation of capacitive sensor 14

Content  Institut für Textiltechnik of RWTH Aachen University  Testing of fabric weight in the weaving process  Introduction  Capacitive sensor  X-ray sensor  Closed-loop control  Validation  Summary and outlook

X-ray sensor Principle of an X-Ray sensor, Source: ITA with Radiometric absorption according to Beer-Lambert law where I = Intensity of the beam, I 0 = original intensity of the beam, L = length of beam into the substance, e = Euler's number, about 2.718, µ = the attenuation coefficient ρ = the density, µ/ρ = the mass attenuation coefficient and ρL = the area density, m = total mass of the object and A = total area Sensor from BST ProControl Rengsdorf GmbH, Rengsdorf, Germany  Radiometric absorption system  Accelerating voltage < 5kV, can be used in Germany without approval  Measurements between 50 and 1000 g/m²  Resolution of 0,1 g/m² 16

Installation of X-ray sensor Installation of x-ray sensor on a weaving machine; Source: ITA 17

Comparison – X-Ray sensor vs. fabric weight (DIN EN 12127) Weaving machine running at 400 rpm 18

Content  Institut für Textiltechnik of RWTH Aachen University  Testing of fabric weight in the weaving process  Introduction  Capacitive sensor  X-ray sensor  Closed-loop control  Validation  Summary and outlook

Closed-loop control Due to dead time (depending on rpm and weft density) use of Smith Predictor PI Controller and prediction of plant without dead time Integration into loom via components form iba AG, Fürth, Germany components Smith Predictor control of fabric weight; Source: ITA F W = Fabric weight G F = transfer element of signal to fabric weight G R = transfer element of PI Controller G S = transfer element of sensor G W = transfer element of weaving machine G T = transfer element of dead time = transfer element of model of the plant 20

Step response Step in weft density 21 Sensor voltage U S [V]

Content  Institut für Textiltechnik of RWTH Aachen University  Testing of fabric weight in the weaving process  Introduction  Capacitive sensor  X-ray sensor  Closed-loop control  Validation  Summary and outlook

Field trial within WeyermannTechnical Textiles GmbH & Co. KG, Wegberg, Germany Accuracy of fabric control less 3 % System accepted by weaving mill workers Validation of Smith Predictor Simulation Measurement Conventional controller Actuating variable Smith Predictor ΔF W / ΔF W desired 23

Content  Institut für Textiltechnik of RWTH Aachen University  Testing of fabric weight in the weaving process  Introduction  Capacitive sensor  X-ray sensor  Closed-loop control  Validation  Summary and outlook

Summary and outlook Summary  Capacitive sensor not suitable  X-Ray sensor can be used to monitor fabric weight  Smith predictor as control loop for field test Outlook  Integration of further sensor  Camera system to detect weft errors and weft density developed at ITA  Transfer to further textile processes 25

Thank you for your attention The authors would like to thank the German Research Foundation DFG for their support of the depicted research within the Cluster of Excellence "Integrative Production Technology for High-Wage Countries“

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