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Quench air flow and the fibre tension determine the ratio of crystalline to amorphous fraction of the polymer material and the orientation of the molecule chains in the amorphous regions. These properties are mainly influencing the mechanical properties and the dyeability of the produced yarns.
By the quench air flow, forces on the fibres are applied. Depending on the profiles (over the distance to spinneret) of fibre diameter, fibre speed and quench air velocity, the fibres are more or less deflected. The fibre deflection is e. g. described by the following differential equation:
|Y: fibre deflection||X: distance from spinneret|
|Q: mass throughput||V: fibre velocity|
|F: force||cw: coefficient of air-friction|
|r*:density of quench air||VY: quench air velocity|
In combination with a model of fibre formation this equation allows 2d- calculations of fibre formation. The boundary values are given by the spinneret position (X=0) and the position of the first yarn-guide. The figure shows example calculations for a single filament in industrial spinning processes with different quench air velocities and demonstrates further the influence of the coefficient of air friction. The fibre position scanner allows precise measurements of the deflection of all filaments in a bundle and thus precise checks of models of fibre formation.
For industrial purposes or applications, where the mean deflection of the fibres is sufficient, the Filament-Bundle-Position-Sensor is a proven tool. The figure below shows profile measurements of the average deflection of a fibre bundle, taken by this sensor.
In addition FIPS provides measurements of the light intensity scattered at the fibres (see the profile measurements on the figure below). This measurement is depends mainly on the fibre diameter, the density and pigmentation. For constant cristallinity and pigmentation, it allows the calculation of the average fibre diameter.
OPOS Optical On Line Sensors
D-76187 Karlsruhe / Germany
Tel +49 (721) 971305-0
Fax +49 (721) 971305-1
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