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Sensors
- AMORAN
- special scanners:
  for glass tubes
  for image acquisition
  seam detector 
  Retro-Scanner
  Fibre-Positions
  Fibre-Diameters
- FIPS
- Scratch Detector

OPOS

 

 

Fiber deflection

Overview

Melt spinning processes

  • Input of the melt spinning process is a homogeneous polymer melt either from an extruder or polycondensation stages.
  • Filaments are produced by pressing this melt through the spinneret.
  • Below the spinneret the fibre formation starts. The polymer beams are cooled down to fibres. The material properties of the filaments depend mainly on tension and the quench air flow.
  • The fibre formation zone ends in the quench cabinet.
  • Below the quench cabinet are stages for further manipulation resp. the winder.

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.

Fibre deflection

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:

with:

 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.

If you are interested in further information, a demonstration, an adaptation of this sensor or a development of a solution of your measurement problem, please contact:

mail@opos.de or:

OPOS Optical On Line Sensors
Hertzstr. 164b
D-76187 Karlsruhe / Germany
Tel +49 (721) 971305-0
Fax +49 (721) 971305-1

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