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The Forming and Densification of Fibre Mats in Twin-Wire Formers: Modelling

Vinicius Lobosco, Bo Norman & Sören Östlund. The Forming and Densification of Fibre Mats in Twin-Wire Formers: Modelling. Outline. Background on forming Model Results Conclusion Future Work. Schematic Papermachine. A. Flaks. A Modern Forming Section. Blades improve formation
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Vinicius Lobosco, Bo Norman & Sören ÖstlundThe Forming and Densification of Fibre Mats in Twin-Wire Formers: ModellingOutline
  • Background on forming
  • Model
  • Results
  • Conclusion
  • Future Work
  • Schematic PapermachineA. FlaksA Modern Forming Section
  • Blades improve formation
  • Mats start on the roll
  • Norman & FellersFiltrationThickeningDewatering MechanismsParker, 1972Outline
  • Background on forming
  • Model
  • Results
  • Conclusion
  • Future Work
  • Present Available Models
  • Incompressible
  • Zhao & Kerekes
  • Roshanzamir et al.
  • Holmqvist
  • Elastic
  • Martinez
  • Zahrai et al.
  • Experimental Material Behaviour
  • Vomhoff & Schmidt
  • Permanent deformation
  • Hysteresis
  • Mathematical Model
  • Balance Equations:
  • Mass;
  • Momentum
  • Transfer Equations
  • Constitutive Equations
  • Assumptions
  • Continuum
  • Intertial effect neglected
  • Wire gives no resistance
  • Symmetry
  • Darcyan flow
  • No interface resistance
  • Mathematical Model 2
  • Convective-diffusive time-dependent equation
  • Finite Element Method (FEM)
  • Variation = Convection + DiffusionOutline
  • Background on forming
  • Model
  • Results
  • Conclusion
  • Future Work
  • Results 1
  • Filtration
  • Dryness
  • Unbeaten Kraft pulp – CSF 718
  • 10 kPa – 20 ms
  • Results 2
  • Dryness
  • Beaten kraft pulp CSF 598
  • 10 kPa – 20 ms
  • Results 3
  • Thickning
  • Blade forming
  • Three haversinus pulses 15 kPa 2 ms with 2 ms interval
  • Results 4
  • Contours of Structural stress
  • Results 5
  • Material response from the different elements and the experimental data (Vomhoff & Schmidt)
  • Results 6
  • Diminishing returns
  • Average solids content vs. applied stress
  • No improvement after 15 kPa
  • Average final solids contentConclusions
  • Demonstrates considerable dryness gradient effects.
  • Demontrates dryness relaxation effects.
  • Needs more data on unloading of webs.
  • Available to the industry.
  • Will be of large interest in modelling of twin-wire roll and blade forming.
  • Future Work
  • Numerical
  • Streamline diffusion
  • Moving Finite Elements (Yi Liu – C4)
  • Physical Model
  • Hysteresis operator
  • Wire and interface resistance
  • Generalisation
  • Couple with Holmqvist's blade pressure model
  • Validate
  • Filtration and papermachine (e.g. Euro-FEX)
  • Acknowledgements
  • CPDC for the funds that made this project possible
  • Hannes Vomhoff for making his experimental data available.
  • Raul Tempone (NADA – KTH) for the support regarding the numerical method
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