2005 CFD Summit The Meeting of the Minds in Flow Modeling June 7-9, 2005 Dearborn, Michigan. Design Improvement of a U-Profile Extrusion Die Using Inverse CFD Simulation. M. Kostic , Northern Illinois University Srinivasa Rao Vaddiraju , Northern Illinois University
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2005 CFD SummitThe Meeting of the Minds in Flow ModelingJune 7-9, 2005Dearborn, Michigan
Design Improvement of a U-Profile Extrusion Die Using Inverse CFD Simulation
M. Kostic, Northern Illinois University
Srinivasa Rao Vaddiraju, Northern Illinois University
Louis G. Reifschneider, Illinois State University
Polyflow Inverse Extrusion SimulationGeneral Assumptions :
Body forces and Inertia effects are negligible in comparison with viscous and pressure forces.
Specific heat at constant pressure, Cp, andthermal conductivity, k, are assumed constant
(2.54 mm thick)
Required Extrudate Profile
2Viscosity Model: Cross-WLF
HIPS: DOW Styron 478 (MFI=6)
BASF 496N (MFI=2.8)
Pseudoplacticity included Viscoelastic effects neglected.
Extruder U-Profile Adapter Plate
Exploded View of Die Assembly
Melt Flow direction
Simulation determines Pre-Land & Die Land plates
16,592 hex. elem.
1 GB RAM,
@ 2.39 GHz,
Isothermal analysis required 552 minutes CPU.Finite Element Mesh
Die land: uniform passage
Free surface exit matches target extrudate: fixedBoundary Conditions (symmetry)
No slip at die surface
Inlet: fully developed flow
Zero traction &
No normal velocity
Exit: Zero normal stress & Plug flow
Profile of the inlet to the pre-land plate was determined by a series of trial and error extrusion simulations to insure a balanced mass flow exiting the die.
Outlet 6Flow simulation only within the die
Pressure (Pa) a series of trial and error extrusion simulations to insure a balanced mass flow exiting the die.
Velocity Magnitude (m/s)Representative Pressure and Velocity Results
Die Land a series of trial and error extrusion simulations to insure a balanced mass flow exiting the die.
Die LandInverse Extrusion simulation results with Pre-land and Die Land Contours
Extrudate Free Surface (Target Profile)
478 direct extrusion extrudate profile
496 direct extrusion extrudate profile
Target extrudate profile
As expected the free surface outlet profile from the results of direct extrusion with Styron 478 is very close to the target profile we used in inverse extrusion CFD simulation.
Vacuum Lines Styron 496
Stacked Plate Design: Passage matches target profile, no taper along flow direction.
Vacuum LinesVacuum Calibrator Design
Cut Off Styron 496
Schematic of U-Profile Extrusion Line with Data Acquisition
Upper Exit IR
Lower Exit IR
Exit Top IR
Exit Bottom IR
Exit Bottom IR
Corner pulling away Styron 496
Side wall shrinkage: 3% – 6%
Air gap = shrinkageProduct Shrinkage at Calibrator Exit
Fredette Styron 496
Order of magnitude difference: can testing results be generalized?HeatTransferData
Temperature data input to transient 1-D simulation to iterate for effective heat transfer between extrudate and calibrator.
Boundary Conditions Styron 496for Extrudate Cooling Simulation
L = 50 mm
Tinlet = 505 K
= 10 W/m2K + 15 W/m2K
= 295 K
L = 95
= 303 K
= 175 W/m
= 225 W/m
= 297 K
V = 6.3 mm/s
Evolution of Temperature Contours as Extrudate Passes Through Calibrator
150 - 200
150 - 200
100 - 150
100 - 150
50 - 100
Black area solidified
Outline of full profile shown
Center-line Temperature History Through Calibratorat Three Critical Points