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
Motivation and Objectives
The flow is steady
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
HIPS: DOW Styron 478 (MFI=6)
BASF 496N (MFI=2.8)
Pseudoplacticity included Viscoelastic effects neglected.
Extruder Die Mounting Plate
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.
Pre-land inlet geometry fixed
Die land: uniform passage
Free surface exit matches target extrudate: fixed
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.
Velocity Magnitude (m/s)
Extrudate Free Surface (Target Profile)
Direct Extrusion simulation result with Styron 478 and Styron 496
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.
Stacked Plate Design: Passage matches target profile, no taper along flow direction.
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
Side wall shrinkage: 3% – 6%
Air gap = shrinkage
Calibrated mass balance
Calibration rearranges mass balance
Air cushion mass balance
P@3 kg/hr (most uniform thickness) is 6% thinner than target: draw down and shrinkage affects.
Order of magnitude difference: can testing results be generalized?
Temperature data input to transient 1-D simulation to iterate for effective heat transfer between extrudate and calibrator.
Boundary Conditions for 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 at Three Critical Points