Transcript Extrusion Simulation and Design of Dies

OPTIMIZATION OF A PROFILEEXTRUSION DIE DESIGN USING
INVERSE CFD SIMULATION
Fluent UGM 2004
June 8 -10
By
Prof. M. Kostic, Ph.D, P.E.
Srinivasa Rao Vaddiraju, M.S.
Department of Mechanical Engineering,
NORTHERN ILLINOIS UNIVERSITY
www.kostic.niu.edu/extrusion
Introduction
Twin-screw extrusion line
Fermi National Accelerator Laboratory (FNAL)
Northern Illinois Center for Accelerator and Detecto
Development (NICADD)
Department of Mechanical Engineering
Cast plastic scintillator - $40/kg
Extruded plastic scintillator - $10/kg
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Profile Extrusion Line at FNAL
Berstorff 40-mm diameter, 1.36 m long,
twin-screw extruder
Two K-Tron automated feeders
Conair downstream equipment
Novatec compressed-nitrogen drier
Dryer
Polymer
pellets Dopants
Feeding
Hopper
Breaker
plate
Die
Extruder
Gear
pump
Cooling
Haul-off
Cutter
Calibrator
Measurement
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Objectives
Effective die design strategy
Die swell and optimum die profile-shape
Mass flow balance
Flow and heat transfer Simulation
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
POLYFLOW
Finite-element CFD code
Predict three-dimensional free surfaces
Inverse extrusion capability
Strong non-linearities
Evolution procedure
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Flowchart for Numerical Simulation
1. Draw the geometry using a CAD software
2. Mesh the geometry
3. Specify Polymer properties and
boundary conditions
Modify the
mesh
4. Specify remeshing technique, solver
method and evolution parameters
Modify remeshing
techniques, solver
methods and/or
evolution parameters
No
5. Solver solves the conservation equations
using the specified data and boundary
conditions
6.Is the
solution
converged?
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Yes
Stop
General Assumptions
The flow is steady
and incompressible
Body forces and Inertia effects are
negligible in comparison with
viscous and pressure forces.
Specific heat at constant pressure, Cp, and
thermal conductivity, k, are constant
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Material Data
Styron 663, with Scintillator dopant additives
Measured by, Datapoint Labs, NY
Carreau-Yasuda Law for viscosity data:
η0 = 36,580 Pa-s
η∞ = 0 Pa-s
λ = 0.902
a = 0.585
n = 0.267
ρ = 1040 Kg/m3
Cp = 1200 J/Kg-K
k = 0.12307 W/m-K
β = 0.5e-5 m/m-K
NOTE: Viscoelastic properties were neglected in our simulation
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Styron viscosity data, with and
without Scintillator dopants
Viscosity (Pa-s)
106
η – Styron 663
ηd– Doped Styron 663
105
180 0C
200 0C
104
220 0C
103
102 -2
10
10-1
100
101
Shear Rate (1/s)
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102
103
Required Extrudate profile
0.11
0.5
10.0
All dimensions are in cm
Rectangular cross section of 10 cm  0.5 cm
with ten equally spaced centerline circular
holes of 1.1 mm diameter, to accommodate
wavelength-shifting optical fiber.
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Exploded view of the extrusion die
Melt pump
adapter
Adapter 1
Adapter 2
Preland
Dieland
Melt flow
direction
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Half domain of the extrusion die
Melt Pump Adapter,
Adapter 1 and Adapter 2
Spider
Die land
Free Surface
Melt flow
direction
Die lip
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Simulation domain with
boundary conditions
1. Inlet (Fully Developed Flow)
2. Wall (Vn = 0, Vs = 0)
3. Symmetry (Vn = 0, Fs = 0)
4. Free Surface (Fs = 0, Fn = 0, V.n = 0)
1
5. Outlet (Fn = 0, Vs = 0)
2
4
Melt flow
direction
3
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5
Finite element 3-D domain
and die-lip mesh
19,479 elements
Skewness < 0.5
Melt flow
direction
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Half domain of the extrusion die
(without free surface) and division of
outlet into 10 areas
d2
out8
out10 out9
out7
d0
d1
Melt flow
direction
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out6
out5 out4
out3
out2
out1
Percentage of Mass flow rate in
different exit segments
Out10
Outlet
Out9
Out8
Case 8
Out7
Case 7
Out6
Case 6
Case 5
Out5
Case 4
Case 3
Out4
Case 2
Case 1
Out3
Out2
Out1
0.00%
5.00%
10.00%
% of mass flow rate
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Computation time
Windows XP
2.52 GHz Processor
1 GB RAM
One hour of CPU time
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Contours of static pressure
Melt flow
direction
Die lip
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Contours of Velocity magnitude
Velocity
Magnitude
(m/s)
X-Coordinate (m)
Melt flow
direction
Die lip
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Contours of temperature
distribution
Melt flow
direction
Die lip
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Contours of Shear rate and Viscosity
Melt flow
direction
Die lip
Shear rate
Melt flow
direction
Viscosity
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Simulated die and required
extrudate profiles
1
0
1
24
24.5
25
25.5
26
1
26.5
-1
0
0
4
5
6
44
7
44.5
45
45.5
46
46.5
-1
-1
3
0
0
10
20
30
40
-3
50
1
1
Simulated Die
Required Extrudate
0
14
14.5
15
15.5
16
0
34
16.5
-1
-1
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35
36
37
Percentage of mass flow rate for
designed and balanced die
Outlet
Designed Die
Balanced Die
Out10
Out9
Out8
Out7
Out6
Out5
Out4
Out3
Out2
Out1
0.00%
5.00%
% of Mass Flow Rate
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10.00%
Conclusions
Optimum dimensions of the die
More balanced flow
Flow in the die - no re-circulation
regions.
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Recommendations for future
improvements
Polymer viscoelastic properties
Include flow, cooling, solidification and
vacuuming in and after the calibrator
Radiation effects for free surface flow
Pulling force at the end of the free surface
Pressure of the compressed air
More non-uniform mesh
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ACKNOWLEDGEMENTS
NICADD (Northern Illinois Centre for
Accelerator and Detector Development),
NIU
Fermi National Accelerator Laboratory,
Batavia, IL
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QUESTIONS ?
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Contact Information
mailto: [email protected]
www.kostic.niu.edu
mailto: [email protected]
www.vaddiraju.com
Department of Mechanical Engineering
NORTHERN ILLINOIS UNIVERSITY
www.kostic.niu.edu/extrusion