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«Advantages of Green Sand Molding Process Using Aeration Technology»
«Yaş Kalıplama Tekniğinde Havalandırma Teknolojisinin Faydaları»
Hiroyasu Makino (Sintokogio, Evren İth. İhr.)
3.Oturum: Döküm Teknolojileri Demir - Çelik 3rd Session: Casting Technologies Iron - Steel
Oturum Başkanı/Session Chairman: Seyfi Değirmenci (Componenta Döküm. Tic. San. A.Ş.)
Oturumlarda yer alan sunumlar 15 Eylül 2014 Pazartesi tarihinde kongre web sayfasına (kongre.tudoksad.org.tr) yüklenecektir.
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ADVANTAGES OF GREEN SAND
MOLDING PROCESS
USING AERATION TECHNOLOGY
Dr. Hiroyasu MAKINO, Shuichi TSUZUKI, Minoru HIRATA
SINTOKOGIO, LTD., Japan
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CONTENT
1 AERATION TECHNOLOGY
- comparison of molding technology
- computer simulation and experiment for sand molding
- sand detection sensor
2 SAND MOLD & CASTING PROPERTY WITH AERATED SAND
- friability
- casting surface
3 CONCLUSION
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Mission of Sand Molding Technology
1) Good sand filling
2) Good casting
3) Environmentally-friendly
Aeration sand filling
World casting production in 2012 exceeded 100 million tons.
Over 80 % of production was iron castings and made with sand molds.
Image of Aeration Sand Filling 4
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Comparison of Green Sand Molding Technology
air-flow + squeeze blow + squeeze
blow(0.3MPa)
compacted
difference
of density
free fall (louver hopper )
aeration + squeeze
aeration(0.1MPa)
sand cut
difficult to sufficiently fill
air air
air
air
Developed
smooth fill and
uniform density
tight-flask flask-less tight-flask & flask-less
Conventional Molding
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Comparison Movie of Aeration, Blow and Gravity
Sand Filling Process
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Actual Production Molding Machine
Pattern carrier
Flask(700x900x300)
Filling flame
Sand tank
Slide gate
Aeration filter
air inlet
air inlet
air inlet
air outlet 700
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Test Pattern for Sand Filling Experiment
•Cavity(pocket) depth = 50mm
•With vent hole 30
700(flask size)
10
0
4X50=200
90
0(f
lask s
ize
)
510
10
0
Ø 10
Ø 30
Ø 20
30
no
zzle
no
zzle
X
Y
Sand Filling Process
- Gravity free fall
(Louver hopper)
- Blow (0.3MPa)
- Aeration (0.1MPa)
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Experimental Results of Sand Filling for Small Pocket
50
150
250
50
150
250
0
200
400
600
800
1000
1200
bulk
densi
ty ,k
g/m
3
Y ,mm
X ,mm
Blow : 0.3MPa Gravity free fall
(Louver hopper)
50
150
250
50
150
250
0
200
400
600
800
1000
1200
bulk
densi
ty ,k
g/m
3
Y ,mm
X ,mm
Ø 10 Ø 30 Ø 20
730 kg/m3
(0.73 g/cm3)
Ø 10
Ø 30 Ø 20
Bulk density : 1,000 kg/m3 before molding at CB40%
1040kg/m3
(1.04g/cm3)
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Experimental Results of Sand Filling for Small Pocket
Aeration : 0.1MPa Aeration : 0.15MPa
50
150
250
50
150
250
0
200
400
600
800
1000
1200
bulk
densi
ty ,k
g/m
3
Y ,mm
X ,mm 50
150
250
50
150
250
0
200
400
600
800
1000
1200
bulk
densi
ty ,k
g/m
3Y ,mm
X ,mm
Ø 10 Ø 30 Ø 20 950kg/m3
(0.95g/cm3) 890kg/m3
(0.89g/cm3)
High pressure filling of green sand has an energy loss and an opposite
effect for filling into the small pocket.
Ø 10
Ø 30 Ø 20
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Computer Simulation of Sand Filling
•Mathematical model is based on euler two-phase continuous theory with Gidaspow’s typical kinetic theory and Sinclair’s viscosity theory.
•Air flow and sand flow is treated respectively
0
ggggg V
t
gsgggggggg VVVVV
t
Continuity equation for gas(air) phase
Momentum equation for gas(air) phase
Air
Sand Continuity equation for solid(sand) phase
Momentum equation for solid(sand) phase
0
sssss V
t
gVVVVVt
sssgssssssss
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Computer Simulation for Squeeze
silica sand
bentonite/water
air
•Commercial FEM software ABAQUS is applied. •The nonlinear elastic material model is used for squeeze simulation.
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Geometrical Model of Flask-less Molding
A) Integrated geometrical model B) Symmetrical half part
Flask size: 608x510x260mm Observing sand filling behavior
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60
8
510 260
Sleeve
Ø70 x H110 mm
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Simulation and Experimental Results
for Aeration Sand Filling Process
0.05s 0.15s 0.25s 0.45s 0.80s
Experimental result
Simulation result
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Simulation and Experimental Results
for Squeeze Process
Experimental
result
Simulation
result
Parting plane Cross section
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SAND DETECTION SENSOR FOR SAND FILLING
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Aeration Squeeze Schematic Illustration
of Sensor
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SAND DETECTION SENSOR FOR SAND FILLING
1
2
3
Sleeve : Ø70 x H70 mm
1 2 3
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SAND DETECTION SENSOR FOR SAND FILLING
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The behavior of aeration sand filling is not
much affected by pattern shape.
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CONTENT
1 AERATION TECHNOLOGY
- comparison of molding technology
- computer simulation and experiment for sand molding
- sand detection sensor
2 SAND MOLD & CASTING PROPERTY WITH AERATED SAND
- friability
- casting surface
3 CONCLUSION
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Schematic Illustration of Fundamental Aeration Sand Filling
Green Sand Tank
Aeration Filter
Air Inlet Air Inlet
Air Inlet
Air Inlet
Air Outlet
Air Outlet
Pressure Sensors
AFS Specimen Tubes
Half-Section Sleeve
Ø60mm x H120mm
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Measured Properties of Green Sand
AFS Test Aeration Filling Gravity Filling
Compactability (%) 30
(0.2) 35
(0.2) 40
(1.0) 30
(1.0) 35
(1.5) 40
(1.0)
Bulk Density (g/cc) 0.99
(0.01) 0.99
(0.01) 0.89
(0.02) 0.98
(0.02) 0.89
(0.01) 0.88
(0.04)
Moisture content (%) 2.5
(0.02) 2.5
(0.01) 2.5
(0.01) 1.9
(0.14) 2.5
(0.05) 2.7
(0.10)
Specimen weight (g) 160 (1.0)
158 (1.0)
158 (0.5)
158 (1.0)
158 (1.5)
152 (0.5)
Permeability (#) 220 (1.0)
223 (1.5)
228 (1.2)
228 (2.0)
233 (1.0)
261 (1.0)
Splitting Strength (psi) 3.4
(0.12) 5.4
(0.20) 5.1
(0.10) 3.9
(0.05) 5.4
(0.10) 5.0
(0.09)
Compression Strength (psi) 17
(1.2) 24
(1.0) 25
(1.2) 21
(0.2) 24
(0.5) 24
(0.1)
Mold Hardness (#) 93
(1.5) 94
(1.0) 97
(0.5) 92
(1.0) 94
(1.2) 96
(1.1)
Friability (%) 9
(1.0) 7
(0.5) 5
(0.2) 31
(3.0) 17
(2.0) 10
(1.0)
Note : italicized number in parenthesis indicates standard deviations
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AFS Friability Test
Measures the abrasion characteristics of the sand
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Comparison of Casting Surface
Test Castings
Gravity Wedge Section Aeration Wedge Section
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Advantages of Aeration Technology Achieved Missions
1) Good sand filling
- especially for small pocket
2) Good casting
- because of low friability and strong mold
3) Environmentally-friendly
- low air & energy consumption, low noise
because of low air pressure
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Molding Machine Using Aeration Technology
4) flask-less
- small flask size
(450x350)
1) tight flask 2) flask-less
- two station
3) flask-less
- single station
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CONCLUSION
Aeration sand filling technology in green sand molding process is evaluated
from the view of sand filling process and mold properties after sand filling.
The results are summarized as follows.
1) Aeration sand filling and squeeze are numerically simulated. The
calculated result is in agreement with the experimental results. Through
these experiment and simulation, aeration sand filling is effective for
sleeve pattern and can make highly strong and uniformly dense mold by
lower air consumption.
2) The sand detection sensor can evaluate sand filling behavior. The
behavior of aeration sand filling is not much affected by pattern shape.
3) Friability by aeration sand filling is lower than that of conventional gravity
sand filling, especially in case of lower compactability. Therefore, aerated
green sand mold can reduce casting defects caused by green sand
property.
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ACKNOWLEDGMENT
The authors gratefully acknowledge to
Prof. WU Junjiao at Tsinghua University, China
for computer simulation of sand molding.
Dr. Hartmut Polzin at TU Bergakademie Freiberg, Germany
for developing sand detection sensor.
Dr. Sam Ramrattan at Western Michigan University, USA
for fundamental testing of aerated green sand.
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