Study of Sheet Metal Stamping Processes
Transcript of Study of Sheet Metal Stamping Processes
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Two-stage stamping of cold drawn magnesium
alloy cup having small bottom corner.6.
Multi-stage stamping of tailor square blank forincrease in wall thickness at bottom corner ofsquare cup.
5.
Multi-stage stamping of high strength steel wheeldisk having large inner corner thickness.
4.
Two-stage stamping of tailor circular blank forincrease in wall thickness of wheel disk.
3.
Multi-stage stamping of wheel disk having largeinner corner thickness by means of conical punch.
2.
Introduction.1.
ContentsChapter
A study of sheet metal stamping processes
of lightweight partsFebruary 2008 Tan Chin Joo
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Chapter 1 Introduction
FlatSmallthickness: lowstrength
Localthickening
Large thickness:
high strength
Stamping
Tailor rolled blank
Long welding lines &high material loss
Tailor welded blank One-dimensional distribution
Control of thickness distribution of stamped products forreduction in weight
Proposed method for reduction in weight
Small thickness blank
Welding lines
Lightweight
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Forming of lightweight material forreduction in weight of parts
Density : 1/4 of mild steel
Specific strength : 2 times of mild steel
Advantages
Low formability at room temperature
Formed at elevated temperature Heating apparatus is expensive and
complicated
Disadvantages
Magnesium alloy
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Two-stage stamping of cold drawn magnesium
alloy cup having small bottom corner.
6.
Multi-stage stamping of tailor square blank forincrease in wall thickness at bottom corner ofsquare cup.
5.
Multi-stage stamping of high strength steel wheeldisk having large inner corner thickness.
4.
Two-stage stamping of tailor circular blank for
increase in wall thickness at inner corner at innercorner of wheel disk.
3.
Multi-stage stamping of wheel disk having largeinner corner thickness by means of conical punch.
2.Introduction.1.
ContentsChapter
A study of sheet metal stamping processes
of lightweight parts
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Chapter 2
Multi-stage stamping of wheel disk having largeinner corner thickness by means of conical punch
Steel Wheel
Welding
Roll forming
Bending, weldingMulti-stage stamping
Blanking
Disk forming Rim forming
Forming process of steel wheel
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Relationship between weight of wheel and fuel
consumption
Engine
Wheels
Drive shaft
Reduction in weight of wheel
Less fuel consumption
Wheels directly driven by engine
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Rim
Steel wheel
Local thickening at
Strength Fatigue life
Innercorner
Blank thickness
Disk
Target portion of wheel disk for local thickening
Hat portion
Drive shaft
Cracks in fatigue test
Rotating bending fatigue test
* K. Tanaka, K. Ishihara, H. Komatsu, Fatigue strength of car road wheels, SumitumoMetal, 39(4), p.325-336, 1987 (In Japanese).
T. Yogo, Method for producing automobile wheel disk, Japan Patent JP2004074248,2004 (in Japanese).
Forming of lightweight disk
*
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(a) 1st stage
(d) 4th stage
(b) 2nd stage
(e) 5th stage(c) 3rd stage
Decrease inthickness
Flat punchDie
Flat
punch Die
Drawn cup with flange
Outer punch
Outerdie
Innerpunch
Inner
punch
Outer
punch
Die
Middlepunch
Inner
punch
Innerdie
Outerdie
Outer
punchInnerdie Equal
Conventional multi-stage stampingof wheel disk
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Equivalent to inner corner
(c) 3rd stage(a) 1st stage (b) 2nd stage
Innerpunch
Inner die
Outerdie
Conicalpunch
Blankholder
Die
Conicalpunch
Die
Increase in wall thickness at inner corner
by means of conical punches
58.6 R5 R7
64.6
48.4R5
R7
55.4
50.1R2
R3.862.5
R3
~ 1/3.5 actual size of wheel disk
Increase inthickness
Largecompression
Outerpunch
Parameters for increase in thickness
2. Drawn volume ratio1. Punch angle,
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10 20 30
10
20
30
0Punch angle /
Punch
strokein2ndstage/mm
Drawn volume ratio, Vr0.470.44
0.410.38
Relationship between drawn volume ratio andpunch stroke
Total volume, VT
Drawn volume,V
Vr=V/VT
After 2nd stage
Drawn volume ratio
Conicalpunch
Die
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(a) 1st stage
Deformation behaviors for
=0 andVr=
0.44
(b) 2nd stage
(c) 3rd stage
Equivalent toinner corner
Equivalent toinner corner
-6.3%
3.7%
14.3%15.0%3.9%
8.5%
2.6%
Innercorner
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Deformation behaviors for =25 and Vr=0.44
(a) 1st stage (b) 2nd stage
(c) 3rd stage
Equivalent toinner corner
Equivalent toinner corner
-3.9%
9.2%
15%5.9%13.7%
-2%
2.9%
Innercorner
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Cross sections for =25 and Vr=0.44
(a) 1st stage (b) 2nd stage
(c) 3rd stage (d) 4th stage
(e) 5th stage
~1/3 of 13 inch wheel disk
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Thickness distributions of drawn cup
having Vr= 0.41 for
= 0, 20 and 30
(b) Experiment
Around inner corner
(a) Calculated
Distance from center / mmChange
inwallthic
kness/%
Around innercorner
6%
0
o
20o30o
0 20 40 60-30
-20
-10
0
10
Distance from center / mmChange
inwallthic
kness/% Around inner
corner6%
0o
20
o
30o
0 20 40 60-30
-20
-10
0
10
Change in wall thickness:(t - to)to
x 100%=
tHat portion
Hub hole Hub hole
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Thickness distributions of drawn cup
having Vr= 0.44 for = 0, 20 and 30
(a) Calculated (b) Experiment
6mm
Innercorner
Punch angle / o
After 2nd stage
After 3rd stage
Chang
einwallthickness
atinnercorner/%
25
9.4%Maximumincrease
0 10 20 30
-10
0
10
Changeinwallth
ickness
atinnercorner/%
10
0
10
100 20 30
After 2nd stage
After 3rd stage
Punch angle /o
Maximumincrease9.0%
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Average increase in wall thickness at inner cornerfor = 0, 20, 30 and different Vr
0 10 20 30-10
-5
0
5
10
15
Punch angle/A
verageincreaseinwall
thic
knessatin
nercorner
/%
Vr=0.47
0.44
0.41
0.38
Stretching
Compression
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10 20 30
5
10
15
20
25
0
50
100
150
200
250
0
Punch angle/M
aximumincreasein
wallthick
ness
atin
nercorner
/%
Ma
ximumformingload
in3rdstage/kN
Forming load
Increase in thickness
Vr=0.47
Vr=0.44
Optimum condition
Optimum forming condition for increase in wall
thickness at inner corner of wheel disk
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Chapter 2Multi-stage stamping of wheel disk having large innercorner thickness by means of conical punch
Average 10% increase in wall thickness aroundthe inner corner of the wheel disk was
successfully obtained by means of the conicalpunches.
The optimum forming conditions =25 and
Vr=0.44 were summarized. The blank thickness can be reduced without
decreasing the strength of the wheel for thereduction in weight
Conclusions
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Two-stage stamping of cold drawn magnesium
alloy cup having small bottom corner.
6.
Multi-stage stamping of tailor square blank forincrease in wall thickness at bottom corner ofsquare cup.
5.
Multi-stage stamping of high strength steel wheeldisk having large inner corner thickness.
4.
Two-stage stamping of tailor circular blank for
increase in wall thickness at inner corner of wheeldisk.
3.
Multi-stage stamping of wheel disk having largeinner corner thickness by means of conical punch.
2.Introduction.1.
ContentsChapter
A study of sheet metal stamping processes
of lightweight parts
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Chapter 3Stamping of tailor circular blank for increase in wall
thickness at inner corner of wheel disk
High material loss. Difficult to control laser welding process. High cost.
Disadvantages
Thin blank
Thick blank
Welding
Laser welding of tailor circular blank
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(a) 1st stage
(b) 2nd stage
(c) 3rd stage
Outer punch
Outer
dieInner die
Punch Die
Innerpunch
Drawn cup with flange
Blankholder
Punch
Die
(b) 2nd stage
(a) 1st stage
2-stage stamping of
tailor circular blank3-stage forming of
drawn cup with flange
Increase in thickness
Large inner cornerthickness
Wheel disk
Punch Die
Punch Blankholder
Die
Stamping of tailor circular blank for increase in wall
thickness at inner corner of wheel disk
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Conditions for local thickening process
i) Stroke, sii) Clearance between punch
and die, c
Parameters :
18
54
R8 Blankc
Blankholder
PunchR4 R4
Die
Die
Restrictedby friction
Increase inthickness
c
Material wasdrawn intodie cavity
PunchBlankholder68
s
(a) 1st stage
(b) 2nd stage
Lowcompression
Highcompression
Equivalent portion
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Deforming behavior for local thickening process
(s = 6.5mm, c=2mm)
(a) 1st stage
-3.1%
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Deforming behavior for local thickening process
(s = 6.5mm, c=2mm)
(b) 2nd stage
12%
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Change
inwallthickness/%
Distance from bottom center / mm
3.54.55.56.5
7.5
s / mm
Equivalentportion
0 20 40 60-30
-20
-10
0
10
20
30
Calculated effect of stroke in 1st stage
of local thickening process
Equivalent portion
(c=2mm)
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Distance from bottom center / mmChang
einwallthickness/%
s / mm
Equivalentportion
12
Flat
3.54.55.56.57.5
0 20 40 60-30-20
-10
0
10
20
30
Effect of stroke in 2nd stage
of local thickening process
(a) Calculated (b) Experimental
Equivalent portion
Distance from bottom center / mmChang
einwallthickness%
3.54.55.56.57.5
s / mm
12
Equivalentportion
Flat
0 20 40 60-30-20
-10
0
10
20
30
(c=2mm)
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Effect of clearance in local thickening process
6.5Punch stroke in 1st stage s / mmMa
x.
increase
inwallth
ickness
intargetportion/% c / mm2
34
3 4 5 6 7 80
2
4
6
8
10
12
14
Tailor circular blank was formed with the conditionss = 6.5mm, c=2mm
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Stroke in 1st stage s / mm
Max
imumform
ingload
in
2ndstage
/kN
Maxim
umincrea
seinwall
thicknes
sintarget
portion/%
Load
Thickness
6.5
12
4 5 6 70
50
100
150
200
-30
-20
-10
010
20
30
Forming load in 2nd stage andincrease in wall thickness at target portion
for different punch strokes in 1st stage(c=2mm)
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15
mm
58.6
13.5
mm
64.6
120
(a) 1st stage (b) 2nd stage (c) 3rd stage
36.82R3.8
R2.0 R19.4
50.1
R8.0
Punch DieInnerPunch
Outer
punch
Outerdie
Inner die
Blank-holder
48.4
55.4
Conditions for 3-stage forming of drawn cup with
flange from tailor circular blank
1.6mm
Tailor circular blank
1
3.5
of actual disk
Punch Die
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Deforming behavior for 3-stage forming of drawn
cup with flange from tailor circular blank
1st stage
7.8%
(s=6.5mm, c=2mm)
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5.9%
Deforming behavior for 3-stage forming of drawn
cup with flange from tailor circular blank
2nd stage
(s=6.5mm, c=2mm)
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14%
Deforming behavior for 3-stage forming of drawn
cup with flange from tailor circular blank
3rd stage
(s=6.5mm, c=2mm)
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11
3
Around innercorner
Distance from bottom center / mmChangeinwallthickness
%
tailorflat
0 20 40 60-30
-20
-10
0
10
2030
Wall thickness distribution of drawn cup with flange
formed from tailor circular blank
Around inner corner
Hub hole
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Chapter 3Two-stage stamping of tailor circular blank forincrease in wall thickness of wheel disk.
Extra 8% increase in wall thickness at the innercorner of wheel disk was successfully obtainedby the tailor circular blank.
Extra 2 stages of the local thickening processwere added to the conventional multi-stagestamping of wheel disk for the increase.
The cross sectional shape of the drawn cupformed from the locally thick blank is almost thesame with the one formed from the flat blank.
Conclusions
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Two-stage stamping of cold drawn magnesiumalloy cup having small bottom corner.
6.
Multi-stage stamping of tailor square blank forincrease in wall thickness at bottom corner ofsquare cup.
5.
Multi-stage stamping of high strength steel wheeldisk having large inner corner thickness.
4.
Two-stage stamping of tailor circular blank forincrease in wall thickness at inner corner of wheeldisk.
3.
Multi-stage stamping of wheel disk having largeinner corner thickness by means of conical punch.
2.
Introduction.1.
ContentsChapter
A study of sheet metal stamping processes
of lightweight parts
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(c) 3rd stage(a) 1st stage (b) 2nd stage
Innerpunch
Outerpunch
Inner die
Outerdie
Conicalpunch
Die
Conicalpunch
Die
58.6
R5 R7
64.6
48.4R5
R
7
55.4
50.1R
2R3.862.5
R3
~ 1/3.5 actual size of wheel disk
2525
Increase inthickness
Equivalent to inner corner
Largecompression
25.
2
25.
2
( =25 and Vr=0.44)
Chapter 4
Multi-stage stamping of high strength steelwheel disk having large inner corner thickness
Drawn cup with flange
Forming conditions
Blankholder
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1.41.6Blank thickness / mm
=943.7 0.18 =629 0.15Flow stress / MPa590 Mpa408 MPaTensile strength / MPa
High strength
steel
Mild steelMaterial properties
Material properties
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Thickness distributions of mild steel and
high strength steel drawn cups
12.57.2
Mild
High strength
Aroundinner corner
Distance from center / mmChangeinwallthickness/%
1.61.4
Thickness / mm
0 20 40 60-40
-20
0
20
Inner corner
Less increase in thicknessat inner corner!!!
Hub hole
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Thickness distributions of drawn cups fordifferent blank thicknesses
Blank thickness / mmMax.
increasein
wallthickn
ess
atin
nercorner/%
Blank material=mild steel1.2 1.4 1.6 1.8 20
5
10
15
20
Inner corner
Decrease in blank thickness lead to small increase in thickness
at inner corner
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Conditions for 2-stage stamping of tailor
circular blank for high strength steel wheel disk
18
54
R8 Blank3
Blankholder
Punch
R4 R4
Die
Die
Restrictedby friction
Increase inthickness
Material wasdrawn intodie cavity
PunchBlankholder68
s
(a) 1st stage
(b) 2nd stage
LowcompressionHighcompression
Equivalent portion
3
Punch stroke s is a parameter
1.4mm
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-2%
Deformation behaviors of 2-stage stamping of
tailor blank for s=8.5
(a) 1st stage
Plasticequivalent strain
0.800
0.7330.6670.6000.5330.4670.4000.3330.2670.200
0.1330.0670.000
D f ti b h i f 2 t t i f
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13%
Deformation behaviors of 2-stage stamping oftailor blank for s=8.5
1.570
1.0000.9090.8180.7270.6360.5450.4550.3640.273
0.1820.9090.000
Plasticequivalent strain
(b) 2nd stage
Influence of punch stroke in 1st stage on
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Punch stroke in 1st stage s / mm8.5
8.2
Averageincreasesinthick
ness
atequivalentportion
/%
Maximum
7 8 90
2
4
6
8
1012
14
Influence of punch stroke in 1st stage onamount of local thickening
Equivalent portion
Forming of tailor blank using s=8.5mm
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10%
Deformation behaviors of 3-stage stamping of
tailor blank for s=8.5Plasticequivalent strain
1.900
1.7401.5801.4201.270
1.1100.9500.7920.6330.4750.3170.1580.000(a) 1st stage
Deformation behaviors of 2 stages stamping of
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Deformation behaviors of 2-stages stamping oftailor blank for s=8.5
1.0901.0000.9090.8180.727
0.6360.5450.4550.364
0.2730.1820.0910.000
5%
Plasticequivalent strain
(b) 2nd stage
Deformation behaviors of 2 stages stamping of
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Deformation behaviors of 2-stages stamping oftailor blank for s=8.5
2.260
2.0001.8201.6401.4501.2701.0900.9090.7270.545
0.3640.1820.000
18%
Plasticequivalent strain
(c) 3rd stage
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7.214.5
Distance from center / mmChangeinwallth
ickness/%
Aroundinner corner
Tailor
Flat
0 20 40 60-40
-20
0
20
Thickness distributions of drawn cups
formed from tailor and flat blanksInner corner
Amount of thickeningbecomes double !!!
Hub hole
C i f i i h l di k
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Tailor blank
(a) Disk formed from
flat blank
94.1 21.9mm
21.0mm
94.1
(b) Disk formed from
tailor blank
Wrinkle
Cross sections of miniature wheel disk
formed from tailor and flat blanks
8mm
8m
m
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Chapter 4Multi-stage stamping of high strength steel wheel diskhaving large inner corner thickness
The increase in wall thickness at the inner cornerof the high strength steel wheel disk becomessmall due to the decrease in blank thickness.
The high strength steel wheel disk formed fromthe tailor circular blank has 2 times of degree ofincrease in thickness at the inner corner ifcompared to the one formed from the flat blank.
The cross section of high strength steel wheeldisk formed from tailor blank is almost the same
with the one formed from flat blank.
Conclusions
A study of sheet metal stamping processes
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Two-stage stamping of cold drawn magnesiumalloy cup having small bottom corner.
6.
Multi-stage stamping of tailor square blank for
increase in wall thickness at bottom corner ofsquare cup.
5.
Multi-stage stamping of high strength steel wheeldisk having large inner corner thickness.
4.
Two-stage stamping of tailor circular blank forincrease in wall thickness at inner corner of wheeldisk.
3.
Multi-stage stamping of wheel disk having largeinner corner thickness by means of conical punch.
2.
Introduction.1.
ContentsChapter
A study of sheet metal stamping processes
of lightweight parts
Chapter 5
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Local thickening method
Chapter 5Multi-stage stamping of tailor square blank forincrease in wall thickness at bottom corner ofsquare cup
Rotate 90 for2nd thickeningoperation
(a) After 1st stage (b) After 2nd stage1st thickened portion
Constraint
Compression
1st thickening operation
C diti f thi k i ti
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(c) Dimension of ditch in detail
Inner die
Punch
46.0
34.032.0
48.0
0.1
5
0.1
5
Outer die
PunchHolder
Punch
Die
R5.0R
6.6
34.0
46.0
45.333.3
R5.0 R6.6
90.0
80.0
(b) 2nd stage
1stthickened
portion 49.6
76.4
0.2Ditch
Stopper
1.6
(a) 1st stage
Inner die
4.6
Squareblank
Conditions for thickening operation
=40, 45, 50, 55, 60
Parameter
symmetry along vertical axis
Deformation behavior for multi-stage stamping
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Deformation behavior for multi stage stamping
of tailor square blank for= 55
(a) 1st stage
1
4model
Deformation behavior for multi-stage stamping
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(b) 2nd stage
20%increase inthickness
Deformation behavior for multi stage stamping
of tailor square blank for= 5514
model
Deformation behavior for multi-stage stamping
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(c) 3rd stage
Deformation behavior for multi stage stamping
of tailor square blank for= 55
Ditch
1
4model
Deformation behavior for multi-stage stamping
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Ditch
Ditch
Ditch
1st thickened portion33% increasein thickness
Deformation behavior for multi stage stamping
of tailor square blank for= 55
(d) 4th stage
1
4model
D f d t il bl k bt i d f
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X
Y
Z
Max. 33% increasein thickness
~1mm
~1mm
Bulging
75m
m
75mm
Deformed tailor square blank obtained from
simulation for= 551
4model
Cross sections of tailor square blank after 1st
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(a)= 50
(b)= 55
(c)= 60
Buckling71.8
74.0
76.8
Cross sections of tailor square blank after 1st
thickening operation for different
Thickness distributions of tailor square blank
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Thickness distributions of tailor square blank
after 1st thickening operation for different
D istance from center / m mChangeinwallthickness/%
18
/
Target
portion
0 10 20 30 40
0
10
20
30
455055
Thickness distribution along 1st thickened
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Thickness distribution along 1st thickened
portion of tailor square blank after 2ndthickening operation
Distance along X=18 from Y=0
33
0 10 20 30 40
10
20
30
40 Cross between 1stand 2nd thickened
portions
Less increase inthickness due to
bulging
Portion equivalent
to inner cornerChangeinwall
thickness/%
Deformation behavior for deep drawing of
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10% Increase inthickness
p g
square cup from tailor square blank
X
Y
Z
R6
R636mm
Punch
Die
R6
75mm
36mm
R6
54mm54m
m
75mm
R
6
R6
(a) Conditions (b) Deformation behavior
C i f f d f
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(a) Formed from tailor blank (b) Formed from flat blank
+10% -17%
Die
of cup
Punch
Blank holder
Bottomcorner
Cross sections of square cup formed fromtailor blank and flat blank
Highstrength Lowstrength
Thickness distribution of square cup formed
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Thickness distribution of square cup formed
from tailor square blank
Distance of bottom edge along X=18 / mm
Changeinwallthickness/%
Cup formed fromflat blank
Cup formed fromtailor blank
Tailor blank
-17Bottom corner
10
0 10 20 30 40
-20
0
20
40
Conclusions
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Chapter 5Multi-stage stamping of tailor square blank forincrease in wall thickness at bottom corner of squarecup
The tailor square blank was successfully formedby stamping process.
The tailor square blank having maximum 33%increase in wall thickness at the portionequivalent to the bottom corners of the squarecup was formed.
The square cup formed from the tailor blankhave 10 % increase in wall thickness at bottomcorners if compare to the one formed from flat
blank having 17% decrease in wall thickness.
Conclusions
A study of sheet metal stamping processes
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Two-stage stamping of cold drawn magnesiumalloy cup having small bottom corner.
6.
Multi-stage stamping of tailor square blank for
increase in wall thickness at bottom corner ofsquare cup.
5.
Multi-stage stamping of high strength steel wheeldisk having large inner corner thickness.
4.
Two-stage stamping of tailor circular blank forincrease in wall thickness at inner corner of wheel
disk.
3.
Multi-stage stamping of wheel disk having largeinner corner thickness by means of conical punch.
2.
Introduction.1.
ContentsChapterof lightweight parts
Chapter 6
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Chapter 6
Two-stage stamping of cold drawn magnesiumalloy cup having small bottom corner
PunchBlankholder
Die
Coolant
Heater
Casing of laptop formedby hot stamping process
Heating apparatus is expensive and complicated
Disadvantage
Conditions for two-stage stamping of cold drawnmagnesium alloy cup having small bottom corner
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magnesium alloy cup having small bottom corner
(a) 1st stage
Die
Blankholder
Drawn cup
Outer punch
Container
Inner punch
Coil spring
bRp=5mm
Crack
aRp=1mm
Rp=5mm
Punch
Drawn ratio =1.72 (b) 2nd stage
18.620.0 R4
19.818.810.0
s
Smallbottomcorner
Deformation behavior for round magnesium
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cup having small bottom corner
(a) 1st stage (b) 2nd stage
Cross sections of round magnesium cup having
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Cross sections of round magnesium cup having
small bottom corner
R1.1
7.
2
18.918.9R5.0
9.
4
s=2.6m m (a) 1st stage (b) 2nd stage
Height and bottom corner radius of round cup
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Height and bottom corner radius of round cup
for different punch strokes in 2nd stage
0.5 1 1.5 2 2.5 3
2
4
6
8
10
0
1
2
3
4
5
6
0Punch stroke in 2nd stage / mm
Heightofcup/mm
Bottomcorner
radius/m
m
Bottomcorner radius
Height of cup
Crack at bottom corner
s=2.8mm
Limit forcrack
Experimental
Calculated
2.8
Introducing conical punch and ironing die in 1st stageof cold stamping of round magnesium alloy cup
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a= 140
(b)= 150
R=5
R420.0
18.6
Blank Holder
Ironingdie
Conicalpunch
Blank
Crack
19.69
Drawingdie
of cold stamping of round magnesium alloy cup
Maximum
to= 0.5
b
Ironing ratio, a= (to-b)/ to
Cross sections of round magnesium cup
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R1.1
7.
2
18.9
7.3
0.6
18.9
(a) By flat punch
for s=2.6mm
(b) By conical punch
for s=2.9mm
(c) By conical punch
for s=3.4mm anda=20%
Straight
7.8
0.5
18.7
Cross sections of round magnesium cup
obtained from experiment
Conditions for two-stage stamping of magnesium
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square cup having small bottom corner radius
R3.4
R4
R4R4
18
.8
18.8
20.0
20
.0
(a) 1st stage
(b) 2nd stage
Squarecup
Outer punch
1018.8
19.8
Container
Innerpunch
27
R8.1
Square blankSmall
bottom
corner
Magnesium square cups obtained from experiment
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R3.7
5.
2 R0.6
3.
8
(a) 1st stage (b) 2nd stage
Conclusions
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Chapter 6Two-stage stamping of cold drawn magnesium alloycup having small bottom corner
The round and the square magnesium alloy cupshaving small bottom corners were successfullyformed at room temperature.
An extra stage is added for reducing the bottomcorner radius.
The employment of the conical punch and theironing die improved the dimensions of the cup
List of publications
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Reviewed journals:1. Chin Joo Tan, Yohei Abe, Ken-ichiro Mori, Takayuki Nonaka and Osamu Ebihara,Increase of wall thickness around corner of multi-stage drawn cup with flange usingconical punches, Key Engineering Materials, vol. 340-341, p. 761-766, 2007.
2., Chin Joo Tan,,,,,,., Journal of Japan Society for
Technology of Plasticity, vol. 48, no. 561, p. 55-59, 2007.3. C. J. Tan, K. Mori and Y.Abe, Multi-stage stamping of high strength steel wheel disk,
Journal of advanced manufacturing technology (Spec. ed.), vol. 1, no. 1, p.31-47,2007. (ISSN:1985-3157).
4. C. J. Tan, K. Mori and Y.Abe, Forming of tailor blanks having local thickening forcontrol of wall thickness of stamped products, Journal of Material ProcessingTechnology, in press. 2007.
Reviewed Conference papers:5. C. J. Tan, K. Mori and Y.Abe, Increase in wall thickness at inner corner of multi-stage
stamping of wheel disk by locally thick blank, Proc. 2nd International Conference on
New Forming Technology (ed. F. Vollertsen et al.), p.371-380, 2007.6. C. J. Tan, K. Mori and Y.Abe, Forming of high strength steel wheel disk having largeinner corner thickness. Proc. International Conference on Engineering & ICT, vol. 1,p.41-48, 2007. (Best paper award).
Drawn cup for =25 and Vr=0.44
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(b) 1st stage(a) Blank
(c) 2nd stage (d) 3rd stage
12mm
Effect of angle of bulging ring in local
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Max.in
creasein
wallthic
kness
in
targetpo
rtion/%
Angle of bulging ring / o43
c / mm
234
0 10 20 30 40 50 60
2
46
8
10
12
14
thickening process
Reason for decrease in thickness for s = 7.5mm
(c=2mm)
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(i) s= 7.5mm (ii) s = 6.5mm
53 43
DieOuterpunch
DieOuterpunchInner punch
Equivalentportion
Increase inthickness
Inner punch
Highcompression
LowcompressionHighcompression
Lowcompression
Increase inthickness
( )
Photographs of deformed discs
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(a) 1st stage (b) 2nd stage
10mm
2-stages local thickening process (s=6.5mm, c=2mm)
10mm
Drawn cup with flange
(ii) Formed fromflat blank
(i) Formed fromlocally thick blank
Thickness distributions of drawn cups fordifferent materials
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Aroundinner corner
Mild
Highstrength
Distance from center / mmCha
ngeinwal
lthickness
/%
Blank thickness = 1.4mm
0 20 40 60-40
-20
0
20
Inner corner
High strength steel has no influence on the increase in thickness
Forming of high strength steel drawn cupfrom tailor circular blank
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Outer punch
Outerdie
Inner die
Inner
punch
Drawn cup with flange
Blankholder
Punch
Die
(b) 2nd stage
(a) 1st stage
2-stage stamping oftailor circular blank 3-stage forming of
drawn cup with flange
Increase in thickness
Large inner cornerthickness
High strength steel
wheel disk
Punch Blankholder
Die
(a) 1st stage
Conicalpunch Die
Holder
Die
(b) 2nd stage
(c) 3rd stage
Equivalent toinner corner
Forming load in 2nd stage for s = 8.5mm
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Die
PunchBlankholder
2 4 6 8 10
50
100
150
200
0
Punch stroke s / mm
Form
ingload/k
N2nd
1st
Miniature wheel disks formed fromtailor and flat blanks
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(a) Formed from flat blank
10mm
10mm
(b) Formed from tailor blank
Deformation behaviors of thickening operation
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for=55
(b) 2nd stage(a) 1st stage
18%
Targetportion
Chapter 5Multi-stage stamping of tailor square blank for
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increase in wall thickness at bottom corner ofsquare cup
80
40
6 6
40
(a) 1st thickening operation (b) 2nd thickening operation
90rotation
6 6
1st thickenedportion
2nd thickenedportion
Equivalent to bottom corners of square cup
Double thickening
80
4
0
Equivalent tobottom edgesof square cup
Distribution of thickness and hardness of round
i i
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cup in two-stage stamping process
Thickness/mm
2 4 6 8 10 12 14 16
0.2
0.4
0.6
0.8
1
0
20
40
60
80
100
0Distance from bottom center / mm
Hardness/Hv
Hardness
Thickness
1st stage2nd stage
Initial thickness
Aroundbottom corner
Deformation behaviors of cup for= 150
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(a) 1st stage
0.5490.5060.4630.4200.377
0.3340.2910.2480.205
0.1620.1190.0760.033
Plasticequivalent strain
Deformation behaviors of round magnesium cupfor= 150
Pl ti
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(b) 2nd stage
0.9500.879
0.8080.7370.6660.596
0.5250.4540.3830.3120.241
0.1710.010
Plasticequivalent strain
Relationship between height of cup and bottomcorner radius for different punch strokes in 2nd
t f 20% & 150
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stage for a=20% &= 150
1 2 3 4
2
4
6
8
0
0.5
1
1.5
2
0Punch stroke in 2nd stage s / mm
Heightof
cup
/mm
Bottomcornerradius/mmHeight
RadiusLimit for
crack
Crack
Distribution of thickness strain and hardness of cup
ft 1 t d 2 d t f 20% &
150
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after 1st and 2nd stage for a=20% & = 150
0 2 4 6 8 10 12 14 16 18-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0
20
40
60
80
100
Distance from bottom center / mm
Thicknessstrain
Hardness/HV
Hardness
Strain
1st2nd
Bottom cornerafter 2nd stage
Distribution of thickness strain and of
h d l ti f
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hardness along cross section of square cup
0 2 4 6 8 10 12 14-0.3
-0.2
-0.1
0
0.10.2
0.3
0
20
40
60
80
100
Distance from bottom center / mm
Thickn
essstrain
Hardness/Hv
Thickness strain
Hardness
1st2nd
Aroundbottom corner
Relationship between forming load in 3rd
stage and conical punch angle
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10 20 30
50
100
150
200
250
0Punch angle/
Formingloadin3rdstage/kN
Vr
=0.47
0.44
0.41
0.38
stage and conical punch angle