Master of Simulation Techniques
Lecture No.5
„
„Fine
Fine Blanking
Blanking
“
“
Prof. Dr.-Ing. F. Klocke
Structure of the lecture ¾ Blanking
¾ Sheared surface and force
¾ Wear
¾ Blanking processes and blanking tools ¾ Errors on sheared workpieces
¾ Fine blanking
¾ Comparison to normal blanking
¾ Process details and degree of difficulty ¾ Tool setup and tool materials
¾ Examples of fine blanking parts
¾ Calculation of blanking processes
¾ analytical calculation method ¾ FEA of fine blanking processes
Separation processes
Influence of die clearance on the formation of cracks and sheared surfaces
Quality of sheared surface depending on specific die clearance
Qualitative diagram of cutting force in dependence on the cutting way
Structure of the lecture ¾ Blanking
¾ Sheared surface and force ¾ Wear
¾ Blanking processes and blanking tools ¾ Errors on sheared workpieces
¾ Fine blanking
¾ Comparison to normal blanking
¾ Process details and degree of difficulty ¾ Tool setup and tool materials
¾ Examples of fine blanking parts
¾ Calculation of blanking processes
¾ analytical calculation method ¾ FEA of fine blanking processes
Structure of the lecture ¾ Blanking
¾ Sheared surface and force ¾ Wear
¾ Blanking processes and blanking tools
¾ Errors on sheared workpieces
¾ Fine blanking
¾ Comparison to normal blanking
¾ Process details and degree of difficulty ¾ Tool setup and tool materials
¾ Examples of fine blanking parts
¾ Calculation of blanking processes
¾ analytical calculation method ¾ FEA of fine blanking processes
Differentiation of blanking and perforating
Multi-stage blanking tool
Structure of the lecture ¾ Blanking
¾ Sheared surface and force ¾ Wear
¾ Blanking processes and blanking tools ¾ Errors on sheared workpieces
¾ Fine blanking
¾ Comparison to normal blanking
¾ Process details and degree of difficulty ¾ Tool setup and tool materials
¾ Examples of fine blanking parts
¾ Calculation of blanking processes
¾ analytical calculation method ¾ FEA of fine blanking processes
Influence of the specific die clearance on the crack depth
Structure of the lecture ¾ Blanking
¾ Sheared surface and force ¾ Wear
¾ Blanking processes and blanking tools ¾ Errors on sheared workpieces
¾ Fine blanking
¾ Comparison to normal blanking
¾ Process details and degree of difficulty ¾ Tool setup and tool materials
¾ Examples of fine blanking parts
¾ Calculation of blanking processes
¾ analytical calculation method ¾ FEA of fine blanking processes
Comparison blanking - fine blanking
Animation fine blanking
Structure of the lecture ¾ Blanking
¾ Sheared surface and force ¾ Wear
¾ Blanking processes and blanking tools ¾ Errors on sheared workpieces
¾ Fine blanking
¾ Comparison to normal blanking
¾ Process details and degree of difficulty
¾ Tool setup and tool materials ¾ Examples of fine blanking parts
¾ Calculation of blanking processes
¾ analytical calculation method ¾ FEA of fine blanking processes
Stress states in the cutting zone in fine blanking
Fine blanked parts
Correlations of process variables in fine blanking
Structure of the lecture ¾ Blanking
¾ Sheared surface and force ¾ Wear
¾ Blanking processes and blanking tools ¾ Errors on sheared workpieces
¾ Fine blanking
¾ Comparison to normal blanking
¾ Process details and degree of difficulty ¾ Tool setup and tool materials
¾ Examples of fine blanking parts
¾ Calculation of blanking processes
¾ analytical calculation method ¾ FEA of fine blanking processes
Definition of degree of difficulty in fine blanking
Geometry of vee rings
Fine blanking of a disc by multi step blanking
Structure of the lecture ¾ Blanking
¾ Sheared surface and force ¾ Wear
¾ Blanking processes and blanking tools ¾ Errors on sheared workpieces
¾ Fine blanking
¾ Comparison to normal blanking
¾ Process details and degree of difficulty ¾ Tool setup and tool materials
¾ Examples of fine blanking parts
¾ Calculation of blanking processes
¾ analytical calculation method ¾ FEA of fine blanking processes
Fine blanked control disc (one step blanking)
Fine blanking of a clutchdisc
Wöhler-diagram for perforated sheet : Comparison fine blanking / machining
Structure of the lecture ¾ Blanking
¾ Sheared surface and force ¾ Wear
¾ Blanking processes and blanking tools ¾ Errors on sheared workpieces
¾ Fine blanking
¾ Comparison to normal blanking
¾ Process details and degree of difficulty ¾ Tool setup and tool materials
¾ Examples of fine blanking parts ¾ Calculation of blanking processes
¾ analytical calculation method
Calculation of blanking process
• Analytical calculation method
• FEA of (fine)blanking processes
Principals and drawbacks
Advantage over analytical calculation by means of examples
Calculation of blanking process - cutting force
S S S
s
l
k
F
max=
⋅
⋅
m SR
k
=
0
,
8
maximum cutting force s :sheet thickness lS :length of cutting line kS :cutting resistance
approximate calculation with tensile strength
Calculation of blanking process - cutting energy
( )
∫
=
g x S SF
x
dx
W
0 max S g Sc
x
F
W
=
⋅
⋅
cutting energy x :cutting distance FS:current cutting forcec :correction factor
including variables like material properties, effective cutting distance, size of die clearance and friction
Calculation of fine blanking process - vee ring force
m R R
R
l
h
R
F
= 4
⋅
⋅
⋅
approximation value for the vee ring forcelR :length of vee ring
hR :overall height of vee ring Rm:material tensile strength
Calculation of fine blanking process - counter punch force G q G
A
q
F
=
⋅
220
mm
N
q
G=
270
mm
N
q
G=
approximation for the counter punch force Aq :cutting piece surface
qG:specific counter punch force
Value of the specific counter punch force for small sized, thin workpieces.
Value of the specific counter punch force for big, thick workpieces.
Calculation of fine blanking process - cutting force
G St S
F
F
F
=
−
s
l
F
A
F
k
S S S S S=
=
⋅
max max m SR
k
C
1=
m g S g Sl
s
C
l
s
R
F
=
⋅
⋅
τ
=
1⋅
⋅
⋅
9
,
0
6
,
0
< C
1<
cutting force FSt:punch forceFG:counter punch force
Fsmax:maximum cutting force AS :shearing surface factor of shearing strength
kS :shearing resistance Rm:tensile strength
calculation according to VDI-standard 3345 lg :total length of cutting lines
s :material thickness τS :shear strength
C1:factor of shearing strength due to yield stress ratio
Rm:material tensile stress shearing resistance
Structure of the lecture ¾ Blanking
¾ Sheared surface and force ¾ Wear
¾ Blanking processes and blanking tools ¾ Errors on sheared workpieces
¾ Fine blanking
¾ Comparison to normal blanking
¾ Process details and degree of difficulty ¾ Tool setup and tool materials
¾ Examples of fine blanking parts ¾ Calculation of blanking processes
¾ analytical calculation method ¾ FEA of fine blanking processes
Simulation fine blanking
Simulation of fine blanking offers the opportunity to include:
This leads to the following results: • force over punch travel
• stress field • strain rate field • draw-ins
• prediction of fracture • flow stress data • friction properties
• thermomechanical coupling
More exact input data can be enclosed:
instead of
F
S=
C
1⋅
l
g⋅
s
⋅
R
m.
const
R
m=
Simulation fine blanking: Example
• material flow
detail
Simulation fine blanking: Example
Simulation fine blanking: Example
• strain-rate
Simulation fine blanking: Example
Simulation fine blanking: material flow as a function of friction
Simulation fine blanking: Example maximum principle stress in blanking punch and workpiece forces in the tool: •blanking die •blank-holder •blanking punch •counter-punch
Simulation fine blanking: Example
• stresses in the tool
Simulation blanking: Example
• workpiece fracture - deleting elements
Simulation fine blanking: Example
• 3D-simulation
-
draw-insSimulation fine blanking: Example
¾ What does the sheared surface look like in blanking ?
¾ Why is this surface not completely smooth ?
¾ Please explain the punch force over punch travel for blanking !
¾ Why are blanking tools made of hardened and tempered material ?
¾ Why are sheet metal parts of high quantity made preferably through blanking and not through CNC-wire Electro-erosion ?
¾ What is the maximum stroke frequency of a blanking machine ?
¾ Why is there an increased fraction of smooth surface in fine blanking in comparison to normal blanking ?
¾ What is the reason behind the difficulty classes in fine blanking ? Why can a protruding part be not arbitrarily thin ? Why can a radius not be arbitrarily small ?
¾ Can hardened and annealed materials be used as workpiece material in fine blanking ?
¾ What is the maximum plastic strain in fine blanking ?
