Transcript No Slide Title

CPF
Servo Press Technology
Applications for Today and Tomorrow
Eren Billur and Taylan Altan
Center for Precision Forming
The Ohio State University
www.cpforming.org & www.ercnsm.org
August 23, 2012
Stamping Group
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Servo-Drive Presses- Outline
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CPF
Introduction
Servo-Drive Characteristics
Servo-Drive Press Mechanisms
Applications
Die Cushions
Summary/ Future Outlook
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Servo-Drive Characteristics
(1)
(1) Variable
Variable
stroke
stroke
length
length
(2)
(2) Best
Best speed
speed
for
materials
for materials
Minimum stroke length
Slide Position
Fixed Motion
Cycle time of mechanical press
Free motion press
Cycle time of
Free motion press
(6)
(6) Synchronize
Synchronize with
with
feeder
feeder
Forming length
Crank or Link press
CPF
Time
Standstill at BDC
(3)
(3) Improve
Improve
accuracy
accuracy by
by
dwelling
at
dwelling at BDC
BDC
(5)
(5) Prevention
Prevention of
of
noise
noise and
and shock
shock
at
at contact
contact or
or
breakaway
breakaway of
of
tools
tools
(4)
(4) Other
Other Process
Process
at
BDC
at BDC
(Multi
(Multi Process)
Process)
The flexibility of slide motion in servo drive (or free motion) presses. [Miyoshi, 2004]
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Servo-Drive Characteristics
CPF
• Precise ram position and velocity control, anywhere in
stroke-easier set up
• Adjustable stroke length (TDC and BDC)
• Ram position/ velocity can be synchronized with automatic
part transfer
• In deep drawing, cycle times can be shorter than in
mechanical presses
• Considerable savings in energy
• Dwell at BDC/ restriking/ vibrating and variable blank
holder force (BHF)
• Max. motor torque available during the entire stroke
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Servo-Drive Mechanisms
CPF
• Low Torque/ High RPM Motors Use Ball
Screws or/and Linkage Mechanisms
• High Torque/ Low RPM Motors Use
Existing Crank and/or Link Press Drives
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High RPM/ Low Torque
Motor Drive 1/2
CPF
Servo Motor
Timing
belt
Ball Screw
Slide
Linear sensor
Bolster
Schematic of servo press with high speed-low torque servo-motors with belt and
ball screw drive. [Miyoshi, 2004]
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High RPM/ Low Torque
Motor Drive 2/2
Servo Motor
CPF
Servo Motor
Slide
Linear
sensors
Eccentric
load
Linear
sensors
Right / Left independent control
Schematic of servo press with high speed-low torque servo-motors with linkage
drive. [Miyoshi, 2004]
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Low RPM/ High Torque
Motor Drive 1/2
Power Source
Balancer tank
CPF
Main gear
Capacitor
Servomotor
Drive Shaft
a) C-Frame Servo Press (Aida)
b) Stroke-Time program for warm
forming of Al and Mg sheet
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Low RPM/ High Torque
Motor Drive 2/2
CPF
Servo-Press Drive Using Conventional Crank Mechanism
Courtesy- Aida
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Hybrid Servo Press
Block diagram of a hybrid servo press (ABB)
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CPF
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Hybrid Servo Press
CPF
Simplified 3D-view of a hybrid servo press, seen from above
(ABB)
Stamping Group
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Modern Stamping Lines Using
Large Servo-Drive Presses
CPF
• BMW- Leipzig & Regensburg (Germany) – SCHULER
2009 - 2500 ton servo-drive drawing press - 17 SPM
• BMW – Leipzig, Regensburg and Shenyang (China) –
SCHULER – 2012 – 7 tandem lines on order.
• HONDA - Suzuka (Japan) – AIDA 2009 – 2500 ton
tandem line – 18 SPM
• Kamtek/COSMA – AIDA 2011 - 3,000 ton, 30
strokes/min
• Honda-America – Ohio and Alabama - AIDA 2012 2,500 ton tandem lines
• Hyundai – Korea – ROTEM 2012 – 1000 ton Tandem line
• Others ?
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Schematic of Servo-press tandem line (Aida/Honda)
CPF
2500 ton/ 18 SPM (2009)
Improved
Formability
・System with optimized press
forming requirements for each
product
Improved
Productivity
・Press-to-Press Loading Motion:
System is optimized for each
product.
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Energy-Saving
・Die cushions have an energy
regeneration system
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Servo-press tandem line (Schuler/BMW)
2500 ton/ 17 SPM (2009)

CPF
One drawing press + 5 presses for follow-up operations
Technical Data:
Total press force:
Drawing press force:
Total length of press line:
Length o press:
Strokes per minute:
Source:BMWarchive.de
Source:Schulergroup.com
Stamping Group
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10,300 tons
2,500 tons
98 meters
34 meters
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Servo Tandem Line at Suzuka (Japan) Plant
(Honda)
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CPF
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Applications- Deep Drawing 1/3
(Courtesy- Schuler)
Comparison between the slide motions of an 1100 mechanical and servo drive
press for identical slide velocity during forming [Bloom, 2008].
Stamping Group
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CPF
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Applications- Deep Drawing 2/3
(Courtesy- Schuler)
Decrease in cycle time by reducing the stroke length and operating the servo
press in “pendular” mode (progressive die stamping, 200% increase in output)
[Bloom, 2008]
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CPF
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Applications- Deep Drawing 3/3
(Courtesy- Schuler)
Decrease in cycle time as well as in impact speed using a servo press (150%
increase in output) [Bloom, 2008]
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CPF
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Side Panel Outer Deep Drawing Case
Example (Honda)
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CPF
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Applications- Blanking/ Ironing
CPF
Precision Formed Part a) partially
blanked, b) finished blanked
[Miyoshi, 2004 / Komatsu]
Slide motion used for partial and
finish blanking [Miyoshi, 2004 /
Komatsu]
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Applications- Reduction of Springback CPF
(Courtesy- Komatsu/ Hamamoto)
Item
: Eye glass frame
Material : Titanium based Shape-memory Alloy
Three processes had been
required to control the
springback.
By multiple step motion,
Three processes turned
into single process.
Multiple step motion
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Applications- Blanking/ Ironing
Courtesy – Aida)
CPF
IT IS POSSIBLE TO DIGITALLY SET
THE OPTIMAL WORKING SPEED,
THEREBY INCREASING DIE LIFE.
Al
STEPPED HOLE PIERCING
(80% BURNISHED SHEAR
FACE)
SUS304
PIERCING A HOLE WITH A
SMALLER DIAMETER THAN
THE MATERIAL THICKNESS
(INCLINED HOLE PIERCING)
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Applications- Blanking/ Ironing
(Courtesy – Aida)
CPF
SINCE THE PRESS CAN BE RUN AT LOW SPEEDS, IT IS NOT
NECESSARY TO SWITCH TO A LARGER CLASS PRESS TO
FORM HARD-TO-DRAW MATERIAL.
DRAW WRINKLES CAN BE
AVOIDED BY SLOWING DOWN
THE DRAWING SPEED.
(SINCE WORKING ENERGY IS ALWAYS
AVAILABLE, THE PRESS DOES NOT STOP
EVEN AT INCHING SPEEDS.)
WRINKLES CAN OCCUR WHEN
THERE IS INSUFFICIENT PRESS
RIGIDITY AND THE DRAWING
SPEEDS ARE NOT OPTIMIZED.
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Applications- Auxiliary Operations
(Courtesy – Aida)
CPF
IT IS POSSIBLE TO SET THE
OPTIMAL FORMING MOTION AND
TIMING FOR SECONDARY
PROCESSES.
(STAKING AND ASSEMBLY)
STAKING A PIN (∅3.6) IN A CHASSIS
DURING A PROGRESSIVE FORMING
OPERATION
ASSEMBLY OPERATION OF A
SQUARE NUT (M5) IN A BRACKET
DURING A PROGRESSIVE FORMING
OPERATION
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Applications- Warm Forming of
Al, Ti, Mg, and SS
CPF
Tool and process design guidelines to improve formability
Power Source
Balancer tank
Main gear
Capacitor
Servomotor
Drive Shaft
Aida Servo Press (used in warm forming of Al, Mg and Ti sheet)
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Applications- Warm Forming of Al
CPF
Preliminary results (Velocity range : 2.5-50mm/sec)
AL 5754- O
AL 5052-H32
T (oC)
LDR
T (oC)
LDR
RT
2.1
RT
2.1
250
2.5
275
2.5
300
2.9
275
2.9
Note : RT: Room temperature, LDR : Limit draw ratio
Cup Diameter : 40mm
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Applications- Warm Forming of
Mg and Ti
CPF
Preliminary results (Velocity range : 5-50mm/sec)
Mg AZ31-O
Ti (Grade 1)
T (oC)
LDR
RT
-
275
2.6
T (oC)
LDR
275
3.2
310
2.5
Note : RT: Room temperature, LDR : Limit draw ratio
Cup Diameter: 40mm
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Applications- Warm Forming of
Mg Lap Top Case
Press slide motion used in warm
forming processes (TDC - Top Dead
Center, BDC – Bottom Dead Center)
CPF
Warm formed lap top case from Mg alloy
(Courtesy – AIDA)
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CPF
Die Cushion Force (kN)
Servo-Hydraulic Cushion
(Courtesy-Aida)
Elimination of Pressure Surge in the Die Cushion
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Capabilities of the Self-Driven Hydraulic
Servo Cushion
CPF
• pre-acceleration to reduce the impact speed
between the die and blank holder
• variable pressure / force capability to control
blank holder force/pressure during stroke
• prevention of momentary return of the cushion
after BDC to avoid pressure on the top of the part
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Servo-Hydraulic Cushion
(Courtesy-Aida)
CPF
Power Regeneration: Approx. 70%
Power
Direction
Motor Torque
Direction
Pump
Rotation
Direction
Linear
Scale
S/M
S
M
Pressure Sensor
Closed Hydraulic Circuit
During Down Stroke, Cushion Pressure Generates Power
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Advantages of Servo- Press Technology CPF
- Applications in Forming AHSS 1. Major Challenges in Forming AHSS (DP, TRIP,
TWIP) include:
• lower formability (ductility) and higher probability of fracture
• variations in mechanical properties form batch to batch
• higher forming forces and high sheet/die interface pressures &
temperatures
• Excessive tool wear, rapid increase in down-force and large
reverse tonnage
• large springback due to large tensile strength
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Advantages of Servo- Press Technology
- Applications in Forming AHSS -
CPF
2. Precise Ram Position (including dwell) and
velocity control
•
•
•
•
allows for easier die set-up
prevents noise and shock when the ram is contacting the
workpiece (hydraulic cushion with pre-acceleration)
improves formability and reduces fracture by reducing ram
velocity during deformation (drawing, stretching and bending),
improves die/sheet lubrication by reducing temperature increase
at sheet/die interface
reduces shock loading and reverse tonnage in blanking,
improves tool life
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Advantages of Servo- Press Technology
- Applications in Forming AHSS -
CPF
3. Dwell at BDC and Pendulum Motion allows:
• dwell at BDC and restriking quickly through pendulum motion
before the formed material fully strain hardens, reduces springback
(die design is still very important)
4. Adjustable Stroke Length (TDC to BDC):
•
provides flexibility so that in the same press, drawing, blanking
and coining can be conducted with maximum productivity (high
strokes/min)
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Advantages of Servo- Press Technology
- Applications in Forming AHSS -
CPF
5. Ram Position/Velocity can be:
•
synchronized with automatic (or robotic) part
transfer to increase strokes/min
•
adjusted to maximize strokes/min while maintaining
lower ram velocity during forming stage
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Servo-Drive Press Technology
Summary / Outlook
CPF
• Gap presses up to 150 ton are in production (15+ years)
• Straight Side stamping presses up to 3000 ton are already
built
• Direct drive (high torque) motors and energy recovering
cushions are used
• High speed automotive stamping transfer presses (18
strokes/min)/ Schuler-BMW/ Aida-Honda and Cosma /
Komatsu-Toyota & others
• Novel tool design techniques for servo drive technology are
being developed
• Servo-drive presses will greatly contribute to improving the
technology for forming AHSS and Al alloys
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Questions/Comments
CPF
Taylan Altan, Professor and Director
Center for Precision Forming (CPF)
www.cpforming.org / www.ercnsm.org
The Ohio State University, Columbus, OH
Email: [email protected], Ph: (614) 292 5063
Source: Chapter 11 – Electro-mechanical
Servo-Drive Presses in “Sheet Metal Forming, Fundamentals”,
Vol. 1, by Altan/Tekkaya, ASM International, www.asminternational.org
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