year of establishment: 1955 educational philosophy ... · machining resume. amplifier daq...
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CYCU
• Year of Establishment: 1955
• Educational Philosophy: Holistic
Education
• Faculty & staff: 833 (fulltime)
• Students body: 16,600
• Graduate Students: M.S. 3,480,
Doctoral 390
• Alumni: 90,000+
• Programs: 6 Colleges/1 School/27
Departments
• 28 Graduate programs/13 Doctorate
programs
CYCU Profile
CYCU
CYCU Campus
The 10th Canada-Taiwan Conference in Higher Education
3 Precision Engineering Lab, Chung Yuan Christian University
Shih-Ming Wang, Ph.D.
Associate Professor/Vice CEO Department of Mechanical Engineering
Executive Operation Center for Industry-Academia Cooperation Chung Yuan Christian University
Chung-Li, Taiwan 10/17/2012
Background
Principle
Structure of System
Experimental Verification
Conclusions
5
Micro lens array
CYCU 3-axis Toggle-type CNC Micro Machine Tool 5-axis CNC Machine Tool 3-axis CNC Machine Tool
Precision milling plays an important role for manufacturing of high-tech products.
Intelligent system that can on-line detects and controls abnormalities and improve machinng process, can increase machining accuracy & production efficiency for the production line.
High speed
Intelligent
Central manag. ICT gives more opportunities & capabilities
Software enhances hardware，
High accuracy/high speed
Intelligent machine => production line - Accuracy & efficiency ICT plus
ICT-based intelligent system
Machine Machining
• When abnormalities (such as chatter, built-up-edge, and cutter breakage) occur during machining, they will cause
damage on the surface of the workpiece, reduction of tool life, increase of scrap parts and manufacturing cost, low production efficiency
=> Need
additional rework, replacement of tool, overhaul of machine
• An intelligent monitoring/control system that can early
detect/control the occurrence of machining abnormalities has more benefits for production. (Minimize damages)
• Collected machining status and monitoring information can be used for process optimization
2011/7/25 精密工程研究室 Precision Engineering Lab
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Requirements Effective and reliable - efficiency diagnosis and control algorithms
More inside information from machining process and the machine - Direct communication with CNC controller
Remote operation/central monitoring – compatible with internet protocol
Multiple-machine monitoring – Open CNC controller
Approaches: Fast Fourier Transform
Algorithm of short-time signal variation analysis (less computation time)
Bi-lateral direct communication module for Instant machining status (Fanuc Open CNC Api, Focas 2 Library, C#)
ICT-Ethernet protocol Communication (remote login) -
An internet-based high-efficiency diagnosis/control system that can early detect
and activate adequate control process
2011/7/25 9 精密工程研究室 Precision Engineering Lab
On-line Signal Processing
Signal characteristics analysis
Develop diagnosis & control algorithms
Develop bi-lateral communication module
communication
Develop real system
Experimental verification
Characteristics of Signal Variation (forminping area)
Time-domain vibration signals
FFT
vi
brat
ion
Forming
normal
Idle
Chatter freq.
Tool passing freq.
In transition (developing) period, vibration quickly diverges and increases over 2.5 times within 1 second.
Detect the chatter in transition (developing) period
Rule: Increase rate of each
divided signal: 1.254
times or up
Rule: The major vibration
frequency is multiple of
the tool passing frequency.
On-site monitoring system
Connect system and machine through a designed bi-lateral communication module (Open CNC Spec; C#; Ethernet) Transmit vibration signals & machining status information Transmit control commands to adjust spindle speed to suppress chatter
振動加速度規
CNC controller
Instant status info
Control command
Diagnosis 2 Rules
Suppression Adjust spindle speed
Vibration signal collection
Detection: < 1 second; Total: < 3 seconds
2011/7/25 精密工程研究室 Precision Engineering Lab 12
2011/7/25 精密工程研究室 Precision Engineering Lab
13
Large vibration When BUE occurs, the actual tool passing frequency becomes
x (nominal tool passing frequency)
Low frequency vibration after BUE formed
14
N60
SNominal tool passing freq.(Hz)
S:spindle speed, N: No. of edges; A:No. of BUE edges
N
)AN(
Initial vibration, BUE
Low freq. vibration BUE
Vibration due to emergence stop
Nominal tool passing freq.(NTPF)
BUE freq. =3/4 of NTPF
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Instantly stop the machine for tool change
With the bi-lateral communication module
BUE diagnosis
Within 3 seconds
PLC Machine stopped command
CNC controller
Instant large vibration
Minimum vibration after big vibration
Vibration while no cutting
Info. Of cutting trajectory
Abnormal vibraation
machining No vibration
Machining Breakage No machining
time
On-site monitoring/ control
振動加速度規
控制器
Cutting info.
Commands
Diagnosis Two thresholds Trajectory check
Instant machine stop
Signal acqusition
Stop machine for tool change
Total: < 2 seconds
Signal collect & process
•Control info. •Abnormality info. •Machine status
•Abnormality prevention •Machining parameter optimization
Accelerometers
CNC controller
Bi-lateral communication
module
Ethernet
Machine (機台端)
On-site monitoring unit (近端監控系統)
(1) Chatter (顫振) (2) Build-up-edge(刃口積屑) (3) Cutter Breakage(斷刀) (4) Chipping(刀具崩裂)
•Abnormality Diagnosis
• On-line monitoring of Control Parameters Ex. NC code 、feedrate、
spindle speed, currents
Instant information
Control commands
Remote central monitoring platform
(遠端中控平台)
Wireless internet
Process optimization unit
Machining resume
Amplifier DAQ
Multi-machine remote monitoring
Data
Monitoring interface
Central
Signal collection
Machining database
On-site
engineers command
data
加速規
Controller
Diagnosis &
control module
Setup Dignosis Confirmation
On-site
Remote
2011/7/25 精密工程研究室 Precision Engineering Lab 21
Cutting tool Ø12 × 4 etc.(HSS) Workpiece material A6061 T6（aluminium） Cutting path straight line Cutting depth（mm） 4 Cutting width（mm） 6 Spindle speed（rpm） 6000 Feed drive（mm/min） 250 Cutting passing frequency(Hz） 400
Conditions
Cutter Ø12 × 4-flutes (WC)
Material P20（鐵材）
Depth of cut 24 mm
Width of cut 0.8 mm
Spindel speed 8000 rpm
Feedrate 10000 mm/min（max）
Tool passing freq. 533.33 Hz
Suppression Ra Ry Rz
Before 0.90μm 8.16μm 6.06μm
After 0.31μm 2.52μm 2.00μm
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Initial BUE
Low freq. vibration
Machine stopped
Conditions cutter Ø12 × 4 flutes(HSS) Material A6061 T6（Al） D.O.P（mm） 2 W. O. P（mm） 12 Spindle speed（rpm）
12000
feedrate（mm/min）
1000（max）
Nominal tool passing freq.（Hz）
800
¼ of NTPF
2/4 of NTPF
3/4 of NTPF
NTPF
Experiment – BUE
Conditions
Cutter : Ø4 × 2 flutes(WC ball-end mill)
Material: A6061 T6（Al）
Cutting trajectory: straight
D.O.C（mm）: 4
W.O.C（mm）: 4
Spindle speed（rpm）: 3000
feedrate（mm/min） : 450->750
Breakage
2011/7/25 精密工程研究室 Precision Engineering Lab
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High-efficiency Diagnosis Algorithms were developed
Instant Control algorithms with Bi-lateral communication module were developed Practical system which can diagnose the tree
abnormalities simultanenously with friendly interface was developed
The experimental results have shown the effectiveness and reliability of system
2011/7/25 精密工程研究室 Precision Engineering Lab 26