Heinrich Schwenke - CIMi2010, Porto, Portugal Motivation Geometry errors The LaserTRACER TRAC-CAL for Error Mapping and Compensation TRAC-CHECK for Accuracy Testing Current developments Conclusions Rapid Calibration and Compensation of CMM and Machine Tools: Recent Developments of the Lasertracer Technology Accuracy for CMMs and Machine Tools For CMM and machine tools accuracy is a key performance feature Highest accuracy cannot be achieved economically without numerical compensation While for CMMs full error compensation is used for 15 years successfully, it is now introduced in the machine tool world Classical methods for error mapping are time consuming and need operators with years of experience 5 axis machining introduces additional requirement for geometric accuracy Systematic machine errors Geometry deviations of a Cartesian Machine Notation according to VDI 2617-3 (source: PTB) The ETALON solution TRAC-CAL LaserTRACER TRAC-CAL ® TRAC-CHECK ® Error mapping and compensation Testing and qualification Interferometer with 0,001 µm resolution (1) Patented reference sphere (2) with form deviation < 0,050 µm Environmental compensation for temperature, pressure, humidity Length measurement uncertainty: U= 0.2 µm + 0.3 µm/m The LaserTRACER
Transcript
Heinrich Schwenke - CIMi2010, Porto, Portugal
� Motivation
� Geometry errors
� The LaserTRACER
� TRAC-CAL for Error Mapping
and Compensation
� TRAC-CHECK for Accuracy Testing
� Current developments
� Conclusions
Rapid Calibration and Compensation of CMM and
Machine Tools: Recent Developments of the Lasertracer Technology
Accuracy for CMMs and Machine Tools
� For CMM and machine tools accuracy is a key performance feature
� Highest accuracy cannot be achieved economically without numerical compensation
� While for CMMs full error compensation is used for 15 years successfully, it is now introduced in the machine tool world
� Classical methods for error mapping are time consuming and need operators with years of experience
� 5 axis machining introduces additional requirement for geometric accuracy
Systematic machine errors
Geometry deviations of a Cartesian Machine
Notation according to VDI 2617-3 (source: PTB)
The ETALON solution
TRAC-CAL
LaserTRACER
TRAC-CAL ® TRAC-CHECK ®
Error mapping and
compensationTesting and qualification
� Interferometer with 0,001 µm resolution (1)
� Patented reference sphere (2) with form deviation < 0,050 µm
� Environmental compensation for temperature, pressure, humidity
� Interferometrical length measurement from 4-6 positions
� Evaluation of all errors entirely based on length information
� Position of LaserTRACER position and dead path need not be known
The Principle:“GPS-
Principles”
for machine
calibration
∆=
⋅
0
*
00
0L
L
Par
B
CM
[ ] LL
ParCM ∆=
⋅
0
0
*
( ) MKPdCT
Norm
T
par =⋅∆⋅*
EParC par =⋅
( ) TT
Norm LKEPd ∆=⋅⋅∆
( ) TT
parNorm LKParCPd ∆=⋅⋅⋅∆ **
Mathematics
Solving a linearized set of equations
Animation TRAC-CAL Movie TRAC-CAL Software for error mapping
Evaluation of parametric errorsComparison Vertical Machining center: Bevor and after compensation Comparison Horizontal Mill: Bevor and after compensation (Siemens)
www.etalon-ag.com
Comparison Middle Class Vertical Mill: Before and after compensatin (Fanuc)Comparison High End Vertical Mill: Bevore and after compensation (Fanuc)
Horizontal machining center before and after compensation
Summary Error Mapping with TRAC-CAL
� Highest accuracy
� Position, straightness, pitch, yaw, tilt, squareness: All solely based on the wavelength of a stabilized laser
� Suitable for error mapping of CMMs and machine tools
� Applicable for any size of working volume
� Fast execution (1-3 h)
� Simple setup and data handling
� Interfaces and error mapping format for many Controls/CMMs available (and library is expanding)
Siemens Volumetric Compensation
System
for machine tools (VCS)
� Etalon software directly generates volumetric compensation data for
SIEMENS Sinumerik controllers
� Compensation using ETALON technology was tested by Siemens on
various machines
� Etalon has become Siemens Solution Partner in April 2008
Etalon is Zeiss Business-
Partner for Compensation
of CMM
� Zeiss employs Etalon technology for the calibration of different product lines
� Zeiss certifies the Etalon format for customers and service providers
� Zeiss cooperates with Etalon in the further development of Etalon technology
Cooperation with other machine
tool controller manufacturers
� Fanuc und Heidenhain have opened up there controllers for Etalon technology
� Close cooperation with Heidenhain (Heidenhain also has purchased a system)
� Increasingly good cooperation with Fanuc
The ETALON solution
TRAC-CAL
LaserTRACER
TRAC-CAL® TRAC-CHECK ®
Error mapping and
compensationTesting and qualification
Machine Testing with TRAC-CHECK
Principle:
The LaserTRACER operates in “Static Interferometer Mode” but the measurement
direction is automatically aligned by machine motion
� Laser displacement measurement in any direction without manual alignment
� No cosine error
� Data evaluation according to ISO 10360 (CMM) or ISO 230 (machine tools)
Principle TRAC-CHECK Summary Machine Testing with TRAC-CHECK
� Highest accuracy
� Semi-automated execution
� No alignment of interferometer required
� Fast execution: Full geometry test in 30 minutes
� Complete report function satisfying highest traceability demands
� For CMMs: In accordance with latest revision of ISO 10360-2
� For Machine Tools: Testing according to ISO 230-2 and 6
The ETALON solution
TRAC-CAL
LaserTRACER
TRAC-CAL ® TRAC-CHECK ®
Error mapping and
compensationTesting and qualification
63 mm
Reflection angle: +-80°
Uncertainty: U=0.2 µm
Mass: 94 g
Limitation R < 2.5 m
New 160° Cateye
Development focus 1: Measurement “On the Fly”
Measurement of rotary axes: Animation
Tilt error EAC
[µra
d]
−20
−10
0
1000 200 300Angular position [°]
Tilt error EBC
[µra
d]
1000 200 300Angular position [°]
−10
0
10
Position error ECC
[µra
d]
1000 200 300Angular position [°]
0
10
[µm
]
Radial error motion EXC
1000 200 300Angular position [°]
−2
0
Radial error motion EYC
[µm
]
1000 200 300Angular position [°]
−4
−2
0
[µm
]
Axial error motion EZC
1000 200 300Angular position [°]
−2
0
Real-time Multilalateration System
Characteristics:
� Self-calibrating
� Sub µm accuracy
� 1 Nanometer resolution
� 32 kHz bandwidth
Applications:
� Mobile metrology for large
high end parts (PTB)
� Thermal and dynamic
analysis of machine tools
(Fraunhofer)
Source: PTB
Multilaterationsnetz
Test installation
in a laboratory
� Moving reflector
� Multilateration net
of
4 LaserTracer
� Comparison of
spatial points
Source:
PTB
Multilaterationsnetz� Comparison: CMM – Multilateration system
0
200
400
600
800
-400
-200
0
-800
-600
-400
-200
0
X-axis
differences CMM - M3D3 (bestfit)
1 µm
Y-axis
Z-a
xis
0 50 1000
1
2Deviations of positions
[µm
]
0 1 20
10
20
[µm]
0 200 400-0.1
0
0.1Residuals M3D3
[µm
]
-0.1 0 0.10
100
200
[µm]
Source:
PTB
Summary
� With tracking interferometers GPS principles can be applied to CMM and machine tool calibration
� Volumetric compensation of machine tools is on its way to a standard procedure for high end machine tools
� Limiting factors for geometric accuracy of compensated machine tools are- temperature stability of the environment- heat load from machining process - repeatability of the machine (including backlash)- stability of the foundation
� Volumetric accuracy improvements between 50% -80% can be achieved by volumetric compensation of 3 axis machine tools
� “On-the-fly” interferometric tracking can reduce time for a complete error mapping down to 1 hour
� Real time multilateration system open up new approaches for research and 3D metrology
