Page 1 © AfM Technology GmbH / Wolfram Meyer
The Engineering & Calibration Service Company
for
Volumetric Compensation of machine tools / CMM Linear and rotary axis calibration of machine tools / CMM
Page 2 © AfM Technology GmbH / Wolfram Meyer
Aachen colloquium for 5-Axis precision machining
Geometric deviations of machine tools
Metrological parameter aquisition
Compensation in the CNC control
Limitations in aquisition and compensation
Trends and challenges
Agenda
Page 3 © AfM Technology GmbH / Wolfram Meyer
Geometric deviations of machine tools
Aachen colloquium for 5-Axis precision machining
Page 4 © AfM Technology GmbH / Wolfram Meyer
Influences on machine tool accuracy
Dynamic
Drives
Thermal influences
Geometry
Component
deviations
Location deviations
Model fitness
Machine coordinate
system
Page 5 © AfM Technology GmbH / Horst Eckersberger
support
guide
Each linear guide has 6 degrees of freedom, 3 translational und 3 rotational
translational movement
(transverse to the guide axis) / EZX
rotational movement:
around X = roll / EAX
around Y = pitch / EBX
around Z = yaw / ECX
translational movement (position) / EXX
translational movement
(transverse to the guide axis) EYX
Geometric deviations on a linear machine axis
Page 6 © AfM Technology GmbH / Horst Eckersberger
support
Rotary table
Each rotary axis has 6 degrees of freedom, 3 translational und 3 rotational
translational movement (axial runout in Z) / EZC
rotational movement:
around X = wobble / EAC
around Y = wobble / EBC
around Z = position / ECC
translational movement (radial runout in X) / EXC
translational movement (radial runout in Y) / EYC
Geometric deviations on a rotary machine axis
Page 7 © AfM Technology GmbH / Wolfram Meyer
Kinematic chain of a machine tool
3 linear axes
3 rotary axes
1 spindle
coordinate system
Effective deviations
t – S – A – B – Y – Z – MB – X – C – MT – w
Kinematic chain
Tool Work piece
Spindle Machine
base
3 x 6 = 18
3 x 6 = 18
1 x 5 = 5
41
3 x 3 = 9
3 x 5 = 15
1 x 4 = 4
- 6
28
∑ = 69 deviations
Component dev. location dev.
© AfM / Keppler
Page 8 © AfM Technology GmbH / Horst Eckersberger
Resulting errors at the tool center point (linear axes)
The geometrical errors of the linear axes of a 3-axes machine tool cause spatial errors of the TCP concerning position and orientation.
Geometric errors
positioning error
straightness
roll
yaw
pitch
squareness
Resulting error at TCP
positioning error
orientation error
Programmed tool position and tool orientation
Real TCP position
Real tool orientation
Page 9 © AfM Technology GmbH / Wolfram Meyer
Resulting errors at the tool center point (rotary axes)
The component and location errors of the radial axes of a 4/5/6-axes machine tool causes also spatial errors of the TCP concerning position and orientation.
Geometric errors
runout
wobble
position
location of axis
orientation of axis
zero position
Resulting error at TCP
positioning error
orientation error
Real TCP position
Real tool orientation
Page 10 © AfM Technology GmbH / Wolfram Meyer
Metrological parameter aquisition
Aachen colloquium for 5-Axis precision machining
Page 11 © AfM Technology GmbH / Wolfram Meyer
Measurement methods for error parameters
Direct Measurement Indirect Measurement
Component
deviations
Location
deviations
Component and location deviations
Laserinterferometer
Straightness artefact
& indicator (Wire /
Stone)
Levels
Reference encoders
Reference scales
Autokollimator
Laserinterferometer
90° stone angle,
calibration cube &
dial indicator
Levels
Test mandrel & dial
indicator
Ball bar, ball plate, Tetraeder
Reference parts
Circular test
Ball & 3D-Probe
Lasertracker
LaserTRACER
Page 12 © AfM Technology GmbH / Wolfram Meyer
Straightness laser
Levels Reference scales
Autokollimator
Straightness artefact & indicator (Wire / Stone)
Direct measurement of linear axis with single-purpose tools
A great variety of tools is used
Page 13 © AfM Technology GmbH / Wolfram Meyer
Direct measurement of linear axis with laser interferometer
Laserinterferometer available with 1 up to 6 DOF
High accurate, long range
Alignment effort, particularly for vertical and
straightness measurement is high
Renishaw (1-DOF)
HP Agilent (1-DOF)
API (6-DOF) TSK (3-DOF)
© TSK
Page 14 © AfM Technology GmbH / Wolfram Meyer
Direct measurement of rotary axis
HEIDENHAIN Reference encoder RON 905
Laserinterferometer with Renishaw RX10 API Swivelcheck
Test mandrell
&
dial indicator
Page 15 © AfM Technology GmbH / Wolfram Meyer
Indirect measurement of linear axis with ball bars
Fast and easy measurement
Geometric and drive analysis
Applicable in any plane
Mind the volume size
Renishaw QC-20W
Dreier RoundCheck VA API Ballbar
Page 16 © AfM Technology GmbH / Wolfram Meyer
Indirect measurement of component and location deviation
© IBS Precision Engineering
Tetraeder
© Prof. Knapp ETH Zürich
Ball bars (1D), ball plates (2D), Tetraeder (3D)
Fixed grid, limited dimension, handling complex
Ball bar
© Dr. Trapet
Ball plate
Page 17 © AfM Technology GmbH / Wolfram Meyer
Indirect measurement of linear axis with laser interferometer
Optodyne MCV 500 © Dr. Trapet
Page 18 © AfM Technology GmbH / Wolfram Meyer
Indirect measurement by multilateration with LaserTRACER
Linear axis calibration
Rotary axis calibration
Acceptance test according
to ISO 230-2/4/6 and ISO
10360-2
LaserTRACER MT LaserTRACER
Page 19 © AfM Technology GmbH / Wolfram Meyer
Online multilateration with LaserTRACER
What is Multilateration?
Ideal realization of the Abbe Principle: All measurement
lines pass directly through the measurement point.
Principle is used in Global Positioning System (based on
time of flight measurement).
With LaserTRACERs, the principle can be downscaled to
submicron accuracy in a medium measurement volume.
If four LaserTRACERs are used, the system is self calibrating
Characteristics
Mobile, Self calibration
Contactless, 3D measure
Working volume up to 10 m x 10 m x 10 m.
Direct traceability by stabilized laser interferometer.
Highest resolution and accuracy (down to sub-micron range)
© Etalon
Page 20 © AfM Technology GmbH / Wolfram Meyer
3D Messung mit LaserTracker
Lasertracker Moving Active Target (AT)
Stationary T3 Laser Tracker (with Pan & Tilt)
© API
Page 21 © AfM Technology GmbH / Wolfram Meyer
Rotary axis calibration with ball and 3D probe
Fork Head Calibration
Trunion Table Calibration
Rotary and swivel axis as well as trunion table are
supported
Fixed ball, moved probe or fixed probe and moved ball
Fast, easy and automatic cycle
Up to 3 rotary axis at once
© HEIDENHAIN © Fidia © IBS Engineering Precision
Page 22 © AfM Technology GmbH / Wolfram Meyer
Compensation in the CNC control
Aachen colloquium for 5-Axis precision machining
Page 23 © AfM Technology GmbH / Wolfram Meyer
Geometric compensations in CNC controllers
Geometric compensations (stand alone or as combination)
Linear encoder error compensation (slope)
Non linear encoder error compensation (arbitrary form)
Cross error compensation
Grid compensation
Volumetric compensation
Stand alone or as part of geometric compensation
Backlash compensation
Page 24 © AfM Technology GmbH / Wolfram Meyer
Linear and non linear encoder error compensation
linear encoder error compensation (slope)
Non linear encoder error compensation (arbitrary form)
-40,0
-20,0
0,0
20,0
40,0
60,0
80,0
100,0
0
200
400
600
800
1000
1200
1400
1600
1800
2000
2200
2400
2600
2800
3000
3200
3400
dev
iati
on
[µ
m]
Position deviation y-axis
yTy / EYY Linear (yTy / EYY)
Page 26 © AfM Technology GmbH / Wolfram Meyer
Cross error compensation
Crosstalk of any axis combination can be compensated
Compensation of straightness and squareness
© HEIDENHAIN
Page 27 © AfM Technology GmbH / Wolfram Meyer
3D Grid compensation
The volume is divided in cubes or a spherical grid
Each corner of the cube is represent by an error vector
Used for linear axis as well as rotary axis
∆Xi ∆Yi = f(A,C) ∆Zi
© Siemens © FANUC
© Bosch Rexroth
Page 28 © AfM Technology GmbH / Wolfram Meyer
Volumetric compensation
E = Te + Rem * Pm + Ret* Pt
Page 29 © AfM Technology GmbH / Wolfram Meyer
Backlash compensation
Backlash compensation As single axis parameter
As data set along the axis
-40,0
-30,0
-20,0
-10,0
0,0
10,0
20,0
-29,0 -24,0 -19,0 -14,0 -9,0 -4,0 1,0 6,0 11,0 16,0 21,0 26,0
Position deviation B-Axis (forward & backward travel)
without CEC [0,001°] with CEC [0,001°]
without CEC [0,001°] with CEC [0,001°]
z.B. Siemens 840D sl
MD 32450 Backlash compensation
$MA_BACKLASH[0]=0.002 mm
Backlash U / U1
Page 33 © AfM Technology GmbH / Wolfram Meyer
Limitations in aquisition and compensation
Aachen colloquium for 5-Axis precision machining
Page 34 © AfM Technology GmbH / Wolfram Meyer
Limitation by model fitness (I)
yTz = yTz(y) + Ytz(y,z) *z
yRx = yRx(y) + yRxz(y,z) * z
EZY = EZY(y) + EZYZ(y,z) *z
EAY = EAY(y) + EAYZ(y,z) * z
Crosstalking from Z-axis to Y-axis
Z
Y
Z
Y
Y
Z
EAY (y,z)
yRx (y,z)
EZY (y,z)
yTz (y,z)
0
100
200
300
400
500
600
700
800
900
21 Error Model
0
200
400
600
800
1000
1200
1400
1600
23 Error Model
±3s ≈ ±18,3 µm ±3s ≈ ±30,6 µm
Page 35 © AfM Technology GmbH / Wolfram Meyer
Limitation by model fitness (II)
-10,00,0
10,020,030,040,050,060,070,080,090,0
100,0
0
200
400
600
800
1000
1200
1400
1600
1800
2000
2200
2400
2600
2800
3000
3200
3400
dev
iati
on
[µm
/m]
Bending of Column
YTZZ with 21 model YTZZ with 23 model
-5,0
0,0
5,0
10,0
15,0
20,0
25,0
30,0
0
200
400
600
800
1000
1200
1400
1600
1800
2000
2200
2400
2600
2800
3000
3200
3400
dev
iati
on
[µra
d/m
]
Yaw of Column
YRXZ with 21 model YRXZ with 23 model
0,000000
1,000000
deviation [µrad]
Squareness yWz / AOZ
yWz/AOZ
yWz/AOZwith 23 model
-25,0
-20,0
-15,0
-10,0
-5,0
0,0
5,0
10,0
15,0
20,0
0
200
400
600
800
1000
1200
1400
1600
1800
2000
2200
2400
2600
2800
3000
3200
3400
de
viat
ion
[µra
d]
Pitch y-axis
yRx / EAY with 21 model yRx / EAY with 23 model
Page 36 © AfM Technology GmbH / Wolfram Meyer
Volumetric Compensation of machine tools
Limitation by volumetric backlash
Volumetric backlash analysis
Position 1 Position 2 Position 3 Position 4 Position 5 Position 6 Total Maximum 0,0187 0,0290 0,0170 0,0271 0,0142 0,0087 0,0087
Minimum -0,0281 -0,0234 -0,0255 -0,0183 -0,0149 -0,0153 -0,0153
Range 0,0468 0,0524 0,0426 0,0454 0,0290 0,0240 0,0240
Std. dev. σ 0,0101 0,0119 0,0089 0,0092 0,0056 0,0061 0,0061
±3σ (99,73%) 0,0607 0,0717 0,0532 0,0549 0,0338 0,0369 0,0369
Drift 0,0000 0,0000 0,0000 0,0000 0,0000 0,0000 0,0000
x ̅ + 3σ 0,0303 0,0358 0,0266 0,0275 0,0169 0,0184 0,0184
Average x̅ 0,0000 0,0000 0,0000 0,0000 0,0000 0,0000 0,0000
x ̅ - 3σ -0,0303 -0,0358 -0,0266 -0,0275 -0,0169 -0,0184 -0,0184
-0,040
-0,030
-0,020
-0,010
0,000
0,010
0,020
0,030
0,040
1 26 51 76 101 126 151 176 201 226 251
Backlash single values
x ̅- 3σ x ̅+ 3σ Pos1 Pos2
Pos3 Pos4 Pos5 Pos6
0
20
40
60
80
100
120
140
160
180
-0,0
300
-0,0
270
-0,0
240
-0,0
210
-0,0
180
-0,0
150
-0,0
120
-0,0
090
-0,0
060
-0,0
030
0,00
00
0,00
30
0,00
60
0,00
90
0,01
20
0,01
50
0,01
80
0,02
10
0,02
40
0,02
70
0,03
00
Backlash distribution
Page 37 © AfM Technology GmbH / Wolfram Meyer
Volumetric Compensation of machine tools
Limitation by temperature conditions
13,0
14,0
15,0
16,0
17,0
18,0
19,0
20,0
21,0
22,0
10:1
5:00
12:0
0:00
13:4
5:00
15:3
0:00
17:1
5:00
19:0
0:00
20:4
5:00
22:3
0:00
00:1
5:00
02:0
0:00
03:4
5:00
05:3
0:00
07:1
5:00
09:0
0:00
10:4
5:00
12:3
0:00
14:1
5:00
16:0
0:00
17:4
5:00
19:3
0:00
21:1
5:00
23:0
0:00
00:4
5:00
02:3
0:00
04:1
5:00
06:0
0:00
07:4
5:00
09:3
0:00
11:1
5:00
13:0
0:00
14:4
5:00
16:3
0:00
18:1
5:00
20:0
0:00
21:4
5:00
23:3
0:00
01:1
5:00
03:0
0:00
04:4
5:00
06:3
0:00
08:1
5:00
10:0
0:00
11:4
5:00
13:3
0:00
15:1
5:00
17:0
0:00
18:4
5:00
20:3
0:00
22:1
5:00
00:0
0:00
01:4
5:00
03:3
0:00
05:1
5:00
07:0
0:00
Temperature over time
X-Achse (min) [°C] X-Achse (max) [°C] Z-Achse [°C] Y-Achse (min) [°C] Y-Achse (max) [°C] Luft [°C]
Calibration
with AC-Head Verification
With AC-Head
Calibration
With AC-Head Calibration
W-Axis
Verification
W-Axis Calibration
With Quill Verification with Quill
Page 38 © AfM Technology GmbH / Wolfram Meyer
Trends and challenges
Aachen colloquium for 5-Axis precision machining
Page 39 © AfM Technology GmbH / Wolfram Meyer
Trends and challenges
Dynamic data collection
Advanced kinematic error models
MPE for volumetric accuracy
Thermal models for machines
Kinematic measurement at once
Online connection
Page 40 © AfM Technology GmbH / Wolfram Meyer
Thank you for your attention
Vielen Dank für Ihre Aufmerksamkeit
Grazie per la vostra attenzione
AfM Technology GmbH
Gartenstraße 133
73430 Aalen / Germany
Fon: +49 (0)7361 889608-0
Fax: +49 (0)7361 889608-99
www.afm-tec.de • [email protected]
AfM Technology Italia Srl
Via Giotto 25 / Giotto Straße 25
39100 Bolzano / Bozen / Italy
Fon/ Fax: +39 0471 911953
Mobile: +39 348 4221124
www.afm-tec.it • [email protected]