influence of temperature changes on a linear motion system · influence of temperature changes on a...
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Influence of temperature changes on a linear motion system
Jonathan Abir, Paul Shore, Paul Morantz
Laser Metrology and Machine Performance (LAMDAMAP) 2015
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Research overview
• Design and control of a compact linear motion system for high dynamic performance
• Lightweight structure
• High ratio of moving mass to static mass
• Structural flexibility
• Low damping
• The linear motion system characteristics:
Thermal distortion
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What is the linear motion system?
Slave side guideway
Master side guideway
Carriage
Encoder
491mm
609mm
215mm
• Main material - Aluminium
• Guideways material - Alumina
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Bearing arrangement
Slave side
Master side
Roll
Pitch
Yaw
Z
X
Y
• Over constrained design - Roll
• Symmetric design
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Aluminium 6061
Alumina AD 96
Inverse
specific
stiffness
ρ∙E-1 [s2∙m-2]∙10-6
0.39 0.12
Expansion/
conductivity
α∙λ-1 [m∙W-1]∙10-6
0.14 0.24
Inverse
diffusivity
ρ∙Cp∙λ-1
[s∙m-2]∙10-6
0.01 0.5
CTE α [µm/m·°C]
23.6 @ 23-100 °C
6 @ 25-200 °C
Material properties
Alumina Guideway
Aluminium Frame plate
Lower values – superior material
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Why using Alumina guideways?
FEM simulation @ Free-Free boundary condition
Improving dynamic performance
Mode #
Frequency [Hz] Aluminium guideways
Alumina guideways
Improvement
1 107 103 -4 2 122 134 12 5 361 395 34
8 551 582 31
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What is measured?
Thermal distortion of: guideways and frame
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Where it was measured?
Leitz PMM-F CMM
1.9 ( / 400)
@18 22
MPE L m
C
3000mm
1000mm
2000mm
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Component on a CMM
Measured component
Coordinate Measuring Machine
Three points support
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Heating the component on a CMM
Measured component
Coordinate Measuring Machine
Three points support
Heat sources
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Insulating the CMM
Measured component
Coordinate Measuring Machine
Three points support
Heat sources
Reflection and insulation materials
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Measured component
Reflection and insulation materials
Three points support
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Heating source - lamps
Measured component
Reflection and insulation materials
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Measurement at ambient temperature (reference)
Reference measurement
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Response to applied heat
Reference measurement
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Turning off the heat sources
Reference measurement
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Measurements at elevated temperature
Reference measurement
Measurements at elevated temperatures
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Reference measurement
Reference measurement
Measurements at elevated temperatures
Measurement at ambient temperature (2)
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Reference measurement
Aluminium restraint bar
Alumina guideway
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Aluminium restraint bar
Alumina guideway
Applying heat – lamps
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Measurement(s) at elevated temperature
Aluminium restraint bar
Alumina guideway
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“Bottom up” methodology
Alumina Guideway Aluminium restraint bar
Alumina Guideway
Alumina Guideway
Aluminium Frame plate
D. Distortion of full assembly
A. Expansion of single component B. Bending of two components bolted together
C. Bending of Three components bolted together
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24.32[µm/m·°C] (23.6 [µm/m·°C])
5.72 [µm/m·°C] (6 [µm/m·°C])
Aluminium plate
Alumina Guideway
Linear expansion of single component
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FEM and measurements of two components bolted together
Aluminium restraint bar
Alumina guideway X
Y
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FEM and measurements of three components bolted together
X
Y
Aluminium frame plate
Aluminium restraint bar
Alumina guideway
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Flatness measurements at different temperatures of three components bolted together
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Measuring the thermal distortion of full assembly
Schematic view of bended guideways
Slave side guideway
Master side guideway
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Flatness measurements of slave and master guideways
Summary:
•Thermal distortion can be measured using a CMM
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•Thermal distortion can be measured using a CMM •Heating a component on the CMM requires: Thermal insulation
Temperature monitoring •A “bottom up” methodology improve the measurements confidence •The setup allows a repeatable measurement process
•Thermal distortion can be measured using a CMM •Heating a component on the CMM requires: Thermal insulation
Temperature monitoring
•Thermal distortion can be measured using a CMM •Heating a component on the CMM requires: Thermal insulation
Temperature monitoring •A “bottom up” methodology improve the measurements confidence
Future work:
•Measuring the dynamic performances •Developing a compensation method for the structural flexibility •Improving the servo bandwidth, settling time, position error
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