pre-alignment status
DESCRIPTION
MDI meeting, 16/03/2012. Pre-alignment status. SUMMARY Pre-alignment of the BDS components Latest news from other studies. Active pre-alignment of the components. Requirements. - PowerPoint PPT PresentationTRANSCRIPT
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H. MAINAUD DURAND
on behalf of the CLIC active pre-alignement team
Pre-alignment status
MDI meeting, 16/03/2012
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SUMMARY
Pre-alignment of the BDS components
Latest news from other studies
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Active pre-alignment of the components
Requirements
Because of the very tight tolerances, taking into consideration the temperature effects, ground movements,… and the number of components to be pre-aligned such a pre-alignment must be active:- Determination of the position
by sensors- Adjustment by movers.
The radius of the cylinder corresponds to the total error budget in the determination of the position of components.In the BDS area, this radius equals to 10 μm rms for all the components over 500 m.
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Active pre-alignment of the components
What does this mean?
The determination of the position of the component can be divided (as an approximation) into two steps:
Determination of the “zero” of the component • In the referential frame of its mechanical support• In the referential frame of the sensor
Determination of the position of the referential frame of the sensor coupled to the component w.r.t a stretched considered as a straight reference
Step 1
Step 2
Step 2Step 1
Magnet
Mechanical support
Sensor referential frame
Straight reference
WPS
WPS
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Active pre-alignment of the components
Determination of the zero of the object: status and next steps
Zero = mechanical axis of the component best solution = CMM if the length of the components and their support is not too long
Zero = magnetic axis best solution = CMM
Measurement of this magnetic axis using a vibrating wire, in a CMM, with the support, the quadrupole and the sensors interfaces.
Next step: development of a mock-up to be tested in the Leitz CMM.
Step 1
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Active pre-alignment of the components
Determination of the zero of the object: status and next steps Step 2
Vertical rms error of 11 μm
Radial rms error of 17 μmFaults/problems identified and solved:
• Linearity problem on the sensors (calibration bench)
• Ceramic spheres unglued
But not enough sensors available new sensors ordered (delivery foreseen mid May)reinstallation in TT1 not before August).
Other improvements identified: determination of the deviation of vertical, correction of lunar/solar tides,…
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SUMMARY
Pre-alignment of the BDS
Latest news from other studies
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Study of cam movers
The 5 DOF mock-up is ready
Program of study
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Monitoring of QD0
Latest results : status
First tests concern the assembly of 1m long zerodur rods
Tests of repeatability during the dismounting/mounting spokes and on temperature effects performedo Repeatability < 0.1μmo Temperature effects coherent with expansion coefficient of granite table on
which the spokes are fixed. Next steps foreseen on relative displacement of the 3 spokes.
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SUMMARY
Pre-alignment of the BDS components:
We work in parallel on two steps, trying to gain microns:• Determination of the zero of the component w.r.t the reference frame of
the support and the sensor• Determination of the reference frame of the support w.r.t. stretched wire,
considered as the straight reference of alignment.Results foreseen this summer.Please keep the components as small as possible!
Cam movers: the facility is now operational
Latest news from NIKHEF: repeatability on the contact between the end of the spoke and the reference ring below 0.1 μm, which was the target.