tomelleri s.r.l. ® copyright 2007 © astronomy and research september 19th 2008 vst meeting1

Tomelleri S.r.l. ® Copyright 2007 ©

ASTRONOMY AND RESEARCH

September 19th 2008 VST Meeting 1

VST ProjectPrimary Mirror Support System

Progress MeetingVillafranca, September 19th, 2008

2September 19th 2008 VST Meeting

All Design Descriptions and Test Procedures related to the Axial Force Actuators, the Axial Fixed Points, the Astatic Levers and the Lateral Fixed Points, have been delivered also including the Final Design of Safety Devices foreseen to accept both the Teflon with springs and the Elastomer solutions, even though their stiffness and stroke need to be defined as a result of the earthquake analysis. The documents related to Harness will be completed with the As Built after completion of the accommodation of cables into the mirror cell foreseen within September 26. 36 Axial Force Actuators of the second and third rings have been integrated into the mirror cell while all remaining axial actuators have been tested and will be integrated within end September. The assembling and testing of the Axial Fixed Points will be ready before firmware delivery foreseen within end September. The Lateral Fixed Points have been assembled and tested and are ready to be integrated in the mirror cell. The Astatic Levers have been assembled and are being tested and therefore will be ready for the integration.Mirror Cell and the Dummy have been tested, and are positioned under the crane. All procedures for integration and testing of the Support System have been prepared and will be released after approval.


PROGRESS SUMMARY

AXIAL FORCE ACTUATORS


81 Axial Force Actuators have been tested and they all satisfy the requirements and particularly:- Maximum force range up 400 N can be obtained also when the sphere starts at a distance 1.6 mm from the mirror pad- Accuracy is better than 0.3 N with step 1 N.- Passive stroke is at least 3.2 mm when the actuator supplies 400 N, and the force is in any case less than 1500 N- Maximum force rate more than 20N/sec- Axial stiffness 200 N/mm- Maximum current < 0.1 A (nominal value 0.95A)Each actuator is certificated every 0.5 mm with the proper force-displacement diagram. 36 actuators have been integrated into the mirror cell while the remaining are ready for integration.

Axial Force Actuator on the test bench



36 Axial Force Actuators on the Mirror Cell


Axial Force Actuators before integration

The prototype of the Axial Fixed Point has been assembled and tested on the appropriate test bench, and it has satisfied the requirements and particularly:- Stiffness is 13300 N/mm more than 9000 N/mm- Passive stroke 3.2 mm with maximum load less than 1500 N- Preload between 580 N and 700 N Positioning accuracy has not been measured because the related software is not yet available but it has been verified that the two LVDTs measure the axial position with the required accuracy.The firmware to test positioning will be ready within end September.After this all remaining test will be done.


AXIAL FIXED POINTS

Three Axial Fixed Points during assembling

9September 19th 2008 VST Meeting

All Astatic Levers has been assembled and now are being tested.The tested Astatic Levers satisfy the requirements and particularly:- Force accuracy better than + 5 N - Force adjusting range over 50 N- Accessibility for adjusting and mountingAll 24 Astatic Levers will be integrated into the mirror cell within end September. Tests to verify the accessibility to mount and adjust the Astatic Levers, have been foreseen to perform after the mounting in the mirror cell.

September 19th 2008 VST Meetin 10

ASTATIC LEVERS


Astatic Lever on the Test Bench


Astatic levers after assembling

The four Lateral Fixed Points, included spare, have been assembled and tested on the appropriate test bench.Performance achieved:- Preload between from 600 up 800 N in both directions- Stiffness 25000 N/mm (requirement > 20000 N/mm)- Passive stroke 5 mm in all directions- Maximum force on the mirror is 1300 N The three Axial Fixee Points are now ready to be integrated into the mirror cell within end September.


LATERAL FIXED POINTS


Lateral Fixed Points after assembling and testing

The system integration and test activities of M1 cell is being carried out at our facilities in our workshop. A crane, 3 ton capacity and 4 m radial stroke, equipped with non standard gearboxes to have a velocity of 1 m/min, has been installed. The handling of dummy is foreseen to be done by three adjustable tie rods and moved by the Hydra-set.The supports for the rotation system have been prepared to accept the drive system.


INTEGRATION AREA


Mirror cell and Dummy under the crane


Handling for Dummy before Hydra-Set supply

September 19th 2008 VST Meetin 18

Rotating support modified for the drive system

• Testing of accuracy of the mirror cell: measures have shown astatic levers interface, M8 holes and derotator interface are within + 0.1 mm, while the interfaces to actuators have been corrected by the flanges height

• Adjusting and testing of the axial actuators interface within + 0.1mm, and the height of the sphere of the 36 actuators is within + 0.1 mm

• Testing of the dummy: on the first and second ring the height is within 0.1 mm, on the third and fourth ring 0.2 mm; lateral pads within 0.2 mm.

• Reworking of the mirror cell. Threaded holes to apply the lateral fixed points, safety devices and absolute transducers will be referred to the exixting threaded holes, and will be done (within end Sept. )

• The pads under the dummy will be applied (within end Sept. )• Completion of the axial actuators integration and height verification (end Sept.)• Lateral fixed points integration (within end Sept. )• Astatic levers integration(within end Sept. )• Absolute transducers integration(within end Sept. )• Integration of dummy in the mirror cell foreseen to be done at 10 October• Safety devices will be integrated within November 8 with Teflon pads


Integration Procedures

Mirror cell testing


Dummy testing


Flange height verification


Integration of some axial actuators


Height of the actuators


Testing of the height of the Axial Force Actuators


The diagrams of the harness have been completed, while the as-built drawings will be prepared within September 26.All power connection to the actuators have been done with the proper accommodation under the mirror cell, while the Can Bus will be connected within September 26.Distribution boxes and the repeater box have been fixed to the mirror cell ready for connection.


HARNESS

Testing of axial actuators connected



Power cables to connect to all axial actuators

The design of the mechanical supports of the safety devices have been completed and they foresee to accept both Teflon pads with springs and Elastomer pads.The safety devices include:- 16 upper axial safety devices- 14 lower safety devices- 18 lateral safety devices- 2 special lateral safety devices, in the East and West positions, that can be moved away from an accessible location.In order to get the safety devices ready for mirror demounting it is enough to rotate the upper part of the safety devices and bring the supports back ca 10 mm, so to avoid any interference with the mirror and with the handling.Four safety devices need to be demounted. Repositioning doesn’t require any backlash adjusting. September 19th 2008 VST Meeting 29

SAFETY DEVICES


Safety devices general view

Safety devices general assembly


Safety device in East-West positions


Safety device lateral view


Teflon pads with springs:- Shorter delivery time- Lower costElastomer pads:- Better pressure distribution- More damping- Smaller encumbrancesWe have had a meeting at Exsto facilities in France in order to answer all questions. All requirements seem to be satisfied, that will be confirmed in written form: stability, amount of permanent deformation, linear behaviour, two different kinds of elastomer. With the Elastomer solution the test on the mirror cell on the rotation system will be done with Teflon pads without springs. The elastomer pads will be tested in our facility before sending them to Paranal.


Teflon-spring pads vs. Elastomer


Eladip applications

June 5th 2008 VST Meeting 36

Eladip stiffness

TEST PROCEDURES AFTER INTEGRATIONTest Procedures phase 1.A


Integration Test Phase 1-A: tests at ground with the M1 Mirror Cell that lays horizontally on the four supports and before Dummy Integration • T1. Geometry of the Axial Actuators (both Axial Force Actuators and Axial Fixed Points)• T2. Reading of the Absolute Transducers• T3. Software-Hardware Communication• T4. Axial Actuator Manual Control System

Detailed procedures are available in the proper document

Test Procedures phase 1.B


Integration Test Phase 1-B: tests at ground with the M1 Mirror Cell that lays horizontally on the four supports and after Dummy Integration

• T5. Geometry Test of the Lateral Fixed Points• T6. Geometry Test of the Astatic Levers• T7. Radial Dummy stroke • T8. Load Control of the Axial Force Actuators• T9. Accessibility to all devices for Maintenance

Detailed procedures are available in the proper document

tomelleri s.r.l. ® copyright 2007 © astronomy and research september 19th 2008 vst meeting1

Documents

vst meetingseptember

mirror cell

axial fixed points

remaining axial actuators

axial position

n maximum force rate

vst meetingthe prototype

nsec axial stiffness