Diapositiva 1

ASTRONOMY AND RESEARCH

July 23rd 2008 VST Meeting

VST ProjectPrimary Mirror Support System

Progress Meeting

Villafranca, July 23rd, 2008

July 23rd 2008 VST Meeting

The supply of the M1 Support System includes:

• Axial force actuators

• Axial fixed point actuators

• Astatic levers

• Lateral fixed points

• Absolute M1 Measuring System

• Safety devices

• Harness

• Prototypes of all devices

• Performance tests

• Subsystems integration on the M1 cell

• M1 Support System testing

• Integration of Auxiliary Units

• Documentation

July 23rd 2008 VST Meeting

The Executive Design of the Axial Force Actuators, the Axial FixedPoints, the Astatic Levers and the Lateral Fixed Points, has beendelivered after approval, while the final design of Safety Deviceswill be carried out after the completion of the analysis forearthquake.

The related Harness has been defined for the most part, and cableshave been purchased.

The first lot of 42 actuators has been assembled and tested withperformances within requirement.

One prototype of the Axial Fixed Points, of the Astatic Levers and ofthe Lateral Fixed Points, has been tested, modified wherenecessary. They all passed the tests on the related test bench andare now ready to be produced.

The Mirror Cell, the Dummy and the Rotation System are in ourfacilities. The crane to perform the integration will be delivered tous within the first days of August.

July 23rd 2008 VST Meeting

PROGRESS SUMMARY

AXIAL FORCE ACTUATOR

July 23rd 2008 VST Meeting

The first 42 Axial Force Actuators have been tested and they allsatisfy the requirements and particularly:

- Maximum force range up 400 N can be obtained also when thesphere 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 supplies400 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

July 23rd 2008 VST Meeting

July 23rd 2008 VST Meeting

Load-displacement diagram (e.g.)

July 23rd 2008 VST Meeting

Performance Test diagram (e.g.)

July 23rd 2008 VST Meeting

42 Axial Force Actuators assembled and tested

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July 23rd 2008 VST Meeting

Items to assemble the next 42 Axial Force Actuators

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In June one prototype of the Axial Fixed Point has beenassembled and tested on the appropriate test bench.

Some changes have been brought because the stiffness hasbeen measured to be less than the required value 9000 N/mm(Ref. NCR-VST-TOM- 009) and they are:

a)Only one piece between the springs and the load cell

b)Massive sphere

c)Steel pieces instead aluminium

- Measured stiffness is now 13300 N/mm

- Passive stroke 3.2 mm with maximum load less than 1500 N

- Preload between 580 N and 700 N

Accuracy has not been measured because the related softwareis not yet available but it has been verified that the two LVDTsmeasure the axial position with the required accuracy.

July 23rd 2008 VST Meeting

AXIAL FIXED POINT

July 23rd 2008 VST Meeting

July 23rd 2008 VST Meeting

Axial Fixed Point on the Test Bench

July 23rd 2008 VST Meeting

In June one prototype of the Astatic Levers has been assembledand tested on the appropriate test bench.

Some changes have been done because it was found that theaccessibility for calibration was difficult (Ref. NCR-VST-TOM-008).

Therefore the following changes have been done:

a)Adjusting and locking the left-right screw by means of axialscrews and special tools

b)Locking of the counterweight by means of fork key

Accessibility is now guaranteed.

Performance achieved:

- Accuracy better than + 5 N

- Force adjusting range over 50 N

ASTATIC LEVER

July 23rd 2008 VST Meeting

July 23rd 2008 VST Meeting

July 23rd 2008 VST Meeting

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The previous solution

The new solution

July 23rd 2008 VST Meeting

Astatic Lever on the Test Bench

July 23rd 2008 VST Meeting

Dummy to test accessibility

In June one prototype of the Lateral Fixed Points has beenassembled and tested on the appropriate test bench.

No change was required apart from the foreseen adjusting ofthe preload of the joint.

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

LATERAL FIXED POINT

July 23rd 2008 VST Meeting

July 23rd 2008 VST Meeting

July 23rd 2008 VST Meeting

Lateral Fixed Point on the Test Bench

Load-displacement diagram

July 23rd 2008 VST Meeting

Before proceeding with the final design of the Safety Deviceswe are waiting for the verification results by BCV and thedecisions by INAF.

If necessary, it is possible to add 2 safety devices at the East andWest positions, working axially on the top side and on thebottom side as well as on the lateral sides with two pads.

Such devices can be brought back c.ca 100mm so to avoid anyinterference with the mirror handling.

The two extra devices are foreseen to be moved from anaccessible location; from this same position it is possible toadjust the backlash with the mirror when desired.

SAFETY DEVICES

July 23rd 2008 VST Meeting

July 23rd 2008 VST Meeting

The preliminary diagrams of the harness have been completedand in July cables and connectors, fulfilling the standard ESO,have been purchased, while the distribution boxes andrepeaters have been delivered to us.

Now with the mirror cell in our facilities the accomodation ofthe cables can be defined and carried out, and particularlycabling support shall be defined.

HARNESS

July 23rd 2008 VST Meeting

The system integration and test activities of M1 cell will beperformed at our facilities in a dedicated area.

A crane, 3 tons capacity and 4 m radial stroke, equipped withnon standard gearboxes to have a velocity of 1 m/min, will beinstalled.

The handling of dummy is foreseen to be done by threeadjustable tie rods and moved by a Hydra-set.

The accuracy of mirror cell and of the dummy will be verifiedby two different articulated arm measuring machines ( Spazio5000 and Metris 3000 ), both certificated.

Particularly it will be verified if the position of the threadedbores is accurate enough to allow measurements related to thedirection of the astatic levers in relation to the mirror.

From the first rough measurements the dummy has the somedimensions as the real mirror and the dimensions of mirror cellis accurate enough.

July 23rd 2008 VST Meeting

INTEGRATION AREA

Integration Lay-Out

June 5th 2008 VST Meeting

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Fondation ready to accept the crane

July 23rd 2008 VST Meeting

Mirror cell on supports during the first verificationsverified

July 23rd 2008 VST Meeting

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Dummy on three supports ready for verification

July 23rd 2008 VST Meeting

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July 23rd 2008 VST Meeting

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Handling for dummy

Support and Rotation System

July 23rd 2008 VST Meeting

Gear and Shafts for the Rotation System

July 23rd 2008 VST Meeting

All procedures for mounting , adjusting , maintenance of allsubsystems after the integration in the Support System areunder definition, as well as the test procedures of the wholeSupport System.

At the moment the complete procedure for the integration andcalibration of all subsystems has been prepared, and togetherwith the procedures to mount and dismount the dummy in themirror cell are ready to be submitted to INAF.

A complete list of these procedures is available.

It is also foreseen to perform accessibility tests to all operations,as for adjusting and maintenance the M1 Support System in realconditions, by simulating the effective encumbrances.

At the moment it has been decided to adopt special tools toallow access to eight astatic levers during mounting andcalibration.

INTEGRATION PROCEDURES

July 23rd 2008 VST Meeting

Procedures list

Axial force actuator assembling

Axial Fixed Point assembling

Astatic Lever assembling

Lateral Fixed Point assembling

Safety Devices assembling

Verification of the mirror cell and dummy

Dummy assembling

Integration of the Axial Actuators

Integration of the Astatic Levers

Integration of the Lateral Fixed Points

Intagration of the Safety Devices

Integration of the Absolute Transducers

Mounting and dismounting of Dummy

Integration of Harness

Verification and calibration of the Astatic Levers

Verification and adjusting of the Safety Devices

July 23rd 2008 VST Meeting