Lav meetingF. Raffaelli

INFN – Sezione di PisaC. Capoccia LNF, A. Cecchetti

INFN – Sezione di Frascati

CERN, Dec13th, 2011

-Feet friction studies.-Installation procedure.

2CERN 13/12/2011

Feet friction studies

To validated the design of the LAV feet Cesidio and the Frascati group made a setup to study the friction coefficient.

Different materials and arrangements were considered.

1)Description of the setup

2)Various configurations analyzed

3)Concerning the rigidity of the Lav respect to the restrain configuration.

3CERN- 13/12/2011

Description of the setupA testing frame was made allowing the loading of one single foot.The total weight load is distribuite 0.773 on the foot and 0.227 on the rolling cylinder. To reduced the pushing force a unfavorable leverage was made.

4CERN- 13/12/2011

Description of the setupThe rotational stand was used as fixed shoulder.Two concrete block canb be positioned on the test structure. (each 1120Kg)

5CERN- 13/12/2011

Various configurations were analyzed

Expected friction coefficient depending on a specific pressure

1) Reduced sliding material contact with chromed steel

6CERN- 13/12/2011

Various configurations were analyzed

2) Anular sliding surface contact with chromed steel

3) Anular sliding surface contact with black teflon

The washer is a commercial item

7CERN- 13/12/2011

Various configurations were analyzed

4) Anular sliding surface contact with white teflon

5) Anular sliding surface contact with stainless steel roughness <0.8

8CERN- 13/12/2011

Various configurations were analyzed

6) Anular reduced sliding surface contact with stainless steel roughness <0.8

Results are in accord with the material characteristic. The friction coefficient is decreasing as we increase the contact pressure.The best results in term of friction coefficient are obtained with the case 6.However we notice that the sliding surface of the material has been wear. This is due to the fact that the quantity of material in contact is very small and part of this is remaining in the roughness of the contact surface. So a good result is also the case 5 in which friction coefficient is maintained bellow 0.05 and it has a vantage that we do not have to machined the sliding material to reduced it. The case 3 and 2 with the contact surface in teflon have a similar results of case 5 in term of friction coefficient but we consider less reliable because two soft surfaces in contact tend to glue in time.

9CERN- 13/12/2011

Concerning the rigidity of the Lav respect to the restrain configuration

The supporting system of the vacuum line of NA62 is made of a lot of rigid supports.In order to guarantee that the expected reaction are obtained at the beginning and maintained in time we have to make a good planarity contact surfaces. The supporting needs to be stable in times or move of the same amount in all regions. Furthermore the vacuum sections must not changed their geometry. The redistribution of the reaction will occurs between elements in the case of floor or vacuum sections geometries changes in time. The supports their self must be adjustable and the load transfer to the feet must be done correctly.

10CERN- 13/12/2011

Installation procedure

1) Preparation of the feet contact surface2) Leveling the Lav3) Approaching the Lav to blue tube4) Feet adjusting5) Connecting the LAV to the fixed end to the blue tube6) Connecting the sliding end.

Starting point: the blue tube is the reference element for the LAV installation

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Preparation of the feet contact surface

Composite concrete has been inserted bellow the feet for leveling the contact pads (low shrinkage) 24 hour setting time

12CERN- 13/12/2011

Leveling the LavANTI-1 Handling test to simulate Dis/Installation

Winch to Clock Anti-1

Winch to level Anti-1

Anti-1 Levelling

Anti-1 Clocking

40 mm

From Sliding Connection we get around 40 mm of free space to pull out the Anti-1 from Blu tubes.

It means that we need to level the Anti-1 very fine before to lift it.After, to simulate the installation, we will need to level and also to clock it to get a fine alignment between flange-holes to put in place

few screws to simulate the connections...

C.Capoccia 04.12.2009

Four reference holesCan be used to check the LAVleveling

13CERN- 13/12/2011

Approaching the Lav to blue tube and feet adjusting

1) We make the LAV flange parallel to the blue tube leaving 2 mm gap2) We use two pins in the horizontal plane to make the two flanges concentric.3) We make dial indicator between the two element to check that during the transfer load between the crane to the feet supports.

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Connecting the LAV to the fixed end to the blue tube

We tight the screw zeroing the 2 mm gaps with a proper tightening sequence.The presetting of the 9mm viton cord is on the order of 8 Ton. The extra torque will be used to make in contact the two flanges.During this operation the Lav is going to move on the sliding pads and is been guided by the two horizontal pins.

15CERN- 13/12/2011

Connecting the sliding end

We check that during the sliding ring setting only itself is moving. So a proper tightening sequence is implemented.

16CERN- 13/12/2011

Conclusions

•The tests done on the sliding feet has been frozen the design allowing the procurements of them.•The installation procedure has been partially verify previously with the test that was done.•The test shows that was practical.•The new implementation guarantees that we have the expected load transfer on the Lav feet •This procedure does not effect the previous positioning and feet reactions of blue tube.•The Lav feet leveling and their design allow the thermal compensation of +/- 5mm with a low friction coefficient.