Transcript ppt
GLAST LAT Project
Pisa 9/1/04
GLAST Large Area Telescope:
Gamma-ray Large
Area Space
Telescope
Grid interface proposal
Alessandro Brez
INFN Pisa
A.Brez
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GLAST LAT Project
Pisa 9/1/04
Last failure
The last vibe test failed essentially because:
1) The tolerance between screw shoulder and grid hole was too
large (~0.1mm)
2) The screwed part was too short (~3mm)
3) The steel shoulder damaged the Al hole
Result: the 4 corner screws were unlocked
Al
4.95mm
thread
A.Brez
¼”
Ti
¼”+1mil
Steel screw
with shoulder
¼”-3mils
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GLAST LAT Project
Pisa 9/1/04
Proposal
1) The tolerance between screw shoulder and flexure/grid hole has
to be tight on long
2) The grid has to be reinforced with an insert that distributes the
load on a larger diameter.
We consider the idea to have the tight tolerance by construction even
on few points (3) dangerous, we can have real problems mounting
all the towers (3X16 joints). The possibility to have a failure
mounting one tower cannot be excluded.
In the EM tower, with a simplified coupling (cylindrical holes ¼”) we
could mount the tower to the grid because there was a 0.1mm
tolerance in the shoulder-hole coupling
A.Brez
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GLAST LAT Project
Pisa 9/1/04
Our concept
To guarantee a safe and symmetric joint we propose to separate
the alignment points from the joint points.
1) Mount the alignment jig to the
bottom tray
2) Dry test
3) Put the inserts with epoxy
4) Align back the tower to the grid
5) Place the screws,
RT cure of the adhesive
6) Final torque of the screws,
alignment tool is removed
A.Brez
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GLAST LAT Project
Pisa 9/1/04
Alignment tool
Reference points 3
(the same reference
points used for
sidewall mounting)
A.Brez
The alignment tool is mounted
on the bottom tray using the
bottom tray reference holes
and the M2.5 threaded holes
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GLAST LAT Project
Pisa 9/1/04
Reference to the grid
On the grid there are 3 other
reference holes. The pin/hole
tolerance can be 20mm without
mounting problems (3 points)
A.Brez
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GLAST LAT Project
A.Brez
Inserts
Pisa 9/1/04
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GLAST LAT Project
A.Brez
Pisa 9/1/04
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GLAST LAT Project
Pisa 9/1/04
The inserts
A.Brez
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