Download - GLAST:Gamma Ray Large Area Telescope
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GLASTGLAST GLASTGLAST Pisa GLAST Italia meeting, 18/02/02 A.Brez – INFN Pisa
GLAST:Gamma Ray Large Area Telescope
Ladders, Trays and Towers Construction
A.BrezINFN - sez. Pisa
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GLASTGLAST GLASTGLAST Pisa GLAST Italia meeting, 18/02/02 A.Brez – INFN Pisa
Pre-engineering model tower (2001)Engineering model tower (february-july 2002)Qualification tower17 flight towers (16+1spare)
The pre-engineering tower is now ready and it will be tested next week at SLAC
Construction program
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GLASTGLAST GLASTGLAST Pisa GLAST Italia meeting, 18/02/02 A.Brez – INFN Pisa
Purpose of the pre-engineering tower:1. Experimental validation of the mechanical project (drawings and materials)2. Experimental validation of the tray assembly procedure3. Qualification of the tray producers (PCI California, Plyform Italy)4. Experimental validation of the tower assembly procedure5. Dynamical test of the trays (vibrational)6. Thermal test of the trays7. Dynamical test of the tower (vibrational)
Italian efford:1. superGLAST (W=18%Xo) payload study 2. Production of 4 superGLAST trays3. Tray vibrational test4. Production of 1 GLAST (W=3%Xo) tray
Different procedures of tray and tower assembly have been developed:1. US procedures more close to the BTEM experience2. Italian procedures with more attention to the large series production
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GLASTGLAST GLASTGLAST Pisa GLAST Italia meeting, 18/02/02 A.Brez – INFN Pisa
Hytec tray assembly strategy:Gluing at 120oC face-sheets, honeycomb and closeouts with a monolithic graphite tool.There are problems due to the CTE mismatch between graphite and Carbon-CarbonComplicate tool, hard to control it.
Hytec (Los Alamos- New Mexico) tray assembly scheme developed in collaboration with PCI (Ontario, California)
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GLASTGLAST GLASTGLAST Pisa GLAST Italia meeting, 18/02/02 A.Brez – INFN Pisa
Assembly procedure guideline used in Plyform:Structural gluing of the face sheets with the honeycomb under moderate pressure (0.2atm) at high temperature (Redux 312 UL, 100g/m2 foils, cured at 120oC)Room temperature gluing of the closeouts (Redux 420 AB)References holes used for tray assembly and for subsequent alignments situated on the closeout
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GLASTGLAST GLASTGLAST Pisa GLAST Italia meeting, 18/02/02 A.Brez – INFN Pisa
Walls housing
Face-sheet reference pinholes
Plates reference pinholes
Bars fixing holes
BASE COVER
TRAY ASSEMBLY JIG
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GLASTGLAST GLASTGLAST Pisa GLAST Italia meeting, 18/02/02 A.Brez – INFN Pisa
FEM of the tray assembly jig
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GLASTGLAST GLASTGLAST Pisa GLAST Italia meeting, 18/02/02 A.Brez – INFN Pisa
SuperGLAST tray without payload
The Engineering Model trays will be done with fully Carbon-Carbon closeouts, without the Al particulars
M2.6 thread holes F3 reference holes
M2.6 thread holes
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GLASTGLAST GLASTGLAST Pisa GLAST Italia meeting, 18/02/02 A.Brez – INFN Pisa
0 50 100 150 200 250 300
X=-75mm
"X=+75mm"-0.02
-0.015
-0.01
-0.005
0
0.005
0.01
0.015
0.02
Z(mm)
Y(mm)
X(mm)
tray GALST Plyform 0 bottom side
0 50 100 150 200 250 300
X=-75mm
"X=+75mm"-0.02
-0.015
-0.01
-0.005
0
0.005
0.01
0.015
0.02
Z(mm)
Y(mm)
X(mm)
tray GALST Plyform 0 top side
X=-75mm
X=0mm
"X=+75mm"
Planarity of the GLAST tray #0 produced by PlyformVacuum bag differential pressure = 0.2Atm
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GLASTGLAST GLASTGLAST Pisa GLAST Italia meeting, 18/02/02 A.Brez – INFN Pisa
Tray #2 thermal boss profiles
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0
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500
600
700
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mm
m m
Trey #3 thermal boss profiles
-100
0
100
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300
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500
600
0 50 100 150 200 250 300 350 400
mm
m m
Tray #4 thermal boss profiles
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0
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700
0 50 100 150 200 250 300 350 400
mm
m mTray #1 thermal boss profiles
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mm
m m
CMM measurements of the sides of the tray mean dimensions= 368.589 mmX368.586 mm
+0.038-0.034
+0.066-0.037
*** WBS 4.1.4 TRACKER (R. Johnson)
TKR Mechanical * The stacking test and measurements on the PCI carbon-composite trays showed that the jigging as used at PCI did not hold the dimensional tolerances sufficiently well. Those trays will be machined slightly to fix them up for further tests.* The room-temperature cure method and jigging used at Plyform (the intended fabrication vendor for engineering model and flight panels) does appear to hold tolerances sufficiently well, based on 3 trays measured.----------------------------------------------------------------
MCM side
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GLASTGLAST GLASTGLAST Pisa GLAST Italia meeting, 18/02/02 A.Brez – INFN Pisa
Tungsten plate
Vacuum square pockets
Tray reference pinholes
Tray reference pin
The tungsten gluing tool has 16 vacuum pockets to align the tungsten plates
The glue is deposited both on tray and on tunsten plates.The tray is aligned by means of dowels.A 0.2Atm pressure is applied over the tray.
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GLASTGLAST GLASTGLAST Pisa GLAST Italia meeting, 18/02/02 A.Brez – INFN Pisa
Kapton bias circuits gluing tool
1: alignment of the 2 kapton bias circuits on 2 vacuum chucks and glue deposition
2: alignment of tray over the bottom chuck
3: gluing at room temperature of the two circuits together in a reduced vacuum bag (0.2Atm)
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GLASTGLAST GLASTGLAST Pisa GLAST Italia meeting, 18/02/02 A.Brez – INFN Pisa
bridge
handle
Z micrometers
guide
shoulder bridge pins
tray pins
Assembly of the ladders over the tray
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GLASTGLAST GLASTGLAST Pisa GLAST Italia meeting, 18/02/02 A.Brez – INFN Pisa
Transfer bridge
Assembly of the ladders on the trays
Ladder assembly tool
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GLASTGLAST GLASTGLAST Pisa GLAST Italia meeting, 18/02/02 A.Brez – INFN Pisa
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GLASTGLAST GLASTGLAST Pisa GLAST Italia meeting, 18/02/02 A.Brez – INFN Pisa
wafers alignment errors
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10
20
30
40
50
60
70
mm
Problems: the ladder assembly jig is not safe for this purpose :the ladder rubs the reference walls when it is lift on.The friction can cause the lost of the vacuum fixation of the ladder which can move without controlA new alignment tool is under project
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GLASTGLAST GLASTGLAST Pisa GLAST Italia meeting, 18/02/02 A.Brez – INFN Pisa
0
89.5
179
268.
5
358
ladder 0
ladder 1
ladder 2
ladder 30
0.10.2
0.30.4
0.5
0.6
0.7
mm
mm
tray #1 superGLAST tray thickness0=nominal thickness (31.034mm)
min=+0.44mmmax=+0.70mm
ladder 0
ladder 1
ladder 2
ladder 3
0
89.5
179
268.
5
358
ladder 0
ladder 1
ladder 2
ladder 3-0.05
0
0.05
0.1
0.15
0.2
mm
mm
tray #4 superGLAST tray thickness0=nominal thickness (31.034mm)
min=-0.02mmmax=+0.20mm
ladder 0
ladder 1
ladder 2
ladder 3
Need to have a better control of the parallelism and of the distance of the two silicon layers
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GLASTGLAST GLASTGLAST Pisa GLAST Italia meeting, 18/02/02 A.Brez – INFN Pisa
An assembly tests has been performed at SLAC during PDR using BTEM assembly concept:Each tray has 2mm precision holes on the 4 corners4 corner posts refer one tray respect to the subsequent oneThe posts define the height and the horizontal position of the trays in the spaceThe side wall are added at the end
Corner posts
2mm
h
Tower assembly procedure: US proposal
Alignment errors pileup even with very demanding requirements on the tolerances, the final alignment is poor
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GLASTGLAST GLASTGLAST Pisa GLAST Italia meeting, 18/02/02 A.Brez – INFN Pisa
z
yx
Pre-assembly of the tower in open condition:The trays are hold and positioned by the 2 reference walls.Two sides are completely freeOn the other two sides the slots of the reference walls allow full cabling
Italy assembly concept:Refer the trays to the side walls of the tower.The side walls are Carbon fibre plates, 1.5mm thick. On the side walls there are holes for the screws and precision holes in correspondence with the reference holes on the tray closeouts.Each tray is referred to the side walls reference system independently of the other trays
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GLASTGLAST GLASTGLAST Pisa GLAST Italia meeting, 18/02/02 A.Brez – INFN Pisa
Stop pin
Reference pin
Screwing holes
Stop pins: 4 pins on the corners avoid accidental contacts between the trays
Reference pins: 3 pins define the height and the position of the tray in space
The tray is screwed against one of the reference walls
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GLASTGLAST GLASTGLAST Pisa GLAST Italia meeting, 18/02/02 A.Brez – INFN Pisa
When the tower is fully assembled, cabled and tested, two reference walls put in place the first two side walls. The trays are referred and fixed to the carbon fibre side wallsThe reference walls with the slots are removedThe last 2 side walls are put in place with other 2 reference walls
Reference walls of the X side walls
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GLASTGLAST GLASTGLAST Pisa GLAST Italia meeting, 18/02/02 A.Brez – INFN Pisa
# Tray type close-out producer19 top Carbon-Carbon PCI18 glast Carbon-Carbon PCI17 glast Carbon-Carbon PCI16 glast Carbon-Carbon PCI15 glast Carbon-Carbon PCI14 Al mass model Al SLAC13 Al mass model Al SLAC12 Al mass model Al SLAC11 Al mass model Al SLAC10 Al mass model Al SLAC
9 Al mass model Al SLAC8 Al mass model Al SLAC7 Al mass model Al SLAC6 superGLAST Carbon-Carbon Plyform5 superGLAST Carbon-Carbon Plyform4 superGLAST Carbon-Fibre Plyform3 superGLAST Carbon-Fibre Plyform2 Al mass model Al SLAC1 bottom Carbon-Carbon PCI
side walls: Carbon-Fibre
Tower assembly and vibrational test: SLAC 20-28 february
The components of the pre-engineering tower have been produced:Top, bottom and 4 GLAST trays made by PCI following the Hytec assembly procedure9 Aluminium mass models (trays with Al closeouts, honeycomb and face-sheets, with similar mechanical properties) produced by SLAC4 superGLAST trays produced by Plyform following the INFN assembly procedure
This week a full assembly exercise of the tower will be carried out at SLACThe week after the tower will be shaked
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GLASTGLAST GLASTGLAST Pisa GLAST Italia meeting, 18/02/02 A.Brez – INFN Pisa
Conclusions
A prototype of the engineering tower is ready to be mounted
The engineering of two ladder production lines (G&A,Mipot) and of one tray assembly line (Plyform) has been completed successfully
Open questions:QA of the tray assembly line not yet developed.Engineering Model : CMM measurements in INFN Dynamical tests: in Centrotecnica (samples) + qualification (all trays)
Need to develop a light system to check dinamically the workmanship at different levels (search of main resonance modes)