LCLS Undulator Bellows Module
Internal Design Review
Soon-Hong Lee
Jan. 6, 2006
Chamber & Bellows IDR
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Contents
Layout
General Requirements
Specifications
Conceptual Designs
Materials for Bellows Module
FE Stress Analysis
Mechanical Failure Test
Conclusions
Jan. 6, 2006
Chamber & Bellows IDR
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Layout
Short Break Diagnostic Section
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General Requirements
Bellows motion requirements
• Baking temperature at ~200 C
• Fabrication tolerance of chamber, BPM, Quad.
• Longitudinal cradle motion constraint =  3.0 mm
• Total axial travel   5.0 mm
• Adjacent two undulators are tilted and/or in parallel
• Quad center manual adjustment range =  2.0 mm
• Total lateral offset   2.0 mm
From www.flexhose.com
Jan. 6, 2006
Chamber & Bellows IDR
• Adjacent two undulators are tilted symmetrically
• Angular stroke for bellows module = 2  tan–1 (height
change/length between bellows module)
• Height change = 2 mm   (~2.5) + 2 mm   (~2.5) =
10 mm 2 x tan–1 (10/3800) = 0.3
• Undulator segment pitch tolerance (rms) = 14 rad
• Total angular rotation  0.5
4
General Requirements
Mechanical Concept of Bellows Module
Consider axial travels/constraints for easy installation and maintenance
Consider lateral offset with flexible contact fingers and static stub
Consider maintenance cycle and material fatigue life
Consider mechanical restraints to prevent damages for bellows and fingers
RF Connections
Provide a sliding surface with good lubricity and good electric conductivity
RF fingers, spring fingers, and stub mechanism
RF seal ring or spring gasket across flange joints
0.4 ~ 0.5 mils silver plating on the shield fingers
0.2 ~ 0.3 mils rhodium plating on the stub
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Specifications
Flexibility
Life
Vacuum
Allow  0.5 of Angular Stroke (Pitch and Yaw)
Allow  2.0 mm of Lateral Stroke (X & Y axes)
Allow  5.0 mm of Axial Stroke (Z axis)
At least 2,000 cycles
1 x 10 –7 Torr
Low Beam Impedance
Electric continuity by RF fingers and RF seal ring or spring gasket
across flange joint
Space Constraints
Minimize beam directional overall length of module (Z-axis)
Axial constraint mechanism for easy installation and maintenance
Thermal Loads
Structural Loads
Plating Requirements
Jan. 6, 2006
Chamber & Bellows IDR
Bake at 200 C and Operation Heating
Contact Resistance Heating
Fatigue stress due to flexible strokes across the module
Gravity, vacuum force, and contact force
0.4 ~ 0.5 mils Silver plating on the RF-shielding fingers
0.2 ~ 0.3 mils Rhodium plating on the Stub tube/Spring fingers
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Bellows Module
EVAC flanges with
chain clamps for
space limitation and
easy maintenance
Removable tie rods
for restraints to
prevent damages
Welded Bellows
(200-125-3-EE)
RF-connections
Axial travel: 16~60 mm
lateral offset:  4.3 mm
angular offset: 50
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Chamber & Bellows IDR
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Bellows Module - Exploded
RF Fingers (BeCu 174)
with Ag-plating
Stub (OFE Cu) &
Spring Fingers (BeCu)
with Rd-plating
RF seal ring or spring gasket
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Materials for RF Fingers and Stub
Flange
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Heat Treatment
Stub Tube Needafter
Fingers
forming
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Fingers
RF Finger Stress Analysis
3 mm at tip
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RF Finger Stress Analysis
324.8 MPa at root >
Fatigue strength of
BeCu (276MPa)
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Chamber & Bellows IDR
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Design Parameters
• To investigate maximum stress at root
• contact types (point contact or surface contact)
• # of RF-fingers
• # of Spring-fingers
• shape of fingers to reduce the overlap damage
• thickness and length of fingers
RF-finger root
Stub
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Chamber & Bellows IDR
Spring finger
RF-finger tip
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FEA Case Study
+ 2mm
+ 5 mm
- 2mm
RF Fingers
• Use Pro/Mechanica - Contact Analysis
- Surfaces of fingers & stub are contacted
- Applied ±2 mm (Y) for lateral offset, ± 5 mm (Z) for axial travel
• Criteria
- Maximum Displacement < 8.0 mm
- Maximum Stress < 276 MPa
(based on fatigue strength of BeCu Alloy 174)
Spring Finger
Maximum
Displacement
Maximum
Stress
Z-travel
(± 5 mm )
3.85 mm
225 MPa
Contracted
3.82 mm
397 MPa
Contracted
3.79 mm
226 MPa
Contracted
8
2.87 mm
144 MPa
Extended
8º
8
3.13 mm
281 MPa
Contracted
18º
10º
9
40º
3.04 mm
304 MPa
Contracted
15
22º
10º
9
40º
0.30 mm
3.38 mm
553 MPa
Contracted
7
9
36º
18º
9
40º
0.15 mm
3.84 mm
423 MPa
Contracted
8, 9
18
0.15 mm
6.10 mm
221 MPa
No Spring
fingers
Case
Contact
No. of
Fingers
Root
angle
Tip
angle
No. of
Fingers
18
18º
8º
8
9
36º
16º
8
3-1
16
20º
8º
8
3-2
16
20º
8º
4
18
18º
18
1
2
Point
Contact
5
6
Surface
Contact
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Chamber & Bellows IDR
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Finger
angle
Thickness
45º
0.15mm
-
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Case 1
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Case 3-1
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Case 3-2
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Case 8
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Case 9
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RF Fingers
0.15 mm thick
53.5 mm long
16 fingers
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Spring Fingers
0.15 mm thick
29.5 mm long
8 fingers
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Chamber & Bellows IDR
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Bellows Module Assembly
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Chamber & Bellows IDR
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Mechanical Failure Test
Object of failure test is to prove the part in the following conditions
1.
2,000 cycle actuation
2.
± 5.0 mm axial travel distance
3.
± 2.0 mm lateral offset movement
4.
 0.5 of angular stroke
5.
Ag- & Rd- plating thickness
Materials
Size
Price
OFE Cu Tube
½˝ O.D. x 0.0625˝ THK x 1.5˝ LG
OFE Cu Rod
5/8˝ O.D. x 1.5˝ LG
Fixtures
OFE Cu Plate
5/16˝ (or 1/4˝) x 12˝ x 72˝
RFfingers /
Springfingers
BeCu 174-HT
Thickness: 0.15 mm
Width: 35 mm
Length: 55 mm
Stub
Bellows
BeCu 25-1/2HT
Copper and Brass Sales
1lb/ free
sample
GlidCop A-15
Stainless Steel
347
Jan. 6, 2006
Chamber & Bellows IDR
Vendors
Brush Wellman, Inc.
(1 lb free, $500 min. lot charge)
Spot Welding Consultant, Inc.
P/N: 200-125-3-EE
Lateral offset: ±0.17˝ (4.3 mm)
Angular offset: ± 50°
@ installed length of 1.59˝
22
$460.00 /
min. 5 lb
J. L. Anthony & Company
$ 271.00
/Ea
Standard Bellows Company
Conclusions
Established design specifications based on physics
requirements, maintenance, and installation etc.
Conceptual design and drawings are completed.
Based on FE analysis (contact analysis) by use of
Pro/Mechanica, max. stress on fingers is expected to
have 226MPa which shows below fatigue strength
(276 MPa) of BeCu Alloy 174.
Lubricity and mechanical failure tests are planned to
investigate the Rd- & Ag-plating thickness and the
performance of RF- & Spring-fingers.
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Chamber & Bellows IDR
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RF Fingers and Stub Plating
Bellows Testing
Jim Morgan
Jan. 6, 2006
Chamber & Bellows IDR
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RF Fingers and Stub
Plating and Test Requirements
Plating Requirements
Maintain electric continuity and provide lubricity across the sliding joint ( RF
fingers and Stub) during operations
Optimize plating performance
•Avoid galling
•Minimize loss of plating
•Avoid loss of plating adhesion (flaking)
Testing Parameters for Bellows Assembly and Sliding Joint
•Test at 10-7 torr
•Allow visual inspection of sliding joint during the test
•2000 cycle test
•±5mm axial travel (static and dynamic)
•±2mm lateral offset (static and dynamic)
•±0.5° angular offset
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Approach
1. Plate RF Fingers and Stub with Rd and Ag according to
specifications developed for the bellows for the PEP- II
High Energy Ring*
2. Test fingers as assembled inside the bellows to insure
acceptable performance at operating conditions for 2000
cycles
3. Change coating thicknesses if required
4. Optimize performance as budget and schedule allow
*Curt Besler, Jeffery Berg “High Current RF Shield for PEP-II Vacuum System Expansion
Joint” LLNL
M.E. Nordby, N. Kurita “Bellows Design for PEP-II High Energy Ring Arc Chambers” SLAC
Jan. 6, 2006
Chamber & Bellows IDR
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Plating Materials and Initial Thickness
RF Fingers – 0.4 to 0.5 mils Ag
Stub – 0.2 to 0.3 mils Rd
Plating thickness can be changed to optimize performance.
Other possible materials for increased lubricity at the joint
include:
Dicronite – impregnated Tungsten Disulfide
Nanolube – nested nanoshpere structure Tungsten
Disulfide
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Chamber & Bellows IDR
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Section Thru Test Fixture
Set-up for dynamic axial Testing
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Enlarged View – Test Fixture
Enlarged view
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Bellows Prototype Schedule
Activity ID
UN43_00242
UN43_00243
UN43_00241
UN43_00245
UN43_00244
UN43_00246
UN43_00247
UN43_00248
UN43_00201
UN43_00070
UN43_00080
UN43_00090
UN43_00100
UN43_00120
UN43_00130
UN43_00140
UN43_00150
UN43_00160
UN43_00180
UN43_00190
UN43_00200
UN43_00220
UN43_00230
UN43_00240
Jan. 6, 2006
Chamber & Bellows IDR
Activity description
Study of Lubrication Coating
Proto Mech. Anal.
Proto Prelimin Design
Test Tooling Design
Evaluation of Lubrication Coating
Proto Review
Proto Final Design
Write Bellow Fab Spec
Test Equipment Fab & Assy
Bid Package-Ag Plated RF Finger Prtp Bel Mod
Bid Package-Rh Plated Stub Prtp Bel Mod
Bid Package-Tubes Prtp Bel Mod
Bid Package- Prtp Bellows Module
Bid Process Prtp Bel Mod
Procure Ag Plated RF Finger Prtp Bel Mod
Procure Rh Plated Stub Prtp Bel Mod
Procure Tubes Prtp Bel Mod
Procure Bellows Prtp Bel Mod
Prototype Bel Mod Award Complete
RCV: Bellows Prtp Bel Mod
Quality Assurance Prtp Bel Mod
Measurement and Test Prtp Bel Mod
Review and Report Prtp Bel Mod
Prototype Bel Mod Testing Complete
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Early start
05/02/05A
06/15/05A
07/22/05A
11/01/05*
11/22/05*
1/13/2006
1/31/2006
2/14/2006
2/21/2006
3/2/2006
3/2/2006
3/2/2006
3/2/2006
3/7/2006
4/11/2006
4/11/2006
4/11/2006
4/11/2006
4/13/2006
5/25/2006
6/2/2006
6/16/2006
Early finish
11/30/2005
11/30/2005
11/30/2005
11/30/2005
1/12/2006
1/30/2006
2/20/2006
3/1/2006
4/3/2006
3/6/2006
3/6/2006
3/6/2006
3/6/2006
4/10/2006
4/12/2006
4/12/2006
4/12/2006
4/12/2006
4/12/2006
5/24/2006
6/1/2006
6/15/2006
6/22/2006
6/22/2006
Bellows Prototype Costs
•Material costs from current loaded schedule
Jan. 6, 2006
Chamber & Bellows IDR
•Bellows
$ 1,500
•Test Equipment
$ 4,000
•Evaluation of plating
$ 3,000
•Rh plate stub
$
•Ag plate fingers
$ 3,000
•Fabrication of small parts
$ 600
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900