Design Review Bellows

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Jan. 6, 2006Chamber & Bellows IDR

1

LCLS Undulator Bellows Module

Soon-Hong Lee

Internal Design Review




2

LayoutGeneral Requirements

Specifications

Conceptual Designs

Materials for Bellows ModuleFE Stress Analysis

Mechanical Failure Test

Conclusions

Contents




3

LayoutShort Break Diagnostic Section




4

From www.flexhose.com

• 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 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

• Adjacent two undulators are tilted and/or in parallel• Quad center manual adjustment range = 2.0 mm

• Total lateral offset

2.0 mm

General RequirementsBellows motion requirements




5

General Requirements

Mechanical Concept of Bellows ModuleConsider axial travels/constraints for easy installation and maintenanceConsider lateral offset with flexible contact fingers and static stubConsider maintenance cycle and material fatigue lifeConsider mechanical restraints to prevent damages for bellows and fingers

RF Connections

Provide a sliding surface with good lubricity and good electric conductivityRF fingers, spring fingers, and stub mechanismRF seal ring or spring gasket across flange joints

0.4 ~ 0.5 mils silver plating on the shield fingers0.2 ~ 0.3 mils rhodium plating on the stub




6

Specifications

Flexibility 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)

Life At least 2,000 cycles

Vacuum 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 Bake at 200 C and Operation Heating

Contact Resistance Heating

Structural Loads Fatigue stress due to flexible strokes across the module

Gravity, vacuum force, and contact force

Plating Requirements 0.4 ~ 0.5 mils Silver plating on the RF-shielding fingers0.2 ~ 0.3 mils Rhodium plating on the Stub tube/Spring fingers




7

Bellows Module

Removable tie rodsfor restraints to

prevent damages

Welded Bellows(200-125-3-EE)

Axial travel: 16~60 mmlateral offset: 4.3 mm

angular offset: 50

EVAC flanges withchain clamps for

space limitation andeasy maintenance

RF-connections




8

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




9

Materials for RF Fingers and Stub

FingersStub Tube FingersFlange Need Heat Treatment

after forming




10

RF Finger Stress Analysis

3 mm at tip




11

RF Finger Stress Analysis

324.8 MPa at root >Fatigue strength ofBeCu (276MPa)




12

Design Parameters

RF-finger root

RF-finger tip

• 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

Spring fingerStub




13

FEA Case Study

Case Contact

RF Fingers Spring Finger

Thickness Maximum

Displacement

Maximum

Stress

Z-travel

(± 5 mm )No. ofFingers Rootangle Tipangle No. ofFingers Fingerangle

1

Point

Contact

18 18º 8º 8

45º

0.15mm

3.85 mm 225 MPa Contracted

2 9 36º 16º 8 3.82 mm 397 MPa Contracted

3-1 16 20º 8º 8 3.79 mm 226 MPa Contracted

3-2 16 20º 8º 8 2.87 mm 144 MPa Extended

4

Surface

Contact

18 18º 8º 8 3.13 mm 281 MPa Contracted

5 18 18º 10º 9 40º 3.04 mm 304 MPa Contracted

6 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

• 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)

- 2mm

+ 2mm

+ 5 mm




14

Case 1




15

Case 3-1




16

Case 3-2




17

Case 8




18

Case 9




19

RF Fingers

0.15 mm thick53.5 mm long

16 fingers




20

Spring Fingers

0.15 mm thick29.5 mm long

8 fingers




21

Bellows Module Assembly




22

Mechanical Failure TestObject 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 Vendors

Stub OFE Cu Tube ½˝ O.D. x 0.0625˝ THK x 1.5˝ LG Copper and Brass Sales

OFE Cu Rod 5/8˝ O.D. x 1.5˝ LG

Fixtures OFE Cu Plate 5/16˝ (or 1/4˝) x 12˝ x 72˝

RF-fingers /Spring-

fingers

BeCu 174-HT Thickness: 0.15 mmWidth: 35 mmLength: 55 mm

1lb/ freesample

Brush Wellman, Inc.(1 lb free, $500 min. lot charge)

BeCu 25-1/2HT

GlidCop A-15 Spot Welding Consultant, Inc.$460.00 /min. 5 lb

J. L. Anthony & Company

Bellows Stainless Steel347

P/N: 200-125-3-EELateral offset: ±0.17˝ (4.3 mm)

Angular offset:± 50° @ installed length of 1.59˝

$ 271.00/Ea

Standard Bellows Company






24

RF Fingers and Stub Plating

Bellows Testing

Jim Morgan






26

Approach

1. Plate RF Fingers and Stub with Rd and Ag according tospecifications developed for the bellows for the PEP- IIHigh Energy Ring*

2. Test fingers as assembled inside the bellows to insureacceptable performance at operating conditions for 2000cycles

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




27

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 jointinclude:

Dicronite – impregnated Tungsten Disulfide

Nanolube – nested nanoshpere structure Tungsten

Disulfide




28

Section Thru Test Fixture

Set-up for dynamic axial Testing




29

Enlarged View – Test Fixture

Enlarged view




30

Bellows Prototype Schedule

Activity ID Activity description Early start Early finish

UN43_00242 Study of Lubrication Coating 05/02/05A 11/30/2005

UN43_00243 Proto Mech. Anal. 06/15/05A 11/30/2005

UN43_00241 Proto Prelimin Design 07/22/05A 11/30/2005

UN43_00245 Test Tooling Design 11/01/05* 11/30/2005

UN43_00244 Evaluation of Lubrication Coating 11/22/05* 1/12/2006

UN43_00246 Proto Review 1/13/2006 1/30/2006

UN43_00247 Proto Final Design 1/31/2006 2/20/2006

UN43_00248 Write Bellow Fab Spec 2/14/2006 3/1/2006

UN43_00201 Test Equipment Fab & Assy 2/21/2006 4/3/2006

UN43_00070 Bid Package-Ag Plated RF Finger Prtp Bel Mod 3/2/2006 3/6/2006UN43_00080 Bid Package-Rh Plated Stub Prtp Bel Mod 3/2/2006 3/6/2006

UN43_00090 Bid Package-Tubes Prtp Bel Mod 3/2/2006 3/6/2006

UN43_00100 Bid Package- Prtp Bellows Module 3/2/2006 3/6/2006

UN43_00120 Bid Process Prtp Bel Mod 3/7/2006 4/10/2006

UN43_00130 Procure Ag Plated RF Finger Prtp Bel Mod 4/11/2006 4/12/2006

UN43_00140 Procure Rh Plated Stub Prtp Bel Mod 4/11/2006 4/12/2006

UN43_00150 Procure Tubes Prtp Bel Mod 4/11/2006 4/12/2006

UN43_00160 Procure Bellows Prtp Bel Mod 4/11/2006 4/12/2006

UN43_00180 Prototype Bel Mod Award Complete 4/12/2006

UN43_00190 RCV: Bellows Prtp Bel Mod 4/13/2006 5/24/2006UN43_00200 Quality Assurance Prtp Bel Mod 5/25/2006 6/1/2006

UN43_00220 Measurement and Test Prtp Bel Mod 6/2/2006 6/15/2006

UN43_00230 Review and Report Prtp Bel Mod 6/16/2006 6/22/2006

UN43_00240 Prototype Bel Mod Testing Complete 6/22/2006



Jan. 6, 2006 31

Bellows Prototype Costs

•Material costs from current loaded schedule

•Bellows $ 1,500

•Test Equipment $ 4,000

•Evaluation of plating $ 3,000

•Rh plate stub $ 900• Ag plate fingers $ 3,000

•Fabrication of small parts $ 600

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