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					            LCLS Undulator Bellows Module
                        Internal Design Review



                             Soon-Hong Lee




Jan. 6, 2006                        1
Chamber & Bellows IDR
                         Contents
       Layout
       General Requirements
       Specifications
       Conceptual Designs
       Materials for Bellows Module
       FE Stress Analysis
       Mechanical Failure Test
       Conclusions




Jan. 6, 2006                   2
Chamber & Bellows IDR
                               Layout
                        Short Break Diagnostic Section




Jan. 6, 2006                         3
Chamber & Bellows IDR
                        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




                                  • 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
From www.flexhose.com             • Total angular rotation  0.5

Jan. 6, 2006                            4
Chamber & Bellows IDR
                        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




Jan. 6, 2006                                 5
Chamber & Bellows IDR
                              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 fingers
                               0.2 ~ 0.3 mils Rhodium plating on the Stub tube/Spring fingers




Jan. 6, 2006                                    6
Chamber & Bellows IDR
                            Bellows Module
 EVAC flanges with                           Removable tie rods
  chain clamps for                             for restraints to
space limitation and                          prevent damages
 easy maintenance




  Welded Bellows                               RF-connections
  (200-125-3-EE)
 Axial travel: 16~60 mm
 lateral offset:  4.3 mm
    angular offset: 50



Jan. 6, 2006                      7
Chamber & Bellows IDR
                 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

 Jan. 6, 2006                8
 Chamber & Bellows IDR
         Materials for RF Fingers and Stub




             Flange     Stub Tube Need Heat Treatment Fingers
                                     after forming
                                                                Fingers
Jan. 6, 2006                                9
Chamber & Bellows IDR
                  RF Finger Stress Analysis




                        3 mm at tip




Jan. 6, 2006                     10
Chamber & Bellows IDR
                  RF Finger Stress Analysis




                        324.8 MPa at root >
                        Fatigue strength of
                        BeCu (276MPa)




Jan. 6, 2006                             11
Chamber & Bellows IDR
                         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      Spring finger              RF-finger tip


Jan. 6, 2006                                12
Chamber & Bellows IDR
                                        FEA Case Study
        + 2mm
                                                  • Use Pro/Mechanica - Contact Analysis
                                                    - Surfaces of fingers & stub are contacted
                         + 5 mm                     - Applied ±2 mm (Y) for lateral offset, ± 5 mm (Z) for axial travel
                                   - 2mm          • Criteria
                                                    - Maximum Displacement < 8.0 mm
                                                    - Maximum Stress < 276 MPa
                                                     (based on fatigue strength of BeCu Alloy 174)
                         RF Fingers              Spring Finger
Case    Contact                                                        Thickness    Maximum       Maximum       Z-travel
                   No. of   Root         Tip     No. of       Finger
                                                                                   Displacement    Stress      (± 5 mm )
                  Fingers   angle       angle   Fingers       angle
  1                 18       18º         8º       8                                  3.85 mm      225 MPa     Contracted
  2      Point      9        36º         16º      8                                  3.82 mm      397 MPa     Contracted
        Contact                                                45º
 3-1                16       20º         8º       8                                  3.79 mm      226 MPa     Contracted
                                                                       0.15mm
 3-2                16       20º         8º       8                                  2.87 mm      144 MPa      Extended
  4                 18       18º         8º       8                                  3.13 mm      281 MPa     Contracted
  5                 18       18º         10º      9            40º                   3.04 mm      304 MPa     Contracted
        Surface
  6     Contact     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


Jan. 6, 2006                                                    13
Chamber & Bellows IDR
                        Case 1




Jan. 6, 2006              14
Chamber & Bellows IDR
                        Case 3-1




Jan. 6, 2006               15
Chamber & Bellows IDR
                        Case 3-2




Jan. 6, 2006               16
Chamber & Bellows IDR
                        Case 8




Jan. 6, 2006              17
Chamber & Bellows IDR
                        Case 9




Jan. 6, 2006              18
Chamber & Bellows IDR
                        RF Fingers




                                     0.15 mm thick
                                     53.5 mm long
                                       16 fingers




Jan. 6, 2006                19
Chamber & Bellows IDR
                        Spring Fingers




                                         0.15 mm thick
                                         29.5 mm long
                                            8 fingers




Jan. 6, 2006                  20
Chamber & Bellows IDR
                 Bellows Module Assembly




Jan. 6, 2006                21
Chamber & Bellows IDR
                                   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                   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-           BeCu 174-HT       Thickness: 0.15 mm                 1lb/ free   Brush Wellman, Inc.
fingers /                          Width: 35 mm                       sample      (1 lb free, $500 min. lot charge)
                 BeCu 25-1/2HT
 Spring-                           Length: 55 mm
 fingers         GlidCop A-15                                                     Spot Welding Consultant, Inc.
                                                                      $460.00 /   J. L. Anthony & Company
                                                                      min. 5 lb
Bellows          Stainless Steel   P/N: 200-125-3-EE                  $ 271.00    Standard Bellows Company
                       347         Lateral offset: ±0.17˝ (4.3 mm)    /Ea
                                   Angular offset: ± 50°
                                   @ installed length of 1.59˝

Jan. 6, 2006                                                     22
Chamber & Bellows IDR
                        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.




Jan. 6, 2006                   23
Chamber & Bellows IDR
              RF Fingers and Stub Plating
                    Bellows Testing



                        Jim Morgan




Jan. 6, 2006                 24
Chamber & Bellows IDR
                      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


Jan. 6, 2006                              25
Chamber & Bellows IDR
                                 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                              26
Chamber & Bellows IDR
     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



Jan. 6, 2006                   27
Chamber & Bellows IDR
                  Section Thru Test Fixture
Set-up for dynamic axial Testing




Jan. 6, 2006                       28
Chamber & Bellows IDR
               Enlarged View – Test Fixture
Enlarged view




Jan. 6, 2006                29
Chamber & Bellows IDR
               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     3/6/2006
               UN43_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     5/24/2006
               UN43_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                                              30
Chamber & Bellows IDR
                   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




Jan. 6, 2006                                31
Chamber & Bellows IDR

				
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