mechanical design and tests of the new x-band flange

1[11-Sep-2013] «BE-RF-PM»

Mechanical design and tests of the new X-band flange

EDMS №1312687

A. Samochkine

1

2[11-Sep-2013] [RF Development Meeting] «BE-RF-PM» 2

Alexandre.Samochkine @ cern.ch

Contents

1. Aim and Testing

2. Requirements

3. Features in 3D model

4. Drawings

5. Tolerances

6. Configurations

7. Pre-series production

8. Mechanical test results and comparison with simulations

9. Mechanical test results

10.Proposal on configuration

Ref. :CLIAVACU0189ST0436757

Knife “Squared shape" Gasket 1 mm thick

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Alexandre.Samochkine @ cern.ch

International Universal X-Band Flange (IUWR90)

Mechanical design aim

Develop WR90 common RF vacuum flange design in collaboration with different laboratories.

PM Testing

• Tests on gaskets• Assembly and disassembly;• Leak tightness tests;• Mechanical measurements;• Baking.

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Set of required flange features

1. Rectangular flange with 8 bolts 2. Precision outside dimensions for easy assembly verification 3. Grooves from gasket to outside of flange for leak test 4. Corners of gasket seat to be made circular for ease of gasket removal5. No guide pins, study external alignment jig 6. Internal radius on corners of flange gasket knife to be made a big as reasonably

possible 7. Simple rectangular copper gasket 1mm thick, completely annealed 8. Threaded hole on flange side for mounting 9. Minimize length of the RF part of flange (in case if used without copper plating). 10. Consider brazed side with round pockets near waveguide edges (like in KEK flange or

Haimson's WR62).

(Recommendation of committee. KEK collaboration meeting - May 2012)

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Features in 3D model

1

3

2, 5

4 6

7

8

9

10

1. Rectangular flange with 8 bolts 2. Precision outside dimensions for easy assembly verification 3. Grooves from gasket to outside of flange for leak test 4. Corners of gasket seat to be made circular for ease of gasket removal5. No guide pins, study external alignment jig 6. Internal radius on corners of flange gasket knife to be made a big as reasonably possible 7. Simple rectangular copper gasket 1mm thick, completely annealed 8. Threaded hole on flange side for mounting 9. Minimize length of the RF part of flange (in case if used without copper plating). 10. Consider brazed side with round pockets near waveguide edges (like in KEK flange or Haimson's WR62).

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Flange drawing (CLIAVACU0189)

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Design iterations

2 main knife parameters:

1. Flat knife edge width• 0.5 mm• 0.75 mm• 1 mm

2. Gasket compression • 0.2 mm• 0.3 mm• 0.4 mm• 0.5 mm

12 versions

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Flange drawing (CLIAVACU0189)

Reference External surfaces

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Copper coating

Machining dimensions before copper coatingRequirement 9

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Gasket drawings (CLIAVACU0190 & …191)

CLIAVACU0190, clearance fit CLIAVACU0191, Interference fit

20

-0.02-0.04

+0.03+0.01

32.7

-0.02-0.04

+0.03+0.01

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Procurement

• Pre-series - procurement of 48 flanges

(12 configurations x 2 sets of 2 flanges each); - 50 gaskets with a clearance fit and 50 with interference fit

• First series of 150 sets of the most successful configuration chosen through the pre-series phase.

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Testing

Test on gasket compression (EDMS 1289259)

Dimensional control of gaskets after use (EDMS 1303470)

Thermal test of copper coating quality• 920 °C • 250 °C (according to ASTM B571-97)

Test on multiple usage of flange

Leak test (EDMS 1290515)

High power test at SLAC

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Test on gasket compression (EDMS N1289259) [part1]

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Conclusions after gasket compression test

Two gaskets were inspected after use in assemblies of IUWR90 flanges.

The expansion of gasket into waveguide zone observed in case of flanges “4 – 4 1EM” is about 0.15 mm all around.

The expansion of gasket into waveguide zone observed in case of flanges “9 – 9 1EM” is about 0.1 mm all around.

The vacuum sealing is equally successful in both cases.

The use of flanges “9 – 9 1EM” is preferable because of smaller expansion into RF zone.

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Gasket deformations after use (EDMS 1303470) [part2]

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• 10 different flange pairs of different designs (variation of “pressure width” “a” and “pressure depth” “b)• Every gasket has same initial dimensions• Assemblies are screwed together until stainless steel parts are in contact• After 48 hours, assemblies are dismounted and the deformed gaskets openings were measured. The aim is to assess how deep the gasket penetrates into RF volume after mounting as a function of “a” and “b”

X₀ as reference opening

Flange

X₁ as initial verification

New gasket Tested gasket

X as final opening

Openings measured in two ways:

Ceramic gauge block set Optical Stereo microscope

-> accuracy depends on user: ~0.02 mm

suitable and fast way of assessing the opening

new gaskets

tested gaskets and flanges

Measurements by M. Rissanen

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The expansion of gasket into waveguide into the RF volume for design 12 (highest “a” and smallest “b“) is biggest 0.295 mm

The expansion of gasket into waveguide into the RF volume for design 7 (smallest “a” and biggest “b“) is smallest 0.079 mm

For further reduction of the protrusion length “a” should be further decreased below 0.5 and “b” should be further increased above 0.4. The limit is represented only by the leak tightness, which is yet to be assessed.

a \ b 0.25 0.30 0.35 0.40

0.50 0.227 X 0.124 0.079

0.75 0.280 0.224 0.114 X

1.00 0.295 0.210 0.214 0.143

Conclusions after dimensional control of used gaskets

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Thermal test of copper coating quality

920 °C 250 °CThe copper plating on three flanges CLICAVACU0027 where tested according to the ATMS procedure “B571-97 TEST D’ADHESION INOX CUIVRE” chapter 9, Heat-Quench Test.

The procedure or testing the adhesion of copper coating to stainless steel:- heat up the copper coated stainless steel part to 250 °C and keep for

10 minutes (for being sure the whole part has uniform temperature) - rapid cooling in demineralised water at room temperature (20 °C).

If the copper plating doesn’t crack or start to peel of the coating is good.

Equipment:The furnace used was a VENTICELL 222 with air filter class S DIN 24 184 and a forced ventilation.

Brazing cycle was used to see if the copper coated flange sustains the heating (baking).

The good copper adhesion is proved by both tests.

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Test on multiple usage of fully copper coated flange

The goal for these tests is to learn how the copper coating of the knife zone of the RF vacuum flange is affected during several assemblies with gaskets. The flange used was CLIAVACU0189 version 1, 6 and 12 The gaskets used were CLIAVACU0191 and CLIAVACU0190.First all combinations where assembled and studied. The combination with the biggest deformation on the gasket was chosen for the tests to be repeated. The greater the deformation of the gasket is, the bigger the impact on the knife was expected. After repeated assemblies more and more scratches appear.

Small additional scratches appear after each assembly. The deformation of the gasket is also the biggest in shown zone.

Assembled 4 times Assembled 9 timesInspection by F. Smeds

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Conclusions after several assemblies

The whole flange copper coating is more cost effective.

The micro scratches observed on the knife surface after ten assemblies are negligible. That must be confirmed by deeper analysis (measurements). Most probably the annealed gasket will fill the cracks and scratches created during previous assembly.

Proposal for next steps• Vacuum leak tightness tests with plated flanges and

repeated assemblies.• SEM pictures for deeper knowledge on the coating

and the scratches.

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Simulation of the gasket compression

The aim: Evaluate the deformations of the gasket compressed

between two flanges Evaluate the torque required to tighten the screws

12 gasket versions with varying flange knife dimensions

FLANGE

GASKET

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Simulation of the gasket compression

Version 3D model (µm) Exp. measurements (µm)1 188 114 (-39 %)6 300 210 (-30 %)7 86 79 (-8 %)

12 373 295 (-21 %)

Gasket deformation under compression

Study by L. Kortelainen

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Sub-assemblies for high power test at SLAC

CLIATLRF0128 CLIATLRF0129

Inlet inspection of 8 units of IUX Test setup assembly. (EDMS 1289257)

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Sub-assemblies for high power test

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Leak test (EDMS # 1290515)

Max. measured leak rate: Version 12/12 1EM & 1/1 1EM: 4.0 x 10⁻¹⁰ mbar•l/s Version 4/4 1EM & 9/9 1EM: 7.0 x 10⁻¹⁰ mbar•l/s

Leak detector type: ASM 121 h Reference leak rate: 6.2±15% ×10⁻⁷ mbar•l/s Minimum detectable leak rate: 2×10⁻¹⁰ mbar•l/s Tracer gas: Helium 99%System pressure: 1×10⁻³ mbarTest temperature: 20 C ̊

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Shipping to SLAC for high power test

24-May-2013

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Conclusions

From PM fabrication, inspection and tests:- Fully coated flange is recommended - Version 7 is recommended as it gives the smallest

deformation

Waiting for High Power test results at SLAC to launch the series production

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SPARE SLIDES

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Alignment & fixation

Clamping tool. Schematic view.

Specially sized cantilever clamp with cylindrical grips to be designed. The self-adjustment in both, horizontal and vertical directions, as well as fixation before and during the bolts tightening is provided by pushing against the V-shaped grooves.

for example

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Two configurations

Knife “Improved" & optimizedGasket 2 mm thick

Option 1 Option 2

Knife “Squared shape" Gasket 1 mm thick

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Gasket retention

Minor friction keeps the gasket in place in any

angular position