1

RF-Structures Mock-Up FEA Assembly Tooling

V. Soldatov, F. Rossi, R. Raatikainen27.6.2011

2

INDEX

1. EBW tooling for PETS

Introduction • General description• Assembly on tooling• Transportation• EBW process

FEA• Loading and Boundary Conditions• Results

Conclusions

2. Brazing tooling for AS

Introduction• General description• Assembly on tooling• Brazing process

FEA

• Loading and Boundary Conditions• Results

Conclusions

3

1. EBW tooling for PETS

Introduction • General description• Assembly on tooling• Transportation• EBW process

FEA• Loading and Boundary Conditions• Results

Conclusions

2. Brazing tooling for AS

Introduction• General description• Assembly on tooling• Brazing process

FEA

• Loading and Boundary Conditions• Results

Conclusions

4

General description

Closure assy 1

Mock-up (damped) assembly

Minitank (short) assembly

Middle connection assy

614.35 mm

271.5 mm

202 mm

Closure assembly 2

FrictionalcontactFrictional

contactEBW EBW

EBW EBW

Minitank assembly

NO

5

Assembly on tooling

Bearing

Upper eye-bolt

Upper bolt

Upper cap cover

Lateral eye-bolt

Holding-device

Lower cap cover

Lower bolt

Lateral eye-bolt

Nut

Threaded rod

Nut• Bearing: allow EBW tooling rotation around its axis, once it is

positioned on the EBW machine.

• Upper cap cover: apply clamping force to PETS unit, once the nut is screwed on the threaded rod.

• Upper bolt: fix upper cap cover and closure assy 2.

• Eye-bolts: for lifting and handling.

• Threaded rod (M16): connection between the upper and the lower cap cover.

• Lower cap cover: sustain PETS unit during the assembly on the tooling.

• Lower bolt: fix lower cap cover and closure assy 1.

• Nut (M16): after it is screwed using a torque spanner, a compressive axial load is applied to PETS units (while the rod has tensile stresses).

• Holding device: fix axial and angular position between minitanks and adapter disks.

6

Assembly on tooling

1. The second mock-up (damped) assembly is

inserted into the middle connection assy

2. Minitank assembly is positioned

3. Closure assy 1 is positioned

4. Threaded rod is inserted and the

upper cap cover is positioned

7

Assembly on tooling

6. Clamping force is applied using a torque spanner5. The holding device is fixed

1st FEM analysis: calculate gap variation in function of the applied load

7. Tack welding

8

Transportation

8. Rotation and transport to the EBW machine.

9. The holding device is removed.

FrictionalcontactFrictional

contact

EBW EBW

EBW EBW

2nd FEM analysis: calculate the clamping force necessary to maintain the contact in the designed area (friction forces between adapter disks and mock-up bars are greater

than mock-up bars weight)

9

Clamping force vs. Tightening torque

Ma [Nmm] = Fv ·(0.159·P + 0.578·d₂·µg + 0.5·dKm·µk) = ~ 3·Fv [N]

CLAMPING FORCE

(Fv)

TIGHTENING TORQUE

(Ma)

M16

• P = thread pitch (2 mm)• d2 = thread diameter (16 mm)• µg = friction coefficient of the thread (0.15)

• dKm = average diameter of the bolt head (22.16 mm)• µk = friction coefficient of the bolt head (0.15)

dkm

10

EBW process

Wel

ding

BearingChuckdriven by the

welding machine

FixedV-support

Ground

FEA

Aim

1. Calculate the axial force necessary to hold the assembly on the tooling during the EBW process2. Calculate the deformation involved in the process

Hypothesis

The problem is considered as a static structural and no dynamical effects were taken into account (e.g. rotational speed 0.004 rad/s)

Model and initial clamping force range for further studies

FE-model including:

-All copper parts (Cu-OFE) of PETS-St.Steel PETS flanges, minitank and tooling

The initial gap of 50 µm is reduced to zero. High deformations of minitanks occur.

Friction forces between adapter disks and mock-up bars are lower than mock-up bars weight (the contact is not in the designed area)

Maximum 50 kN

Minimum 0.3 kN

Clamping force

Fixed Gravity

Gravity

1st position 2nd position

Fixed(Motor chuck)

Loading & Boundary Conditions

Bearing condition-The selected ball bearing allows 10 (0.17°) of rotation-Rotation due to gravity is allowed-Translation d.o.f. is fixed

Results – Axial force of 1 kN

Δgap max 1 µm

Δdeflection 10.5 µm

Results – Axial force of 2.5 kN

Δgap max 2 µm

Δdeflection 10.8 µm

Max. Stress 3 MPa

Conclusions

On the basis of FEA performed, the selected clamping force is 2.5 kN, which corresponds to a tightening torque of 7.5 Nm

According to the results, the reduction of initial flanges gap (50 µm) due to the applied load is negligible.

The results show that larger clamping forces do not have significant influence on the transversal deflection of PETS. Anyway, this elastic deflection will be completely recovered once the structure is supported on the designed supports for TM0.

The highest stresses occur around the contact area close to the edge inside the adapter disk. For a clamping force of 2.5 kN the maximum value is less than 3 MPa (σY = 69 MPa)

16

1. EBW tooling for PETS

Introduction • General description• Assembly on tooling• Transportation• EBW process

FEA• Loading and Boundary Conditions• Results

Conclusions

2. Brazing tooling for AS

Introduction• General description• Brazing process• Assembly on tooling

FEA• Loading and Boundary Conditions• Results

Conclusions

17

General description

Cooling circuit

Vacuum flange

RF flange

ManifoldInterconnection

flange

RF waveguide

Accelerating structure

Super-accelerating structure

Target sphere

2031

484

334

18

Brazing process BRAZING

(Au/Cu 25/75, 1040 °C)1. WFM WG cover + WFM WG body (x32=4x8)2. Waveguide damping interface half 1 + half 2 (x32=4x8)3. Stack type 1 (x6)4. Stack type 2 (x1)5. Stack type 3 (x1)6. Manifold cover (tank int.) + vacuum tube P1 (x8)7. Manifold small cover 3 + small cover 3 insert (x32=4x8)

TIG WELDING1. Manifold cover 2 assembly (x8)

MACHINING1. WFM WG brazed (x24=3x8)2. WG damping interface (x16=2x8)

BRAZING(Au/Cu 25/75, 1040 °C)

1. Manifold (hor) assembly (x8=1x8)2. Hor. manifold (mirrored) assembly (x8=1x8)3. Vert. manifold assembly (x16=8x2)

BRAZING(Au/Cu 35/65, 1020 °C)

1. Structure type 1 (x6)2. Structure type 2 (x1)3. Structure type 3 (x1)

BRAZING(Au/Cu 50/50, 980 °C)

1. Brazed stack 1 + AS cooling fitting adapters2. Brazed stack 2 + AS cooling fitting adapters

19

Brazing process

900 °C

1020 °C

Temperature history

20

Assembly on tooling

Rod

Nut

Lower plate

Lateral support

Lateral spring

Lateral plate

Upper support

Upper spring

Wedges

• Lower plate (graphite): support the assembly during alignment operations and brazing cycle.

• Wedges (ceramic): allow small adjustment of manifolds in the vertical direction.

• Lateral springs (graphite): apply an horizontal force to the manifolds through the lateral plates and allow thermal expansion of the assembly during the brazing cycle (k=20 N/mm).

• Lateral supports (stainless steel): support the springs.

• Upper spring (graphite): apply a vertical force on the manifolds through the upper support and allow thermal expansion of the assembly during the brazing cycle.

• Rod (stainless steel): connect upper support and lower plate.

21

Assembly on tooling

1. Graphite plate 2. Disks stack 3. Wedges 4. Manifolds

5. Lateral supports, plates and springs

6. Upper support 7. Rod 8. Upper spring and nut

Tooling for the 1st brazing step

FEA

A static thermal and structural analysis with a temperature variation from 20 °Cto 1020 °C was carried out for the accelerating structure

The thermal expansion is constrained only by the springs, which are situated on the opposite sides of the fixed lateral support

All the connections were considered ideally frictionless to reduce the computational time

Fixed surfaces connected to the lateral support (without springs)

Free surfaces constrained by the springs

Supported on the ground

For the springs a constant stiffness of 20

N/mm was used

Results – thermal expansion

xyz

Max. in x-direction 4.6 mm Max. in y-direction 7.2 mm

Max. in z-direction 5.3 mm

Results – stresses

Max. 0.1 MPa

Stress due to thermal expansion

On the basis of the FEA the displacements and the stresses due to thermal expansion have been calculated

The transversal displacement of the manifolds is approximately 5 mm The axial displacement of the whole structure is approximately 5 mm During the brazing process the calculated stresses are below the copper yield

strength at 1020 °C (σY = 7.5 MPa)

Future work

- Transient thermal analysis to model the temperature history- Thermal and structural simulations for the brazing of 4 AS - Structural analysis for the AS intermediate EBW tooling

Conclusion