RFStructures MockUp FEA Assembly Tooling V Soldatov F

RF-Structures Mock-Up FEA Assembly Tooling V. Soldatov, F. Rossi, R. Raatikainen 27. 6. 2011 1

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 2

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

General description Minitank assembly Closure assembly 2 Middle connection assy 271. 5 mm Minitank (short) assembly 202 mm 614. 35 mm Mock-up (damped) assembly NO EBW Closure assy 1 Frictional contact EBW 4

Assembly on tooling Nut Bearing Upper cap cover Upper eye -bolt Upper bolt Lateral eye-bolt • 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 • Threaded rod (M 16): connection between the upper and the lower cap cover. Holdingdevice Lateral eye-bolt Lower cap cover Lower bolt Nut • Lower cap cover: sustain PETS unit during the assembly on the tooling. • Lower bolt: fix lower cap cover and closure assy 1. • Nut (M 16): 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. 5

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 6

Assembly on tooling 5. The holding device is fixed 6. Clamping force is applied using a torque spanner 7. Tack welding 1 st FEM analysis: calculate gap variation in function of the applied load 7

Transportation 8. Rotation and transport to the EBW machine. 9. The holding device is removed. 2 nd 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) EBW Frictional contact EBW 8

Clamping force vs. Tightening torque TIGHTENING TORQUE (Ma) CLAMPING FORCE (Fv) Ma [Nmm] = Fv ·(0. 159·P + 0. 578·d₂·µg + 0. 5·d. Km·µk) = ~ 3·Fv [N] M 16 • P = thread pitch (2 mm) • d 2 = thread diameter (16 mm) • µg = friction coefficient of the thread (0. 15) • d. Km = average diameter of the bolt head (22. 16 mm) • µk = friction coefficient of the bolt head (0. 15) dkm 9

Welding EBW process Chuck Fixed V-support Bearing driven by the welding machine Ground 10

FEA Aim 1. Calculate the axial force necessary to hold the assembly on the tooling during the EBW process 2. 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 Maximum 50 k. N Minimum 0. 3 k. N 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)

Loading & Boundary Conditions Clamping force 1 st position 2 nd position Bearing condition -The selected ball bearing allows 10 (0. 17°) of rotation -Rotation due to gravity is allowed -Translation d. o. f. is fixed Gravity Fixed (Motor chuck) Fixed Gravity

Results – Axial force of 1 k. N Δgap max 1 µm Δdeflection 10. 5 µm

Results – Axial force of 2. 5 k. N Δgap max 2 µm Max. Stress 3 MPa Δdeflection 10. 8 µm

Conclusions ü On the basis of FEA performed, the selected clamping force is 2. 5 k. N, which corresponds to a tightening torque of 7. 5 Nm ü According to the results, the reduction of initial flanges gap (50 µm) due to the applied load is negligible. ü 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 TM 0. ü The highest stresses occur around the contact area close to the edge inside the adapter disk. For a clamping force of 2. 5 k. N the maximum value is less than 3 MPa (σY = 69 MPa)

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 16

General description Accelerating structure Super-accelerating structure Vacuum flange 484 RF flange Target sphere Cooling circuit RF waveguide Manifold Interconnection flange 2031 334 17

Brazing process BRAZING (Au/Cu 25/75, 1040 °C) 1. 2. 3. 4. 5. 6. 7. WFM WG cover + WFM WG body (x 32=4 x 8) Waveguide damping interface half 1 + half 2 (x 32=4 x 8) Stack type 1 (x 6) Stack type 2 (x 1) Stack type 3 (x 1) Manifold cover (tank int. ) + vacuum tube P 1 (x 8) Manifold small cover 3 + small cover 3 insert (x 32=4 x 8) BRAZING (Au/Cu 25/75, 1040 °C) 1. Manifold (hor) assembly (x 8=1 x 8) 2. Hor. manifold (mirrored) assembly (x 8=1 x 8) 3. Vert. manifold assembly (x 16=8 x 2) TIG WELDING 1. Manifold cover 2 assembly (x 8) BRAZING (Au/Cu 35/65, 1020 °C) 1. Structure type 1 (x 6) 2. Structure type 2 (x 1) 3. Structure type 3 (x 1) MACHINING 1. WFM WG brazed (x 24=3 x 8) 2. WG damping interface (x 16=2 x 8) BRAZING (Au/Cu 50/50, 980 °C) 1. Brazed stack 1 + AS cooling fitting adapters 2. Brazed stack 2 + AS cooling fitting adapters 18

Brazing process 1020 °C 900 °C Temperature history 19

Assembly on tooling Upper support Upper spring Lateral plate Lateral spring Lateral support Lower plate • 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. Nut Wedges Rod • 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. 20

Assembly on tooling 1. Graphite plate 5. Lateral supports, plates and springs 2. Disks stack 6. Upper support 3. Wedges 7. Rod 4. Manifolds 8. Upper spring and nut 21

FEA ü A static thermal and structural analysis with a temperature variation from 20 °C to 1020 °C was carried out for the accelerating structure ü The thermal expansion is constrained only by the springs, which are situated on the opposite sides of the fixed lateral support ü All the connections were considered ideally frictionless to reduce the computational time Tooling for the 1 st brazing step Free surfaces constrained by the springs Fixed surfaces connected to the lateral support (without springs) For the springs a constant stiffness of 20 N/mm was used Supported on the ground

Results – thermal expansion Max. in x-direction 4. 6 mm z Max. in y-direction 7. 2 mm y x Max. in z-direction 5. 3 mm

Results – stresses Max. 0. 1 MPa Stress due to thermal expansion

Conclusion ü On the basis of the FEA the displacements and the stresses due to thermal expansion have been calculated ü The transversal displacement of the manifolds is approximately 5 mm ü The axial displacement of the whole structure is approximately 5 mm ü 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