Mechanics of the IFMIF RFQ cavity - INFN Padovapepato/Busetto/IFMIF_PD_12062008 [Read-Only].pdf ·...

AP AP –– INFN PD INFN PD –– 12.08.200812.08.2008 11

Mechanics of the IFMIF RFQ cavityMechanics of the IFMIF RFQ cavity

Adriano Adriano PepatoPepatoforfor thethe

IFMIF EVEDA team IFMIF EVEDA team -- PadovaPadova

RFQ Preliminary Design Review

IFMIF EVEDA

Legnaro, 12 June 2008


The IFMIF EVEDA - INFN PD working group.

Mechanical engineering.

• Pepato Adriano (staff member)

• Dima Razvan (contract)

• Pasquetti Nicola (temporary)

• Romanato Marco (staff member)

Software:

• UG NX5 (CAD/CAM)

• UG NX NASTRAN Advanced Simulation

• ANSYS 11.0 Multiphysics

(OS: Windows XP, Linux)

Mechanical Workshop.

• Ramina Loris (staff member)

• Three technicians (two staff members and one contract)

Software:

• CAM PEP5 (Win XP on all the workshop machines)

3D Measumerements (contact and optical).

• Johansson TOPAZ 10 (750x600x500 mm)

• Mitutoyo A10 (1200x800x600 mm).

Software: JOWIN 10.0

Mechanical Workshop

EDM Machines

CMM Machines


Geometry of the RFQ cavity.The choice for a square transversal section presents some relevant implications (pros & cons):

Pros:

•Minimizing the total amount of power of the cavity (strong limit);

•Provides large surfaces for the positioning of all the vacuum lines and cavity accessories as power couplers etc;

•Gives a reduced request of raw material to obtain the final shape of the components.

Cons:

•Offers a limited stiffness under vacuum service condition (the shape will deform under bendingbetter than membrane behaviour as for a circular shape);

Schematic layout of the RFQ line.RFQ Module: connection side.


There are some peculiar aspects of the IFMIF RFQ cavity withreference to some other experiences as TRASCO, SNS, LINAC4:

• The transversal overall dimensions (nonetheless the longitudinalone..) are considerably higher

e.g.: TRASCO De=250 [mm], IFMIF De=630 [mm].

•The vane tips have a 3D configuration (this requires a more accurate and time expensive milling with relevant demands on the machine configuration and on the working cycle).

• The procurement of the CUC2 raw material blocks is limited bythe total mass amount (so that for an assumed transversal shapethe longitudinal one is fixed) . We assume CARLIER S.A. as uniquesupplier capable to fullfil all the design specs in terms of purity and grain size.

• The module weight and geometry is also limited by the brazingowen capabilities. We assume to continue the partnership with the CERN brazing lab (ref. Serge Mathot) and that implies:

•Total mass allowed roughly 700 kg (for both the vertical and the “smart” new horizontal owen).

• The overall dimensions must stay within a cylindrical volume of D=650mm L=1500 mm).

Peculiar geometrical constraints of the IFMIF EVEDA RFQ Cavity.

3D model of the vane tip

RFQ module: 1100x410x410[mm]


• Very demanding on the stability of the design geometry: • very limited deformations accepted under the vacuum condition (<1μm);• very limited deformations in the service conditions due to the thermalexpansion (<10μm);• uniform shape deformation along Z (beam axis) particularly in correspondanceof the bolted joints (modules connections) and of the vacuum openings.

• Very demanding in terms of overall mechanical tolerances on the single components(typically 10 μm for milling machining);• strong limitation on the alignment requirements:

• vane tips alignment < 10 μm.

Geometrical constraints (cont.)

At this design study we are developing a solution that considers:

• a square transversal section with a minimum wall thickness (th= 35 mm) ableto fullfil the requirements for the cooling duct housing, the seats for the flange bolts and the required reduced deformation under vacuum, whileoptimizing the total module lenght;

• a thicker transversal current section (th=46.5 mm) limiting to a few micronsthe under vacuum deformations (with a 25% of module length reduction);

• a more intrinsecally stable transversal section (a somehaow standard optagonal shape, th=35 mm) with an optimized ratio of the sides length(housing of vacuum openings tws vane tips displacements).


Brazing constraints.

All brazing connections “must be” horizontal.

Need to limit the total number of brazing (Nb) for a component: Nb,MAX=2 (for specific problems Nb,MAX=3).

Components must be annealed before any milling machining (a schematicworking sheet will be proposed later in the presentation)

All components must be geometrically certified (CMM 3 D measurement) before and after each brazing step.

The large number of operations to be performed with the brazing oven and the large committment of the CERN installation induces (forces) toconsider to start a parallel production with the brazing facility of the LNL.

Limits:

• limited experience;

• update of the brazing facility;

• characterization of the system up to a confident experience for a specific production. Nevertheless all the annealing steps will be performedat LNL.

• The geometrical aspect (1000x1000x1650 mm) and the mass (1000 kg) limit are less critical.

LNL brazing owen


Mechanical Design Guidelines.With reference to all the geometrical contraints reported before weassume to produce sub-modules of about L=550 mm that will be brazedtogether with the bolted flanges to about modules of a total L=1100 mm.

Total number of modules: 8+2 (two special modules of L=500 mm for the end-caps).

To minimize the use of Ultra-pure CU and to limit the induced stresses on the raw material weassume to rough-cut the shape of the sub-module components from a starting block of about500x280x570 mm using a EDM. We consider a finishing stock of about 1 mm (to compensate the shape changes after the annealingstep @600 C).

This approach will also minimize the finishing milling time and the total energy transmitted to the sub-modules components.

Limits: CARLIER S.A. is capable to supply now a length of about 400 mm. The new installation(operative mid ’09) will allow to satisfy for the requested needed length of 600 mm).

NESTINGSub-module components.


Some reference numbers:

Carlier actual limit for the supplied raw material:

• 500x280x400 [mm] goal 500x280x580 [mm]

• W=500 kg W=730 kg

• delivery time: 3 weeks/depart usine

• Nr. of blocks needed for a prototype unit:4

• Module weigth:

Th,skin=35 mm Th,vane=(30-80) mm; Ltot=1100 m

Overall weigth (CF100, coupling flanges,etc) W=(633-800) k

(We need to consider the weigth of the toolingneeded so that the total estimated W=850 kg).

Th,skin=46.5 mm Th,vane=(30-80) mm; Ltot=800 mm


EDM technology.We have performed several tests with EDM machining:

• rough shaping machining (AGIE-Charmilles, Sodick, Mitsubishi)

The maximum heigth of the cut could be H=600 mm (Mitsubishi, Sodick).

Some datas: maximum cut speed for H=550 mm

• special cutting wire D=0.3 mm Cs=0.22 mm/min

• special cutting wire D=0.36 mm Cs=0.3 mm/min

Mechanical tolerances: ±0.05mm (H= 550 mm)

• Ultra-finishing (up to a roughness of about 0.6 μm and a planarity less than 0.01 mm)

• The tests where performed on a smaller Heigth (H=300 mm) and the overallmachining time (rough cutting and ultrafinishing for a total number of passes=5) increases only about a 50%.

• Extensive 3D measurements were done on the samples (Mitutoyo CMM).

Problems:Surface contamination extended up to 10 Ra (6.0 μm) and all polluants could be removed by a

Quick treatment (few seconds) in an acid based bath.

We cannot use electro-eroded finishing for the surfaces to be brazed.

Conclusions: we consider the EDM approach only for the rough cutting and for the recoveringof damaged components or to modify the cavity shape of the submodules whereas needed.


3D milling machining.

The requirement for a 3D vane geometry isquite time demanding for the milling machining.

We have performed several tests on samples of L=280 mm with a spherical tool (some detailsare reported in the following).

The roughness measurement was done in the Metrological Lab @CERN (Didier Glaude) with aninterferometer machine.

Some datas:

• Diameter of the miller ball: D=12 mm;

• Transversal milling step I=4 μm;

• Working time: 3 hours.

The timing estimate for the milling of each sub-module will be done only via a CAM basedsimulation.

AP AP –– INFN PD INFN PD –– 12.08.200812.08.2008 1111ρ and R0 (cm) as function of RFQ Length, the ratio is 0.75

2D modulation 2D modulation3D modulation


Position 1

12


Position 1

13


General design assumptions.

The design and production phases of the RFQ cavity production need a very carefull R&D phase. We aim to start to produce a module prototype and to complete it by July ’09.

We assume to develop all production phases ‘in house’ providingthe Mechanical Workshop of Padova with two machines that willcover all the requirements needed, essentially:

• EDM with an allowable Z=600 mm

• Milling machining center with 4 axis

Since we have not enough space to locate the new machines weare building a new shed close to the MW with a specificambient conditions, a crane etc.

The tender for the construction is approved and the definitionof the milling machining center features are fixed.

We aim to have all these machines installed and operative bythe beginning of 2009, while in the meantime the prototypeconstruction will be done with the existing machines.


NEw

SHEd


Milling machining center (schematics).


Preliminar job card (sub-module).

• Procurement and qualification of raw material (CUC2) CARLIER S.A. Dim.:500x280x400 [mm] (prototype) – Final: 500x280x570 [mm]

(The material specs and qualification will be defined in collaboration withthe TS/MME CERN Group (ref. Stefano Sgobba). An ultrasonic test willverify the grain size and uniformity.

• Rough finishing of the block (Carlier).

• Deep Drilling of the cooling ducts (blind ended) (outsourcing).

• Rough cutting of the sub-components via EDM (OM-PD).

• Annealing of the sub-modules components @T=600 ºC (Brazing oven LNL).

• Milling machining with a 4 axis milling machining center (OM-PD) (all final machining apart from the 3D vane tipand the finishing surfaces for the brazing).

• Annealing of the sub-modules @T=600ºC (Brazing oven LNL).

• 3D machiing of the vane tip and finishingof the brazing coupling surfaces.

• 3D CMM test

• Chemical cleaning.


Preliminar job card (sub-module) (cont.)

• Assembly of the sub-componets in the clean room (3D check).

• Brazing of the sub-module @ 850 ºC (CERN Mathos Lab).

• coupling of the subcomponents;

• brazing of all cooling duct taps;

• brazing of all the CF100 connections (this step could beintegrated also in the 2° brazing step)

• 3D CMM qualification test (IFMIF LAB@LNL).

1° brazing step (sub-module).

Brazing connectionslines for a sub-module


Preliminar job card (sub-module) (cont.)

Test of the Cooling lines:

•Vacuum leakage (He leak test);

•Pressure test of the lines.

Milling machining of the caps

Milling finishing of the sub-modules end-faces

• preparation of the flange housing;

• finishing of the brazing surfaces;

• finishing of the bolt seats.

3D CMM verification

3D CMM alignment of the 2 sub-modules.

2° brazing cycle @800 ºC

3D CMM verification

Milling machining of the module endcaps

• machining of the stainless steel cut of the coupling flanges,

• endcaps corrections (whereas necessary).

Brazing connection


The Sub-Module cooling system.Design guidelines.

• Need to separate the cooling lines for:

• vanes

• cavity skin.

• Minimize the Δf of the cavity

• Minimize the temperature gradient along Z.

• Collect all the cooling connections far from the bolted flanges to allow for a better access and toavoid accidental damage of the brazed connections.

• Provide an independent cooling system for eachsub-module to allow for a complete commissioning of the cooling lines before the 2° brazing step.

• Minimize the contact surface between the coolinglines and the sensitive volume (limit any dropage of water in the cavity in case of leakage).

• Maintain a minimum distance between the ductsand the inner cavity skin (e.g.: 5 mm).

• Avoid passing through ducts/brazed surfaces.

• Minimize the vane tips deformations.

VaneS

K

I

N


The Vane cooling ducts (schematics).

INvane

OUTvane


The Skin cooling ducts (schematics).

Skin corners:

4 ducts1IN/1OUT

2 Taps

Skin middle:

4 ducts 2IN/2OUT

Skin corners:

4 ducts1IN/1OUT

2 Taps


Skin corner IN/OUT crossing

Skin corner

blind connection


Preliminar design of the Hydraulics (schematics).

This represents a simpleexercise for the overalldimensions of services as:

• vacuum manifolds (on the two sides with a minimum impedance);

• power coupler, tuners (on the two sides);

• cooling lines (preferablyon the bottom with a common IN/OUT);

• easy access for modulesassembly, bolt flangesetc.


What next:

• fix the geometry of the cavity;

• tender for the material procurement (funds available);

• machine acquisition;

• close definition of the milling machining working cycle;

• design of the services lay out.

Mechanics of the IFMIF RFQ cavity - INFN Padovapepato/Busetto/IFMIF_PD_12062008 [Read-Only].pdf ·...

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