MICE Target Mechanical Design

Jason Tarrant – STFC» Working on upgrade of Target Mechanics

Contents» Main features of upgrade design» Progress & schedule for Target

Features of Upgraded Design Shaft changes

» Round tube lower section– 2x stiffness for same cross-section area– Simpler shape = easy to achieve

Machining of size & form (incl. inspection) Close fitting matched pair with bearing Fine surface finish of bearing regions Symmetry, incl. tip

Slot & fixingsfor read-out

vane

Doubleflat for

anti-rotation

4mmSolid Ti gr2 rod

5.95/4.55mmTi gr2 tube

Stop

Bearingsurfaces

Previous ‘+’ shaped lower

section

Features of Upgraded Design Shaft changes» Shorter length with extra dip depth

– Main body assembly shorter by 41mm, shaft tube section shorter by 31mm = +10mm dip depth

– 6mm also removed from upper rod section

» Balanced assembly– Vane balanced & 4 screws to hold (was 5)

» Reduced undercut for magnet– Increase stiffness of upper shaft

6mm shorter

4 fastenings Shallowerundercut

31mm shorter

Flat for anti-

rotation

Features of Upgraded Design Bearing alignment

» Clearance to be reduced as far as practical but dependant on:

– Manufacturing tolerances on shaft and bearing

– Bearing alignment (position and orientation)

– Straightness/shape of shaft

» Reduced clearance– Eliminate possible hammering of DLC

surfaces

– Constrain shaft motion to prevent off-centre loading Left: Revised design with round

holeRight: Old design with ‘+’

shaped hole

Revised upper bearing with rotation stop

Features of Upgraded Design

Bearing changes» Single piece main section with

doweled removable wedge (previous 2 or 4 way full split)

– High accuracy of bearing feature– Removable for DLC coating (line

of sight operation)

» Anti-rotation feature– ‘+’ design changed to round tube,

adjustable rotation stop incorporated to keep orientation of vane

Bearing hole

Removable wedge

Rotation stop

Dowel & angle faces for location

DLC set-up: wedge removed = line of sight

to bearing surface

Features of Upgraded Design Redesign of core assembly

» Tight bearing alignment guaranteed by decreasing core components & interfaces, and using metrology and dowels

– Stiff central core– Was 6 interfaces now 3– Was 5 components now 2

Bearings separated by many components & interfaces

Stator part of core, not independent

Clamp down on stator (possibility of uneven loading on weld and stator)

Only 2 components between bearings (Metrology aligned then dowelled)

Stator = independent assembly

Bearing extension reducing length of unsupported target shaft

Compact core with solid bolt together interfaces

Features of Upgraded Design Redesign of core assembly

» Lower bearing closer to beam to reduce unsupported shaft length = stiffer lower shaft section

» Simple alignment of bearing seats with use of Metrology then dowelled to locate

» Stiff bolt together design (replaces complicated clamp down)

» Self contained stator = can be built and tested independently of main core

Stator = independent assembly

Bearing extension reducing length of unsupported target shaft

Compact core with solid bolt together interfaces

Features of Upgraded Design Ruggedized & balanced vane

» Vane mass balanced mass about screw holes» 4 screws (not 5) = balanced mass of heads» Rugged single reset slot not delicate ‘finger’» Individual slots with guard edge

New balanced vane with guarded teeth and slot for reset

(not bent just way picture taken)Open tooth design of old vane and

finger reset

Recommendations from DLC Coater

Visit to Tecvac + communications- Recommendations for our design, as above +

- Use compatible polish- NO silicon based chemicals for manufacture- No spark erosion (excessive oxidisation) if necessary has to

be thoroughly treated- Materials and hardness OK for this application- Improved surface finish (current 1.6 Ra, 0.1-0.02 Ra pref)- No closed slots or holes, ‘line of sight’ process.- Differences in electro-potential can cause a build up so relieve

critical edges & corners and no burrs - 3-5μm thick recommended

Latest FEA – W Lau / S Yang Increased stiffness = higher 1st mode

» 1st mode previously 28-33 Hz with ‘+’ shaped shaft

» Now 50Hz (lower section) with new shaft shape and bearing support locations

QA - Mechanics

QC & Traceability on all manufactured parts» Materials certificates» Process trials and sign off» Copies of process data-files» Machine & hardware calibration» Metrology» Part marking» Etc...

Progress & Schedule

KeyLight Green = CompleteDark Green = In productionNo Highlight = Awaiting start

Progress & Schedule

2 Methods of shaft manufacture (6+6 max)» 1 Weld together stock parts and precision grind to size

– Can concentricity be maintained (tube ID/OD, tube – rod etc.)

» 2 Precision grind parts then weld together– Effect of weld on precision parts

Progress & Schedule 2 Methods of shaft manufacture

» 1 Weld together stock parts and precision grind to size

» 2 Precision grind & m/c parts then weld together

Effect of weld on precision parts?

Can concentricity be maintained when grinding (tube ID/OD, tube – rod etc.)?

Progress & Schedule

Conclusion All major & long lead items being manufactured, a

lot completed. Slight delay in shaft, longest lead item, will look for

shortcuts but not those that risk quality / function. Many processes on long lead items with external

contractors (welding, grinding, coating, heat treatment, wire erosion) control is not so easy, will be visiting a lot!

August / September installation still very achievable