Post on 21-Jan-2016
CM25 Engineering 1 4 Nov 2009
DIFFUSER
Carousel (~50kg)Driven by air motors – 3 separate ‘actions’1. Carousel rotation2. “30 degree rotation’’
Transfers discs from carousel to carrier3. Carrier
Moves disc in/out of solenoid
CM25 Engineering 2 4 Nov 2009
STATUS – 3 Nov 2009
Mechanics reassembled– Survived basic tests
– more required including: Motor speedsPositioning accuracy Bedding-in of gears….
Electronics & Air Crates working
LabView controls starting (EPICS can wait)
Developing disc transfer operation – critical item
– next slides
CM25 Engineering 3 4 Nov 2009
DISC TRANSFER
Disc Holder Disc Carrier
Carousel rotation
D-H Rotation Carrier motion
Discs transferred between Disc Holders and Carrier
Each disc has 4 pins on each side to fit 4 holesEach disc has 2 SidesThere are 5 DiscsEach has (up to) 4 Orientations
160 pins & holes to align reliably & reproduciblyor something will bend / break / jam
Pin – hole clearance is +/-- 0.5mm
3 sigma positioning < 0.5mm
Position to < 0.15mm for varying loads on Carousel
CM25 Engineering 4 4 Nov 2009
DISC TRANSFER OPERATION
Need to understand this in detail
Forces & reactions
Potential fouls
Friction?
Some latches for pins will help
Being developed
Space is limited
CM25 Engineering 5 4 Nov 2009
• Not easy to achieve required accuracy of 0.15mm or better• Air motors overrun (but deliberately very slow now)
• Now use piston to align Carousel arm• Measured misalignment is ~ 0.5 mm
• Depends on load (lead is heavy)
• Design was not tolerant of any misalignments• Have incorporated float + springs in carrier
• for L – R and U – D misalignment (1mm / 0.3mm)
• Developing overrun & locking mechanisms for discs• Keep pins aligned in disc-holders & absorb overruns
• More springs… .
• Building mock-up of Disc-Holder – Carrier arrangement• Test various ideas for locking the pins • Develop transfer procedure – invisible on real device
• Allowed 9 weeks in schedule for this (& other tests)• May need more inspiration & imagination
• Transfer operation development on critical path
CM25 Engineering 6 4 Nov 2009
DISC XFER MOCK-UP & PIN-LOCKS
CM25 Engineering 7 4 Nov 2009
STILL TO DO
Hardware– Install & commission:
– Shaft encoder read heads– Black / gold rings for disc-holder alignment
Firmware– Develop FPGA firmware & RS232 interface
– Incrementally
Software– Develop LabView controls
– In parallel with firmware
Once LabView controls developed migrate to EPICS– Would be a distraction at present
CM25 Engineering 8 4 Nov 2009
SOME OTHER CONCERNSCompressed air pressure in Oxford is rather low
– Would like > 6 bar; can get 4 – 5 bar depending on other users– Need to understand how speeds depend on P
– Can possibly improve a bit– Motors run a bit slow
Hope overruns are small & do not depend critically on pressure
Installation on Spectrometer Solenoid– Flatness of end plate (align to small fraction of mm…)
– Awkward; may need shimming
Operation in magnetic field– Most – but not all – ferromagnetic components eliminated
– esp. v. small bearings in gear boxes on motors– Have spare motors; run with field off ??
Quenches– Potentially large forces
– Distortion & loss of critical alignment
CM25 Engineering 9 4 Nov 2009
ASPIRATIONAL SCHEDULE