Alignment of Magnet Apertures

1
Alignment of Magnet Apertures Surveying with
Leica Laser Tracker Module

• B.Sasidhar Rao
• Shradha Palod
• Raghavendra Gangoor

2
Warm Measurements with Laser Tracker Module

• Alignment of magnet with bench at CFB and MRB
  sides.
• Required when magnetic measurements are done on a
  magnet , eases insertion of shaft
• Especially with SSSS, when the bench is not
  exactly confirming to the magnet geometry
• Surveying
• Required with SSW measurement to find the
  position of stretch wire

3

• LASER Tracker Module

• The laser tracker is a transportable 3D measuring
  system, measuring vertical and horizontal angles
  as well as interferometric or absolute distances.
  
• The laser tracker used is the LEICA LTD 500.
• Consisting of the central Tracking unit, LT
  Controller unit, Reflectors, application s/w,
  Level meter, Laptop, hardware lock etc.

4
Introduction to measurement with Laser Tracker

• This is Laser Interferometer which tracks a
  moving retro-reflector via a motorised mirror
• Permits real time distance measurements
• Once the laser beam locks onto the reflector it
  tracks and displays reflectors position
  continuosly until the beam is broken
• Reflectors used for different applications
• Corner Cube Reflector (CCR)
• Tooling Ball Reflector (TBR)

5
Trilateration principle(2D)
St.Genis
3
8
1
Checkpost
Gare Cornavin
SM-18
6
Alignment of Magnet with Leica Laser Tracker
7
Features of Laser Tracker

• Fully automatic tracking system as a huge amount
  of magnets has to be measured
• Automatic measurement inside a tube of 50 mm and
  15 m length
• An accuracy better than 0.1 mm and reliability
  using redundancy
• Transportability as the works take place in
  different places

8
Requirement for magnet alignment

• Dipoles
• Compliance to geometric tolerance limits
• To check bended shape (tolerance is /- 1mm) for
  mechanical aperture
• To measure position of alignment references
• Quadrupole
• To facilitate smooth insertion of shaft for
  magnetic measurements
• Requirements
• Compliance to geometric tolerance limits
• High Precision
• Measurement Portability
• Solution
• Laser Tracker along with suitable Mole

9
Alignment Procedure

• Leica Set up
• Orient to Gravity
• Measurement
• Analysis of result

10
Leica Set up

• Warm up of Laser takes about 15 min
• Start temperature and pressure monitoring
• Fixing position of Leica so that tracking is
  possible till the end of the magnet without
  losing the beam
• 2 to 3 iterations are required for exact
  positioning.
• Levelling

11
Orient to Gravity

• Orient to gravity is done using NIVEL level
  sensor
• It is used to set leicas primary( standing) axis
  very close to gravity (vertical)
• Any residual tilt is compensated by correcting
  the measured angles such that they appear to come
  from an exactly levelled instrument

12
Measurement

• Creation of Station for each measurement
• Select the type of reflector being used
• Install mole in the magnet aperture and attach
  reflector on the mole

Mole
Reflector
13
(No Transcript)
14
Analysis of Result

• After the leica scans for the full magnet length,
  the results are available for analysis
• Translation of co-ordinate axis is done such that
  (0,0,0) point is transformed onto the CFB of the
  magnet aperture for which alignment is carried
  out
• Plotting the results in the excel sheet for
  analysis
• Repeatation of the measurement till alignment is
  within acceptable tolerance ( lt 2mm)

15
(No Transcript)
16
(No Transcript)
17
Surveying of Magnet axis with Leica Laser Tracker
18
Aim

• A laser tracker system is used to survey the SSW
  system and the magnet in order to link the
  magnetic axis to the magnet fiducials
• By this one can get exact location of stretch
  wire inside the magnet, which is used to compute
  the magnetic axis
• Global Survey Accuracy 50-100 microns

19
Surveying Procedure

• Build a network of points in 3-D space
• As it is impossible to see all fiducials of
  both SSW stages and magnet from one single
  location, the entire survey is performed from two
  different positions
• Installation of Leica and survey at CFB side
• Installation of Leica and survey at MRB side
• Analysis of measured data

20
Building a network of 3-D points in Space

• Points used for networking should be carefully
  identified
• The points should be such that at least 3 common
  points are visible from both the stations. A
  large number of points should be measured for
  better accuracy
• The points should be stable, fix and should not
  be disturbed till the entire measurement is
  completed

21
Stage B Survey Points
Stage A Survey Points
22
Stations Location
Tracker location for station 1
23
Definition of measurement points
24
Surveying of network points
Station at MRB Side
Station at CFB Side
Surveying of fiducial points
25
Installation of Leica and Survey at CFB side

• Set up of Leica - as already explained
• Orient to Gravity
• Static measurements of network points, magnet
  fiducials and SSW stage-B X Y positions
• In Static measurements, the distance between home
  position (bird bath) of tracker and the
  respective point is measured
• Depending on the location of measuring point ,
  appropriate reflector holder should be chosen

26
Installation of Leica and Survey at MRB side

• Set up of Leica
• Has to be repeated since the position of Leica is
  changed
• Orient to Gravity not required
• Static measurements of network points, magnet
  fiducials and SSW stage-A X Y positions

27
Analysis of measured data

• Orient to network
• As soon as all points have been measured on the
  two stations, a network orientation is required,
  to set all points in one referential
• Solving the network to achieve Axis Alignment
• For the magnets fiducials to become the
  coordinate system of the measurement

28
(No Transcript)
29
Thank You