Metrology for NCSX by wuyunqing


									Metrology for NCSX
Steve Raftopoulos and the NCSX
       Metrology Team
                       Metrology Systems

• Hardware:
   – Two laser trackers:
       • Leica LTD 500 (Interferometer and ADM unit) upgraded to EmScon interface
       • Faro Tracker X (ADM unit only)
   – Three Romer articulating arms – 12 ft length.
• Software:
   – Verisurf CAD-based 3D inspection software running on all hardware
     platforms. Metrology software built on top of MasterCam CAD?CAM
     software. Allows manipulation of CAD data and creation of layers for
     organization of metrology data.
   – Leica AXYZ and EmScon software available for interfacing and
     Diagnostics for Leica Laser Tracker.
   – Faro Utilities software for interfacing with Faro Laser Tracker
Coil winding and Initial Coordinate System
                      •   Coordinate system of coil is
                          established during coil winding
                          phase with the coil in a vertical
                          position in the ring.
                      •   Approximately 10,000
                          measurement points (taken with
                          Romer Arm) on winding form are
                          best fit to CAD geometry.
                      •   Coil is wound using this reference
                      •   Unfortunately, the coils are NOT
                          rigid bodies – they flex under their
                          own gravity load when the
                          support system is changed.
Field Period Assembly (FPA) Preliminary
                    •   Coil is placed on horizontal fixture
                        for measurements prior to sub-
                        assembly of 3 coils.
                    •   The coil is deformed using
                        wedge/lifting plates in order to re-
                        create the shape measured in the
                        coil winding fixture.
                    •   Reshaping error must be less than
                        0.005” (~0.12 mm)
                    •   Once acceptable reshaping is
                        achieved, the flange faces and
                        tooling balls (fiducial points) are
                        accurately measured.
FPA Measurements (continued)

              •   In order to characterize the entire
                  coil, at least three laser tracker
                  positions are required.
              •   A set of Global Fiducial points is
                  used to re-align to the coil. These
                  Global points were established
                  immediately after alignment to the
                  coil coordinate system.
              •   Re-alignment error (to global
                  points) must be less than 0.002”
                  RMS (0.05mm)
Integrity of Measurements

             • Laser trackers are checked
               daily by performing two-face
             • Laser tracker accuracy is
               verified by measuring a
               N.I.S.T. traceable length
             • Measurement data is validated
               by re-measuring alignment
               points after data collection.
               This verifies that the coil and
               laser tracker remained stable
               during measurement.
                Measurement Methodology

• Currently we are working with individual components.
• Alignment to known fiducial points on the measured part defines the
  coordinate system.
• Deflection of the part is a major concern.
• We fiducialize monuments surrounding the part and use these
  monuments to “leapfrog” around the part to obtain complete scan.
• In the future assembly of these components we will establish the
  machine coordinate system in the assembly hall and move the parts
  to the correct position.
• Deformation of the assembly of parts as well as deformation of the
  assembly hall will be important concerns.

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