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Review on collimator movement with stepping motors

This review discusses the mechanical design, motion of collimator jaws, auto retraction system, and SPS test results regarding the movement of collimators with stepping motors. Detailed analysis of results and conclusions provided.

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Review on collimator movement with stepping motors

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  1. Review on collimator movement with stepping motors Mechanical design and SPS results O. Aberle 4th November 2005Design work from many colleagues in TS/MME, Stefano Redaelli for the SPS test resultsPhotos from P. Francon Review on collimator movement with stepping motors

  2. Overview • Mechanical design • Motion of collimator jaws • Auto retraction • SPS tests • Results from SPS tests • Results on Prototype No. 3 • Conclusions Review on collimator movement with stepping motors

  3. LEFT M1 M2 UP DOWN Beam M3 M4 RIGHT 14 devices to move / control jaw positions and gap opening Mechanical design For each collimator: 4 motors + 4 Resolver + 4 jaw positions + 2 gaps Stepping motors Precise in relative (5-10mm) but may loose steps Resolvers Count the steps of motor. Decoupled from mechanical structure (cannot see mechanical plays!) External measurements (potentiometers, LVDT’s, palmers): measure directly jaws Our approach: Adjust the motor settings. Use the (calibrated) external measurement devices as a reference in the control room. Review on collimator movement with stepping motors

  4. Mechanical design Vacuum tank Inside gap Outside gap Each collimator measured open in metrology: -Full gap-Mech. stop/Jaw surface Movement Mechanical end-stop Review on collimator movement with stepping motors

  5. Motion of collimator jaw Torque meter Vacuum tank CFC jaw Cooling pipes Glidcop bar Sliding tables Transmission Motor Precision screw Return spring Review on collimator movement with stepping motors

  6. Motion of collimator jaw Review on collimator movement with stepping motors

  7. Motion of collimator jaw End stop Return spring Sliding table Coupling Motor axis Screw support Precision screw Motor support Review on collimator movement with stepping motors

  8. Auto retraction, Angle limitation Motor Rigid barRack and PinionPin hole/slot (3mm) Return spring Review on collimator movement with stepping motors

  9. Auto retraction, Angle limitation • Auto retraction • One system: 2 sets of springs (dia. 5 and 6.3 mm) available • for 3 types of collimators (CFC, CU and W jaw material) • for 4 different orientations (0, 90, 45 and 135 °) • Works in case of power cut (condition: Mechanics Ok) • Tested vertically with 15 kg loaded (Tungsten case) • Limitations: To start movement, minimum spring pre-load needed • Back up: One motor can drive the jaw out against the angle limitation system • Angle limitation • Given by the mechanical play (3 mm on 1 m jaw length) • Blocks the angle (with powered motor) Review on collimator movement with stepping motors

  10. SPS tests Transmission to jaw Resolver Motor Side view Potentiometer View from bottom Different sensor installation for SPS and TT40 prototypes… LVDT Review on collimator movement with stepping motors

  11. Results from SPS tests Review on collimator movement with stepping motors

  12. Measurements at the metrology Absolute error with this setup  3 mm Review on collimator movement with stepping motors

  13. Results from SPS tests • Potentiometers: Resolution  40-50 mm (some sensor better,  20 mm) • Resolvers: absolute error  80 mm (expected 5 mm). For motor control (lost steps?) • LVDT’s: Resolution  15 mm in laboratory tests.(re-calibrations regularly needed - feasible for > 500 sensors in radiation environment?) • Capacitive sensor: Resolution  1 mm; not radiation resistant  Mechanical play: 40 mm for SPS prototype 10 mm for TT40 prototype Minimum step for jaws = 5 mm Review on collimator movement with stepping motors

  14. Preliminary results from Prototype 3 “Soft” point? Review on collimator movement with stepping motors

  15. Preliminary results from Prototype 3 Deviation from target over full range: 50 mm Palmer (±3 mm),hand aligned No vacuum,open collimator,No RF contacts Review on collimator movement with stepping motors

  16. Conclusions • Reproducibility of the jaw position: <10 mm • Mechanical play:  20 mm • Absolute position knowledge in laboratory:  100 mm = 0.5 s(full mechanical chain) (LHC, top energy) • Alignment in tunnel: 0.1 to 0.2 mmEach axis might need a calibration curve • Open points: Test the different orientations • Life time/ cycling • Effect vacuum Determine safety margin for each type and orientation • Risks: Alignment screw/motor, wear and aging, limitation in auto-retraction, • Safety factor of 2 desirable Review on collimator movement with stepping motors

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