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Merlin EPU Support and Drive System Design Review

Steve Marks

Mark Coleman

4/26/06

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Scope of Review- Mechanical System

• Frame – Deflection

• Bearings and Mounts– Deflection– Load Rating

• Drive Screws – Load Rating

• Backing Beams

• Motor Torques

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Other Reviews

• Magnetic structure – 2/2/06

• Motor Control System – TBD?

• Sector 4 EPBI – TBD

• APRP– Scope– Installation Readiness

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EPU90 vs. EPU50

EPU50 (old) EPU90 (new)

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EPU90 vs. EPU50

EPU50 (old) EPU90 (new)

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What is New?

• 90mm Period (three previous EPUs are50mm)• Separate mounting of block/keepers

– Avoid correlated motion causing shift dependent skew quad• Modified backing beam

– Bearings closer to load– Horizontal drive closer to load– Steel backing beam

• Stiffer Frame– To accommodate ~ 2.3 vertical load

• Mount encoder directly to backing beams• Harmonic drive coupling on vertical screws for taper

adjustment• Modified gear ratio for horizontal drive

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EPU90

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EPU90

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EPU90

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EPU90

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Vertical Drive

• Drive Screws:– Max. load per screw = 17 kN– Static load rating = 107 kN (static), – Mean load ~ 10 kN– Dynamic load rating = 27 kN (dynamic)

• Linear Roller Bearings– Moment load = 2.7 kN-m– Rating = 7.2 kN-m

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Vertical Drive

• Torque/speed– Max torque = 1.2 N-m– Max speed = 1500 RPM

• Motor rating (with EPU50 motor)– Cont. Stall Torque = 3.9 N-m– Rated speed = 1500 RPM

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Deformation due to Vertical Load

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Vertical Drive

• Drive screw mounting is over constrained -affected by deflection of frame and bearing mounts.

• EPU90 vs. EPU50 Scaling Comparison:– Vertical columns:

• Vertical load: F90/F50 = 2.3• Frame column stiffness: I90/I50 = 6.5• Deflection: 90/ 50 = 0.35

– Duplex bearing mounts• Moment: M90/M50 = 1.9• Stiffness: I90/I50 = 2.0• Length: L90/L50 = 0.8• Deflection: 90/ 50 = 0.67

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Backing Beam Deflection

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Backing Beam / Horizontal Drive

Deflection Test Setup

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Backing Beam / Horizontal Drive

• Cross Roller Bearings:– Load per roller = 1.0 kN

– Bearing load rating = 3.9 kN

• Torque/Speed with 5/1 gear ratio (3/1 on EPU50):– Max. torque = 2.1 N-m

– Motor rating (using same motor as EPU50):• Cont. Stall Torque = 3.9 N-m

• Speed limit = 900 RPM vmax = 10 mm/sec (~10 secs. to switch polarization)

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Procurement/Fabrication Plan

• Proceed with procurement of drive screws (long lead – critical path on schedule)

• Initiate fabrication of backing beams, frame, etc.

• Proceed with control system procurement after control system discussion/review