Merlin EPU Support and Drive System Design Review

Merlin EPU Support and Drive System Design Review Steve Marks Mark Coleman 4/26/06

Scope of Review - Mechanical System • Frame – Deflection • Bearings and Mounts – Deflection – Load Rating • Drive Screws – Load Rating • Backing Beams • Motor Torques

Other Reviews • • Magnetic structure – 2/2/06 Motor Control System – TBD? Sector 4 EPBI – TBD APRP – Scope – Installation Readiness

EPU 90 vs. EPU 50 (old) EPU 90 (new)

EPU 90 vs. EPU 50 (old) EPU 90 (new)

What is New? • 90 mm Period (three previous EPUs are 50 mm) • 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

EPU 90

EPU 90

EPU 90

EPU 90

Vertical Drive • Drive Screws: – Max. load per screw = 17 k. N – Static load rating = 107 k. N (static), – Mean load ~ 10 k. N – Dynamic load rating = 27 k. N (dynamic) • Linear Roller Bearings – Moment load = 2. 7 k. N-m – Rating = 7. 2 k. N-m

Vertical Drive • Torque/speed – Max torque = 1. 2 N-m – Max speed = 1500 RPM • Motor rating (with EPU 50 motor) – Cont. Stall Torque = 3. 9 N-m – Rated speed = 1500 RPM

Deformation due to Vertical Load

Vertical Drive • Drive screw mounting is over constrained affected by deflection of frame and bearing mounts. • EPU 90 vs. EPU 50 Scaling Comparison: – Vertical columns: • Vertical load: F 90/F 50 = 2. 3 • Frame column stiffness: I 90/I 50 = 6. 5 • Deflection: 90/ 50 = 0. 35 – Duplex bearing mounts • • Moment: M 90/M 50 = 1. 9 Stiffness: I 90/I 50 = 2. 0 Length: L 90/L 50 = 0. 8 Deflection: 90/ 50 = 0. 67

Backing Beam Deflection

Backing Beam / Horizontal Drive Deflection Test Setup

Backing Beam / Horizontal Drive • Cross Roller Bearings: – Load per roller = 1. 0 k. N – Bearing load rating = 3. 9 k. N • Torque/Speed with 5/1 gear ratio (3/1 on EPU 50): – Max. torque = 2. 1 N-m – Motor rating (using same motor as EPU 50): • Cont. Stall Torque = 3. 9 N-m • Speed limit = 900 RPM vmax = 10 mm/sec (~10 secs. to switch polarization)

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