Abstract

UltraForm Finishing (UFF) is a production-level optical polishing process consisting of a moving belt that is pressed into an optical surface by a carrier wheel. The current configuration is comprised of a cylindrical carrier wheel attached to cylindrical roller bearings. As the optics market is moving towards aspheric geometry with smaller radii of curvature, geometric limitations associated with roller bearings requires the development of a modified approach to the UFF process.

This thesis explores the feasibility of incorporating spherical fluid bearing elements in the UFF process as a replacement for roller bearings. Self-acting (or wedge film) and externally pressurized hydrostatic spherical fluid-film bearings were investigated for the UFF process. The self-acting bearing was modeled and analyzed using a previously developed hydrodynamic finite element computer program. The hydrostatic bearing was modeled using an analytical formulation of the Reynolds equation coupled with empirical data to account for entrance flow effects at the feed hole and to account for pressure drops in the bearing fluid supply system. Both bearing configurations predicted adequate fluid film thickness under steady load and speed.

Performance tests on the UFF were completed with both bearing configurations under steady load and speed. Ball to cup seizure was observed with the self-acting configuration nearly immediately after initial load and speed application, with seizure presumably due to inadequate squeeze film resistance during the transient startup period. The hydrostatic bearing operated successfully over a wide range of applied loads and speeds employed in the current UFF process with minimal cup and ball wear. The feasibility of the hydrostatic spherical bearing element in the UFF process was subsequently demonstrated through the generation of repeatable and acceptable removal function maps which were then employed in the polishing of a planar optical surface.

Library of Congress Subject Headings

Grinding and polishing; Bearings (Machinery); Fluid mechanics; Optics

Publication Date

11-24-2014

Document Type

Thesis

Student Type

Graduate

Degree Name

Mechanical Engineering (MS)

Department, Program, or Center

Mechanical Engineering (KGCOE)

Advisor

Stephen Boedo

Advisor/Committee Member

Agamemnon Crassidis

Advisor/Committee Member

Mario Gomes

Comments

Physical copy available from RIT's Wallace Library at TJ1280 .D44 2014

Campus

RIT – Main Campus

Plan Codes

MECE-MS

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