Design of planar-flexure-based contacts for high-repeatability kinematic couplings

Abstract

This research assesses the effects of planar flexural elements on the repeatability of a high-precision kinematic coupling. Few devices exist that are capable of passive, repeatable nanoscale fixturing; this research facilitates the design of such devices by providing a more complete understanding of how flexural elements affect their performance. Improvements in coupling technology are expected to decrease production and assembly costs in a variety of industries where repeatable fixturing is required (e.g. the semiconductor, automotive, and tooling and machinery industries), and have the potential to improve the quality of research in a wide range of fields by increasing the speed and accuracy of manufacturing processes and metrology systems. Flexures serve to improve the performance of ball-and-flat contacts by preventing motion of the flats in the direction perpendicular to the contacts while allowing motion in tangential directions, thus reducing the effects of friction and wear at the interface. Flexural elements have been used to reduce hysteresis and prevent overconstraint in kinematic couplings but the use of planar flexures as friction and wear reducing devices has not been previously studied.

(cont.) A kinematic coupling that uses planar flexures was designed, constructed and tested. This coupling showed similar repeatability to a rigid coupling used as a control when the ball-and-flat contacts of both were free of wear; however, the flexure-based coupling performed much better than the control coupling after the contacts had been roughened by material failures resulting from repeated loading.