Effect of Ceramic Ball and Hybrid Stainless Steel Bearing/Wheel Combinations on the Lifetime of a Precision Translation Stage for the SIM Flight Project

摘要

A study of hybrid material couples using the SpiralrnOrbit Tribometer (SOT) [1]-[3] was initiated torninvestigate both lubricated (Pennzane~? X2000 andrnBrayco? 815Z) and unlubricated Si3N4, 440C SS, Rexrn20, Cronidur X30 and X40 plates with Cerbec SN-101-rnC (Si3N4) and 440 C balls. The hybrid wheel/bearingrnassembly (Figure 2) will be used on the Linear OpticalrnDelay Line (LODL) stage (Figure 1) as an element ofrnthe NASA Space Interferometry Mission (SIM). SIMrnis an orbiting interferometer linking a pair telescopesrnwithin the spacecraft and, by using an interferometryrntechnique and several precision optical stages, is ablernto measure the motions of known stars much betterrnthan current ground or space based system. Thisrnmeasurement will provide the data to "infer" thernexistence of any planets, undetectable by otherrnmethods, orbiting these known stars.rnThe LODL is a motor driven, band drive rail systemrncarrying a Corner Cube Retro-Reflector Carriagernsystem running on a 1.54 m guide rail system wasrnconceptualized. Three Integrated Hybrid DuplexrnAngular Contact Bearing Wheel Assemblies (Figurern2), running on the precision rail system, are used tornlocate the carriage system on the rail, with preloadrnwheel assemblies opposite to these assemblies. Thernrequirement is a 5-year mission lifetime with a goal ofrn10 years total, using little or no lubricant in order tornreduce contamination to the nearby optics. The SOTrnresult indicates accelerated lubricant consumption raternbetween the ceramic ball and 440C SS and 52100rnbearing steel, but promising trend with the newerrnCronidur X30 and X40 bearing steel. The use of dryrnor no lubricant will require further investigation.