Primeri fretinga v sodobnih strojih in napravah

M. Kalin, J. Vižintin

Strojniški vestnik 45 (1999) 185–198.

Abstract

Freting se lahko pojavlja v vseh primerih, kjer so stiki izpostavljeni vibracijam, spreminjanju napetostno-deformacijskega stanja, ki omogoča relativne pomike, termičnim spremembam idr. Že relativni pomiki približno 0.1 mikrometra lahko povzročijo porušitev elementa zaradi fretinških poškodb ,kar pomeni, da je freting zelo težko v celoti odpraviti. V prispevku so predstavljeni nekateri značilni primeri, kjer prihaja do fretinških poškodb. Ker pa se v novejšem času v strojih vse pogosteje uporabljajo visoko zmogljive keramične komponente, je vse več primerov fretinških poškodb na spojih med keramiko in jeklom. Zato so predstavljeni tudi najpogostejši primeri, pri katerih se freting pojavlja v nosilnih dotikih med jeklom in keramiko iz silicijevega nitrida.

Fretting conditions are found in practically any technical system where contact vibrations are present, or where the contact stresses are induced by cyclic accelerations, fatique stresses, acoustical noise or temperature variations, thus enabling small relative motion. It is known that even reciprocating movements as short as 0.1 mikrometra in amplitude can cause failure of e component. This means that fretting is very difficult to completely prevent. Recently, high performance ceramics are increasingly used in modern machinery. Consequently, more frequent occurrences of fretting between the ceramics and steel - the prevailing engineering material - are expected. The ceramic material which is used most frequently in applications where fretting could occur is silicon nitride, and therefore it deserves the most attention. In this paper, the most common application where fretting occurs between the steel and silicon nitride ceramics are presented.

Keywords: fretting, steel, ceramics, silicon nitride Akcije

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