Failure analysis of chain bracket

Abstract

In spite of numerous and expensive research in the field of fatigue and fracture and regular control of end products, cracks occur every day in all fields of human activity. This paper describes failure analysis of chain brackets, used in conveyor systems for cement production. Chain type bucket elevators utilize chain brackets for joining segments of chain as well as for attaching brackets for bulk material transport. The contact zone between chain link and bracket is one of the most stressed in this elevator system. During regular maintenance, cracks are found on used and new brackets in the case hardened zone. Case hardening of the chain bracket is performed due to requirements for increased wear resistance of the chain link contact. The occurrence of cracks in new brackets raised the question regarding the origin of cracks and it is the main subject of this paper. This paper also suggests a solution for avoidance of cracks on chain brackets.

Uprkos brojnim i skupim istraživanjima u oblasti zamora i loma kao i redovne kontrole gotovog proizvoda, prsline se javljaju svakodnevno u mnogim oblastima. Ovaj rad opisuje analizu otkaza spojnice lanca korišćene u konvejeru za transport cementa. Lančasti elevatori sa kašikom koriste spojnice za spajanje segmenata lanca i za vezivanje kašike za transport rasutog tereta. Površina kontakta između karike lanca i spojnice predstavlja jedno od najopterećenijih mesta na celom elevatoru. Tokom redovnog održavanja na upotrebljenim i novim spojnicama lanaca uočene su prsline u otvrdnutim termički obrađenim zonama. Radi povećanja otpornosti spojnica na habanje one se u oblasti kontakta sa karikom lanca termički obrađuju. Pojava prslina u novim nekorišćenim spojnicama pokrenula je ispitivanja sa ciljem da se utvrdi poreklo prslina na novim spojnicama. Pored ispitivanja uzroka nastanka ovih prslina u radu su navedeni predlozi mera za sprečavanje njihovog nastanka.