Bimetallic cast iron rolls – Some approaches to assure the exploitation properties

Abstract

U ovom se radu detaljno razmatra utjecaj nekih tehnoloških faktora na trajnost valjaoničkih željeznih valjaka i predlažu rješenja za povećanje izdržljivosti u uporabi. Istraživanjem se pokušavaju dati odgovori na najvažnije probleme u vezi povećanja tvrdoće valjaka. Dobiveni rezultati su od neposredne praktične koristi kako za proizvođačku industriju valjaoničkih valjaka od lijevanog željeza tako i za valjaoničke odjele. U tom se smislu ovi rezultati mogu koristiti u ljevaonicama i valjaonicama za osiguranje kvalitete valjaka sve od faze proizvodnje pa do uporabe, što neizbježno vodi do osiguranja kvalitete proizvedenih laminata. Analiziraju se stvarni tehnički uvjeti lijevanja kako bi se povećala otpornost valjaka na trošenje, smanjili troškovi konverzije i reducirao otpad, smanjili radni troškovi smanjivanjem bogato legiranog željeza s potrošnjom nikla, kroma i molibdena. Korištenjem nove metode istraživanja – numeričke simulacije – obradili su se statistički i matematički podaci zabilježeni kada se elaborirao željezni lijev tipa FDId2 namijenjen lijevanju tvrde kore bimetalnih valjaka velikog promjera. Svrha je optimizirati kemijski sastav kao faktor od utjecaja na tvrdoću valjaka, a tako implicitno i na njihova uporabna svojstva. Postizanje optimalnog kemijskog sastava može predstavljati tehnički efikasan način za osiguranje uporabnih svojstava budući da materijal valjaka ima u tom smislu važnu ulogu. Primijenjena je matematička metoda počevši od diferenciranja sastavnih dijelova valjaka, uzimajući u obzir industrijske podatke dobivene u ljevaonici valjaka, kao i specifikacije nacionalnog standarda koji preporučuje tvrdoću kod različitih kemijskih sastava. U tom smislu ovo istraživanje može pridonijeti optimiziranju industrijskih tehnologija analizom i matematičkim eksperimentom.The study represents a detailed approach of the influence of some technological factors on durability in exploitation of rolling mill iron rolls and suggests solutions meant to increase the durability of the rolls in exploitation. These researches are trying to give answers to most of the actual problems related to the increase of hardness of rolling mill rolls. These results are of immediate practical utility both for the cast-iron rolling mills roll manufacturing industry and the rolling sectors. In this sense, these research results can be used in the collective framework of the foundries and the rolling mills sectors for quality assurance of rolls as far back as the phase of production to their exploitation, what leads to, inevitably, the quality assurance of produced laminates. Genuine casting technical conditions are analyzed in order to increase the rolls\u27 resistance to wearing, decrease the conversion costs and reduce the waste, decrease the labor costs by lowering the richly alloyed iron with nickel, chromium and molybdenum consumption. Using the new research technique – the numerical simulation – statistical and mathematical data, registered when elaborating the cast iron type FDId2 destined to cast the hard crust of the large-diameter bimetallic rolls, were processed within the present research. The purpose is the optimization of the chemical composition as an influential factor on the rolls hardness, thus, implicitly, on their exploiting qualities. The realization of an optimal chemical composition can constitute a technically efficient mode to assure the exploitation properties, the rolling mills rolls material having an important role in this sense. From this point of view the mathematical modeling is applied, starting from the differentiation on rolls component parts, taking into consideration the industrial data obtained in rolls-foundry, as well as the national standard specifications, which recommend the hardness for different chemical compositions. From this point of view the research is inscribed in the context of scientific capitalization of the process and the industrial technologies optimization, in the way of the analysis and the mathematical experiment