6860 KB230 KB0 KB2018Hriberšek, MatijaKopač, JanezPušavec, FranciXXVI, 118 str., 30 cmCOBISSID:16091419URN:URN:NBN:SI:doc-HMP89QMPslM. Hriberšekvisokošolska delacryogenic machiningcutting forcesDisertacijedissertationsInconel 718koeficient toplotne prestopnostikriogeno odrezavanjenumerical modelnumerični modelOdrezovanjeorthogonal cuttingortogonalno odrezavanjeresidual stressesrezalne silesurface heat transfer coefficientzaostale napetostiNapoved karakteristik obdelane površine pri kriogenem odrezavanju| doktorsko delo|Development in the field of machining process is based on the use of cooling lubrication fluids which are not harmful to people and environment, and on machining of high added-value products which usually consist of hard-machined materials. That is why cryogenic machining has developed, at which liquefied nitrogen can be used as a cooling lubrication fluid. The PhD thesis explains the design of a cryogenic cutting numerical model which has an ability to predict outputs of the cutting process (temperature, deformations, cutting forces etc.) and surface integrity (residual stresses) after cryogenic machining of Inconel 718. The FEM model in the first research consists of the definition of the values for the surface heat transfer coefficient in dependance to a boundary gaseous nitrogen layer temperature. The experimental results in the second part of the PhD thesis have shown that liquefied nitrogen contributes to better surface integrity because it has a great impact on removing the heat from the cutting zone. The measured cutting forces and residual stresses have validated the numerical model for cryogenic machining and consequently, the FEM model has become an useful tool for planning and optimizing cryogenic machining processRazvoj na področju odrezovalnih procesov temelji na uporabi hladilno-mazalnih sredstev, ki niso škodljiva za zdravje ljudi in okolje, ter obdelavi izdelkov z visoko dodano vrednostjo, ki so običajno iz težko obdelujočih materialov. Tako se je razvila tehnologija kriogenega odrezavanja, kjer je lahko eden izmed uporabljenih hladilnih medijev kapljeviti dušik. Doktorsko delo pojasnjuje zasnovo numeričnega modela za kriogeno odrezavanje, ki omogoča napoved odzivov rezalnega procesa (temperature, deformacije, rezalne sile itd.) in zaostalih napetosti pri kriogenem odrezavanju Inconela 718. Numerični model v prvi raziskavi zajema določitev vrednosti koeficienta toplotne prestopnosti v odvisnosti od temperature mejnega sloja, ki ga ustvari kapljeviti dušik na površini obdelovanca s pomočjo merjenja temperature v materialu. Eksperimentalni rezultati v drugi raziskavi so pokazali, da kapljeviti dušik prispeva k boljši integriteti površine po odrezavanju, saj ima sposobnost dobrega odvoda toplote iz rezalne cone. Izmerjene rezalne sile in zaostale napetosti so potrdile numerični model kriogenega odrezavanja, s čimer je model postal koristno orodje pri načrtovanju in optimizaciji kriogenega obdelovalnega procesaTEXTvisokošolska delatheses and dissertationsSlovenian National E-content AggregatorNational and University Library of SloveniaUniverza v Ljubljani, Fakulteta za strojništvo