20 research outputs found
Calculation of main drive of vertical machining center
Obradni centri predstavljaju osnovne jedinke (module) pri gradnji fleksibilnih obradnih sustava. Prigon glavnog gibanja obradnog centra treba udovoljiti visokim zahtjevima toÄnosti obradbe i krutosti zbog Äestih promjena optereÄenja i uÄestalosti vrtnje kod koriÅ”tenja razliÄitih vrsta reznih alata. Cilj je rada proraÄunati jedan takav prigon glavnog rotacijskog gibanja vertikalnog glodaÄeg obradnog centra. Nakon uvoda, u drugom poglavlju rada dan je prikaz obradnih centara, njihova podjela,osnovne znaÄajke te neke od moguÄih izvedbi. U treÄem poglavlju prikazane su najÄeÅ”Äe izvedbe glavnih prigona numeriÄki upravljanih alatnih strojeva. Äetvrto poglavlje daje smjernice projektiranja glavnog vretena i ostalih pripadajuÄih dijelova glavnog prigona alatnog stroja. SrediÅ”nji dio rada, peto poglavlje, Äini proraÄun, od izbora ulaznih parametara i izbora alata te režima obrade, preko izbora pogonskog elektromotora, proraÄuna remenskog prijenosa, dimenzioniranja glavnog vretena i izbora leÅ£ajeva do kontrole glavnog vretena, izbora drÅ£aÄa alata i sustava stezanja alata. U Å”estom poglavlju nalazi se dijagram toka proraÄuna prigona glavnog gibanja, a nakon toga zakljuÄak rada.CNC machining centres represent the primary individuals in the construction of flexible machining systems. Machining centres main driving mechanism must meet the high requirements for the processing accuracy and rigidity due to frequent load and speed changes upon using various types of cutting tools. The aim of this thesis is to calculate one such driving mechanism of the main rotational motion of a vertical milling machining centre. After the introduction, in the second chapter, CNC achining centres, their classification, main features and some possible implementations are presented. The third chapter discusses the most common designs of numerical controlled machining centres main driving mechanisms. The fourth chapter contains guidelines for the design of the main spindle and other associated parts of the machines main driving mechanism. The central part of this thesis, the fifth chapter, is the calculation, from input parameters, tool selection and processing modes, through drive motor selection, belt drive calculation, main spindle dimensioning, main spindle bearings definition to main spindle control, tool holder and tool clamping system selection. The sixth chapter contains a calculation flow diagram of the main driving mechanism. Thereafter is the conclusion
Influence of surface layer on mechanical and corrosion properties of nickel-titanium orthodontic wires
Objective: To analyze the effect of various coating formulations on the mechanical and corrosion properties of nickel-titanium (NiTi) orthodontic wires. Materials and Methods: Uncoated, rhodium-coated, and nitrified NiTi wires were observed with a three-point-bend test, surface roughness (Ra) measurement, scanning electron microscopy, energy dispersive spectroscopy, and electrochemical testing (open circuit potential, electrochemical impedance spectroscopy, and cyclic polarization scan). Differences in the properties of tested wire types were analyzed with analysis of variance and Tukey post hoc test. Results: Uncoated and nitrified NiTi wires showed similar mechanical and anticorrosive properties, while rhodium- coated NiTi wires showed the highest Ra and significantly higher modulus of elasticity, yield strength, and delivery of forces during loading but not in unloading. Rhodium-coated NiTi wires also had the highest corrosion current density and corrosion potential, lowest impedance modulus, and two time constants on Bode plot, one related to the Rh/Au coating and the other to underlying NiTi. Conclusion: Working properties of NiTi wires were unaffected by various coatings in unloading. Nitrification improved corrosion resistance. Rhodium coating reduced corrosion resistance and pronounced susceptibility to pitting corrosion in artificial saliva because of galvanic coupling between the noble coating and the base alloy
Developement of Nautical Tourism in Croatia and Europe in the Last Decade
NautiÄki turizam spada pod posebnu granu turizma koju turisti koriste u svrhu putovanja i razonode. PoÄeci nautiÄkog turizma sežu veÄ iz 16. stoljeÄa kada su se u Nizozemskoj odvijala yachting natjecanja po kanalima unutar države. Ovaj zavrÅ”ni rad bavi se analizom nautiÄkog turizma Atlantske, BaltiÄke i Mediteranske obale s posebnim osvrtom na Hrvatsku obalu. Najrazvijeniji nautiÄki turizam je na obali Mediterana zbog ugodne klime, razvijene obale i masovnog turizma. Po pitanju veÄe razvijenosti nautiÄkog turizma na Mediteranu istiÄe se Republika Hrvatska. Njezina razvedena obala i masovni turizam potiÄu razvoj i gradnju marina i luka te opÄenito nautiÄki turizam. U posljednjem desetljeÄu održivost dobiva veÄu važnost u svim granama turizma te se tako i u nautiÄkom turizmu uvodi poslovni model Plavog gospodarstva. Uz navedeno takoÄer se u radu analizira utjecaj pandemije COVID-a 19 koja je nastala 2020. godine te usporila ekonomiju država i time rezultirala smanjenjem opÄeg transporta ljudi, dobara i opÄenito turizma.Nautical tourism falls under a special branch of tourism that tourists use for the purpose of travel and leisure. The beginnings of nautical tourism date back to the 16th century when yachting competitions took place in the Netherlands on canals within the country. This final paper deals with the analysis of nautical tourism of the Atlantic, Baltic and Mediterranean coasts with special reference to the Croatian coast. The most developed nautical tourism is on the Mediterranean coast due to the pleasant climate, developed coast and mass tourism. In terms of greater development of nautical tourism in the Mediterranean, the Republic of Croatia stands out. Its indented coastline and mass tourism encourage the development and construction of marinas and ports and nautical tourism in general. In the last decade, sustainability has become more important in all branches of tourism, and thus the business model of the Blue Economy is being introduced in nautical tourism. In addition, the paper analyzes the impact of the COVID-19 pandemic that occurred in 2020 and slowed down the economy of the countries and thus resulted in a reduction in the general transport of people, goods and tourism in general
Calculation of main drive of vertical machining center
Obradni centri predstavljaju osnovne jedinke (module) pri gradnji fleksibilnih obradnih sustava. Prigon glavnog gibanja obradnog centra treba udovoljiti visokim zahtjevima toÄnosti obradbe i krutosti zbog Äestih promjena optereÄenja i uÄestalosti vrtnje kod koriÅ”tenja razliÄitih vrsta reznih alata. Cilj je rada proraÄunati jedan takav prigon glavnog rotacijskog gibanja vertikalnog glodaÄeg obradnog centra. Nakon uvoda, u drugom poglavlju rada dan je prikaz obradnih centara, njihova podjela,osnovne znaÄajke te neke od moguÄih izvedbi. U treÄem poglavlju prikazane su najÄeÅ”Äe izvedbe glavnih prigona numeriÄki upravljanih alatnih strojeva. Äetvrto poglavlje daje smjernice projektiranja glavnog vretena i ostalih pripadajuÄih dijelova glavnog prigona alatnog stroja. SrediÅ”nji dio rada, peto poglavlje, Äini proraÄun, od izbora ulaznih parametara i izbora alata te režima obrade, preko izbora pogonskog elektromotora, proraÄuna remenskog prijenosa, dimenzioniranja glavnog vretena i izbora leÅ£ajeva do kontrole glavnog vretena, izbora drÅ£aÄa alata i sustava stezanja alata. U Å”estom poglavlju nalazi se dijagram toka proraÄuna prigona glavnog gibanja, a nakon toga zakljuÄak rada.CNC machining centres represent the primary individuals in the construction of flexible machining systems. Machining centres main driving mechanism must meet the high requirements for the processing accuracy and rigidity due to frequent load and speed changes upon using various types of cutting tools. The aim of this thesis is to calculate one such driving mechanism of the main rotational motion of a vertical milling machining centre. After the introduction, in the second chapter, CNC achining centres, their classification, main features and some possible implementations are presented. The third chapter discusses the most common designs of numerical controlled machining centres main driving mechanisms. The fourth chapter contains guidelines for the design of the main spindle and other associated parts of the machines main driving mechanism. The central part of this thesis, the fifth chapter, is the calculation, from input parameters, tool selection and processing modes, through drive motor selection, belt drive calculation, main spindle dimensioning, main spindle bearings definition to main spindle control, tool holder and tool clamping system selection. The sixth chapter contains a calculation flow diagram of the main driving mechanism. Thereafter is the conclusion
Primjena āFour Step Modelaā na analizu kretanja osobnih automobila s moguÄom aplikacijom na energetsko planiranje punjenja elektriÄnih vozila ā sluÄaj grada Zagreba
Radi znatnijeg smanjenja emisija ugljiÄnog dioksida u transportnom sektoru Republike Hrvatske potrebno je zamijeniti konvencionalna goriva s obnovljivim izvorima energije. To je moguÄe napraviti primjenom elektriÄnih vozila te se sve viÅ”e pažnje posveÄuje na njihovu integraciju u transportne i energetske sustave. Cilj diplomskog rada je ispitati transportni sustav grada Zagreba s fokusom na putovanja osobnih vozila, kako bi se dobila satna krivulja optereÄenja transportnog sektora. Rad se temelji na metodi Four step model (FSM) za predviÄanje potreba za putovanjima te optereÄenje transportnog sustava. KoristeÄi analogiju s modelima predviÄanja prometnog optereÄenja FSM potrebno je razviti matematiÄki model primjene FSM u svrhe energetskog planiranja te napraviti procjenu krivulja optereÄenja u sektoru transporta u urbanim sredinama. FSM metoda dovela je do izraÄuna broja putovanja osobnih vozila pomoÄu kojih se dobila krivulja optereÄenja punjenja elektriÄnih vozila (EV). Svrha rada je ispitati utjecaj elektrifikacije transporta na krivulju potroÅ”nje elektriÄne energije u Zagrebu. ProraÄuni i ispitivanja provedena su za pet scenarija s razliÄitim postotkom penetracije elektriÄnih vozila. ProraÄunato je i optereÄenje sustava u H2RES-u te je prikazan utjecaj integracije elektriÄnih vozila na elektroenergetski sustav grada Zagreba. Analizom rezultata utvrdilo se da integracija EV negativno utjeÄe na elektroenergetski sustav Grada Zagreba te da neregulirano punjenje EV negativno utjeÄe na distribuciju krivulje potroÅ”nje. U radu su se analizirale i ukupne emisije CO2 proizvedene u Zagrebu iz osobnih vozila. Pokazano je da se poviÅ”enjem udjela elektriÄnih vozila smanjuju ukupne emisije CO2. S obzirom na referenti scenarij zabilježeno je smanjenje emisija CO2 od 34,7% u scenariju s penetracijom elektriÄnih vozila od 50%. Uz smanjenje emisija CO2 integracijom elektriÄnih vozila se ostvaruje smanjenje drugih Å”tetnih produkata izgaranja CO, \NO ,THC Äestice i buke
Calculation of main drive of vertical machining center
Obradni centri predstavljaju osnovne jedinke (module) pri gradnji fleksibilnih obradnih sustava. Prigon glavnog gibanja obradnog centra treba udovoljiti visokim zahtjevima toÄnosti obradbe i krutosti zbog Äestih promjena optereÄenja i uÄestalosti vrtnje kod koriÅ”tenja razliÄitih vrsta reznih alata. Cilj je rada proraÄunati jedan takav prigon glavnog rotacijskog gibanja vertikalnog glodaÄeg obradnog centra. Nakon uvoda, u drugom poglavlju rada dan je prikaz obradnih centara, njihova podjela,osnovne znaÄajke te neke od moguÄih izvedbi. U treÄem poglavlju prikazane su najÄeÅ”Äe izvedbe glavnih prigona numeriÄki upravljanih alatnih strojeva. Äetvrto poglavlje daje smjernice projektiranja glavnog vretena i ostalih pripadajuÄih dijelova glavnog prigona alatnog stroja. SrediÅ”nji dio rada, peto poglavlje, Äini proraÄun, od izbora ulaznih parametara i izbora alata te režima obrade, preko izbora pogonskog elektromotora, proraÄuna remenskog prijenosa, dimenzioniranja glavnog vretena i izbora leÅ£ajeva do kontrole glavnog vretena, izbora drÅ£aÄa alata i sustava stezanja alata. U Å”estom poglavlju nalazi se dijagram toka proraÄuna prigona glavnog gibanja, a nakon toga zakljuÄak rada.CNC machining centres represent the primary individuals in the construction of flexible machining systems. Machining centres main driving mechanism must meet the high requirements for the processing accuracy and rigidity due to frequent load and speed changes upon using various types of cutting tools. The aim of this thesis is to calculate one such driving mechanism of the main rotational motion of a vertical milling machining centre. After the introduction, in the second chapter, CNC achining centres, their classification, main features and some possible implementations are presented. The third chapter discusses the most common designs of numerical controlled machining centres main driving mechanisms. The fourth chapter contains guidelines for the design of the main spindle and other associated parts of the machines main driving mechanism. The central part of this thesis, the fifth chapter, is the calculation, from input parameters, tool selection and processing modes, through drive motor selection, belt drive calculation, main spindle dimensioning, main spindle bearings definition to main spindle control, tool holder and tool clamping system selection. The sixth chapter contains a calculation flow diagram of the main driving mechanism. Thereafter is the conclusion
STATE MATRIX
U ovom radu govorim o vrsti matiÄnih knjiga, njihovom nastanku, promjenama kroz povijest i samom voÄenju matiÄnih knjiga. Kroz samo pisanje ovoga rada i istraživanje spoznala sam Å”to su zapravo matiÄne knjige i svu njihovu vrijednost. MatiÄne knjige, u novije vrijeme znane kao državne matice su knjige putem kojih možemo na najlakÅ”i naÄin spoznati sve informacije koje nas zanimaju. PisajuÄi ovaj rad obogatila sam se novim saznanjima i vrijednostima koje su mi one dale.In this paper, I am talking about the type of birth books, their emergence, changes through history and the self-management of mother books. Through the writing of this paper and research I realized what the mother books are and what their value is all about. The mother-books, recently known as state nuts, are books through which we can easily understand all the information we are interested in. Writing this work I have enriched myself with the new knowledge and values that have given me