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OPTIMIZACIJA RAZMESTITVE STROJEV V VALJARNI S POMOČJO GENETSKEGA ALGORITMA
Urban Rožej, 2011, diplomsko delo

Opis: Štore Steel d.o.o. je fleksibilna mini jeklarna, specializirana za dobavo jekel v manjših serijah. V letu 2010 je predviden zagon nove konti proge s tehnično letno kapaciteto 250.000 ton. Nova konti valjarska proga bo poleg povišane produktivnosti omogočala bistveno višji nivo kvalitete valjancev (tolerance, ravnost, površina, trdote), obenem pa s sodobnejšo avtomatizacijo tudi bistveno višji nivo zbiranja in prenosa informacij o izvršeni proizvodnji. Konfiguracija proge bo omogočala temeljitejšo on-line vzorčno kontrolo valjancev in posledično hitrejše ukrepanje, če bi prišlo do neskladnosti. Zgoraj navedene spremembe bodo bistveno vplivale tudi na bodoče izvajanje dodatnih opravil na valjancih (obrat adjustaže), obenem pa bo obstajala možnost premestitve strojev obrata adjustaže na nove lokacije. Cilj naloge je poiskati najprimernejšo razporeditev strojne opreme v obratu adjustaže in posledično transportnih poti glede na obstoječ proizvodni program in prostorske zmožnosti. Za reševanje problema razvrščanja strojev je bil uporabljen genetski algoritem, ki posnema evolucijo živih bitij. Dosežena je bila optimalna razmestitev strojev in s tem krajše transportne poti glede na dosedanje stanje.
Ključne besede: valjarna, optimizacija razmestitve strojev, optimizacija, evolucijsko računanje, genetski algoritmi;
Objavljeno: 11.03.2011; Ogledov: 2174; Prenosov: 166
.pdf Celotno besedilo (1,87 MB)

3.
ANALIZA VZROKOV ZA NOTRANJE NAPETOSTNE RAZPOKE
Marko Plank, 2011, diplomsko delo

Opis: Namen diplomske naloge je na podlagi kontrolnih in proizvodnih podatkov o izmetu, ultrazvo?ni kontroli, procesu valjanja ter kemijski sestavi, ugotoviti prevladujo? vzrok za nastanek napetostnih notranjih razpok. Opisan je tudi postopek ultrazvo?ne kontrole, s katerim se le-te ugotavljajo. Za napovedovanje nastanka notranjih napetostnih razpok smo uporabili metodo genetskega programiranja. Dobljeni model napove vse pojave notranjih napetostnih razpok. Rezultati naloge so bili prakti?no uporabni. Vzroki za nastanek napak so bili odpravljeni.
Ključne besede: valjanje, ohlajanje jekla, napetostne razpoke, ultrazvok, genetsko programiranje
Objavljeno: 31.05.2011; Ogledov: 1556; Prenosov: 191
.pdf Celotno besedilo (10,95 MB)

4.
Prenos profila DIN 1570 na novo linijo valjanja
Aljaž Zupanc, 2012, diplomsko delo

Opis: Podjetje Štore Steel se ukvarja z valjanjem jekla. Do sedaj se je jeklo valjalo na stari valjarski progi 550, sedaj se valjanje prestavlja na novo konti progo. Valjanje na konti progi je hitrejše, kvalitetnejše in bolj avtomatizirano, s tem pa tudi kompleksnejše in težje nadzorovano. Valjanje specialnih profilov z rebrom je zaradi nesimetrične oblike še zahtevnejše. Namen diplomskega dela je simulirati valjanje specialnega profila DIN 1570 na konti progi s programom Deform. Z računalniško simulacijo po metodi končnih elementov je določena sprememba oblike valjanca med valjanjem. Numerični rezultati so primerjani z dopustnimi odstopanji, ki so dani s standardom profila.
Ključne besede: Valjanje, Deform, specialni profil DIN 1570, konti proga, metoda končnih elementov
Objavljeno: 23.05.2012; Ogledov: 1189; Prenosov: 151
.pdf Celotno besedilo (8,83 MB)

5.
Intelligent programming of CNC turning operations using genetic algorithm
Jože Balič, Miha Kovačič, Boštjan Vaupotič, 2006, izvirni znanstveni članek

Opis: CAD/CAM systems are nowadays tightly connected to ensure that CAD data can be used for optimal tool path determination and generation of CNC programs for machine tools. The aim of our research is the design of a computer-aided, intelligent and genetic algorithm(GA) based programming system for CNC cutting tools selection, tool sequences planning and optimisation of cutting conditions. The first step is geometrical feature recognition and classification. On the basis of recognised features the module for GA-based determination of technological data determine cutting tools, cutting parameters (according to work piece material and cutting tool material) and detailed tool sequence planning. Material, which will be removed, is split into several cuts, each consisting of a number of basic tool movements. In thenext step, GA operations such as reproduction, crossover and mutation are applied. The process of GA-based optimisation runs in cycles in which new generations of individuals are created with increased average fitness of a population. During the evaluation of calculated results (generated NC programmes) several rules and constraints like rapid and cutting tool movement, collision, clamping and minimum machining time, which represent the fitness function, were taken into account. A case study was made for the turning operation of a rotational part. The results show that the GA-based programming has a higher efficiency. The total machining time was reduced by 16%. The demand for a high skilled worker on CAD/CAM systems and CNC machine tools was also reduced.
Ključne besede: CNC programming, genetic algorithm, intelligent CAM, turning, tool path generation
Objavljeno: 30.05.2012; Ogledov: 1267; Prenosov: 37
URL Povezava na celotno besedilo

6.
Intelligent interface in a flexible production environment
Igor Drstvenšek, Ivo Pahole, Miha Kovačič, Jože Balič, 2005, izvirni znanstveni članek

Opis: The paper describes a universal postprocessor initially intended to translate NC code for non-standard NC controllers. By adding arithmetic modules and connecting it to the technological database (TDB) it's functionality is broaden to a wider range of production planning problems, such as quick calculations of costs, evaluation of production possibilities and disposability of tools, etc. Thus, an automation tool is gained that enables its user to participate in a virtual manufacturing market and quickly and effectively evaluate jobs offered.
Ključne besede: production technology, virutal manufacturing, postprocessing, NC interface, CAM
Objavljeno: 01.06.2012; Ogledov: 836; Prenosov: 26
URL Povezava na celotno besedilo

7.
Prediction of maintenance of sinus rhythm after electrical cardioversion of atrial fibrillation by non-deterministic modelling
Petra Žohar, Miha Kovačič, Miran Brezočnik, Matej Podbregar, 2005, izvirni znanstveni članek

Opis: Atrial fibrillation (AF) is the most common rhythm disorder. Because of the high recurrence rate of AF after cardioversion and because of potential side effects of electrical cardioversion, it is clinically important to predict persistence of sinus rhythm after electrical cardioversion before it is attempted. The aim of our study was the development of a mathematical model by"genetic" programming (GP), a non-deterministic modelling technique, which would predict maintenance of sinus rhythm after electrical cardioversion of persistent AF. PATIENTS AND METHODS: Ninety-seven patients with persistent AF lasting more than 48 h, undergoing the first attempt at transthoracic cardioversion were included in this prospective study. Persistence of AF before the cardioversion attempt, amiodarone treatment, left atrial dimension,mean, standard deviation and approximate entropy of ECG R-R intervals were collected. The data of 53 patients were randomly selected from the database and used for GP modelling; the other 44 data sets were used for model testing. RESULTS: In 23 patients sinus rhythm persisted at 3 months. In the other 21 patients sinus rhythm was not achieved or its duration was less than 3 months. The model developed by GP failed to predict maintenance ofsinus rhythm at 3 months in one patient and in six patients falsely predicted maintenance of sinus rhythm. Positive and negative likelihood ratiosof the model for testing data were 4.32 and 0.05, respectively. Using this model 15 of 21 (71.4%) cardioversions not resulting in sinus rhythm at 3 months would have been avoided, whereas 22 of 23 (95.6%) cardioversions resulting in sinus rhythm at 3 months would have been administered. CONCLUSION: This model developed by GP, including clinical data, ECG data from the time-domain and nonlinear dynamics can predict maintenance of sinus rhythm. Further research is needed to explore its utility in the present or anexpanded form.
Ključne besede: optimisation methods, evolutionary optimisation methods, genetic algorithms, genetic programming, defibrillation, cardiac arrest prediction, atrial fibrillation, electrical cardioversion, prediction
Objavljeno: 01.06.2012; Ogledov: 1115; Prenosov: 18
URL Povezava na celotno besedilo

8.
Evolutionary programming of CNC machines
Miha Kovačič, Miran Brezočnik, Ivo Pahole, Jože Balič, Borut Kecelj, 2005, izvirni znanstveni članek

Opis: The paper proposes a new concept for programming of CNC machines. The concept based on genetic algorithms assures evolutionary generation and optimization of NC programs on the basis of CAD models of manufacturing environment. The structure, undergoing simulated evolution, is the population of NC programs. The NC programs control the machine which performs simple elementary motions. During the evolution the machine movement becomes more and more complex and intelligent solutions emerge gradually as a result of the interaction between machine movements and manufacturing environment. The examples of evolutionary programming of CNC lathe and CNC milling machine tool for different complexities of the blanks and products are presented. The proposed concept showed a high degree of universality, efficiency, and reliability and it can be also simply adopted to other CNC machines.
Ključne besede: manufacturing systems, NC-programming, CNC lathes, simulated evolution, genetic algorithms
Objavljeno: 01.06.2012; Ogledov: 845; Prenosov: 36
URL Povezava na celotno besedilo

9.
Evolutionary approach for cutting forces prediction in milling
Miha Kovačič, Jože Balič, Miran Brezočnik, 2004, izvirni znanstveni članek

Opis: Knowing cutting forces is important for choosing cutting parameters for milling. Traditionally, cutting forces are calculated by equation which includes empirically measured specific cutting forces. In the article modelling of cutting forces with genetic programming is proposed, which imitates principles of living beings. Measurements have been made for two materials (aluminium alloy AlMgSi1 and steel 1.2343) and two different types of milling (conventional milling and STEP milling). For each material and type of milling parameters, tensile strength and hardness of workpiece, tool diameter, cutting depth, spindle speed, feeding and type of milling were monitored, and for each combination of milling parameters cutting forces were measured. On the basis of the experimental data, different models for cutting forces prediction were obtained by genetic programming. Research shows that genetically developed models fit the experimental data.
Ključne besede: milling, simulation, milling cutting forces prediction, genetic programming
Objavljeno: 01.06.2012; Ogledov: 662; Prenosov: 24
URL Povezava na celotno besedilo

10.
Prediction of surface roughness with genetic programming
Miran Brezočnik, Miha Kovačič, Mirko Ficko, 2004, izvirni znanstveni članek

Opis: In this paper we propose genetic programming to predict surface roughness in end-milling. Two independent data sets were obtained on the basis of measurement: training data set and testing data set. Spindle speed, feed rate,depth of cut, and vibrations are used as independent input variables (parameters), while surface roughness as dependent output variable. On the basis of training data set, different models for surface roughness were developed by genetic programming. Accuracy of the best model was proved with the testing data. It was established that the surface roughness is most influenced by the feed rate, whereas the vibrations increase the prediction accuracy.
Ključne besede: end milling, surface roughness, prediction of surface roughness, genetic programming
Objavljeno: 01.06.2012; Ogledov: 871; Prenosov: 29
URL Povezava na celotno besedilo

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