This thesis investigates minimal surfaces in design and researches their potential for constructability in concrete through the creation of physical prototypes with the design of two mold making processes, one being sacrificial and the other reusable. The study starts by acknowledging that minimal surfaces have been extensively explored in the field of differential geometry for decades. In spite of the availability of geometric definitions which provide the basic background for digital model generation (which in this text is assumed to be equal to design itself), minimal surfaces inspired very few people in their architectural design. This study attempts to look into the wider implications of minimal surfaces for architecture by taking up the challenge of designing and realizing various processes of mold making for the fabrication of such surfaces in concrete. Throughout this study, a gradient of complexity in the definition and digital modeling of minimal surfaces will be included as well as a variety of production methods in a research and fabrication based process, in order to investigate the correlation between what can be designed and what can be produced. I shall begin with a historical survey of the constructability of surfaces in thin shell concrete to provide background information for the reader. This chapter on the evolution of concrete structures presents a compilation of selected projects to illustrate the progress of thin shell construction throughout the history of architecture. It is here that I review what happened, why, and who made it possible. I draw heavily on published scholarly studies as most of the selected projects are cornerstones of the evolution of architecture and have been discussed by many others. Here, I simply attempt to remind the reader of the achievements of these projects in order to justify why investigation of the constructability of minimal surfaces may be the next step in the evolutionary process. After this section, the mathematics of surfaces in the complex plane is discussed based on information retrieved from many excellent resources. Here, the intention is to acquire information related to descriptions of various minimal surface types in differential geometry in order to be able to generate their representations in the digital environment. It would have been impossible to generate digital representations of minimal surfaces without the knowledge acquired through these descriptions. The last section provides a comparison of ruled surfaces and minimal surfaces meant to reveal the similarities and differences of such surfaces with regard to the principles of digital representation and fabrication. It provides insight into various fabrication techniques and materials to illuminate the design of a making process in which the goal is to know and control every parameter regarding both the design and fabrication of an object. The discussion of the design of a making process for a complexly shaped object provided in this part is followed by discussion of casting prototypes in concrete. In that section, the subject matter is the design and testing of various mold making techniques for the production of concrete prototypes of a selected minimal surface geometry. This section presents an increasing complexity of mold making from a sacrificial mold to a reusable mold.

Η παρούσα διπλωµατική εργασία πραγµατεύεται την κατασκευή µιας εργαλειοµηχανής µε αρθµητικό έλεγχο µέσω Η/Υ (CNC router) , ικανής για την κατασκευή ηλεκτρονικών πλακετών για τις ανάγκες του εργαστηρίου. Η εργασία αυτή εκπονήθηκε στο Εργαστήριο Ηλεκτροµηχανικής Μετατροπής Ενέργειας του Τµήµατος Ηλεκτρολόγων Μηχανικών και Τεχνολογίας Υπολογιστών της Πολυτεχνικής Σχολής του Πανεπιστηµίου Πατρών. Σκοπός είναι η κατασκευή της µηχανικής διάταξης της εργαλειοµηχανής µε επιφάνεια κατεργασίας πλακέτας µεγέθους τουλάχιστον Α4, των ηλεκτρονικών διατάξεων οδήγησης των κινητήρων, της διάταξης και της διασύνδεσης µε τον υπολογιστή, καθώς και των απαραίτητων προγραµµάτων για την ανάγνωση και επεξεργασία των σχεδίων και τη δηµιουργία και διαβίβαση των εντολών ελέγχου από και προς το µηχάνηµα ώστε να υλοποιηθεί το σχέδιο. Αρχικά έγινε η ανάλυση των απαιτήσεων του εργαστηρίου, επιλέχθηκε η συγκεκριµένη µέθοδος και αναλυθήκαν οι προδιαγραφές που πρέπει να έχει το µηχάνηµα. Έπειτα, έγινε η επιλογή της τοπολογίας και του υλικού του µηχανήµατος, των κατάλληλων κινητήρων, του συστήµατος ολίσθησης και του συστήµατος µετατροπής της κίνησης από περιστροφική σε γραµµική, έτσι ώστε να καλύπτονται µε το, χαµηλότερο δυνατό κόστος, οι απαιτήσεις µεγέθους, δύναµης πρόωσης, επιτάχυνσης, ανάλυσης, ακρίβειας, στιβαρότητας και ταχύτητας κίνησης που αναλύθηκαν στο πρώτο στάδιο, µε το χαµηλότερο δυνατό κόστος. Στη συνέχεια σχεδιάστηκε σε πρόγραµµα τρισδιάστατου σχεδιασµού η µηχανική κατασκευή της διάταξης και ανατέθηκε σε κατάλληλο εργαστήριο η κατασκευή των κοµµατιών και η συναρµολόγηση της. Το επόµενο βήµα ήτανε να σχεδιαστούν και να κατασκευαστούν τα κυκλώµατα για την οδήγηση των κινητήρων και η κεντρική πλακέτα που αναλαµβάνει την οµαλή διασύνδεση τους µε τον υπολογιστή. Τέλος, γράφτηκαν κατάλληλα προγράµµατα τα οποία αναλαµβάνουν την ανάγνωση του σχεδίου της πλακέτας και παράγουν και διαβιβάζουν τις κατάλληλες εντολές στους οδηγούς των κινητήρων, ώστε να γίνουνε οι απαραίτητες κινήσεις από αυτούς και να υλοποιηθεί το σχέδιο στην πλακέτα. / This thesis is about designing and building a fully functional CNC machine, capable of building printed circuit boards.

Η παρούσα διπλωματική εργασία πραγματεύεται την μελέτη και την κατασκεύη μιας αυτοματοποιημένης διάταξης επίστρωσης ηλεκτροδίου σε στερεό ηλεκτρολύτη για εφαρμογή σε κυψέλες καυσίμου.Η εργασία εκπονήθηκε στο Εργαστήριο Ηλεκτρομηχανικής Μετατροπής Ενέργειας του Τμήματος Ηλεκτρολόγων Μηχανικών και Τεχνολογίας Υπολογιστών της Πολυτεχνικής Σχολής του Πανεπιστημίου Πατρών. Σε αυτό το πλαίσιο,σχεδιάστηκε μια εργαλειομηχανή τύπου CNC(Computer Numerical Control),υψηλής ακρίβειας,ικανή να εκτελέσει κινήσεις σε τρείς άξονες,ελεγχόμενη από μικροελεγκτή και οδηγούμενη από βηματικούς κινητήρες. Αν και ο απώτερος στόχος της εργασίας είναι η κατασκευή της διάταξης που επιτελεί το επιθυμητό έργο,προηγήθηκε εκτενής θεωρητική μελέτη και ανάλυση όλων των χαρακτηριστικών και παραγόντων του συστήματος. Αρχικά,γίνεται αναφορά στις κυψέλες καυσίμου,στους διάφορους τύπους της συγκεκριμένης τεχνολογίας καθώς και στις εφαρμογές που αυτή ενσωματώνεται. Οι κυψέλες καυσίμου,ως αντικείμενο επιστημονικής μελέτης αλλά και ως εμπορευματικό προϊόν παρουσιάζει εξαιρετικό ενδιαφέρον και έχει απασχολήσει σε μεγάλο βαθμό την επιστημονική κοινότητα τα τελευταία χρόνια λόγω της μεγάλης αποδοτικότητάς τους στην παραγωγή ενέργειας αλλά και της φιλικής προς το περιβάλλον λειτουργίας τους. Εν συνεχεία,αναλύεται ο όρος αριθμητικός έλεγχος και αναλύονται οι εφαρμογές στις οποίες αυτός χρησιμοποιείται ενώ παράλληλα γίνεται αναφορά στο μηχανολογικό τμήμα της κατασκευής,στα υλικά και στο σχεδιασμό τέτοιων διατάξεων. Σημαντικό μέρος της εργασίας αφιερώθηκε στους βηματικούς κινητήρες που επελέχθησαν ως κινητήρες προώσεως της εργαλειομηχανής.Αναλύονται τόσο οι τύποι βηματικών κινητήρων όσο και ο έλεγχος τους ενώ ακόμα παρουσιάζεται και η στατική αλλά και η δυναμική τους συμπεριφορά σε ένα σύστημα. Τον ‘’εγκέφαλο’’ της διάταξης αποτελεί ο μικροεπεξεργαστής που ενσωματώνει το πρόγραμμα λειτουργίας της εργαλειομηχανής,ο οποίος αναλύεται σε μεγάλο βαθμό ξεκινώντας από τον ορισμό του,τη φύση της λειτουργίας του και καταλήγωντας στον ειδικότερο ρόλο που διαδραματίζει στο κύκλωμα ελέγχου της διάταξης. Ακόμα, περιγράφεται η αρχή λειτουργίας και η κατασκευαστική λογική της πλακέτας ελέγχου και οδήγησης του συστήματος.Τα συμπεράσματα της εργασίας και οι μελλοντικές επεκτάσεις που πιθανώς η διάταξη επιδέχεται παρουσιάζονται ως επίλογος. / The purpose of this thesis is the construction of an automated device that coats electrodes in to solid electrolyte for application in fuel cells. The project was conducted in Electromechanical Energy Conversion Laboratory, at Department of Electrical and Computer Engineering of the University of Patras. In this context, a CNC (Computerized Numerical Control) machine, capable of carrying out movements in three axes, controlled by stepper motors was designed. Although the ultimate purpose is the construction of such a device, an extensive theoretical study and analysis of all parameters and characteristics of the system was preceded. Initially, a reference to fuel cells is being made, describing the different types of the technology and the applications which fuel cells are incorporated. In general, fuel cell technology as an object of theoretical study and as a commodity product as well, is considered to be of high scientific interest, due to its high efficiency and it’s environmental friendly operation. In addition, a general definition of numerical control is being given relatively to its applications, providing a special interest in the mechanical design of systems that incorporate this particular method of control. A significant part of the project was consumed by the analysis of stepper motor behavior, both static and dynamic. Different types of stepper motors are being described along with several types of control schemes. Extensive description of the system’s incorporated micro-controller has been made, from its general description down to its specialized role to the system. Finally, the basic principles of operation are being described, given a special interest in to the board of control and drive of the system. The evaluation of the project’s status as well it’s future development were given as final conclusions.

A tool path generation method for sculptured surfaces defined by triangular meshes is presented in this thesis along with an algorithm that helps determine the best type of cutter geometry to machine a specific surface. Existing tool path planning methods for sculptured surfaces defined by triangular meshes require extensive computer processing power and result in long processing times mainly since surface topology for triangular meshes is not provided. The method presented in this thesis avoids this problem by offsetting each triangular facet individually. The combination of all the individual offsets make up a cutter location surface. A single triangle offsetting results in many more triangles; many of these are redundant, increasing the time required for data handling in subsequent steps. To avoid the large number of triangles, the proposed method creates a bounding space to which the offset surface is limited. The original surface mesh describes the bounding surface of a solid, thus it is continuous with no gaps. Therefore, the resulting bounding spaces are also continuous and without gaps. Applying the boundary space limits the size of the offset surface resulting in a reduction in the number of triangular surfaces generated. The offset surface generation may result in unwanted intersecting triangles. The tool path planning strategy addresses this issue by applying hidden-surface removal algorithms. The cutter locations from the offset surface are obtained using the depth buffer. The simulation and machining results show that the tool paths generated by this process are correct. Furthermore, the time required to generate tool paths is less than the time required by other methods. The second part of this thesis presents a method for selecting an optimal cutter type. Extensive research has been carried out to determine the best cutter size for a given machining operation. However, cutter type selection has not been studied in-depth. This work presents a method for selecting the best cutter type based on the amount of material removed. By comparing the amount of material removed by two cutters at a given cutter location the best cutter can be selected. The results show that the optimal cutter is highly dependent on the surface geometry. For most complex surfaces it was found that a combination of cutters provides the best results.

Current survey has showed that people with disability need equal work opportunity. Meanwhile, labor shortage is becoming more and more serious in existing manufacturing industry and there is less physical work involved in CNC machine operation. Thus it is a good opportunity for people with disability to work in manufacturing industry as CNC operators. In the preliminary research, observation, interview and domain research were conducted to understand activates of FVMC (Fadal Vertical Machining Center is a type of CNC machine) operators. Researchers found the existing FVMC are very inconvenient to use, because most of them were designed for the general public. Operator's performance was restricted by the poor design of the machines and the work area. As a result, many people, especially wheel chair users have found limited employment opportunities in the manufacturing industry. To address this problem, on one hand, we presented a study on the current FVMC. A Full size FVMC was mocked up and 9 wheelchair users and 6 able-body users participated in this study. They were asked to mimic to finish the tasks relate to FVMC operation. This study also aims at collecting data for universal FVMC design. On the other hand, based on the preliminary research two concept of FVMC design scenarios are also developed and evaluated by two groups of subjects. This study addressed limitations of wheelchair users with respect to CNC operation, especially reaching issues, and collected data about the preferred FVMC settings and design from wheelchair users and able-bodied people. At the end, design guidelines were developed for machine engineers or designers in two aspects: 1) improve currently available FVMC; 2) redesign FVMC that is safer and easier to use. These guidelines will increase the potential of employing wheelchair users alongside able-bodied people in the manufacturing industry.

Thesis (doctoral)--Techn. Universiẗat, Darmstadt, 2003.

Zugl.: Darmstadt, Techn. Univ., Diss., 2009

Orientador: Ruis Camargo Tokimatsu / Resumo: A sociedade sempre busca inovações como facilitadores de processos para o alcance de objetivos propostos em distintas áreas, utilizando instrumentos, métodos e técnicas diversas. Dentre estas encontra-se a Engenharia Reversa (ER), que é o processo de engenharia afim de se obter um produto ou objeto a partir de um modelo original. Nos últimos anos, com a rápida evolução tecnológica , envolvendo máquinas, ferramentas e softwares, a ER passou a ser um recurso utilizado até mesmo por pequenas e médias empresas. O proposito desta pesquisa é avaliar o desempenho da aplicação de recursos de engenharia, tais como hardwares e softwares de baixo custo ou de uso livre, sobre a ER a fim de obter-se uma peça usinada em uma maquina CNC o mais fiel possível ao modelo físico original. Para isso foram aplicados os conceitos, os processos e recursos necessários nas etapas de reconstrução de um modelo físico , desde a digitalização 3D, utilizando scanners tridimensionais, o tratamento do objeto capturado, a reconstrução do modelo no software CAD até a geração do código G, por meio de softwares CAM, a ser enviado a uma máquina CNC para realização da usinagem e obtenção da peça modelo. Foi utilizado o scanner 3d manual Ciclop, cuja digitalização resultou em dimensões muitas próximas ao objeto original. Também foram utilizados os softwares Meshlab para tratamento do modelo digitalizado e o AutoCad Fusion 3D para criação do modelo CAD e geração dos processos de usinagem e código G, escolhidos devid... (Resumo completo, clicar acesso eletrônico abaixo) / Mestre

No estado do Rio Grande do Sul, os garimpos de pedras preciosas estão distribuídos em duas regiões principais: no Distrito Mineiro de Ametista do Sul (maior produtor de ametista) e no Distrito Mineiro de Salto do Jacuí (maior produtor de ágata). Nestes dois distritos mineiros são explorados geodos, parcial ou totalmente preenchidos por camadas intercaladas de ágata, quartzo incolor, ametista, calcita e opala. O processo de extração desses geodos gera grande quantidade de rejeito, composto tanto pela rocha portadora do minério como também por minério de baixa qualidade. No município de Soledade se concentram as principais empresas de beneficiamento e também o comércio dos materiais gemológicos explorados no Rio Grande do Sul. No entanto, a maioria dos objetos produzidos que visam à exportação se repete nas diversas indústrias beneficiadoras sem diferencial aparente. A opala encontrada nos garimpos de Salto do Jacuí ocorre em muitas cores. A opala branca é a mais comum e não é valorizada, gerando, assim, significativa quantidade de rejeito. Através deste estudo, objetiva-se estabelecer uma metodologia de beneficiamento por usinagem CNC do rejeito de opala branca e ágata oriundo do Distrito Mineiro de Salto do Jacuí, que agregue valor pelo design e tecnologia. Considerando que os processos mais utilizados nas indústrias atualmente para a ágata, o tingimento e o corte em chapas, não se aplicam à opala, pode-se afirmar que a introdução da tecnologia de usinagem CNC neste setor pode auxiliar no aproveitamento desse material, ao modificá-los e valorizá-los como objetos de adorno sob a forma de camafeus. A metodologia empregada para a presente pesquisa consistiu de etapas de identificação dos locais de extração de ágata e de opala branca do Estado; avaliação dos procedimentos mais utilizados para beneficiamento destes materiais; estudo e análise do material por técnicas específicas; ensaios de usinagem CNC, análise das fresas utilizadas e dos materiais envolvidos após os processos de usinagem e desenvolvimento de produto. Foram realizados nove ensaios de usinagem e as análises posteriores, identificando nos resultados obtidos que, com as fresas adequadas destinadas ao desgaste (maior diâmetro) ou acabamento (menor diâmetro de ponta), quando utilizados em conjunto com parâmetros e estratégias de usinagem bem definidos, são suficientes para que se alcance o objetivo definido nesta pesquisa. / In the state of Rio Grande do Sul, the precious stones mines are distributed in two main regions: in the Mining District of South Amethyst (largest producer of amethyst) and the Mining District of the Salto Jacuí (largest producer of agate). In these two districts Geodis miners are exploited, partially or completely filled by intercalated layers of agate, clear quartz, amethyst, opal and calcite. The extraction process of Geodis generates large amounts of waste, comprising both the rock of the ore carrier as well as of low quality ore. In the municipality of Soledade focus the main company to benefit from trade and gemological materials used in Rio Grande do Sul. However, most of the objects produced aimed at the export is repeated in various industries benefit without apparent difference. The opal found in the mines of the Salto Jacuí appears in many colors. The white opal is the most common and is not valued, thus generating significant amount of waste. Through this study, that aims to establish a methodology for processing by the CNC machining waste of opal and white agate from the Mining District of the Salto Jacuí, a great value was added for design and technology. Whereas the most currently used in industries for agate, dyeing and cut into plates, are not applied to the opal, one can say that the introduction of CNC machining in this sector can assist in the exploitation of such material, to modify and value them as objects of adornment in the form of camafeus. The methodology used for this research consisted of steps of identifying locations for extraction of opal and white agate the state, evaluate the procedures used for further processing of these materials, study and analysis of the material by specific techniques, testing of CNC machining, analysis of cutters and materials used after the processes involved in machining and product development. Were conducted nine tests of machining and the subsequent analysis, identifying the results that, with the cutters suitable for the wear (larger diameter) or finishing (minor diameter of tip), when used together with parameters and machining strategies for well-defined, are sufficient to achieve the goal defined in this study.

This thesis was conducted to provide an automated method for characterization of printed electronics. The work was built on a multi-axis milling machine. Further, the machine was modified by replacing the milling-tool with an installment utilizing electrical probing. Different measurement techniques, machine vision applications, and software solutions were evaluated and utilized. All the revolving functionalities of this project was then merged into a complete system, controlled by a graphical user interface. The resulting system was capable of autonomously characterize a given number of components on a printed sheet. The final version of the system is capable of finding the origin of the sheet by using machine vision and fiducial markers.