Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2007. / Thesis presented in partial fulfilment of the requirements for the degree of Master of Engineering Science (Mechanical) at the University of Stellenbosch. / ENGLISH ABSTRACT: This thesis examines the development of a specialized, high-speed bearing in order to reduce vibration levels, reduce cutting times and increase blade stability during diamond sawing. The sawing process is required to be smooth, straight and unhindered – a task which is made difficult by the extreme hardness of the diamond as well as unseen grains which could potentially ruin the cut by deflecting the blade. This has an adverse effect on the quality of the cut and the yield obtained from the stone. The current equipment used for diamond sawing is very basic and a significant improvement can be made in terms of quality and sawing speed with the addition of an improved bearing. An aerostatic bearing was designed in order to achieve lower vibration levels and increased spindle speeds. A speed of 18 500 rpm was achieved with this bearing. A numerical model of the bearing was built with the aim of predicting the bearing’s dynamic behaviour. A finite element method (FEM) analysis was done to confirm the rigid body assumption made. Experimental modal analysis (EMA) was done to determine the frequencies and damping ratios of the natural modes of the rotor. The model was seen to predict the frequencies of the modes to within 6%. This model would be used for future design work to ensure that the frequencies of these modes are designed outside of the operating speed range of the aerostatic bearing. Tests were done to compare the vibration levels between the conventional machine and the aerostatic machine during sawing. The overall RMS acceleration was reduced by 70% on the housing of the aerostatic machine and by 50% on the diamond clamp. / AFRIKAANSE OPSOMMING: Hierdie tesis ondersoek die ontwikkeling van ‘n gespesialeerde, hoë-spoed laer om vibrasie en sny tye te verminder, asook om lem stabilitiet te verhoog in die diamant sny proses. Die sny proses moet glad, reguit en akkuraat wees, maar dit is nie altyd moontlik nie as gevolg van die variasie in hardheid van die diamant asook die naat in die daimant wat die lem maklik kan laat afwyk. Hierdie het ‘n negative effek op die kwalitiet van die snit. Die konvensionele diamant saag masjien is baie eenvoudig en ‘n groot verbetering in die snit kwalitiet en lemspoed is moontlik as ‘n nuwe laer ontwerp en implementeer kan word. ‘n Aerostatiese laer en rotor is ontwikkel om die vibrasie te verminder en die lemspoed to verhoog. ‘n Lemspoed van 18 500 rpm was verkry met die nuwe laer. ‘n Numeriese model is ontiwkkel om die beweging van die rotor dinamies te bereken. Die Eindige Element Metode (EEM) is gebruik om te bepaal of die aanname dat die rotor rigied is, wel aanvaarbaar is. Eksperimentele Modale Analise (EMA) is gebuik om die natuurlike frekwensies en die dempingsverhoudings vir die rotor te bepaal. Die model het die frekwensies tot binne 6% van die werklike waardes bereken. Hierdie model sal in die toekoms gebruik kan word vir die ontwerp van aerostatiese laers om te verseker dat die natuurlike frekwensies buite die spoedbereik van die aerostatiese masjien val. Toetse is gedoen om die vibrasievlakke van die huidige en die aerostatise masjien te meet tydens die snyproses. Die totale WGK versnelling het met 70% op die huls van die aerostatiese masjien, en met 50% op die diamant dop, verminder.

Diploma thesis is focused on cutting superhard materials (polycrystalline diamond and polycrystalline cubic boron nitride). It deals with physical, mechanical and cutting properties, production and effective use. Evaluative product range of superhard cutting materials of the prominent world producers in terms of cutting conditions and type of materials machined in turning.

In this Master’s Degree project the topic of handheld deep cutting is analysed. These days in the construction business workers face the challenge of cutting into concrete, brick and other mineralbased materials deeper than 15 cm. Currently there are a few handheld solutions for deep cutting but they have some major limitations, such as low reliability and safety, high price, maintenance and tiresome usage of these machines. In this paper the project is divided into two components – market research and concept development. To build a knowledge base, firstly, current technical platforms for handheld deep cutting machines are reviewed. Then, theoretical background behind market research and concept development is analysed. Following theoretical framework market research and concept development are implemented and steps taken described. Secondary research, customer interviews and focus groups are the main sources of information for the market research. Morphological and Pugh’s matrices are then used to generate and evaluate possible concepts, while software packages SolidWorks and KeyShot are used as tools for development of design features. Findings from the market research revealed that window, door, ventilation openings, resizing of bricks or concrete elements and fixing mistakes done during moulding are the main applications of deep cutting machines. It was noticed that most of the construction professionals are not aware of these machines, use workarounds or hire subcontractors. Single-phase electric ring saw is the outcome from product concepting stage. Three design features – toothed ring, telescopic blade guard and start switch – are then proposed. Finally, discussion of the whole project and its conclusions are given, recommendations and short overview on future work are provided. Work consists of 7 parts: introduction, frame of reference, implementation, results, discussion and conclusions, recommendations and future work, references. Thesis consists of: 68 pages of text without appendixes, 40 figures, 4 tables, 35 references. 8 appendixes attached. / I detta masterprojekt analyseras ämnet handhållen djupskärning. Nuförtiden inom byggbranchen står arbetarna inför utmaningen att skära i betong, tegel och annat mineralbaserat material som är djupare än 15 cm. För närvarande finns det ett antal handhållna lösningar för djupskärning, dock med stora begränsningar så som låg pålitlighet och säkerhet, högt pris och behov av underhåll samt tröttsam användning av dessa maskiner. I detta arbete delas projektet upp i två komponenter – marknadsundersökning och konceptutveckling. För att bygga upp en kunskapsbas granskas först nuvarande tekniska plattformar för handhållna djupskärningsmaskiner. Därefter analyseras teoretisk bakgrund om marknadsundersökning och konceptutveckling. Baserat på det teoretiska ramverket, implementeras marknadsundersökningar och konceptutveckling och genomförandet beskrivs. Sekundär forskning, kundintervjuer och fokusgrupper är de primära informationskällorna för marknadsundersökningen. Morfologiska och Pughs matriser används sedan för att generera och utvärdera möjliga koncept, medan programen SolidWorks och KeyShot används som verktyg för utveckling av designfunktioner. Resultat från marknadsundersökningen visade att fönster, dörrar, ventilationsöppningar, storlekändringar på tegelstenar eller betongelement och korrigering av defekter som uppkommit under gjutning är de huvudsakliga användningsområdena för djupskärningsmaskiner. Det noterades att de flesta byggnadsarbetarna inte är medvetna om dessa maskiner, använder improviserade lösningar eller anlitar underleverantörer. Enfasig elektrisk ringsåg är resultatet av produktkonceptionsstadiet. Tre designdetaljer – tandad ring, teleskopskärmskydd och startbrytare – föreslås därefter. Slutligen presenteras diskussion om projektet och dess slutsatser samt rekommendationer och en kort översikt över framtida arbete. Arbetet består av 7 delar: introduktion, referensram, genomförande, resultat, diskussion och slutsatser, rekommendationer och framtida arbete, referenser. Avhandlingen består av: 68 sidor text utan bilagor, 40 figurer, 4 tabeller, 35 referenser. 8 bilagor bifogade.

This master thesis work was aimed to enhance the designing of robots using cloud technologies. Analytical review of software to design robots, including PDM systems, was made. The specific features of such systems are presented and necessary modules are selected for designing the robot manipulator using CAD and PDM tools. 3D model of industrial robot was created using Semens NX CAD software. All the standards and regulatory documents related to the robotics design were considered. The design sequence of the robot manipulator with reference to standards (GOST 2.103-68 and GOST 19.102-77) is described. The project structure was created with use of Siemens Teamcenter PDM software and cloud technologies. / Данная магистерская диссертация направлена на внедрение технологий проектирования робототехнических систем в облаке. Спроектирован робот манипуляционного типа, создана электронная структура проекта в облаке с использованием программы PDM, проект размещен и организован для дальнейшего развития в облаке.

This master thesis work was aimed to enhance the computer aided modeling of cutting processes for hard brittle materials in optical and microelectronic industry. The parametric computer model of scribing the brittle wafer by diamond tool was developed using ANSYS APDL language and quasi-static conditions of treatment. Scribing of glass plates was realized by conic diamond tool on Roland CNC machine with different cutting parameters. Some experiments were made with coated glass plates. The surface quality of scribed plates was analyzed using AXIO ZEISS confocal microscope. The developed computer model enables predicting the defects zones in scribed brittle plate and searching the optimal cutting parameters and tool geometry. / Данная магистерская диссертация направлена на внедрение компьютерного моделирования технологических процессов резания применитльно к твердым хрупким материалам в оптической и электронной индустрии. Создана параметрическая компьютерная модель процесса скрайбирования алмазным инструментом для хрупкой пластины с использованием языка программирования ANSYS APDL в рамках квазистатического приближения. Скрайбирование стеклянныхз пластин было произведено коническим инструментом на станке с ЧПУ марки Roland с различными параметрами режима резания. Часть экспериментов проведена на пластинах с покрытием. Качество поверхности после скрайбирования было исследовано с помощью конфокального микроскопа AXIO ZEISS. Построенная компьютерная модель позволяет прогнозировать зону дефектности в скрайбированных хрупких пластинах и оптимизировать параметры режима резания, а также геометрию режущего инструмента.