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Softwarová podpora návrhu a hodnocení výměníků tepla se svazkem trubek v plášti / Software Aided Design and Assessment of Shell and Tube Heat ExchangersLétal, Tomáš Unknown Date (has links)
Subject of this work is a development of an integrated software environment for mechanical design and check of shell and tube heat exchangers. Processes of mechanical design and checks well as software which perform these processes are broken down to basic methods and parts. Mechanical design is usually performed according to some standards. In this work, ČSN EN 13445 is used. This standard describes mostly design check calculations which can be easily algorithmized. On the contrary, design calculations are described to some extent in few simple cases and mechanical design of shell and tube heat exchanger has not been fully algorithmized yet. Subject of this work is design of software, which will be capable of automatically performing mechanical design from datasheet as an input. Based on breakdown of design and check processes, requirements for key software features are derived. Important part of presented work is design and implementation of key modules – data model of shell and tube heat exchanger, module for mechanical design check according to ČSN EN 13445. These modules form basis of the software which will be developed further in future work.
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Robotic Illustration / Robotic Illustration : Illustration med industrirobotarWallin, Marcus January 2013 (has links)
Detta projekt åsyftade att möjliggöra för en industrirobot att illustrera godtyckliga digitalabilder på en plan yta. Detta uppnåddes genom att utrusta en manipulator med ett ritverktyg. Genom digital bildbehandling så kunde rörelsemönster genereras vilka matades till industriroboten för att den skulle kunna återskapa den digitala versionen. Roboten ritar med en teknik benämnd pointillism som innebär att endast punkter plottas. Resultatet blir en konkret svartvit representation av originalbilden. Projektet genomfördes på institutionen Industriell Produktion på Kungliga Tekniska Högskolan. Projektet är i sin natur väldigt inriktat på forskning och utveckling eftersom det går ut på skapandet av en teknik för att uppnå ett tydligt mål. Kontinuerlig utveckling var kopplat till målet för att förbättra resultatet från olika aspekter. / This project strived to enable an industrial robot to illustrate arbitrary digitized images on a planar surface. This was accomplished by equipping a robotic manipulator with a drawing utensil. Motion patterns were generated based on digital image processing and fed to the robot for it to imitate the digital version. The robot prints with a technique called pointillism, which implies that solely points are plotted. The result is a tangible black and white representation of the original image. The project was carried out in the Production Engineering facilities at the Royal Institute of Technology. The nature of the project is very research and development oriented as it deals with the creation of a technology to achieve an explicit goal. Continuous development was related to the goal to improve the result from different aspects.
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Amélioration de la partie supérieure du robot HYDROïD pour les tâches bi-manuelles et la manipulation / Improvement of the upper body of HYDROïD robot for bi-manual tasks and manipulationTayba, Ahmad 05 December 2017 (has links)
Ma thèse vise à contribuer au développement et l’amélioration de la cinématique de la partie supérieure du robot HYDROïD pour des tâches bi-manuelles, tout en basant sur une étude biomécanique de cette partie chez l’être humain.Pour atteindre notre objectif majeur, ce travail adopte dans un premier temps une nouvelle structure hybride de 4 degrés de liberté (ddl) pour le torse du robot, distribués en 3 ddl au niveau lombaire et un ddl au niveau thoracique. Cette structure était identifiée après une analyse de l’espace de travail d’un modèle multi-corps simulant la colonne vertébrale d’un être humain, et une étude d’optimisation de ce modèle permettant la synthèse de la structure envisagée.Dans un second temps, une amélioration de la cinématique du bras du robot a été mise en place, en introduisant la notion de l’épaule complexe au présente structure. Le choix de ce nouveau degré de liberté était le fruit d’une approche systématique pour augmenter l’anthropomorphisme géométrie du bras souhaité vers un bras humain de la même taille.Les 2 structures proposées ont passé par la suite par la phase de conception mécanique tout en respectant les contraintes géométriques et en se basant sur l’énergie hydraulique comme étant l’énergie d’ actionnement de ces systèmes. Enfin, le Modèle Géometrique Inverse (MGI) pour la solution générique du torse a été établi et son adaptation à notre cas particulier a été identifiée. Une solution optimisée pour ce mécanisme basée sur 2 différents critères a ensuite été donnée. / My thesis aims at contributing to the development and improvement of the upper body of HYDROïD robot for bi-manual tasks, while basing on a bio-mechanical study of this part of the human being. To reach our major goal, this work adopts, at first, a novel hybrid structure of 4 degrees of freedom (DOF) for the trunk of the robot, distributed in three DOF at the lumbar level and one DOF at the thoracic level. This structure was identified after an analysis of the work-space of a multi-body model feigning the vertebral column of a human being, and an optimization study of that model allowing the synthesis of the envisaged structure. Secondly, an improvement of the kinematics of the robor arm was organized, by introducing the notion of the shoulder complex in the present structure. The choice of this new degree of freedom was the fruit of a systematic approach to increase the anthropomorphism geometry of the arm wished towards a humanitarian arm of the same size.The two proposed structures crossed afterward by the mechanical design phase while respecting all the geometrical constraints and by using the hydraulic energy as being the type of actuation of these systems. Finally, the Inverse Geometrical Model (IGM) for the generic solution of the trunk was established and its adaptation to our particular case was identified. An optimized solution for this mechanism based on 2 various criteria was then given.
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Design and construction of a new solution for patios and glazing / Design och konstruktion av en ny lösning för uteplatser och inglasningarDahlén, Erik January 2022 (has links)
This thesis work has been conducted in collaboration with SPiNAB. The main assignment has been to create a new solution for adjustable windshields made of glass and keep low production costs. Throughout the project, the generic product development process has been followed with two main sources. A structure and a plan have been executed. A prestudy containing a benchmark with two competitors ''ClickitUp'' and ''Cit i Lä'' has been made. Needs have been collected and weighted. A detailed list of specifications has been made with missing data acquired from reverse engineering strategies. With the functional decomposition the functions ''Stabilize'' ''Adjust'' and ''Fit patio'' was used when generating ideas. The ideas were generated through brainstorming and research about similar solutions. After the elimination four concepts were left. The chosen concept ‘’The crutch’’ was constructed in detail with a mechanism that symmetrically disengages a cotter until released and fitted to the hole. Finally, weight calculations were made and a finite element analysis on the adjustable beam and the ground mount. The weight for the adjustable part is about 12 kg and the weight for the product as a whole is about 49 kg. The stress is 33.96 MPa and the displacement is 3.240 mm for the adjustable beam with a force of 510 N, representing 25 m/s of wind speed. The stress is 14.13 MPa and the displacement is 0.0297 mm for the ground mount for an impact force of 1 kN. The concept ''The crutch'' is the way to go forward. The concept needs some design changes before a physical prototype can be made. The weight of the adjustable part is deemed low enough to be lifted manually with the current mechanism. To keep the design cheap the beams and ground mount should have the possibility to be mirrored for the next section. / Detta examensarbete har utförts i samarbete med SPiNAB. Huvuduppdraget har varit att skapa en ny lösning för justerbara vindskydd av glas och hålla låga produktionskostnader. Under hela projektet har den generiska produktutvecklingsprocessen följts med två huvudkällor. En struktur och en plan har utförts. En förstudie som innehåller en benchmark med två konkurrenter ''ClickitUp'' och ''Cit i Lä'' har gjorts. Behoven har samlats in och viktats. En detaljerad kravspecifikation har skapats där saknad data har tagits fram med strategier för reverse engineering. Med funktionsnedbrytningen har funktionerna ''Stabilisera'' ''Justera'' och ''Passa uteplats'' använts för att generera idéer. Idéerna genererades genom brainstorming och studier av liknande lösningar. Efter eliminering återstod fyra koncept. Det valda konceptet ''Kryckan'' konstruerades i detalj med en mekanism som symmetriskt frigör en sprint tills den släpps och passar in i hålet. Slutligen gjordes viktberäkningar och en finita elementanalys av den justerbara balken och markfästet. Vikten för den justerbara delen är cirka 12 kg och vikten för produkten som helhet är cirka 49 kg. Spänningen är 33,96 MPa och förskjutningen 3,240 mm för den justerbara balken med en kraft på 510 N, vilket motsvarar en vindhastighet på 25 m/s. Spänningen är 14,13 MPa och förskjutningen 0,0297 mm för markfästet vid en slagkraft på 1 kN. Konceptet ''Kryckan'' är vägen framåt. Konceptet behöver några konstruktionsändringar innan en fysisk prototyp kan tillverkas. Vikten på den justerbara delen bedöms vara tillräckligt låg för att kunna lyftas manuellt med den nuvarande mekanismen. För att hålla konstruktionen billig bör balkarna och markfästet ha möjlighet att speglas för nästa sektion.
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Framtagning av ett chassi med upphängningssystem till en sexhjulig autonom leveransrobot / Development of a chassis with suspension system for a six-wheel autonomous delivery robotRacho, Afram January 2022 (has links)
En växande medvetenhet om miljöfrågor i kombination med den ökade produktiviteten och effektiviteten som skapas av automation och digitalisering har lett till ett växande intresse för autonoma leveransrobotar. TerraGo Deliveries utvecklar eldrivna autonoma leveransrobotar med fokus på matleveranser. Målet med detta arbete är att ta fram ett chassi med ett upphängningssystem för en sexhjulig autonom leveransrobot där upphängningssystemet gör det möjligt för roboten att klättra över hinder på en max höjd av 10 cm. Programmet Granta EduPack 2022 R1 har använts för att söka ett lämpligt tillverkningsmaterial. Aluminiumlegering 6061-T6 har valts på grund av dess goda egenskaper. Creo Parametric 7.0.6.0 har använts för att designa chassit och upphängningssystemet. Creo parametric har också använts för att utföra alla statiska finita elementanalyserna (FEA) och dynamiska mekanismanalyserna. Programmet Ultimaker Cura 4.12.1 med 3D-skrivaren Ultimaker 2+ har använts för att skapa en förminskad prototyp för lösningsförslaget. Resultatet har blivit ett stegramschassi med en bågformad boggi som upphängningssystem som gör att roboten kan klättra upp och ned hindren. / A growing awareness of environmental issues in combination with the increased productivity and efficiency created by automation and digitization has led to a growing interest in autonomous delivery robots. TerraGo Deliveries develops electrically powered autonomous delivery robots with a focus on food deliveries. The goal of this work is to develop a chassis with a suspension system for a six-wheeled autonomous delivery robot where the suspension system makes it possible for the robot to climb over obstacles at a maximum height of 10 cm. The Granta EduPack 2022 R1 software has been used to search for suitable manufacturing material. Aluminum alloy 6061-T6 has been chosen because of its good properties. Creo Parametric 7.0.6.0 has been used to design the chassis and suspension system. Creo parametric has also been used to perform all static finite element analyses (FEA) and dynamic mechanism analyses. The Ultimaker Cura 4.12.1 software with the Ultimaker 2+ 3D printer has been used to create a scaled-down prototype of the designed system. The result has become a ladder frame chassis with an arched bogie as a suspension system that enables the robot to climb up and down obstacles.
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Modeling and Analysis of Compliant Mechanisms for Designing NanopositionersShi, Hongliang January 2013 (has links)
No description available.
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Electromechanical Design and Development of the Virginia Tech Roller Rig Testing Facility for Wheel-rail Contact Mechanics and DynamicsHosseinipour, Milad 28 September 2016 (has links)
The electromechanical design and development of a sophisticated roller rig testing facility at the Railway Technologies Laboratory (RTL) of Virginia Polytechnic and State University (VT) is presented. The VT Roller Rig is intended for studying the complex dynamics and mechanics at the wheel-rail interface of railway vehicles in a controlled laboratory environment. Such measurements require excellent powering and driving architecture, high-performance motion control, accurate measurements, and relatively noise-free data acquisition systems. It is critical to accurately control the relative dynamics and positioning of rotating bodies to emulate field conditions. To measure the contact forces and moments, special care must be taken to ensure any noise, such as mechanical vibration, electrical crosstalk, and electromagnetic interference (EMI) are kept to a minimum. This document describes the steps towards design and development of all electromechanical subsystems of the VT Roller Rig, including the powertrain, power electronics, motion control systems, sensors, data acquisition units, safety and monitoring circuits, and general practices followed for satisfying the local and international codes of practice.
The VT Roller Rig is comprised of a wheel and a roller in a vertical configuration that simulate the single-wheel/rail interaction in one-fourth scale. The roller is five times larger than the scaled wheel to keep the contact patch distortion that is inevitable with a roller rig to a minimum. This setup is driven by two independent AC servo motors that control the velocity of the wheel and roller using state-of-the-art motion control technologies. Six linear actuators allow for adjusting the simulated load, wheel angle of attack, rail cant, and lateral position of the wheel on the rail. All motion controls are performed using digital servo drives, manufactured by Kollmorgen, VA, USA.
A number of sensors measure the contact patch parameters including force, torque, displacement, rotation, speed, acceleration, and contact patch geometry. A unified communication protocol between the actuators and sensors minimizes data conversion time, which allows for servo update rates of up to 48kHz. This provides an unmatched bandwidth for performing various dynamics, vibrations, and transient tests, as well as static steady-state conditions.
The VT Roller Rig has been debugged and commissioned successfully. The hardware and software components are tested both individually and within the system. The VT Roller Rig can control the creepage within 0.3RPM of the commanded value, while actively controlling the relative position of the rotating bodies with an unprecedented level of accuracy, no more than 16nm of the target location. The contact force measurement dynamometers can dynamically capture the contact forces to within 13.6N accuracy, for up to 10kN. The instantaneous torque in each driveline can be measured with better than 6.1Nm resolution. The VT Roller Rig Motion Programming Interface (MPI) is highly flexible for both programmers and non-programmers. All common motion control algorithms in the servo motion industry have been successfully implemented on the Rig. The VT Roller Rig MPI accepts third party motion algorithms in C, C++, and any .Net language. It successfully communicates with other design and analytics software such as Matlab, Simulink, and LabVIEW for performing custom-designed routines. It also provides the infrastructure for linking the Rig's hardware with commercial multibody dynamics software such as Simpack, NUCARS, and Vampire, which is a milestone for hardware-in-the-loop testing of railroad systems. / Ph. D.
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Ciência e tecnologia da manufatura de ultraprecisão de cerâmicas avançadas: Lapidorretificação Ud de superfícies planas de zircônia tetragonal policristalina estabilizada com ítria / Science and technology of ultra-precision manufacturing of advanced ceramics: Ud-lap grinding of flat surfaces of tetragonal zirconia policristal estabilized with itriaArthur Alves Fiocchi 12 September 2014 (has links)
O presente estudo aborda a fronteira da manufatura de ultraprecisão (UP) da zircônia tetragonal policristalina estabilizada com 3 mol% de ítria (3Y-TZP), realizado por meio da lapidorretificação Ud. A crescente demanda por produtos de cerâmicas avançadas com: elevado acabamento e integridade superficial; alta exatidão de forma; e menor custo de fabricação, tem fomentado pesquisas em diversas áreas da nanociência e nanotecnologia (N&N), visando sobrepujar as limitações ou agregando as principais vantagens dos tradicionais processos de retificação, lapidação e polimento. Em decorrência das excepcionais propriedades mecânicas, a cerâmica 3Y-TZP tem sido extensivamente aplicada na indústria. A 3Y-TZP, entretanto, pode apresentar a desestabilização da sua fase tetragonal em diferentes situações e condições, por exemplo, tendo início na própria manufatura, durante sua usinagem, podendo comprometer seu desempenho. Dessa forma, a 3Y-TZP pode ser considerada um material chave para avaliar e qualificar os processos abrasivos que visam padrão ouro de qualidade que, portanto, não devem suscitar a transformação martensítica. Em meio à pluralidade de processos, destaca-se a lapidorretificação Ud. A presente pesquisa estudou a manufatura UP de superfícies planas de zircônia TZ-3Y-E lapidorretificadas com rebolos de SiC de liga epóxi, almejando rugosidade nanométrica e integridade superficial sem danos microestruturais. Discos de TZ-3Y-E foram prensados isostaticamente a 200 MPa e sinterizados a 1400°C por 2 horas. Os discos foram caracterizados por meio de ensaios de: microdureza; perfilometria de contato e óptica; MEV-FEG; espectroscopia Raman; DRX; e microscopia confocal de epi-fluorescência. Os projetos mecânico e eletroeletrônico da Lapidorretificadora Fiocchi foram evoluídos na direção da retificação cerâmica UP. Os resultados demostraram que o projeto evolutivo da lapidorretificadora Fiocchi foi bem sucedido. A execução e controle das etapas de processamento cerâmico foram fundamentais para obter corpos cerâmicos densos e homogêneos, compatíveis com o acabamento aspirado. Os parâmetros de usinagem que se destacaram foram: profundidade de dressagem de 0,1 mm; pressão de lapidorretificação de 100 kPa; 100 rpm do rebolo e porta-peça; e emulsão (1:40) aplicada por MQF. A aspiração dos resíduos sobre o rebolo melhorou em 21,6% o acabamento, todavia a associação de abrasão dois (rebolo) e três corpos (abrasivos soltos) reduziu em 57,15% a rugosidade. O macroefeito foi visível nos rebolos de #800, #600 e #300 dressados com Ud = 1. A menor rugosidade, Ra = 60,63 nm, proveio do rebolo #300 dressado com Ud=5. O menor desvio de planeza, 0,308 μm, foi obtido com o rebolo de #800 e Ud = 3. O processo alcançou condições de plasticidade da zircônia que apontam para o predomínio dos mecanismos de remoção de microcorte e pulverização de material, sem ocorrência de microtrinca. Segundo ensaios de DRX e Espectroscopia Raman, a lapidorretificação Ud não provocou transformação martensítica. Todavia, o rebolo de #300 gerou alargamento assimétrico dos picos tetragonais nas proximidades de 2θ = 35° e 39° e a reversão das intensidades dos picos tetragonais a 40° e 41°. A reversão foi atribuída a mudança do domínio ferroelástico e a reorientação de planos cristalográficos em nível de cristalito. Os estudos sugerem que a usinagem introduziu tensão residual de compressão que pode ter estabilizado a fase romboédrica. Não há relato de processo capaz de alcançar acabamento nanométrico similar com mesmo tamanho e tipo de abrasivo. A lapidorretificação Ud pode substituir o engajamento da retificação, lapidação e polimento de cerâmica avançada. / The present study focuses on the border of ultra-precision (UP) manufacturing of 3 mol% yttria tetragonal zirconia polycrystal (3Y-TZP), carried out by Ud-lap grinding. The increasing demand for advanced ceramic products with: high surface finish and integrity; high form accuracy; and lower manufacturing cost, has encourage research in several areas of nanoscience and nanotechnology (N&N), to overcome the limitations or adding the main advantages of traditional grinding, lapping, and polishing processes. 3Y-TZP ceramics has been extensively applied by industry due to its exceptional mechanical properties. The 3Y-TZP, however, can present destabilization of its tetragonal phase in different situations and conditions. In the beginning of its manufacture, during its machining for instance, which may compromise its performance. Thus, the 3Y-TZP can be considered a key material to evaluate and qualify abrasive processes aiming gold standard quality that, therefore, should not raise the martensitic transformation. In the midst of plurality of processes, it is noteworthy the Ud-lap grinding. This research studied the UP manufacture of flat TZ-3Y-E zirconia surfaces lap ground with epoxy binder SiC grinding wheels, aiming to nanometer roughness and microstructural integrity without damage. Discs of TZ-3Y-E were isostatically pressed at 200 MPa and sintered at 1400 °C for 2 hours. The discs were characterized by tests of: microhardness; contact and optical profilometry; FEG-SEM; Raman spectroscopy; XRD; and confocal epi-fluorescence. Mechanical and electric-electronic designs of Fiocchi lap grinder were developed toward the UP ceramic grinding. Results showed that the developmental design of Fiocchi lap grinder was successful. The accomplishment and control of ceramic processing stages were essential for dense and homogenous ceramic bodies, compatible with the finish aspired. The machining parameters that stood out were: 0.1 mm depth of dressing; 100 kPa lap grinding pressure; 100 rpm grinding wheel and workpiece-holder; and emulsion applied by MQF. Suction of debris on the grinding wheel has improved finishing in 21.6%, however the combination of two-body abrasion (grinding wheel) and three-body abrasion (loose abrasives) decreased roughness in 57.15%. The macroeffect was visible on #800, #600, and #300 dressed with Ud = 1. The best finishing, Ra = 60.63 nm, came from #300 grinding wheel dressed with Ud = 5. The smallest flatness deviation, 0.308 μm, was obtained with the #800 grinding wheel and Ud = 3. The process has achieved zirconia plasticity conditions pointing towards predominance of microcutting and pulverization material removal mechanism without causing microcrack. According to XRD and Raman spectroscopy, the Ud-lap grinding caused no martensitic transformation. However, #300 grinding wheel has generated asymmetric broadening of the tetragonal peaks close to 2θ = 35° e 39° and reversal of the intensities of 40° and 41° tetragonal peaks. The reversal was attributed to ferroelastic switching and reorientation of crystallographic planes into crystallite level. Studies suggest that the machining has introduced compressive residual stress that may have stabilized rhombohedral phase. There is no report of an abrasive process capable of achieving similar nanometric finish with same grit size and type of abrasive. The Ud-lap grinding can replace the engagement of grinding, lapping, and polishing of advanced ceramics.
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Ciência e tecnologia da manufatura de ultraprecisão de cerâmicas avançadas: Lapidorretificação Ud de superfícies planas de zircônia tetragonal policristalina estabilizada com ítria / Science and technology of ultra-precision manufacturing of advanced ceramics: Ud-lap grinding of flat surfaces of tetragonal zirconia policristal estabilized with itriaFiocchi, Arthur Alves 12 September 2014 (has links)
O presente estudo aborda a fronteira da manufatura de ultraprecisão (UP) da zircônia tetragonal policristalina estabilizada com 3 mol% de ítria (3Y-TZP), realizado por meio da lapidorretificação Ud. A crescente demanda por produtos de cerâmicas avançadas com: elevado acabamento e integridade superficial; alta exatidão de forma; e menor custo de fabricação, tem fomentado pesquisas em diversas áreas da nanociência e nanotecnologia (N&N), visando sobrepujar as limitações ou agregando as principais vantagens dos tradicionais processos de retificação, lapidação e polimento. Em decorrência das excepcionais propriedades mecânicas, a cerâmica 3Y-TZP tem sido extensivamente aplicada na indústria. A 3Y-TZP, entretanto, pode apresentar a desestabilização da sua fase tetragonal em diferentes situações e condições, por exemplo, tendo início na própria manufatura, durante sua usinagem, podendo comprometer seu desempenho. Dessa forma, a 3Y-TZP pode ser considerada um material chave para avaliar e qualificar os processos abrasivos que visam padrão ouro de qualidade que, portanto, não devem suscitar a transformação martensítica. Em meio à pluralidade de processos, destaca-se a lapidorretificação Ud. A presente pesquisa estudou a manufatura UP de superfícies planas de zircônia TZ-3Y-E lapidorretificadas com rebolos de SiC de liga epóxi, almejando rugosidade nanométrica e integridade superficial sem danos microestruturais. Discos de TZ-3Y-E foram prensados isostaticamente a 200 MPa e sinterizados a 1400°C por 2 horas. Os discos foram caracterizados por meio de ensaios de: microdureza; perfilometria de contato e óptica; MEV-FEG; espectroscopia Raman; DRX; e microscopia confocal de epi-fluorescência. Os projetos mecânico e eletroeletrônico da Lapidorretificadora Fiocchi foram evoluídos na direção da retificação cerâmica UP. Os resultados demostraram que o projeto evolutivo da lapidorretificadora Fiocchi foi bem sucedido. A execução e controle das etapas de processamento cerâmico foram fundamentais para obter corpos cerâmicos densos e homogêneos, compatíveis com o acabamento aspirado. Os parâmetros de usinagem que se destacaram foram: profundidade de dressagem de 0,1 mm; pressão de lapidorretificação de 100 kPa; 100 rpm do rebolo e porta-peça; e emulsão (1:40) aplicada por MQF. A aspiração dos resíduos sobre o rebolo melhorou em 21,6% o acabamento, todavia a associação de abrasão dois (rebolo) e três corpos (abrasivos soltos) reduziu em 57,15% a rugosidade. O macroefeito foi visível nos rebolos de #800, #600 e #300 dressados com Ud = 1. A menor rugosidade, Ra = 60,63 nm, proveio do rebolo #300 dressado com Ud=5. O menor desvio de planeza, 0,308 μm, foi obtido com o rebolo de #800 e Ud = 3. O processo alcançou condições de plasticidade da zircônia que apontam para o predomínio dos mecanismos de remoção de microcorte e pulverização de material, sem ocorrência de microtrinca. Segundo ensaios de DRX e Espectroscopia Raman, a lapidorretificação Ud não provocou transformação martensítica. Todavia, o rebolo de #300 gerou alargamento assimétrico dos picos tetragonais nas proximidades de 2θ = 35° e 39° e a reversão das intensidades dos picos tetragonais a 40° e 41°. A reversão foi atribuída a mudança do domínio ferroelástico e a reorientação de planos cristalográficos em nível de cristalito. Os estudos sugerem que a usinagem introduziu tensão residual de compressão que pode ter estabilizado a fase romboédrica. Não há relato de processo capaz de alcançar acabamento nanométrico similar com mesmo tamanho e tipo de abrasivo. A lapidorretificação Ud pode substituir o engajamento da retificação, lapidação e polimento de cerâmica avançada. / The present study focuses on the border of ultra-precision (UP) manufacturing of 3 mol% yttria tetragonal zirconia polycrystal (3Y-TZP), carried out by Ud-lap grinding. The increasing demand for advanced ceramic products with: high surface finish and integrity; high form accuracy; and lower manufacturing cost, has encourage research in several areas of nanoscience and nanotechnology (N&N), to overcome the limitations or adding the main advantages of traditional grinding, lapping, and polishing processes. 3Y-TZP ceramics has been extensively applied by industry due to its exceptional mechanical properties. The 3Y-TZP, however, can present destabilization of its tetragonal phase in different situations and conditions. In the beginning of its manufacture, during its machining for instance, which may compromise its performance. Thus, the 3Y-TZP can be considered a key material to evaluate and qualify abrasive processes aiming gold standard quality that, therefore, should not raise the martensitic transformation. In the midst of plurality of processes, it is noteworthy the Ud-lap grinding. This research studied the UP manufacture of flat TZ-3Y-E zirconia surfaces lap ground with epoxy binder SiC grinding wheels, aiming to nanometer roughness and microstructural integrity without damage. Discs of TZ-3Y-E were isostatically pressed at 200 MPa and sintered at 1400 °C for 2 hours. The discs were characterized by tests of: microhardness; contact and optical profilometry; FEG-SEM; Raman spectroscopy; XRD; and confocal epi-fluorescence. Mechanical and electric-electronic designs of Fiocchi lap grinder were developed toward the UP ceramic grinding. Results showed that the developmental design of Fiocchi lap grinder was successful. The accomplishment and control of ceramic processing stages were essential for dense and homogenous ceramic bodies, compatible with the finish aspired. The machining parameters that stood out were: 0.1 mm depth of dressing; 100 kPa lap grinding pressure; 100 rpm grinding wheel and workpiece-holder; and emulsion applied by MQF. Suction of debris on the grinding wheel has improved finishing in 21.6%, however the combination of two-body abrasion (grinding wheel) and three-body abrasion (loose abrasives) decreased roughness in 57.15%. The macroeffect was visible on #800, #600, and #300 dressed with Ud = 1. The best finishing, Ra = 60.63 nm, came from #300 grinding wheel dressed with Ud = 5. The smallest flatness deviation, 0.308 μm, was obtained with the #800 grinding wheel and Ud = 3. The process has achieved zirconia plasticity conditions pointing towards predominance of microcutting and pulverization material removal mechanism without causing microcrack. According to XRD and Raman spectroscopy, the Ud-lap grinding caused no martensitic transformation. However, #300 grinding wheel has generated asymmetric broadening of the tetragonal peaks close to 2θ = 35° e 39° and reversal of the intensities of 40° and 41° tetragonal peaks. The reversal was attributed to ferroelastic switching and reorientation of crystallographic planes into crystallite level. Studies suggest that the machining has introduced compressive residual stress that may have stabilized rhombohedral phase. There is no report of an abrasive process capable of achieving similar nanometric finish with same grit size and type of abrasive. The Ud-lap grinding can replace the engagement of grinding, lapping, and polishing of advanced ceramics.
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Rechnerunterstützung des Entwurfsprozesses durch funktional-technische ObjektmodellierungZetzsche, Torsten 31 December 2000 (has links) (PDF)
Thema der Arbeit ist die Konzeption, Entwicklung und Einführung in die Anwendung eines Entwurfssystems, das die Leistungsfähigkeit der derzeit während des Entwurfsprozesses angewandten Programme durch neue Funktionen erweitert. Die implementierte integrative Schnittstellenlösung fasst die bisher genutzten Applikationen zu einem Gesamtsystem zusammen. Der bidirektionale Datenaustausch zwischen allen integrierten Modulen verhindert zur Zeit noch notwendige Mehrfacheingaben identischer Daten. Die für die Modellierung eingesetzten CAD-Systeme bieten für die rechnerinterne Abbildung der Geometrie von Bauteilen eine hohe Funktionalität. Ungenügend ist aber die Erstellung der Funktionsstruktur mit rechentechnischen Hilfsmitteln gelöst. Dieses führt zum Entwurf neuer Produkte nahezu ohne den Einsatz der Informationstechnik und zur anschließenden Anfertigung der CAD-Modelle und Zeichnungen, wenn die Bauteile bereits in ihrer Grundstruktur bestimmt sind. Auch die Vorteile der parametrischen 3D-Modellierung, die für die Beschreibung der bauteilinternen Abhängigkeiten anwendbar ist, werden nur begrenzt genutzt. Gründe dafür liegen in der komplizierten Definition eineindeutig bestimmter Modelle und im ungenügend gelösten Datenaustausch mit externen Applikationen. Während die Ergebnisse einer Konstruktion als rechnerinterne Geometriemodelle detailliert vorliegen, werden die Daten der zugrunde liegenden Funktionsstruktur nicht oder nur zum geringen Teil erfasst. Wichtige Informationen über den Entstehungsprozess sind somit nach Abschluss einer Konstruktion nicht mehr verfügbar. Aufgrund dessen muss die gleichwertige Modellierung von Funktions- und Wirkstruktur sowie der Geometrie realisiert werden. Mit dem beschriebenen Entwurfssystem werden diese Strukturen erstellt und in einem komplexen Modell gespeichert. Im Rahmen folgender Konstruktionen kann dann nicht nur auf die Geometriedaten, sondern auch auf die Beziehungen, auf denen die Bauteilstruktur basiert, zugegriffen werden.
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