Orientador: Amauri Hassui / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-21T02:13:50Z (GMT). No. of bitstreams: 1 Castro_MarceloHirai_M.pdf: 4008200 bytes, checksum: a0c71450e4b5c3ac934e22f6e3cc9f4b (MD5) Previous issue date: 2012 / Resumo: A inovação é a chave para o diferencial da indústria no mercado competitivo atual. Fazer diferente, melhor e mais barato sempre agrega valor ao produto. Por outro lado, a resistência às mudanças faz parte do comportamento humano, seja na sociedade, ou na indústria. O objetivo principal deste trabalho é estudar a viabilidade de se fazer furos não cilíndricos com uma ferramenta em rotação utilizando máquinas-ferramenta CNC. Estes sempre foram obstáculos na indústria de fabricação pela dificuldade de obtenção. Sendo assim, o processo apresentado nesse trabalho busca usinar um furo quadrado com a mesma configuração de ferramentas e fixação de peças utilizadas para um furo cilíndrico, tão comum à indústria. Isso visa reduzir custos de fabricação e facilitar a obtenção de furos não cilíndricos com os recursos de equipamentos programáveis existentes no chão de fábrica. A partir de um modelo matemático, a máquina é programada para executar movimentos sincronizados entre a rotação e os deslocamentos do eixo da ferramenta. Diversas programações foram testadas em diferentes máquinas ferramenta CNC, com diferentes comandos, com e sem recursos de alta velocidade, com diferentes quantidades de pontos programados, interpolações lineares e circulares. A partir dos experimentos, foram analisadas as configurações das máquinas, a capacidade de execução do controlador numérico instalado, a velocidade desenvolvida pela máquina na operação e a geometria obtida dos furos quadrados. Os experimentos apontam que para executar o furo quadrado, os comandos devem ser capazes de controlar um eixo rotativo como eixo propriamente dito, além de sincronizarem mais três eixos lineares. O crítico para este tipo de operação é a velocidade desempenhada pela máquina, sendo o fator mais significativo, o tempo que o comando precisa para o processamento do bloco de programação, independentemente da ativação de recursos de alta velocidade, interpolações lineares ou circulares. Verificou-se também que quanto maior a quantidade de pontos para compor a trajetória do centro da ferramenta, melhor será a geometria obtida do furo. Sendo assim, as máquinas ferramenta CNC que estão em operação na indústria são capazes de realizar a furação não cilíndrica de forma muito próxima à furação cilíndrica quanto ao tempo de usinagem e ao sistema de fixação da ferramenta e da peça, sendo necessária uma programação sincronizada do eixo spindle presente em toda e qualquer máquina ferramenta / Abstract: The innovation is the key for the differential of the industry on the competitive market nowadays. To make different, better and cheaper always it is worth a lot to the product. By the other side, the resistance to changes makes part of the human behavior, in society, or in the industry. The main goal of this work is to study the feasibility to machining of non-cylindrical holes by a tool in rotation using CNC machine tools. That always has been offering obstacles to manufacturing industry by the difficulty of fabrication. Thus, the process presented on this work will machining a square hole with the same configuration of tools and systems for fixation of the parts, used for a cylindrical drilling, so common to industry. This intends to reduce the costs of fabrication and make easier to get non-cylindrical drilling using resources of the programmable equipment which are working at the shops. From a math model on, the machine is programmed to execute synchronized movements between the rotation and the displacements of the axis of the tool. Different programs were tested in different CNC machine tools, with different controllers, with and no resources for high speed, with different quantity of programmed points, with linear and circular interpolations. From the experiments, it was analyzed the configuration of the machines, the capacity for execution of the controller installed, the speed developed by machine at the operation and the geometry of the square holes. The experiments show that to machine a square hole, the controllers must be able to control a rotating axis itself, beyond to synchronize three axis. The critical to this kind of operation is the speed developed by the machine, being the most significant factor, the time the controller needs to process the block of programming, independently the activation of resources for high speed, linear or circular interpolations. It was verified than as larger the amount of points to compose the trajectory of the center of tool, better will be the geometry of the hole. Thus, the CNC machine tools in operation in the industry are able to machine the non-cylindrical drilling in a way very closely the cylindrical drilling as the time of machining and the fixing system of the tool and parts, requiring a programming that synchronizes the main spindle installed in any machine tool / Mestrado / Materiais e Processos de Fabricação / Mestre em Engenharia Mecânica

Esta tese tem por objetivo estudar a precisão de uma nova estrutura robótica para operações de fresamento, em substituição às convencionais maquinas-ferramentas seriais, especialmente as fresadoras e os centros de usinagem CNC. A estrutura proposta está baseada no conceito da cinemática paralela, tendo a análise da precisão sido realizada em função do mapeamento dos erros de posicionamento da ferramenta de corte dentro do espaço de trabalho disponível, durante operação de fresamento de acabamento, aplicando modelagem matemática. A motivação está na busca por altos desempenhos e as estruturas robóticas paralelas possuem diversas vantagens perante as estruturas seriais: construção modular, massa reduzida, altas velocidades/acelerações. Por outro lado, há ainda problemas a serem solucionados, como: garantia da precisão, otimização do espaço de trabalho e redução/eliminação de singularidades. A metodologia aplicada no desenvolvimento deste trabalho compreende quatro etapas: a proposta de uma nova estrutura robótica desenvolvida a partir de métodos de síntese existentes; o desenvolvimento de modelos matemáticos para caracterizar o seu comportamento cinemático; a identificação das fontes de erro que influenciam no desvio de posição da ferramenta; a elaboração de modelos matemáticos e algorítmos computacionais para analisar o grau de influência de cada fonte de erro identificada. Desenvolvemos uma estrutura robótica de topologia assimétrica 2UPS+PRP, com as seguintes características: mobilidade 3 com três translações no espaço, reduzido número de componentes e movimento na direção z independente dos movimentos nas direções x e y. Apresentamos os algoritmos computacionais para mapear os erros cinemáticos, geométricos e elásticos através da discretização do espaço de trabalho disponível, baseado nas matrizes Jacobianas e no princípio do trabalho virtual. Com relação aos mapeamentos dos desvios de posição da ferramenta obtidos, chegamos a algumas conclusões. Os maiores erros cinemáticos ocorreram quando as imprecisões impostas aos dois membros motores laterais tinham sinais contrários. Os erros geométricos com tolerâncias dimensionais na classe de trabalho IT5, foram os mais relevantes dentre os erros considerados. Os erros elásticos, considerando forças de usinagem de acabamento, foram os menos relevantes entre os erros considerados, sendo expressiva a influência da rigidez das juntas universais e esféricas. A utilização do princípio do trabalho virtual, com parâmetros de rigidez concentrados, mostrou ser eficaz e eficiente, comparado ao SMA (análise da matriz estrutural) e ao FEM (método dos elementos finitos), devido ao menor trabalho para o desenvolvimento da sua formulação e ao tempo computacional reduzido para o seu processamento. / This thesis has the purpose to study the precision of a new robotic structure for milling operations, in substitution to the conventional serial machine-tools, specialy the CNC milling machines and cutting centers. The proposed structure is based on the parallel kinematics concept and the precision analysis was realized, applying mathematical models, to obtain the positioning errors mapping of the cutting tool in the available workspace, during finishing milling operations. The motivation is on the search higher performances and the parallel robotic structures have several advantages to the serial structures: modular construction, lightness, high velocities/acelerations. Otherwise, there are still problems to be solved, like: guaranty of precision, workspace optimization and reduction/elimination of singularities. The methodology applied for the development of this work involves four steps: the proposal of a new robotic structure developed using existing synthesis methods; the development of mathematical models to characterize its kinematic behavior; the error sources identification that influences the deviation of the tool position; the elaboration of mathematical models and computer algorithms to analyse the influence level of each identified error source. We developed one assymmetric robotic structure 2UPS+PRP, with the following characteristics: mobility 3 with three translations in the space, reduced number of componentes and displacement in z direction independent from the displacents in the x and y directions. We presented the computer algorithms to map the kinematic, geometric and elastic errors, throw the discretization of the available workspace, based on the Jacobian matrices and the virtual work principle. With regard to the tool position deviation mappings obtained, we reach to some conclusions. The major kinematic errors occurred when the imprecisions imposed to the two lateral actuatores had opposed signals. The geometric errors with dimensional tolerances in the IT5 work class, were the more relevant among the considered errors. The elastic errors, considering finishing manufacturing forces, were the less relevent among the considered errors, being expressive the influence of the rigidity of the universal and spherical jounts. The utilization of the virtual work principle and concentrated rigidity parameters, showed to be efficacious and efficient, compared to the SMA (astructural matrice analisis) and the FEM (finite elements methode), because of the minor work to develop its formulations end the reduced computer time to its prosecution.

No description available.

The primary barrier to the production of better machined parts is machine tool error. Present day applications are requiring closer machine part tolerances. The errors in dimensional part accuracy derive from the machine, in this case, a vertical two axis CNC lathe. A two axis vertical lathe can be utilized to produce a variety of parts ranging from cylindrical features to spherical features. A vertical lathe requires a spindle to rotate the work at speeds reaching 3000rpm, while simultaneously requiring the machine tool to be positioned in such a manner to remove material and produce an accurate part. For this to be possible, the machine tool must be precisely controlled in order to produce the correct contours on the part. There are many sources of errors to be considered in the two axis vertical lathe. Each axis of importance contains six degrees of freedom. The machine has linear displacement, angular, spindle thermal drift, straightness, parallelism, orthogonal, machine tool offset and roundness error. These error components must be measured in order to determine the resultant error. The characterization of the machine addresses thermal behavior and geometric errors. This thesis presents the approach of determining the machine tool errors and using these errors to transform the actual tool path closer to the nominal tool path via compensation schemes. One of these schemes uses a laser interferometer in conjunction with a homogenous transformation matrix to construct the compensated path for a circular arc, facing and turning. The other scheme uses a ball bar system to directly construct the compensated tool path for a circular arc. Test parts were created to verify the improvement of the part accuracy using the compensated tool paths.

The manufacturing process has been a heavily studied area over the past century. The study completed herein has established a foundation for the future of manufacturing research. The next step of this industry is to become proficient at the micro and nano scale levels of manufacturing. In order to accomplish this goal, the modeling of machining system needs to be completely understood throughout the entire process. In effort to attack this problem, this study will focus on the boundaries present in machining systems; and will define and interpret the associated phenomena. This particular focus is selected since nearly all manufacturing related studies concentrate on continuous processes; which by definition considers only one particular operation. There is a need to understand the phenomena corresponding to interactions of multiple processes of manufacturing systems. As a means to this end, the nonlinear phenomena associated in the continuous domains of machining systems will be modeled as linear to ensure the boundary interactions are clearly observed. Interference of additional nonlinearities is not the focus of this research. In this dissertation, the mechanical model for a widely accepted machine-tool system is presented. The state and continuous domains are defined with respect to the boundaries in this system (contact and frictional force acting at the point of tool and work-piece contact). The switching sets defining plane boundaries for the continuous systems of this machine-tool will be defined and studied herein. The forces and force products, at the point of switching from one continuous system to another, govern the pass-ability of the machine-tool through the respective boundary. The forces and force product components at the switching points are derived according to discontinuous systems theory Luo [1]. Mapping definitions and notations are developed through the switching sets for each of the boundaries. A mapping structure and notation for periodic interrupted cutting, non-cutting and chip seizure motions are defined. The interruption of the chip flow for a machining system will be investigated through a range of system parameters. The prediction of interrupted periodic cutting, non-cutting and chip seizure motion will be completed via closed form solutions for this machine-tool. The state of this system is defined to utilize the theory of Luo [1]. This is necessary to properly handle the frictional force boundary at the chip/tool interface, the onset of cutting boundary and the contact boundary between the tool and work-pieces. The predictions by this method will be verified via numerical simulation and comparison to existing research. A goal of this research is to illustrate the effects of the dynamical systems interacting at the frictional force (chip/tool) boundary and the chip onset of growth and vanishing boundary. The parameter space for this machine-tool model is studied through numerical and analytical predictions, which provide limits on the existence of interrupted periodic cutting, non-cutting and chip seizure motions.

Parallel Kinematic Mechanisms (PKMs) are well suited for high-accuracy applications such as meso-milling. However, drawbacks such as limited platform tilting angle and high configuration dependency of stiffness often limit their usage. In this Thesis, a new six degree-of-freedom (dof) PKM architecture based on a 3×PPRS topology is proposed, in order to address these problems. The new PKM is presented, and its inverse kinematics and Jocobian matrix are derived. The kinematic relations are incorporated into MATLAB to calculate the workspace of the PKM. The stiffness of the new PKM is obtained using Finite Element Analysis (FEA), and configuration dependency of stiffness is investigated. The proposed new mechanism is compared with three similar existing 6-dof PKMs, and it is shown that the new PKM exhibits higher stiffness. Lastly, three meso-Milling Machine Tool prototypes were designed and built. In particular, Prototype III is based on the new mechanism.

Parallel Kinematic Mechanisms (PKMs) are well suited for high-accuracy applications such as meso-milling. However, drawbacks such as limited platform tilting angle and high configuration dependency of stiffness often limit their usage. In this Thesis, a new six degree-of-freedom (dof) PKM architecture based on a 3×PPRS topology is proposed, in order to address these problems. The new PKM is presented, and its inverse kinematics and Jocobian matrix are derived. The kinematic relations are incorporated into MATLAB to calculate the workspace of the PKM. The stiffness of the new PKM is obtained using Finite Element Analysis (FEA), and configuration dependency of stiffness is investigated. The proposed new mechanism is compared with three similar existing 6-dof PKMs, and it is shown that the new PKM exhibits higher stiffness. Lastly, three meso-Milling Machine Tool prototypes were designed and built. In particular, Prototype III is based on the new mechanism.

Esta tese tem por objetivo estudar a precisão de uma nova estrutura robótica para operações de fresamento, em substituição às convencionais maquinas-ferramentas seriais, especialmente as fresadoras e os centros de usinagem CNC. A estrutura proposta está baseada no conceito da cinemática paralela, tendo a análise da precisão sido realizada em função do mapeamento dos erros de posicionamento da ferramenta de corte dentro do espaço de trabalho disponível, durante operação de fresamento de acabamento, aplicando modelagem matemática. A motivação está na busca por altos desempenhos e as estruturas robóticas paralelas possuem diversas vantagens perante as estruturas seriais: construção modular, massa reduzida, altas velocidades/acelerações. Por outro lado, há ainda problemas a serem solucionados, como: garantia da precisão, otimização do espaço de trabalho e redução/eliminação de singularidades. A metodologia aplicada no desenvolvimento deste trabalho compreende quatro etapas: a proposta de uma nova estrutura robótica desenvolvida a partir de métodos de síntese existentes; o desenvolvimento de modelos matemáticos para caracterizar o seu comportamento cinemático; a identificação das fontes de erro que influenciam no desvio de posição da ferramenta; a elaboração de modelos matemáticos e algorítmos computacionais para analisar o grau de influência de cada fonte de erro identificada. Desenvolvemos uma estrutura robótica de topologia assimétrica 2UPS+PRP, com as seguintes características: mobilidade 3 com três translações no espaço, reduzido número de componentes e movimento na direção z independente dos movimentos nas direções x e y. Apresentamos os algoritmos computacionais para mapear os erros cinemáticos, geométricos e elásticos através da discretização do espaço de trabalho disponível, baseado nas matrizes Jacobianas e no princípio do trabalho virtual. Com relação aos mapeamentos dos desvios de posição da ferramenta obtidos, chegamos a algumas conclusões. Os maiores erros cinemáticos ocorreram quando as imprecisões impostas aos dois membros motores laterais tinham sinais contrários. Os erros geométricos com tolerâncias dimensionais na classe de trabalho IT5, foram os mais relevantes dentre os erros considerados. Os erros elásticos, considerando forças de usinagem de acabamento, foram os menos relevantes entre os erros considerados, sendo expressiva a influência da rigidez das juntas universais e esféricas. A utilização do princípio do trabalho virtual, com parâmetros de rigidez concentrados, mostrou ser eficaz e eficiente, comparado ao SMA (análise da matriz estrutural) e ao FEM (método dos elementos finitos), devido ao menor trabalho para o desenvolvimento da sua formulação e ao tempo computacional reduzido para o seu processamento. / This thesis has the purpose to study the precision of a new robotic structure for milling operations, in substitution to the conventional serial machine-tools, specialy the CNC milling machines and cutting centers. The proposed structure is based on the parallel kinematics concept and the precision analysis was realized, applying mathematical models, to obtain the positioning errors mapping of the cutting tool in the available workspace, during finishing milling operations. The motivation is on the search higher performances and the parallel robotic structures have several advantages to the serial structures: modular construction, lightness, high velocities/acelerations. Otherwise, there are still problems to be solved, like: guaranty of precision, workspace optimization and reduction/elimination of singularities. The methodology applied for the development of this work involves four steps: the proposal of a new robotic structure developed using existing synthesis methods; the development of mathematical models to characterize its kinematic behavior; the error sources identification that influences the deviation of the tool position; the elaboration of mathematical models and computer algorithms to analyse the influence level of each identified error source. We developed one assymmetric robotic structure 2UPS+PRP, with the following characteristics: mobility 3 with three translations in the space, reduced number of componentes and displacement in z direction independent from the displacents in the x and y directions. We presented the computer algorithms to map the kinematic, geometric and elastic errors, throw the discretization of the available workspace, based on the Jacobian matrices and the virtual work principle. With regard to the tool position deviation mappings obtained, we reach to some conclusions. The major kinematic errors occurred when the imprecisions imposed to the two lateral actuatores had opposed signals. The geometric errors with dimensional tolerances in the IT5 work class, were the more relevant among the considered errors. The elastic errors, considering finishing manufacturing forces, were the less relevent among the considered errors, being expressive the influence of the rigidity of the universal and spherical jounts. The utilization of the virtual work principle and concentrated rigidity parameters, showed to be efficacious and efficient, compared to the SMA (astructural matrice analisis) and the FEM (finite elements methode), because of the minor work to develop its formulations end the reduced computer time to its prosecution.

This project aims to present machine tool characteristics which may induce limiting factors in terms of flexibility. The aim is also to present a current state description of the machine tools in the production system regarding their characteristics in terms of quantifiable results. This refers to visual presentation in the form of graphs of the distribution of these characteristics among the different machine tools. A literature study was conducted to attain knowledge of machine tools and how the literature defines machine tool flexibility. Based on this, the flexibility parameters were identified. The result illustrates the current state description of the machine tools found in Volvo truck’s factory in Köping. These machine tools are lathe machines, machine centers, gear cutting machines and grinding machines. The result presents a percentage breakdown for each parameter for each of the machine types regarding the number of machines which possess a specific characteristic. The result displayed various cases of data missing. In many cases only a small percentage of data was missing, thus this result should be a sufficient representation of the situation. Meanwhile in other cases more data was missing and it leads to the result being less accurate. Overall, the acquired data in most cases should be sufficient to provide a current state description of the machines in the factory. There is no clear definition of flexibility referenced by the literature, hence it is difficult to conduct a quantitative evaluation. Moreover, there are many parameters presented in this work which emphasizes the multidimensional complexity of the problem. The parameters presented in this project directly influence the type of operations required, geometrical complexity of the workpiece, number of setups and size of workpiece which the machine is capable of handling. The machines have been grouped into the four categories mentioned above. This was done to reduce the complexity of the problem, hence not investigating each sub-category of machine (for example hobbing, skiving, etc.) The work has chosen not to group the machines based on the article they process as this would require additional knowledge of the layout and flow of material in the factory. The chosen approach will provide more of a generic visualization. A method has been developed to present a current state description of a manufacturing system regarding machine tool flexibility and how they can be evaluated. This process includes data collection and documentation of machines tools for the flexibility parameters. Hence, it can be presented how the machines within each machine type possess a specific attribute in terms of numbers or fit within a certain interval. The purpose is to present visual results of the data to illustrate for the reader the distribution of the machine characteristics for each of the machine types and parameters. / Detta projekt har som mål att presentera egenskaper hos bearbetningsmaskiner som kan medföra begränsande faktorer kopplat till flexibilitet. Målet är också att presentera en nulägesbeskrivning av bearbetningsmaskinernas egenskaper i produktionssystemet i form av kvantifierbara resultat. Detta refererar till visuella presentationer i form av grafer angående distribueringen av dessa egenskaper bland de olika bearbetningsmaskinerna. En litteraturstudie har genomförts för att tillhandahålla kunskaper om bearbetningsmaskiner och hur litteraturen definierar flexibilitet hos bearbetningsmaskiner. Resultatet illustrerar nulägesbeskrivningen av bearbetningsmaskinerna som befinner sig i Volvo Trucks fabrik i Köping. Dessa bearbetningsmaskiner är svarvar, fleroperationsmaskiner, kuggbearbetningsmaskiner och slipmaskiner. Resultatet visar en procentuell uppdelning av varje parameter for varje maskintyp, angående antalet maskiner som besitter en viss typ av egenskap. Resultatet visade på olika fall av saknad av data. I många fall saknades endast en liten andel av data, därmed bör detta resultat ge en tillräcklig representation av situationen. I andra fall saknades mer data och det leder till att resultatet blir mindre exakt. Överlag bör den insamlade datan i de flesta fall vara tillräcklig för att presentera en nulägesbeskrivning av maskinerna i fabriken. Det finns ingen tydlig definition av flexibilitet som nämns i litteraturen, därmed medför detta svårigheter att utföra en kvantitativ utvärdering. Dessutom presenteras det många olika parametrar i detta arbete, vilket understryker problemets flerdimensionella komplexitet. Parametrarna presenterade i detta arbete påverkar direkt vilken typ av operation som behövs, geometriska komplexiteten av arbetsstycket, antalet uppspänningar och storleken på arbetsstycket som maskinen kan hantera. Maskinerna har grupperats i fyra olika kategorier som nämndes ovan. Detta gjordes för att minska komplexiteten av problemet, därmed undersöks inte underkategorierna av maskinerna (till exempel hobbing skiving etcetera). Arbetet har valt att inte gruppera maskinerna baserat på vilken artikel de bearbetar, eftersom detta skulle behöva ytterligare kunskaper om layouten och flödet av material i fabriken. Det valda tillvägagångssättet ger en mer generell visualisering. En metod har tagits fram för att presentera en nulägesbeskrivning av ett produktionssystem med avseende på flexibiliteten hos bearbetningsmaskiner och hur de kan utvärderas. Denna process inkluderar datainsamling och dokumentation av flexibilitetsparametrarna hos bearbetningsmaskinerna. Därmed kan det presenteras hur maskinerna inom varje maskintyp besitter en specifik egenskap i form av siffror eller passar inom ett specifikt intervall. Syftet är att presentera visuella resultat av datan för att illustrera för läsaren om distribueringen av maskinegenskaperna för varje maskintyp och parameter.

On-machine inspection (OMI) via on-machine probing (OMP) is a technology that has the potential to provide a step change in the manufacturing of high precision products. Bringing product inspection closer to the machining process is very attractive proposition for many manufacturers who demand ever better quality, process control and efficiency from their manufacturing systems. However, there is a shortness of understanding, experience, and knowledge with regards to efficiently implementing OMI on industrially-based multi-axis machine tools. Coupled with the risks associated to this disruptive technology, these are major obstacles preventing OMI from being confidently adopted in many high precision manufacturing environments. The research pursued in this thesis investigates the concept of enabling high precision machine tools as measurement devices and focuses upon the question of: “How can traceable on-machine inspection be enabled and sustained in an industrial environment?” As highlighted by the literature and state-of-the-art review, much research and development focuses on the technology surrounding particular aspects of machine tool metrology and measurement whether this is theory, hardware, software, or simulation. Little research has been performed in terms of confirming the viability of industrial OMI and the systematic and holistic application of existing and new technology to enable optimal intervention. This EngD research has contributed towards the use of industrial machine tools as traceable measurement systems. Through the test cases performed, the novel concepts proposed, and solutions tested, a series of fundamental questions have been addressed. Thus, providing new knowledge and use to future researchers, engineers, consultants and manufacturing professionals.