This diploma thesis is focused on cutting operation, particularly on turning. The theoretical part defines basic notion of cutting operation. It is especially focused on cutting operation in a broader context and in relation to economy.The practical part is focused on tools for turning, materials which the tools are made of and on the appropriateness of their use for different types of procedures and machined materials. The base of diploma thesis consists of a detailed analysis of selected turning operations in practice often associated with complications. This part contains a detailed analysis of the causes of emerging problems and proposed some solutions based on practical experience. The whole text is didactically conceived to be usable in teaching.

Orientador: Marcos Valério Ribeiro / Banca: José Vitor Candido de Souza / Banca: João Roberto Ferreira / Banca: Amauri Hassui / Banca: Izabel Fernanda Machado / Resumo: Com a constante evolução tecnológica nas áreas aeronáutica, espacial, automobilística, dentre outras, o uso de materiais com elevadas resistência mecânica e à corrosão em altas temperaturas tem sido cada vez mais necessário. Dentre os materiais que atendem a estes requisitos em temperaturas até 815 ºC está a liga à base de níquel Pyromet® 31V (N07032). Esta liga é utilizada na confecção de válvulas de exaustão em motores diesel de alta potência nas quais é exigida, além de resistência a altas temperaturas, uma grande resistência à sulfetação, à corrosão e à fluência. Entretanto, devido à sua grande resistência mecânica e baixa condutividade térmica, ocorre uma concentração de calor principalmente na interface cavaco-ferramenta dificultando assim a sua usinabilidade. Este trabalho teve como objetivo estudar a usinabilidade da liga Pyromet® 31V nas condições laminada à quente (42 HRC) e seguida de solubilização e envelhecimento (37 HRC) utilizando-se ferramentas de metal duro com e sem recobrimento, com lubrificação abundante e com a técnica de MQF. Em termos de vida da ferramenta, os melhores resultados para as ferramentas recobertas foram para avanços de 0,15 (laminadas) e 0,12 mm/rot. (solubilizadas). Devido à imprevisibilidade na formação do desgaste de entalhe e APC, não houve uma tendência clara de elevação ou queda na vida e/ou volume de material removido em função do avanço. Os mecanismos de desgaste atuantes nas ferramentas recobertas foram abrasão, attrition e martelamento e nas sem recobrimento foram difusão e abrasão. Na usinagem com MQF obteve-se bom acabamento superficial, vida razoável e reduzido volume de material removido. Já a ausência de recobrimento ocasionou uma redução de 70% no volume removido. Os cavacos gerados foram diversificados, mas predominantemente longos, destacando-se também a formação de cavacos duplos / Abstract: Considering the constant technological developments in the aeronautical, space, automotive and nuclear areas, among others, the use of materials with high mechanical strength and corrosion resistance at high temperatures has been increasingly necessary. Among the materials that meet the mechanical strength and corrosion properties at temperatures up to 815 °C one can find the nickel base alloy Pyromet® 31V (N07032). This alloy is commonly applied in the manufacturing of high power diesel engines exhaust valves, where it is required besides the high temperature resistance, high resistance to sulfide-containing environments, corrosion and good resistance to creep. However, due to its high mechanical strength and low thermal conductivity, it occurs concentration of heat in the workpiece-tool and tool-chip interfaces, resulting in low machinability. This work aimed to study the machinability, using the cemented carbide coated and uncoated tools, of the hot-rolled (42 HRC) and solubilizing-aging (37 HRC) conditions of the Pyromet® 31V alloy, using two conditions, abundant fluid and MQF techniques. The best results for tool life with coated tools were with 0.15 (hotrolled) and 0.12 mm/rev. (solubilizing-aging) feed rates. Due to the unpredictability in the formation of the notch wear and built-up edge (BUE) it wasn't observed a noticed tendency to increase or decrease in tool life and/or volume of removed material due to the feed rates. The wear mechanisms in coated tools were abrasion, attrition and hamming and in the uncoated tools were diffusion and abrasion. In the turning of this alloy with MQF, good surface finish, reasonable tool life and reduced volume of material removed were obtained. However, the absence of coated caused a 70% reduction in volume removed. The chips generated were of several types, but predominantly long, highlighting also the doubles chips formation / Doutor

abstract: Humans moving in the environment must frequently change walking speed and direction to negotiate obstacles and maintain balance. Maneuverability and stability requirements account for a significant part of daily life. While constant-average-velocity (CAV) human locomotion in walking and running has been studied extensively unsteady locomotion has received far less attention. Although some studies have described the biomechanics and neurophysiology of maneuvers, the underlying mechanisms that humans employ to control unsteady running are still not clear. My dissertation research investigated some of the biomechanical and behavioral strategies used for stable unsteady locomotion. First, I studied the behavioral level control of human sagittal plane running. I tested whether humans could control running using strategies consistent with simple and independent control laws that have been successfully used to control monopod robots. I found that humans use strategies that are consistent with the distributed feedback control strategies used by bouncing robots. Humans changed leg force rather than stance duration to control center of mass (COM) height. Humans adjusted foot placement relative to a "neutral point" to change running speed increment between consecutive flight phases, i.e. a "pogo-stick" rather than a "unicycle" strategy was adopted to change running speed. Body pitch angle was correlated by hip moments if a proportional-derivative relationship with time lags corresponding to pre-programmed reaction (87 ± 19 ms) was assumed. To better understand the mechanisms of performing successful maneuvers, I studied the functions of joints in the lower extremities to control COM speed and height. I found that during stance, the hip functioned as a power generator to change speed. The ankle switched between roles as a damper and torsional spring to contributing both to speed and elevation changes. The knee facilitated both speed and elevation control by absorbing mechanical energy, although its contribution was less than hip or ankle. Finally, I studied human turning in the horizontal plane. I used a morphological perturbation (increased body rotational inertia) to elicit compensational strategies used to control sidestep cutting turns. Humans use changes to initial body angular speed and body pre-rotation to prevent changes in braking forces. / Dissertation/Thesis / Ph.D. Kinesiology 2012

Vários fatores, tais como custos, qualidade, flexibilidade e tempo de resposta, levam a vantagens competitivas. Nas indústrias do ramo metal mecânico, os fatores custos e qualidade estão intimamente ligados ao surgimento de novos materiais de difícil usinagem (cujos comportamentos ainda são desconhecidos), e como conseqüência o surgimento de novos e caros materiais de ferramentas juntamente com as exigências de alta produção, lotes variados, faixas de tolerâncias cada vez mais estreitas e baixos custos de produção, o que têm extrapolado os limites e habilidades de operadores de máquinas. Quanto aos fatores flexibilidade e tempo de resposta, as indústrias têm apontado uma grande necessidade de informações confiáveis sobre desempenho da produção e informações sobre parâmetros tecnológicos das máquinas-ferramenta. Sistemas de apontamentos manuais mostram-se deficientes, quanto à confiabilidade, velocidade de atualização, detecção de não conformidades e outros fatores prejudiciais à produção, além de gerarem redundância de trabalho na coleta e alimentação de bancos de dados. O sistema proposto contribui para a satisfação dessas necessidades, utilizando-se de tecnologias de comunicação e de aquisição de dados, que propicia o monitoramento e supervisão de processos de torneamento. Permite o monitoramento da qualidade dimensional e indiretamente do desgaste de ferramentas, e ainda o compartilhamento de informações de chão de fábrica, em tempo real, para qualquer localidade via intranet e/ou internet, auxiliando na integração do sistema de manufatura. / Several factors, such as costs, quality, flexibility and response time, influence the competitive advantages. In the metal working industries, the factors cost and quality are closely linked to the appearance of new materials difficult to machine (whose behaviors are still ignored). As a consequence, the appearance of new and expensive tool materials, together with the demands for high production, varied batches, range of tolerances more and more narrow and low production costs, what have been extrapolating the limits and abilities of operator’s machine. With regards to the factors flexibility and response time, industries have been pointing to a need for reliable information about production performance and about machine-tools technological parameters. Systems of manual appointments are subject to lack of reliability, up date, detection of non conformities and other factors affecting negatively the production system. Additionally, they can generate work redundancy in the acquisition and database feeding. The proposed system contributes to achieve that need using communication and data acquisition technologies, that allows the monitoring and supervision of turning processes. It allows the monitoring of the dimensional quality and indirectly tools wear, as well as sharing shop floor information, in real time, with any place through intranet and/or Internet, aiding the integration of the manufacturing system.

Orientador: Anselmo Eduardo Diniz / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-17T11:44:38Z (GMT). No. of bitstreams: 1 Neves_Davi_D.pdf: 10536142 bytes, checksum: 795991ecdf9cb6dbe266a3307de5386d (MD5) Previous issue date: 2010 / Resumo: Uma característica dos revestimentos aplicados nas ferramentas de corte é a adesão. A adesão deficiente libera particulados duros e abrasivos resultantes da fragmentação prematura do revestimento, acelerando o desgaste das superfícies em contato. Na texturização, um laser de pulsos curtos e de alta frequência provoca, na interação com a superfície, uma mudança das propriedades advinda da fusão e ablação de material. Neste processo podem ocorrer a limpeza e a texturização simultâneas da superfície, dependendo da energia do pulso laser. Nesta tese foi avaliada a efetividade da texturização a laser como alternativa ao jateamento na preparação da superfície do substrato de ferramenta de metal duro antes da aplicação do revestimento. Após uma análise prévia dos efeitos do laser sobre o metal duro, dois conjuntos de substratos, um adequado a revestimento CVD e outro adequado a revestimento PVD, foram extraídos do processo produtivo antes do jateamento que antecede a aplicação do revestimento. Texturizados a laser em quatro diferentes condições, os substratos foram posteriormente recobertos com os respectivos filmes de PVD TiAlN e CVD TiCN+Al2O3+TiN. Comparadas com ferramentas convencionais, as ferramentas texturizadas a laser e revestidas por PVD foram superiores em testes de indentação e ensaios de torneamento. As ferramentas texturizadas a laser e revestidas por CVD apresentaram um desempenho inferior nos ensaios de indentação e torneamento. A comparação dos mecanismos de desgaste das ferramentas mostra que a texturização não elimina os mecanismos atuantes na ferramenta, mas altera a relação de importância na formação de seus desgastes. A texturização a laser não eliminou os defeitos produzidos pelo processo CVD na ferramenta, tornou-os mais graves, o que fez com que a ferramenta texturizada a laser apresentasse vida menor que a ferramenta convencional. Por outro lado, em ferramentas PVD, a ancoragem proporcionada pela maior rugosidade da superfície texturizada aumentou a adesão do revestimento com o substrato e, consequentemente, aumentar a vida da ferramenta / Abstract: Adhesion is one of the most important coating characteristics on cutting tools. Poor coating adhesion on the tool makes possible the coating fragmentation and the release of hard and abrasive particles. These particles interact with the tool surfaces accelerating tool wear. In texturing, a high frequency short pulse laser changes surface characteristics generating molten material and ablation. The surface cleaning and texturing can simultaneously occur, depending on the laser pulse energy. This thesis evaluated the effectiveness of laser texturing as an alternative to sand blasting for substrate surface preparation for tool surface coating. After a preliminary examination of laser surface cemented carbide interaction, two sets of substrates, a CVD coating suitable substrate and a PVD coating suitable substrate were taken from production process before blasting to coating application. These substrates were laser textured in four different conditions and then subsequently coated with the respective CVD TiCN+Al2O3+TiN film and PVD TiAlN film. The PVD coated laser texturized tool showed higher performance on indentation tests and turning tests in benchmark with conventional tools. The CVD coated laser-texturized tool was outperformed by conventional tools in the indentation test and turning test. The comparative evaluation of tool wear mechanisms shows that the texturing does not alter the wear mechanisms, but it changes the importance of them in tool wear. Therefore, laser texturizing did not eliminate the defects produced by the CVD process on the tool, instead, it made them more aggressive, what caused the laser texturized tool to have shorter life than the conventional one. On the other hand, in the PVD coated tools the anchoring caused by the higher roughness of the texturized surface could increase the coating adhesion on the substrate and, consequently, to increase tool life / Doutorado / Materiais e Processos de Fabricação / Doutor em Engenharia Mecânica

Orientador: Anselmo Eduardo Diniz / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-23T04:12:20Z (GMT). No. of bitstreams: 1 Carvalho_MartaReginaDelleDonne_M.pdf: 17580883 bytes, checksum: f1ff52988b201685207f750165cbc037 (MD5) Previous issue date: 2013 / Resumo: O resumo poderá ser visualizado no texto completo da tese digital / Abstract: The abstract is available with the full electronic document / Mestrado / Materiais e Processos de Fabricação / Mestra em Engenharia Mecânica

Orientador: Amauri Hassui / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-26T13:15:15Z (GMT). No. of bitstreams: 1 Silva_NelsonCoutinhoda_M.pdf: 3269726 bytes, checksum: cff763b01ba2bd71b0f177a7764ec81c (MD5) Previous issue date: 2014 / Resumo: O torneamento de aços endurecidos como alternativa a retificação cilíndrica, tem se tornado cada vez mais comum no meio industrial. Devido a melhorias do desempenho mecânico das máquinas, aliada aos avanços nos materiais de ferramenta, particularmente do PCBN, os bons resultados obtidos em aplicações e estudos realizados, vem estimulando cada vez mais essa prática. As diversas geometrias de peças utilizadas em componentes mecânicos submetem as ferramentas destinadas ao torneamento de aços endurecidos a condições de corte variadas, seja essas obtidas a partir de superfícies contínuas ou interrompidas. No entanto, a maior parte dos estudos já realizados, relacionados ao torneamento de aços endurecidos está voltada ao corte contínuo, fazendo do corte interrompido uma aplicação ainda pouco explorada. Este trabalho tem como objetivo estudar o comportamento da frequência de interrupção no torneamento de aços endurecidos com ferramenta de PCBN, além de sua interação com o ângulo de posição (?r) e velocidade de corte (vc). Para isso foram realizados experimentos de torneamento em corpos de prova com três frequências de interrupções diferentes, sendo um com baixa frequência de interrupção contendo dois rasgos, outro com média frequência de interrupção contendo quatro rasgos e finalmente outro com alta frequência de interrupção contendo oito rasgos, sendo esses transversais e equidistantes. Para a construção dos mesmos foi utilizado o aço ABNT 4340 com dureza entre 52 e 56 HRC, usando uma classe comercial de ferramenta PCBN 7525 (ISO H25) com alto teor de CBN (90%), recomendada para corte interrompido. Os parâmetros de saída analisados foram temperatura (°C), rugosidade (Ra), desgaste (VBmáx) e volume removido (mm3). Dentre as diversas conclusões desse trabalho, a principal delas indica que entre os parâmetros variados a frequência de interrupção é o que exerce maior influência sobre a temperatura e o volume removido, sendo que nos corpos de prova com maior frequência maiores volumes removidos foram alcançados, enquanto que nos corpos de prova com frequências menores, a temperatura atingiu níveis mais elevados / Abstract: Turning of hardened steels is becoming an important alternative to cylindrical grinding at industrial level. The increasing interest on this technique results from the good mechanical performance of the machine parts, which is accompanied by enhancements of the cutting tool materials, particularly PCBN, and the good results of using this technique, as reported in prior studies. Machine elements are characterized by a diversity of geometric forms. These characteristics promote that the cutting tools used for turning hardened steel are subjected to varying cutting conditions in both continuous and interrupted surfaces. However, most of the studies in this area have been related to turning hardened steels in continuous cutting. As a consequence, cutting of interrupted surfaces remains under-exploited. This work aims at studying the behavior of the interruption frequency during turning of hardened steels by using PCBN tools, as well as the interaction with the cutting tool¿s position angle (?r) and cutting speed (vc). For this, turning tests were performed on samples with three different interruption frequencies: a) low interruption frequency containing two slots, b) average interruption frequency containing four slots, and c) high interruption frequency containing eight slots. AISI 4340 steels with hardness between 52 and 56 HRC were used for manufacturing the samples. A commercial grade PCBN tool 7525 (ISO H25) with high CBN content (90%) was used as a cutting tool. The output parameters were temperature (°C), roughness (Ra), wear (VBmáx), and volume removed (mm3). Results indicate that the interruption frequency is the parameter that most affects the temperature and the volume removed. The samples mechanized at higher frequencies presented higher volume removed. Meanwhile, the samples turned with lower frequencies reached higher temperatures / Mestrado / Materiais e Processos de Fabricação / Mestre em Engenharia Mecânica

This diploma thesis deals with the choice of suitable VBD for longitudinal turning barrel steel OCHN3MFA. In the theoretical part, serving as a basis for the experimental part, the technology of turning, tooling and coating methods was analyzed. In the experimental part, ten VBDs were tested, eight of which were of cemented carbide and two of ceramic. The monitored parameters were force load and tool wear VB. From the evaluated load data and tool wear, a suitable VBD for turning barrel steel was selected. The most suitable VBD for turning barrel steel is VBD – G. Tools VBD – I and VBD – J from ceramics are inappropriate tools for turning barrel steel.

The goal of this thesis is the incorporation of the contactless measurement of surface temperature among other methods of temperature measurement. Technical preparation for experimental measuring on the machine-tool. Comparison of influence of cutting conditions on the development of surface temperature of workpiece during the machining process with usage of the camera ThermaCAM CS2000. The economical analysis of the contactless measurement of surface temperature is determined in the last part of this thesis.

In the introductory part of the thesis, there is a description of machining technologies used in the production of body. This is followed by a detailed analyse of the current technology of production of this component with an emphasis on finding its problematic parts, including a proposal of the options of the rationalization. After the methods of rationalization assesment, a new technological process was developed and the alternative tools were proposed. Considerable time and money savings were achieved by this rationalization. In the discussion section, there were designed some options of solving problems arising during the installation of this rationalization into working.