Orientador: Anselmo Eduardo Diniz / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-19T18:33:44Z (GMT). No. of bitstreams: 1 Aguiar_MarceloMendesde_M.pdf: 3795090 bytes, checksum: a76ee2a93e8e7595881459d7a6d71b50 (MD5) Previous issue date: 2012 / Resumo: Normalmente, a utilização de aços ferramenta endurecidos, juntamente com as formas complexas típicas das peças utilizadas na área de moldes e matrizes, oferecem dificuldade na usinagem por fresamento, principalmente nas operações de acabamento que exijam o uso de ferramentas longas. A técnica de fresamento HSM (High Speed Machining - usinagem em altas velocidades, ou ainda High Speed Milling - fresamento em altas velocidades) tem se tornado uma alternativa para realizar este tipo de usinagem, reduzindo, ou às vezes até eliminando operações de eletro-erosão e polimento. Tipicamente, as fresas de pastilhas de metal duro intercambiáveis tem sido usadas em operações de desbaste e semi-acabamento, enquanto nas operações de acabamento ou em usinagem de geometrias que exijam ferramentas com pequenos diâmetros ainda predomina o uso de fresas inteiriças. O objetivo principal deste estudo é avaliar a influência de cinco variáveis de processo de fresamento com alta velocidade de corte, sobre o acabamento da superfície usinada. A influência do desgaste das ferramentas sobre o acabamento superficial, ao longo de 400 minutos de usinagem, também foi avaliado, além de uma comparação entre ferramentas inteiriças de metal duro e ferramentas de pastilha intercambiável montada em corpo de metal duro, a fim de avaliar a viabilidade técnica do uso deste segundo tipo de ferramenta, em substituição às tradicionais fresas inteiriças utilizadas em operações de acabamento. Na maioria dos experimentos realizados, pequenos valores de rugosidade foram mantidos, demonstrando que operações de acabamento em aço ABNT H13 IM com dureza de 50 HRC é possível com vida longa de ferramenta, mesmo utilizando-se valor de 500 m/min para velocidade de corte. Além disto, a análise da influência das variáveis de processo utilizadas neste trabalho mostrou que é possível, sob algumas condições, utilizar tanto ferramentas inteiriças, quanto de pastilha intercambiável montada em corpo de metal duro em operações de acabamento / Abstract: Typically, the use of hardened tool steels, along with complex shapes typical of the parts used in the field of molds and dies, offer difficulty in machining by milling, mainly in finishing operations that demand the use of long tool. The HSM (High Speed Machining or High Speed Milling) has become a possible alternative for making this type of machining, reducing, or sometimes eliminating electric discharge machining and polishing operations. Usually, indexable carbide insert mills has been used for roughing and semi-finishing, while in finishing operations or when the machining geometries that require tools with small diameters the integral tools are used yet. The main objective of this study is to evaluate the influence of five process variables, with high cutting speed, on the finish of the machined surface. The influence of tool wear on surface finish through 400 minutes of milling was also evaluated, as well as a comparison between integral carbide mills and indexable insert mounted at cemented carbide toolholder endmills, in order to evaluate the technical feasibility of using this second type of tool, replacing the traditional integral carbide endmills used in finishing operations. In most experiments, small roughness values were maintained, showing that finishing operations on AISI H13 IM with a hardness of 50 HRC is possible with long tool life, even using the cutting speed of 500 m/min. Furthermore, the analysis of the influence of process variables used in this study showed that is possible, under some conditions, the use either integral carbide tools, or indexable insert mounted at cemented carbide toolholder endmills on finishing operations / Mestrado / Materiais e Processos de Fabricação / Mestre em Engenharia Mecânica

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Orientador: Anselmo Eduardo Diniz / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-07-23T21:54:22Z (GMT). No. of bitstreams: 1 Matsumoto_Hidekasu_D.pdf: 9333077 bytes, checksum: 51f227c51103bc62610f0c64d486742b (MD5) Previous issue date: 1998 / Resumo: Neste trabalho procurou-se estudar a viabilidade de se tornear aços no estado endurecido utilizando máquinas de projeto mecânico convencional (sem mancais hidrostáticos e com um certo desgaste) comandadas numericamente, com a finalidade substituir as operações de retificação. Para tanto, usinou-se dois tipos de corpos de prova, de aço ABNT 52100 temperado e revenido com dureza média de 60 HRc (Rockwell C), com ferramentas de corte de PCBN (65% de CBN) e cerâmica mista ('Al IND. 2¿ 'O IND. 3¿ + TiC) encontradas no mercado. Monitorou-se os ensaios via corrente do motor principal e emissão acústica, com a finalidade de determinar o momento da substituição da ferramenta de corte. Após a análise dos resultados, chegou-se às seguintes conclusões: a) é possível substituir as operações de retificação por torneamento com máquina de projeto mecânico convencional, uma vez que se obteve qualidade IT5 e rugosidade menor que Ra = 0,6 'mu¿m, com vidas das ferramentas suficientemente longas para determinadas aplicações; b) os métodos de análise dos sinais de emissão acústica e corrente do motor utilizados, não se mostraram adequados para indicar o momento da troca da ferramenta; c) em geral, a ferramenta cerâmica apresentou vida média maior que a ferramenta de PCBN, porém com uma dispersão também maior / Abstract: The main goal of this work is to study the feasibility of turning hardened steels using a lathe with a conventional mechanical design (without hydrostatic bearings), aiming to replace grinding operations. For this purpose, two kinds of quenched and tempered 52100 steel workpieces were machined, with average hardness of 60 HRc, using PCBN (65% of CBN) and mixed ceramic ('Al IND 2¿¿O IND. 3¿ + TiC) tools. Both the electrical current of the main motor and the acoustic emission were monitored, aiming to automatically establish the moment to replace the tool. After the result analyses, the following conclusions were drawn: a) it is possible to replace grinding operations by turning with a conventional mechanical design lathe, since the workpiece quality obtained was within IT5 and the surface roughness was below Ra = 0.6 ' 'mu¿m, with tool life long enough for this kind of applications; b) the tool life monitoring through acoustic emission and electrical current of the main motor did not show to be suitable to establish the moment to replace the tool; c) in general, mixed ceramic tool had longer average toollife than PCBN tool, but presented larger scatter / Doutorado / Materiais e Processos de Fabricação / Doutor em Engenharia Mecânica

This licentiate thesis has the main focus on evaluation of the wear of coated and uncoated polycrystalline cubic boron nitride cutting tool used in cutting operations against hardened steel. And to exam the surface finish and integrity of the work material used. Harder work material, higher cutting speed and cost reductions result in the development of harder and more wear resistance cutting tools. Although PCBN cutting tools have been used in over 30 years, little work have been done on PVD coated PCBN cutting tools. Therefore hard turning and hard milling experiments with PVD coated and uncoated cutting tools have been performed and evaluated. The coatings used in the present study are TiSiN and TiAlN. The wear scar and surface integrity have been examined with help of several different characterization techniques, for example scanning electron microscopy and Auger electron spectroscopy.   The results showed that the PCBN cutting tools used displayed crater wear, flank wear and edge micro chipping. While the influence of the coating on the crater and flank wear was very small and the coating showed a high tendency to spalling. Scratch testing of coated PCBN showed that, the TiAlN coating resulted in major adhesive fractures. This displays the importance of understanding the effect of different types of lapping/grinding processes in the pre-treatment of hard and super hard substrate materials and the amount and type of damage that they can create. For the cutting tools used in turning, patches of a adhered layer, mainly consisting of FexOy were shown at both the crater and flank. And for the cutting tools used in milling a tribofilm consisting of SixOy covered the crater. A combination of tribochemical reactions, adhesive wear and mild abrasive wear is believed to control the flank and crater wear of the PCBN cutting tools. On a microscopic scale the difference phases of the PCBN cutting tool used in turning showed different wear characteristics. The machined surface of the work material showed a smooth surface with a Ra-value in the range of 100-200 nm for the turned surface and 100-150 nm for the milled surface. With increasing crater and flank wear in combination with edge chipping the machined surface becomes rougher and showed a higher Ra-value. For the cutting tools used in milling the tendency to micro edge chipping was significant higher when milling the tools steels showing a higher hard phase content and a lower heat conductivity resulting in higher mechanical and thermal stresses at the cutting edge.

This thesis is worked like experimental design vertical milling machine and design for future. Design was proceeding from numerically controlled vertical milling machines, and milling machine is intented for small machining of shaped areas. Milling head and body of machines are associaded in to one shape. for this thesis was serving technical documents milling machines from company TOS Kuřim. The Machines are names FGS 63 CNC, FGS 50/63, FGS 63B, FGN (Q) 63 CNC.

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Technical and Vocational Education and Training (TVET) is an indispensable part of the educational system that sustains significant responsibilities in creating sophisticated, high-skilled, and application-oriented talents and their comprehensive moral development. TVET metal cutting and welding teachers' learning in the workplace is a practice-based, complex cross-integration process of teachers' knowledge growth, competence acquisition, and professional development that links actual work processes and on-the-job activities. Workplace learning is undergoing a shift from a focus on teacher knowledge, expertise, and teaching methods, to an increasing focus on promoting instructional improvements centred on “student learning” (Imants & Van Veen, 2010). This research uses qualitative research methods to explore teachers' real and complex learning and development conditions, enrich the existing theoretical system of teachers' professional learning in the field of TVET metal cutting and welding based on actual work situations, and further deepen these teachers' professional development awareness. This study, which employs reflection level theory (Hartmann, 2005), situated learning theory (Lave & Wenger, 1991), action learning theory (Revans, 1982; 1998), and constructivism (Brooks & Brooks, 1999; Vygotsky & Cole, 1978; Piaget, 1970) as theoretical underpinnings, is guided by the following research questions: • What learning activities do TVET metal cutting and welding teachers utilize to learn in the workplace? • What factors (e.g., personal characteristics, working conditions) positively influence or restrict the involvement of TVET metal cutting and welding teachers in workplace learning? • What learning outcomes do TVET metal cutting and welding teachers perceive as professional development? Fourteen Chinese TVET instructors in the field of metal cutting and welding participated in this study. Semi-structured interviews, observations, and documentary material were chosen as the main strategies for collecting data. Hartmann's (2005) “the theory and methods of reflection levels” and Creswell's (2012) “six interrelated steps” (p.261) are utilized to guide the process of organizing, transforming, modelling, and interpreting data collected from these 14 teachers. Research Findings encompass three parts: Research Findings - Part I Based on qualitative data, the research findings (Part I) indicate that the main workplace learning activities of TVET metal cutting and welding teachers include four dimensions: learning by doing, learning through work-related interactions with others, reflection, and learning from media. The dimension of 'learning by doing' covers practical enterprise activities, participating in the staff group's skill competition, self-directed learning activities during lesson planning, the training and practice, using cloud-based teaching platforms, writing teaching journal/teaching logs, learning by teaching and experimentation, participation in the development and evaluation of curriculum implementation standards, involvement in school-based curriculum development. The dimension of 'learning through work-related interactions with others' encompasses lesson observation, collaborative group study, learning from experts, colleagues, trainees, etc. The dimension of 'reflection' involves teaching experience reflection and feedback reflection. The dimension of 'learning from media' encompasses viewing industrial documentaries, reading industry news, watching TV programs related to the teaching subjects, etc. Research Findings - Part II The research findings (Part II) show that the main factors influencing the workplace learning of TVET metal cutting and welding teachers include facilitating and constraining factors. The facilitating factors encompass career advancement, adequate learning resources, harmonious interpersonal relationships, occupational identity or professional self-identity, cooperative learning environments, and intrinsic motivation for the learning. The constraining factors cover teachers' heavy workloads, lack of time, insufficient school support, and the shortage of school facilities and equipment. Research Findings - Part III The research findings (part III) indicate that the outcomes of TVET metal cutting and welding teachers' workplace learning include three dimensions: accumulation of knowledge, competence enhancement, and emotional or attitudinal changes. The 'accumulation of knowledge' dimension covers educational theory, subject knowledge, teaching methods, and student psychology. The 'emotional or attitudinal change' dimension encompasses items like a greater love for the teaching profession and being more open-minded. The dimension of 'competence enhancement' involves class management, instructional design and overall teaching skills, practical operation ability, collaborative communication skills, teaching evaluation skills, reflection skills, analytical competence, lifelong learning ability, resource integration capability, etc.

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<p>A bench scale tribometer, developed at the McMaster Manufacturing Research Institute (MMRI) was designed for mimicking the friction and wear conditions on the rake face of a metal cutting tool. It provides insight into the performance of cutting tools operating under high stress and high temperature machining conditions. It saves test material costs, reduces machine downtime for testing, increases the number of test replicates and effectively adds a reliable testing tool to characterize metal cutting operations.</p> <p>A detailed investigation into the stress distribution, temperature profile and indentation pattern has been performed in order to verify the ability of the device to capture the machining environment and to gain a better understanding of the friction effects and wear conditions. The investigation used finite element analysis to simulate the MMRI’s tribometer with the FEA results compared to the experimental results. This data was then used to tune the operating conditions of the tribometer to improve its ability to simulate the machining environment.<strong></strong></p> / Master of Applied Science (MASc)

<p>The objective of this research was the further development and characterization of a heavy load, high temperature pin on disc tribometer. The goal of performing this testing on the tribometer is to simulate realistic machining conditions experienced between a tool and workpiece ‘offline’ in order to reduce the number of real machining trials used to select a tool coating and subsequently optimize cutting parameters. This approach is based on the understanding that a change in the cutting speed can alter the tool-chip interface temperature profile, which can change the coefficient of friction (COF) between the tool and workpiece and impact the tool wear mechanisms and rate. Significant modifications were introduced to the tribometer to increase its functionality; a resistance welder was integrated into the setup, and a completely new, fully automated Graphical User Interface was designed using National Instruments Labview software to allow for more careful control of all interacting components and variables. Careful investigations were carried out to understand the sensitivity of COF measurements to various input parameters in order to gain increased confidence in the meaning of COF measurements. Finally, various tool and workpiece material pairs were tested from room temperature to upwards of 900°C near the pin-disc interface and efforts were made to correlate the resulting COF measurements with machining data in the form of tool life and cutting force measurement. This research contributes towards the goals of improving machinability in two ways: first, by screening potential surface engineering treatments on the basis of reduced friction under machining relevant conditions of elevated contact stress and temperature; and secondly, by generating temperature-dependent friction data for different tool and workpiece material pairs that can be used to improve FE simulations of metal cutting.</p> / Master of Applied Science (MASc)