Submitted by Nadir Basilio (nadirsb@uninove.br) on 2016-06-01T14:21:08Z No. of bitstreams: 1 Fernando Santos De Oliveira.pdf: 3269879 bytes, checksum: 09ed535c5a81984aed10645fbbdb3f79 (MD5) / Made available in DSpace on 2016-06-01T14:21:08Z (GMT). No. of bitstreams: 1 Fernando Santos De Oliveira.pdf: 3269879 bytes, checksum: 09ed535c5a81984aed10645fbbdb3f79 (MD5) Previous issue date: 2015-04-07 / It is important that the machining processes are continually improved in order to provide competitive advantages and economic conditions for manufacturing companies. A very used manufacturing process, mainly because it is one of the few that allow obtaining small diameter internal thread, is the thread tapping with thread cutting taps. As such, thread tapping is one of the last process to be carried out and any failure can influence in production costs. One way to reduce costs is by increasing the useful life of the thread tap through the use of surface treatments, coatings or cutting fluids. Therefore, the main objective of this work is to evaluate the performance of the application of a dry impregnated lubrication on the surface of thread taps, with a focus on conventional tapping process improvement concerning tool useful life and, consequently, costs reduction. For this purpose, tests in the tapping process were performed using high speed steel taps in two conditions, i.e., treated or not with a dry impregnated lubrication. The results obtained allow to conclude that the procedure employed was appropriate, because it increased the tool useful life, reduced the tool wear, and maintained the thread quality, promoting a reduction in manufacturing costs. / É importante que os processos de usinagem sejam continuamente melhorados, de forma a oferecer vantagens competitivas e condições econômicas para as indústrias manufatureiras. Um processo de fabricação muito empregado, principalmente por ser um dos poucos a permitir a obtenção de roscas internas de pequeno diâmetro, é o processo de rosqueamento interno com machos. Tal processo, normalmente é um dos últimos a ser realizado e qualquer falha pode influenciar os custos de produção. Uma forma de minimizar os custos no processo de rosqueamento interno é a utilização de abordagens que visam otimizar a vida útil do macho de roscar por meio do uso de tratamentos superficiais, revestimentos ou fluidos de corte. Dessa forma, este trabalho tem como objetivo principal avaliar o desempenho da aplicação de um condicionador de metais na superfície de machos, com foco na melhoria do referido processo em relação à vida útil da ferramenta e, consequentemente, na redução de custos. Para tanto, ensaios foram realizados utilizando-se de machos de aço rápido em duas condições: tratados ou não com condicionador metálico. Os dados coletados foram analisados com apoio de recursos estatísticos para se verificar o nível de confiança das amostras. Os resultados obtidos permitem concluir que o procedimento utilizado foi adequado, pois aumentou a vida útil do macho, reduziu o nível de desgaste das ferramentas, mantendo-se a qualidade das roscas e, consequentemente, promoveu uma redução nos custos de fabricação.

The submitted work deals with issues of optical transmissions and its security. We will become familiar with a variety of transferability of information, based on which we can assess the advantages and disadvantages of each technology as compared to optical information transmission. Based on acquired information we will try to implement interception of optical communication of cable TV provider.

The project conceived within engineer‘s studies of branch 2303T002 is showing holder produce technology using by the company UniTools Press CZ Valašské Meziříčí. This holder is a part of car seat-adjusting system dedicated for Peugeot 308. According to the literary research, next part of this project is submitting two diferent solutions of produce technology and then it chooses the best one. The best one is chosen with the help of weight values table. The holder is produced in associated tool on press Arisa 400 with nominal force 4000 kN. The holder is manufactured from the roll of sheet steel S355MC (thickness 3mm). In the last part this project is suggesting the modification of produce technology in order to increase tapping tool working life and to increase the production productivity. Keywords: The steel S355MC, tapping, associated tool. y

This diploma thesis deals with HSS cutting taps performance in combination with very hard and tribological PVD coating application and their contribution to increasing of cutting properties. Then is described the mechanisms and forms of cutting tool wear. The goal of the experimental part of the thesis was determine, compare and subsequently evaluate cutting properties of threading tools using taps with different types of PVD coatings. During realization of the experiment, constant cutting conditions have been ensured and the only variable were the different types of coating layers. The result of the experiment was measurement of cutting torques depending on time and rate of wear of cutting tools. Measured value are statistically processed and drawn conclusion.

Bearbetningsprocesser är en viktig del av tillverkningsindustrin. Dessa företag måste kontinuerligt förbättra sina processer och göra dem mer effektiva, minska de ekologiska fotavtrycken och driftskostnaderna. Syftet med denna rapport är att förbättra en rund brotschningsprocess för ett bilföretag. Brotschverktyget är tillverkat av solid HSS och belagt med TiN, som dras genom ett hål i arbetsstycket. På grund av att flera skärkanter fungerar samtidigt är skärkraften hög. Med skärverktygets lågavlastningsvinkel spelar smörjmedlet en kritisk roll i brotschningsprocessen. Arbetet studerar olika skärvätskor i ett laboratorium, genom att simulera påverkan av skärvätskor i en brotschningsprocess med tappningsoperationer under liknande förhållanden. Momentvärdena och beteendet av processen har studerats för de olika smörjmedlen. Studien visade att smörjmedlet har en stor påverkan på vridmoment och spånbildningen. Relationen mellan smörjviskositet och smörjningsförmåga studerades. Dessutom undersöktes sambandet mellan spånbildning och vridmomentbeteende, vilket visar vikten av spånens utrymningskapacitet. Processen har utförts genom att använda olika typer smörjmedel för att undersöka deras påverkan på skärkrafterna och hur de utvecklades under hela processen. Resultaten och den efterföljande analysen har visat att viskositeten har stort inflytande i processen. Viskositeten är omvänt proportionell mot vätskans kapacitet för att komma åt vissa kritiska områden, vilket ökar friktionskrafterna och genereringen av långa spån. Både spånstorleken och smörjmedlets förmåga att utrymma har starka influenser på processen. / Machining processes are an important part of the manufacturing industry. Companies within the manufacturing industry are required to continuously improve their processes and make them more efficient, to reduce the ecological impact and operational costs. The aim of this thesis is to be able to improve a circular broaching process for an automotive company. The broaching tool is made from solid High-Speed Steel and TiN coated, which is pulled through a hole in the workpiece. Due to multiple cutting edges acting simultaneously, the cutting force is high. With a low relief angle of the cutting tool and low cutting speed, the lubricant plays a critical role in the broaching process. The thesis studies different cutting fluids in a laboratory, by simulating the impact of cutting fluids in a broaching process with tapping operations under similar conditions. The torques values and the behaviour of it during the process have been recorded for different lubricants. The lubricants were found to have a strong influence in the torque required and the chip formation. The relation between lubricant viscosity and lubrication performance was studied. In addition, the relation between chip formation and torque behaviour was explored, showing the importance of chip evacuation capacity. The process has been carried out by using different lubricants to examine the required cutting forces and how they evolved throughout the process. The results and the consecutive analysis have shown an influence of the viscosity in the process. The viscosity is inversely proportional to the capacity of the fluid to access certain critical areas, increasing the friction forces and the generation of long chips. Both the chip size and the ability of the lubricant to evacuate have strong influences on the process.

A mathematical model is developed to investigate the grazing dynamics of tapping mode atomic force microscopes (AFM) subjected to a base harmonic excitation. The nonlinear dynamics of the AFM microcantilever are studied in both of the monostable and bistable phases with the microcantilever tip being, respectively, located in the monostable and bistable regions of the static bifurcation diagram in the reference configuration. Free-vibration responses of the AFM probes, including the microcantilever natural frequencies and mode shapes, are determined. It is found that, for the parameters used in a practical operation of an AFM, the natural frequencies and mode shapes of the AFM microcantilever are almost the same as those of a free-end microcantilever with the same geometry and made of an identical material. A multimode Galerkin approximation is utilized to discretize the nonlinear partial-differential equation of motion and associated boundary conditions governing the cantilever response and obtain a set of nonlinearly coupled ordinary-differential equations (ODE) governing the time evolution of the system dynamics. The corresponding nonlinear ODE set is then solved using numerical integration schemes. A comprehensive numerical analysis is performed for a wide range of the excitation amplitude and frequency. The tip oscillations are examined using nonlinear dynamic tools through several examples. The non-smoothness in the tip/sample interaction model is treated rigorously. A higher-mode Galerkin analysis indicates that period doubling bifurcations and chaotic vibrations are possible in tapping mode microscopy for certain operating parameters. It is also found that a single-mode Galerkin approximation, which accurately predicts the tip nonlinear responses far from the sample, is not adequate for predicting all of the nonlinear phenomena exhibited by an AFM, such as grazing bifurcations, and leads to both quantitative and qualitative errors. A point-mass model is also developed based on the single-mode Galerkin procedure to compare with the present distributed-parameter model. In addition, a reduced-order model based on a differential quadrature method (DQM) is employed to explore the dynamics of the AFM probe in the bistable phase where the multimode Galerkin procedure is computationally expensive. We found that the DQM with a few grid points accurately predicts the static bifurcation diagram. Moreover, we found that the DQM is capable of precise prediction of the lowest natural frequencies of the microcantilever with only a few grid points. For the higher natural frequencies, however, a large number of grid points is required. We also found that the natural frequencies and mode shapes of the microcantilever about non-contact equilibrium positions are almost the same as those of the free-end microcantilever. On the other hand, free-vibration responses of the microcantilever about contact equilibrium positions are quite different from those of the free-end microcantilever. Moreover, we used the DQM to discretize the partial-differential equation governing the microcantilever motion and a finite-difference method (FDM) to calculate limit-cycle responses of the AFM tip. It is shown that a combination of the DQM and FDM applied, respectively, to discretize the spatial and temporal derivatives provides an efficient, accurate procedure to address the complicated dynamic behavior exhibited by the AFM probe. The procedure was, therefore, utilized to study the response of the microcantilever to a base harmonic excitation through several numerical examples. We found that the dynamics of the AFM probe in the bistable region is totally different from those in the monostable region. / Ph. D.

<p>Trajectory formation is an important quality of human movement wherein the analysis of its kinematic structure often permits inferences regarding the underlying sensorimotor organization. The studies reported herein aimed to reveal how task-specific encoding of saccades contribute to two movement models. We first examined saccades for changes in the evidence for online spatial corrections in response to different instances of visual tracking. Results from our first study indicated the sensorimotor operations associated with making timed series responses permitted unhindered operation of online corrections in predictive saccades. These saccades imposed a demand on spatial working memory without suffering diminished corrections typical of single delayed memory-guided saccades. Next, we queried the role of ventral stream visuomotor processing, as well as the contribution of basic stimulus features to explaining known modulations of online saccadic corrections. Our results are consistent with the explanation that ventral stream contribution to target metrics influence trajectory kinematics, but did not induce diminished online corrections if vision of that illusory target was available at saccade onset. Using another movement task, we examined how different saccadic tracking behaviours dissociated the contribution of various sensorimotor operations involved in oculomotor preparation and execution to eye-hand coupling. By observing changes in manual trajectory in an oculo-manual task, we contrasted the effects of saccadic tracking in predictive and reactive modes, overt and covert, horizontal and vertical, spatially congruent or perpendicular axes of primary motion relative to eye-hand coupling. From these data we concluded that saccadic encoding induced execution-dependent coupling, and optionally motor planning-dependent coupling when task constraints specified temporal synchrony between eye and hand movements. Moreover, eventual motor execution was a prerequisite for the emergence of oculomotor planning-dependent coupling effects. This implied no apparent contribution to the coupling dynamic as an exclusive function of shifts in the spatial allocation of attention without oculomotor output.</p> / Doctor of Philosophy (PhD)

In the automotive industry, Al-Si alloy is widely used for manufacturing of various engine parts. Machinability of die-cast Al-12Si alloy is challenging due to severe abrasion and adhesion wear of the tools. Form tapping is a common method for generating internal threads in engine blocks. It is usually a finishing process on a production line. An unexpected tap failure may lead to significant scrap and high rework costs. The objective of this research was to investigate the wear mechanisms of high-speed steel form taps when machining Al-12Si alloy. This research involved replicating the same process conditions as the industry partner to determine a feasible solution without changing the tap geometry or process parameters. A critical region of wear on the crest was identified where the aluminum adhesion was acute. Intense abrasion wear occurred on the crest and flanks due to hard silicon precipitates. In this study, two methods were proposed for measuring linear and volumetric wear on the chamfered threads. The second and third chamfered threads experienced the most significant wear on the tap. To improve wear-resistance of the form tap, PVD surface coatings were deposited on it. The preliminary tests of 12 surface coatings showed coating-delamination mostly on the critical region. A progressive wear study of the TiAlN coating showed an improvement in tap performance over the ZrN coating currently used. By the 4320th hole, the volumetric wear of the TiAlN coated tap was reduced by nearly 200% and 50% when compared against the uncoated and ZrN coated taps, respectively. / Thesis / Master of Applied Science (MASc)

In October 2001 , President George W. Bush issued an executive order authorizing the National Security Agency (NSA) to conduct secret wiretapping of telephone communications between U.S. citizens and terrorist suspects overseas in the wake of the September 11th terrorist attacks. The program, later called the Terrorist Surveillance Program (TSP), remained secret until December 2005, when the New York Times revealed the existence of the TSP. In January 2006, the American Civil Liberties Union (ACLU) filed suit in the United States District Court for the Eastern District of Michigan, claiming that the NSA's surveillance program violated the First and Fourth Amendments of the U.S. Constitution, as well as the separation of powers doctrine. The government argued that the program met constitutional scrutiny under the "special needs" doctrine warrant exception. Additionally, the Bush administration asserted that Congress specifically gave the President permission to authorize the program by its passing the Authorization for Use of Military Force (AUMF). This thesis analyzes the constitutionality of the domestic surveillance program by discussing the constitutional questions that the NSA's program elicits under the Fourth Amendment. Also, this thesis reviews the legality of the TSP under the Foreign Intelligence Surveillance Act (FISA). After an analysis of the Supreme Court's jurisprudence in Fourth Amendment, privacy, and eavesdropping cases, this thesis concludes that the NSA' s warrantless eavesdropping program most likely violates the Fourth Amendment and the separation of powers doctrine. Further, this thesis asserts that the TSP is illegal under the FISA and that the Executive lacks statutory authorization.

This research concerns the development and characterization of methylene bis (p-cyclohexyl isocyanate/butanediol) (HMDI/BD) based polyurethanes used in connection with surface-active anti-microbial polyurethanes. Previously studied polyurethanes having an isophorone diisocyanate/butanediol (IPDI/BD) hard block contaminated water during dynamic contact angle (DCA) analyses. This contamination by unknown species confounds results from biocidal studies and jeopardizes the use of the polyurethane as a matrix polyurethane. By contrast, polyurethanes with methylene bis (p-cyclohexyl isocyanate)/butanediol hard block showed no contamination during DCA analysis. For this reason, further study of HMDI/BD/PTMO polyurethanes was conducted. HMDI/BD polyurethanes were synthesized with 15-50wt% hard block and a soft block of PTMO-2000 or PTMO-1000 where PTMO-2000 is poly (tetramethylene oxide) with a molecular weight of 2000g/mol and PTMO-1000 has a molecular weight of 1000g/mol. Characterization was performed with FT-IR and 1H NMR spectroscopy to verify polyurethane composition as well as hard block percentage. Thermal characterization was performed with modulated differential scanning calorimetry (MDSC). From MDSC, the glass transition temperatures of the soft and hard block for polyurethanes with PTMO-2000 as the soft block were -80°C and 86°C, respectively. For corresponding polyurethanes containing PTMO-1000 as the soft block, the measured Tgs for the soft and hard segments were -55°C and 65°C, respectively. The disparity between the respective soft and hard segment Tgs of these polyurethanes of differing soft block molecular weights is due to increased phase mixing that causes an increase in soft block Tg and a decrease in hard block Tg for the PTMO-1000 polyurethanes. From dynamic contact angle analyses of HMDI/BD/PTMO polyurethanes, the advancing and receding contact angles gradually decreased with each cycle but approached 80° and 60°, respectively. Results from force-distance curves with flamed glass slides obtained before and after immersion of the polyurethane coatings indicated that no water contamination occurred. Tensile tests demonstrated that hard block percentage, soft block molecular weight, and the amount of chain extender influences mechanical properties. For example, increasing hard block weight percentage increases the modulus. HMDI/BD(30)/PTMO-2000 (PU-1), HMDI/BD(25)/PTMO-2000, (PU-2) and HMDI/BD(35)/PTMO-2000 (PU-10) exhibited the best elastomeric properties. As the final outcome, lack of contamination and good mechanical properties made PU-2 and PU-9 (HMDI/BD(50)/PTMO-1000) suitable candidates as polyurethane matrices for polymer surface modifier evaluation.