Dissertations / Theses on the topic 'Machining chip'
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Hagiwara, Masaya. "OPTIMIZATION OF MACHINING PERFORMANCE IN CONTOUR FINISH TURNING OPERATIONS." UKnowledge, 2005. http://uknowledge.uky.edu/gradschool_theses/341.
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Unlike straight turning, the effective cutting conditions and tool geometry in contour turning operations are changing with changing workpiece profile. This causes a wide variation in machining performance such as chip flow and chip breakability during the operation. This thesis presents a new methodology for optimizing the machining performance, namely, chip breakability and surface roughness in contour finish turning operations. First, a computer program to calculate the effective cutting conditions and tool geometry along the contour workpiece profile is developed. Second, a methodology to predict the chip side-flow for complex grooved tool inserts is formulated and integrated in the current predictive model for contour turning operations. Third, experimental databases are established and numerical data interpolation is applied to predict the cutting forces, chip shape and size, and surface roughness for 1045 steel work material. Finally, based on the machining performance predictions, a new optimization program is developed to determine the optimum cutting conditions in contour finish turning operations.
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Mahdi, Wathik Issa. "Tool contact stresses and chip formation in metal machining." Thesis, University of Bradford, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.254204.
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Olajire, Kabiru Ayinde. "Machining of aerospace steel alloys with coated carbides." Thesis, Coventry University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301195.
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Avanessian, Alfred. "An analysis of the effect of 3-D groove insert design on chip breaking chart." Link to electronic thesis, 2005. http://www.wpi.edu/Pubs/ETD/Available/etd-01255-110749/.
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Zhou, Li. "Machining chip-breaking prediction with grooved inserts in steel turning." Link to electronic thesis, 2002. http://www.wpi.edu/Pubs/ETD/Available/etd-0109102-140803.
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Zhou, Li. "Machining chip breaking prediction with grooved inserts in steel turning." Link to electronic thesis, 2001. http://www.wpi.edu/Pubs/ETD/Available/etd-0109102-140803.
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Brown, Charles Jeremy. "An investigation of tool stresses caused by unsteady chip formations in machining." Thesis, Queen's University Belfast, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.236295.
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Kishawy, Hossam Eldeen A. "Chip formation and surface integrity in high speed machining of hardened steel /." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0003/NQ42858.pdf.
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Khatri, Ashutosh Mahesh. "INVESTIGATING TOOL WEAR MECHANISM AND MICROSTRUCTURALCHANGES FOR CONVENTIONAL AND SUSTAINABLE MACHINING OFTITANIUM ALLOY." Miami University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=miami1533287855502478.
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Venkatachalam, Sivaramakrishnan. "Predictive Modeling for Ductile Machining of Brittle Materials." Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/19774.
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Brittle materials such as silicon, germanium, glass and ceramics are widely used in semiconductor, optical, micro-electronics and various other fields. Traditionally, grinding, polishing and lapping have been employed to achieve high tolerance in surface texture of silicon wafers in semiconductor applications, lenses for optical instruments etc. The conventional machining processes such as single point turning and milling are not conducive to brittle materials as they produce discontinuous chips owing to brittle failure at the shear plane before any tangible plastic flow occurs. In order to improve surface finish on machined brittle materials, ductile regime machining is being extensively studied lately. The process of machining brittle materials where the material is removed by plastic flow, thus leaving a crack free surface is known as ductile-regime machining. Ductile machining of brittle materials can produce surfaces of very high quality comparable with processes such as polishing, lapping etc. The objective of this project is to develop a comprehensive predictive model for ductile machining of brittle materials. The model would predict the critical undeformed chip thickness required to achieve ductile-regime machining. The input to the model includes tool geometry, workpiece material properties and machining process parameters. The fact that the scale of ductile regime machining is very small leads to a number of factors assuming significance which would otherwise be neglected. The effects of tool edge radius, grain size, grain boundaries, crystal orientation etc. are studied so as to make better predictions of forces and hence the critical undeformed chip thickness. The model is validated using a series of experiments with varying materials and cutting conditions. This research would aid in predicting forces and undeformed chip thickness values for micro-machining brittle materials given their material properties and process conditions. The output could be used to machine brittle materials without fracture and hence preserve their surface texture quality. The need for resorting to experimental trial and error is greatly reduced as the critical parameter, namely undeformed chip thickness, is predicted using this approach. This can in turn pave way for brittle materials to be utilized in a variety of applications.
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Zhang, Hong. "Plastic deformation and chip formation mechanisms during machining of copper, aluminum and an aluminum matrix composite." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ62306.pdf.
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Devotta, Ashwin Moris. "Characterization & modeling of chip flow angle & morphology in 2D & 3D turning process." Licentiate thesis, Högskolan Väst, Forskningsmiljön produktionsteknik(PTW), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:hv:diva-8671.
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Within manufacturing of metallic components, machining plays an important role and is of vital significance to ensure process reliability. From a cutting tool design perspective, tool macro geometry design based on physics based numerical modelling is highly needed that can predict chip morphology. The chip morphology describes the chip shape geometry and the chip curl geometry. The prediction of chip flow and chip shape is vital in predicting chip breakage, ensuring good chip evacuation and lower surface roughness. To this end, a platform where such a numerical model’s chip morphology prediction can be compared with experimental investigation is needed and is the focus of this work. The studied cutting processes are orthogonal cutting process and nose turning process. Numerical models that simulate the chip formation process are employed to predict the chip morphology and are accompanied by machining experiments. Computed tomography is used to scan the chips obtained from machining experiments and its ability to capture the variation in chip morphology is evaluated. For nose turning process, chip curl parameters during the cutting process are to be calculated. Kharkevich model is utilized in this regard to calculate the ‘chip in process’ chip curl parameters. High speed videography is used to measure the chip side flow angle during the cutting process experiments and are directly compared to physics based model predictions. The results show that the methodology developed provides the framework where advances in numerical models can be evaluated reliably from a chip morphology prediction capability view point for nose turning process. The numerical modeling results show that the chip morphology variation for varying cutting conditions is predicted qualitatively. The results of quantitative evaluation of chip morphology prediction shows that the error in prediction is too large to be used for predictive modelling purposes.
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Wince, Jaton Nakia. "Modeling chip formation in orthogonal metal cutting using finite element analysis." Master's thesis, Mississippi State : Mississippi State University, 2002. http://library.msstate.edu/etd/show.asp?etd=etd-07232002-154556.
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Menon, Thejas. "Full-field infrared thermography at tool-chip interface through transparent cutting tool while machining TI-6AL-4V." Thesis, Wichita State University, 2013. http://hdl.handle.net/10057/6382.
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Wong, Darrell. "Particleboard simulation model to improve machined surface quality." Thesis, University of British Columbia, 2007. http://hdl.handle.net/2429/247.
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Particleboard (PB) is a widely used panel material because of its physical properties and low cost. Unfortunately, cutting can degrade its surface creating rejects and increasing manufacturing costs. A major challenge is PB’s internal variability. Different particle and glue bond strength combinations can sometimes create high quality surfaces in one area and defects such as edge chipping in nearby areas.
This research examines methods of improving surface quality by examining PB characteristics and their interactions with the cutting tool. It also develops an analytical model and software tool that allows the effects of these factors to be simulated, thereby giving practical guidance and reducing the need for costly experiments. When PB is cut and the glue bond strength is weaker than the particle strength, particles are pulled out, leading to surface defects. When instead the glue bond strength is stronger than the particle strength, particles are smoothly cut, leading to a high quality surface.
PB is modeled as a matrix of particles each with stochastically assigned material and glue bond strengths. The PB model is layered allowing particles to be misaligned. Voids are modeled as missing particles.
PB cutting is modeled in three zones. In the finished material and tool tip zones, particles are compressed elastically and then crushed at constant stress. After failure, chip formation occurs in the chip formation zone. At large rake angles, the chip is modeled as a transversely loaded beam that can fail by cleavage at its base or tensile failure on its surface. At small rake angles, the chip is modeled as the resultant force acting on the plane from the tool tip through to the panel surface.
Experimental and simulation results show that cutting forces increase with depth of cut, glue content and particle strength. They decrease with rake angle. Glue bond strength can be increased to the equivalent particle strength through the selection of particle geometry and the subsequent increased glue bond efficiency, which increases the cut surface quality without the need for additional glue. Minimizing the size and frequency of voids and using larger rake angles can also increase surface quality.
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Aamir, Muhammad. "Simultaneous machining of aerospace structural materials using poly-drills." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2021. https://ro.ecu.edu.au/theses/2471.
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Despite the growth of composites and other lightweight materials, aluminium alloys remain an attractive choice for the aerospace industry due to their distinct manufacturing processes, good resistance to fatigue crack growth and superior damage tolerance. In the aerospace industry, the drilling process is widely used among all the machining processes as millions of holes are required to produce riveted and bolted joints in the assembly operation of the aircraft's structures. The major challenges which arise from the drilling of these alloys are characterized by the low hole quality, which might initiate cracks within the airframe structure and reducing their reliability. This results in the rejection of parts at the assembly stage, which directly impacts the manufacturing cost. Hence, an appropriate selection of tool geometry, tool materials and coatings, cutting speed, feed rate, and drilling machines is required to meet the requirements of machined parts. The large number of holes required for riveting means that their installation must be carried out in a fast and precise manner. This can be achieved by using multi-head drilling tools that can drill several holes simultaneously. Therefore, in this study, a simultaneous multi-hole drilling approach was used to investigate the important drilling output parameters, such as the thrust force, chips formation, post-drilling tool conditions and hole metrics including surface roughness, deviation of hole from the nominal size, circularity, cylindricity, perpendicularity, and burrs formation under dry conditions. Moreover, the inside hole surface defects and top and bottom hole edges were examined using scanning electron microscopy. The investigations were based on different cutting parameters, the maximum and minimum possible center-to-center spindle distances of the multi-spindle head, tool geometry, tool materials and four types of tool coatings (TiN-, TiCN-, TiAlN-, and TiSiN). Furthermore, analysis of variance was employed for estimating the relationships between the input parameters (spindle speed, feed, and tool coating) and the studied hole quality metrics. The focus was mainly on Al2024 alloys, which is commonly used as an aerospace structural material. The results show that uncoated carbide drills with high point angle and smaller diameter generated less thrust force, produced higher quality holes, and formed a lower built-up edge due to short chips. The common surface damage found on the inner hole surface was smearing, feed marks, and metal debris adhesion. The results also show that the uncoated carbide drills performed better at low spindle speeds, while TiCN-coated drills produced better hole quality at higher spindle speeds. Regarding the coated drills, TiCN-coated drills produced holes with the least deviation, circularity, cylindricity and perpendicularity at high spindle speeds. TiSiN-carbide coated drills produced the most oversized holes and noticeable damage and deformations on their surface following TiAlN and TiN. Besides, tools of the multi-spindle head can be adjusted in any position without affecting the hole quality, which is useful for increasing productivity at a higher rate in manufacturing industries.
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Niu, Zhichao. "Investigation on the multiscale multiphysics based approach to modelling and analysis of precision machining of metal matrix composites (MMCs) and its application perspectives." Thesis, Brunel University, 2018. http://bura.brunel.ac.uk/handle/2438/17549.
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Over the last two decades or so, metal matrix composites (MMCs) have been drawing the attention of the industry due to their potentials in fulfilling demands for high performance industrial materials, products and advanced engineering applications. On the other hand, the high precision machining is becoming one of the most effective methods for enabling these difficult-to-machine composites to be applied particularly in precision engineering. Therefore, in-depth scientific understanding of MMC precision machining is essential and much needed so as to fulfil the gap between fundamental issues in precision machining of MMCs and their industrial scale applications. This thesis focuses on development of a multiscale multiphysics based approach to investigating the machinability of particulate MMCs and the machining process optimisation. In order to investigate the surface generation in relation to the process variables, this PhD study covers the key fundamental issues including chip formation process, dynamic cutting force, cutting temperature partition and tool wear by means of combining modelling, simulation and experimental study. The chip formation mechanisms and the minimum chip thickness in precision machining of SiCp/Al and B4Cp/Al MMCs by using PCD tools are investigated through a holistic approach. Minimum chip thickness (MCT) value is firstly identified based on the modified mathematical model. The certain threshold of the uncut chip thickness, i.e. chips starting to form at this chip thickness point, is then established. The chip formation process including the matrix material breakage, particles fracture, debonding, sliding or removal and their interfacial interactions are further simulated using finite element analysis (FEA). The minimum chip thickness and chip formation simulations are evaluated and validated via well-designed experimental trials on a diamond turning machine. The chips and surface profiles formed under varied process variables in periodic material removals are inspected and measured in order to obtain a better understanding on MMC chip formation mechanisms. The improved dynamic cutting force model is developed based on the micro cutting mechanics involving the size effect, undeformed chip thickness effects and the influence of cutting parameters in the micro scale. Cutting process variables, particle form, size and volume fraction at different scales are taken into account in the modelling. The cutting force multiscale modelling is proposed to have a better understanding on the MMCs cutting mechanics and to predict the cutting force accurately. The cutting forces are modelled and analysed in three cutting regimes: elastic recovery zone, ploughing zone and shearing zone. A novel instantaneous chip thickness algorithm including real chip thickness and real tool trajectory is developed by taking account of the tool runout. Well-designed cutting trials are carried out under varied process variables to evaluate and validate the force model. In order to obtain the actual cutting forces accurately, transfer function technique is employed to compensate the measured cutting forces. The cutting force model is further applied to correlate the cutting tool wear and the prediction of the machined surface generation. Multiphysics coupled thermal-mechanical-tribological model and FE analysis are developed to investigate the cutting stress, cutting temperature, tool wear and their intrinsic relationships in MMCs precision machining process. Heat generation, heat transfer and cutting temperature partition in workpiece, chips and cutting tool are simulated. A modified tool wear rate model is proposed, tool wear characteristics, wear mechanisms and dominate tool wear are further investigated against the real machining process. Cutting tool wear is monitored and assessed offline after machining experiments. The experimental study on the machined surface generation is presented covering cutting force, tool wear, tool life, surface roughness and machining efficiency. Process optimisation is explored by considering the variation of cutting parameters, cutting tool conditions and workpiece materials in order to achieve the desired outcomes and machinability.
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Saillet, Alan. "Implementace a aplikace metody párování obráběných materiálů a břitů při orbitálním vrtání." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2018. http://www.nusl.cz/ntk/nusl-451199.
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This internship's objective is to implement modeling of uncut chip thicknesses and milling forces in 3-axis milling, and apply it to orbital drilling. The goal is to understand deeper the process, and develop a tool which permits to model a wide range of end-mill tool geometries, and most of 3-axis milling operations.In this report, the following axis will be developed: • The modeling of the complex tool geometry • The modeling of uncut chip thicknesses in slot milling, and for any 3-axis milling operation • The strategy which has been chosen to identify cutting forces coefficients, and their use. • The obtained results and prospects for development.
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Miah, Farid. "Numerical and experimental analysis of CFRP machining process in orthogonal cutting." Thesis, Toulouse 3, 2020. http://www.theses.fr/2020TOU30005.
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Les matériaux composites, y compris le PRFC (polymère renforcé de fibre de carbone), sont de plus en plus utilisés en aéronautique et dans l'automobile, ce qui soulève actuellement de nombreuses complications dans les processus d'usinage. Comme ces matériaux sont fabriqués en plusieurs phases, ils sont responsables d'une mauvaise qualité d'usinage et de défauts indésirables. Cette thèse vise à mieux comprendre la technique physique fondamentale impliquée dans le mécanisme de formation de copeaux dans le découpage orthogonal d'usinage en PRFC par des études numériques et expérimentales combinées. Ensuite, l'analyse se concentre sur la manière dont certains paramètres de coupe, par exemple, la profondeur de coupe, affectent les efforts de coupe, la qualité de surface, les délaminations entre couches, la génération de fissures internes et la forme et la taille de copeaux générées. De plus, une observation expérimentale a été faite pour déterminer la profondeur de coupe minimale en dessous de laquelle le matériau ne peut pas être coupé en douceur sur toute la surface. Ce travail de recherche a été complété par une étude préliminaire sur le mécanisme d'usure des outils de coupeThe composite materials, including CFRP (Carbon Fiber Reinforced Polymer), are increasingly used in aeronautics and automotives which is currently raising many complications in the machining processes. As those materials are made with multiple phases, they are accountable for poor machining quality and undesired defects. This thesis seeks to better understand the fundamental physical technique involved in chip formation mechanism in orthogonal cutting of CFRP machining by combined numerical and experimental studies. Then, the analysis focuses to how certain cutting parameters, e.g., cutting depth, affect to the cutting efforts, surface quality, interply delaminations, inner crack generation and to generated chip shape and size. Moreover, an experimental observation has been made to find out the minimum cuttable depth below which the material does not get cut smoothly over the whole surface. This research work has been finished by a preliminary study on cutting tool wear mechanism
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Espanhol, Victor. "Análise dos esforços de corte e acabamento superficial no torneamento de aço com ferramenta de superfície lisa e com quebra-cavaco." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2008. http://hdl.handle.net/10183/14374.
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Este trabalho apresenta resultados de testes com processo de usinagem para diferentes ferramentas de torneamento. Foram realizados ensaios para avaliar a diferença de comportamento quantoa esforçosde cortee acabamentosuperficialem operaçãode torneamento para um mesmo tipo de ferramenta, com variação na superfície de saída, sendo uma com quebra cavaco com outra de superfície de saída lisa. O material usinado foi aço ao carbono 1045 recozido, testado para duas diferentes velocidades, variando-se também a profundidade de corte e avanço para cada ensaio. Os testes foram executados em um torno mecânico convencional, onde as variáveis do processo foram coletadas com um sistema de aquisição de dados, através de um dinamômetro piezoelétrico para avaliação das forças de corte e um rugosímetro portátil para medida da rugas idade superficial. Observou-se nos resultados, uma forte diminuição dos esforços quando aplicada a ferramenta sinuosa com quebra-cavaco, bem como melhoria nas características do cavaco. Em relação à rugas idade superficial houve uma pequena melhora quando utilizada a ferramenta com superfície de saída lisa, situação decorrente das condições de remoção do cavaco.This wark presents the results af machiningpracess tests with different turning tools. Tests were done to evaluate behaviors differenceson cutting efforts and surface finishing in turning operations to a same type of tool, with a variation on rake face, where one had a chipbreaker groove and the other are flat. The machining material was 1045 annealed carbon steel, tested to two different cutting speeds, changing also the depth of cut and the feed rate for each case. The tests were done in a conventionallathe, where the process variances were collected by a data acquisition system, through a piezoelectric dynamometer to evaluate the cut efforts and a portable rugosimeter to measure the surface roughness. The results show a strong reduction of the efforts when grooved tools with chip-breaker were applied as well an improvement on the chip characteristics. In relation to the surface roughness, it was observed a slight improvement when the tlat tool was used, because ofthe conditions of chip remova!.
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Liu, Jian. "Experimental study and modeling of mechanical micro-machining of particle reinforced heterogeneous materials." Doctoral diss., University of Central Florida, 2012. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5408.
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This study focuses on developing explicit analytical and numerical process models for mechanical micro-machining of heterogeneous materials. These models are used to select suitable process parameters for preparing and micro-machining of these advanced materials. The material system studied in this research is Magnesium Metal Matrix Composites (Mg-MMCs) reinforced with nano-sized and micro-sized silicon carbide (SiC) particles. This research is motivated by increasing demands of miniaturized components with high mechanical performance in various industries. Mg-MMCs become one of the best candidates due to its light weight, high strength, and high creep/wear resistance. However, the improved strength and abrasive nature of the reinforcements bring great challenges for the subsequent micro-machining process. Systematic experimental investigations on the machinability of Mg-MMCs reinforced with SiC nano-particles have been conducted. The nanocomposites containing 5 Vol.%, 10 Vol.% and 15 Vol.% reinforcements, as well as pure magnesium, are studied by using the Design of Experiment (DOE) method. Cutting forces, surface morphology and surface roughness are characterized to understand the machinability of the four materials. Based on response surface methodology (RSM) design, experimental models and related contour plots have been developed to build a connection between different materials properties and cutting parameters. Those models can be used to predict the cutting force, the surface roughness, and then optimize the machining process. An analytical cutting force model has been developed to predict cutting forces of Mg-MMCs reinforced with nano-sized SiC particles in the micro-milling process. This model is different from previous ones by encompassing the behaviors of reinforcement nanoparticles in three cutting scenarios, i.e., shearing, ploughing and elastic recovery. By using the enhanced yield strength in the cutting force model, three major strengthening factors are incorporated, including load-bearing effect, enhanced dislocation density strengthening effect and Orowan strengthening effect. In this way, the particle size and volume fraction, as significant factors affecting the cutting forces, are explicitly considered. In order to validate the model, various cutting conditions using different size end mills (100 &"181;m and 1 mm dia.) have been conducted on Mg-MMCs with volume fraction from 0 (pure magnesium) to 15 Vol.%. The simulated cutting forces show a good agreement with the experimental data. The proposed model can predict the major force amplitude variations and force profile changes as functions of the nanoparticles' volume fraction. Next, a systematic evaluation of six ductile fracture models has been conducted to identify the most suitable fracture criterion for micro-scale cutting simulations. The evaluated fracture models include constant fracture strain, Johnson-Cook, Johnson-Cook coupling criterion, Wilkins, modified Cockcroft-Latham, and Bao-Wierzbicki fracture criterion. By means of a user material subroutine (VUMAT), these fracture models are implemented into a Finite Element (FE) orthogonal cutting model in ABAQUS/Explicit platform. The local parameters (stress, strain, fracture factor, velocity fields) and global variables (chip morphology, cutting forces, temperature, shear angle, and machined surface integrity) are evaluated. Results indicate that by coupling with the damage evolution, the capability of Johnson-Cook and Bao-Wierzbicki can be further extended to predict accurate chip morphology. Bao-Wierzbiki-based coupling model provides the best simulation results in this study. The micro-cutting performance of MMCs materials has also been studied by using FE modeling method. A 2-D FE micro-cutting model has been constructed. Firstly, homogenized material properties are employed to evaluate the effect of particles' volume fraction. Secondly, micro-structures of the two-phase material are modeled in FE cutting models. The effects of the existing micro-sized and nano-sized ceramic particles on micro-cutting performance are carefully evaluated in two case studies. Results show that by using the homogenized material properties based on Johnson-Cook plasticity and fracture model with damage evolution, the micro-cutting performance of nano-reinforced Mg-MMCs can be predicted. Crack generation for SiC particle reinforced MMCs is different from their homogeneous counterparts; the effect of micro-sized particles is different from the one of nano-sized particles. In summary, through this research, a better understanding of the unique cutting mechanism for particle reinforced heterogeneous materials has been obtained. The effect of reinforcements on micro-cutting performance is obtained, which will help material engineers tailor suitable material properties for special mechanical design, associated manufacturing method and application needs. Moreover, the proposed analytical and numerical models provide a guideline to optimize process parameters for preparing and micro-machining of heterogeneous MMCs materials. This will eventually facilitate the automation of MMCs' machining process and realize high-efficiency, high-quality, and low-cost manufacturing of composite materials.Ph.D.
Doctorate
Mechanical and Aerospace Engineering
Engineering and Computer Science
Mechanical Engineering
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Santaniello, Tommaso. "Hybrid microfluidic devices based on polymeric materials functionalized for cell biology applications." Thesis, Loughborough University, 2014. https://dspace.lboro.ac.uk/2134/14933.
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The present thesis work deals with the development of a novel manufacturing protocol for the realization of excimer laser micro-patterned freestanding hydrogel layers (50 to 300 ??m thickness) based on thermo-responsive poly-(N-isopropyl)acrylamide (PNIPAAm) which can operate as temperature-triggered actuators for cells-on-chip applications. PNIPAAm based thin films were synthesized in house and manufactured by an injection/compression moulding based technique in order to obtain flat hydrogels attached to rigid polyvinyl chloride (PVC) substrates to facilitate laser focusing. Laser machining parameters were empirically optimized to fabricate arrays of through-holes with entrance diameter ranging from 30 ??m to 150 ??m and having different exit diameter (from 10 to 20 ??m) on the PNIPAAm employing a stencil aluminum mask. After laser processing, the microstructured layers were detached from the PVC using a chemical treatment and then left to swoll in pure water. The KrF excimer laser machined through-holes could be reversibly modulated in terms of size as a consequence of the polymer volumetric phase transition induced by a temperature change above the critical value of 32 ??C. Thermo-responsiveness characterization was carried out on the detached water swollen freestanding layers using a thermostat bath, by changing the temperature from 18 ??C to 39 ??C and each sample could undergo multiple cycles. As a result of the polymer water loss, the shrinkage of the layer caused the holes to shrink homogeneously, thus reducing their original size of about the 50% in the polymer collapsed state. To prove the functionality of these stimuli-responsive smart surfaces in the frame of cells-on-chip systems, they were integrated in a multilayer microfluidic device to operate as self-regulating cell sorting actuators for single cell assays applications. Using mechanical fastening as the packaging strategy, the hydrated hydrogel was sealed between two micro-milled poly-methyl methacrylate (PMMA) components, which provided the fluid accesses and ducts to the cell suspension to be flown over the thermoresponsive actuator (top layer) and the well to collect the sorted sample (bottom layer). The device is also equipped with a thin transparent heater to control the microfluidic chip temperature. When the system is assembled, the temperature-triggered actuation mechanism was exploited to trap a cellular sample in the shrunken exit hole on the top of the hydrogel layer by applying a negative pressure across the film via the bottom PMMA component when the system is kept at 37 ??C. Subsequently, the sorting of the trapped cell took place through the micro-capillary when the polymer natural relaxation at room temperature towards its initial state occurred; the operational principle of the device was proved using MG63 cells as a model cell line by monitoring the sorting through the size-modulating structures using optical microscopy.
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Hon, Pavel. "Třískové hospodářství obráběcího stroje." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2011. http://www.nusl.cz/ntk/nusl-229433.
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This project is devided to three parts - theoretical overview of cutting farm components, design of cutting farm for specified production cell and the design of chip conveyor for specified cuting machine. Theoretical overview introduces common commercial used components of cutting farm, their properties and using possibilities in particular regarding their applicability at cutting farm design and chip conveyor design. In the second part there is proposal of design of cutting farm for production cell consist of six identical multi-function machinig centers. For produced amount of chips there is proposal of their processing from the begining at cuting proccess up to their leavig production hall as a briquetts in a containers. At last part of this project there is complete design proposal of chip conveyor for mentioned multi-function maching center. Design is built from a basic line diagram up to design of particular components including calculations and analysis.
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Wolf, Jason. "INVESTIGATION OF CHIP-FORM AND TOOL-WEAR IN TURNING OF HARDENED AF9628 ALLOY UNDER VARIOUS COOLING AND LUBRICATION CONDITIONS." UKnowledge, 2019. https://uknowledge.uky.edu/ms_etds/10.
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Next generation defense and commercial applications for structural steels require new alloys that eliminate or reduce critical elements from their composition to lower cost and improve manufacturability, while maintaining or exceeding high strength and toughness requirements. A new alloy, denoted as AF9628, has recently been developed for this purpose and its manufacturing characteristics and the material response in component manufacturing must be fully understood.
In the present study, hardened AF9628 alloy was turned with a coated carbide cutting tool under fixed cutting speed, feed rate, and depth of cut parameters. This work focuses on chip-form and tool-wear analysis to understand, for the first time with AF9628, these fundamental aspects of the turning process and their relationship to productivity and part quality. Current industry standard practice of flood-cooled machining for AF9628 was used during machining experiments. Dry, minimum quantity lubrication (MQL), and cryogenic machining were investigated as alternative cooling and lubrication conditions.
High-speed imaging during AF9628 turning experiments provides a new insight into the chip formation process, while the use of optical microscopy and scanning white light interferometry allowed for further characterization of chip-form and tool-wear. Chip-form is favorable as short, arc-shaped chips with new tools under all of the tested cooling and lubrication conditions. As a result of rapid wear at the end of the tool-life in all of the experimental conditions, chip-form evolves to unfavorably long, snarled ribbon-like chips and the resultant cutting force increased by as much as 64% under flood-cooled conditions.
Tool-wear types that were observed during experiments include a combination of nose wear, built-up edge, plastic deformation, and groove wear on the rake face. Due to the fixed cutting parameters and cutting tool selected for this study, which were designed for flood-cooled machining in a prior study, undesirable failure of the cutting tools under dry, MQL, and cryogenic machining occurred. Future work requires experimentation across a wider processing space, and with different cutting tools, to thoroughly evaluate alternative cooling and lubrication techniques for machining AF9628.
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Zvěřina, Martin. "Výpočtová simulace procesu třískového obrábění." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2010. http://www.nusl.cz/ntk/nusl-229040.
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This Master’s thesis process list of different finite element programs, which allows us to simulate process of material separation. We estimated their advantages and disadvantages in the end. In program ANSYS Ls-Dyna was created 3D model, in which we simulate process of orthogonal splinter machining and we study dependence of changes different input parameters (tool geometry, depth of cut, cutting speed) on the chip form and forces rate between tool and workpiece.
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Szlaur, Vít. "Analýza procesů obrábění kovových materiálů se zaměřením na energetické aspekty." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2012. http://www.nusl.cz/ntk/nusl-230098.
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A general analysis of machining problems, analysis of cutting forces for turning, milling, drilling. Evaluation of experimentally measured values of surface structure and theoretical values of cutting forces in turning cylindrical parts. Economical processes for the comparable results of the final state of the surface.
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Hradil, Roman. "Návrh technologie výroby vybrané součásti v systému regulace parní turbíny." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2017. http://www.nusl.cz/ntk/nusl-318648.
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The subject of this thesis is the design of production technology of the hydraulic cylinder – the part of servomotor of a steam turbine control valve. The main precondition is a perspective technology of manufacturing the component on a single workplace using Siemens NX10 CAM system. The implementation of this work was carried out in cooperation with the Siemen, s.r.o., the branch of Industrial Turbomachinery in Brno. Part of the thesis is a brief introduction to the issue of steam turbines. The main part is devoted to analysis of a selected component in terms of technology, design of the best strategy of production technology and its implementation. The conclusion deals with the technical and economic assessment of the proposal.
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Грущак, Роман Богданович, and Roman Hrushchak. "Дослідження силових факторів при багато різцевому точінні з гарантованим подрібненням зливної стружки." Master's thesis, Тернопільський національний технічний університет імені Івана Пулюя, 2018. http://elartu.tntu.edu.ua/handle/lib/26760.
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Роботу виконано на кафедрі конструювання верстатів, інструментів та машин Тернопільського національного технічного університету імені Івана Пулюя Міністерства освіти і науки УкраїниУ дипломній роботі магістра розглянуті результати досліджень силових факторів, які виникають при багатолезовому точінні, що супроводжується гарантованим подрібненням зливної стружки. Дослідження проведені на прикладі двох різцевої обробки. Метою роботи є підвищення точності і продуктивності обробки при використанні такого багатолезового оснащення. При цьому розроблена класифікація основних видів подрібнення зливної стружки, визначені характеристики зміни силових факторів в процесі багато різцевого точіння, а також проведена порівняльна оцінка зміни осьових складових сил різання при багатолезовому і традиційному точінні на прикладі двох різцевої обробки. Розроблені схеми гарантованого подрібнення зливної стружки при використанні двохрізцевого оснащення. На основі технологічних розрахунків і побудови схем формоутворення визначена базова компоновка токарного верстату, а також розроблена коробка швидкостей і пристосування. Конструкторсько-технологічні розробки супроводжуються техніко-економічним обґрунтування інженерних рішень та комп’ютерними розрахунками. В дипломній роботі розроблені необхідні заходи з охорони праці, безпеки життєдіяльності та екології.
The Master Diploma Paper deals with investigation results of power factors taking place in multi-edge turning following with guarantied continuous metal chip breaking. The research was conducted according to the double-edge machining example. The investigation goal lies in machining accuracy and productivity increasing when such multi-edge accessories using. In this way the main kinds classification of continuous chip breaking as well as the power factor characteristics in the process of multi-edge turning were developed. The comparing estimation of cutting forces axial components changing was performed according to the cases of multi-edge and traditional machining exemplifying the double-edge accessories. The constructive schemes of guarantied continuous metal chip breaking devices using double-edge accessories were developed. Taking into account the technological calculations and shape forming diagrams the base design structure of the engine lathe was determined and in this way the designs of the speed box and corresponding accessories were developed. The design and technological work is followed with the technical and economic discussion of engineering decisions and IT calculations. The diploma paper also deals with development of the necessary labor protection and life safety measures as well as decisions meeting the ecology requirements.
Вступ; Перший розділ "АНАЛІТИЧНИЙ"; Другий розділ "ОПТИМІЗАЦІЯ СХЕМ ФОРМОУТВОРЕННЯ НА ПРОЕКТОВАНОМУ ВЕРСТАТІ І ОПТИМІЗАЦІЯ ЙОГО КОМПОНУВАЛЬНОЇ СХЕМИ ";Третій розділ " ВИБІР ТА ОБГРУНТУВАННЯ ВИХІДНИХ ДАНИХ НА РОЗРОБКУ ВЕРСТАТНОГО ОБЛАДНАННЯ " ;Четвертий розділ "ПРОЕКТУВАННЯ КОНСТРУКЦІЇ ВЕРСТАНОГО ОБЛАДНАННЯ"; П'ятий розділ "НАУКОВО-ДОСЛІДНИЙ" ;Шостий розділ "СПЕЦІАЛЬНИЙ"; Сьомий розділ "Техніко-економічне обґрунтування"; Восьмий розділ "ОХОРОНА ПРАЦІ" ; Дев’ятий розділ "БЕЗПЕКА В НАДЗВИЧАЙНИХ СИТУАЦІЯХ"; Десятий розділ " ЕКОЛОГІЯ" ; Висновки; Перелік посилань; Додатки.
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Silva, Márcio Aurélio da. "Investigação experimental da formação do cavaco na usinagem do aço ABNT 1045 e do ferro fundido nodular." Universidade Federal de Uberlândia, 2008. https://repositorio.ufu.br/handle/123456789/14813.
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Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorThe chip formation is influenced by several cut parameters which also affect the forces, tensions, powers and temperatures generated during the machining process. Although they have been studied for more than 100 years, still today, the involved mechanisms of deformation are not totally know, due to the fact that the chip formation involves high temperatures and high levels of deformation. This research aims at studying the basic process of chip formation, as well as the influence of the main cut parameters such as cutting speed, feed rate, cutting fluid, tool coating and machined material, besides determining the force of residual cut for ABNT 1045 steel. The inquiry was based on the classification of the chips concerning their type and form, thicknesses values, shear angles, stresses degree and in the monitoring of the cutting forces. Micrographs and measurement of the chips microhardness were made in order to achieve a detailed structural analysis. The results found have shown that the parameters and analyzed conditions really influenced the formation of the chips, being the feed rate more significant than the cutting speed. The tool coating and the cutting fluid had a great influence on the chip formation as well as on the cutting forces during the machining of ABNT 1045 steel and nodular casting iron. The residual cutting force for the ABNT 1045 steel varied between 45 N and 52N.
A formação do cavaco é influenciada por vários parâmetros de corte que afetam também as forças, tensões, potências e temperaturas geradas durante a usinagem. Apesar de ser estudado a mais de 100 anos, ainda hoje os mecanismos de deformação envolvidos não são totalmente conhecidos. Isto se deve ao fato da formação do cavaco envolver grandes temperaturas e altíssimas taxas de deformação. Este trabalho pretende estudar o processo básico de formação do cavaco bem como a influência dos principais parâmetros de corte, tais como velocidade de corte, avanço, fluído de corte , revestimento da ferramenta e material usinado, além de determinar a força de corte residual para o aço ABNT 1045. A investigação foi baseada na classificação dos cavacos quanto ao seu tipo e forma, valores das espessuras, dos ângulos de cisalhamento, grau de recalque e no monitoramento das forças de corte. Foram feitas micrografias e medição da microdureza dos cavacos para uma análise estrutural mais detalhada. Os resultados encontrados através dos experimentos mostraram que os parâmetros e condições analisadas realmente influenciam na formação dos cavacos, sendo que o avanço foi mais significativo que a velocidade. O revestimento e o fluído tiveram grande influência tanto na formação do cavaco como nas forças de corte durante a usinagem do aço ABNT 1045 e do ferro fundido nodular. A força de corte residual para o aço ABNT 1045 variou entre 45 N e 52N.
Mestre em Engenharia Mecânica
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Erkers, Louise. "Chemical Interactions between tool and Aluminium alloys in metal cutting." Thesis, KTH, Materialvetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-291358.
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Aluminium applications in automotive will increase by 25 % over the next decade, mainly driven by the electrification and the reduction of fuel consumption. This diploma work aims to increase the understanding of the chemical interactions between aluminium alloys and typical tool systems in metal cutting. First the temperature at the tool-chip interface was estimated by FEM simulations, using the software AdvantEdge. Thereafter the chemical interaction of the tool-chip interface was calculated at the simulated temperature using the Thermo-Calc software. The thermodynamic data and descriptions of the multicomponent systems used where found in the literature, assessed by other authors, but critically reviewed for the use in this work. The results of the FEM simulations indicate that the temperature for machining aluminium with PCD and cemented carbide is between 60-80 % of the melting temperature of Al7wt %Si alloy. The calculations of the chemical interaction in turn results in that several hard precipitates can stick to or transform on the surface of the workpiece or tool-chip interface, for example SiC, Al4C3 and evidently diamond from the tool. This work concluded that more predictive modelling is needed to refine the results and the results from this work needs to be confirmed with experiments. The results show that the modelling can predict the reaction phases at the tool-chip interface, this can be used as input for the tool wear mechanisms during development of tooling solutions.Aluminium användningen inom fordonsindustrin förväntas öka med 25 % under det närmsta decenniet, främst på grund av elektrifiering men också för att för att minska bränsleförbrukning. Målet med detta examensarbete är till att öka förståelsen för de kemiska interaktionerna mellan aluminiumlegeringar och typiska verktygssystem vid metallskärning, framförallt vid bearbetning av aluminiumlegeringar innehållande kisel med ett TiN-belagt PCD-verktyg och icke-belagda verktyg. Detta gjordes genom prediktiva FEM-simuleringar av temperatur, med hjälp av mjukvaran AdvantEdge. Parallellt med detta skapades databaser för simulering av den kemiska interaktionen mellan skär och bearbetningsmaterial i programvaran Thermo-Calc. De termodynamiska data och beskrivningarna av de termodynamiska system som används var bedömda av andra författare men kritiskt granskade för användning i detta arbete. Resultaten av FEM-simuleringarna gav den beräknade temperaturen för bearbetning av aluminium med PCD ligger någonstans mellan 60-80 % av smälttemperaturen för Al7wt % Si-legering. Beräkningarna av den kemiska interaktionen resulterar i sin tur i att flera hårda utskiljningar kan fastna på eller transformera på ytan mellan arbetsstycket och verktyget, till exempel SiC, Al4C3och diamant från verktyget. Resultaten från detta arbete visar att det går att förutsäga fasomvandlingar mellan skär och arbetsstycket, samt att detta kan användas som indata för skärförslitning under utvecklingen av verktygslösningar.
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Ladonne, Mathieu. "Modélisation du procédé de perçage assisté par vibrations forcées : prise en compte de l’environnement Pièce-Outil-Machine." Thesis, Paris, ENSAM, 2016. http://www.theses.fr/2016ENAM0006.
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Le perçage assisté par vibrations est un procédé assurant la maîtrise dimensionnelle des copeaux pour gagner en fiabilité sur les opérations de perçage. L’ajout d’une oscillation axiale pilotée en amplitude et en fréquence introduit deux nouveaux paramètres à déterminer en adéquation avec les paramètres conventionnels que sont l’avance et la vitesse de coupe. Le paramétrage d’une telle opération n’est donc pas trivial. Afin de fournir un outil d’optimisation du paramétrage du procédé, une nouvelle modélisation prenant en compte l’environnement « Pièce-Outil-Machine » est proposée. L’intégration de la géométrie de l’outil, des spécificités des interactions entre l’Outil et la Matière, et du comportement dynamique de la Machine permet s’adapter aux conditions de mise en oeuvre du procédé. Une méthode d’identification dissociée des éléments de l’environnement « Pièce-Outil-Machine » permet de caractériser les spécificités de chacun de ces éléments. Cette modélisation est validée par une campagne d’essai. La modèle développé dans ces travaux permet donc de prédire le comportement du procédé en vue d’une optimisation des paramètres opératoiresVibrations assisted drilling is a process which ensures chip shape control in order to increase reliability during drilling operations. The adding of axial oscillation, controlled with amplitude and frequency, introduce two new parameters which must determinate according to the conventional parameters (feed and speed rotation). The optimal setting of vibrations assisted drilling is not obvious. To provide an optimization-tool of the process, a new model which take into account the “Tool-Workpiece-Machine” environment, is proposed. Drill geometry, Tool-Workpiece interactions and dynamic behavior of the Machine are incorporated in the model. Tis specificity allows adjusting behavior of the process with the case of application. An identification methodology is presented to characterize the environment. Simulation’s results and experimental results are compared to validate the model. This model thus allows predicting process behavior in order to optimize the operational parameters
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Vostřel, Josef. "Technologické, ekonomické a ekologické aspekty obrábění za sucha." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2009. http://www.nusl.cz/ntk/nusl-228551.
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Using of process liquids improves the procedure and results of machining, on the other hand, increases costs and raises some ecological and hygienic issues. In the work there is gradually analyzed mechanism of chip formation, progress and distribution of heat and thermal fields as well as economic and ecological aspects of dry machining and influence of dry machining on durability of tools. In the experimental part there are evaluated data which were measured during the drilling of cylindrical workpiece with regards to progress of workpiece thermal fields while using various kind of tool coating. In the final part there are stated recommendations for practice.
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Irshad, Muhammad Aatif. "The effect of prior austenite grain size on the machinability of a pre-hardened mold steel. : Measurement of average grain size using experimental methods and empirical models." Thesis, Karlstads universitet, Avdelningen för maskin- och materialteknik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-8777.
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The use of pre-hardened mold steels has increased appreciably over the years; more than 80% of the plastic mold steels are used in pre-hardened condition. These steels are delivered to the customer in finished state i.e. there is no need of any post treatment. With hardness around ~40HRC, they have properties such as good polishability, good weldability, corrosion resistance and thermal conductivity. Machinability is a very important parameter in pre-hardened mold steels as it has a direct impact on the cost of the mold. In normal machining operations involving intricate or near net shapes, machining constitutes around 60% of the total mold cost. Efforts are underway to explore every possible way to reduce costs associated with machining and to make production more economical. All the possible parameters which are considered to affect the machinability are being investigated by the researchers. This thesis work focuses on the effect of prior austenite grain size on the machinability of pre-hardened mold steel (Uddeholm Nimax). Austenitizing temperatures and holding times were varied to obtain varying grain sized microstructures in different samples of the same material. As it was difficult to delineate prior-austenite grain boundaries, experimental and empirical methods were employed to obtain reference values. These different grain sized samples were thereafter subjected to machining tests, using two sets of cutting parameters. Maximum flank wear depth=0.2mm was defined for one series of test which were more akin to rough machining, and machining length of 43200mm or maximum wear depth=0.2mm were defined for second series of tests which were similar to finishing machining. The results were obtained after careful quantative and qualitative analysis of cutting tools. The results obtained for Uddeholm Nimax seemed to indicate that larger grain sized material was easier to machine. However, factors such as retained austenite content and work hardening on machined surface, which lead to degradation of machining operations were also taken into consideration. Uddeholm Nimax showed better machinability in large grained samples as retained austenite(less than 2%) content was minimal in the large grained sample. Small grained sample in Uddeholm Nimax had a higher retained austenite (7+2%) which resulted in degradation of machining operation and a lesser cutting tool life.
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Barbosa, Patrícia Alves. "Estudo do comportamento mecânico na usinagem de aços inoxidáveis." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/3/3151/tde-12122014-153825/.
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A usinagem é caracterizada pela grande quantidade de deformação plástica localizada no material devido à formação do cavaco, de forma que existe um compromisso entre o processo de deformação, encruamento e amolecimento, pelo aumento da temperatura, gerando bandas de cisalhamento. A compreensão destas zonas cisalhamento se faz importante, por conter informações que podem ser aplicadas ao aperfeiçoamento das técnicas de usinagem relacionadas à melhoria do processo e a e à busca da inovação em materiais e ferramentas. Nesse contexto, os aços inoxidáveis, que em geral, são caracterizados como materiais de baixa usinabilidade, em consequência do elevado grau de encruamento e baixa condutividade térmica durante a usinagem, podem facilitar investigações da formação do cavaco pós-processo em razão da morfologia segmentada de seus cavacos. Para tanto, o objetivo deste trabalho foi abordar a usinagem sob a ótica da ciência do comportamento mecânico dos materiais através da avaliação das características e propriedades de três classes de aços inoxidáveis com diferentes estruturas cristalianas e microestruturas. A análise foi feita utilizando respostas de deformação, taxa de deformação, tensão, encruamento e temperatura na zona de cisalhamento primária, determinados a partir do monitoramento das forças de usinagem e caracterização do cavaco (morfologia e microestutura) em ensaios de torneamento semi-ortogonal, visando o levantamento e a relação dos parâmetros fundamentais do sistema de corte, que possam ser fatores significativos na modelagem do processo de usinagem. Os resultados mostraram que aços inoxidáveis apresentaram comportamentos distintos na usinagem, mostrando uma grande dependência da estrutura cristaliana, responsável pelos planos de deslizamento preferenciais, contribuindo para uma maior deformação e reduzindo a tensão de cisalhamento, além da difusividade térmica e dureza do material, que foram fortes indicadores da susceptibilidade dos aços inoxidáveis ao cisalhamento adiabático com formação de cavaco contínuo ou segmentado. A resposta à tensão e deformação dos aços inoxidáveis austenítico e duplex mostraram similaridade quando comparados com a classe martensítica. Não foi evidenciada presença de martensita induzida por deformação na usinagem do aço inoxidável austenítico. Por meio do planejamento composto central foi possível gerar modelos empíricos para cada classe de material relacionando as respostas de deformação, taxa de deformação, tensões, encruamento e temperatura na zona de cisalhamento primária com as condições de corte.Machining is characterized by large amount of located plastic strain on material due to chip formation, so that there is a link between strain process, strain hardening, and heat softening, thus generating shear bands. Understanding these shear zones becomes important because it contains information that can be applied to machining technique improvements related to process optimizing, and the materials and tools innovations. In this context, stainless steels are regarded as poor machinability materials, due to high work hardening and low thermal conductivity; however, their segmented chip morphology is helpful for facilitating the post-process chip formation researches. Therefore, the aim was to approach machining from the viewpoint of the mechanical behavior science by comparing three stainless steels grades with dissimilar crystalline structures and microstructures during cutting. Strain, strain rate, stress, strain hardening, and primary shear plane temperature were the output variables analyzed. These output variables were determined from cutting forces monitoring and chip characterization (morphology and microstructure) in semiorthogonal turning tests. The results showed the stainless steels machining behavior was different depending on the lattice structure, which is responsible for preferential slipping planes, contributing to amount of strain and reducing the shear stress. Thermal conductivity and hardness were also strong indicators of stainless steels adiabatic shear susceptibility by continuous or segmented chip formation. The stress and strain response of austenitic and duplex stainless steel grades were similar compared to martensitic grade. Strain-induced martensite formation was not evidenced in austenitic stainless steel machining. Empirical models of strain, strain rate, stress, strain hardening and primary shear plane temperature as a function of cutting conditions were obtained by means of the central composite design.
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Hayajneh, Mohammed. "A generalized approach for mechanics of chip formation in steady-state and dynamic orthogonal metal cutting using a new model of shear zone with parallel boundaries and its validation to cutting-forces prediction in self-piloting machining." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0005/NQ39626.pdf.
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Neumann, Ondřej. "Konstrukce multifunkčního obráběcího centra." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-230950.
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Design of multi-functional machining center The purpose of this diploma thesis is a design of turning table for multi-functional machining center. The first part is the background research of multi-functional machining centers, rotary tables, chip management and brief overview of chosen machining center’s manufacturers. The sphere of using of the designed machine, including parameters of turning table, and its basic parameters are determined on the basis of this research. Afterwards, the variants of turning table drives are drawn up and one variant of calculation and construction is made. Design of clamping desk and chip management of the machine is also made. Above a specified framework of this thesis, simplified machine foundation design and anchoring of machine parts to this basis is performed. The work also includes a 3D model of turning table and substructure. The complete set of constructed machining center was brought into immersion virtual reality environment.
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Ondrášek, Dušan. "Studie ekonomiky technologie obrábění." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2008. http://www.nusl.cz/ntk/nusl-228041.
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The aim of this diploma thesis addresses issues related to obtaining methodology for the production manager´s decision-making process in the field of technology selection, suitable tooling and cutting tools selection for a specific order or particular production plan. Evaluation of the manufacturing process while taking into consideration complexion of process controlling and contexture to the economy of this process. Analysis and evaluation of technological and economical aspects of a manufacturing process of the CNC chip machining in a real environment is targeted on the field of tooling, its selection, purchase, economy and consumption. The process controlling of technology is based on this analysis as well as the formulation of measuring by economic indicators such as economy, productivity, profitability etc. The analysis of important factors and parameters of this process demonstrated an influence on economy of the company. Several model cases have been created from the company records and from the provided research, the output of which became a basic methodology. The output of the analysis indicates possible directions of a management decision making. Thanks to a complex technical-economic view this thesis can serve as a methodological instrument for decision makers in the field of technology and cutting tool selections as well as an economy of production process improvement.
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Atlati, Samir. "Développement d'une nouvelle approche hybride pour la modélisation des échanges thermiques à l'interface outil-copeau : application à l'usinage de l'alliage d'aluminium aéronautique AA2024-T351." Thesis, Université de Lorraine, 2012. http://www.theses.fr/2012LORR0200/document.
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Ce travail de thèse a été réalisé dans le cadre d'une collaboration internationale entre l'Université de Lorraine (France) et l'Université d'Oujda (Maroc). Les travaux réalisés concernent la modélisation de l'usinage par enlèvement de matière. Deux aspects importants de l'usinage ont été abordés : le processus de la formation de copeaux et les échanges thermiques à l'interface outil-copeau. Dans la première partie de la thèse, une modélisation par élément finis (EF) du processus de la coupe a été mise en place. La segmentation des copeaux a été particulièrement analysée grâce à l'introduction d'un nouveau paramètre, le Rapport d'Intensité de Segmentation, permettant de quantifier ce phénomène. Une corrélation entre la réduction de l'effort de coupe et l'intensité de segmentation a été établie. La deuxième partie de la thèse a été consacrée à l'étude des échanges thermiques à l'interface outil-copeau, qui contribuent entre autres à l'usure de l'outil de coupe. Un des points importants de l'étude est la mise en place d'une procédure d'identification hybride (analytique/numérique) permettant d'estimer le flux thermique transmis dans l'outil de coupe et de remonter au coefficient de partage de la chaleur à l'interface outil-copeau pour chaque vitesse de coupe. Avec les valeurs identifiées du coefficient de partage de la chaleur pour chaque vitesse de coupe, une loi d'échange thermique multi-branches a été proposée et ses paramètres identifiés. Cette loi donnant l'évolution du coefficient de partage de la chaleur en fonction de la vitesse de coupe a également été définie en fonction de la vitesse relative de glissement à l'interface outil-copeau dans le but de l'implanter dans un code de calcul EF. L'interface utilisateur VUINTER du code Abaqus/Explicit a été exploitée pour implanter la loi proposée, afin d'appréhender complètement le contact d'un point de vue mécanique et thermique. Il est désormais possible d'implanter via cette interface-utilisateur n'importe quelle autre loi de contact thermomécanique (frottement, coefficient de partage de la chaleur, etc.). L'implantation via la subroutine VUINTER a été validée sur des cas tests d'abord, et puis ensuite en usinage. Les résultats obtenus pour les flux thermiques avec cette nouvelle procédure sont en très bon accord avec les mesures expérimentales pour le couple outil-matière considéré : AA2024-T351/WC-CoThis PhD. thesis is realised in the framework of an international cooperation between the University of Lorraine (France) and the University of Oujda (Morocco). The work done concerns the modelling of machining process by material removal. Two important aspects of machining have been investigated: the chip formation process and the heat exchange at the tool-chip interface. In the first part of the thesis, a FE modelling of the cutting process has been established. Chips segmentation have been particularly analysed using à new parameter (Segmentation Intensity Ratio) allowing the quantification of the phenomenon. A correlation has been established between the cutting force reduction and the chip segmentation intensity. The second part of the thesis has been devoted to the study of heat exchange at the tool-chip interface, among other phenomena that contribute to the tool wear. One important point of the study is the establishment of a hybrid identification procedure (analytical/numerical) to estimate the heat flux transmitted into the cutting tool, and identification of the heat partition coefficient at the contact interface for each cutting speed. With identified values of the heat partition coefficient obtained by varying the cutting speed, a heat exchange multi-branch law has been proposed and parameters of this law have been identified. This law corresponds firstly to the evolution of the heat partition coefficient as a function of the cutting speed. Thereafter, it was defined in term of the relative sliding velocity at the tool-chip contact interface, in order to implement it in a FE code. The user interface VUINTER of Abaqus/Explicit has been used to implement the proposed law, to fully control the mechanical and thermal contact. It is henceforth possible to implement with this user interface any thermomechanical contact (friction, heat partition coefficient, etc.). The implementation via the user subroutine VUINTER was validated first on adequate tests, then on machining. The obtained results for heat fluxes with this new procedure are in good agreement with experimental measurements for the tool-workmaterial couple considered: AA2024-T351/WC-Co
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Aytekin, Kasim. "Characterization of machinability in lead-free brass alloys." Thesis, KTH, Materialvetenskap, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-240107.
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Ny lagstiftning har lagt fokus på den tociska naturen av bly som legeringselement I mässingsprodukter. Vattenförsörjningssystem är av största oro där misstänkt blyläckage från mässingsprodukter hotar människors hälsa, världen över. Denna studie har utförts i syfte att karaktärisera bearbetbarheten av blyfria mässingslegeringar för att förse industrin med nödvändig information och underlätta att ersätta dagens blyade alternativ. Karaktäriseringen har fokuserat på två specifika bearbetningsprocesser, nämligen svarvning och borrning där intresset har legat hos skärkraftsgenerering och spånbildning. Svarvtesterna riktade sig mot att jämföra tre olika legeringar, CW511L, AquaNordicÒ och CW625N. De två förstnämnda är blyfria och CW625N är en medelblyhaltig mässingslegering. Borrtesterna riktade sig mot att karaktärisera vilken effekt borrgeometrier har på skärkraftsgenerering och spånbildning. Huvudfokus lades på inverkan av spånvinkel och borrdiameter. Borrtesterna utfördes endast på AquaNordicÒ. Resultaten har visat att, signifikant högre skärkrafter genereras vid svarvning av blyfria legeringar jämfört med blyfria. Det fanns emellertid ingen signifikant skillnad mellan de båda blyfria legeringarna avseende skärkrafter, medan spånbildning förbättrades för AquaNordicÒ . Borrtesterna har å andra sidan visat att bearbetningen hos den blyfria AquaNordicÒ -legeringen kan förbättras genom att öka på spånvinkeln och minska borrdiameter. Baserat på resultaten från det här avhandlingsarbetet har man dragit slutsatsen att bearbetningen av blyfria mässingslegeringar är tillräckligt bra för att kunna antas av industrin. Förbättring är dock nödvändig för att ersätta de blyeade alternativen helt.Recent legislation has put focus on the toxic nature of lead as an alloying element in brass products. Watersupply systems are of biggest concern where suspected lead leakages from brass products are threatening human health. A comprehensive study has been conducted in order to characterize the machinability of lead-free brass alloys to provide the industry with necessary information to assist a replacement of the leaded alternatives. The characterization has focused on two particular machining processes, namely turning and drilling and has been based on cutting force generation and chip formation. While the turning tests aimed to characterize the machinability by comparing two lead-free alloys (CW511L and AquaNordic®) with a leaded alloy (CW625N), drilling tests aimed to characterize machinability of the lead-free AquaNordic® alloy particularly, with the main focus put on the impact of tool geometry on machinability. The results have shown that significantly higher cutting forces are generated during turning of lead-free alloys as compared to the leaded. There was, however, no significant difference between the two lead-free alloys regarding cutting forces while chip formation is improved for AquaNordic®. Drilling tests have shown that the machinability of the lead-free AquaNordic® alloy can be improved by increasing the tool rake angle and decreasing tool diameter. Based on the results from this thesis work, it has been concluded that the machinability of lead-free brass alloys is sufficiently good to be able to be adopted by the industry. However, improvement is necessary inorder to fulfill the requirement needed to replace the leaded alternatives.
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Zenia, Sofiane. "Modélisation numérique de l’usinage des matériaux composites à matrice polymère et fibres longues de carbone." Thesis, Université de Lorraine, 2017. http://www.theses.fr/2017LORR0126/document.
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La mise en œuvre des matériaux composites, fait souvent appel à des procédés d’usinage conventionnel, comme l’opération de perçage utilisée lors de l’assemblage de structures par rivetage. Ces opérations peuvent générer dans la pièce usinée différents types d’endommagement: arrachement des fibres, rupture de la matrice, délaminage intralaminaire et interlaminaire, dégradation thermique de la matrice, ce qui peut provoquer une baisse des performances mécaniques de la structure. L’objectif de la thèse est de mettre en place un modèle numérique scientifiquement rigoureux pour analyser l’usinage des composites CFRP et prédire les mécanismes d’endommagement induits par l’outil coupant. Ce modèle basé sur une loi constitutive mésomécanique combine l’effet de la chute de rigidité dans le comportement du matériau, la plasticité, l’initiation et l’évolution de l’endommagement durant le processus d’usinage. Ensuite, deux modèles 2D et 3D adoptant un schéma explicite ont été implémentés via la sub-routine VUMAT dans Abaqus. Le délaminage interplis a été pris en considération à l’aide des éléments cohésifs disponibles dans le code ABAQUS/Explicit. Ce travail a permis de reproduire de manière réaliste les opérations de coupe orthogonale et de perçage des composites CFRP en termes de processus de formation du copeau, la prédiction des forces de coupe et celle de l’endommagement induit. Ces études ont montré que l’orientation des fibres et la profondeur de coupe sont les paramètres les plus influents en coupe orthogonale tandis que pour le perçage se sont les vitesses d’avance et la géométrie des outilsThe machining of composite materials is often necessary for material removal operations by cutting tools such as drilling. These operations can generate a lot of damage in the machined workpiece (fiber fracture, matrix craking, intralaminar and interlaminar delamination and thermal degradation of the matrix), which can cause a decrease of mechanical performance of the structure. The PhD thesis objective is to set up a reliable accurate model to analyze the machining of CFRP composites and to predict the different damage modes induced by the cutting tool. This model is based on a mesomechanical constitutive law combining the stiffness degradation concept into the material behavior, the plasticity, the initiation and the evolution of the damage during the machining process. Two 2D and 3D models adopting an explicit scheme were implemented in Abaqus/Explicit analysis code through the user subroutine VUMAT. Furthermore, interlaminar delamination is taken into account using the cohesive elements available in the ABAQUS / Explicit code. This work allowed to realistic numerical simulation of orthogonal cutting and drilling operations of CFRP composites in terms of chip formation process, cutting forces prediction and induced damage. These studies have shown that the fiber orientation and the depth of cut were the most influential parameters in orthogonal cutting while for the drilling process, the feed rate and the tool geometry are the most important parameters
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Rodrigues, Alessandro Roger. "Estudo da geometria de arestas de corte aplicadas em usinagem com altas velocidades de corte." Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/18/18135/tde-03072005-134755/.
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Trata do estudo experimental da energia específica de corte e sua relação com parâmetros de usinagem, características geométricas e tribológicas das ferramentas, e material da peça usinada. Dentre as variáveis investigadas são destaques a profundidade de usinagem, velocidade de corte, raio de ponta, geometria de quebra-cavaco, tipo de revestimento das ferramentas, dureza, microestrutura e composição química do material da peça. Os seguintes materiais foram empregados nos ensaios: aços SAE 1213, 1020, 1045, ASTM H13 recozido e temperado, e liga de alumínio 2024. As medições de energia específica foram realizadas em uma máquina Charpy instrumentada por meio de um dinamômetro piezelétrico e um encoder ótico rotacional. Vários resultados puderam ser comparados aos obtidos em torno e centro de usinagem CNC devidamente instrumentados. Testes na condição HSM foram implementados nas máquinas-ferramentas. Todas as variáveis pesquisadas mostraram exercer influência sobre a energia específica. O aumento da profundidade de usinagem em 2,3 vezes causou diminuição da energia específica em 21%, na usinagem da liga de alumínio 2024. A elevação da velocidade de corte em torno de 70% conduziu a uma queda da energia específica de 24% para o aço SAE 1020. A geometria da ferramenta influiu mais decisivamente na energia específica sob velocidades de corte convencionais que na condição HSM. Pequenas variações na geometria do quebra-cavaco dos insertos causaram diminuição da energia específica de até 29%, para velocidade de corte convencional, e de 14% para HSM, na usinagem do aço H13 temperado. Diversos resultados de energia específica de corte medidos pelo ensaio Charpy proposto por este trabalho apresentaram boa concordância com os valores equivalentes fornecidos pela literatura científicaThis thesis presents an experimental study about the specific cutting energy and its relation with cutting parameters, geometrical and tribological characteristics of tools, and workpiece material. Depth of cut, cutting speed, tool nose radius, chip-breaker geometry, tool coating, hardness, microstructure and chemical composition of the workpiece material are some investigated variables. The following workpiece materials were tested: SAE 1213, 1020, 1045, annealed and tempered ASTM H13 steels, and 2024 aluminum alloy. The specific cutting energy values were measured by using a Charpy machine instrumented through piezoelectric dynamometer and incremental optical encoder. Several results could be compared to ones from instrumented CNC lathe and machining center. Tests under HSM condition were carried out in machine-tools. All researched variables have influence over specific cutting energy. The depth of cut rise in 2.3x caused a decrease of specific cutting energy around 21% when machining 2024 aluminum alloy. The elevation of the cutting speed about 70% leaded to reduction of specific cutting energy around 24% when machining SAE 1020 steel. The tool geometry present more influence on specific cutting energy under conventional cutting speed than at high speed cutting. Small variations of tool chip-breaker geometries caused diminution of the specific cutting energy up to 29% for conventional cutting speed, and 14% on average for HSM condition when machining tempered ASTM H13 steel. Various specific cutting energy results obtained from the Charpy test proposed by this work presented a good concordance with equivalent ones provided by scientific literature
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Prat, David. "Développement et modélisation de stratégies de fraisage 5 axes de finition -Application à l’usinage de veines fermées." Thesis, Paris, ENSAM, 2014. http://www.theses.fr/2014ENAM0043/document.
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La qualité des surfaces des veines fluides fermées des pièces tournantes de turbomachine participe au rendement de la turbomachine. Il est donc essentiel de maîtriser la finition des veines en usinage 5 axes avec une fraise boule. L'alliage de titane Ti6Al4V est l'un des matériaux utilisés et souffre d'une faible usinabilité. Le choix des paramètres de coupe conditionne la qualité de surface et la durée de vie de la fraise. Pour maîtriser le fraisage 5 axes, des méthodes de caractérisation de la coupe sont développées pour des trajectoires linéaire et circulaire. Les diamètres effectifs et l'épaisseur coupée sont à l'origine de plusieurs phénomènes associés à la coupe tels que la vitesse de coupe, la vitesse d'évolution de l'usure d'outil, des modes d'usinage et des efforts de coupe. Des essais font le lien entre les mesures d'efforts de coupe et d'état de surface avec les méthodes de caractérisation de la coupe. Une fois l'usinage 5 axes en fraise boule caractérisé, deux stratégies de finition multiaxes de veines fermées sont développées en gardant constantes la vitesse d'avance du point générateur et l'orientation relative de l'axe de l'outil avec la normale de la surface locale. La stratégie de tréflage se caractérise par une trajectoire continue en courbure. La stratégie de contournage hélicoïdal met en évidence des discontinuités en tangence de la trajectoire. Une méthode de lissage local de trajectoire est alors développée pour assurer un comportement cinématique et dynamique raisonnable de la machineThe surface quality of closed fluid veins rotating parts of turbo machines participates in the machine output. It is therefore essential to control the finishing of veins in 5-axis machining with a ball end mill. The titanium alloy Ti6Al4V is one of the materials used and suffers from a poor machinability. The choice of cutting parameters affects the surface quality and the life of the cutter. In order to control the 5-axis milling, characterization methods of cutting are developed for linear and circular paths. Effective diameters and the uncut chip thickness is responsible for several phenomena associated with the cut such as the cutting speed, the speed of evolution of the tool wear, the milling modes and cutting forces. Tests are the link between measures of cutting forces and surface quality and characterization methods of cutting. Once the 5-axis machining with ball end mill characterized, two strategies of finishing closed veins in multiaxis are developed keeping constant the feed speed of the contact and the relative orientation of the tool axis with the normal the local surface. The plunge milling strategy is characterized by a curvature continuous trajectory. The helical milling strategy reveals tangent discontinuities of the trajectory. A method of local smoothing trajectory is then developed to provide a reasonable kinematics and dynamics behavior of machine
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Trunda, Jiří. "Technologie výroby frézováním na CNC strojích." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2009. http://www.nusl.cz/ntk/nusl-228382.
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Objective graduation theses, is determining and propound optimal alternate manufacturing section servant as base of electron microscope. As a production method is used chippy cutting on numerical controlled machine behind by the help of usage progressive cutting tools. To construction control program was use 3D CAD/CAM system of Solid Vision, Ltd. Corporation. Product working is complete project and procedure on manufacturing section, that is in finish well-founded technoeconomic evaluation.
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Shi, Qi (Alex). "Recycling of titanium alloys from machining chips using equal channel angular pressing." Thesis, Loughborough University, 2015. https://dspace.lboro.ac.uk/2134/19515.
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During the traditional manufacturing route, there are large amount of titanium alloys wasted in the form of machining chips. The conventional recycling methods require high energy consumption and capital cost. Equal channel angular pressing (ECAP), one of the severe plastic deformation techniques, has been developed to recycle the metallic machining chips. The purpose of the PhD work is to realize the ECAP recycling of titanium alloys, in particular Ti-6Al-4V and Ti-15V-3Cr-3Al-3Sn, and investigate the effects of processing parameters on the resultant relative density, microstructure evolution, texture development and microhardness homogeneity. The microstructures of Ti-6Al-4V and Ti-15V-3Cr-3Al-3Sn machining chips obtained from conventional turning (CT) and ultrasonically assisted turning (UAT) were initially investigated. It was found that ultrafine grains were formed in the primary and secondary shear zones. For Ti-6Al-4V chips, the β phase in the shear zones was refined into nano-sized equiaxed grains and aligned up to form banded structures. For Ti-15V-3Cr-3Al-3Sn chips, the nano-crystalline grains were enveloped in the shear zones and have clear boundaries to the surrounding matrix. It was observed that in terms of microstructure, there is no significant difference between CT and UAT chips. Recycling of Ti-6Al-4V machining chips was carried out at moderate temperatures with various back-pressures. For single-pass samples, the relative density was increased with the applied back-pressure and operating temperature. It was found that after multiple passes, near fully dense recycled Ti-6Al-4V can be fabricated. The microstructure observations showed that the nano-sized equiaxed and elongated grains co-existed with relatively coarser lamellar structures which were initially refined after the first pass. In the subsequent passes, the fraction of equiaxed nano-grains increased with the number of passes. The original β phase banded structures were fragmented into individual nano-sized grains randomly distributed within α matrix. The chip boundaries were eliminated and nano-crystalline microstructure region was observed at the chip/chip interface after multiple passes. In the sample processed at 550 °C, < a →+c → > type dislocations were observed and oxide layer at chip/chip interface was detected. The texture evolution was investigated using electron backscatter diffraction. It was found that the recycled samples performed a strong basal texture along the normal to ECAP inclination direction after the first pass. After multiple passes, in addition to the normal to inclination direction, the recycled Ti-6Al-4V exhibits a basal texture towards the transverse direction. Microhardness mapping showed that the average hardness and degree of homogeneity were increased with number of passes, while the imposed back-pressure had little effect on the average value and homogeneity. Recycling of Ti-15V-3Cr-3Al-3Sn machining chips was implemented using similar ECAP conditions. The effects of processing parameters, such as back-pressure, operating temperature and number of passes, on the relative density were similar to those for Ti-6Al-4V. Microstructural characterization showed that equiaxed instead of needle shaped α precipitates formed in the β matrix due to the high dislocation density and sub-grain boundaries introduced during ECAP. In terms of microhardness, the maximum hardness was obtained at the specimen pressed at 450 °C. It was found that the applied back-pressure and number of passes enabled to improve the homogeneity, but had little effect on the average hardness.
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Mahmood, Khalid. "An investigation into laser deposition of machining chips and characteristics of the final clad." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/an-investigation-into-laser-deposition-of-machining-chips-and-characteristics-of-the-final-clad(45daf674-4f3f-487b-b25c-14fab168b5d0).html.
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Laser metal deposition is an additive manufacturing technique to build fully dense structures with a strong metallurgical bonding with the underlying material. Spherical gas-atomised metal powders are principally used as build material which is a costly option and restricts its application on a wide scale. On the other hand, nonspherical particles produced by machining are much cheaper to produce and readily available as waste swarf which should be recycled. The use of machined particles as a viable form of build material for laser direct metal deposition has not been explored previously and is the subject of the investigations reported in this thesis. In the first work, samples of carbon steel machining swarf in three size ranges were laser deposited to build thin walls. The produced walls exhibited fine martensitic microstructure with minimal porosity. As general trends, individual deposition tracks were found to be lower, and wider with an increase of particle size. 50% reduction in hardness was observed when using coarser particle size. This work was extended so as to build U-shaped structures with variable laser power in contrast to the previous work which was done with one set of processing parameter values. The microstructure observed was similar to that of the previous work. However, hardness has found to increase with decrease in laser power. After successful deposition and encouraging results from the process, machining swarf of Inconel 617 was used to produce corrosion resistant layers on a mild steel substrate. A Design of Experiment methodology was used to analyse the relationship between the processing parameters and the coated layer characteristics. The layer thickness and hardness were found to increase with the mass feed rate whilst an increase in laser power produced the opposite result. All layers had a predominantly dendritic microstructure and displayed remarkably higher corrosion resistance than the mild steel sample. The work was expanded to investigate the surface characteristics and corrosion resistance in a harsh corrosive environment, using different pH brine solutions. In this investigation, four layers were produced with two laser power and mass feed rate values. Accounting for all measurements, Inconel 617 swarf built layers provided very good corrosion protection and confirmed the viability of using this method as a low-cost corrosion protection for both mild and harsh environments. Since the investigations authored above were confined to swarf alone, the final chapter examines the comparison of stainless steel 316L thin wall structures produced with swarf and gas-atomised powder using similar processing conditions. The build materials performed similarly, but walls made from swarf were slightly shorter with a coarser microstructure and had poorer corrosion resistance than the powder equivalents.The results of these investigations confirm the feasibility of machining swarf as an alternative viable option. However, further research will help to explore its full potential.
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Silva, Tayná de Fatima Amorim da. "Estudo da síntese de nanopartículas de NaYF4:Yb:Er a partir de circuito microfluídico projetado no IPEN." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/85/85134/tde-07022019-161716/.
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Este trabalho apresenta a síntese de nanopartículas (NPs) de NaYF4 dopadas com íons terras raras a partir de sistemas microfluídicos projetados e desenvolvidos em parceria entre o Laboratório de Crescimento de Cristais e a Central de Processamento de Materiais a Laser no Centro de Laser e Aplicações IPEN. O objetivo foi o estudo de diferentes circuitos microfluídicos usinados a laser para síntese de NPs de fluoretos em geral. Como material teste foi escolhido o NaYF4:Yb3+:Er3+, visando sua obtenção na fase hexagonal com dimensões definidas. Experiências de síntese deste material por co-precipitação, sem uso de surfactantes, foram realizadas para comparação com as sínteses obtidas via microfluídica. Por co-precipitação foram obtidas partículas esféricas, na fase cubica do NaYF4. Foram projetados e fabricados, via usinagem a laser de pulsos ultracurtos em substrato de vidro ótico BK7, três circuitos microfluídicos. Nas experiências de sínteses realizadas nestes chips foram obtidas NPs de NaYF4:Yb3+:Er3+ tanto na fase cubica quanto na fase hexagonal, em diferentes proporções, dependendo dos fluxos de injeção dos precursores no micro reator, da temperatura e da taxa de residência. As NPs obtidas neste trabalho foram caracterizadas através de DRX e analise pelo método de Rietveld, para a identificação das fases do material, MET para definição de forma e tamanho da nanopartículas e MEV para estudo dos microcanais dos chips usinados a lasers. Os melhores resultados foram observados em chips com microcanais da ordem de 400-600μm, pois minimizam o problema de obstrução. Contudo, o controle da temperatura precisa ser otimizado para evitar trincas nos microcircuitos. As NPs obtidas via microfluídica apresentaram distribuição de tamanho na faixa de 5 a 200nm e fases com estrutura hexagonal e cubica. Foi possível obter NPs de fase única cubica, mas o mesmo não ocorreu para fase hexagonal do NaYF4. O presente estudo permitiu definir vários fatores para a obtenção das NPs de NaYF4 via microfluídica e também referente a fabricação, montagem e uso dos chips, porém para obter NPs desse material com controle da dimensão e fases serão necessários estudos complementares.This work presents the synthesis of NaYF4 nanoparticles (NPs), doped with rare earth ions, using microfluidic systems designed and fabricated at IPEN through Crystal Growth Lab and Materials Laser Processing Lab partnership. The aim of this work was the study of different microfluidic chips laser machined for use in fluoride NPs synthesis. The compound NaYF4:Yb3+:Er3+ (Yb 10 mole%; Er 0.5 mole %) was chosen to test the fabricated microfluidic chips aiming the production of NPs with hexagonal structure with defined dimensions. Synthesis experiments by co-precipitation method of this material without any surfactant were performed to compare with microfluidics synthesis. By this method spherical particles, were obtained with the cubic NaYF4 crystalline structure. Three different chips were designed and fabricated, using a femtosecond laser to machine BK7 optical glass substrate. The synthesis experiments with these chips resulted in NaYF4:Yb3+:Er3+ NPs with both cubic and hexagonal crystalline structure, in different proportions, depending of precursors flux rates, temperature and resident time. The obtained materials of all experiments were characterized by X-ray diffraction and Rietveld analysis, to define crystalline structures parameters; transmission microscopy to define shape and size of NPs and scanning electron microscopy to characterize the chips micro channels machined by laser. The best results were observed for chips with channels of 400-600μm, in view of the obstruction decrease in the chips. The NPs obtained with microfluidics presented sizes from 5nm up to 200nm and hexagonal and cubic crystallographic structures. Cubic single phase NPs were obtained, but the same did not happened with the NaYF4 hexagonal phase. The present study allowed establishing many different parameters for NaYF4 NPs synthesis through microfluidics and concerning fabrication, assembly and experimental use of microfluidic chips, however, additional experiments will be necessary to obtain the fluoride NPs with controlled size and shape.
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YANG, MENG-YAO, and 楊孟瑤. "Investigation of Ideal Machining Condition Considering the Chip Geometry." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/57172342843354129034.
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碩士國立中興大學
機械工程學系
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In this paper, the variations of cutting force, surface roughness and chip formiddle-carbon steel during turn machining were investigated.A throw-away toolwas used. The cutting force and surface roughness were measured using tridirectional dynamometer and surface profilemeter, respectively. The chips are collected and examined. The relationship between cutting force and surface roughness versus the cutting condition can be managed through variation of cutting parameters during the machining process. The primary physical parameters governing the cutting process are (1)cutting speed(2)feed rate and (3)depth of cut. The experimental results show that, with increasing cutting speed, continuouschip production occurs. With increasing feed rate, the chip production rate is reduced. When cutting speed and feed rate are changed, the shape of the chipchanges. Depth of cut is not important to the shape of the chip. It was also found that when continuous chips occurs, the cutting force is lower and the machined surface becomes smooth. With higher cutting force and poor surface roughness, the chip rate is reduced. In turning, the production of continuous chips indicates a lower cutting force and a smooth finished surface. Keywords: turning，chip，cutting force，roughness
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Zhang, Yuegang. "Development of chip size monitoring system in deep-hole machining." Thesis, 2002. http://spectrum.library.concordia.ca/1865/1/MQ72925.pdf.
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This investigation concerns with the metal chip size monitoring method in deep-hole machining process. Monitoring and control of the chip size and shape is very important in deep-hole machining because a visual monitoring is obstructed by hidden chip passages. Yet, for the process, any chip size which may result in passages clogging will result in a failure of machining process. In this manufacturing process monitoring system, the three principal components for chip status monitoring have been investigated: the sensing chip concentration, the signal processing, and the classification (decision making). A new sensing system and monitoring method have been investigated and proposed for use. An inductive proximity sensor was selected and used for data acquisition (sensing), and a personal computer utilized for signal processing. As a monitoring method, the expert system of deep-hole machining control has been suggested for decision making based on the sensing system signal. The experimental testing has revealed that the sensing system signal is strong enough to be used for the machine tool control.
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Syed, Kareem. "Finite element simulation of chip segmentation in machining a Ti 6A1-4V alloy." 2004. http://digital.library.okstate.edu/etd/umi-okstate-1107.pdf.
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Qi, Hong Sheng, and B. Mills. "Modelling of the dynamic tool-chip interface in metal cutting." 2003. http://hdl.handle.net/10454/4081.
Full textAbstract:
NoThe formation of tribo-layers during machining is very common phenomena, especially when machining `free machining¿ steels. Several kinds of tribo-layers formed in metal cutting processes have been reported, layers of inclusions from the workpiece, oxide layers due to chemical reaction, plastic deformation layers, material transfer layers (MTLs) or built-up layers (BULs). A new tool¿chip contact model is proposed to explain the tribo-layer phenomena, which considers the nature of the shear strain rate distribution in the secondary deformation zone. A shear strain rate distribution in this zone having a shape similar to that found in the preliminary zone is proposed. A cutting interface (CI) is defined and this interface is at different location to the material boundary of tool and chip (MBTC). This difference is a key factor in the formation of the tribo-layer in the secondary deformation zone. This model can be used in improving tool wear prediction and the estimation of tool life.