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Gekonde, Haron Ogega. "Influence of dynamic behaviour of materials on machinability." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0002/NQ42737.pdf.
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Wedberg, Dan. "Dislocation density based material model applied in FE-simulation of metal cutting." Licentiate thesis, Luleå tekniska universitet, Material- och solidmekanik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-26278.
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Simulation based design enables rapid development of products with increased customer value in terms of accessibility, quality, productivity and profitability. However simulation of metal cutting is complex both in terms of numeric and physics. The work piece material undergoes severe deformations. The material model must therefore be able to accurately predict the deformation behavior for a large range of strain, strain rates (>50000 s-1) and temperatures. There exist a large number of different material models. They can be divided into empirical and physically based models. The far most common model used in simulation of metal cutting is the empirical Johnson-Cook plasticity model, JC model. Physically based models are based on the knowledge of the underlying physical phenomena and are expected to have larger domain of validity. Experimental measurements have been carried out in order to calibrate and validate a physical based material model utilizing dislocation density (DD) as internal variable. Split-Hopkinson tests have been performed in order to characterize the material behavior of SANMAC 316L at high strain rates. The DD model has been calibrated in earlier work by Lindgren et al. based on strain rate up to 10 s-1 and temperatures up to 1300 °C with good agreement over the range of calibration. Same good correspondence was not obtained when the model was extrapolated to high strain rate response curves from the dynamic Split-Hopkinson tests. These results indicate that new deformation mechanisms are entering. Repeating the calibration procedure for the empirical JC model shows that it can only describe the material behavior over a much more limited range. A recalibrated DD model, using varying obstacle strength at different temperatures, was used in simulation of machining. It was implemented in an implicit and an explicit finite element code.Simulation of orthogonal cutting has been performed with JC model and DD model using an updated Lagrangian formulation and an implicit time stepping logic. An isotropic hardening formulation was used in this case. The results showed that the cutting forces were slightly better predicted by the DD model. Largest error was 16 % compared to 20 % by the JC model. The predicted chip morphology was also better with the DD model but far from acceptable. Orthogonal cutting was simulated using an updated Lagrangian formulation with an explicit time integration scheme. In this case were two hardening rules tested, isotropic hardening and a mixed isotropic-kinematic hardening. The later showed an improvement regarding the feed force prediction. A deviation of less than 8% could be noticed except for the feed force at a cutting speed of 100 m/min. The time stepping procedure in combination with the mesh refinement seems to be able to capture the chip segmentation quite well without including damage evolution in the material model.Further works will mainly focus on improving the DD-model by introducing relevant physics for high strain rates.Godkänd; 2010; 20100809 (danwed); LICENTIATSEMINARIUM Ämnesområde: Materialmekanik/Material Mechanics Examinator: Professor Lars-Erik Lindgren, Luleå tekniska universitet Diskutant: Professor Bevis Hutchinson, Swerea KIMAB, Stockholm Tid: Torsdag den 23 september 2010 kl 10.00 Plats: E246, Luleå tekniska universitet
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Okeke, Christopher Igwedinma. "Threading and turning of aerospace materials with coated carbide inserts." Thesis, London South Bank University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.297919.
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The first part of this study involve an evaluation of the performance of TiN and AlZ03 single layer coated cemented carbide tools when threading inclusion modified, 708M40T (En 19T) 817M40T (En 24T) and Jethete steels at high cutting conditions by monitoring tool wear, failure modes, post threading workpiece properties, micro and macro-surface alterations and subsurface microhardness variation of threaded surfaces. Test results show that flank wear was the dominant failure mode, increasing rapidly when machining at the top speed of 225 m min,l due to the high temperature generated which accelerates thermally related wear mechanisms. Tool life, surface finish, hardness variation and component forces during threading were influenced by the geometry of the cutting edge, shape of wear/length of wear along tool nose/cutting edge after threading. Formation of flake-like oxide debris on the worn inserts was found to increase with nickel content in the workpiece material. The Al20) coated carbide inserts with K05 - K20 substrate gave longer tool life, lower cutting forces, better surface finish! damages as well as minimum hardness variation after threading compared with the TiN coated VSX grade with P20-P30 substrates. This can be related to their superior hardness, density, transverse rupture strength as well as the unalloyed WC fine grained substrate (1/lm) in addition to the high hot hardness, excellent chemical stability and low thermal conductivity of the AlZ03 coating at elevated temperatures. A formula for tool rejection was also developed during this study based on the average flank wear (VBb) and growth in thread root (GTR) in order to establish a scientific basis for assessing wear of threading tools. The second part of this study involve single point turning of a nickel base, G263, alloy using rhomboid-shaped PVD coated (TiN/TiCN/TiN, TiAIN and TiZrN) carbide tools at high speed cutting conditions. The worn tool edges revealed adhesion of a compact fin-shaped structure of hardened burrs with saw-tooth edges. The compact structure also formed on the cut surface of the workpiece material. The use of coolant during machining tend to work harden the root of the burr thereby restricting tool entry at the cutting zone leading to the generation of excessive feed force which subjects the tool edge to premature fracture and consequently lower tool life. The serrated/saw-tooth like edges of the burr encourages abrasion wear on the tool flank face and the formation of shallow cavities/lateral cracks where fragments of hardened workpiece material are deposited causing deterioration of the machined surfaces. Tool life was generally influenced by the cutting conditions employed as well as the insert geometry. Increasing cutting conditions (speed, feed and depth of cut) led to chipping of the cutting edge and/or flaking of coating layers as well as notching and fracture of the cutting edge. These failure modes jointly contributed to lowering tool life during machining. The TiN/TiCN/TiN coated KC732 (Tool A) inserts with positive sharp edges gave overall performance at the optimum cutting conditions established under finishing operation. This is followed by the TiN/TiCN/TiN coated KC732 (Tool B), TiAlN coated KC313 (Tool C) and lastly the TiZrN coated KC313 (Tool D) inserts' with razor sharp edges. Under roughing operation, the ranking order of tool performance is the TiZrN coated KC313 (Tool D), TiN/TiCN/TiN coated KC732 (Tool A), TiAlN coated KC313 (Tool C) and lastly the TiN/TiCN/TiN coated KC732 {Tool B). The difference in tool geometry and coating materials contributed to the relative order of tool performance.
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Stjernstoft, Tero. "Machining of Some Difficult-to-Cut Materials with Rotary Cutting Tools." Doctoral thesis, KTH, Production Engineering, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3693.
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Automobile and aero industries have an increasing interestin materials with improved mechanical properties. However, manyof these new materials are classified as difficult-to-cut withconventional tools. It is obvious that tools, cutting processesand cutting models has to be devel-oped parallel to materialsscience. In this thesis rotary cutting tools are tested as analternative toexpensive diamond or cubic bore nitridetools.
Metal matrix composites mostly consist of a light metalalloy (such as aluminium or titanium) reinforced with hard andabrasive ceramic parti-cles or fibres. On machining, thereinforcement results in a high rate of tool wear. This is themain problem for the machining of MMCs. Many factors affect thelife length of a tool, i.e. matrix alloy, type, size andfraction of the reinforcement, heat treatment, cuttingconditions and tool properties.
In tests, the Al-SiC MMC formed a deformation layer duringmilling, probably affected by lack of cooling. The dominatingfactor for tool life was the cutting speed. Water jet or CO2cooling of turning did not provide dramatic increase in toollife. With PCD, cutting speeds up to 2000 m/min were usedwithout machining problems and BUE formation. Tool flank wearwas abrasive and crater wear created an "orange-peel type" wearsurface. PCD inserts did not show the typical increase in flankwear rate at the end of its lifetime.
The use of self-propelled rotary tools seems to be apromising way to increase tool life. No BUE was formed on therotary tool at high cutting data. The measurements indicatethat the rotary tool creates twice as good surface as PCDtools. The longest tool life was gained with an inclinationangle of 10 degrees. Tool costs per component will beapproximately the same, but rotary cutting tool allows higherfeeds and therefore a higher production rate and thus a lowerproduction cost.
The rotary cutting operation might have a potential toincrease productiv-ity in bar peeling. The lack of BUE withrotary cutting gives hope on higher tool life. The test resultsshow that tool wear was 27% lower with rotary cutting tools.Increase of cutting speed from 22 to 44 m/min did not affectcutting forces. This indicates that the cutting speed canincrease without significant change in tool wear rate.
Issues related to rotary cutting like cutting models,cutting processes, standards, tools and models have beendiscussed. A tool wear model with kinetic energy has beendiscussed.
KEYWORDS:Difficult-to-Cut material, Metal MatrixComposite (MMC), Machining, Machinability, Rotary Cutting Tool,Acoustic Emission
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Gerth, Julia Lundberg. "Tribology at the Cutting Edge : A Study of Material Transfer and Damage Mechanisms in Metal Cutting." Doctoral thesis, Uppsala universitet, Tillämpad materialvetenskap, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-183186.
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The vision of this thesis is to improve the metal cutting process, with emphasis on the cutting tool, to enable stable and economical industrial production while using expensive tools such as hobs. The aim is to increase the tribological understanding of the mechanisms operating at a cutting edge and of how these can be controlled using different tool parameters. Such understanding will facilitate the development and implementation of future, tribologically designed, cutting tools. Common wear and failure mechanisms in gear hobbing have been identified and focused studies of the material transferred to the tool, in both metal cutting operations and in simplified tribological tests, have been conducted. Interactions between residual stresses in the tool coating and the shape of the cutting edge have also been studied. It was concluded that tool failure is often initiated via small defects in the coated tool system, and it is necessary to eliminate, or minimize, these defects in order to manufacture more reliable and efficient gear cutting tools. Furthermore, the geometry of a cutting edge should be optimized with the residual stress state in the coating, in mind. The interaction between a compressive stress and the geometry of the cutting edge will affect the stress state at the cutting edge and thus affect the practical toughness and the wear resistance of the coating in that area. An intermittent sliding contact test is presented and shown to be of high relevance for studying the interaction between the tool rake face and the chip in milling. It was also demonstrated that material transfer, that can have large effects on the cutting performance, commences already after very short contact times. The nature of the transfer may differ in different areas on the tool. It may include glassy layers, with accumulations of specific elements from the workpiece, and transfer of steel in more or less oxidized form. Both tool coating material, its surface roughness, and the relative speed between the tool surface and the chip, may influence the extent to which the different transfer will occur.
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Tulis, Tomáš. "Návrh letmých rotačních nůžek." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2018. http://www.nusl.cz/ntk/nusl-382471.
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The aim of this diploma thesis is to design flying rotary shears for metal cutting at high speed. The shears are a part of a rolling mill where they are used to cut faces and ends of the simple sections, i.e. rounds or squares. In case of the malfunction of the rolling mill, the shears can be used for scrapping the simple sections. A technical report with function destription of the machine as well as machine design according to specified parameters and control calculations are an integral part of the thesis. The required design documentation is included.
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Shi, Bin 1966. "Identification of the material constitutive equation for simulation of the metal cutting process." Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=115709.
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This study presents a novel methodology to characterize material plastic behavior within a practical range of stresses, strains, strain rates, and temperatures encountered in the metal cutting process. The methodology is based on integrating a newly developed analytical model with quasi-static tests and orthogonal cutting experiments that incorporate a laser heating system. Friction and heat transfer models are developed to describe the tribological and thermal interactions at the tool-chip interface. These models are implemented in a FEM package in order to improve the accuracy of the simulation of the machining process.The new analytical model, which is developed to predict the distributions of the stress, the strain, the strain rate, and the temperature in the primary shear zone, is based on conceptual considerations, as well as characterization of the plastic deformation process through comprehensive FEM simulations.
Orthogonal cutting experiments at room temperature and preheated conditions were carefully designed. While the cutting tests at room temperature provided the constitutive data encountered in the primary shear zone, the preheated cutting tests were designed to capture the material behavior at the high level of temperature and strain encountered in the secondary shear zone. In these preheated cutting tests, a laser beam was employed. Quasi-static tests were also utilized to identify some of the coefficients in the constitutive equations, in order to improve the convergence to a unique solution for the constitutive law.
Evaluation criteria were developed to assess the performance of constitutive equations. Based on the developed methodology and the evaluation criteria, a new constitutive equation for Inconel 718 has been proposed. This constitutive equation was further validated by Split Hopkinson Pressure Bar (SHPB) tests and cutting tests in conjunction with FEM simulations. The SHPB test data show an excellent agreement with the proposed material model. The cutting tests and the FEM simulation results also proved the validity of the proposed material constitutive law.
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Oosthuizen, G. A. "Innovative cutting materials for finish shoulder milling Ti-6A1-4V aero-engine alloys." Thesis, Stellenbosch : University of Stellenbosch, 2009. http://hdl.handle.net/10019.1/1561.
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Thesis (MScEng (Industrial Engineering))--University of Stellenbosch, 2009.The titanium alloys have found wide application in the aerospace, biomedical and automotive industries. Soaring fuel prices and environmental concerns are the fundamental drivers that intensify the demand situation for titanium. From a machining viewpoint, one of the challenges companies face, is achieving high material removal rates while maintaining the form and function of the part. The ultimate aim for a machining business remains to make parts quickly. Conventional cutting speeds range from 30 to 100 m/min in the machining of Ti-6Al-4V. Milling this alloy faster however is challenging. Although titanium is becoming a material of choice, many of the same qualities that enhance titanium‟s appeal for most applications also contribute to its being one of the most difficult materials to machine. The author explored the potential for Polycrystalline diamond (PCD) inserts in high speed milling of Ti-6Al-4V, by trying to understand the fundamental causes of tool failure. The objective was to achieve an order of magnitude increase in tool life, while machining at high speed, simply by reducing some of the failure mechanisms through different cutting strategies. Tool wear is described as a thermo-mechanical high-cycle fatigue phenomenon. The capability of a higher material removal per tool life is achieved in the case of PCD inserts compared to Tungsten carbide (WC). The average surface roughness produced was relatively low. The collected chips were also analyzed. The work demonstrated progress over the performance reported in current literature. The work confirms that there is a region where a sufficiently high temperature in the cutting zone may contribute to extended tool life, provided that the tool material can withstand these extreme conditions.
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Sartkulvanich, Partchapol. "Determination of material properties for use in FEM simulations of machining and roller burnishing." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1167412216.
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Rösth, Eric. "Ageing tests of cemented carbide powders : An investigation for increased quality of metal cutting inserts." Thesis, Uppsala universitet, Tillämpad materialvetenskap, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-355320.
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In this study, the ageing effects on powder used for cemented carbide insert production are examined. Ageing is throughout this study, defined as the time dependent change of the magnetic properties: coercive field strength and saturation magnetization. Testing is done using eight different powder compositions stored in both air and in an argon cabinet for 10 weeks, where sampling is done at specific intervals. Samples are stored in vacuum sealed bags for a combined sintering at the last phase of the test. Magnetic properties are assumed to be dependent on the amount of oxides needed to be reduced by taking carbon from the material itself during the vacuum stage of the sintering. To achieve interpretive results, this study also tested available sintering furnaces (DMK and DEK) by sintering trays with patterns of test pieces. This shows that DEK furnaces are much better for the ageing tests performed in this study, since less variation of the magnetic properties are measured because of the symmetrical heat gradient over each tray. Ageing tests strongly suggest that the cause of ageing comes from water absorbed by the PEG in the powder composition. Changing the molecular weight of the PEG seems to have an effect on the powder's ageing sensitivity. Measurements performed in this study show less ageing for Cr-rich DA-powders than for cubic carbide rich DQ-powders.
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Aiso, Toshiharu. "Workpiece steels protecting cutting tools from wear : A study of the effects of alloying elements on material transfer and coating damage mechanisms." Doctoral thesis, Uppsala universitet, Tillämpad materialvetenskap, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-306190.
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The vision of this thesis is to improve the machinability of workpiece steels. Workpiece material frequently transfers to the cutting tools during machining, and the transfer layers then forming on the tools may give both good and bad effects on machining performance and tool life. The objective of this work is to understand the effects of alloying element additions to workpiece steels on material transfer and the roles of the formed transfer layers on friction characteristics and wear of tools. To isolate and study the influence of the individual alloying elements, model steels are specifically designed. These steels include one reference with C as the only alloying element and others alloyed also with single additions or combined additions of 1 mass% Si, Mn, Cr and Al. The experiments are performed using both a sliding test, simulating the material transfer in milling, and a turning test. In a sliding contact, the mode of transfer is strongly dependent on the normal load and sliding speed. Material transfer initiates extremely fast, in less than 0.025 s, and characteristic transfer layers develop during the first few seconds. The different steel compositions result in the formation of different types of oxides in the transfer layers. At the workpiece/tool interface where the conditions involve high temperature, high pressure and low oxygen supply, easily oxidized alloying elements in the steel are preferentially transferred, enriched and form a stable oxide on the tool surface. The degree of enrichment of the alloying elements in the oxides is strongly related to their tendencies to become oxidized. The difference in melting temperature of the oxides, and thus the tendency to soften during sliding, explains the difference in the resulting friction coefficient. The widest differences in friction coefficients are found between the Si and Al additions. A Si containing oxide shows the lowest friction and an Al containing oxide the highest. The damage mechanism of coated tools is chiefly influenced by the form and shear strength of the transferred material. Absence of transfer layer or non-continuous transferred material leads to continuous wear of the coating. Contrastingly, continuous transfer layers protect it from wear. However, transfer layers with very high shear strength result in high friction heat and a large amount of steel transfer. This leads to rapid coating cracking or adhesive wear.
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Huang, Dengpeng [Verfasser]. "Meshfree modelling of metal cutting using phenomenological and data-driven material models / Dengpeng Huang." Hannover : Gottfried Wilhelm Leibniz Universität, 2020. http://nbn-resolving.de/urn:nbn:de:101:1-2021042902394807182339.
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Concetti, Alessia <1982>. "Integrated approaches for designing and optimizing thermal plasma processing for metal cutting and material treatment." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2011. http://amsdottorato.unibo.it/3883/.
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Kim, Sangseop. "Determination of Wall Thickness and Height when Cutting Various Materials with Wire Electric Discharge Machining Processes." BYU ScholarsArchive, 2005. https://scholarsarchive.byu.edu/etd/294.
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This thesis looks at the capabilities of cutting thin webs on Wire EDM machines that are difficult or impossible to machine using conventional methods. Covered is an investigation of how different material and web thickness affect the capability of machining thin-walled parts.
Five different metals are used for the test; Aluminum 6061 T6, Yellow Brass SS360, 420 Stainless Steel, D2 unheat-treated tool steel 25-30 RC, and D2 heat-treated tool steel 60-65 RC. The small parts were cut to a 6mm (0.2362 inch) height with six different wall thicknesses: 0.30mm (0.0118 inch), 0.25mm (0.0098 inch), 0.20mm (0.0078 inch), 0.15mm (0.0059 inch), 0.10mm (0.0039 inch), and 0.05mm (0.0020 inch). A Sodick AQ325L Wire EDM machine was utilized for testing.
The methods employed during the study include the following:
• Machine settings and offsets were limited to the default setting selected from the Sodick AQ325L database.
• Two different pre-test cuts were taken on the material to check for web bending during the cutting process.
• Hardness was tested for comparison of the web heights.
This thesis shows that bending increased as webs became thinner and that bending occurred toward the wire as the second side of the web was cut. Bending does affect the height of the web. Physical properties of materials also impacted the height of the web with the hardest material staying intact during the cutting process. This study shows that two factors, physical properties of materials and web thickness, significantly affect cutting results for thin web parts.
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Hammond, Derek. "An investigation of the impact of selected cooling strategies on milling of difficult-to-cut materials with an emphasis on titanium alloys and hardened steel." Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/80372.
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Thesis (MScEng)--Stellenbosch University, 2013.ENGLISH ABSTRACT: The aerospace- and automotive industries have an urgency to save space and reduce weight, as well as a need to increase fuel efficiency and reduce emissions. This has led to the use of lightweight structural materials, such as Ti6A14V alloy, which is the most widely used titanium alloy in the aerospace industry. This alloy has an exceptional strength-to-density ratio. The work also covers studies on tool steel 40CrMnMo7 that is used in applications in the tooling-, aerospace and automotive industry. In the quest for improved performance new alternative methods of efficiently machining these materials are investigated. One of the important criteria during machining of these materials is their machinability. This study discusses current research in high performance machining strategies and techniques for advanced materials such as Ti6Al4V and 40CrMnMo7. The properties that make these materials advantageous for the use in the aerospace- and automotive industry also make them difficult to cut. The widespread application of Ti6Al4V in the aerospace industry has encouraged investigations into cooling strategies or -techniques to maintain and improve tool life. Ti6Al4V has a low thermal conductivity causing the heat generated during machining to accumulate on the cutting edge of the tool. During various experiments the application of external compressed air blow cooling (dry cutting), flood cooling, high pressure through spindle cooling (HPTSC) and modifications thereof were investigated. The research project also evaluated the performance of a coating (TiAlN) and various coating treatments. The objectives of the HPTSC modifications were to improve the coolant stream impingement on the tool surface, effectively compressing the thermal barrier, and to reduce the chip-tool contact area. This would lead to a decrease in tool heating and wear. The modified techniques failed to increase tool life but showed signs of increased heat removal capability under the given conditions. It was observed that air blow cooling (dry cutting) delivered the best results when considering cutting materials, coating, coating treatment and cooling strategies or –techniques throughout the experiments conducted.
AFRIKAANSE OPSOMMING: Die Ruimte-en motor-industrie het 'n dringendheid om ruimte te bespaar en gewig te verminder, sowel as 'n behoefte om brandstofdoeltreffendheid te verbeter en emissies te verminder. Dit het gelei tot die gebruik van liggewig strukturele materiale, soos Ti6A14V Allooi , wat die mees gebruikte titanium allooi in die Ruimte is. Hierdie allooi het 'n uitsonderlike krag-tot-digtheid-verhouding. Die studie dek ook gereedskapstaal 40CrMnMo7 wat in die gereedskap, Ruimte-en motor-industrie aangewend word. In die soeke na verbeterde prestasie word nuwe alternatiewe metodes om effektief bewerking van hierdie materiaal ondersoek. Een van die belangrikste kriteria tydens bewerking van hierdie materiaal is die bewerkbaar daarvan. Hierdie studie bespreek die huidige navorsing in hoë prestasie bewerking strategieë en tegnieke vir gevorderde materiale, soos Ti6Al4V en 40CrMnMo7. Die eienskappe wat hierdie materiaal voordelig maak vir die gebruik in die lug-en Ruimte-en motor-industrie, maak dit terselfdetyd moeilik om te sny. Die wydverspreide toepassing van Ti6Al4V in die lug-en Ruimte industrie moedig ondersoeke aan na koelstrategieë of -tegnieke om die instrumentlewe te handhaaf en te verbeter. Ti6Al4V het lae termiese geleidingsvermoë wat veroorsaak dat die hitte, wat gegenereer word tydens bewerking, versamel op die voorpunt van die instrument. Tydens verskillende eksperimente was die toepassing van eksterne saamgeperste lugblaas-verkoeling (droë sny), vloed verkoeling, hoë-druk-deur-die-spil-afkoeling (HPTSC) en aanpassings daarvan geondersoek. Die navorsingsprojek het ook die prestasie van 'n bedekkingslaag (TiAlN) en verskeie bedekkingslaagbehandelings geëvalueer. Die doelwit van die HPTSC aanpassing was om die koelmiddelstroom beklemming op die instrument oppervlak te verbeter, en effektiewelik die termiese versperring saam te pers, asook die skerf-teenoorinstrument kontak te verminder. Dit sou lei tot 'n afname in die instrumentverwarming en -slytasie. Die gewysigde tegnieke het daarin misluk om die instrumentlewe te verhoog, maar het tekens getoon van 'n toename in hitte verwydering vermoë onder die gegewe omstandighede. Dit is dus waargeneem dat lugblaasverkoeling (droë sny) die beste resultate gelewer het in die oorweging van sny materiale, bedekkingslaag, bedekkingslaagbehandelings en verkoeling strategieë of -tegnieke wat regdeur die eksperimente uitgevoer was.
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Klazar, Martin. "Stanovení stupně vtažení zinkové povrchové vrstvy do hrany součástky v závislosti na použité technologii výroby - laserové řezání, vysekávání." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2014. http://www.nusl.cz/ntk/nusl-231072.
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The project, developed under the terms of engineering studies of the M-STG Manufacturing Technology branch, presents the analytical assessment of the cutting surface of the metal sheet by two most commonly used modern technologies of cutting, which is the laser beam division and the exact cutting. The evaluation of this area was mainly focused on the level of the penetration of the zinc surface layer in the area of the given cutting. With the help of modern methods of electron microscopy, these values of penetration were then estabilished for each technology. The analysis itself was preceded by literary studies of all individual parts participating in this experiment.
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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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Berglund, Anders. "Criteria for Machinability Evaluation of Compacted Graphite Iron Materials : Design and Production Planning Perspective on Cylinder Block Manufacturing." Doctoral thesis, KTH, Industriell produktion, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-48430.
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The Swedish truck industry is looking for new material solutions to achieve lighter engines with increased strength to meet customer demands and to fulfil the new regulations for more environmentally friendly trucks. This could be achieved by increasing the peak pressure in the cylinders. Consequently, a more efficient combustion is obtained and the exhaust lowered. This, however, exposes the engine to higher loads and material physical properties must therefore be enhanced. One material that could meet these demands is Compacted Graphite Iron (CGI). Its mechanical and physical properties make it ideal as cylinder block material, though there are drawbacks concerning its machinability as compared to other materials that are commonly used for the same purpose. Knowledge about machining of the material and its machinability is consequently inadequate. The main goal of this thesis is to identify and investigate the effect of the major factors and their individual contributions on CGI machining process behaviour. When the relationship between the fundamental features; machinability, material microstructure, and material physical properties, are revealed, the CGI material can be optimized, both regarding the manufacturing process and design requirements. The basic understanding of this is developed mainly through experimental analysis as, e.g., machining experiments and material characterization. The machining model presented in this thesis demonstrates the influence of material and process parameters on CGI machinability. It highlights machinability from both design and production planning perspectives. Another important objective of the thesis is an inverse thermo−mechanical FE model for intermittent machining of CGI. Here, experimental results obtained from a developed simulated milling method are used as input data, both to calibrate and validate the model. With these models, a deeper understanding is obtained regarding the way to achieve a stable process, which is the basis for future optimization procedures. The models can therefore be used as a foundation for the optimization of CGI component manufacturing.QC 20111121
MERA - OPTIMA CGI
FFI - OPTIMA phase two
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Campos, José Alexandre de. "Avaliação experimental do desgaste de canto durante o processo de eletroerosão do AISI H13." Universidade Tecnológica Federal do Paraná, 2014. http://repositorio.utfpr.edu.br/jspui/handle/1/1165.
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A fabricação de moldes e matrizes são ricas em detalhes e geometrias complexas, exigindo tecnologias mais inovadoras e precisas. Um dos processos que se destaca na fabricação de moldes e matrizes, é o de eletroerosão por penetração (Electrical Discharge Machining - EDM). A usinagem por descargas elétricas é classificada como um processo de fabricação de geometria não definida, onde a remoção de material é realizada por repetidas descargas elétricas entre dois eletrodos eletricamente condutores. O desgaste da ferramenta é um dos principais parâmetros de medida no desempenho da usinagem por EDM. O maior problema ocasionado pelo desgaste de canto do eletrodo é a mudança de geometria da ferramenta no decorrer da usinagem, alterando a tolerância geométrica e o dimensional da cavidade. O presente trabalho propõe avaliação dimensional do desgaste de canto do eletrodo, no decorrer da usinagem do processo de EDM, variando o ângulo de superfície frontal do eletrodo. Outro propósito é a criação de um índice, chamado de taxa de arredondamento, que leva em consideração as áreas de desgaste de canto do eletrodo em função da área removida de material da peça. Os resultados mostraram que os eletrodos de cobre, cobre tungstênio e grafite, tem um grande crescimento de raio de canto no inicio da usinagem, estabilizando esses valores com tempo maiores de processo. O ângulo de superfície frontal do eletrodo influência diretamente no desgaste de canto do eletrodo. Os eletrodos de grafite não apresentaram comportamento de arredondamento de desgaste de canto durante os ensaios. Para o índice de taxa de arredondamento os eletrodos de cobre tungstênio tiveram o menor valor apresentado na usinagem do AISI H13.The manufacture of molds and dies are rich in detail and complex geometries, requiring more innovative and precise technologes. One of the processes that stands out in the manufacture of molds and dies, is to EDM by penetration (Electrical Discharge Machining - EDM). The cutting by electrical discharge is classified as a non-defined geometry manufacturing process where material removal is carried out by repeated electrical discharge between two electrodes electrically conductive. The tool wear is a major measurement parameters in machining performance by EDM. The biggest problem caused by the electrode corner wear is the tool geometry change during the machining by changing the geometric tolerance and dimensional cavity. This paper proposes dimensional evaluation of the electrode corner wear, during the machining of the EDM process, varying the front surface of the electrode angle. Another purpose is to create an index, called rounding rate, which takes into account the areas of electrode corner wear due to the removed area of the workpiece material. The results showed that the copper electrode, copper tungsten and graphite, has a large corner radius growth at the beginning of machining, stabilizing these values with higher process time. The front surface of the electrode angle influence directly on the electrode corner wear. Graphite electrodes showed no corner wear rounding behavior during the tests. For rounding rate index tungsten copper electrodes had the lowest value presented in the machining of AISI H13.
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Oen, Richard James. "Measuring cutting forces on a metal cutting lathe." Ohio : Ohio University, 1989. http://www.ohiolink.edu/etd/view.cgi?ohiou1182447008.
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Oen, Jr Richard James. "Measuring cutting forces on a metal cutting lathe." Ohio University / OhioLINK, 1989. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1182447008.
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Kaymakci, Mustafa. "Generalized modeling of metal cutting mechanics." Thesis, University of British Columbia, 2009. http://hdl.handle.net/2429/12474.
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Metal cutting is the most commonly used manufacturing process for producing parts with final dimensions. The aim of engineering science is to model the physics of the process which allows the simulation of part machining operations ahead of costly trials. There is a need to develop generalized models of cutting process which is applicable to various tool geometries and cutting processes in order to simulate machining of industrial parts in virtual environment. This thesis presents a generalized mathematical model which can be used to predict turning, drilling, boring and milling processes.
The tool geometry is adopted from ISO 13399 standards. The rake face of the tool is mathematically modeled from ISO13399 model by considering tool geometry, engagement with the workpiece, feed and speed directions of cutting motion. Various geometric features of the tool, such as chamfer, nose radius, and cutting edge angles, are considered in developing coordinate transformation models between the machine motion and tool coordinate systems.
The cutting forces on the rake face are defined in the direction of chip flow and per-pendicular to the rake face. The cutting force coefficients in the two directions are either identified mechanistically by conducting experiments specific to the tool geometry, or using orthogonal to oblique transformation of shear angle, average friction angle and shear stress. The friction and normal forces on the rake face are transformed to both stationary and rotating tool coordinate systems defined on the machine tool.
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Darwish, S. M. H. "Adhesive bonding of metal cutting tools." Thesis, University of Birmingham, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.488941.
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The aim of this work is to develop techniques and to optimize the process of bonding of cemented carbide metal cutting inserts. This replaces the common methods of clamping or brazing. The first stage was to-survey and test structural adhesives to select the most promising adhesive for metal cutting applications. This resulted in a choice of toughened epoxy heat cured adhesive. A comparison between bonded and brazed joints, from the damping capacity point of view was made. In this comparison adhesive bonding resulted in, a higher damping capacity when compared with brazing. The bond line thickness proved to be significant in increasing the damping capacity of the bonded joints. A comparison was carried out between the heat flow through bonded and brazed tools, and demonstrated pronounced heat insulation in the bonded tool, which depended mainly both on the thermal conductivity of the adhesive material and the thickness of the bonded layer. The effectiveness of the bond line thickness, from the points of view of thermal conductivity and developed thermal stresses was investigated. This showed that the thinner the bond line the better is the performance of the bonded joint. The effect of coolant on the temperature of the bond line as well as the tool tip was also investigated. Mixing metallic powder with the adhesive material in order to increase the thermal conductivity of bonded tools was investigated. A new apparatus for measuring low thermal conductivity is proposed. Extensive cutting tests were carried out in order to assess the performance of bonded tools with and without coolant, reground tools and bonded tools having copper powder mixed with the adhesive. The assessment of cutting performance when using bonded tools compared with brazed tools showed that not only a better surface finish could be obtained with bonded tools but also far less tool flank wear
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Küsters, Niklas. "Halbanalytische Methode zur Charakterisierung der Fließortkurven von Blechwerkstoffen." THELEM Universitätsverlag und Buchhandlung GmbH und Co.KG, 2020. https://tud.qucosa.de/id/qucosa%3A72533.
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Numerische Prozessanalysen werden heute standardmäßig zur virtuellen Prozessabsicherung der Herstellung umgeformter Blechformteile eingesetzt. Die dabei notwendige hohe Prognosegüte kann nur mit einer hinreichend präzisen Materialmodellierung realisiert werden. Ein wesentlicher Aspekt ist dabei die Modellierung des Fließverhaltens und der Werkstoffanisotropie. Zur Charakterisierung des Werkstoffverhaltens existieren zahlreiche Versuchs- und Auswertestrategien; diese werden aufgrund des hohen Versuchs- und Rechenaufwands in der industriellen Anwendung jedoch nur vereinzelt eingesetzt.
Im Rahmen dieser Arbeit wird eine neuentwickelte halbanalytische Methode zur Charakterisierung von Fließortkurven sowie der Folgefließortkurven vorgestellt. Dazu wurde eine Spannungsanalyse auf Messdaten einer digitalen Bildkorrelation sowie ein Schnittlinienansatz zur Berechnung innerer Kräfte entwickelt. Durch Bilanzierung dieser inneren Schnittkräfte mit gemessenen äußeren Prüfkräften werden Parameter eines gewählten Materialmodells in einer inversen Analyse identifiziert. Die Methode zur Parameteridentifikation wurde zunächst an synthetischen und anschließend an realen Experimenten untersucht. Es wurde eine sequentielle Identifikationsstrategie aufgestellt, die an den Blechwerkstoffen DX54, DP600 sowie AA5182 untersucht wurde. Abschließend wurde die Methode mithilfe von Validierungsversuchen hinsichtlich der identifizierten Materialantworten überprüft.:Inhaltsverzeichnis I
Symbolverzeichnis IV
Abkürzungen und Begriffe VIII
1 Einleitung 1
2 Stand der Technik 3
2.1 Grundlagen zur Umformung von Blechwerkstoffen 3
2.1.1 Umformprozesse zur Herstellung von Blechformteilen 3
2.1.2 Anforderungen bei der Herstellung von Blechbauteilen 4
2.2 Numerische Prozessauslegung von Blechumformoperationen 5
2.2.1 Anwendung der FEM als Hilfsmittel in der Prozessauslegung 5
2.2.2 Kritische Punkte der numerischen Prozessauslegung 7
2.3 Werkstoffverhalten und Materialmodellierung 8
2.3.1 Kenngrößen zur Beschreibung großer Deformation 8
2.3.2 Grundlagen zur Beschreibung elastoplastischen Materialverhaltens 9
2.3.3 Beschreibung der Verfestigungsregel in Materialmodellen 11
2.3.4 Modellierung anisotroper Fließortkurven 12
2.3.5 Modellierung der Fließortkurvenentwicklung 18
2.3.6 Zusammenfassende Hinweise zu den Fließkriterien 25
2.4 Kennwertermittlung und Werkstoffcharakterisierung 26
2.4.1 Experimentelle Methoden und analytische Verfahren zur Fließortkurvenermittlung 26
2.4.2 Erweiterte Messtechnik zur Identifikation von Fließortkurven 33
2.4.3 Inverse Strategien zur Identifikation von Fließortkurven 36
2.5 Zusammenfassung zum Stand der Technik 43
3 Zielsetzung und Vorgehensweise 45
3.1 Zielsetzung 45
3.2 Vorgehensweise 45
4 Experimentelle Versuchsdurchführung 47
4.1 Versuchsaufbau und Messtechnik 47
4.2 Prüfverfahren zur Werkstoffprüfung 48
4.2.1 Zugversuch 49
4.2.2 Kerbzugversuch 49
4.2.3 Scherzugversuch 49
4.2.4 Biaxialer Zugversuch 50
4.3 Wahl der Versuchswerkstoffe 51
4.3.1 Kaltgewalzter Tiefziehstahl DX54 51
4.3.2 Kaltgewalzter Dualphasenstahl DP600 52
4.3.3 Aluminiumknetlegierung AA5182 52
4.4 Messergebnisse aus den Werkstoffprüfungen 53
4.5 Zusammenfassung zur Versuchsdurchführung 55
5 Entwicklung einer halbanalytischen Methode zur Parameteridentifikation 56
5.1 Spannungsanalyse 56
5.1.1 Spannungsrichtung 57
5.1.2 Spannungszuwachs 58
5.1.3 Elastische Kompensation 59
5.2 Schnittkraftermittlung 60
5.3 Inverse Analyse 62
5.4 Zusammenfassende Darstellung der Entwicklung 64
6 Validierung der Methode an virtuellen Experimenten 67
6.1 Virtuelle Versuche 67
6.2 Validierung der Spannungsanalyse 68
6.2.1 Vorgehensweise zur Prüfung der Spannungsanalyse 69
6.2.2 Ergebnisse der Überprüfung der Spannungsanalyse 70
6.3 Validierung der Schnittkraftermittlung 76
6.4 Sensitivität der Materialantwort gegenüber den Materialparametern 80
6.4.1 Einfluss variierender Fließkurvenapproximationen 80
6.4.2 Einfluss variierender Fließortkurven 82
6.5 Diskussion zur Wahl geeigneter Schnittlinien 88
6.6 Fehlerbetrachtung 89Numerical process analysis is widely used today for the virtual process validation of the production of formed sheet metal parts. In this context, sufficiently precise material modeling is essential, especially for the flow behavior and the material anisotropy. Numerous test and evaluation strategies are known for the material characterization. However, these strategies are only used occasionally in industrial applications due to high experimental and computational costs. In the context of this work, a newly developed semi-analytical method for the characterization of yield locus curves and subsequent yield locus curves is presented. For this purpose, a stress analysis based on digital image correlation data and a cutting-line approach for internal forces computation was developed. By balancing these internal cutting forces with measured external test forces, parameters of a material model are identified in an inverse analysis. The method for parameter identification was first examined on synthetic and subsequently on real experiments. A sequential identification strategy was set up and examined on the sheet metal materials DX54, DP600 and AA5182. Finally, the method was checked using validation tests with regard to the identified material responses.:Inhaltsverzeichnis I Symbolverzeichnis IV Abkürzungen und Begriffe VIII 1 Einleitung 1 2 Stand der Technik 3 2.1 Grundlagen zur Umformung von Blechwerkstoffen 3 2.1.1 Umformprozesse zur Herstellung von Blechformteilen 3 2.1.2 Anforderungen bei der Herstellung von Blechbauteilen 4 2.2 Numerische Prozessauslegung von Blechumformoperationen 5 2.2.1 Anwendung der FEM als Hilfsmittel in der Prozessauslegung 5 2.2.2 Kritische Punkte der numerischen Prozessauslegung 7 2.3 Werkstoffverhalten und Materialmodellierung 8 2.3.1 Kenngrößen zur Beschreibung großer Deformation 8 2.3.2 Grundlagen zur Beschreibung elastoplastischen Materialverhaltens 9 2.3.3 Beschreibung der Verfestigungsregel in Materialmodellen 11 2.3.4 Modellierung anisotroper Fließortkurven 12 2.3.5 Modellierung der Fließortkurvenentwicklung 18 2.3.6 Zusammenfassende Hinweise zu den Fließkriterien 25 2.4 Kennwertermittlung und Werkstoffcharakterisierung 26 2.4.1 Experimentelle Methoden und analytische Verfahren zur Fließortkurvenermittlung 26 2.4.2 Erweiterte Messtechnik zur Identifikation von Fließortkurven 33 2.4.3 Inverse Strategien zur Identifikation von Fließortkurven 36 2.5 Zusammenfassung zum Stand der Technik 43 3 Zielsetzung und Vorgehensweise 45 3.1 Zielsetzung 45 3.2 Vorgehensweise 45 4 Experimentelle Versuchsdurchführung 47 4.1 Versuchsaufbau und Messtechnik 47 4.2 Prüfverfahren zur Werkstoffprüfung 48 4.2.1 Zugversuch 49 4.2.2 Kerbzugversuch 49 4.2.3 Scherzugversuch 49 4.2.4 Biaxialer Zugversuch 50 4.3 Wahl der Versuchswerkstoffe 51 4.3.1 Kaltgewalzter Tiefziehstahl DX54 51 4.3.2 Kaltgewalzter Dualphasenstahl DP600 52 4.3.3 Aluminiumknetlegierung AA5182 52 4.4 Messergebnisse aus den Werkstoffprüfungen 53 4.5 Zusammenfassung zur Versuchsdurchführung 55 5 Entwicklung einer halbanalytischen Methode zur Parameteridentifikation 56 5.1 Spannungsanalyse 56 5.1.1 Spannungsrichtung 57 5.1.2 Spannungszuwachs 58 5.1.3 Elastische Kompensation 59 5.2 Schnittkraftermittlung 60 5.3 Inverse Analyse 62 5.4 Zusammenfassende Darstellung der Entwicklung 64 6 Validierung der Methode an virtuellen Experimenten 67 6.1 Virtuelle Versuche 67 6.2 Validierung der Spannungsanalyse 68 6.2.1 Vorgehensweise zur Prüfung der Spannungsanalyse 69 6.2.2 Ergebnisse der Überprüfung der Spannungsanalyse 70 6.3 Validierung der Schnittkraftermittlung 76 6.4 Sensitivität der Materialantwort gegenüber den Materialparametern 80 6.4.1 Einfluss variierender Fließkurvenapproximationen 80 6.4.2 Einfluss variierender Fließortkurven 82 6.5 Diskussion zur Wahl geeigneter Schnittlinien 88 6.6 Fehlerbetrachtung 89
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劉醒培 and Shing-pui Alex Lau. "Effect of air jet in metal cutting." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1985. http://hub.hku.hk/bib/B31207303.
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Lau, Shing-pui Alex. "Effect of air jet in metal cutting /." [Hong Kong : University of Hong Kong], 1985. http://sunzi.lib.hku.hk/hkuto/record.jsp?B12350060.
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Anderberg, Staffan. "A study of process planning for metal cutting." Licentiate thesis, University West, Division of Production Engineering, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:hv:diva-2147.
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Process planning as a function for competitiveness is often neglected. However, as an intermediary between product development and manufacturing, it holds a key function in transforming product specifications and requirements into a producible process plan. Demands and requirements should be met concurrently as manufacturing costs and lead times are minimised. The focus of this thesis is the act of process planning, where the use of better methodologies, computer-aids and performance measurements are essential parts. Since process planning has the function of transforming demands and requirements, changing customer and regulative requirements are vital to regard. Since environmentally benign products and production increases in importance, the research presented in this thesis includes a CNC machining cost model, which relates machining costs to energy consumption. The presented results in this thesis are based on quantitative and qualitative studies in the metal working industry.
This thesis has contributed to an enhanced understanding of process planning to achieve better performance and important areas for improvements. Despite a 50 year history of computerised process planning aids, few of these are used in the industry, where manual process planning activities are more common. Process planning aids should be developed around the process planner so that non-value adding activities, such as information management and documentation are minimised in order to allow more resources for value adding activities, such as decision making. This thesis presents a study of systematic process planning in relation to perceived efficiency. This correlation could however not be verified, which opens up for further studies of other possible explanations for process planning efficiency. Process planning improvements in the industry are difficult to make, since there is little focus on process planning activities and limited knowledge about actual performance hereof. This means that measures taken regarding process planning development are difficult to verify.
NFFP4
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Vaz, Junior M. "Computational approaches to simulation of metal cutting processes." Thesis, Swansea University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.639305.
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The purpose of this thesis is to develop numerical techniques to model and analyse metal forming operations involving material removal and ductile fracture. Due to the diversity and complexity of the physical phenomena involved, several different computational aspects of the problem have been addressed such as: computational strategies for general thermo-mechanical coupled problems accounting for heat generation due to plastic and frictional work, thermal contact, thermal strains and temperature dependent properties; ductile fracture criteria for damaged and conventional J2 elasto-plastic materials; and transfer operators for thermo-mechanical coupled problems and error estimates for damaged and conventional J2 elasto-plastic materials. The above techniques made possible studies on the following subjects: application of ductile fracture concepts to material separation in incipient chip formation and blanking; and application of error estimates and re-meshing procedures to high-speed machining. The technique developed in this thesis provide useful computational tools in the analysis of the phenomena involved in chip formation processes and constitute an advance with respect to numerical simulation of orthogonal machining.
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潘榮光 and Wing-kwong Digby Pun. "Factors affecting wear land stress in metal cutting." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1988. http://hub.hku.hk/bib/B31231330.
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Pun, Wing-kwong Digby. "Factors affecting wear land stress in metal cutting /." [Hong Kong] : University of Hong Kong, 1988. http://sunzi.lib.hku.hk/hkuto/record.jsp?B12361409.
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Zheng, Zi-Ming. "Theoretical analyses of wedge cutting through metal plates." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/38035.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1995.Vita.
Includes bibliographical references (leaves 171-174).
by Zi-Ming Zheng.
Ph.D.
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Lake, P. W. "Composite cutting tip and materials for mining tools." Thesis, Nottingham Trent University, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375097.
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Bil, Halil. "Simulation Of Orthogonal Metal Cutting By Finite Element Analysis." Master's thesis, METU, 2003. http://etd.lib.metu.edu.tr/upload/1049410/index.pdf.
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The aim of this thesis is to compare various simulation models of orthogonal
cutting process with each other as well as with various experiments. The effects
of several process parameters, such as friction and separation criterion, on the
results are analyzed. As simulation tool, commercial implicit finite element codes
MSC.Marc, Deform2D and the explicit code Thirdwave AdvantEdge are used.
Separation of chip from the workpiece is achieved either only with continuous
remeshing or by erasing elements according to the damage accumulated. From
the results cutting and thrust forces, shear angle, chip thickness and contact length
between the chip and the rake face of the tool can be estimated. For verification
of results several cutting experiments are performed at different cutting
conditions, such as rake angle and feed rate. Results show that commercial codes
are able to simulate orthogonal cutting operations within reasonable limits.
Friction is found to be the most critical parameter in the simulation, since good
agreement can be achieved for individual process variables by tuning it.
Therefore, simulation results must be assessed with all process variables and
friction parameter should be tuned according to the shear angle results. Plain damage model seems not appropriate for separation purposes of machining
simulations. On the other hand, although remeshing gives good results, it leads to
the misconception of crack generation at the tip of the tool. Therefore, a new
separation criterion is necessary to achieve both good physical modeling and
prediction of process variables.
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葉樹和 and Shu-wo Patrick Ip. "On the effect of air jet in metal cutting." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1994. http://hub.hku.hk/bib/B31211483.
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Bacci, Da Silva Marcio. "Lubrication in metal cutting under built-up edge conditions." Thesis, University of Warwick, 1998. http://wrap.warwick.ac.uk/57744/.
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The effect of a mineral oil lubricant and sulphur (an EP additive) on machining of medium carbon steel has been investigated. The lubricant was applied with several different concentrations an additive containing sulphur. The concentrations were 0%, 1 %, 2%, 3%, 4% and 5% of the additive. The results were compared with dry conditions. The effect of cutting speed and feed rate was also investigated. During the tests cutting force, transient surface temperature and surface finish were measured. Cutting force and surface finish were measured using traditional equipment. measure the temperature of the workpiece a new method was developed. The temperature of the transient surface was measured at three different positions below the cutting edge during the cut using an infrared sensor. The results were then extrapolated to obtain the temperature of the transient surface close to the cutting edge (the maximum temperature of the surface). The temperature results can be used to calculate the cooling rate of the surface. Quick stop tests were also used to obtain chip samples and information about BUB size and shape. The lubricant had no effect on forces, temperature or BUB size, but improved surface finish. This works suggests that the enhanced surface finish obtained when lubricant is applied is not due to lubrication on the rake face (preventing a BUE), but action on the machined surface after it has been formed. The BUE is squeezed parallel to the cutting edge and touches the workpiece altering the surface finish, by a rubbing action and also because periodically part of the BUB bonds to the surface. The lubricant works on this rubbing action and can avoid bonding of the squeezed BUE and also of debris particles that are inevitably formed during the operation. It has been shown that a very low volume of lubricant is enough to improve the surface finish because the area that requires lubrication is small.
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Ip, Shu-wo Patrick. "On the effect of air jet in metal cutting /." [Hong Kong] : University of Hong Kong, 1994. http://sunzi.lib.hku.hk/hkuto/record.jsp?B13793810.
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de, Melo Martins Araújo António João. "The generation mechanisms of acoustic emission in metal cutting." Thesis, University of South Wales, 2006. https://pure.southwales.ac.uk/en/studentthesis/the-generation-mechanisms-of-acoustic-emission-in-metal-cutting(3e759888-9eeb-4ca5-84eb-c723171fc896).html.
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The objective of the present thesis is the investigation of the generation mechanism of the ultrasonic vibrations, commonly called acoustic emissions (AE), detected during the course of metal cutting, since, although quite a lot of research effort has been put into the use of AE to monitor metal cutting condition, the mechanism by which AE is generated is still not fully understood. If chip generation is continuous, without built-up edge, and a sharp tool is used, continuous type AE is normally assumed. Most published models relate the energy of AE to the total cutting power, but this can be shown to be rather incorrect. Consequently, as continuous-type AE is mostly generated due to plastic deformation, and as dislocation motion is the main mechanism of plastic deformation of metals, a relationship between AE and dislocation motion is developed for the typical plastic deformation regimes encountered in metal cutting (due to the high temperatures, flow stress decreases with temperature in the so-called diffusion controlled regime, and due to the high strain rates, opposing viscous damping becomes the dominant mechanism governing dislocation movement). Although viscous damping governs the mechanics of deformation in metal cutting, it is proposed that AE is generated due to the interaction between dislocations and obstacles, since as a dislocation approaches an obstacle, strain energy is stored, which is rapidly released as soon as the dislocation surmounts the obstacle, resulting in the emission of an AE event. The detected AE is a result of many consequential likewise events. Consequently, a qualitative original model of AE generation is developed, in which the energetic level of AE is predicted to increase with strain and strain rate, but decrease with temperature, and the frequency content of AE is predicted to increase with strain rate, decrease with temperature, and remain unchanged with strain. In order to access the validity of the above-mentioned model, two sets of metal cutting experiments were accomplished for four different work materials, in which the cutting conditions were varied over a wide range, and the workpiece temperature was artificially modified. Both energy and frequency information were computed from the experimental data using the most appropriate data processing technics, i.e. AE mode and mean frequency, respectively. In addition, a semi-empirical metal cutting theory was utilized to predict basic metal cutting parameters. As the experimental results are in close agreement with the predictions provided by the qualitative model, it is concluded that the main source of AE in metal cutting comes from the interaction of moving dislocations with obstacles, whose dynamics is, however, dictated by viscous damping.
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Lu, Guoxing. "Cutting of a plate by a wedge." Thesis, University of Cambridge, 1989. https://www.repository.cam.ac.uk/handle/1810/250955.
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Sripathi, Prajwal Swamy Payton Lewis Nathaniel. "Investigation into the effects of tool geometry and metal working fluids on tool forces and tool surfaces during orthogonal tube turning of aluminum 6061 alloy." Auburn, Ala., 2009. http://hdl.handle.net/10415/1963.
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Negarestani, Reza. "Laser cutting of carbon fibre-reinforced polymer composite materials." Thesis, University of Manchester, 2010. https://www.research.manchester.ac.uk/portal/en/theses/laser-cutting-of-carbon-fibrereinforced-polymer-composite-materials(90c7dab8-2b05-4098-aee7-d90a66b9face).html.
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Carbon fibre-reinforced polymer (CFRP) composite materials are in increasingly high demand, particularly in aerospace and automotive industries for reduced fuel consumption. This is due to their superior structural characteristics (both in fatigue and static conditions) and light weight. Anisotropic and heterogeneous features of these materials, however, have posed serious challenges in machining of CFRPs. Hence new machining technologies need to be investigated. Laser is a non-contact (eliminating toolwear) thermal process. Therefore, the thermal properties of the material are of crucial importance. Especially for composite materials which consist of different constituent materials. In CFRPs, carbon fibres are excellent conductors of heat (thermal conductivity of 50 W/(m.K)) while the polymer matrix is poor conductor (thermal conductivity of 0.1-0.3 W/(m.K)). This significant difference that can be similarly traced for other thermal properties such as heat of vaporisation and specific heat capacity are the source of defects in laser cutting of CFRP composites. Major quality challenges in laser cutting of these materials are delamination and matrix recession. Various laser systems and cutting techniques are investigated in this work to minimise these defects. Multiple-pass cutting using a high beam quality continuous wave (CW) mode fibre laser is found to be effective to minimise delamination at low power level and high scanning speeds. Multiple-pass cutting using nanosecond pulsed DPSS Nd:YAG laser is shown to reduce matrix recession. A novel technique using mixing of reactive and inert gases is introduced and demonstrated to minimise the matrix recession. In order to improve the quality and dimensional accuracy of CFRP laser machining, it is important to understand the mechanism of transient thermal behaviour and its effect on material removal. A three-dimensional model to simulate the transient temperature field and subsequent material removal is developed, for the first time, on a heterogeneous fibre-matrix mesh. In addition to the transient temperature field, the model also predicts the dimensions of the matrix recession during the laser machining process.
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Armitage, Kelly. "Laser assisted machining of high chromium white cast-iron." Australasian Digital Thesis Program, 2006. http://adt.lib.swin.edu.au/public/adt-VSWT20070214.155302/index.html.
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Thesis (MEng) - Swinburne University of Technology, Industrial Research Institute Swinburne - 2006.A thesis submitted in fulfillment of the requirement for the degree of Master of Engineering by Research, Industrial Research Institute Swinburne, Faculty of Engineering and Industrial Sciences, Swinburne University of Technology - 2006. Typescript. Includes bibliographical references (p. 113-116).
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Haron, Che Hassan Che. "Machining of titanium alloys with coated and uncoated carbide tools." Thesis, Coventry University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.262998.
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Reeswinkel, Thomas [Verfasser]. "Self-lubricious tool coatings for ecological metal cutting / Thomas Reeswinkel." Aachen : Shaker, 2012. http://d-nb.info/1069046663/34.
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Movahhedy, Mohammad R. "ALE simulation of chip formation in orthogonal metal cutting process." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0019/NQ48680.pdf.
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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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FILHO, WALTER DE BRITTO VIDAL. "STUDY AND DEVELOPMENT OF COMPUTERIZED CUTTING MACHINE FOR FLEXIBLE MATERIALS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 1998. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=19807@1.
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COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIORO presente trabalho aborda o desenvolvimento e construção de um protótipo de uma máquina, de baixo custo, controlada por computador para corte de materiais flexíveis. A motivação deste é a crescente importância, no contexto da industria nacional, da manufatura com materiais flexíveis. Apesar de grande variedade de materiais usados na industria do vestuário, enfatiza-se aqui o corte de tecido. O problema abordado, consiste no controle simultâneo do três motores de passo e na escolha de uma ferramenta de corte mais adequada ao processo automatizado. O terceiro motor é a fixação do material. Por sua natureza flexível a fixação de alguns pontos não garantem a rigidez do conjunto podendo o tecido enrugar com a passagem da ferramenta de corte. Como será visto, o presente trabalho determinou uma configuração de porta-ferramentas e ferramenta que elimina o problema de fixação e simplifica o processo de corte, como também apresenta uma solução para eliminar a necessidade de um terceiro motor para o alinhamento da ferramenta à trajetória de corte.
The present research addresses the development and construction of a low cost prototype of a machine, controlled by computer, for automated cutting of flexible materials. The motivation for this research is the increasing importance, in the national industry context, of flexible material manufacturing. Although there is a great variety of flexible materials used in the garment industry, the emphasis lies on textile cutting. The problem consists in the simultaneous driving of three step Motors and the Best choice of cutting tools. The third motor is necessary to align the cutting balde tangentially to the desinred path. Another topic of research was how to fiz the fabric to the cutting table. Due to fabric flexibility, fixing just some points does´ntguarantee the stiffness of whole and can generate wrinkles during the cutting process. This research also considers the choice of rigth tool in order to eliminate the movement of fabric and simplify the cutting process. Finally, a solution for eliminating the necessity of the third motor to align the blade tangentially to the desired path has also been considered
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Pretorius, Cornelius. "Machining of titanium alloys with ultra-hard cutting tool materials." Thesis, University of Birmingham, 2013. http://etheses.bham.ac.uk//id/eprint/4385/.
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This research explores the relative merits of existing and novel ultra-hard tool materials for finish turning titanium alloys. Phase 1 of the experimental work comprised evaluating the machinability of Ti-6Al-2Sn-4Zr-6Mo when employing carbide tooling with respect to tool life, wear behaviour, workpiece surface integrity and cutting forces. The machinability of Ti-6Al-2Sn-4Zr-6Mo using PCBN tooling was evaluated in Phase 2 experiments. It was shown that even with the use of high pressure jet cooling, carbide and low content PCBN grade inserts were unsuitable for high-speed (~200 m/min) finish turning of titanium alloys. Phase 3 research evaluated the machinability of Ti-6Al-2Sn-4Zr-6Mo and Ti-6Al-4V when employing PCD tooling with respect to tool life, wear behaviour, workpiece surface integrity and cutting forces. Benchmark tests producing response surface models were developed using conventional low pressure fluid supply and were found to be suitable for the prediction of tool life, surface roughness and cutting force within the range of parameters studied. The PCD inserts significantly outperformed both carbide (by a factor > 24) and PCBN (by a factor > 12) tools in high-speed finish turning, although the performance varied depending on the PCD structure, edge geometry, period of engagement, undeformed chip thickness and jet fluid parameters.
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Ayub, Muhammad Azmi. "Automated two-dimensional patterned shape cutting of elastic web materials." Thesis, Loughborough University, 2004. https://dspace.lboro.ac.uk/2134/35242.
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The objective of this thesis is to automate the manual 2D-patterned cutting of lace with high a accuracy and quality of the cutting edges. Four main problems for automating the cutting method were addressed; feature recognition technique for cutting path extraction, material handling system, laser beam manipulation and trajectory planning generation. An integrated mechatronic approach for designing the automated laser cutting system was outlined. The features of the 2D-patterned lace fabrics are not exactly identical and easily distorted nonlinearly due to handling operations. An active template matching technique was developed and implemented to recognise the distorted features of the 2D-patterned shape cuttings. To accommodate the geometrical pattern variations, the cutting paths of the 2D-patterned shapes were extracted using either the chain-coding technique or the binary morphological techniques.
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Lazoğlu, İsmail. "Analysis of force system in ball-end milling." Diss., Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/16022.
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