Kliknij ten link, aby zobaczyć inne rodzaje publikacji na ten temat: Cutting metals.
Rozprawy doktorskie na temat „Cutting metals”
Utwórz poprawne odniesienie w stylach APA, MLA, Chicago, Harvard i wielu innych
Sprawdź 50 najlepszych rozpraw doktorskich naukowych na temat „Cutting metals”.
Przycisk „Dodaj do bibliografii” jest dostępny obok każdej pracy w bibliografii. Użyj go – a my automatycznie utworzymy odniesienie bibliograficzne do wybranej pracy w stylu cytowania, którego potrzebujesz: APA, MLA, Harvard, Chicago, Vancouver itp.
Możesz również pobrać pełny tekst publikacji naukowej w formacie „.pdf” i przeczytać adnotację do pracy online, jeśli odpowiednie parametry są dostępne w metadanych.
Przeglądaj rozprawy doktorskie z różnych dziedzin i twórz odpowiednie bibliografie.
1
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.
Pełny tekst źródła
2
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.
Pełny tekst źródłaStreszczenie:
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.
3
Aguiar, Marcelo Mendes de. "Análise da influência das condições de corte sobre o fresamento em acabamento de aços endurecidos usando altas velocidades". [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/264165.
Pełny tekst źródłaStreszczenie:
Orientador: Anselmo Eduardo DinizDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica
Made available in DSpace on 2018-08-19T18:33:44Z (GMT). No. of bitstreams: 1 Aguiar_MarceloMendesde_M.pdf: 3795090 bytes, checksum: a76ee2a93e8e7595881459d7a6d71b50 (MD5) Previous issue date: 2012
Resumo: Normalmente, a utilização de aços ferramenta endurecidos, juntamente com as formas complexas típicas das peças utilizadas na área de moldes e matrizes, oferecem dificuldade na usinagem por fresamento, principalmente nas operações de acabamento que exijam o uso de ferramentas longas. A técnica de fresamento HSM (High Speed Machining - usinagem em altas velocidades, ou ainda High Speed Milling - fresamento em altas velocidades) tem se tornado uma alternativa para realizar este tipo de usinagem, reduzindo, ou às vezes até eliminando operações de eletro-erosão e polimento. Tipicamente, as fresas de pastilhas de metal duro intercambiáveis tem sido usadas em operações de desbaste e semi-acabamento, enquanto nas operações de acabamento ou em usinagem de geometrias que exijam ferramentas com pequenos diâmetros ainda predomina o uso de fresas inteiriças. O objetivo principal deste estudo é avaliar a influência de cinco variáveis de processo de fresamento com alta velocidade de corte, sobre o acabamento da superfície usinada. A influência do desgaste das ferramentas sobre o acabamento superficial, ao longo de 400 minutos de usinagem, também foi avaliado, além de uma comparação entre ferramentas inteiriças de metal duro e ferramentas de pastilha intercambiável montada em corpo de metal duro, a fim de avaliar a viabilidade técnica do uso deste segundo tipo de ferramenta, em substituição às tradicionais fresas inteiriças utilizadas em operações de acabamento. Na maioria dos experimentos realizados, pequenos valores de rugosidade foram mantidos, demonstrando que operações de acabamento em aço ABNT H13 IM com dureza de 50 HRC é possível com vida longa de ferramenta, mesmo utilizando-se valor de 500 m/min para velocidade de corte. Além disto, a análise da influência das variáveis de processo utilizadas neste trabalho mostrou que é possível, sob algumas condições, utilizar tanto ferramentas inteiriças, quanto de pastilha intercambiável montada em corpo de metal duro em operações de acabamento
Abstract: Typically, the use of hardened tool steels, along with complex shapes typical of the parts used in the field of molds and dies, offer difficulty in machining by milling, mainly in finishing operations that demand the use of long tool. The HSM (High Speed Machining or High Speed Milling) has become a possible alternative for making this type of machining, reducing, or sometimes eliminating electric discharge machining and polishing operations. Usually, indexable carbide insert mills has been used for roughing and semi-finishing, while in finishing operations or when the machining geometries that require tools with small diameters the integral tools are used yet. The main objective of this study is to evaluate the influence of five process variables, with high cutting speed, on the finish of the machined surface. The influence of tool wear on surface finish through 400 minutes of milling was also evaluated, as well as a comparison between integral carbide mills and indexable insert mounted at cemented carbide toolholder endmills, in order to evaluate the technical feasibility of using this second type of tool, replacing the traditional integral carbide endmills used in finishing operations. In most experiments, small roughness values were maintained, showing that finishing operations on AISI H13 IM with a hardness of 50 HRC is possible with long tool life, even using the cutting speed of 500 m/min. Furthermore, the analysis of the influence of process variables used in this study showed that is possible, under some conditions, the use either integral carbide tools, or indexable insert mounted at cemented carbide toolholder endmills on finishing operations
Mestrado
Materiais e Processos de Fabricação
Mestre em Engenharia Mecânica
4
Svanberg, Andreas. "Numerical Methods for Simulating the Metal Shearing Process : A Novel Numerical Model for the Punching of Metals". Thesis, Luleå tekniska universitet, Material- och solidmekanik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-72742.
Pełny tekst źródłaStreszczenie:
When dealing with the separation of materials, the metal shearing process such as punching, is widely used in theindustry due to its time efficient manner. There is however, a need to better understand the process in order toimprove quality of the final product. Working with numerical simulations of themetal shearing process, there aretwo major difficulties. One being the extremely large deformation, the other being material failure. The combinationof these two makes numerical modeling challenging and is the reason for this study.The problem was divided in to two main parts, one where material modeling was studied, the other part focusedon numerical modeling and experiments of the punching process. A material model considering both plasticityandmaterial failure was created for a boron steel material. Plasticity behavior of thematerial was modeled with anelasto-plastic model and a calibratedModifiedMohr-Coulomb (MMC) failure criterion to model the material failure.The resultingMMC-model agreed well with the experiments.Punching experiments with varying clearances were performed on the boron steel. Punch forces and displacementswere continuously sampled throughout the process, and after the punching experiments were finished the punchededge profiles were studied. The multiphysics simulation software LS-DYNA was then utilized, and three dimensionalsimulations of the punching process using the Smoothed Particle Galerkin (SPG)method were performed.Results from the SPG-simulation corresponded very well with the results from punching experiments, and it can beconcluded that the model was able to capture the material behavior of the sheet in a highly detailed level. When thepunched edge profiles from the simulations were compared to the experiments, there was an almost exact match forall the cases studied. The force-displacement behavior of the punch from simulations was in great consistency withexperimental results as well.Itwas also concluded that the combination of a stress state dependent failure criterion together with the SPG-methodshows significant possibilities to cope with three dimensional problems where large deformations in combinationwith difficultmaterial failure occurs. This study focuses on the punching process, but the generality of this novelmodeling technique can be applied to many industrial cases and is a step towards a better and more reliablemodeling of failure in combination with extremely large deformation.
5
Stephenson, Richard C. "Comparing the Feasibility of Cutting Thin-Walled Sections from Five Commonly Used Metals Utilizing Wire Electric Discharge Machining". Diss., CLICK HERE for online access, 2007. http://contentdm.lib.byu.edu/ETD/image/etd1948.pdf.
Pełny tekst źródła
6
Karap, Vandana. "Preliminary Assessment: Identification of Chinese Drywall and Exposure to Particulate Matter and Metals during Cutting and Installation of Drywall". ScholarWorks@UNO, 2011. http://scholarworks.uno.edu/td/1321.
Pełny tekst źródłaStreszczenie:
Drywall, a popular building material made of gypsum based plaster sandwiched between two thick sheets of paper is used for building interior walls, is speedier alternative to traditional plaster, decreasing time and labor for construction. Importance of drywall increased with the demand for drywall after nine hurricanes hit Florida in 2004-05 and widespread damage caused in the Gulf Coast after Katrina in 2005. This study has two parts. First part presents an analysis of metals like strontium for the identification of Chinese drywall, and a comparison of strontium concentrations of American drywall and Chinese drywall using XRF (X-Ray Fluorescence) analysis with the Innov-X XRF analyzer. The second part presents an analysis of metal exposure during cutting and installation of drywall using 8stage Cascade impactor. The work space concentration of, different metals is analyzed using XRF analysis and particulate matter within various size ranges, were calculated and their effects are studied.
7
Sasse, Ina [Verfasser]. "Schneiden und Schweißen strukturierter Bleche mit Faserlaser : Cutting and welding of structured sheet metals with fiber laser / Ina Sasse". Aachen : Shaker, 2014. http://d-nb.info/1059344416/34.
Pełny tekst źródła
8
Deonisio, Carlos Cesar de Castro. "Estudo do fresamento do aço D2 endurecido em altas velocidades de corte". [s.n.], 2004. http://repositorio.unicamp.br/jspui/handle/REPOSIP/264271.
Pełny tekst źródłaStreszczenie:
Orientador: Olivio NovaskiTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica
Made available in DSpace on 2018-08-05T07:03:19Z (GMT). No. of bitstreams: 1 Deonisio_CarlosCesardeCastro_D.pdf: 16365372 bytes, checksum: fb0542af08c6aa67ad7bd3a1a196a1f3 (MD5) Previous issue date: 2004
Resumo: O principal objetivo deste trabalho é caracterizar a qualidade da superfície gerada no processo de fresamento em acabamento, com fresas de topo esférico, do aço para trabalho a frio ABNT D2, endurecido. Utilizou-se o método do planejamento fatorial e as variáveis de influência foram às condições de contato entre a ferramenta e a superfície usinada, os parâmetros de corte e o desgaste de flanco da ferramenta de corte (VB). O aumento da velocidade de corte muda o mecanismo de formação do cavaco, causando a diminuição da razão entre o aumento dos esforços de usinagem e da deflexão da ferramenta de corte em relação ao aumento da velocidade de corte, decorrente da mudança na distribuição de temperatura entre a ferramenta de corte, a peça e o cavaco. Há interação entre a velocidade de corte, o sobrematerial e o avanço, em relação à deformação, encruamento e conseqüente endurecimento da superfície usinada. O desgaste da ferramenta de corte tem significativa influência na integridade da superfície gerada. A velocidade de corte e o avanço por dente influenciam na segmentação do cavaco
Abstract: The main goal of this investigation is to characterize the quality of the generated surface, in the process of finishing milling, of the hardened steel for cold work ABNT D2. The method of factorial planning was used and the variables of influence were the conditions of contact between the cutting tool and the machined surface, the cutting parameters and the cutting tool wear. The increase of the cutting speed change the mechanism of chip formation, causing the reduction of the ratio of the increase of machining forces and the deflection of the cutting tool in relation to the increase of the cut speed, because of the change in the distribution of temperature between the tool, the part and the chip. There is interaction between cutting speed, feed rate and stock removal, in relation the deformation, strain hardening and consequent hardening of the surface machining. The wear of the cutting tool has significant influence in the integrity of the generated surface. The cutting speed and the feed for tooth influence the segmentation of the chi
Doutorado
Materiais e Processos de Fabricação
Doutor em Engenharia Mecânica
9
Hostinský, Michal. "Nekonvenční technologie výroby řetězů". Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-232064.
Pełny tekst źródłaStreszczenie:
Unconventional technologies and their continual development brings along new possibilities in the manufacturing process. The submitted project is focused on solving problems in the procession of sheet metals in the manufacture of special parts of roller and conveyor chains. In the assessment of the technology of components, laser cutting was evaluated as the most optimal technology. With this goal, there was a public tender in terms of the purchase of a new machine designed for the manufacturing operations of the company of RETEZY Vamberk. This company ranks among the most major manufacturers of conveyor, roller and special chains in Europe.
10
Pilarčík, Edmund. "Studium kvality řezu hliníkových a Cu slitin při tavném řezání v závislosti na procesních parametrech při laserovém dělení s využitím YbYAG vláknového laseru". Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2016. http://www.nusl.cz/ntk/nusl-241860.
Pełny tekst źródłaStreszczenie:
The diploma thesis discusses laser cutting of non-ferrous metals using fiber YbYag laser and evaluation of the roughness of cutting edge samples. To manufacture samples of aluminium Al 99,5, deoxidized copper Cu – DHP and brass CuZn37 were used combinations of process parameters according to Taguchi statistical method. Samples were subsequently evaluated, according to the ČSN EN ISO 9013 standard and sorted into roughness cathegories, and by technical and economical evaluation, the most economical process parameter combinations were found. Experimantal part is preceded by description of general methods of cutting, description of laser types, process parameters and their influence on the occurrence of the cutting edge defects and description of roughness measurement and standard ČSN EN ISO 9013.
11
Oen, Richard James. "Measuring cutting forces on a metal cutting lathe". Ohio : Ohio University, 1989. http://www.ohiolink.edu/etd/view.cgi?ohiou1182447008.
Pełny tekst źródła
12
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.
Pełny tekst źródła
13
Ventura, Carlos Eiji Hirata. "Estudo dos esforços de corte no processo HSM aplicado à abertura de cavidades". [s.n.], 2010. http://repositorio.unicamp.br/jspui/handle/REPOSIP/264917.
Pełny tekst źródłaStreszczenie:
Orientador: Amauri HassuiDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica
Made available in DSpace on 2018-08-16T19:30:43Z (GMT). No. of bitstreams: 1 Ventura_CarlosEijiHirata_M.pdf: 5734965 bytes, checksum: 2b91710d6113e0caaa9313bbc9b54acf (MD5) Previous issue date: 2010
Resumo: A manufatura de um grande número de componentes na indústria depende de moldes e matrizes para processos como forjamento, metalurgia do pó, estampagem, fundição e injeção de plástico. Uma das principais operações para a fabricação destas peças corresponde à abertura da cavidade inicial, a partir da qual geometrias mais complexas são usinadas a fim de se obter o negativo do produto final. Sendo esta uma operação de desbaste, verificam-se altos esforços de corte e desgaste significativo da ferramenta. A fim de se reduzir tais grandezas, além de melhorar o acabamento (diminuindo-se o tempo necessário para semi-acabamento e acabamento final), diversas estratégias de entrada da ferramenta e de corte interno têm sido propostas. Neste contexto, o trabalho irá avaliar três diferentes estratégias para abertura de cavidades pelo método HSM em um aço AISI D2, sendo cada uma delas caracterizada pela ferramenta utilizada (I: fresa de alto avanço, II: fresa toroidal e III: fresa de mergulho), parâmetros de corte, estratégia de entrada (I: rampa, II: hélice e III: mergulho) e de corte interno (I: espiral, II: ziguezague, III: não há). Em cada uma delas serão analisados estática e dinamicamente os esforços de corte em cada trecho da cavidade e a vida da ferramenta. Além disso, é proposto ainda um modelo de forças para as diferentes formas de entrada da ferramenta na peça, que leva em conta as peculiaridades de cada estratégia. Verificou-se que o principal mecanismo de desgaste associado a todas as estratégias corresponde à adesão, fenômeno intimamente ligado à vibração do processo, excitado principalmente nos trechos em que a ferramenta tangencia as paredes menos rígidas da cavidade. Já em relação ao modelo, comprovou-se sua utilidade na avaliação prévia dos esforços médios
Abstract: The manufacturing of a great number of components in the industry depends on molds and dies used in processes like forging, powder metallurgy, deep drawing, casting and plastic injection. One of the main operations for manufacturing of these parts corresponds to the opening of the initial pocket, from which more complex geometries are machined in order to obtain the negative face of the final product. As this is a rough operation, it is characteristic of the process high cutting forces and a significant tool wear. Aiming to reduce such variables and to improve the finishing (decreasing the time for semi- and end finishing), many entry- and internal cutting strategies have been proposed. In this context, the work will evaluate three different strategies for pocket milling by HSM method in AISI D2 steel, which are characterized by the used tool (I: high-feed mill, II: torus mill and III: plunge mill), cutting parameters, entry strategy (I: ramp, II: helical and III: plunge) and internal cutting strategy (I: spiral, II: zigzag and III: no cutting). In each of the mentioned strategies not just the tool life, but also the cutting forces in each interval of the pocket will be analyzed statically and dynamically. Moreover, it is also proposed a cutting force model for the different entry strategies, taking into account their peculiarities. It was noted that the main wear mechanism associated with all strategies corresponds to adhesion, which is closely related to the vibration in the process, excited mainly in the intervals where the tool touch the less rigid walls of the pocket. Considering the model, its usefulness in the evaluation of the average cutting forces was proved
Mestrado
Materiais e Processos de Fabricação
Mestre em Engenharia Mecânica
14
Kaymakci, Mustafa. "Generalized modeling of metal cutting mechanics". Thesis, University of British Columbia, 2009. http://hdl.handle.net/2429/12474.
Pełny tekst źródłaStreszczenie:
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.
15
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.
Pełny tekst źródłaStreszczenie:
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
16
Abrari, Farid. "Multi-axis milling of flexible parts /". *McMaster only, 1998.
Znajdź pełny tekst źródła
17
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.
Pełny tekst źródłaStreszczenie:
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).
18
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.
Pełny tekst źródła
19
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.
Pełny tekst źródła
20
劉醒培 i 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.
Pełny tekst źródła
21
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.
Pełny tekst źródła
22
Lu, Guoxing. "Cutting of a plate by a wedge". Thesis, University of Cambridge, 1989. https://www.repository.cam.ac.uk/handle/1810/250955.
Pełny tekst źródła
23
潘榮光 i 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.
Pełny tekst źródła
24
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.
Pełny tekst źródła
25
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.
Pełny tekst źródłaStreszczenie:
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
26
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.
Pełny tekst źródłaStreszczenie:
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.
27
Zheng, Zi-Ming. "Theoretical analyses of wedge cutting through metal plates". Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/38035.
Pełny tekst źródłaStreszczenie:
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.
28
Lazoğlu, İsmail. "Analysis of force system in ball-end milling". Diss., Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/16022.
Pełny tekst źródła
29
Wang, Jiunn-Jyh Junz. "Convolution modeling of milling force system and its application to cutter runout identification". Diss., Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/17318.
Pełny tekst źródła
30
葉樹和 i 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.
Pełny tekst źródła
31
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.
Pełny tekst źródła
32
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.
Pełny tekst źródłaStreszczenie:
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.
33
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.
Pełny tekst źródłaStreszczenie:
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.
34
Bacci, Da Silva Marcio. "Lubrication in metal cutting under built-up edge conditions". Thesis, University of Warwick, 1998. http://wrap.warwick.ac.uk/57744/.
Pełny tekst źródłaStreszczenie:
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.
35
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.
Pełny tekst źródłaStreszczenie:
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.
36
Park, Young-Bin. "Sheet metal forming using rapid prototyped tooling". Diss., Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/18361.
Pełny tekst źródła
37
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.
Pełny tekst źródłaStreszczenie:
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.
38
Rivero, Paz Ive. "The effect of key microstructure features on the machining of an aluminum-silicon casting alloy /". View online, 2010. http://ecommons.txstate.edu/engttad/1.
Pełny tekst źródła
39
Reeswinkel, Thomas [Verfasser]. "Self-lubricious tool coatings for ecological metal cutting / Thomas Reeswinkel". Aachen : Shaker, 2012. http://d-nb.info/1069046663/34.
Pełny tekst źródła
40
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.
Pełny tekst źródła
41
Awan, Muhammad Rizwan. "Specific energy consumption of metal cutting with thin abrasive discs". Doctoral thesis, Universitat Politècnica de Catalunya, 2021. http://hdl.handle.net/10803/672919.
Pełny tekst źródłaStreszczenie:
The aim of this research is to provide an in-depth understanding of energy consumption in abrasive disc cutting processes. The specific energy consumed in cutting is measured,analysed, and then characterised in to three components. To this end, an experimental device is built using an Arduino-controlled grinder to measure the specific energy consumed by cutting at different feed rates. Using a model, the experimental data is validated and the Specific Energy Consumed is separated into three energy components: sliding, ploughing and specific cutting energy. Furthermore, the influence of cutting conditions and material properties significantly influenced the specific energy consumption and its components.
To analyse the effect of grain shape and the relative dependence of the different components of the Specific Energy Consumed as a function of material removal rate, integral models of specific ploughing energy, specific sliding energy and specific cutting energy are developed. Conventional and super abrasive cubitron abrasive grains were used. Cutting with pyramidal abrasive discs (cubitron) was used for the determination of the relative components of the specific energy consumed. It was found that the specific ploughing energy is more sensitive to the change in material removal rate compared to the sliding energy. Due to the fast shearing and precisely shaped cubitron grains, the transition from sliding to a specific shear regime was so fast for some materials that the magnitude of the ploughing energy was found to be negligible.However, the model implementation for some materials showed that the absence or presence of ploughing energy also depends on the rate of material removed.
Finally, the development of a cutting grain model is presented which will allow the study of the chip compression ratio which is not possible to characterise by means of a single cutting grain in metal cutting with thin abrasive discs. This latest development is the beginning of a study of chip formation in the primary cutting zone of an abrasive grain.
This research provides a machine and a methodology to characterise cutting with commercially available abrasive discs in terms of the Specific Energy Consumed parameter.El objetivo de esta investigación es proporcionar un conocimiento profundo sobre el consumo de energía en los procesos de corte con discos abrasivos. Se mide y analiza la energía específica consumida en el corte, caracterizando dicha energía en tres componentes. Para ello se construye un dispositivo experimental que utiliza una amoladora controlada por un Arduino, para medir la energía específica consumida por el corte a diferentes velocidades de alimentación. Utilizando un modelo, se validaron los datos experimentales y se separa la Energía Específica Consumida en tres componentes energéticos: deslizamiento, arado y energía de corte específica. Además, la influencia de las condiciones de corte y las propiedades del material influyeron significativamente en el consumo de energía específico y sus componentes. Para analizar el efecto de la forma del grano y la dependencia relativa de las diferentes componentes de la Energía Específica Consumida en función de la tasa de remoción de material. Se desarrollan modelos integrales de energía de arado específica, energía de deslizamiento específica y energía de corte específica. Se utilizaron granos abrasivos convencionales y súper abrasivos de Cubitrón. El corte con discos abrasivos de granos piramidales (cubitron) se utilizaron para la determinación de las componentes relativas de la energía específica consumida. Se encontró que la energía de arado específica es más sensible al cambio en la tasa de remoción de material en comparación con la energía de deslizamiento. Debido a los granos de Cubitrón de corte rápido y de forma precisa, la transición de deslizamiento a un régimen de corte específico fue tan rápida para algunos materiales que la magnitud de la energía de arado resultó ser insignificante. Sin embargo, la implementación del modelo para algunos materiales demostró que la ausencia o presencia de energía de arado también depende de la tasa de material removido. Por último se presenta el desarrollo de un modelo de grano de corte que permitirá estudiar la relación de compresión de la viruta que no es posible caracterizar a través de un solo grano de corte en el corte de metales mediante discos abrasivos delgados. Este último desarrollo es el comienzo de un estudio de la formación de viruta en la zona primaria de corte de un grano abrasivo. Esta investigación proporciona una máquina y una metodología para caracterizar el corte con disco abrasivos, disponibles comercialmente, en términos del parámetro Energía Específica Consumida.
Enginyeria mecànica, fluids i aeronàutica
42
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.
Pełny tekst źródłaStreszczenie:
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.
43
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.
Pełny tekst źródła
44
Medaska, Michael Kenneth. "The measurement of temperatures and forces in a turning operation with cutting fluid". Thesis, Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/15983.
Pełny tekst źródła
45
Butcher, Timothy Jon. "An evaluation of hypermedia information systems support for CNC machinists". Thesis, Cranfield University, 2003. http://dspace.lib.cranfield.ac.uk/handle/1826/114.
Pełny tekst źródłaStreszczenie:
As information technology (IT) capabilities increase, manufacturing businesses are realigning their information systems infrastructure to remain competitive. This has resulted in substantial increases in IT use in technical areas of the business. Nevertheless, conventional paper-based information systems are still common at the shopfloor. Hence, manufacturers need to understand whether there is any benefit in extending IT functionality to the shopfloor. The focus of this research is the support of the CNC machinist, who has a specific set of craft skills and knowledge that are a core business capability in the metal cutting industry. By evaluating the impact of hypermedia information systems upon the independent decision-making and communication capabilities of CNC machinists, this research aims to provide an understanding of the shopfloor performance benefits of replacing existing paper-based systems with this relatively new technology. This research finds that in CNC machining environments where there are limited divisions of labour, hypermedia-based manufacturing instructions support CNC machinist independent decision-making and cross-boundary communications as effective as paper-based manufacturing instructions. CNC machinists also demonstrate an acceptance of the new technology. Hence, the sponsor and the research community can pursue continued research to develop the technical and social systems to achieve predicted business benefits.
46
Ghadimzadeh, Seyed Reza. "Machining of hypereutectic aluminium-silicon alloy". Thesis, Coventry University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.281726.
Pełny tekst źródła
47
Li, Junjian. "The investigation of temperature in single point cutting in conjunction with thermal imaging techniques". Thesis, Northumbria University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367405.
Pełny tekst źródła
48
Graver, Thomas William. "Determination of cutting-tool inventory levels in a flexible manufacturing system". Thesis, Georgia Institute of Technology, 1987. http://hdl.handle.net/1853/30775.
Pełny tekst źródła
49
Lara, Adriano Perpétuo de. "Análise das vibrações no processo de torneamento interno da liga de alumínio 6351-T6". Universidade Tecnológica Federal do Paraná, 2017. http://repositorio.utfpr.edu.br/jspui/handle/1/2984.
Pełny tekst źródłaStreszczenie:
Este trabalho tem como objetivo analisar as vibrações no processo de torneamento interno utilizando um porta ferramentas com a relação comprimento/diâmetro alta. Ferramentas com alto comprimento em balanço são susceptíveis a ocorrência de vibrações regenerativas durante a usinagem, alterando a estabilidade dinâmica do processo e gerando um acabamento superficial indesejado. Testes realizados para a obtenção de dados foram feitos utilizando equipamentos de medição como microfone e plataforma para medição das forças. A proposta foi de analisar a influência de parâmetros de usinagem como rotação e profundidade de corte na estabilidade dinâmica do processo de torneamento interno da liga de alumínio 6351-T6. Para isso utilizou-se os dados gerados na elaboração de uma carta de estabilidade do processo. Simultaneamente efetuou-se as simulações no software Matlab utilizando um modelo pré-estabelecido e comparando com os resultados experimentais obtidos. Para a análise dos dados coletados pelo microfone utilizou-se uma placa de aquisição de sinais, um microcomputador e um software para análise, o ITA-Toolbox. Baixas velocidades de corte propiciam maiores profundidades de corte limite devido ao efeito de amortecimento. Os resultados mostraram que este fenômeno começa a ser significativo quando a relação entre a frequência de vibração e a frequência de rotação é de aproximadamente 30 e aumenta consideravelmente para uma relação de 60. Os resultados também mostraram que para profundidades de corte abaixo do raio de ponta da ferramenta tem-se cortes instáveis porém de acordo com os modelos existentes na literatura, para um valor suficientemente abaixo da profundidade de corte o processo é sempre estável.This work aims to analyze the vibrations in the boring process using a tool holder with high overhang. Tools with high overhang are susceptible to the occurrence of regenerative vibrations during machining, altering the dynamic stability of the process and generating an undesired surface finish. Tests performed to obtain data were made using measuring equipment such as microphone and platform for measuring forces. The proposal was to analyze the influence of machining parameters such as cutting speed and depth of cut in the dynamic stability of the aluminium alloy 6351-T6 boring process. For this purpose, the data generated in the process stability chart was used. Simulations were performed in the Matlab software using a previous model and compared with the experimental results. For the analysis of the data collected were used a microphone, a signal acquisition board, a microcomputer and a software for analysis, the ITA-Toolbox .In the end, the results showed that the depth of cut and the cutting speed have great influence on the vibration and on the stability of the boring process. Low cutting speeds provide greater cut depth of cut due to the damping effect. The results showed that this phenomenon begins to be significant when the relation between the frequency of vibration and the frequency of rotation is of approximately 30 and increases considerably to a ratio of 60. The results also showed that for depths of cut below the tool nose radius has unstable cuts but according to the models in the literature, for a value sufficiently below the depth of cut the process is always stable.
50
El-Kurdi, Zeyad Mechanical & Manufacturing Engineering Faculty of Engineering UNSW. "Monitoring and control of the CO2 laser cutting process". Awarded by:University of New South Wales. School of Mechanical and Manufacturing Engineering, 2005. http://handle.unsw.edu.au/1959.4/21900.
Pełny tekst źródłaStreszczenie:
Laser cutting is one of the most important applications of laser in manufacturing industry; it is mainly used for sheet metal cutting. In laser cutting, performing real-time evaluation of laser cut quality is very important to the advancement of this process in industry. However, due to the dynamic nature of the laser cutting process specially when cutting ferrous alloys using oxygen as an assist gas, laser cut quality cannot be easily predicted; therefore, the quality inspection of the laser cut is performed by off line inspections of the edges of the metal by skilled operators. This methodology is carried out after the process and thus cannot maintain a good quality if the process performance is out of control. Therefore, the objective of the research project is to qualify and develop a sensor system that ensure fault recognition online and can automatically control the laser metal cutting process to achieve good quality cut. For the realization of this objective the following has been done: - study the relationship between process parameters and cut quality characteristics; - identify the best sensors that can be used to monitor the process; - design and develop an experimental setup to test the proposed sensors; - collect and analyze data from the proposed sensors and correlate them to specific cut quality characteristics (process state variables); - develop direct relationships between the process signals and cut quality; - develop appropriate strategy for process control; - design and develop an integrated monitoring and control system; - test and evaluate the proposed system using simulation. In this study, a new technique for the determination of cut quality of sheet steels under the CO2 laser cutting process has been established. It is based on on-line detection and post-processing analysis of light radiation and acoustic emissions from the cut kerf. Determination of machining quality during cutting is best done through the measurement of surface roughness and kerf widths, as these are the two parameters that vary in successful through cuts. These two quality parameters can further be correlated to the two dominant process parameters of laser power and cutting speed. This study presents an analysis of acoustic emissions and reflected light for CO2 laser cutting of steel plates, and discusses their use for the estimation of cut quality parameters of kerf width and striation frequency for mild steel plates of 3mm, 5mm, 8mm, and 10mm thicknesses. Airborne acoustic and light signals are acquired with a microphone and a photodiode respectively, and recorded with a PC based data acquisition system in real time. The signals are then analyzed to establish a correlation between the signals obtained and the cut quality achieved. Experimental evidence shows that the energy levels of acoustic emission signals (RMS analysis) can be used to maintain the cutting process under steady state condition. On the other hand, the light intensity signal fluctuates with a frequency that corresponds to the frequency of striations formed on the cut surface; therefore it can be used to regulate cutting speed and laser power to obtain an optimum cutting condition and best cut quality. The validity of the proposed control strategy was tested experimentally by simulating the variations of cutting speed and examining their effect on the signals. So far, the prototype used for experimentation has been successful in providing correct information about cut quality in terms of striation frequency, and also about the state of the process where the microphone signal was successful in determining system failure or improper cutting conditions. A microprocessor based control system utilizing the PID control algorithm is recommended for the implementation of the control strategy. The implementation requirements of the proposed system for industrial use are then discussed. A new setup for the coaxial monitoring of CO2 laser cutting using a photodiode is proposed to enhance the quality of the signal and also to protect the photodiode from the harsh cutting environment. It is also proposed that an open control architecture platform is needed to enhance the integration of the proposed process control functions. Conclusions and future research directions towards the achievement of Autonomous Production Cell (APC) for the laser cutting process are then given.