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Dissertations / Theses on the topic 'Metal working'
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1
Nilsson, Maria. "Tribology in Metal Working." Licentiate thesis, Högskolan Dalarna, Materialteknik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:du-11730.
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This thesis focuses on the tribological performance of tool surfaces in two steel working operations, namely wire drawing and hot rolling. In all forming operations dimensions and surface finish of the products are of utmost importance. Forming basically includes three parts – forming conditions excluded – that may be changed; work material, tool and (possibly) lubricant. In the interface between work material and tool, the conditions are very aggressive with – generally or locally – high temperatures and pressures. The surfaces will be worn in various ways and this will change the conditions in the process. Consequently, the surface finish as well as the dimensions of the formed product may change and in the end, the product will not fulfil the requirements of the customer. Therefore, research and development in regard to wear, and consequently tribology, of the forming tools is of great interest. The investigations of wire drawing dies focus on coating adhesion/cohesion, surface characteristics and material transfer onto the coated steel both in laboratory scale as well as in the wire drawing process. Results show that it in wire drawing is possible to enhance the tribological performance of drawing dies by using a lubricant together with a steel substrate coated by a polished, dual-layer coating containing both hard and friction-lowering layers. The investigations of hot rolling work rolls focus on microstructure and hardness as well as cracking- and surface characteristics in both laboratory scale and in the hot strip mill. Results show that an ideal hot work roll material should be made up of a matrix with high hardness and a large amount of complex, hard carbides evenly distributed in the microstructure. The surface failure mechanisms of work rolls are very complex involving plastic deformation, abrasive wear, adhesive wear, mechanical and thermal induced cracking, material transfer and oxidation. This knowledge may be used to develop new tools with higher wear resistance giving better performance, lower costs and lower environmental impact.
2
Gast, Christopher van der. "Microbial dynamics of metal-working fluids." Thesis, University of Oxford, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.365323.
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Prince, Edmund Lee. "Fungal biodeterioration of synthetic metal working fluids." Thesis, University of Central Lancashire, 1988. http://clok.uclan.ac.uk/20019/.
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A survey was undertaken to determine the relative incidence of fungal biodeteriogens in contaminated in—service samples of synthetic and oil emulsion metal working fluids, and a list of isolates is submitted. A technique for assessing the concentration of surface—active components of both synthetic and oil emulsion metal working fluids is described. Results obtained using this technique provided evidence of surfactant depletion in oil emulsion fluids as a result of growth of a mixed fungal inoculum, but this effect was not recorded when these isolates were grown in synthetic fluids. Synthetic metal working fluds of known composition were formulated and the ability of selected fungal isolates to utilise both these fluids and the individual components thereof as sole sources of carbon and nitrogen was assessed. The metal working fluid components triethanolamine and diethanolamine borate were found to be readily available nutrient sources for growth of the isolates, the extent of growth being limited by the availability of carbon rather than nitrogen. Varying the initial pH of the medium was found to have no significant effect upon the extent of growth recorded at initial pH values of 7.0, 8.0 and 9.0. The use of respirometric techniques provided evidence to suggest that some of the enzymes involved in the fungal degradation of synthetic metal working fluid components might be inducible. The effect of fungal growth upon the composition of the complete synthetic metal working fluids was determined using the techniques of nuclear magnetic resonance spectroscopy and gas—liquid chromatography linked mass spectrometry. Results obtained using these techniques also provided evidence of the depletion of the triethanolamine and diethanolamine borate components of the complete fluids as a result of fungal growth.
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Nilsson, Annika. "Modelling and simulation of metal working processes /." Luleå, 2000. http://epubl.luth.se/1402-1544/2000/41/index.html.
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Takahashi, Shinya. "Infusing machine made objects into traditional metal working." Virtual Press, 2005. http://liblink.bsu.edu/uhtbin/catkey/1313951.
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Living in this high-technology era, the computer is pervasive item in modern life. The creation of jewelry pieces has also been affected by machines controlled by computers. If machines create millions of identical jewelry pieces, what will make the difference between creative and mundane pieces? This creative project is to pursue the use of machine-made objects and produce creative pieces of jewelry. Also, in order to gain practical skills and enhance my design skills, I designed many pieces of jewelry with 3-D software.Department of Art
6
Pisoni, Attilio C. (Attilio Carlo). "A constitutive model for friction in metal-working." Thesis, Massachusetts Institute of Technology, 1992. http://hdl.handle.net/1721.1/12620.
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Wang, Xifan. "Ideal Process Design Approach for Hot Metal Working." University of Dayton / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1375222977.
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Burton, Clare. "Respiratory disease in workers exposed to metal working fluids." Thesis, University of Sheffield, 2015. http://etheses.whiterose.ac.uk/8269/.
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The largest UK outbreak of respiratory disease in metalworking fluid (MWF) exposed workers (Powertrain) led to a heightened awareness of the health hazards associated with MWF. A literature review identified 29 outbreaks of ill health associated with MWF exposure with a peak incidence between 1996 and 2000. Microbial contamination was suspected but no unifying causative agent could be found. Six different case definitions for extrinsic allergic alveolitis (EAA) were indentified, only one of which was validated. The process of developing an evidence based case definition for MWF-EAA required the identification of a group of patients with unequivocal MWF associated EAA. The Powertrain database (created at the time of the outbreak and subsequent follow up appointments) was utilised and an Expert Panel of five occupational lung disease consultants concluded that there was sufficient clinical evidence to diagnose 14 workers as definite cases of EAA. By calculating the positive predictive value of the data points relevant to a diagnosis of EAA combined with knowledge and experience of previous EAA diagnostic criteria, it was possible to develop a new evidence-based EAA diagnostic score (the MWF EAA Score). The MWF EAA Score was applied to the Powertrain data demonstrating agreement with the Expert Panel opinion in over 80% of the cases with a greater number of workers correctly classified than with other published diagnostic criteria1. The score was also applied to previously published case series of workers diagnosed with MWF EAA, in order to externally validate the new EAA rating system. The MWF EAA Score appeared to perform well and there was sufficient data provided in almost half of these published cases indicating that the MWF EAA Score would have shown agreement. This scoring system is a simple and reproducible tool and provides an evidence-based case definition suitable for use in future UK outbreaks.
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Blake, David Matthew. "Cold working effects on mechanical properties in sheet metal joining for automotive applications." Online access for everyone, 2006. http://www.dissertations.wsu.edu/Thesis/Fall2006/d_blake_112706.pdf.
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Rimkus, Wolfgang. "Simulation and optimisation of the Interior High Pressure (IHP) manufacturing process using the Finite Element Method (FEA)." Thesis, University of Wolverhampton, 2000. http://hdl.handle.net/2436/90558.
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Liu, Chun. "Modeling of water and lubricant sprays in hot metal working." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1196091214.
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Miller, Duncan. "Iron age metal working at the Tsodilo Hills, Northwestern Botswana." Doctoral thesis, University of Cape Town, 1992. http://hdl.handle.net/11427/18277.
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This study documents the metal working technology employed at two major Iron Age archaeological sites in southern Africa. The research involved the description and analysis of two large metal working assemblages with a total of 2922 metal artefacts, fragments of ore, and slag, from the sites of Divuyu (6th 8th century AD) and Nqoma (7th - 10th century AD, with a later 17th - 19th century AD occupation) in the Tsodilo Hills, northwestern Botswana. This is the first systematic description and metallographic analysis of a large collection of Early Iron Age metal artefacts from southern Africa. The artefacts were small, mainly delicate items of copper and iron jewellery, and tools possibly used in their manufacture. They were classified, described, and sampled selectively for metallographic, petrographic, and chemical analysis. Seventy artefacts were studied in detail, from which the fabrication technology employed at these sites was reconstructed. During the Early Iron Age forging, and probably also smelting, of iron took place at both sites. The smelting products were inhomogeneous iron and steel, with typical fayalitic slag, characteristic of indigenous bloomery iron production. The forging was done in an oxidising hearth and the technique used was poor, with no deliberate control over carbon content, the mechanical properties of the steel, or heat treatment other than annealing. Fabrication involved hammering square wire and flat sheets, which were cut into strips for beads, clips, chains, and fibre-cored wound ornaments. Numerous finger rings were made from crude round iron wire. Copper was worked in the same way, generally leaving the metal in its annealed state. Significant chemical variation in the copper artefacts and iron slag inclusions indicated that diverse ore sources were involved. There were stylistic similarities between individual artefacts from the Tsodilo Hills and Early Iron Age material from the Upemba Depression in Zaire, as well as with a copper chain from Broederstroom in the Transvaal. Comparison of the fabrication technology with Later Iron Age material suggested that local indigenous iron and copper working technology has changed little since its introduction in southern Africa.
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GRESSEL, MICHAEL GERARD. "COMPARISON OF MIST GENERATION OF FLOOD AND MIST APPLICATION OF METAL WORKING FLUIDS DURING METAL CUTTING." University of Cincinnati / OhioLINK, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=ucin990120958.
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Goniwe, Nicholas Sandisile. "Simulation of a multi-stage forming process to investigate failure in the formed part." Thesis, Cape Peninsula University of Technology, 2016. http://hdl.handle.net/20.500.11838/2518.
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Thesis (MTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2016.The purpose of this study is the optimisation of the stamping analysis process in order to investigate the possible reasons for the part failure. (Altan & Vasquez, 2000) have conducted similar research to optimise a forming process. However, they focussed on dies for a forging process and in this study, we are looking at cold forming and this study is also different in that we are trying to reduce the number of stages while maintaining the formability. Formability is based on the dimensional conformance of the final part with additional criteria being the thinning, appearance of wrinkling, dynamic effects leading to the localisation of strain, cracking and residual stress. A numerical modelling procedure that is close enough to the real process is used to investigate the effects of changes in the frictional contact that would correspond to lubrication and also the effect of adding draw beads to the forming tools to change the frictional contact. We also investigated the effect of using a different material in terms of meeting the design requirements. Experimental results for comparison are available for certain of the stamping processes investigated that were tested in pre-production. The finite element simulation is used to account for all residual thinning, stress and strain of the multi-stage forming process to ensure optimum thickness changes of the sheet at each stage. The variations of material and manufacturing parameters are established to accurately predict the behaviour of this specific forming process. The material model required to meet physical experiments is deduced from the results of standard tensile tests and fitted to the Hill’s 48 Law for Work Hardening. The commercial packages Ls-Dyna with Dynaform and Pam-Stamp software are used for the simulation to produce 2 results for comparison.
15
Oyekanmi, B. O. "The determination of strain distributions in forgings." Thesis, University of Leeds, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.383928.
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Palkar, Ashish Yudhishthir Harris Daniel K. "An experimental investigation of liquid metal MHPs." Auburn, Ala., 2007. http://repo.lib.auburn.edu/2007%20Fall%20Theses/Palkar_Ashish_26.pdf.
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Palaniswamy, Hariharasudhan. "Determination of process parameters for stamping and sheet hydroforming of sheet metal parts using finite element method." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1195621470.
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Darbyshire, G. "Pre-Roman iron tools for working metal and wood in southern Britain." Thesis, Cardiff University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.337305.
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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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Sabih, Amar. "Workability study for adiabatic shear band phenomenon in the steel cold heading process." Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=111856.
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The motivation behind this study is the lack of specialized analysis regarding internal failure caused by the adiabatic shear hand (ASB) phenomenon in the cold-headed products. Its aim was to present an integrated workability study to improve and assist cold-heading (CH) multistage design procedures to replace the current design rules of thumb, as they are neither effective nor adequate in fulfilling the needs of the new developments in the rapidly expanding CH industry.To achieve these goals, a comprehensive testing methodology and FE modeling, implemented within ABAQUS/Explicit, were established. This methodology includes an instrumented Drop Weight Compression Test (DWCT) tower equipped with a guided pocket die-set configuration capable of developing internal failure at different stages of ASBs and integrated metallographic inspection techniques. A validated FE model of the DWCT and guided pocket die-set configuration was a valuable tool in establishing the failure criteria and indicating the workability limits.
A detailed experimental and FE study for the ASB stages in the CH process was introduced to uncover the affect of different parameters controlling the failure mechanisms within the ASBs in the CH process. This study investigated the effect of the thermal, geometric and the material flow softening and hardening mechanisms affecting ASB evolution. Moreover, a detailed metallurgical and FE study of the internal ductile and Transformed Adiabatic Shear Band (TASB) failures caused by the ASB phenomenon in DWCT was conducted.
Three ductile failure criteria were introduced to predict the initiation and location of the internal ductile failure in the ASBs. One TASB failure criteria was introduced to predict the phase transformation to undesirable brittle martensite. These failure criteria were employed to establish integrated workability methodologies to indicate the objective workability limits.
Applying these workability methodologies on multistage CH FE models showed that these methodologies are an efficient tool to predict the damage levels and failure initiation locations within the cold-headed bolts. Moreover, these methodologies were successful in optimizing the die designs in order to reduce damage levels.
21
Wong, Kai-wing. "A CAD/CAM system for sheet metal blanking dies /." [Hong Kong : University of Hong Kong], 1991. http://sunzi.lib.hku.hk/hkuto/record.jsp?B13204841.
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Ercanli, Levent. "The Examimnation Of Metal Working Technology In Kultepe In Assyrian Trade Colonies Period." Phd thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614269/index.pdf.
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Metal played important role in the social and economic development of societies since its discovery. It is so important that the some part of humankind historical development were designated by the type of metal which was extensively used depending upon the level of technology of that period enabling the processing of metal like bronze age and iron age.
In this frame, the rich metal deposits of Anatolia made this region a very important metal working and civilization center.
Kültepe where it was the center of the trade organization in Anatolia realized between Assur and Anatolia during 1945-1730 B.C called Assyrian Trade Colonies Period was one of the most important metal working center of Anatolia at that period. In this thesis, it is aimed to make a contribution to understand the metal working technology in Kü
ltepe by examining the uncovered metal artifacts dated to that period. For this purpose, the metal artifacts uncovered from Kü
ltepe Ancient Site belonging to Colonies Period which are exhibited in the Anatolian Civilization Museum were examined by portable XRF (PXRF) to obtain the quantity of elements that constituted the artifacts without giving any harm to the artifact. Besides the examination of exhibited artifacts in the Anatolian Civilization Museum, the uncovered metal artifact parts belonging to Colonies Period which are not suitable for exhibition and separated for studying were examined by energy dispersive X-ray unit of scanning electron microscope for elemental analysis and by X-ray diffraction for the analysis of minerals. The microstructures of artifacts were examined by scanning electron microscope and optical microscope for revealing the operations on metal applied by ancient metalsmith. In addition to analysis mentioned above, in order to make a contribution to understand the copper trade between Kü
ltepe and its environs lead isotope analysis of some samples from the separated metal artifacts for studying was also performed. As a result of all those analyses, it was concluded that Kü
ltepe ancient metalsmiths in Colonies Period had the knowledge to smelt the copper and to pour molten metal into a mold to produce an object of desired shape. Moreover, they also discovered that the addition of some elements to copper hardens the structure. In this frame the bronze to be obtained by deliberately adding of tin to copper was attained. In addition, they were aware of shaping the casted object by hammering. In the meantime, they had the knowledge of heat treatment that allows them forging the object many times till giving the desired shape without causing the fracture in the structure.
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Moetakef-Imani, Behnam. "Model based die cavity machining simulation methodology /." *McMaster only, 1997.
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Livelli, Mark Andrew. "Providing flow parameters for approximate die design models and the improvement and verification of those models using CFD analysis /." Online version of thesis, 2010. http://hdl.handle.net/1850/12222.
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Holdgate, Nicholas Michael David. "Peen mechanics in the shot peening process." Thesis, University of Cambridge, 1994. https://www.repository.cam.ac.uk/handle/1810/251562.
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Fraser, Darren T. "Soldering in high pressure die casting and its prevention by lubricant and oxide layers /." [St. Lucia, Qld.], 2000. http://adt.library.uq.edu.au/public/adt-QU20010830.163828/.
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Grobaski, Thomas C. "Preliminary research for the development of a hot forging die life prediction model." Ohio : Ohio University, 2004. http://www.ohiolink.edu/etd/view.cgi?ohiou1102695461.
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Glasse, Benjamin [Verfasser]. "Monitoring of Metal Working Fluid Emulsion Quality by in-process Light Spectroscopy / Benjamin Glasse." Berlin : epubli GmbH, 2015. http://d-nb.info/1074331206/34.
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Buers, Katy Louise Mary. "A treatment process for the degradation of metal-working fluids using mixed microbial cultures." Thesis, University of Kent, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.242930.
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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.
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黃啓榮 and Kai-wing Wong. "A CAD/CAM system for sheet metal blanking dies." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1991. http://hub.hku.hk/bib/B31210594.
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Frieman, Catherine. "Skeuomorphs and stone-working : Elaborate lithics from early metal-using era in coastal northwest Europe." Thesis, University of Oxford, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.533810.
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Arone, Miles. "Development of a tool management system for use in a mass production metal working facility." Thesis, Massachusetts Institute of Technology, 1993. http://hdl.handle.net/1721.1/12324.
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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1993, and Thesis (M.S.)--Massachusetts Institute of Technology, Sloan School of Management, 1993.Includes bibliographical references (leaves 148-149).
by Miles Arone.
M.S.
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Kotze, Burger Adriaan. "The development of a design protocol for production of high speed coining dies." Pretoria : [s.n.], 2006. http://upetd.up.ac.za/thesis/available/etd-07032006-151623/.
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Endres, Matthew J. "Spray cooling of steel dies in a hot forging process." Link to electronic thesis, 2002. http://www.wpi.edu/Pubs/ETD/Available/etd-0904102-141539.
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Thompson, J. Kyle. "Study of powder metal press and sinter process and its tool wear." Master's thesis, Mississippi State : Mississippi State University, 2007. http://library.msstate.edu/etd/show.asp?etd=etd-07062007-113955.
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Itakura, Tomoya. "Synthesis and Characterization of Proton Conducting Coordination Polymers Working under Low-humidity Condition." Kyoto University, 2017. http://hdl.handle.net/2433/217993.
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Boysen, Christopher J. "An analysis and development of controls for exposures to maintenance personnel working on the plasma metal etchers." Online version, 1998. http://www.uwstout.edu/lib/thesis/1998/1998boysenc.pdf.
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Yang, Lin. "Physiothermodynamics of lubricant application to hot die surfaces." Connect to this title online, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1117551258.
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Thesis (Ph. D.)--Ohio State University, 2005.Title from first page of PDF file. Document formatted into pages; contains xviii, 178 p.; also includes graphics (some col.) Includes bibliographical references (p. 173-178). Available online via OhioLINK's ETD Center
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Chitti, Babu Surendra. "Development of tailored preform processing technology for net-shape manufacturing of large monolithic structures." Diss., Columbia, Mo. : University of Missouri-Columbia, 2007. http://hdl.handle.net/10355/4861.
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Thesis (Ph. D.)--University of Missouri-Columbia, 2007.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on January 31, 2008) Vita. Includes bibliographical references.
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Chen, Zhong. "Cutting fluid aerosol generation and dissipation in machining process : analysis for environmental consciousness." Diss., Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/17929.
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Borsetto, Francesca. "Tribological performance of environmentally friendly solid lubricant coatings for sheet metal forming." Doctoral thesis, Università degli studi di Padova, 2010. http://hdl.handle.net/11577/3427080.
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In a society becoming more and more conscious of the effect of human activities on environment, it is not possible to neglect impacts caused by manufacturing. Not only environmental but particularly economical and legislative reason oblige industry to respond. Besides, it must be a technological objective to optimize production towards environmental compatibility or cleanness respectively.
Sheet metal forming is assessed to consume quite few energy, related to the weight of a finished component, and to yield a high degree of material efficiency. However due to the earth’s decreasing resources and the pollution caused by energy and material consumption further reductions of consumptions are required.
The transformation of energy, material and supplies into a finished or semi-finished piece is only one aspect of metal forming. Besides the piece to be produced, all production steps of material’s pre-treatment, forming and post-treatment also produce unwanted and more or less harmfull residual materials and emissions. referring to the forming step oil based lubricants play a key role as they are environmentally hazardous and pose a danger both directly to the production personnel, which are in daily contact with the products. In addition they force to use unhealthy degreasing agents to remove the oil from the formed parts. The possible strategies for how to handle residual lubricants are:
• disposal
• recycling
• reduction
• substitution
• avoidance
Nowadays, the disposal of the exhausted oil is still a very widespread method even if it does not represent an ecologically nor economically attractive solution for the future, but reduction and especially substitution are required wherever possible. Pursuing the reduction/avoidance strategy, in recent years different types of solid lubricant coatings deposited mainly on the tool side have been proposed and their frictional behaviour investigated. Scientific literature presents results from several tests performed on these materials through commercially available friction testers, but they usually reproduce testing conditions far from the real process ones.
Therefore, the objective of the present work is to investigate the friction behaviour of three different types of solid lubricant coatings deposited either on the tool side or on the sheet metal side, under process conditions.
Two different case studies have been analyzed: deep drawing of stainless sheets and hot stamping of quenchable boron high strength steels.
With respect to the first tribological system the friction coefficient µ is determined as function of the main process parameters: normal pressure, sliding speed, tool and sheet metal specimen temperatures by means of an ad hoc experimental device, designed and set-up during the Phd period at The Department of Manufacturing, University of Padova. The results obtained for two different inhorganic coatings (tool side) and two types of organic coated sheet were compared with the performance of a deep drawing conventional oil (considered as reference). While the inorganic coated dies performed worse than the non coated ones (due especially to their surface morphology) the organic film coated specimens showed a high potential to perform dry sheet metal working operations being their coefficient of friction comparable with the one of the traditional oil.
In the case of the hot stamping process Al-Si coated high strength steel sheet where studied in terms of the film evolution with thermal parameters. The coating tribological performance as function of testing temperature, normal pressure, sliding speed tool surface roughness was investigated by means of high temperature pin on disc test. As main result it was found that the interaction between the testing temperature and the normal pressure did influence the friction at the sheet metal die interface thus allowing an optimization of the process parameters.In una società che diventa sempre più consapevole delle conseguenza che l’attività umana ha sull’ambiente, non è possibile ignorare l’impatto dovuto alle aziende manifatturiere. Queste ultime devono rispondere non solo a delle esigenze ambientali ma anche a degli obblighi di tipo economico e legislativo. Nello specifico, lo stampaggio di lamiera viene considerato come un processo che consuma non poca energia se viene considerato il peso del componente finito, al tempo stesso si tratta di un processo caratterizzato da un livello elevato di efficienza per quanto riguarda l’utilizzo di materia prima. Nonostante ciò l’esaurirsi delle risorse presenti in natura ed il livello preoccupante di inquinamento causati dal consumo di energia e di materia prima impone un’ulteriore riduzione dei consumi. La trasformazione di energia, materia prima e utenze in un prodotto finito o semi-finito è solo un aspetto dello stampaggio di lamiera. Oltre al pezzo da realizzare, tutte le fasi di produzione dal pre-trattamento del materiale, alla formatura, al post-trattamento producono anch’esse materiali residui o emissioni non voluti o pericolosi. Con particolare riferimento alla fase di formatura i lubrificanti di tipo liquido giocano un ruolo fondamentale essendo per la maggior parte nocivi nei confronti dell’ambiente e pericolosi da utilizzare da parte del personale. In aggiunta sono necessari agenti sgrassanti, solitamente nocivi, per pulire il pezzo finito. Al fine di ridurre l’impatto ambientale degli olii lubrificanti, e possibili strategie sono: • smaltimento • reciclaggio • riduzione • sostituzione • eliminazione Attualmente la pratica più diffusa è quella relativa allo smaltimento anche se non rappresenta una soluzione vantaggiosa né dal punto di vista economico né dal punto di vista ecologico; la riduzione ed ancora di più l’eliminazione dei lubrificanti liquidi dovrebbero essere perseguite laddove possibile. Sostenendo una politica di eliminazione negli ultimi anni sono state proposte diverse tipologie di rivestimenti solidi atti alla riduzione dell’attrito nello stampaggio di lamiera. In letteratura si trovano diversi risultati sperimentali relativi al loro comportamento tribilogico, in condizioni però tendenzialmente diverse da quelle tipiche di processo. Il presente lavoro di tesi si pone pertanto come obiettivo la caratterizzazione tribologica, in condizioni di processo, di tre sistemi di lubrificazione di tipo solido. Sono stati presi in considerazione due diversi casi industriali, imbutitura di acciaio inossidabile e stampaggio a caldo di acciaio altoresistenziale al boro. Con riferimento al primo sistema tribologico si è determinato il coeffciiente d’attrito in funzione di pressione normale, velocità di scorrimento, temperatura sia dell’utensile che della lamiera tramite test simulativo di tipo trip drawing. L’attrezzatura sperimentale in grado di realizzare tale tipologia di test è stata interamnente progettata e realizzata durante il periodo di dottorato presso i laboratori del DIMEG, Università di Padova. I risultati ottenuti per i due rivestimenti di tipo inorganico (CrN, CrN-DLC) depositati sul lato stampo sono stai peggiori di quelli ottenuti con gli stampi non rivestiti e lubrificati solo con olio. Ciò è stato probabilmente dovuto alla morfologia della superficie rivestita che va ottimizzata una volta effettuato il deposito del rivestimento stesso. Per quanto riguarda i rivestimenti organici, uno in particolar modo, ha dimostrato di essere un ottimo candidato per operazioni di stampaggio a secco dal momento che presenta un coefficiente d’attrito paragonabile a quello dell’olio. Con riferimento invece al sistema tribologico presente nelle operazioni di hot stamping, si è inizialmente studiata l’evoluzione sia chimica che morfologica del rivestimento Al-Si (depositato sulla lamiera) con i parametri termici di proceeso. Quindi si è analizzato il comportamento tribologico dello stesso in funzione di parametri quali la temperatura di test della lamiera, la pressione normale, la velocità di strisciamento e la rugosità dello stampo. Si è messo in evidenza come l’interazione tra pressione normale e temperatura abbiano un’influenza significativa sull’attrito all’interfaccia lamiera/stampo permettendo così un’ottimizzazione dei parametri di processo.
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Sui, Ning. "Synthesis, characterization and optical properties of hybrid nanoparticles working with plasmon-fluorescence coupling." Phd thesis, Ecole Centrale de Lyon, 2012. http://tel.archives-ouvertes.fr/tel-00781927.
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L'exaltation de fluorescence par un métal est de plus en plus utilisée pour augmenter la sensibilité de détection dans les systèmes utilisant la fluorescence. Au cours de ce travail de thèse, nous avons étudié ce phénomène dans des nanoparticules hybrides Métal@SiO2 possédant des émetteurs de fluorescence immobilisés sur la silice. Dans un premier temps, nous avons élaboré les nanoparticules cœur-coquille Métal@SiO2 (Métal = Au ou Ag) en utilisant différentes méthodes et en les comparant pour choisir la plus adaptée selon le diamètre du cœur métallique. Dans un deuxième temps, nous avons étudié les propriétés de fluorescence exaltée des nanoparticules hybrides. Deux types d'émetteurs de fluorescence ont été sélectionnés : des nanoparticules semi-conductrices (SiC) et des fluorophores organiques (cyanine 3 et fluorescéine). Après fonctionnalisation de la silice, les émetteurs de fluorescence ont été greffés à la surface des nanoparticules Métal@SiO2. L'exaltation de leur fluorescence a été analysée en fonction de leur densité surfacique, de leur distance par rapport au cœur métallique (fixée par l'épaisseur de silice), du diamètre du cœur métallique et de la longueur d'onde d'excitation. Le facteur d'exaltation le plus important (de l'ordre de 103) a été obtenu avec une faible épaisseur de silice (10 nm) pour les nanoparticules de SiC dont le rendement quantique intrinsèque est très faible (inférieur à 1%). Enfin, la surface de nanoparticules hybrides a été fonctionnalisée avec des nanoparticules d'oxyde de fer de manière à obtenir une combinaison de propriétés optiques (fluorescentes et plasmoniques) et magnétiques à l'intérieur d'une même nanoparticule hybride.
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Dingle, Matthew, and mikewood@deakin edu au. "Elastic behaviour in mechanical draw presses." Deakin University. School of Engineering and Technology, 2001. http://tux.lib.deakin.edu.au./adt-VDU/public/adt-VDU20051017.150247.
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This thesis explores the elastic behaviour of the mechanical double action press and draw die system commonly used to draw sheet metal components in the automotive industry. High process variability in production and excessive time spent in die try-out are significant problems in automotive stamping. It has previously been suggested that the elastic behaviour of the system may contribute to these problems. However, the mechanical principles that cause the press system to affect the forming process have not been documented in detail. Due to a poor understanding of these problems in industry, the elasticity of the press and tools is currently not considered during the die design. The aim of this work was to explore the physical principles of press system elasticity and determine the extent to which it contributes to problems in try-out and production. On the basis of this analysis methods were developed for controlling or accounting for problems during the design process.
The application of frictional restraining force to the edges of the blank during forming depends on the distribution and magnitude of the clamping force between the binders surfaces of the draw die. This is an important control parameter for the deep drawing process. It has been demonstrated in this work that the elasticity of the press and draw die can affect clamping force in two ways. The response of the press system, to the forces produced in the press during forming, causes the magnitude of clamping force to change during the stroke. This was demonstrated using measured data from a production press. A simple linear elastic model of the press system was developed to illustrate a definite link between the measured force variation and the elasticity of the press and tools. The simple model was extended into a finite element model of the complete press system, which was used to control a forming simulation. It was demonstrated that stiffness variation within the system could influence the final strains in a drawn part. At the conclusion of this investigation a method is proposed for assessing the sensitivity of a part to clamping force variation in the press during die design. A means of reducing variation in the press through the addition of a simple linear spring element is also discussed.
The second part of the work assessed the influence of tool structure on the distribution of frictional restraining forces to the blank. A forming simulation showed that tool stiffness affects the distribution of clamping pressure between the binders. This was also shown to affect the final strains in a drawn part. However, the most significant influence on restraining force was the tendency of the blank to increase in thickness between the binders during forming. Using a finite element approximation of the try-out process it was shown that the structure of the tool would also contribute to the problems currently experienced in try-out where uneven contact pressure distributions are addressed by manually adjusting the tool surfaces.
Finally a generalised approach to designing draw die structures was developed. Simple analysis methods were combined with finite element based topology optimisation techniques to develop a set of basic design guidelines. The aim of the guidelines was to produce a structure with uniform stiffness response to a pressure applied at the binder surface.
The work concludes with a recommendation for introducing the methods developed in this thesis into the standard production process.
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Фесенко, А. "Металлоискатель." Thesis, Сумский государственный университет, 2014. http://essuir.sumdu.edu.ua/handle/123456789/38883.
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Pires, Gisele Puime. "Estudo sobre a estampabilidade, no estado solido, da liga de aluminio A5052 tixofundida, e viabilidade da sua tixoestampagem." [s.n.], 2005. http://repositorio.unicamp.br/jspui/handle/REPOSIP/263647.
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Orientador: Maria Helena RobertTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica
These (docteur) - Universite de Savoie, Ecole Superiore D'Ingenieurs D'Annecy, France
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Resumo: Este trabalho apresenta estudo sobre a viabilidade da estampagem, no estado semisólido, de chapas da liga A5052. Inicialmente, para a obtenção de chapas tixofundidas, chapas comerciais laminadas foram submetidas ao processo de fusão parcial controlada, variando-se os parâmetros tempo e temperatura, com o objetivo de analisar a estampabilidade das chapas no estado sólido. Os parâmetros utilizados foram: fusão parcial a 627°C por 5 e 10 minutos, e 634°C, por 5 e 15 minutos, em chapas com 0,8 mm; fusão parcial a 624°C por 5 e 10 minutos, e 631°C por 5 e 15 minutos, em chapas com 2,0 mm; e fusão parcial a 625, 630 e 635°C por 15 minutos em chapas de 4,0 mm de espessura. As chapas foram caracterizadas com relação à microestrutura, sendo observada homogeneidade estrutural em toda a chapa. Também foram caracterizadas quanto às propriedades mecânicas, sendo que o material tixofundido (obtido por fusão parcial) apresentou diferenças significativas em relação ao material laminado. Para a caracterização da estampabilidade do material, foram feitos ensaios de Erichsen e obtidas curvas limite de conformação de chapas nos estados laminado, recozido e tixofundido, utilizando o método Marciniak e um método de análise de imagens para a obtenção das deformações principais da liga nos diferentes estados. Os resultados mostraram que o material tixofundido apresenta formabilidade semelhante à do material recozido. Foi buscada a caracterização do arranjo espacial de glóbulos em pastas tixofundidas; os resultados mostraram a presença de aglomerados tridimensionais de partículas com evidente interação entre elas, indicando a possibilidade da estrutura suportar esforços de tração. Portanto, para estudos da viabilidade de tixoestampagem, foi construída matriz com geometria tal a apresentar condições severas de conformação. As chapas foram tixoestampadas (temperaturas acima da solidus) e comparadas com chapas estampadas a quente. Observou-se que a tixoestampagem é um processo perfeitamente viável, levando a excelentes resultados de acabamento da peça e redução da força necessária para a obtenção do produto
Abstract: This work presents an analysis of the viability of drawing A5052 sheets in the semisolid state. Initially, to produce thixocast sheets, rolled commercial sheets were submitted to partial melting by different temperatures and holding times, to analyse the sheets draw ability in the solid state. The parameters utilised were: 627°C for 5 and 10 minutes, and 634°C, for 5 and 15 minutes, in sheets of 0,8 mm; 624°C for 5 and 10 minutes, and 631°C for 5 and 15 minutes, in sheets of 2,0 mm; and 625, 630 and 635°C for 15 minutes in sheets of 4,0 mm thickness. The sheets had their microstructure characterised; results showed high homogeneity of the structure throughout the test piece. Mechanical properties of the thixocast material (obtained by partial melting) were also characterised, showing significant differences when compared to the rolled condition. For drawing ability characterisation, Erichsen tests were performed and forming limit diagrams of the sheets in the rolled, annealed and thixocast states were obtained, using Marciniak's technique and image analysis to obtain the main deformations of the alloy in the different conditions. Results showed that the thixocast material shows good formability, similar to the annealed material. Characterisation of the spatial structure of thixocast slurry showed the presence of tridimensional agglomerates of globular solid particles, with evident interaction among globules, indicating the possibility of the structure to stand tensile stresses. Therefore, for thixodrawing tests, a die was especially designed to impose severe flow conditions. The sheets were formed by thixodrawing (temperatures above the solidus) and compared to hot drawing tests. It was observed that thixodrawing is a perfectly viable process, requiring lower forces than conventional solid processing and resulting in excellent finishing products
Doutorado
Materiais e Processos de Fabricação
Doutor em Engenharia Mecânica
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Setia, Diarta. "Small and Medium Sized Enterprise(SME) in Social and Political Context： A Case of Metal-working Industry in Indonesia 1980s-2015." Kyoto University, 2018. http://hdl.handle.net/2433/235976.
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Shirgaokar, Manas. "Technology to Improve Competitiveness in Warm and Hot Forging: Increasing Die Life and Material Utilization." Columbus, Ohio : Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1205347635.
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Gonçalves, Neto Luiz Maurício [UNESP]. "Aplicação de fluido de corte em quantidades reduzidas para usinagem do aço SAE 52100 no processo de retificação centerless de passagem." Universidade Estadual Paulista (UNESP), 2013. http://hdl.handle.net/11449/106658.
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000722680.pdf: 3376023 bytes, checksum: 9612a64fd3199196c204263b3922817d (MD5)A presente tese propõe dar uma contribuição para o estudo de aplicação de fluido de corte no processo de retificação centerless de passagem, comparando os efeitos causados em termos de integridade da peça retificada entre a técnica convencional e a técnica aprimorada desenvolvida para o uso racional dos fluidos de corte. As condições testadas foram as seguintes: retificação centerless de passagem utilizando rebolo de corte convencional (C120TB24), três condições de lubrirefrigeração, bocal convencional (BC), bocal multitubular utilizando emulsão (BME) e bocal multitubular utilizando simultaneamente emulsão e ar comprimido (BMEA). Vazão do ar comprimido 170 L/min, vazões da emulsão: 10 L/min, 20 L/min, 30 L/min e 40 L/min e remoção de material de 0,03 mm e 0,10 mm. As variáveis de saída estudadas foram a rugosidade da superfície retificada, o desvio de circularidade e a tensão residual. Além disso, foram realizadas análise metalográfica, análise por partículas magnéticas e ataque químico com ácido nítrico da superfície retificada a fim de identificar a ocorrência de danos térmicos. Em relação às três técnicas de aplicação de fluido de corte utilizados (BC, BME e BMEA) no processo de retificação centerless passagem, em geral, observou-se um melhor desempenho com a utilização do novo conceito de bocal multitubular desenvolvido. As melhores condições de retificação foram observadas utilizando o BMEA para as vazões de 30 L/min e 40 L/min e com o BME para vazão de 30 L/min, removendo 0,03 mm de material. Para essas condições o processo foi capaz de garantir a integridade das peças, pois não apresentam danos térmicos às superfícies retificadas e mantiveram-se os valores dos desvios de circularidade e rugosidade superficial recomendados para o processo de retificação. O método convencional (BC)...
This work aims to contribute to the study and application of cutting fluid in the process of through-feed centerless grinding, comparing the effects in terms of workpiece integrity between the conventional technique and the improved technique developed for the rational use of cutting fluids. The test conditions were as follows: through-feed centerless grinding using silicon carbide resinoid grinding wheel (C120 TB24), three conditions of lubri-refrigeration, conventional nozzle (BC), multi-tube nozzle with emulsion (BME) and multitube nozzle with emulsion and compressed air simultaneously (BMEA). Compressed air flow rate 170 L/min, emulsion flow rate: 10 L/min, 20 L/min, 30 L/min, 40 L / min and material removal from 0,03 mm to 0,10mm. The output variables studied were the roughness of the ground surface, roundness deviation and residual stress. Additionally, metallographic analysis were performed as well as chemical attack with nitric acid on the ground surface in oder to identify the occurrence of thermal damage. Regarding the three techniques of cutting fluid application (BC, BME and BMEA0 in the process of through-feed centerless grinding, in general we observed a better performance when using the new concept of developed multi-tube nozzle. The best grinding conditions were observed using BMEA for the flow ratesn of 30 L/min and 40 L/min and with BME for the rate of 30 L / min, removing 0,03 mm of material. Fo these conditions the process was able to ensure workpiece integrity, since there were not thermal damage to the surface that were ground and the deviation values of roundness and surface roughness recommended for the grinding process were kept. The conventional method (BC) showed thermal damage in the layer that was ground for all conditions tested and the residual stress values of the ground... (Complete abstract click electronic access below)
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Gonçalves, Neto Luiz Maurício. "Aplicação de fluido de corte em quantidades reduzidas para usinagem do aço SAE 52100 no processo de retificação centerless de passagem /." Bauru, 2013. http://hdl.handle.net/11449/106658.
Full textAbstract:
Orientador: Eduardo Carlos BianchiBanca: Sandro Donnini Mancini
Banca: Rosemar Batista da Silva
Banca: Amauri Hassui
Banca: Manoel Cleber de Sampaio Alves
O Programa de Pós Graduação em Ciência e Tecnologia de Materiais, PostMat, tem caráter institucional e integra as atividades de pesquisa em materiais de diversos campi
Resumo: A presente tese propõe dar uma contribuição para o estudo de aplicação de fluido de corte no processo de retificação centerless de passagem, comparando os efeitos causados em termos de integridade da peça retificada entre a técnica convencional e a técnica aprimorada desenvolvida para o uso racional dos fluidos de corte. As condições testadas foram as seguintes: retificação centerless de passagem utilizando rebolo de corte convencional (C120TB24), três condições de lubrirefrigeração, bocal convencional (BC), bocal multitubular utilizando emulsão (BME) e bocal multitubular utilizando simultaneamente emulsão e ar comprimido (BMEA). Vazão do ar comprimido 170 L/min, vazões da emulsão: 10 L/min, 20 L/min, 30 L/min e 40 L/min e remoção de material de 0,03 mm e 0,10 mm. As variáveis de saída estudadas foram a rugosidade da superfície retificada, o desvio de circularidade e a tensão residual. Além disso, foram realizadas análise metalográfica, análise por partículas magnéticas e ataque químico com ácido nítrico da superfície retificada a fim de identificar a ocorrência de danos térmicos. Em relação às três técnicas de aplicação de fluido de corte utilizados (BC, BME e BMEA) no processo de retificação centerless passagem, em geral, observou-se um melhor desempenho com a utilização do novo conceito de bocal multitubular desenvolvido. As melhores condições de retificação foram observadas utilizando o BMEA para as vazões de 30 L/min e 40 L/min e com o BME para vazão de 30 L/min, removendo 0,03 mm de material. Para essas condições o processo foi capaz de garantir a integridade das peças, pois não apresentam danos térmicos às superfícies retificadas e mantiveram-se os valores dos desvios de circularidade e rugosidade superficial recomendados para o processo de retificação. O método convencional (BC)... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: This work aims to contribute to the study and application of cutting fluid in the process of through-feed centerless grinding, comparing the effects in terms of workpiece integrity between the conventional technique and the improved technique developed for the rational use of cutting fluids. The test conditions were as follows: through-feed centerless grinding using silicon carbide resinoid grinding wheel (C120 TB24), three conditions of lubri-refrigeration, conventional nozzle (BC), multi-tube nozzle with emulsion (BME) and multitube nozzle with emulsion and compressed air simultaneously (BMEA). Compressed air flow rate 170 L/min, emulsion flow rate: 10 L/min, 20 L/min, 30 L/min, 40 L / min and material removal from 0,03 mm to 0,10mm. The output variables studied were the roughness of the ground surface, roundness deviation and residual stress. Additionally, metallographic analysis were performed as well as chemical attack with nitric acid on the ground surface in oder to identify the occurrence of thermal damage. Regarding the three techniques of cutting fluid application (BC, BME and BMEA0 in the process of through-feed centerless grinding, in general we observed a better performance when using the new concept of developed multi-tube nozzle. The best grinding conditions were observed using BMEA for the flow ratesn of 30 L/min and 40 L/min and with BME for the rate of 30 L / min, removing 0,03 mm of material. Fo these conditions the process was able to ensure workpiece integrity, since there were not thermal damage to the surface that were ground and the deviation values of roundness and surface roughness recommended for the grinding process were kept. The conventional method (BC) showed thermal damage in the layer that was ground for all conditions tested and the residual stress values of the ground... (Complete abstract click electronic access below)
Doutor