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Tesi sul tema "Grinding"
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1
Agahi, Maryam. "Grinding polycrystalline diamond using a diamond grinding wheel". Access electronically, 2006. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20061114.150854/index.html.
Testo completo
2
Brown, Austin (Austin R. ). "Axially force limited grinding spindle for robotic grinding". Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/119966.
Testo completoAbstract (sommario):
Thesis: S.B., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2018.Cataloged from PDF version of thesis.
Includes bibliographical references (page 35).
Grinding and Polishing of small parts is often easily performed by human hands, yet is challenging to automate. The grinding and polishing process is best done using a force-control scheme, which human hands perform naturally. Heavy robotic arms, which favor a position-control scheme, are difficult to control precisely, and trajectory errors can cause excessive grinding force which leads to burning of the part or destruction of the grinding wheel. Prior art of direct force control on a large robot arm requires the end-effector to have a 6-axis dynamometer, which is unwieldy, costly, and greatly limits the speed/precision of the process. We will discuss a new type of grinding spindle which is axially compliant, allowing the position-control robot arm to be used in a force-control nature. The spindle has a disjoint force-displacement curve, effectively operating in two modes: position-control mode at first, until a critical force is exceeded, when the spindle transitions into force-mode, keeping constant grinding force on the part though a certain range of travel. This limits the amount of force which can be imparted during grinding to a safe amount. The spindle is very simple and mechanically robust. We have built this hybrid position-force control spindle and tested it. The spindle was shown to perform correctly and successfully completed the test grind.
by Austin Brown.
S.B.
3
Curtis, David Thomas. "Point grinding and electrolytic point grinding of Udimet 720". Thesis, University of Birmingham, 2011. http://etheses.bham.ac.uk//id/eprint/2850/.
Testo completoAbstract (sommario):
The work within this Thesis is concerned with the manufacturing processes associated with the production of blade root mounting slots in aeroengine compressor and turbine discs. Typically slots are of dovetail or fir-tree geometry dependent on specific design requirements. The state of the art process across the industry is broaching however, despite achieving required geometrical tolerances and surface integrity for decades the process is not without its disadvantages. Primarily these include the inflexibility of the process, machine tool cost; size and cutting forces, complexity of tooling and set up and further the limited level of control of the process beyond tooling design. This has led to research into alternative processes across a range of conventional and non-conventional manufacturing techniques. Work presented here focuses on two key technology areas, namely point grinding and electrolytic point grinding. The former applies small diameter single layer grinding wheels on a high speed machining centre with spindle capability in the region of 60,000rpm. Target geometry was a complex fir-tree root form requiring dimensional control to within +/- 5um and a surface integrity in line with critical aerospace components. The later process investigated the unification of point grinding and electrochemical machining on a vertical machining centre to assess process performance across a range of variables.
4
Liu, Qiang. "Pattern recognition of grinding defects and assessment strategies of grinding". Thesis, University of Nottingham, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.417403.
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5
Gannholm, Sören. "The mysterious grinding grooves". Thesis, Uppsala universitet, Institutionen för arkeologi och antik historia, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-423569.
Testo completoAbstract (sommario):
On the Island of Gotland, there is a phenomenon called grinding grooves, Sw. slipskåror. They occur in bedrock and boulders. About 3600 are known on the island today and having a length of less than half a meter to over one meter. Their purpose was unknown to the scientific community as well as their age. The directions of some 1250 Gotlandic grinding grooves, measured by the author shows there is a correlation to astronomical orientations. An archaeological excavation carried out by the author at a stone with grinding grooves gave some crucial results. The grinding groove phenomenon occurs in some other places in the world as well. In South-West of Sweden, there are quite many in a few places. They are, however shorter and have another appearance because they are more curvature than the Gotlandic ones. Their purpose and age are unknown as well. In France, there are many places with grinding grooves, Fr. polissoirs. Their appearance is more similar to the Gotlandic ones than those in the Swedish mainland. They are supposed to be Neolithic. In Africa and Australia, there are places with different kinds of carvings in stones. Some resemble those mentioned above, more or less. The difference between grinding grooves and other phenomena is floating. They are sometimes associated with the circular indentations called cup marks. There are different explanations, and some are supposed to be marks from creating stone tools, while the cult is the explanation to others.
6
Yin, Guoxu. "Theoretical-Experimental Study of Fluid Delivery and Heat Management in Grinding". University of Toledo / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1438598110.
Testo completo
7
Hekman, Keith Alan. "Precision control in compliant grinding via depth-of-cut manipulation". Diss., Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/16627.
Testo completo
8
Alabed, Asmaa. "Knowledge management for grinding technology". Thesis, University of Huddersfield, 2011. http://eprints.hud.ac.uk/id/eprint/14575/.
Testo completoAbstract (sommario):
This thesis describes an investigation concerned with development of a grinding knowledge warehouse system (GKWS). Based on a study of previous work on knowledge management and technique for a selection of grinding conditions, the thesis proposes a novel methodology to deal with missing data in surface and cylindrical grinding using Genetic Programming. The GKWS provides a guided tool for users to support the decision-making process to provide suggestions for selecting grinding conditions using rule-based reasoning (RBR) and case-based reasoning (CBR) and it can learn from new and previous grinding cases to improve and expand the CBR cases. The GKWS developed a new methodology to deal with missing data in grinding operations. The new methodology is built on If-Then rules, mathematical equations and modelling using genetic programming (GP). Dealing with missing data improves the performance of knowledge discovery in the GKWS and the results of the CBR. The GP is developed for modelling surface roughness in cylindrical and surface grinding. The developed GP model for surface grinding shows the ability to predict the surface roughness parameter especially when the GP terminals vary and the same material and wheel are used. The discussion forum facilitates and supports transferring tacit knowledge into explicit knowledge where the users can exchange their ideas, send questions and answers, and pass on important links. The tacit knowledge is acquired directly from the knowledge engineers. The debate and discussion in GKWS will create new knowledge that is accessible and available when needed.
9
Massam, Mark. "Thermal characteristics of grinding fluids". Thesis, Cranfield University, 2008. http://dspace.lib.cranfield.ac.uk/handle/1826/7615.
Testo completoAbstract (sommario):
High Efficiency Deep Grinding (HEDG) combines high depths of cut, high grinding wheel speeds with high work piece feed rates to deliver a very high stock removal process that can produce components free of surface damage. High contact temperatures are a characteristic of the process and this produces a mass of hot grinding sparks being ejected from the grinding zone. Neat oil cutting fluids are typically used in HEDG due to their excellent lubricity, but the high grinding wheel speeds employed leads to high levels of highly volatile cutting fluid mist in the machine canopy. This mist can mix with the hot grinding sparks being ejected from the grinding zone to create a potential fire hazard. The project aim was to produce a cutting fluid application strategy for the HEDG regime, focusing on establishing the thermal characteristics of cutting fluids in order to determine the optimum cutting fluid for the HEDG process. The cutting fluid application strategy also involved investigating the optimum means by which to apply the cutting fluid, based on minimising amount of cutting fluid used in the process and in reducing the potential fire hazard. The characteristics that have a thermal impact on the grinding process are the cooling, lubrication, ignition and misting properties of the fluid. A series of tests were established to investigate these properties and therefore allow different fluids to be compared and contrasted for their suitability for the HEDG regime based. Once an optimal cutting fluid had been established, the project then investigated the optimal method of applying this fluid, with particular reference to the type and design of the nozzle used to apply the fluid to the grinding zone. As part of these trials, a series of benchmark tests were also conducted using long established cutting fluid application techniques to enable the benefits of the new strategy to be evaluated. The project concluded that high viscosity neat oil ester based cutting fluids were the best fluids to be used in the HEDG regime due to they excellent lubricity and low misting properties coupled to their relatively high resistance to ignition when compared to neat mineral oils. The studies also found that using a high viscosity ester based fluid and then applying it using a coherent jet nozzle, significant reductions in the grinding powder and specific grinding energy could be achieved whilst significantly lowering the amount of mist in the machine, thus reducing the potential fire hazard and the volume of cutting fluid used by the process.
10
Barlow, N. "High-rate grinding wheel design". Thesis, Liverpool John Moores University, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.380664.
Testo completo
11
Li, Yan. "Intelligent selection of grinding conditions". Thesis, Liverpool John Moores University, 1996. http://researchonline.ljmu.ac.uk/5130/.
Testo completo
12
Ebbrell, Stephen. "Process requirements for precision grinding". Thesis, Liverpool John Moores University, 2003. http://researchonline.ljmu.ac.uk/5633/.
Testo completo
13
Oghazi, Pejman. "Traceability in continuous grinding circuits /". Luleå : Division of Mineral Processing, Department of Chemical Engineering and Geosciences, Luleå University of Technology, 2008. http://epubl.ltu.se/1402-1757/2008/34/.
Testo completo
14
Moeller, Gregory V. "Residual stresses due to grinding". Thesis, This resource online, 1995. http://scholar.lib.vt.edu/theses/available/etd-05022009-040807/.
Testo completo
15
Cowan, Richard Watson. "An adaptive statistically based controller for through-feed centerless grinding". Thesis, Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/17570.
Testo completo
16
Shao, Yamin. "Predictive modeling of residual stress in MQL grinding and surface characteristics in grinding of ceramics". Diss., Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/53865.
Testo completoAbstract (sommario):
Surface integrity is of great significance in grinding performance since grinding process is often used as a finishing step. For metallic materials, residual stresses play an important role in surface integrity for its strong effect on fatigue life, corrosion resistance, and part distortion. For ceramic materials, the surface damage induced by grinding process could greatly affect the mechanical strength and surface finish of the component. The functional behavior of machined components can be enhanced or impaired by the grinding process. Because of this, understanding the surface integrity imparted by grinding is very important.
The use of fluid is common in grinding process, however, the high cost and environmental impact of the conventional flood cooling is very undesirable. The minimum quantity lubrication (MQL) have been introduced in industry for about two decades as a promising alternative to conventional flood cooling for economical and environmental advantages. A comprehensive understanding of the MQL effect on the process performances and surface integrity is of great value to the implementation of MQL technique in industrial situation.
Grinding-induced residual stress prediction has been a topic of research since the 1970’s while the studies of MQL grinding is still on the early stage with experimental investigations. A comprehensive study and quantitative description of MQL effect on the residual stress generation in grinding is highly demanded. On the other hand, although there has been significant research in the area of surface damage in ceramic grinding, there are still opportunities for advancing predictive methods. Therefore, the objectives of the current research are set as follows: (1) develop a method of predicting residual stress based on an analytical description of the grinding process under MQL condition, (2) develop a method of predicting surface finish and damage in ceramic grinding, and (3) validate the model with experimental data.
The research will first focus on predicting residual stresses in MQL grinding based on first principles. This includes predictive models of grinding forces, and grinding temperature stemmed from grinding kinematics and dynamics principles as part of the overall modeling effort. The effect of MQL on both lubrication and cooling aspects has been integrated into these models. The mechanical and thermal output parameters will serve as the basis for determining the loading history which generate residual stresses. The research will also aim at surface roughness modeling in ceramic grinding. A ductile-brittle mixed surface generation is predicted based on the nature of ceramic materials and grinding kinematics. The crack system developed from indentation fracture mechanics approach will be utilized in evaluating the brittle mode surface generation. The modeling techniques will be applied to a range of grinding conditions and materials.
This research would aid in evaluating various surface integrities in grinding of metallic and ceramic materials with little experimental efforts. The output could be used to machine these materials effectively to order to improve the functionality of the component.
17
Pena-Diaz, Hernan R. "Experimental validation of an atomization model for fluids used in the grinding process". Thesis, Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/18999.
Testo completo
18
Hänel, Albrecht, Uwe Teicher, Holger Pätzold, Andreas Nestler e Alexander Brosius. "Investigation of a carbon fibrereinforced plastic grinding wheel for high-speed plunge-cut centreless grinding application". Sage, 2018. https://tud.qucosa.de/id/qucosa%3A35379.
Testo completoAbstract (sommario):
High-speed plunge-cut centreless grinding opens up enormous potential for the manufacturing of difficult-to-machine materials and to improve the surface quality while reducing the grinding forces. For this investigation, a new grinding wheel base body of carbon fibre-reinforced plastic (CFRP) was developed to achieve grinding wheel speeds up to 150 m/s in plunge-cut centreless grinding of hardened shafts. For evaluation of the performance characteristics, the grinding forces and the surface quality of different grinding tools were detected. These experiments were conducted using a newly developed measuring system to analyse the grinding forces in the workrest blade. The experimental results are described and discussed in this article.
19
Bell, Andrew John. "Temperatures in high efficiency deep grinding". Thesis, Cranfield University, 2009. http://dspace.lib.cranfield.ac.uk/handle/1826/4422.
Testo completoAbstract (sommario):
This research considers the temperatures generated in the workpiece during profile and cylindrical traverse grinding in the High Efficiency Deep Grinding (HEDG) regime. The HEDG regime takes large depths of cut at high wheel and workpiece speeds to create a highly efficient material removal process. This aggressive processing generates high temperatures in the contact zone between the wheel and workpiece. However, the beneficial contact angle and the rapid removal of the heated wheel – workpiece contact zone results in low temperatures in the finished surface. Temperatures in the ground surface can be predicted with knowledge of the specific grinding energy and the grinding parameters used. Specific grinding energies recorded at high specific material removal rates demonstrated a constant value of specific grinding energy dependent on cutting and contact conditions, improving accuracy of the predictive model. This was combined with a new approach to burn threshold modelling, which demonstrated an improved division of damaged and undamaged surfaces. Cutting and contact conditions in the grinding profile vary dependent on their position. This thesis shows how temperatures vary with location and estimates the partitioning of the heat flux to the regions of the grinding profile. This suggested a constant partitioning of energy to each of the three surfaces considered independently of specific material removal rates. Further a potential link was shown between the surface and the sidewall of the grinding profile, which allows temperatures in a secondary surface to be predicted given knowledge of that in the primary. Finally, the work has demonstrated the feasibility of the Superabrasive Turning process. Using small values of feed per turn and high workpiece feedrates promoted high values of removal rate with low depths of thermal penetration in the as ground surface. Thus the process has become viable for high speed cylindrical traverse grinding.
20
McIvor, Robert E. (Robert Emmett). "Technoeconomic analysis of plant grinding operations". Thesis, McGill University, 1988. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=39209.
Testo completoAbstract (sommario):
This study presents methodology for technical and economic performance analysis of conventional grinding circuits supported by two industrial cases. A review of the strengths and weaknesses of Bond work index and population balance modelling approaches to plant circuit analysis discloses the need to refine work index determinations, and to establish a system of more meaningful ball mill circuit performance parameters.The statistical reliability of carefully determined rod mill work index efficiency ratings is presented. Technical and economic performance improvements through rod mill speed and feed water rate adjustments are presented.
Parameters which separately characterize overall ball mill circuit classification and breakage efficiency are presented. Their relationships with circuit design and operating variables and overall circuit efficiency and economy are discussed. The particle size dependence of flotation is used to estimate the value of the grinding circuit product, and thus to integrate grinding into the overall economics of a flotation concentrator.
21
Conway-Baker, Jamie. "Measurement and modelling of fine grinding". Thesis, University of Exeter, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.403075.
Testo completo
22
Baniszewski, Beth (Beth Ellen). "An environmental impact analysis of grinding". Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/32880.
Testo completoAbstract (sommario):
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2005.Includes bibliographical references (leaves 39-40).
This thesis was intended to investigate the environmental impact of grinding in the United States manufacturing industry. Grinding is an ideal method for producing parts with a fine surface finish and high dimensional accuracy and for shaping hard or brittle workpieces. There are a wide variety of different types of grinding machines, each with different applications and slightly different energy requirements. Workpieces are generally flooded with a stream of coolant while being ground or placed in a spray of coolant mist. Coolant recycling systems are used to filter ground off chips out of coolant and to remove foreign oils and bacteria which pose health hazards. Oil mist collectors both clean mist coolant and prevent the toxic coolant from being inhaled by machinists. In total, 63 *10¹⁵ joules of energy are consumed per year by grinding in manufacturing, 57% of which is directly used in material removal. A total of 1.5*10¹⁰ pounds of scrap chips, spent grinding wheels, and used filters are produced each year as a result of grinding, over 99% of that being scrap chips. About 2.3 million gallons of fluids per year of grinding fluids are incinerated. Grinding creates a significant environmental footprint, creating a need for methods to reduce energy use in grinding and for ways to recycle solid waste that would otherwise be sent to landfills or incinerated.
by Beth Baniszewski.
S.B.
23
Hyde, Paul. "Numerical techniques for optimising rail grinding". Thesis, University of Newcastle upon Tyne, 2012. http://hdl.handle.net/10443/1468.
Testo completoAbstract (sommario):
Grinding of rails is a technique widely used within the railway industry to balance the degradation of the condition of the rail with the required performance of the rail. The principal focus of this research is the impact of wear and rolling contact fatigue (RCF) cracks on structural integrity of rails, and how rail grinding affects this relationship. A numerical model which predicts growth of RCF-initiated cracks in rails has been adapted to take into account periodic grinding of the surface of the rail. The suitability of some of the simplifying assumptions of the adapted model, referred to as the Grinding Model, has been examined with a physical test program, using full scale rail vehicles and track. This test program studied the persistence of the characteristic surface roughness of the rail generated by grinding, and was carried out to determine whether the effect of this roughness on crack growth can be neglected in the Grinding Model. The Grinding Model has been used to predict crack size, in order to investigate the effect of different grinding strategies, consisting of a depth of grinding applied at a certain interval during a representative pattern of rail vehicle traffic over the rail. The use of the Grinding Model to find grinding strategies which match an optimum criterion has been demonstrated. The applicability of this optimisation technique and the model in its current state of development, to the specification of rail grinding operations, in the context of maximising safe rail life and minimising rail life cycle cost, is discussed.
24
Коротун, Микола Миколайович, Николай Николаевич Коротун, Mykola Mykolaiovych Korotun, Я. В. Сорока e Y. V. Soroka. "Measuring and control devices grinding machine". Thesis, Вид-во СумДУ, 2010. http://essuir.sumdu.edu.ua/handle/123456789/5580.
Testo completo
25
Broseghini, Marica. "Modelling of high-energy grinding processes". Doctoral thesis, Università degli studi di Trento, 2017. https://hdl.handle.net/11572/368897.
Testo completoAbstract (sommario):
The comminution and tuning of several structural parameters of materials is often accomplished following a top-down route by high energy grinding. The reduced size of the particles constituting the end product and the incorporation of defects cause modified materials properties and increased solid-state chemical reactivity.
Among grinding devices, the planetary ball mill features high efficiency and versatility, being suitable for almost any kind of material, from metals and ceramics to organic compounds and pharmaceuticals. While its design and the working principle are rather simple, since grinding occurs by impacts between milling media (balls and jar) and mill charge, the characteristics of the end product strongly depend on a multitude of variables, determining balls trajectories and velocities and, in turn, the nature of impulsive forces exchanged during collisions. Numerical models can enourmously contribute to shed light on the process by providing the time evolution of kinematic and dynamic properties of milling media as well as quantities involved in contact events, permitting to understand the role of each milling variable and to design the characteristics of the end product. This Thesis chiefly proposes the implementation of a multibody dynamics model of the planetary ball milling process, its direct and indirect validation – respectively against movie collected in-operando and properties of the end product revealed by the analysis of X-ray powder diffraction data –, the evaluation of the effect of selected milling variables and the investigation of innovative solutions defining specific collisions features, obtained by the re-design of the jar shape. Some relevant case studies are also presented, namely the exfoliation of a bulk for the production of 2D nanostructured materials and the milling of the pharmaceutical compound Efavirenz, aimed at inducing structural and microstructural transformations enhancing dissolution properties.
26
Broseghini, Marica. "Modelling of high-energy grinding processes". Doctoral thesis, University of Trento, 2017. http://eprints-phd.biblio.unitn.it/2749/1/thesis.pdf.
Testo completoAbstract (sommario):
The comminution and tuning of several structural parameters of materials is often accomplished following a top-down route by high energy grinding. The reduced size of the particles constituting the end product and the incorporation of defects cause modified materials properties and increased solid-state chemical reactivity.
Among grinding devices, the planetary ball mill features high efficiency and versatility, being suitable for almost any kind of material, from metals and ceramics to organic compounds and pharmaceuticals. While its design and the working principle are rather simple, since grinding occurs by impacts between milling media (balls and jar) and mill charge, the characteristics of the end product strongly depend on a multitude of variables, determining balls trajectories and velocities and, in turn, the nature of impulsive forces exchanged during collisions. Numerical models can enourmously contribute to shed light on the process by providing the time evolution of kinematic and dynamic properties of milling media as well as quantities involved in contact events, permitting to understand the role of each milling variable and to design the characteristics of the end product. This Thesis chiefly proposes the implementation of a multibody dynamics model of the planetary ball milling process, its direct and indirect validation – respectively against movie collected in-operando and properties of the end product revealed by the analysis of X-ray powder diffraction data –, the evaluation of the effect of selected milling variables and the investigation of innovative solutions defining specific collisions features, obtained by the re-design of the jar shape. Some relevant case studies are also presented, namely the exfoliation of a bulk for the production of 2D nanostructured materials and the milling of the pharmaceutical compound Efavirenz, aimed at inducing structural and microstructural transformations enhancing dissolution properties.
27
Karinkanta, P. (Pasi). "Dry fine grinding of Norway spruce (Picea abies) wood in impact-based fine grinding mills". Doctoral thesis, Oulun yliopisto, 2015. http://urn.fi/urn:isbn:9789526207193.
Testo completoAbstract (sommario):
Abstract Wood powders are used in numerous applications such as thermoplastics and filters, and a lot of research effort has been put into developing novel ways of utilising them. The mechanical processing of wood powders, especially at particle sizes below 100 µm, has been reported in several studies, but they lack information on the effect of fine grinding conditions on the particle morphology and cellulose crystallinity, both of which are important parameters in the further processing of wood powders and in their various applications. This makes it very difficult to design and optimise fine grinding processes with different applications in mind. The aim of this thesis was to study the dry fine grinding of wood in several impact-based fine grinding mills in order to find out their effect on the properties of the wood and to study the energy required for the mechanical processing of the resulting powders. The effect of the main operational parameters on the properties of dried Norway spruce wood and the energy consumption was studied using three impact-based fine grinding mills that were capable of pulverising the wood down to a median particle size of less than 25 µm. It was found that the impact events occurring in media mills can be used for the production of very fine wood powders with lower cellulose crystallinity and rounder shaped particles having more uniform shape distribution than powders pulverised to a similar size range by means of impact events in non-media mills. A practical estimate was obtained for the minimum specific energy consumption in fine grinding in mills involving grinding media that could be utilised as a target for optimisation. Impact-based media milling under cryogenic conditions can be used to obtain different Norway spruce wood powders from those produced under ambient grinding conditions, i.e. without the freezing effect of nitrogen liquid. The energy efficiency of fine grinding can be enhanced by choosing cryogenic rather than ambient conditions. The moisture content of the wood has greater influence on the size and shape of the particles when milling is accomplished under ambient conditions. Torrefaction can reduce the energy consumption in impact-based media mills for median particle sizes over 17.4 µm (± 0.2 µm), while the shape and cellulose crystallinity of the particles are not significantly affected by torrefaction pretreatment as a function of energy consumptionTiivistelmä Puujauheita käytetään laajalti erilaisissa sovelluksissa, kuten esimerkiksi biokomposiiteissa ja suodattimissa. Tämän lisäksi on olemassa paljon tutkimustietoa siitä, kuinka puujauheita voitaisiin hyödyntää laajemminkin. Puu voidaan mekaanisesti prosessoida alle 100 µm:n kokoluokkaan, mutta yksityiskohtaista tietoa kuivahienojauhatuksen olosuhteiden vaikutuksesta jauheiden morfologiaan ja selluloosan kiteisyyteen ei ole saatavilla. Puujauheen morfologialla ja selluloosan kiteisyydellä on kuitenkin merkittävä vaikutus sovelluksia ja jatkojalostusta ajatellen. Puun kuivahienojauhatuksen tiedon puute hankaloittaa merkittävästi prosessin suunnittelua ja optimointia erilaisia sovelluksia varten. Tämän väitöskirjan tavoitteena on selvittää iskuihin perustuvien hienojauhimien vaikutukset puun ominaisuuksiin ja tutkia mekaanisen prosessoinnin energiatehokkuutta hienojauhatuksessa. Tutkimuksessa selvitettiin kolmen erilaisen iskuun perustuvan hienojauhatusmyllyn pääasiallisten operointiparametrien vaikutusta kuivatun metsäkuusen ominaisuuksiin ja energiankulutukseen. Jokaisella hienojauhimella onnistuttiin tuottamaan puujauhoja, joiden mediaanikoko oli alle 25 µm. Iskuihin perustuvalla jauhinkappalemyllyllä saatiin tuotettua puujauhoa, jonka selluloosan kiteisyys on alhaisempi ja partikkelimuodot pyöreämpiä verrattuna samankokoisiin puujauhoihin, jotka on tuotettu iskuihin perustuvilla jauhinkappaleettomilla hienojauhatusmyllyillä. Työssä saatiin käytännöllinen arvio kuivatun metsäkuusen hienojauhatuksen minimienergiankulutukselle iskuihin perustuville jauhinkappalemyllyille, mitä voidaan käyttää kyseisten myllytyyppien optimoinnin tavoitteena. Työssä havaittiin lisäksi, että kryogeenisiä jauhatusolosuhteita käyttämällä voidaan tuottaa erilaisia puujauhoja verrattuna puujauhoihin, jotka prosessoidaan ilman nestetyppijäädytystä, kun jauhatus suoritetaan iskuihin perustuvalla jauhinkappalemyllyllä. Ilman nestetyppijäädytystä puun kosteuspitoisuudella on merkittävämpi vaikutus puujauhojen ominaisuuksiin kuin kryogeenisissä olosuhteissa jauhetuilla. Kryogeenisillä jauhatusolosuhteilla voidaan parantaa myös jauhatuksen energiatehokkuutta. Torrefioinnilla voidaan vähentää hienojauhatuksen energiankulutusta iskuihin perustuvilla jauhinkappalemyllyillä, kun tavoitekoon mediaani on yli 17,4 µm (± 0,2 µm). Torrefioinnilla ei ole vaikutusta selluloosan kiteisyyteen tai partikkeleiden muotoon energiankulutuksen funktiona
28
Yesilay, Yasemin Ayse. "A Computer Simulator For Ball Mill Grinding". Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/2/12605350/index.pdf.
Testo completoAbstract (sommario):
Ball mill grinding is an important operation in the processing of most minerals, in that it may be used to produce particles of the required size and shape, to liberate minerals from each other for concentration purposes, and to increase the powder surface area. Grinding of minerals is probably the most energy consuming task and optimization of this operation has vital importance in processing plant operations to achieve the lowest operating costs. Predicting the complete product size distribution, mill specifications and power draw are important parameters of this optimization.
In this study, a computer simulation program is developed in MATLAB environment to simulate grinding operations using the kinetic model in which comminution is considered as a process continuous in time. This type of model is commonly and successfully used for tumbling grinding mills having strongly varying residence time as a function of feed rate.
The program developed, GRINDSIM, is capable of simulating a ball mill for a specified set of model parameters, estimating grinding kinetic parameters from experimental batch grinding data and calculating continuous open and closed-circuit grinding behavior with mill power input. The user interacts with the program through graphical user interfaces (GUI&rsquos).
29
Onwuka, Goodness Raluchukwu. "Ultra-high precision grinding of BK7 glass". Thesis, Nelson Mandela Metropolitan University, 2016. http://hdl.handle.net/10948/5203.
Testo completoAbstract (sommario):
With the increase in the application of ultra-precision manufactured parts and the absence of much participation of researchers in ultra-high precision grinding of optical glasses which has a high rate of demand in the industries, it becomes imperative to garner a full understanding of the production of these precision optics using the above-listed technology. Single point inclined axes grinding configuration and Box-Behnken experimental design was developed and applied to the ultra-high precision grinding of BK7 glass. A high sampling acoustic emission monitoring system was implemented to monitor the process. The research tends to monitor the ultra-high precision grinding of BK7 glass using acoustic emission which has proven to be an effective sensing technique to monitor grinding processes. Response surface methodology was adopted to analyze the effect of the interaction between the machining parameters: feed, speed, depth of cut and the generated surface roughness. Furthermore, back propagation Artificial Neural Network was also implemented through careful feature extraction and selection process. The proposed models are aimed at creating a database guide to the ultra-high precision grinding of precision optics.
30
Johnstone, Iain. "Critical study of high efficiency deep grinding". Thesis, Cranfield University, 2002. http://dspace.lib.cranfield.ac.uk/handle/1826/3586.
Testo completoAbstract (sommario):
The recent years, the aerospace industry in particular has embraced and actively pursued the development of stronger high performance materials, namely nickel based superalloys and hardwearing steels. This has resulted in a need for a more efficient method of machining, and this need was answered with the advent of High Efficiency Deep Grinding (HEDG). This relatively new process using Cubic Boron Nitride (CBN) electroplated grinding wheels has been investigated through experimental and theoretical means applied to two widely used materials, M50 bearing steel and IN718 nickel based superalloy. It has been shown that this grinding method using a stiff grinding centre such as the Edgetek 5-axis machine is a viable process. Using a number of experimental designs, produced results which were analysed using a variety of methods including visual assessment, sub-surface microscopy and surface analysis using a Scanning Electron Microscope (SEM), residual stress measurement using X-Ray Diffraction (XRD) techniques, Barkhausen Noise Amplitude (BNA) measurements, surface roughness and Vickers micro-hardness appraisal. It has been shown that the fundamentals of the HEDG process have been understood through experimental as well as theoretical means and that through the various thermal models used, grinding temperatures can be predicted to give more control over this dynamic process. The main contributions to knowledge are made up of a number of elements within the grinding environment, the most important being the demonstration of the HEDG effect, explanation of the phenomenon and the ability to model the process. It has also been shown that grinding is a dynamic process and factors such as wheel wear will result in a continuous change in the optimum grinding conditions for a given material and wheel combination. With the significance of these factors recognised, they can be accounted for within an industrial adaptive control scenario with the process engineer confident of a more efficient use of time and materials to produce a higher quality product at lower cost.
31
Farzanegan, Akbar. "Knowledge-based optimization of mineral grinding circuits". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0027/NQ50158.pdf.
Testo completo
32
Hecker, Rogelio Lorenzo. "Power feedback control in cylindrical grinding process". Thesis, Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/16619.
Testo completo
33
Johnson, S. P. "An investigation into below centre centreless grinding". Thesis, Coventry University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234797.
Testo completo
34
Chen, Chien-Hung. "Grinding sludge oil recovery transportation system development". Thesis, University of Canterbury. Mechanical Engineering, 2003. http://hdl.handle.net/10092/6605.
Testo completo
35
Orton, P. A. "Instrumentation and control for precision grinding machines". Thesis, Nottingham Trent University, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.278450.
Testo completoAbstract (sommario):
This thesis examines the present methods of centre less bearing grinding, with a view to applying IIDderncontrol nethods in order to reduce the distribution of output size variations and improve the quality of surface finish. Established rrodels of the grinding process shew that various inportant parameters describing the process can be derived, providing that the grinding power can be accurately rronitored. Several alternative control strategies based on paNer rronitoring are considered. The drive systems of a typical grinding machine are rrodelled as they react through the non-linear grinding wheel/work interface. A simplified computer simulation of the process is demonstrated. Suitable rrethods of instrumentation are evaluated including the optical shaft encoder as a source of high resolution data for the estimation of drive shaft dynamics. A method is devised for on line pararreter estimation of the drive system transfer functions. This enables the important grinding power to be estimated fran shaft dynamics and also al loes the rronitoring of the drive system parameters. The cpt.ica l shaft encoder is also assessed as the source of data for vibration detection. A development conputer with real tine multi-tasking operating system software and specialised shaft encoder interfacing has been established as a basis for an expandable control and rronitoring system. A plan for fee
36
Lacey, S. J. "Condition monitoring of the centreless grinding process". Thesis, Nottingham Trent University, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.355322.
Testo completo
37
Chen, Yinnan. "A generic intelligent control system for grinding". Thesis, Liverpool John Moores University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.388528.
Testo completo
38
Limchimchol, Thitikorn. "Web-based intelligent grinding condition monitoring system". Thesis, University of Nottingham, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.442268.
Testo completo
39
Avril, Nicolas Joseph. "Manufacturing glass-fiber reinforcement for grinding wheels". Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/38432.
Testo completo
40
Brown, Matthew Lasché. "Intelligent robot grinding : planning, optimization, and control". Thesis, Massachusetts Institute of Technology, 1988. http://hdl.handle.net/1721.1/14552.
Testo completo
41
Jing-Kai, Nien, e 粘景凱. "Research of Worm Gear Grinding and Grinding Control". Thesis, 2014. http://ndltd.ncl.edu.tw/handle/sv9z7y.
Testo completoAbstract (sommario):
碩士逢甲大學
自動控制工程學系
102
Abstract The gear grinding process is the finishing process after heat treatment of the gear. At present, the industrial circle mostly use the worm generating gear grinding for mass production of gear grinding process. The worm generating gear grinding machine used by industries in Taiwan was imported from abroad, and the cost of controller is often considered to account for 30% to 50% of the machine. In this article, first we establish the theoretical involute worm mathematical formulas and then describe the spatial relationship between worm and gear by coordinate transformation and derive its trajectory equations, finally we can get the equations of worm and gear by using engaged theory. For the Electronic Gear Box (EGB) controller design, the key technologies include synchronous tracking between the leading axis and the following axis which must be considered first in the worm grinding mechanism and the simultaneous motion control between the leading axes accommodated to the gear-shape construction. In this research, we use Matlab to accomplish the simulation of involute gear-shape and 3D motion simulation of gear grinding.
42
Chen, Hong-Rong, e 陳鴻榮. "The Discussion of Grinding Energy on Grinding Surface Quality". Thesis, 2002. http://ndltd.ncl.edu.tw/handle/03145439991255620352.
Testo completoAbstract (sommario):
碩士國立高雄第一科技大學
機械與自動化工程所
90
Grinding process in one of the common method for precision machining of metals, which is typically applied to the demanded. However, the surface quality of grinding component can’t be realized until it is measured. In order to confirm the tendency and the possible surface characteristic of the grind component, it would seems necessary to monitor the grinding process to instantaneously realize the surface quality. A grinding energy hypothesis for surface quality monitory was proposed in this research. For on-line observation of workpiece quality, two quality were used for the purpose the amount of grinding energy consumed per unit volume ( specific grinding energy ), as well as the speed ratio of wheel surface speed to workpiece feed ratio. A grinding experiment was conducted to conform the relationship theory two quantity and grinding surface quality. The experiment result was analyzed to found out that the grinding surface quality was exponentially proportional to both specific grinding energy and the speed ratio. It was also realized that the higher the specific energy and the speed ratio, a better grind surface well be generated which a larger surface residual stress could be reduced of thus lowering the surface micro-hardness corresponding. A predictive grinding model was also developed in this research work, for the purpose of grinding surface quality prediction.
43
Lin, Chia-Yen, e 林嘉彥. "Three Dimensional Grinding Force Measurement in Mold Grinding Processes". Thesis, 1999. http://ndltd.ncl.edu.tw/handle/79040456950840753604.
Testo completoAbstract (sommario):
碩士淡江大學
機械工程學系
87
In this thesis, a strain gage dynamometer is designed and manufactured to measure three dimensional grinding forces during grinding processes. With a resolution of 0.0096Nt in all 3 directions, this dynamometer is able to measure 2 tangential grinding forces in the range 0.0096 to 200Nt, and the normal grinding force in the range 0.0096 to 250 Nt. The dynamometer is composed of 4 measuring blocks to which strain gages are attached. Measuring blocks are designed so that, upon application of forces, they deform in a way that forces in the x, y, and z directions can be separated with little interaction. These results were confirmed by finite element analyses. The dynamometer is then used to measure grinding forces of the grinding process, the motion which is produced by a hand grinder mounted on the spindle of a NC machine. Results are given for 3 commonly used materials for molds, 3 hand grinder speeds, 3 feed rates for the NC machine, 3 different grinding paths , and 3 diameters of grinding tool. Effects of these factors on grinding forces are investigated. By using the analysis of variance of the Taguchi method, influence of each on all grinding forces (i.e. 2 tangential forces in the x and y direction, the normal force in the z direction, and the resultant force) are obtained. It is found that grinding paths is the most influential factor on all grinding forces. All grinding forces decrease when grinding paths turn along smoother arcs. The second-most influential factor on grinding forces is workpiece material. All grinding forces increase with hardness of materials
44
Huang, Guozhi. "Modelling of sulphide minerals: grinding media electrochemical interaction during grinding". 2005. http://arrow.unisa.edu.au:8081/1959.8/28362.
Testo completoAbstract (sommario):
In this study the unique Magotteaux Mill® system was used to control the grinding chemical conditions, which may be adjusted by varying grinding media, purging gas and pH, during grinding. An electrochemical apparatus was used to investigate oxidation-reduction behaviour of grinding media and sulphide mineral electrodes, as well as their galvanic interaction in-situ of the Magotteaux Mill®. Galvanic interaction between the grinding media (mild steel, 15% chromium, 21% chromium and 30% chromium media) and the sulphide minerals (bornite, arsenopyrite and pyrite) was initially quantified in-situ of the mill by electrochemical techniques under different grinding atmospheres (nitrogen, air and oxygen). An innovative mathematical theoretical model was developed to describe the effect of galvanic interaction on oxidation rates of the grinding media during grinding, which was verified by the experimental data. Galvanic interaction enhanced the oxidation of the grinding media and produced more oxidized iron species in the mill discharge. It was observed that oxidized iron species (EDTA extractable iron) was linear with galvanic current between the grinding media and the sulphide minerals, in agreement with the prediction of the theoretical model. The effect of grinding conditions on pulp chemistry, surface properties and floatability was investigated by the measurement of dissolved oxygen (DO), pH, pulp potential (Eh), ethylene diamine-tetra acetic acid (EDTA) extraction, X-ray photoelectron spectroscopy (XPS) and floatation recovery.PhD Doctorate
45
XIAO, YONG-PING, e 蕭永平. "Studies on Characteristics of surface grinding with conical grinding wheels". Thesis, 1992. http://ndltd.ncl.edu.tw/handle/25600910794839203450.
Testo completo
46
Chen, Alan, e 陳建元. "Grinding Characteristics of Resin CBN Grinding Wheels for SKD11 Steel". Thesis, 2014. http://ndltd.ncl.edu.tw/handle/56785481074219846320.
Testo completoAbstract (sommario):
碩士國立勤益科技大學
機械工程系
102
The purpose of this study is design a new sand stick to decrease compounding recipe times. We all know, Wheel structure of three elements is abrasives, binders and pores. Sand stick and wheel have same structure but different geometric shapes, so this paper manufacturing CBN resin sand stick from wheel process. Previous test wheel surface are often observed by the situation after grinding wheel surface, but this method can’t carefully observe the micro-structural variations in the abrasives and binders after grinding, so this paper design platform can carry out of the sand stick, The platform can put in scanning electron microscope (SEM) cavity, and easy observe the micro-structural variations structure on sand stick worn surface. Actually, CBN resin wheel due to heat generated decrease grinding life and caused poor quality on grinding surface. This study will added (0,1,5 wt%) has better lubricating and thermal effects micron graphite in sand stick, then, grinding hardness of HRC 60 ~ 61 of SKD11 steel. The experimental results showed that: adding 5wt% micron graphite can improve material removed rate, 1wt% micron graphite can obtain better surface quality on workpiece, high grinding ratio, and minimum amount of wear.
47
Chen, Shen-Hang, e 陳聖航. "Studies on the Grinding Mechanism of New Ultra-Precision Ball Grinding Machine". Thesis, 2004. http://ndltd.ncl.edu.tw/handle/38960765473220417585.
Testo completoAbstract (sommario):
碩士國立中山大學
機械與機電工程學系研究所
92
The ceramic ball bearing has been used to exact machine for its good properties such as heat-resistant, corrosion-resisting, and wear-resisting. The old grinding methods of ball bearing spend much time and power. Although the magnetic fluid grinding method economizes time, but cost much money. This study research the effects of spindle speed, grit size, load, and the material of float-ring and fixed-ring on the grinding characteristics by using a new ultra-precision ball grinding machine which developed by our lab. Search the optimum operating conditions of this machine for the requirement of industrial circles. Experimental results show that the converge rate of the saturated value for the sphericity, surface roughness (Ra), and the removal rate are increased with increasing spindle speed, grit size, or load. The sphericity and surface roughness (Ra) are increased when spindle speed, grit size, or load is increased. The sphericity and surface roughness (Ra) are increased with increasing removal rate in using the same grit size and load. Under a certain operating parameter of grinding process, the mean diameter and removal rate are decreased with increasing grinding time. The sphericity and surface roughness (Ra) are better when using the plastic than the float-ring and fixed ring of aluminum, but its removal rate is lower than aluminum’s. First, let the average sphericity achieve saturated value by using diamond grind disk to grinding the Al2O3 ceramic ball. Then, the optimum sphericity can achieve 0.7μm and the surface roughness (Ra) can achieve 0.1μm by using the B4C grits of 0.5μm to grinding.
48
Lin, Tzu-yu, e 林子毓. "Research of Grinding Behavior with CBN Ball Nose AbrasiveCutter by Grinding Fore". Thesis, 2004. http://ndltd.ncl.edu.tw/handle/84251359106874109379.
Testo completoAbstract (sommario):
碩士國立高雄第一科技大學
機械與自動化工程所
92
Abstract Due to high development of the mechanical technology, the needs of the precise components are being increased. Conventionally, most of the precision parts need multiple manufacturing processes; in accordance with the machining of curved surface, the work surface is usually generated using a milling operation to obtain the required geometry. A subsequent finishing operation, such as grinding or polishing, is performed if a better surface is required. Usually, this is done on a different machine tool. Extra set up time and additional non-production time are thus required. This study is to utilize a ball-nose tool coated with CBN abrasive, to fine grind the milled work surface. The process done by the ball-nose tool is intended to be an effective substitute for as-milled finishing operation. In this study, the designed tool was loaded into a machining center as a typically milling cutter. Planning and proceeding the grinding experiment, and observing the change of the grinding force, the condition of the abrasive cutter and the work surface in the grinding process. The results are recorded and analyzed in the grinding process, in accordance with investigation of grinding behavior. After computing the grinding force of the experimental results, the variation of the grinding force was obtained describe the grind behavior. After proper analysis, the variation of the grinding force was found to be directly proportional to the grain abrasion. Besides, wheel grain abrasion was found to be affected the surface roughness of the abrasive cutter. When surface roughness becomes too smooth, would indicate an apparent abrasion of the wheel surface. The lower the spindle speed and the higher the feed rate, the abrasion of the grain would easily become more remarkable. The result of this research, provide an observation of the grinding behavior of the CBN-abrasive in the process, which thus give good reference for subsequent use.
49
Horng, Yeh Jenq, e 葉政宏. "Studies on the Grinding Characteristics of New Ultra-Precision Ball Grinding Machine". Thesis, 1999. http://ndltd.ncl.edu.tw/handle/67419070273340804680.
Testo completoAbstract (sommario):
碩士國立中山大學
機械工程學系
87
This study develops kinematic analysis of ball grinding process, to realize the skidding mechanism. The effects of grit size, load, and spindle speed on the grinding characteristics is investigated by using a new ultra-precision ball grinding machine to search the optimum operating conditions of this machine. For the Al2O3 ceramic ball made in Taiwan, experimental results show that the converge rate to a saturated value for the sphericity and the removal rate increase with increasing grit size, load, or spindle speed. The sphericity increases when grit size or spindle speed increase, but is doesn’t depend on load. The surface roughness increases with increasing grit size, but it is independent of load or spindle speed. The sphericity increases with increasing removal rate using the same grit size and load. Under a certain operating parameter, the mean diameter decreases with increasing grinding time, but surface roughness and removal rate don’t change with increasing grinding time. Experimental results show that the best sphericity can achieve 1.5 μm. For Al2O3 ceramic ball made in Japan, the grinding characteristics are the same as Al2O3 ceramic ball made in Taiwan in qualitative analysis. However, the higher removal rate, the higher sphericity, and the higher surface roughness can be qualitatively obtained for Japanese ceramic’s ball by using the present machine.
50
Tang, Ming. "Computer Aided Manufacturing for gear grinding process using Constant Grinding Force method". 1986. http://catalog.hathitrust.org/api/volumes/oclc/15493841.html.
Testo completoAbstract (sommario):
Thesis (M.S.)--University of Wisconsin--Madison, 1986.Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 142-143).