Dissertations / Theses on the topic 'The cutting of flat shapes'

This thesis deals with the cutting of flat shapes of polystyrene by industrial robot using Robotmaster. There are some variants of the shaped components that can create by using Robotmaster. The task of the work is also a demonstration task in the realization of use a resistance wire as a tool and polystyrene boards as a workpiece material.

Thesis (Ph. D.)--Ohio State University, 2005.
Title from first page of PDF file. Document formatted into pages; contains xxi, 261 p.; also includes graphics (some col.). Includes bibliographical references (p. 244-254). Available online via OhioLINK's ETD Center

This study documents the deformation history of the Santa Rita Flat pluton, eastern California, from the time of emplacement to post-emplacement transpressional shearing, and consists of manuscripts that make up three chapters. The first chapter addresses the emplacement of the Santa Rita Flat pluton using anisotropy of magnetic susceptibility (AMS). The second chapter describes the kinematic analysis of cross-cutting shear zones within the western margin of the pluton. The third chapter is an informal paper on the U/Pb dating of two sheared felsic dikes from the pluton. AMS of the Santa Rita Flat pluton indicates that the paramagnetic and ferromagnetic minerals define a foliation which is arched into an antiformal structure in the central to southern parts of the pluton. The northern part of the pluton displays an east-west striking magnetic foliation which lacks a fold-like geometry. Previously published field mapping and petrologic surveys of the pluton and surrounding wall rocks indicate that the southern margin and northern part of the Santa Rita Flat pluton represents the roof and core of the pluton, respectively. Integration of our analysis of the internal structure of the pluton with previously published work on the regional structure of the surrounding metasedimentary wall rocks, suggests that the pluton may have initially been intruded as a sill-like or "saddle reef" structure along a stratigraphically controlled mechanical discontinuity in the hinge zone of an enveloping regional-scale synform. Subsequent vertical inflation of this sill resulted in local upward doming of the overlying pluton roof and formation of the antiformal structure now observed at the current erosion level in the central-southern part of the pluton and overlying locally preserved roof rocks. No corresponding fold structure is indicated by AMS analysis in the northern part of the pluton, which is exposed at a deeper level, and represents a section closer to the pluton core. Emplacement of the Santa Rita Flat pluton at 164 Ma overlaps in time with regional deformation at ~185 - ~148 Ma (Middle - Late Jurassic) recognized in the southern Inyo Mountains. Northwest trending folds are pervasive along the western flank of the Inyo and White Mountains, and may have accommodated strains at the lateral tips of thrust faults which crop out in the southern Inyo Mountains. We speculate that space for initial emplacement of the Santa Rita Flat pluton may have been produced by layer-parallel slip and hinge-zone dilation, accompanied by axis-parallel slip during formation of a regional scale thrust-related synform. The Santa Rita shear system (SRSS) is composed of a series of discrete NW-SE striking steeply dipping shear zones that cut and plastically deform granitic rocks of the Santa Rita Flat pluton. The shear zones exhibit a domainal distribution of gently and steeply plunging stretching lineations, and are located at planar mechanical discontinuities between the granite and a series of felsic/mafic dikes which intrude the pluton. Mylonitized dikes within the shear zones contain syntectonic mineral assemblages not observed in dikes outside the shear zones, indicating that the dikes were intruded prior to shear zone development. Correlation with geometrically similar shear zones in the Sierra Nevada batholith to the west, suggests that the SRSS probably nucleated from a regional stress field in Cretaceous times (~90-78 Ma). Strain is heterogeneous within the shear zones, with local development of protomylonite, mylonite, ultramylonite and phyllonite. Strain heterogeneity within the granite is attributed to fluid infiltration and chemical reaction and alteration of feldspar to fine-grained mica. These deformation-induced mineral changes would have resulted in progressive mechanical weakening over time of rocks within the SRSS. The phyllonites occur predominantly within steeply lineated shear zones and contain mylonitized foliation-parallel quartz veins. The pattern of c-axis preferred orientation in these quartz veins indicates that deformation within the shear zones occurred under plane strain conditions. Locally, quartz veins also cut the foliation planes, reflecting high pore fluid pressures during evolution of the SRSS. These cross-cutting quartz veins are also plastically deformed, and their c-axis patterns indicate weak constrictional strains. The orientation of the shear zones, together with their strain paths, are used to develop a transpressional kinematic model for development of the SRSS within a progressively rotating stress field.
Master of Science

The laboratory cutting specific energy is widely used to estimate the cuttability of rocks by a roadheader fitted with sharp picks. Sharp picks on the other hand become blunt due to wear in time and require replacement. Although it is known that the pick blunting affects adversely the rock cuttability, no study exists to show the relationships between the degree of pick wear and the cutting specific energy obtained by standard cutting tests. In this study, standard cutting tests were carried out on different rock types, with picks having varying degrees of blunting. The relationships between wear flats and the cutting forces, specific energies and size distribution for various rock properties such as uniaxial compressive strength, tensile strength, cone indenter number, shore hardness, schmidth hammer hardness, density and grain size were established. The mean cutting force and the cutting specific energy have been found to increase 2-3 times and 4-5 times respectively with 4 mm wear flat as compared to sharp picks as the strength and density of rocks increase. No relation exists between mineral grain size and the cutting performance. A definite relation could not be established between the wear land and the size distribution of the product. Charts have been produced to predict critical wear flats for different rock property values considering 25 MJ/m³
as the limiting specific energy above which poor cutting performance occurs. Nine prediction models have been developed by statistical analysis to estimate the laboratory cutting specific energy from various rock properties and wear rates.

No estado do Rio Grande do Sul, estão localizadas importantes regiões de extração e processamento do material gemológico ágata. No Distrito Mineiro do Salto do Jacuí encontram-se as maiores jazidas de ágata do Brasil e do Mundo. No município de Soledade se concentram as principais empresas de beneficiamento e comércio de materiais gemológicos. Apesar da abundância de material, a maioria dos objetos produzidos apresenta baixo grau de inovação, os produtos oferecidos no mercado são muito semelhantes entre si e tem, em comum, a falta de diferencial e de utilização de processos que envolvam tecnologia. A ágata é geralmente exportada em estado bruto ou apresentando baixo grau de aproveitamento. O processamento mais comum, utilizado na maior parte das empresas, é o corte em chapas que posteriormente são lixadas, polidas e tingidas em diversas cores. Entre as empresas pesquisadas no presente estudo apenas uma já utiliza processos envolvendo novas tecnologias. Pode-se afirmar que a pesquisa e estudos que auxiliem em um melhor aproveitamento do material ágata possam representar novas oportunidades de produção de objetos e adornos pessoais (jóias) modificando um cenário onde o design inovador é pouco explorado e apresentado. A metodologia empregada para a realização deste estudo contemplou etapas de conhecimento da realidade dos locais de extração, beneficiamento e comercialização de ágata, avaliação dos processos, ensaio de usinagem convencional CNC, ensaios de usinagem não convencional por jato d’água CNC e desenvolvimento de produtos em formas complexas. Foram realizados vinte e quatro ensaios de usinagem, a análise posterior identifica larguras e espessuras ideais buscando a otimização da matéria-prima. Desta forma foi possível alcançar o objetivo principal nesta pesquisa de realizar o corte de ágata com utilização de tecnologia CNC em peças com formas complexas.
Rio Grande do Sul State, Brazil, has important regions of extraction and processing of agate. Salto Jacuí Mining District, in the central region of this State, is one of the largest and more importante agate’s mines region of Brazil and even of the World. In Soledade town, there are the most important gemstone processing and trade companies of this State. Despite the abundance of gem materials, most of the objects produced in the different companies are very similar and have in common that they seldom are manufactured using new technological processes. Agate is usually exported as raw material or as cut polished slabs which can be dyed in various colors. Among several companies studied in this research, only one uses industrial processes involving new technologies. So, scientifical studies to indicate a better use of agate produced in Rio Grande do Sul, can provide new opportunities for the production of objects and personal ornaments (jewelry), modifying the trade where innovative designs are little explored. The methodology used in this study had several steps: identification of the extraction, processing and trade places of agate; evaluation of the industrial benefit processes used in agate; testing of conventional CNC machining on agate slabs; and testing on agate slabs of non-conventional computer controled machining by water jet cutting (WJC), with development of complex forms agate products. Twenty-four machining tests were carried out, with further analysis identifying ideal widths and thicknesses to optimize the use of agate raw material. With these tests, it was possible to achieve the goal of this study, which is to cut agate using water jet technology, in order to produce agate objects with complex forms.

碩士
南開科技大學
車輛與機電產業研究所
98
In this paper, the finite element method is used to investigate the effect of punch shapes (oblique, convex and concave) on press cutting of a square pipe. A series of simulations on the press cutting using the FEM program DEFORM 3D was carried out. The influence of punch shapes on the pipe cutting history, the punch load and the effective stress of punch tool was examined. Experiments were carried out with low steel square tube at room temperature, and the results of experiments were compared with the FEM calculations. It is found that the punch load has minimum value by using the oblique punch, whereas the maximum effective stress of punch tool has minimum value by using the convex punch.

碩士
大葉大學
工業工程研究所
88
Packing and cutting problems arise in many industries such as clothing, furniture, steel, shipbuilding, and footwear. Hence any savings in the utilization rate of material used can result in a big reduction in the production cost. Lots of research in the literature is, thus, devoted in finding the optimal way of cutting or packing patterns in the given plates. Since it is almost impossible to find the real optimum for the packing/cutting problems, developing heuristic approach for the problems is therefore more appropriate than exact methods. In this study, we propose a simulated annealing (SA) approach for packing patterns with irregular shapes. Extensive efforts have been spent in finding the best clustering policy among parts. Several parameters controlling the mechanism of SA are also validated through some experiments to accelerate the convergence of the SA algorithm. An empirical data from a footwear company in Taiwan is adopted to test the effectiveness of the proposed algorithm.

博士
國立高雄應用科技大學
機械與精密工程研究所
103
Milling is not only the most common processes in machining, but also is very popularly employed in computer numerical control (CNC) machines for metal material removal operations. Reliable quantitative prediction of cutting force coefficients and cutting forces in milling is very important to predict machining characteristics such as the power and torque requirements, machine tool vibrations, surface quality, geometrical accuracy, and stability, and so on, and to develop the machining processes. In this dissertation, a linear model of average cutting force and feed per flute was developed in which the cutter’s helix angle is incorporated to calculate the cutting force coefficients for the milling process. By the developed mathematical model, with the appropriate stable cutting conditions, the cutting force coefficient model was formulated by a function of average cutting force and cutter geometry such as cutter diameter, number of flutes, cutter’s helix angle. The speciality, different to some previous studies, of the proposed formulation to calculate the cutting force coefficients in flat-end milling were built with the effect of cutter’s helix angle. On the effect of cutter’s helix angle, all derivations of cutting forces are directly based on the tangential, radial, and axial cutting force components. The cutter’s helix angle played a significant factor for determination of cutting force coefficients. So, when building the model to calculate the cutting force coefficients, the cutter’s helix angle should be considered. This cutting force coefficient model was applied for several pairs of tool and workpiece at the appropriate stable cutting conditions with several cutting types. The linear model of average cutting force and feed per flute was successfully verified experimentally with very promising results. By performing the milling tests at the appropriate stable cutting conditions, all six cutting force coefficients were determined from experimental data. The optimum values of cutting force coefficients were evaluated and selected through the comparisons of predicted and measured forces. An experimental method to determine the stable cutting condition was proposed. By this method, the chatter could be prevented, and the effect of vibration and other factors related to the accuracy in calculating cutting force coefficients was reduced in the milling process. This method can be applied for other machine-tool-workpiece systems in investigation of cutting force coefficients in milling processes. The dynamic structure of machine tool was determined by using CUTPROTM software through experiments. The obtained dynamic structure data were used to develop the force model in calculating dynamic cutting force. The predicted results from developed model agree satisfactorily with experimental results. The developed model was then successfully applied to predict the cutting forces and other machining characteristics such as machine tool vibration, spindle power, spindle torque, tool deflection, and so on. Besides, the integrated application with a virtual three-axis milling machining simulation system has also been implemented to demonstrate potential utilization of this research showing very promising potential. The investigated results can be applied in the usages of machine tool in industrial manufacturing.

碩士
國立屏東科技大學
車輛工程系所
101
The purpose of this thesis is to build up an automatic machinery on glass cutting for arbitrary shapes using Nd:YAG laser. The process contours can be organized by interpolation method, which is leading to achieve a process platform with high performance and accuracy. The study includes four parts: the platform mechanism design, the control circuit design, platform verification, and testing for arbitrary shape cutting. First, the machine platform will mainly refer to CNC machine platform design and then be modified to a new three-dimensional moving column machining platform. Furthermore, the process platform was driven with stepper motors on the control circuit system, and an "Arduino" motion axis card was used to control a three-axis movement of process platform. Hence, the entire process platform has various functions, such as origin reset, interpolation calculation, accelerate and deceleration control of motor, manual joystick control and laser on/off control. Moreover, the accuracy of entire automatic machinery can be proved to reach to 0.01mm by using laser displacement meter, and that will conform the accuracy requirements for process platform. Finally, the experimental results showed that even at low laser power, the laser glass cutting will be still implemented by decreasing laser moving speed due to the effectively accumulation of laser energy. Summary, this automatic machinery based on computer program compilation will make "Arduino" control card effectively transfer the pulse signal to driving motors by interpolation method. Thus the process platform can move in a micro-steps way to achieve the expected process contours and the goal of arbitrary glass cutting.

Planning of optimal toolpath, cutter orientation, and feed rate for 5-axis Computer Numerical Control (CNC) machining of curved surfaces using a flat-end mill is a challenging task, although the approach has a great potential for much improved machining efficiency and surface quality of the finished part. This research combines and introduces several key enabling techniques for curved surface machining using 5-axis milling and a flat end cutter to achieve maximum machining efficiency and best surface quality, and to overcome some of the key drawbacks of 5-axis milling machine and flat end cutter use. First, this work proposes an optimal toolpath generation method by machining the curved surface patch-by-patch, considering surface normal variations using a fuzzy clustering technique. This method allows faster CNC machining with reduced slow angular motion of tool rotational axes and reduces sharp cutter orientation changes. The optimal number of surface patches or surface point clusters is determined by minimizing the two rotation motions and simplifying the toolpaths. Secondly, an optimal tool orientation generation method based on the combination of the surface normal method for convex curved surfaces and Euler-Meusnier Sphere (EMS) method for concave curved surfaces without surface gouge in machining has been introduced to achieve the maximum machining efficiency and surface quality. The surface normal based cutter orientation planning method is used to obtain the closest curvature match and longest cutting edge; and the EMS method is applied to obtain the closest curvature match and to avoid local gouging by matching the largest cutter Euler-Meusnier sphere with the smallest Euler-Meusnier sphere of the machined surface at each cutter contact (CC) point. For surfaces with saddle shapes, selection of one of these two tool orientation determination methods is based on the direction of the CNC toolpath relative to the change of surface curvature. A Non-uniform rational basis spline (NURBS) surface with concave, convex, and saddle features is used to demonstrate these newly introduced methods. Thirdly, the tool based and the Tri-dexel workpiece based methods of chip volume and cutting force predictions for flat-end mills in 5-axis CNC machining have been explored for feed rate optimization to achieve the maximum material removal rate. A new approach called local parallel slice method which extends the Alpha Shape method - only for chip geometry and removal volume prediction has been introduced to predict instant cutting forces for dynamic feed rate optimization. The Tri-dexel workpiece model is created to get undeformed chip geometry, chip volume, and cutting forces by determining the intersections of the tool envelope and continuously updating the workpiece during machining. The comparison of these two approaches is made and several machining experiments are conducted to verify the simulation results. At last, the chip ploughing effects that become a more serious problem in micro-machining due to chip thickness not always being larger than the tool edge radius are also considered. It is a challenging task to avoid ploughing effects in micro-milling. A new model of 3D chip geometry is thus developed to calculate chip thickness and ploughing volume in micro 5-axis flat-end milling by considering the minimum chip thickness effects. The research forms the foundation of optimal toolpath, cutter orientation, cutting forces/volume calculations, and ploughing effects in 5-axis CNC machining of curved surfaces using a flat-end mill for further research and direct manufacturing applications.
Graduate
0548
luoshan@uvic.ca