The development of unmanned machining systems has been a recent focus of manufacturing research. Computer Numerical Control (CNC) units, which monitor and control many tightly coupled machining tasks, are inseparable parts of the unmanned manufacturing system. This thesis addresses the detailed design and analysis of a modular CNC system for a milling machine. The feed drive control system of the machine tool is thoroughly studied. The mathematical model for the feed drive control system, which consists of a motion controller, power amplifiers and DC-servo motors, is developed and experimentally verified. A method of estimating cutting forces from current drawn by feed drive motors is developed. The viability of the current sensor as a feeding-force sensing component is illustrated and experimentally tested on the milling machine. Successful application of the current sensor to tool breakage detection in milling operation is presented. The performance of the multi-axis contouring system in precision machining is discussed. The contouring errors induced by feed drive positioning systems in CNC machine tools is investigated using the state space model of the CNC system. The influence of the cutting force on the accuracy of machining is shown to be negligible for feed drives driven by ball leadscrews. Various control strategies for the improvement of machining accuracy are tested in the simulation studies. / Applied Science, Faculty of / Mechanical Engineering, Department of / Graduate

A software package and associated hardware have been developed which gives users of the ORAC CNC Training Lathe an easier and faster method of manufacturing on the lathe. The package, entitled ORACAP, uses the computing power of a mini-mainframe computer, a VAX 11/750, to assist in part design, program generation, program optimization, and program proving for the ORAC Lathe. The package is designed for users unfamiliar with computers such as students in an educational institute or workers in a production facility and uses command procedures to simplify the preparation and execution of the modules of the package. In addition to providing users with a valuable tool for manufacturing, ORACAP also gives users insight into the Computer Aided Design and Computer Aided Manufacturing methods used in industry, that is, it demonstrates the methods which allow production of a part from a very concise description of its geometry. Finally, ORACAP demonstrates the production advantages of a CAD/CAM system over conventional manufacturing methods for small to medium size batch production. / Applied Science, Faculty of / Mechanical Engineering, Department of / Graduate

The purpose of this study is threefold. First, numerical control will be analyzed objectively to ascertain its justification in terms of meeting the requirements of the basic manufacturing process phases. Secondly, the study will consist of an evaluation of the field of industrial arts in the Dallas-Fort Worth area to determine how numerical control has been accepted in the educational field and what preparation, if any, is being made to include the teaching of this new industrial concept. Thirdly, the study will investigate the feasibility and cost of installing numerically controlled equipment in the industrial arts laboratories of North Texas State University.

Call number: LD2668 .T4 1964 L735 / Master of Science

Typescript (photocopy). / Digitized by Kansas Correctional Industries

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Electrical Discharge Machining (EDM) is a non-contact manufacturing process in which material is removed from a metal workpiece by high frequency electrical pulses produced between an electrode and the workpiece. EDM machines are usually stand-alone devices, and are quite expensive. The objective of this research was to integrate an EDM machine and an existing reconfigurable CNC machine tool, using a modular approach, to enable conventional milling and EDM to be conducted in a co-ordinated fashion on the same machine tool.

During the past three years, a research project has been carried out in the Department of Mechanical Engineering at UCT, directed at developing a system to accurately reproduce three-dimensional (3D), sculptured surfaces on a three axis computer numerically controlled (CNC) milling machine. Sculptured surfaces are surfaces that cannot easily be represented mathematically. The project was divided into two parts: the development of an automatic noncontact 3D measuring system, and the development of a milling system capable of machining 30 sculptured surfaces (Back, 1988). The immediate need for such a system exists for the manufacture of medical prostheses. The writer undertook to investigate the measurement system, .with the objective to develop a non-contact measuring system that can be used to 'map' a sculptured surface so that it can be represented by a set of XYZ coordinates in the form required by the milling system developed by Back (1988). This thesis describes the development of a PC-based near-realtime photogrammetry system (PHOENICS) for surf ace capture. The topic is introduced by describing photogrammetric principles as used for non-contact measurements of objects. A number of different algorithms for image target detection, centering and matching is investigated. The approach to image matching adopted was the projection of a regular grid onto the surface with subsequent matching of conjugate grid intersections. A general algorithm which automatically detects crosses on a line and finds their accurate centres was developed. This algorithm was then extended from finding the crosses on a line, to finding all the intersection points of a grid. The algorithms were programmed in TRUE BASIC and specifically adapted for use with PHOENICS as an object point matching tool. The non-contact surface measuring technique which was developed was used in conjunction with the milling system developed by Back (1988) to replicate a test object. This test proved that the combined system is suitable for the manufacture of sculptured surf aces. The accuracy requirements for the manufacture of medical prostheses can be achieved with the combined measuring and milling system. At an object-to-camera distance of 0.5 m, points on a surface can be measured with an accuracy of approximately 0.3 mm at an interval of 5 mm. This corresponds to a relative accuracy of 1:1600. Back (1988) reported an average undercutting error of 0.46 mm for the milling system. This combines to an uncertainty of 0.55 mm. Finally, the limitations of PHOENICS at its prototype stage as a surface measuring tool are discussed, in particular the factors influencing the system's accuracy. PHOENICS is an ongoing project and the thesis is concluded by some recommendations for further research work.

<p> This thesis is a feasibility study of the application of a point-to-point numerical control (N/C) machine for contour cutting work. It comprises three basic parts which are divided into ten chapters. </p> <p> The first part deals with the primary objectives of this project and the N/C machine's hardware and software descriptions. </p> <p> The second part introduces the utilization of computer-aided programming and presents an original translation program necessary for this particular work. </p> <p> The last part gives several examples and describes the outcomes of the study; and is concluded with some objective discussions. </p> / Thesis / Master of Engineering (MEngr)