Thesis (M.S.)--University of Wisconsin--Madison, 1964. / eContent provider-neutral record in process. Description based on print version record. Bibliography: l. 82-84.

Thesis (Ph.D.) -- McMaster University, 2001. / Includes bibliographical references (leaves 251-260). Also available via World Wide Web.

Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2006. / Includes bibliographical references (leaves 83-89). Also available in electronic version.

Prototyping is an essential step in the manufacture of many objects, both consumer and industrial. A fundamental step in this process is the definition of the three dimensional form of the object shape; for example, a designer's models created in clay or wood. A three dimensional vision system (range sensor) offers the advantage of speed in defining shapes compared to traditional tactile sensing. In this thesis, the viability of using range sensors is demonstrated by developing a rapid prototyping system comprised of a laser-based range sensor and software that creates a computer model of the object. One particularly important application of the computer model is for the generation of a control program, or toolpath, for a computer-numerically-controlled (CNC) machine tool. This is an important application in mold and die manufacture and mold manufacture for automobile components from full scale models. The computer model can also be incorporated into computer aided design and analysis programs. The most suitable vision system, for rapid prototyping applications, has been selected from a group of available sensors and integrated with a coordinate measuring machine that acts as a translation system. The range data produced have been utilised in a multi-patch surface modelling approach in order to model objects where many types of surface patches, such as quadric and free form, are blended together on one object. This technique has been demonstrated to provide accurate and smooth surface reconstructions that are suitable for generating CNC toolpaths. The viability of machining from multiple surface patch models has been demonstrated and, in addition, a new technique for the machining of free form surfaces developed. An alternative method for fully defining complex three dimensional shapes employing a rotary sensing of the object is also presented that permits the efficient generation of CNC machine toolpaths. / Graduate

No description available.

No description available.

This study investigates the use of vibration and strain measurements on machine tools in order to identify the propagating wear of the selected tools. Two case studies are considered, one of which was conducted in the plant of a South African piston manufacturer. The purpose of the ftrst case study was to investigate the feasibility of vibration monitoring to identify tool wear, before attempting to implement a monitoring system in the manufacturing plant. During this case study, data from a turning process was recorded using two accelerometers coupled to a PL202 real time FFT analyser. Features indicative of tool wear were extracted from the sensor signals, and then used as inputs to a Self-Organising Map (SOM). The SOM is a type of neural network based on unsupervised learning, and can be used to classify the input data into regions corresponding to new and worn tools. It was also shown that the SOM can also be used very efficiently with discrete variables. One of the main contributions of the second case study was the fact that a unique type of tool was investigated, namely a synthetic diamond tool specifically used for the manufacturing of aluminium pistons. Data from the manufacturing of pistons was recorded with two piezoelectric strain sensors and a single accelerometer, all coupled to a DSPT Siglab analyser. A large number of features indicative of tool wear were automatically extracted from different parts of the original signals. These included features from time and frequency domain data, time series model coefficients as features and features extracted from wavelet packet analysis. A correlation coefficient approach was used to auto-lJUltically select the best features indicative of the progressive wear of the diamond tools. The SOM was once again used to identify the tool state. Some of the advantages of using different map sizes on the SOM were also demonstrated. A near 100% correct classification of the tool wear data was obtained by training the SOM with two independent data sets, and testing it with a third independent data set. It was also shown that the monitoring strategy proposed in the second case study can be fully automated and can be implemented on-line if the manufacturer wishes to. Some of the contributions of this study are the use of the SOM for tool wear classification, and conclusions regarding the wear modes of the synthetic diamond tools. / Dissertation (M Eng (Mechanical Engineering))--University of Pretoria, 2006. / Mechanical and Aeronautical Engineering / unrestricted

Call number: LD2668 .T4 1963 M49 / Master of Science

published_or_final_version / Mechanical Engineering / Doctoral / Doctor of Philosophy

Thesis (Ph.D.)--McMaster University, 2005. / Supervisors: M.A. Elbestawi, G.M. Bone. Includes bibliographical references (leaves 117-122).