Mechanical Engineering - Theses
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ItemAssembly line sequencing for product-mix( 1971)This thesis is concerned with the sequencing of various models of a product when these are manufactured on one assembly line using product-mix. A simplified model of the assembly line is postulated. Four heuristic algorithms are developed which aim at minimizing assembly line length while avoiding operator interference. Two of these algorithms are used in a factorial experiment to determine the relationship between assembly line length and five factors. These factors are characteristics of the production requirement and workload balance. From the experimental results, empirical equations are developed which are a useful aid in the design of new assembly lines or the balancing of existing assembly lines. The experimental results are also analyzed to determine a range of sequencing problems for which near optimal sequences can be expected using the two algorithms.
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ItemCreative design skills of engineering students( 1972)An investigation has been carried out into the creative design skills of engineering students in the University of Melbourne. In order to tap students' creative abilities, open-ended design problems representative of those encountered by the professional engineer in practice were devised. Students' responses to the problems were then observed and analyzed. The results showed that there were many interesting and apparently important aspects of the students' creative problem-solving behaviour which could be identified and measured, but which were not revealed by performance in conventional university examinations. These aspects of problem-solving appear to be important from the point of view of the students' later professional careers, but further work is needed to confirm this.
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ItemA study of the drilling process( 1970)The modern two flute twist drill has been in existence for more than fifty years and the drilling process has become one of the most widely used manufacturing operation. There has hardly been any major alteration in the general appearance of the twist drill despite the various studies on the effect of geometry on drill performance such as tool life and cutting forces. Nevertheless a better understanding of the capabilities and limitations of the twist drill has been made possible by these investigations. The twist drill generates holes by the cutting action of the lips and the indenting action of the chisel edge. The geometry of the lips has been generalized to that of a lathe tool and the cutting action of the lips was reported as similar to single edged oblique cutting. A cutting model for drilling has not been developed possibly because of the complex geometry of the lips and the extruding action of the chisel edge, which is difficult to study. As a result many empirical equations for the prediction of forces have been proposed. In this project the geometry of the various size drills will be studied. Analyses of the mechanics of drilling will be attempted in the hope that a cutting model may be constructed based on established principles of orthogonal and oblique cutting. This is desirable since in the design and application of drilling, like in other topics of metal cutting) it is useful to be able to predict the deformation and cutting forces.
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ItemEffect of tool form and workpiece geometry in metal cutting( 1970)A survey on the mechanics of cutting has been carried out. It is shown that little or no work has been done on the cutting analyses of practical three dimensional machining operations such as form cutting or turning. (Appendix A). Thin shear plane deformation analyses are developed for double edged tools. These involve triangular tools performing full depth and chevron type vee grooves as well as lathe cuts. Two alternative yet similar analyses are derived for lathe cuts. A numerical investigation of these analyses is made from which it is shown that the dimensionless power force FP/TA is related to the chip length ratio and is virtually independent of all other variables. Thus variables which alter the chip length ratio will change the forces in machining. These analyses, like all other orthogonal cutting analyses, cannot theoretically predict the chip length ratio although it can be experimentally measured with relative ease and rudimentary equipment. It is also found that there is no theoretical justification for the chip flow rule nc = i in turning. The geometry and specification of lathe tools is studied and the problems and errors in grinding such tools are determined. The difficulty of finding the ‘best’ specification with respect to the theory of cutting is considered by applying the single edge oblique cutting theory and the developed double edged tool analyses. It is shown that no positive conclusion can be achieved without theoretical predictions of the chip length ratio. An experimental investigation is carried out to check the analyses. A series of orthogonal cutting tests is run to form a basis for comparisons with the other cutting operations. Statistical methods such as regression analysis, analyses of variance and co-variance are used to process the data. It is found that the experimental trends for the various tool-work combinations are consistent with those obtained from orthogonal cutting. The measured forces in cutting are shown to be due to cutting-edge forces and deformation forces represented by the analyses of cutting. The shear stress in orthogonal cutting is constant and compares favourably with the constant values found from full depth triangular cuts as well as from higher speed up-milling results. Substantial qualitative and quantitative correlation is achieved between all the tests run showing that the analyses are reasonable representations of the physical case. Methods of using the analyses for predicting the forces in machining are developed and discussed.