The object of this study was to apply the technique of synthesis to the design of a small power saw. The study produced experimental data on optimum chain speeds, engine vibrations, noise levels, and heat transfer coefficients for reciprocating cylinder heads, and led to a simple free-piston configuration in which a piston oscillated between a mixture of air and fuel in one end of a closed cylinder and a spring in the other. The feasibility of developing the configuration into a practical reciprocating engine was verified by designing, building and testing a prototype. The prototype incorporated such novel features as instant, effortless starting and stopping, automatic throttling, self-cooling, compression ignition of a carbureted air-fuel mixture, and a balanced engine. Uncontrolled ignition timing reduced engine efficiency, and the lack of inertia made engine stalling easy and carburetor adjustment difficult. The computed results suggest that a developed 3 lb free-piston power saw will produce 1.0 hp at 6,400 cpm and have a specific fuel consumption of .9 lb/shp-hr. / Applied Science, Faculty of / Mechanical Engineering, Department of / Graduate

There is no abstract available for this thesis.

Thesis (M. App. Sc.)--University of Adelaide, Dept. of Mechanical Engineering, 1990. / Some mounted ill. Includes bibliographical references (leaves 48-50).

Thesis (M.Eng.Sc.) -- University of Adelaide, Dept. of Mechanical Engineering, 1983. / Typescript (photocopy).

Thesis (Ph. D.)--Carleton University, 1993. / Also available in electronic format on the Internet.

The results of this work will be useful to those interested in predicting or improving the cutting accuracy of guided circular saws. In this thesis an experimentally verified numerical model of the guided fixed collar circular saw is presented. Features of the model include the ability to represent the blade and collar geometry, blade runout, rotational stresses, guide dynamics, guide pad shape, guide lubricant, and guide or blade misalignment. The blade is assumed to be governed by thin plate theory and the guide arms are modelled as a lumped parameter system. The lubricating fluid is modelled as a number of massless spring-dampers. Numerical solutions are given for the natural frequency response, the forced response due to static or harmonic lateral loading, and for the self-excited response caused by the interaction of the blade runout with the guides. The behaviour of the runout as a function of blade rotation speed and the conditions for which a resonant condition is produced in the guides are also determined. Experimental results obtained for the natural response, the deflection caused by a static load, the effect of speed on the blade runout, and the self-excited response correlate well with the numerical results. Numerical results are presented to show the effects of guide position, guide shape and the use of multiple guides on the natural and forced response. / Applied Science, Faculty of / Mechanical Engineering, Department of / Graduate

No description available.

No description available.

This study investigates the dynamics of circular saws at supercritical speeds. A classical governing equation of a circular saw subjected to transverse and membrane forces is derived in both body-fixed and space-fixed coordinate systems. The transverse loads are generalized as spring, damping and out of plane cutting forces, and the membrane loads include rotational, thermal and in-plane cutting forces. Galerkin's Method is used to study the natural and forced response of a saw blade, and the effects of spring and damping on the stability at supercritical speed are discussed. An idling experiment is conducted to comprehend the fundamental behavior of circular saws at supercritical speed. The natural frequency, the steady state response, the flexibility and the runout variation of the circular saws are measured. The nonlinear vibration of the thin blade is observed. The effects of a spring-damper system and heating on the stability of a circular saw are investigated. A cutting test is conducted to find out the dominant parameters of supercritical speed cutting. At first, the prehminary experiments of the standard blade are conducted. Then, tip side cutting marks are discussed, and finally, the phenomenon of unstable cuttings are presented. The general solution of a rotating string subject to an elastic constraint is developed. Based on this, the discrepancy between theoretical and experimental stability results is analysed for a guided rotating disk. / Applied Science, Faculty of / Mechanical Engineering, Department of / Graduate

This study investigates some of the basic dynamic problems in the use of handsaws in industry. As the main purpose in bandsaw study is to understand and improve the cutting performance of the sawblade, this study emphasizes those dynamic problems that most affect the sawblade performance. These include the bandsaw structural dynamics, the top wheel dynamics, the global behavior of sawblades, and the washboarding problem in cutting. The study of bandsaw structural dynamics investigates the possible structural modes affecting the performance of the sawblade. Three structural modes within a frequency range of interest from 0 to 60 Hz were found and analyzed. The corresponding critical structural elements are indentified. The role of top wheel straining mechanism in bandsawing is discussed in the study of top wheel dynamics. Top wheel displacement during cutting and its effect on the performance of the sawblade are also investigated. The causes of top wheel displacement are the speed change of handsaws and temperature rise of the sawblades. In the global behavior of sawblades, the sawblade between the guides is modelled as a narrow, axially moving, thin beam with end loading. The Euler's equation of motion is developed by applying Hamilton's Principle to the model. A simplified finite element method by using a modified cubic beam element is used to solve the eigenproblem. These results are verified by tests with an idling sawblade. A finite element approach capable of calculating the natural frequencies and mode shapes is obtained. The washboarding phenomenon is investigated. Extensive experimental results are obtained and an analysis of the resulting washboarding is presented. Two types of wash-boarding have been observed and identified with the tooth impacting problem and the chatter vibration problem. The results of this study will be of interest to those who wish to improve their understanding of the dynamic behaviors of bandsaws and also to improve the performances of handsaws. / Applied Science, Faculty of / Mechanical Engineering, Department of / Graduate