<p>A realistic relationship between cam and follower motion is developed taking into full account the effect of manufacturing errors as defined by the specified error bound of the tolerances and clearances. Probability theory is used, and a general computer program has been developed to obtain the motion relationships and the effects of these equal errors on the standard cam motion programs are compared.</p> / Master of Engineering (ME)

<p>A lightweight manipulator has many desirable features. The structural flexibility associated with lightweight manipulators often results in mechanical vibrations and consequently leads to long settling times and position inaccuracy. The aim of the current study is to investigate the dynamics of a two degree of freedom manipulator with elastic joints and very flexible arms and develop a proper control strategy. The dynamic model of manipulator is derived with the Lagrangian formulation and the assumed-modes approach. The eigenvalues and eigen-functions of the flexible arms are determined by the transfer matrix method. The dynamic effects of friction at the joints, gear blacklash within the actuation, and internal structural damping of the arms are all considered. The derived theoretical model is verified by experiments.</p> <p>The parametric analysis is to designed to examine the effects of the major system parameters on the dynamic performance of the manipulator. The dynamic interactions between the members of the manipulator are also investigated.</p> <p>The power balancing technique is extended for distributed parameter systems and a new approach for model order reduction of nonlinear systems is proposed. Using the derived power elements of the original system states as a criterion, the model reduction is performed in the original physical coordinates. The proposed technique is applied to the manipulator. It is found that the bending vibrations of the flexible link are dominated by its first two natural modes. The contributions of the higher modes are negligible.</p> <p>A model reference adaptive control algorithm originally developed by Sobel is modified and used for the control of manipulator with an unknown payload. It is shown that the modification improves the algorithm's performance significantly. Computer simulations are performed to examine the algorithm's properties and select proper values for the gain matrices. Real-time testing is implemented to validate the theoretical analysis. It is found that the proposed algorithm provides satisfactory performance of the closed-loop system.</p> / Doctor of Philosophy (PhD)

<p>Advances in the aerospace and automotive industry have led to the introduction of many new shapes with complex geometries. These shapes are typical of turbine blades, as well as molds and dies. The manufacturing of these geometries consists of automatic tool path generation for multi-axis computer numerically-controlled machining centers. The conformity of the manufactured geometry to the design requirements depends on several factors. These involve cutting tool selection, positioning of the cutting tool, as well as the avoidance of collision and gouging between the cutting tool and the workpiece. This dissertation presents a solid modeling-based approach for tool geometry selection, the simulation and optimization of five-axis tool path generation, as well as gouge and collision avoidance for manufacturing sculptured surfaces. A methodology for tool path generation and checking for the flank-milling of operation is also developed. An optimization algorithm is developed to re-distribute tool path points according to their effect on the geometry of the manufactured surface. A new algorithm to determine tool inclination is also developed based on an effective tool profile and curvature matching techniques. A cusp height control approach is developed based on feasible tool inclinations, and step-over distance evaluation. An algorithm for tool path generation and gouge as well as collision avoidance is developed. A flank milling tool path planning and checking algorithm is developed based on the optimization of the tool path advancement scheme according to the surface topology. A new multi-stage tool model refinement approach was developed, and integrated with the algorithms that constitute this work. Experimental validation of the presented algorithms is carried out to test the cusp height, and smoothness of the tool orientation transition. A comparison between the presented algorithms and state of the art CAM commercial software is also presented. The validation results showed that the developed approach can give more accurate results. The results of this work are intended to fill the shortcomings encountered in the previous research on five-axis machining of sculptured surfaces. These are: cutting tool selection; tool path points optimization, cusp height control, tool position and orientation optimization, and flank-milling.</p> / Doctor of Philosophy (PhD)

<p>A computer-aided design system (FBAR) has been developed which is capable of solving four-bar coupler position problems. This system can handle theoretically any number of positions of the coupler link and allows the designer to exercise his judgement in the design process by making use of the computer and the graphical display.</p> <p>The theory is based on a multifactor optimization of two dependent design variables (errors in the coupler point coordinates and in the coupler link orientation) and by imposing constraints to ensure that a proper four-bar mechanism is obtained.</p> <p>At present the synthesis program of the system is run on a CDC 6400 computer in a timesharing mode and the graphical analysis program is run on a PDP11/34 mini-computer. The final aim would be to make it a single system through a satellite graphics approach.</p> <p>FBAR, the software system, has been tested for all types of the four-bar mechanisms (i.e., crank-rocker, double-crank and double-rockers) with the number of prescribed positions of the coupler link varying from three to nine.</p> / Master of Engineering (ME)

<p>This study describes the results of experiments on the pumping of non-Newtonian bentonite clay slurries. The data were obtained from smooth tubes having internal diameters of 0.60 cm, 1.27 cm and 1.74 cm, for aqueous suspension concentrations of 1.96, 4.0, 5.0, 6.0 and 8.0% by weight. The flow Reynolds numbers varied to a maximum of about 6000. Shear stress-shear rate curves were obtained as well as apparent viscosity and generalized Bingham plastic plots. Specific power was plotted against Reynolds number for all concentrations. It was found in general that the data of the shear curve agreed quite well with that from other sources but that there were discrepancies for the Bingham plastic equation. The fact that Newtonian friction factor curves for flow in smooth pipe can be used in conjunction with bentonite slurries in an equilibrium state was also demonstrated.</p> / Master of Engineering (ME)

<p>This thesis is concerned with the flow phenomena associated with the hydraulic transport of spherical and cylindrical capsules in a 7.6 cm-diameter vertical pipeline.</p> <p>In the experiments, spherical capsules of steel, aluminum and nylon of capsule/pipe diameter ratio d/D = 0.57, 0.65 and 0.82 were investigated. Also, right circular cylinders of aluminum and nylon of d/D = 0.49, 0.65, 0.82, and capsule length/diameter ratio L/d = 4, 7, 10, 14 were investigated. The steady-state capsule velocity Vc and the pressure gradient associated with the capsules were measured. Based on the measured results the velocity ratio Rv, the pressure gradient Rp and the unit energy requirements P for the capsules were calculated. The effects of the individual pertinent variables which affect Rv, Rp and P as indicates by the experiments were discussed.</p> <p>Furthermore, theoretical and semi-empirical correlations between Vc, (ΔP/L)c and the pertinent variables of the systems were derived.</p> / Master of Engineering (ME)

<p>The local and global phenomena in oscillatory steam flow reflux condensation were investigated both experimentally and theoretically.</p> <p>A series of experiments were carried out in a 4.86m long vertical double-pipe condenser consisting of a 1.735cm diameter inner tube enclosed within a 5cm diameter outer tube. Four different inlet steam flow square-wave modulation frequencies: 0 (steady state), 0.05Hz, o.1Hz, and 0.2Hz, and a constant cooling side inlet temperature and flow rate of 30°C and 1kg/min respectively, were investigated. The experiments covered an average steam flow rate range of 10-300g/min, an amplitude range of 0-150g/min, and flow bias levels of 10-300g/min. These experiments were designed to investigate the effects of frequency, amplitude, and bias (steady component) of the inlet steam flow modulation on the observed process.</p> <p>Five different operating modes were identified in the condenser as the inlet mass flow rate was increased. The operating modes, categorized according to the observed flow regimes in the condenser, were: (1) reflux condensation without water column mode, (2) reflux condensation with water column mode, (3) first carry-over mode, (4) second carry over mode, (5) climbing film flow mode. Complete reflux condensation was maintained only in the first two modes of operation.</p> <p>Under steady inlet steam flow conditions, it was found that the flooding in the tube caused the system to undergo transition from the first mode of operation to the third mode of operation at very low inlet steam flow rates, thereby severely limiting the condensation capacity in complete reflux condensation. Under modulated steam flow conditions, and depending on the particular combination of frequency, amplitude, and steam flow bias, as much as 300% improvement on the condensation capacity was obtained. In general, improvement in the condensation capacity was favored by low frequency, high amplitude, and low to moderate steam flow bias levels.</p> <p>Observations of the experimental phenomenon showed that once flooding occurred in the tube under steady inlet steam flow conditions, the resulting net upward condensate flow led to the formation and build-up of single-phase condensate (water column) on top of the condensing region. The back pressure exerted by this water column on the condensing region upstream led to a huge increase in the operating pressure and overall pressure drop across the condenser tube, which was directly reflected in the measured operating pressure. Experimental results showed that substantial reductions in the time-averaged system pressure and pressure drop across the condenser were achieved under modulated steam flow conditions, due to the tendency of the oscillations in the steam flow to destabilize the water column or prevent sustained water column formation and growth. Under modulated steam flow, the system pressure was influenced mostly by the frequency of modulation and the steam flow bias, and to a lesser extent the amplitude of steam flow. These factors were found to play dual roles in the time-averaged overall pressure drop, as this pressure drop was found to play dual roles in the time-averaged pressure drop increased with both the frequency of modulation and the flow bias. Additionally the experimental results showed that in addition to the remarkable reductions in the overall pressure drop achieved with steam flow modulation, the relative amplitude in the system pressure introduced by flow oscillation was unexpectedly very small (the maximum value obtained in the present experiments was less than 4%).</p> <p>Experimental results of local wall heat fluxes showed that a significant part of the heat transfer augmentation achieved with steam modulation was due to condensate entrainment from the film, and more importantly from the water column where it existed. Estimates of water column entrainment rates made from experimental results revealed that extremely high entrainment ratios could be attained, depending on the amplitude of modulation. The high entrainment rates were manifested in the increased heat transfer rates around the water column region, due to the direct contact heat transfer made available by the interaction of the steam with the much colder water column. However, the local heat transfer under modulated steam flow conditions exhibited significant cyclic components, the magnitude of which depended on the minimum condensing region length (which was set by the steam flow bias and the amplitude in the inlet steam flow.</p> <p>A fully implicit seven-equation two-fluid model was specifically formulated to model the reflux condensation process as observed in the present experiments. The model was solved by employing a simple time-dependant dynamic grid adaptation technique designed to track the unknown and time-varying condensing region length. A set of empirical correlations for interfacial mass, momentum, and energy transfer selected from the literature and developed from the present experimental results were employed in the solution of the two-fluid model. The model was used to investigate the effect of the tube diameter, tube length, and cooling side flow rate and inlet temperature on the process.</p> <p>Numerical simulations of some of the present experiments, in the reflux condensation mode of operation, were carried out using the two-fluid model, but the model exhibited convergence problems in the presence of a water column, and so experiments in the second mode of operation could not be simulated with a reasonable degree of accuracy.</p> <p>Theoretical results obtained from the model showed that as the tube diameter increased the pressure drop per unit length of condenser decreased, and the inlet steam flow rate at flooding increased, or equivalently the condensation capacity or operating range of the condenser increased, With respect to the inlet cooling water temperature, the model results showed that the heat removal rates in the condenser increased as this temperature was decreased.</p> / Doctor of Philosophy (PhD)

<p>The machining of hardened steel is becoming widespread throughout the manufacturing industry owing to the benefits derived in the form of manufacturing flexibility, better product quality, and the prospect of dry machining. This coupled with developments in super hard cutting tool materials and machine tools, and better understanding of hard machining technology translates into significant economical benefits and faster turnaround times.</p> <p>The majority of applications involving hardened steels comprising AISI D2 tool steel relates to the manufacturing of die and mold wherein the current trend of hard machining is restricted by the limitations imposed by hard drilling. Being the final operation in many manufacturing applications, it is imperative that the process of drilling be robust and reliable to enhance the value already added to the product. Problems associated with inherent deficiencies in the drilling process kinematics, combined with poor machinability of hardened D2 tool steels due to the presence of hard and abrasive carbide particles in its microstructure that lead to catastrophic drill failure, constitute the single major process chain bottleneck in realizing hard part manufacture.</p> <p>The research work presented in this thesis focuses on the application of helical milling as an enabling technology for hole making in hardened AISI D2 tool steel in comparison to conventional drilling, which is not feasible at the current level of developments in drilling technology. Helical milling employs a rotating end mill of a diameter smaller than the hole, and traverses a helical path to generate a hole. The novel process derived by simple modification of tooling and process kinematics offers an excellent avenue to successful machining of precision holes in hardened D2 tool steel.</p> <p>In order to compare the performance of helical milling against drilling, four types of conventional twist drills intended for drilling hardened steels were employed in the machining experiments while, end mills commonly used in the die and mold industry, were chosen for helical milling. The processes were evaluated in terms of tool life, wear progression, wear mode, cutting forces and hole quality.</p> <p>Accelerated wear followed by catastrophic fracture of the cutting edges at the periphery of the drill was observed to be the primary tool failure mode in conventional drilling as opposed to uniform progressive flank wear in helical milling. The innovative helical milling method is found to facilitate1 hole-making in hardened D2 tool steel with an order of magnitude improvement in tool life. The helical trajectory of the tool in helical milling facilitates material removal near and at the center of the hole by cutting rather than extrusion as seen in drilling, thereby reducing the excessive thrust forces that cause work material breakouts at the hole exit in conventional drilling.</p> <p>Furthermore, chip evacuation in not problematic in helical milling considering that chips can be removed across the radial clearance between the tool and the hole as opposed to through the flute space in conventional drilling. This implies that an air blow could be employed to assist chip transport in helical milling facilitating dry machining, considering that in many drilling applications cutting fluid is merely used to flush the chips away from the cutting zone. The intermittent cutting action in helical milling further provides respite to the cutting edge from the imposed mechan ical and thermal loads and offers exceptional chip control. The process represents an enabling technology with additional benefits of superior hole quality thus rendering the elimination of an additional reaming process.</p> / Master of Applied Science (MASc)

<p>Launching new manufacturing systems for production is a difficult task which involves several people and resources, and is time-consuming and capital intensive. Flexible manufacturing systems (FMS), which are a new generation of manufacturing systems, further complicate this launching process because they consist of several interacting components such as workstations, pallets, automated material handling systems, and buffers. The lack of knowledge about the interaction between these components has often resulted in the poor performance of many FMS designs. Major corporations today are adopting a proactive philosophy rather than reactive one, and for a complex and capital intensive manufacturing system such as an FMS, the design process is extremely critical for its successful performance.</p> <p>The design process, which precedes the launching of an FMS, is iterative and consists of planning, model development, and output analysis. While several computer-based tools are available for modeling and evaluating FMS designs, here is a dearth of such tools for synthesizing new design and analyzing output from simulation models to improve these designs. System designers have traditionally performed these two activities using their knowledge and experience. These are cumbersome and time-consuming activities and consequently increase the design cycle time.</p> <p>The objective of this thesis is to reduce the FMS design cycle time by automating the design process. A knowledge-based system called FMX, Flexible Manufacturing Expert, was developed in this thesis to generate and evaluate designs of manufacturing systems with a high degree of automation. The object-oriented FMX is an intelligent system which combines expert systems and simulation modeling to design and evaluate flexible manufacturing systems. It consists of several modules, the major ones including an expert design synthesizer to generate initial system designs, a simulation models, and an expert analyzer to analyze simulation output, identity design deficiencies, and recommend changes. The current implementation of FMX was developed using the Knowledge Engineering Environment (KEE) expert system shell and the SimKit simulation package, and it runs on a Sun workstation under a UNIX operating system.</p> <p>FMX has been applied for designing flexible manufacturing systems in the machining domain. Two case studies have been included in this thesis to demonstrate its capabilities-one of which includes industrial system used by a major automotive manufacturer in Ontario. The first case study took two iterations while the second one took three iterations to fine tune a synthesized design that satisfied various performance measures such as production volumes, equipment utilizations, equipment blocking, and queue length of automatic pallet changers. For both case studies, the investment cost per part index decreased for each iteration thus proving that the design changes suggested by the expert analyzer improved the performance of the initial system design while reducing the cost. The final output from FMX is a list of components that comprise the system, its graphical layout, and its performance measures.</p> <p>FMX is a comprehensive decision support system which integrates all phases of a flexible manufacturing system design into a single software framework. Its modules such as the expert design synthesizer, simulation model developer, and expert analyzer each address a specific phase of the system design process. FMX generates consistent designs with the minimum intervention from the user and hence reduces the design cycle time significantly.</p> / Doctor of Philosophy (PhD)

<p>The dynamic behaviour of metal cutting process is investigated by measuring the various components of dynamic cutting force. For the complete description of dynamics of metal cutting it is necessary to give eight components belonging to the resultant dynamic cutting force in an orthogonal cutting process. These components originate from the two sides of chip, which under vibratory cutting conditions have undulations and are termed as inner and outer modulations respectively. The dynamic cutting forces are phase shifted with respect to their own modulations and are given respectively by real part and imaginary part of inner modulation, real part and imaginary part of outer modulation. Each of these four components are determined separately for main cutting force and thrust force and are specified as cutting force per unit amplitude of modulation per unit chip width, termed as dynamic cutting force coefficients. An experimental technique termed as the Double Modulation Method has been developed to measure the above eight coefficients for various cutting conditions of speed, feed, frequency, tool wear and work piece materials. The method is based on the Fast Fourier Transform of the measured signals of dynamic cutting forces and tool work piece relative displacement. The accuracy and reliability of the technique is established by comparing some of the results obtained from this method with those obtained from other two methods which are far simpler and conceptually more direct. These methods are termed as Kal's Method and Inner Modulation Method. The effects of various cutting conditions stipulated above on the individual coefficients have been investigated and the results are shown to be in agreement with the general practical observations. The result of stability analysis as performed by Moriwaki (21) using the coefficients measured in this work is included, to highlight the practical significance of the dynamic cutting force coefficients, for predicting the limit of stability.</p> / Doctor of Philosophy (PhD)