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Articles 1 - 15 of 15

Full-Text Articles in Mechanical Engineering

Improving The Throughput Of Plasticating Extruders : Manufacture Of Non-Circular Pellets, Measurement Of Their Interparticulate Friction Coefficient, And Implications For Screw Design, Chia-Ying Liu Dec 1991

Improving The Throughput Of Plasticating Extruders : Manufacture Of Non-Circular Pellets, Measurement Of Their Interparticulate Friction Coefficient, And Implications For Screw Design, Chia-Ying Liu

Dissertations

This dissertation addresses the hypothesis that the interparticulate friction coefficient of a bed of polymeric particulates is a function of the cross-section of the pellets. Most pellets have a circular cross-section especially those that are strand cut. But when such pellets constitute a particulate bed there are few restrictions to adjacent pellets turning with respect to each other, or of the beds rupturing under shear load. This rupture can occur in plasticating extrusion, and it results in a poorly mixed melt with an inhomogeneous temperature distribution. The temperature fluctuations cause viscosity fluctuations which in turn cause pressure fluctuations. The pressure ...


Redesign Of Parts And Simulation Of Flexible Assembly Cell For Safety Water Shower Assembly, Balraj Y. Gardilla Dec 1991

Redesign Of Parts And Simulation Of Flexible Assembly Cell For Safety Water Shower Assembly, Balraj Y. Gardilla

Theses

A Design for Assembly (DSA) method is used to analyze the safety water shower assembly and to redesign the components with emphasis on meeting the criteria of allowing for flexible Assembly Cell (FAS). An Expert System is developed to select the right Assembly using VP-Expert. This thesis contrasts the old and new safety water shower assembly designs and describes the design of a final Flexible Assembly Cell. A PUMA 550 robot was investigated for use in the cell design. The flexible Assembly cell is simulated on silicon graphics using the IGRIP software. The economics of each part presentation method is ...


On Local Stresses And Spring Constants Of A Sphere-Nozzle Connection, Ban-Li Lyow May 1991

On Local Stresses And Spring Constants Of A Sphere-Nozzle Connection, Ban-Li Lyow

Dissertations

This dissertation studies the local stresses and spring constants of a spherical shell with a nozzle attachment when it is under various loadings, namely radial force, overturning moment, horizontal shear force, and torsional moment. Because of the mathematical difficulty in modeling the nozzle-sphere configuration, particularly with nozzle opening, the finite element method (ANSYS package) is utilized in this study. The model used in this study is a quadrilateral thin shell element model when the γs (spherical radius/thickness) value is larger than 10. Otherwise the isoparametric solid element is used. The resulting stresses are basically biaxial state of stresses ...


Size Reduction Of Polymeric Particulates By Jet Milling, Cheng Hua May 1991

Size Reduction Of Polymeric Particulates By Jet Milling, Cheng Hua

Theses

A basic theory for the size reduction operation by jet milling has been developed.

Typical samples of feedstock have been analyzed using screen analysis to determine the initial distribution of polymeric particulate sizes prior to jet milling.

A statistical theory .was developed using probabilities to represent the likelihood that specific size reductions would occur. These probabilities include the effects of various equipment.

The theory was then used to predict the distribution of polymeric particulate sizes after jet milling. The agreement between the predictions and actual results was within 5 %.

Encouraged by the successful work of the simulation of the process ...


Design For Manufacturability, Kocherlakota Sreedhar May 1991

Design For Manufacturability, Kocherlakota Sreedhar

Theses

Design for Manufacturability represents a new awareness of the importance of design as the first manufacturing step. It recognizes that a company cannot meet all its objectives with isolated design and manufacturing operations. The Design for Manufacturability approach embodies certain underlying imperatives that help maintain communication between all components of the Manufacturing and Design system and permit flexibility to adopt and to modify design during each stage of the product realization. Design for Manufacturability cannot be bought or sold and it should be implemented by management. Complete support of management to the implementation is very important to the success of ...


Off-Line Programming Using Igrip, Narahari K. Bhandary May 1991

Off-Line Programming Using Igrip, Narahari K. Bhandary

Theses

AT&T's FWS-200 (Flexible Work Station) has been modeled and simulated to implement Off-Line Programming (OLP). IGRIP (Interactive Graphics Robot Instruction Program) from Deneb Robotics, Inc. has been used to simulate the FWS operation. A GSL(Graphics Simulation Language) program has been used to simulate the chip placements during PCB assembly. The program leads the user through the motions of chip placement, and after the simulation run downloads the motion sequence to the FWS. The animation sequences of the FWS have been downloaded to the FWS on the Factory Floor using a C program, which is utilized to communicate ...


Development Of A Classification And Coding System For Computer-Aided Process Planning, Shilpan K. Patel May 1991

Development Of A Classification And Coding System For Computer-Aided Process Planning, Shilpan K. Patel

Theses

The chore of this work was to develop a Group Technology Classification Code which can represent the full gamut of simple, rotational parts. The automated coding plan is developed to alleviate the endeavor of the process planner to plan the tasks related to the manufacturing of a specific part. The 15 digits were devised from the Japanese KK-3 Classification and Coding system. The KK-3 System contains 21 digits. Our aim is to minimize the code length, and concurrently to eliminate the redundancies. As a result, a 15 digit G.T. Code is created. The proposed plan also generates the operation ...


Dynamic Analysis Of The Generalized Slider Crank, Sahidur Rahman May 1991

Dynamic Analysis Of The Generalized Slider Crank, Sahidur Rahman

Theses

A numerical technique is used to analyze the kinematics of the generalized slider crank mechanism and an analytical technique to derive dynamic force equations for that mechanism has been formulated. The numerical technique used for displacement analysis is based on a combination of Newton-Raphson and Davidon-Fletcher-Powell optimization algorithm using dual-number coordinate-transformation matrices. Velocity analysis is performed by using a dual number method. Finally, dynamic force analysis is accomplished on the basis of the dual-Euler equation and D'Alembert's principle. The approach is developed in such a manner that a digital computer can detect when a solution is possible and ...


Petri Net Modeling And Analysis Of An Fms Cell, Paresh A. Patel May 1991

Petri Net Modeling And Analysis Of An Fms Cell, Paresh A. Patel

Theses

Petri nets have evolved into a powerful tool for the modeling, analysis and design of asynchronous, concurrent systems. This thesis presents the modeling and analysis of a flexible manufacturing system (FMS) cell using Petri nets. In order to improve the productivity of such systems, the building of mathematical models is a crucial step.

In this thesis, the theory and application of Petri nets are presented with emphasis on their application to the modeling and analysis of practical automated manufacturing systems. The theory of Petri nets includes their basic notation and properties. In order to illustrate how a Petri net with ...


Design For Assembly : Re-Design Of An Electrical Switch For The Ease Of Automatic Assembly, Achyuta Reddy Pannala May 1991

Design For Assembly : Re-Design Of An Electrical Switch For The Ease Of Automatic Assembly, Achyuta Reddy Pannala

Theses

A design for assembly (DFA) method is used to analyze the existing design of parts of an electrical switch, and to reduce and re-design them, for the ease of automatic assembly. The procedure for the selection of suitable and economical assembly method is presented based on the Boothroyd & Dewhurst methods. Analysis of the initial design for manual assembly and the re-design for automatic assembly are presented. An algorithmic approach for simplified generation of all mechanical assembly sequences and selecting the good assembly sequences is presented with graphical representations. A work station needed for the automatic assembly is developed, which incorporates ...


Design For Manufacturability : Re-Design Of Pencil Sharpener For The Ease Of Assembly, Amit R. Rathod May 1991

Design For Manufacturability : Re-Design Of Pencil Sharpener For The Ease Of Assembly, Amit R. Rathod

Theses

A Design For Manufacturability (DFM) approach is used to analyze the existing design of a pencil sharpener, and to reduce and re-design the parts of pencil sharpener for the ease of assembly. The procedure for the selection of a suitable and economical assembly method is based on the Boothroyd and Dewhurst methods. Analysis of the initial design for manual assembly and re-design for automatic as well as manual assembly is presented. An algorithmic approach for simplified generation of all mechanical assembly sequences and selection of the assembly sequences is presented using De Fazio and Whitney approach.


Effect Of Shrinkage On The Design And Manufacture Of Plastic Parts In Injection Molding Using Cad/Cam Techniques, Deepak M. Shastri May 1991

Effect Of Shrinkage On The Design And Manufacture Of Plastic Parts In Injection Molding Using Cad/Cam Techniques, Deepak M. Shastri

Theses

Computer aided design software in injection molding has revolutionized injection molding in the design and manufacturing processes. Computer Aided Engineering can be applied to injection molding to increase the process efficiency, reduce part costs, and produce accurate parts in less time. The mold designer has many software programs to choose from to produce satisfactory mold designs from part geometries, and a correct selection can produce profitable results. A study of the need for and the scope of computers in injection molding is performed to evaluate the suitability of a CAE package by considering the value added to the parts using ...


Implementation Of Automated Assembly, Kang H. Kong May 1991

Implementation Of Automated Assembly, Kang H. Kong

Theses

Research has shown that about 60 - 80% wealth producing activities is related to manufacturing in major industrial countries.

Increased competition in industry has resulted in a greater emphasis on using automation to improve productivity and quality and also to reduce cost.

Most of the manufacturing works such as machining, painting, storage, retrieval, inspection and transportation have changed to automation successfully, except assembly. Manual assembly is predominant over automatic assembly techniques due to inherent assembly problem and the fact that the assembly machines lack the innate intelligence of human operator and lack sufficient flexibility to changeover when product designs and market ...


Investigation Of Stagnation Flow Heat Transfer For A Heated Horizontal Round Plate, Ching-Hua Wei May 1991

Investigation Of Stagnation Flow Heat Transfer For A Heated Horizontal Round Plate, Ching-Hua Wei

Dissertations

The heat transfer characteristics in stagnation flow are investigated through three cases in this study. The first is forced convection by an array of air jets; the second is free convection of a downward-facing heated round plate; the third is free convection of an upward-facing heated round plate.

The first case is investigated by systematic experiments which examine the heat transfer characteristics mainly by five air jets impinging normally to a flat plate, with varying nozzle diameters, and Reynolds numbers, at different distances between the nozzles and the plate. The empirical formulas of heat transfer around the stagnation point and ...


Computer-Aided Process Planning (Capp) Sorich, Sohail Pirzada Jan 1991

Computer-Aided Process Planning (Capp) Sorich, Sohail Pirzada

Theses

The last two decades have witnessed the increasing role of the computer in the process planning function. This has been further enhanced by the advent of the knowledge based expert system, and its impact on Computer Aided Process Planning (CAPP). CAPP has emerged as a strategic link between design and manufacture. This thesis discusses the various methods used in the process planning function. Group Technology (GT) plays a pivotal role in establishing CAPP. The utilization of Artificial Intelligence techniques in CAPP is listed. This study also presents an Interactive Software adaptive to product/part configuration variables.