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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Fixture planning in a feature based environment

Chia, Ser Chong January 1997 (has links)
Fixtures are used to constrain workpieces during machining processes. Fixtures locate and hold the workpiece in position and ensure that it is in a state of equilibrium, and that dimensional accuracy is maintained throughout the manufacturing operation. Traditionally, design and manufacturing problems were solved by means of a sequence of design and planning stages followed by manufacturing. However, the recent emergence of Concurrent Engineering has prompted companies to solve the problems in parallel. The availability of data in a concurrent engineering environment places great emphasis on process planning. Fixture planning being part of process planning therefore becomes one of the most important aspects of Concurrent Engineering. The decline in the number of experienced fixture designers, the long lead time for traditional manual design, the rapid progress in the field of Computer Aided Engineering as well as the introduction of Concurrent Engineering are some of the main factors which have motivated researchers to develop automated fixture design systems in recent years. This thesis reports on the development and implementation of FixPlan. FixPlan is a fixture planning system that consists of three separate modules; a Featured Based Design System (FBDS), a Geometric Reasoner (GR), a Fixture Planner (FP). The FBDS module allows the engineer to design components with features such as blanks, holes and pockets. The GR module enables the system to interrogate and analyse the product model and is used extensively by both the FBDS and FP modules. The FP module generates and sequences the set-ups required, selects the positioning, supporting and clamping faces as well as their corresponding points and select the appropriate fixture element of each of the points. Geometrical relationships between features in the product model are used to determine the number of set-ups required as well as their sequence. FixPlan demonstrates the possibility of automating the fixture planning processes and its interrogation with other process planning systems. The main strength of FixPlan lies in its ability to interrogate and analyse the product model through the use of geometric reasoning. The system is unique as it utilises a fully embedded 3D solid modelling representation of the parts to enable spatial reasoning functions.
2

Modelling of the cutting process when machining hardened steel with polycrystalline cubic boron nitride(PCBN)tooling

Ng, Eu-Gene January 2001 (has links)
No description available.
3

The design of tooling for the vertical isostatic dust pressing process

Wolfe, Robert Anthony January 2003 (has links)
No description available.
4

The dynamics of electrohydraulic cylinder drives

Pennington, A. De January 1971 (has links)
No description available.
5

The prediction of the dynamic characteristics of machine tool structures

Cowley, A. January 1968 (has links)
No description available.
6

Hexapod machines : stiffness analysis, simulation & design

Chen, Jiqing January 2004 (has links)
No description available.
7

A sensorless induction motor drive employing an artificial neural network for on-line parameter adaption

Campbell, James Alastair January 2001 (has links)
No description available.
8

Modelling of an ultrasonically assisted drill bit

Thomas, Peter January 2008 (has links)
No description available.
9

Abrasive machining with MQSL

Morris, Tom January 2011 (has links)
Grinding and polishing of engineered components are critical aspects of the precision manufacturing of high performance, quality assured products. Elevated process temperatures, however, are a common and for the most part undesirable feature of the grinding process. High process temperatures increase the likelihood of microstructural change within the immediate subsurface layer and are detrimental to the strength and performance of the manufactured products. Increasing processing costs and tighter environmental legislation are encouraging industry to seek innovative fluid application techniques as significant savings in production can be achieved. In this context, and with sponsorship from three industrial partners, namely; Fives Cinetic, Fuchs Lubricants plc and Southside Thermal Sciences Ltd, and also from the Engineering and Physical Science Research Council (EPSRC), this research aimed to develop an understanding of Minimum Quantity Solid Lubrication (MQSL) as a method for abrasive machining, with particular reference to the control of surface temperatures. Improving the lubricity of Minimum Quantity Lubrication (MQL) fluids reduces the frictional source of process heat and controls the finish surface temperature. The application of effective solid lubricants is known as Minimum Quantity Solid Lubrication (MQSL). Molybdenum Disulphide (MoS2), Calcium Fluoride (CaF2), and hexagonal Boron Nitride (hBN) were compared against a semi-synthetic water soluble machining fluid (Fuchs EcoCool). A series of Taguchi factorial experimental trials assessed their performances through ANOVA (ANalysis Of VAriance) statistical method. The hBN produced the lowest grinding temperatures of the solid lubricants tested, although they still remained higher than those achieved using the EcoCool control. The reduction of the machining fluid enabled a Charged Coupled Device (CCD) sensor to be fitted into the grinding machine. The recorded movement in the emitted spectrum from the grinding chips was compared to experimental and modelled process temperatures. This showed that the wavelengths of the chip light correlated to the temperature of the finish grinding surface. This greatly contributed to determining the feasibility of constructing a non-destructive, non-invasive, thermally-adaptive control system for controlling grinding surface temperatures.
10

Assessment and compensation of errors in CNC turning

Mladenov, Dimitar M. January 2002 (has links)
No description available.

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