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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

Structural modelling and control of job-flow in manufacturing systems

Otolorin, O. January 1982 (has links)
No description available.
2

An investigation into the operation of an Order-Handling-Manufacturing System

Wu, B. January 1988 (has links)
No description available.
3

Computer aided design of a press tool run-off

Harrison, Keith January 1990 (has links)
This thesis is concerned with the design of press tool run-ofts. Run-off is the area on the punch surrounding the panel and its shape is of great importance to the control of metal flow during the draw. The design, although influenced by engineering considerations, is principally a geometric problem, which traditionally has been time-consuming. The overall objective is to reduce the run-oft definition time and hence improve the lead time. Current Austin Rover design procedures are described in Chapter 2 and form the basis of the C.A.D. program outlined in Chapter 3. This specification distils the need for a number of geometric algorithms. In general, obtaining the required continuity between the panel and run-off surface will require some degree of boundary curve approximation. Chapter 4 details four alternative approximation techniques which are compared in Chapter 5; and constitute the main results of the thesis. The salient issues of run-off surface interpolation are considered in Chapter 6.
4

Heat transfer in rotary cement kilns

Jenkins, Barrie George January 1977 (has links)
The results of an extensive series of trials on a 100 tonnes per day cement kiln have provided a fundamental insight into the aerodynamics, burning mechanism and heat transfer in the sintering zone of such kilns. Accurate monitoring of the input and output variables has enabled mass and heat balances to be made on the system, and from these results it has been possible to isolate the areas where major fuel savings can be achieved. Slurry moisture, excess air and external heat losses are all variables where improvements and better control would reduce fuel consumption and increase the efficiency of rotary kilns. It has been shown that the external temperature profile of the kiln shell provides a useful indication of the various reaction regions that exist in the process cycle. From calculations of the heat lost from the shell, it has been shown that half the external heat losses occur from the sintering zone of the kiln. Specialized instrumentation has been developed to measure gas temperatures and extract combustion gas samples during the normal range of operation of the kiln. An analysis of these results has led to a formula to predict the length of the flame as influenced by the significant operating parameters. The measured gas concentrations have been used to predict the combustion rate within the flame, and a favourable comparison of this rate has been made with published data. The measurement of flame temperatures in the kiln has shown that the average flame temperature that may be encountered in a cement kiln is approximately 1800°C. Point temperatures of up to 2100°C were measured, and it was observed that increased excess air produced a shorter, hotter flame, but reduced the temperature of the combusted gases, resulting in a poorer quality product. A mathematical model has been developed to predict the gas and refractory temperature and heat flux profiles occurring in a rotary kiln sintering zone. The method is based on that of Hottel and Sarofim, but modified to account for the specialised firing conditions necessary for cement production. The model has been tested against the measured data obtained from the kiln trials, and the degree of agreement found to be encouraging. Use of this model should enable the cement, lime, and refractory industries to comprehend the effect of changes to operational variables, with a resulting improvement in heat utilisation, product quality and plant life.
5

A graph grammar based approach to automated manufacturing planning

Fu, Wentao 26 July 2012 (has links)
In this thesis, a new graph grammar representation is proposed to reason about the manufacturability of solid models. The knowledge captured in the graph grammar rules serves as a virtual machinist in its ability to recognize arbitrary geometries and match them to various machine operations. Firstly, a novel convex decomposition algorithm has been developed to decompose a given part into multiple sub-volumes, where each sub-volume is assumed to be machined in one operation or to be non-machinable. Then the decomposed part is converted into a graph so that graph grammar rules can determine the machining details. A candidate plan is a feasible sequence of all of the necessary machining operations needed to manufacture this part. If a given geometry is not machinable, the rules will fail to find a complete manufacturing plan for all of the sub-volumes. As a result of this representation, designers can quickly get insights into how a part can be made and how it can be improved based upon the feedback of the rules. A variety of tests of this algorithm on both simple and complex engineering parts show its effectiveness and efficiency. / text
6

Processförbättring för tillverkandet av specialbalk / Improvement of the manufacturing process for purlins

Ansheden, Caroline January 2010 (has links)
Examensarbetet genomfördes åt företaget Corus Byggsystem AB. Ett företag placerat i Halmstad som tillverkar profilplåt och lättbalk till tak och fasader. Företaget erbjuder även god rådgivning och skapar optimala lösningar för kunden. I företagets produktion finns det en maskin som pressar specialbalkar. Denna arbetsplats är varken produktionseffektiv eller ergonomiskt riktig då materialet och balkarna lyftes manuellt, i vissa fall även över huvudet. På tunga arbetsplatser är det oerhört viktigt att se över ergonomin, både för att förbättra säkerheten och för att öka produktionsvolymen. Fokus lades därför vid att förbättra arbetsplatsen ergonomiskt för att resultera i ett säkert och produktionseffektivt resultat. Som metod har tre olika varianter använts. Främst Ullmans metod The Mechanical Design Process och Fredy Olssons Primär- och Principkonstruktion. Även SVID’s Designprocess har funnits väl till pass. / This thesis work has been conducted for Corus Byggsystem AB. The company is located in Halmstad and manufactures profile claddings and purlins from sheet metal. The company also offers the customers professional advice and creates optimal solutions. In the production there is a press brake that manufactures purlins. This work station has neither efficient production or is ergonomically correct. The material and purlins are lifted manually by the workers and in some cases over the head. For heavy work, it is extremely important to apply an ergonomic approach, both to improve security for the workers and to increase the manufacturing volume. The focus was therefore on how to improve the workplace ergonomically to result in a safe workplace with efficient manufacturing results. The method that was mainly used in this project was David G. Ullmans The Mechanical Design Process and Fredy Olssons Primärkonstruktion and Principkonstruktion. Also SVID’s Design Process has been used as support.
7

Piezoelectric Inkjet Printed Aluminum Bismuth (III) Oxide: The Effects of Printing Parameters on Burning Rate

Forrest J. Son (5930867) 16 January 2020 (has links)
This thesis presents work on the deposition of nanothermite using a piezoelectric inkjet printer, focusing on the effects of printing parameters and sample geometry on burning rate. The ability of the printer to produce consistent droplet size and spacing was shown to have repeatable droplet size and sub-millimeter precision in droplet spacing. The droplet-droplet interaction of the nanothermite ink was examined, and a printing frequency of 10 Hz was shown to produce smooth and consistent geometry in the printed samples. The primary printing parameter varied in this study was the pixel pitch (i.e., the distance between printed droplets). As pixel pitch decreased (i.e., the droplets are printed closer together) in both directions (x- and y-directions), the burning rate increased, and as sample width increased the burning rate increased. A significant number of samples (476) were printed and demonstrated consistent, energetic performance; this indicated favorable high-volume production capabilities. A thermal model was developed based on an energy balance for the printed nanothermite samples. The model accurately predicted the burning rate trends observed in the experimental results. This result indicated that the increase in heat generation in both the thicker (pixel-pitch studies) and wider samples decreased the significance of heat loss to the environment. The statistically significant results presented in this work, along with a descriptive thermal model, increase the fundamental understanding of the effects of printed geometry and droplet spacing on nanothermite energetic performance.
8

A Numerical and Experimental Investigation of Steady-State and Transient Melt Pool Dimensions in Additive Manufacturing of Invar 36

Obidigbo, Chigozie Nwachukwu 01 September 2017 (has links)
No description available.
9

Micro Molding Process Monitoring and Control

Whiteside, Benjamin R., Babenko, Maksims, Brown, Elaine C. 03 May 2019 (has links)
No
10

Analysis of defects associated with leaks on skid steer loaders

Imel, Clint J. January 1900 (has links)
Master of Agribusiness / Department of Agricultural Economics / Ted C. Schroeder / The CNH Wichita Product Center has had a chronic leak problem with the Skid Steer Loaders. The objective of this project was to analyze the manufacturing plant leak data and make improvements to correct the issue. The objective is twofold: 1) to make process or design improvements on current products produced in the plant and 2) to make recommendations for future designs to prevent such leak issues from reoccurring. The manufacturing data had to be transformed into usable form and then it was analyzed mostly by utilizing Pareto Charts. The highest six problem leak points were chosen from the manufacturing data. Process changes were implemented on these particular leak joints and the results were analyzed using two proportions hypothesis tests. The process changes reduced the leak rate by an average percent reduction of 86 percent. The process changes implemented will also be applied to other similar joints, and results documented in the future. The future design recommendations made from the analyzed data included the increased use of o-ring face seal connections at certain locations and where possible, reducing the number of joints per machine.

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