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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.
61

Service life estimations in the design of a PCM based night cooling system

Hed, Göran January 2005 (has links)
The use of Phase Change Material, PCM, to change the thermal inertia of lightweight buildings is investigated in the CRAFT project C-TIDE. It is a joint project with Italian and Swedish partners, representing both industry and research. PCMs are materials where the phase change enthalpy can be used for thermal storage. The Swedish application is a night ventilation system where cold night air is used to solidify the PCM. The PCM is melted in the day with warm indoor air and thereby the indoor air is cooled. The system is intended for light weight buildings with an overproduction of heat during daytime. In the thesis, the results of experiments and numerical simulations of the application are presented. The theoretical background in order design the heat exchanger and applying the installation in thermal simulation software is presented. An extensive program is set up, in order to develop test methods and carry tests to evaluate the performance over time of the PCM. Testing procedures are set up according to ISO standards concerning service life testing. The tests are focused on the change over time of the Thermal Storage Capacity (TSC) in different temperature spans. Measurements are carried out on large samples with a water bath calorimeter. The service life estimation of a material is based on the performance of one or more critical properties over time. When the performances of these properties are below the performance requirements, the material has reached its service life. The critical properties of the PCM are evaluated by simulation of the application. The performance requirements of the material are set up according to general requirements of PCM and requirements according to building legislation. The critical properties of a PCM are the transition temperature, the melting temperature range and the TSC in the operative temperature interval. The critical property of the application is its energy efficiency. The results of the study show that the night cooling system will lower the indoor air temperature during daytime. It also shows that the tested PCM does not have a clear phase change, but an increased specific heat in the operative temperature interval. Increasing the amount of material, used in the application, can compensate this. Finally, the tested PCM is thermally stable and the service life of the product is within the range of the design lives of the building services. It is essential to for all designers to know the performance over time of the properties of PCMs. Therefore it is desirable that standardized testing methods of PCM are established and standardized classification systems of PCMs are developed. / QC 20101020
62

Konceptförslag för detaljhantering i en svetsrobotcell / Concept for handling items to be processed by a welding robot

Hinders, Fredrik January 2009 (has links)
Abstract At the plant of Outokumpu Stainless Tubular Products AB in Molkom a wide range of butt weld fittings are produced. These are aimed mainly for the process industries and one of the products are ninety degree bend elbows in various dimensions. The elbows are made from stainless sheet metal and when formed to a tube they need to be welded along its inner radius. This is made by a pick and place type industrial robot working in a closed compartment. The assignment given by Outokumpu aims to investigate and suggest a new concept for a more reliable manufacturing process within the work cell.   The cell consists of five main areas chronologically listed as passed by the elbow: ·          Automated, vibrating conveyor.·          Fixture with the purpose to serve the robot with one elbow at a time, placed in the correct position.·          Industrial robot to pick up the elbow and drag it along the welding head.·          TIG inverter with a stationary welding head·          A hydraulic press with a template of the final shape of the elbow corrects flaws. Almost every problem in the cell and defects on the products coming out of it can be traced back to the fixture and in some cases also to the robots pick up tooling. The focus of the task was therefore put mainly on those two areas. As the work proceeded Outokumpu chose to develop a new tool for the robot themselves which they did with good results. I chose to incorporate it into my study and change focus to the fixture instead.   The problems and possible causes to them were identified and discussed with my tutor: The elbows fall incorrectly into or beside of the fixture.  Fixtures are old and worn down. The elbows path between conveyor and fixture are somewhat out of control The smaller dimensions have room enough to slip past the fixture. Edges to be welded are to far from each other or badly shaped Commissioning time, some start up steps is more complex then they need to be. Some of the setting possibilities in the working cell are unnecessary and can be fixed instead. The positions of pick up and welding head are not really fixed in the robot software, these are reprogrammed every time elbow size are changed. ·          Various errors at weldingo    Robot managed to pick incorrectly placed elbow   Proposals to solve the above specified problems: All parts in contact with the elbows are to be made of harden able steel. A suitable one is C45E which can be casehardened to about 700HV. On the outer edge of the conveyer a support are placed to prevent excessive wear. The fixture is partially redesigned with a support to control the elbows path better. Guide arms with dual purpose are added. First they guide the elbow into the fixture and secondly they turn it to the correct angle towards the robot. Pins are used along with quick lock clamps to obtain faster and easier commissioning. The pick and place tool developed by Outokumpu are used.
63

Examensarbete: Prefabricerad produktion med betongelement : En kostnadsutvärdering mellan prefabricerad och platsbyggd produktion / Prefabricated Production

Danielsson, Erik, Robertsson, Hans January 2008 (has links)
No description available.
64

Förbättring av utnyttjandegrad hos stansmaskin

Andersson, Christian January 2008 (has links)
Bakgrunden till examensarbetet är att det finns ett behov av att höja utnyttjandegraden i stans- och lasermaskiner hos Lars Höglund AB. Anledningen till att utnyttjandegraden behöver höjas är att företaget vill bli mera lönsamt och mera konkurrenskraftigt. Uppgiften har varit att mäta utnyttjandegraden, göra en probleminventering och ta fram förslag på åtgärder som kan lösa de problem som kom fram i probleminventeringen. Vid probleminventeringen visade det sig att det går att höja utnyttjandegraden genom att bl.a. göra en ställtidsreducering, skapa ordning och reda, samt att förebygga flaskhalsar. 5S är en metod som har använts för att ta fram förbättringsåtgärderna. Genom att följa denna metod, samt att göra några nya investeringar i företaget, ser det ut som att målet i detta arbete ska kunna uppnås.
65

BYGGBRANSCHENS EGENKONTROLLER - DERAS BETYDELSE UR ENERGISYNPUNKT / DISCRETIONARY INSPECTIONS IN CIVIL CONSTRUCTIONS - THEIR INFLUENCE ON ENERGY ASPECTS

Sjöbratt, Gustav, Thorngren, Henrik January 2009 (has links)
In order to accomplish that a construction is correctly built, it is critical to obtain a well functioning control mechanism throughout the project. The way to enable this is not by having an independent inspector constantly at your side. Today it is praxis to use check lists and have people responsible of quality to make sure that these are followed. This is where discretionary inspections play their part. These among others are documents needed to com-plete the check list. Documented discretionary inspections are based on a control mechanism that allows the entrepreneurs to, in their own organizations, self check the performed task, and by that ensure that the quality of each task is executed in a satisfying way. Due to the fact that most projects today are suffering by lack of time during construction, it is most likely to presume that the discretionary inspections can fall out of the priority, be performed in an unsatisfying way or not be performed at all. However, experience from construction business tells us that calculated energy consumption often differs from the actual, once the building is completed. This anomaly strikes hardest to apartment blocks and therefore we intend to find a connection between poorly executed dis-cretionary inspections and high energy usage. Discretionary inspections are used by most contractors in the construction business to ensure that the work in progress always serves en-vironmental lines of thoughts. During the progress in our writing we have achieved a good insight in routines and how the business works, for good and for bad. The report finishes with a discussion considering the overall concept of discretionary inspections, how to improve them and potential ways of supporting the concept in the future.
66

Den nya generationen KinBag : The new generation of KinBag

Svensson, Patrik, Klippberg, Lovisa, Jansson, Björn January 2007 (has links)
This report summarizes a Bachelor Degree Project in Integrated Product Development,carried out during the spring semester in 2007 by three students at the Product Design Engineering programme at the University of Skövde. The project was performed as an assignment for KinBag ab, a sister subsidiary to Kinnegrip ab in Lidköping, who develop,manufacture and market the golf bag KinBag, a bag with an integrated wheel carriage system. The purpose of the project was to redesign the golf bag to attract a target group consisting of golfers aged between 20 and 40. The layout of the project was as follows: The project began with a feasibility study where different problems were identified with the basis of a market research which eventually was summarized in a dynamic specification of requirements. The feasibility study was followed by a generation of ideas which contained everything from sketches to simple mock-ups with an intensive amount of thoughtful brainwork and information gathering in between. This led to the development of a number of design concepts, both on an overall level and on different parts of the golf bag. Even more detailed models were created and visualized in a three dimensional environment by means of a CAD program. The report portrays the product design process and methods utilized in the project, as well as the final result - a full-scale operational prototype of the new generation of KinBag.
67

Automation of packing process

Zia, Muhammad Irfan, Cortés Mora, Felipe January 2008 (has links)
The design work that precedes the automation of a process is not an easy job. Each one of the variables and possible risks involved in process must be carefully considered before implement the final design as well the requirements in performance and cost. However automate a dangerous, inefficient or just uncomfortable task entails many benefits that make up for the long period of design process. A well automated line will benefit the production with quality, productivity and capacity among other profits. In this project the immediate objective is to automate the “SANDFLEX Hacksaw blades” packaging process in the plant that SNAEurope owns in Lidköping. Actually the packing is completely manual. One operator packs the blades into the boxes meanwhile one more operator loads and unloads the packing station with empty and full boxes respectively. The task is both, tiring and uncomfortable for the operators as well inefficient for the company since the production rate is limited. Analyzing and observing carefully product and process, different theories and strategies to achieve the goal were developed. Three are the possible solutions to solve the problem, with different levels of automation and technologies. The robotic solution uses an articulated robot to perform all the tasks; the hybrid solution uses pneumatic devices to pack the blades and an articulated robot to support the station loading and unloading the boxes. Finally the pneumatic solution uses only pneumatic devices, which hold, open and close, push box and blades using airpower; a few sensors detect positions and states, since a PLC coordinates and controls all process. By means of discussing these solutions with the company’s engineers and workers, after a deep literature study and two test of performance, was it possible to select the most suitable solution to accomplish the packaging task. The pneumatic solution is cheap and simple, but at the same time robust and reliable. This design performs the packaging task efficiently and fast. And more important, the operator passes from pack manually the blades to monitor the process.
68

Optimering av fixtur och operationer : för effektivare produktion

Larsson, Johan January 2010 (has links)
No description available.
69

Analysis of a Production Cell using Production Simulation Tools

Hägg, David, Hofmeijer, Victor January 2010 (has links)
This final thesis was performed at Ecole Nationale Supériure D’Arts et Métiers (ENSAM) in Lille, France. The aim of the thesis has been to use two different simulation tools to analyse an existing production cell with focus on industrial engineering. The possible use and the usability of the simulation tools are also studied. The models built for simulation have been used to gather data about the cell. After analyse and discussion about the data we came to the following conclusions. The bottleneck in the cell is the Stäubli. A cheap and simple way to improve the cell is by adding new decision points (sensors) to it. The most efficient location of the new decision points is before and after the Stäubli. The production rate reaches its maximum rate for both settings with eight pallets. If the improvements are implemented then there is no reason to change the speed of the conveyor. With basic settings the speed can be increased for better productivity. The most efficient production type for short setup times is single, for both settings. Delmia is useful for visual representation. It’s also useful for measurements of time and distance since the accuracy is very high. Delmia is useful as common platform when to discuss and explain thoughts and ideas about a project. Flow simulation in Quest provides a great understanding of the production and the behaviour of the cell. It is very easy to get data in and out of the program and to compare results and impacts of changes.
70

Rutiner vid upphandling av leverantörer och underentreprenörer : En studie av Kv. Mimer 5

Lindström, Mattias January 2010 (has links)
No description available.

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