Dissertations / Theses on the topic 'Screws assembly'

The diploma thesis deals with an orientation mechanism of industrial robots for mounting of pivots and screws into the mounting holes. In the first phase there is a research of inventions mainly realized in the United States Patent and Trademark Office database. Subsequently the conditions of the assembly are solved. On the base of the conditions the functional requirements are described. The diploma thesis includes seven conceptual variants, which are proposed as a 3D design. Using the basical multi-criteria method the best conceptual variant is specified. That is specified due to the accepted criterias. In the next part of the diploma thesis there is a calculation, that comprises this technically and economically most promising conceptual variant. The calculation consists of a statics, a kinematics and a dynamics of the propel, a stenght control of the mechanism and kinematics analysis of the whole mechanism. Results of the calculation are used by the detailed design of orientation mechanism, that also comprises technological production theory and a correct assembly. Economical analysis, which comprises cost of produce of this newly developed automation equipment, is worked up in the conclusion of the diploma thesis. The diploma thesis also comprises drawings. The variant solves a new conception, which can be patented as an utility model.

The demands for an increase in productivity and reduced assembly costs require engineers to automate solutions that replace manual labor. This work concentrated on a common assembly primitive, threaded fastener insertion, in an effort to determine the nature of contact between a bolt and nut during thread mating. The assembly problem was initially simplified as a two-dimensional analysis to gain an understanding about how contacts between the bolt and nut change during counter-clockwise motion. Tessellated solid models were used during three-dimensional collision analysis in such a way that the approximate location of the contact point was enumerated. The advent of a second contact point presented a more constrained contact state since we are interested in maintaining both contacts; thus the bolt rotated about a vector defined by the initial two contact points until a third contact location was found. By analyzing the depth of intersection of the bolt into the nut as well as the vertical movement of the origin of the bolt reference frame, we determined that there are three types of contacts states present: unstable two-point, quasi-stable two-point, stable three point. Though the unstable case remains to be deciphered, the parametric equations derived in this work can be used without modification to create a full spectrum of maps at any point in the history of a threaded assembly problem. We investigated 81 potential orientations, each of which has its own set of contact points. From this exhaustive examination, we are capable of detailing a contact state history and, from this, have the potential to develop a constraint network.
Master of Science

This thesis reports upon the novel assembly and modification of screen-printed electrode systems. These key electrochemical proof-of-concepts have been benchmarked utilising voltammetric techniques, supporting the design of next-generation electrochemical sensing platforms, this thesis allows for proven laboratory-based approaches to be potentially up-scaled and commercially applied. Chapter 3 introduces the potential influence mechanical contortion upon the electrochemical performance of graphite based electroanalytical screen-printed platforms upon graphic paper, tracing paper and an ultraflexible polyester-based substrate are used. These sensors are electrochemically benchmarked against well-known redox probes hexxammineruthenium (III) chloride, potassium ferrocyanide and nicotinamide adenine dinucleotide (NADH). It was found that these ultraflexible based polyester-based electrodes are superior since they can withstand extensive mechanical contortion, yet still give rise to useful electrochemical performances. Most importantly the ultraflexible polyester electrodes do not suffer from capillary action as observed in the case of paper-based sensors causing the solution to wick-up the electrode towards the electrical connections. A new configuration is also explored using these electrode substrate supports where the working carbon electrode contains the electrocatalyst, cobalt (II) phthalocyanine (CoPC), and is benchmarked towards the electroanalytical sensing of the model analytes citric acid and hydrazine. Chapter 4 for the first time critically compares CoPC modified electrodes prepared by drop-casting CoPC nanoparticles (nano-CoPC) onto a range of carbon based electrode substrates with that of CoPC bulk modified screen-printed electrodes, towards the sensing of the model analytes L-ascorbic acid, oxygen and hydrazine. It is found that no "electrocatalysis" is observed towards L-ascorbic acid using either of these CoPC modified electrode configurations and that the bare underlying carbon electrode is the origin of the obtained voltammetric signal, which gives rise to useful electroanalytical signatures, providing new insights into literature reports where "electrocatalysis" has been reported with no clear control experiments undertaken. Chapter 5 presents a concise study upon the effect of in-situ bismuth, antimony, tin modified electrodes and combinations thereof towards the electrochemical detection of model analytes cadmium (II) and lead (II). It is found that the electrochemical response using the available range of metallic modifications is only ever observed when the underlying electrode substrate exhibits relatively slow electron transfer properties; in the case of fast electron transfer properties, no significant advantages are evident. It is demonstrated that a simple change of pH can allow the detection of the target analytes (cadmium (II) and lead (II)) at levels below that set by the World Health Organisation (WHO) using bare graphite screen-printed electrodes. Chapter 6 introduces the electroanalytical sensing of lead (II) ions utilising square-wave anodic stripping voltammetry where an increase in the electroanalytical sensitivity is observed by a factor of 5 with the screen-printed back-to-back microband configuration. Upon application of this configuration towards the quantification of lead (II) ions, within drinking water corresponds to a concentration of 2.8 (±0.3) μg/L. Independent validation was performed using ICP-OES with the levels of lead (II) ions found to correspond to 2.5 (±0.1) μg/L; the excellent agreement between the two methods validates the electroanalytical procedure for the quantification of lead (II) ions in drinking water. Finally, Chapter 7 examines for the first time, characterisation of the number of drawn pencil layers and the grade of pencil; these parameters are commonly overlooked when utilising PDEs. It is demonstrated that a PDE drawn ten times with a 6B pencil presented the most advantageous electrochemical platform, in terms of electrochemical reversibility and peak height/analytical signal. These PDEs have demonstrated beneficial electroanalytical capabilities towards p-benzoquinone and the simultaneous detection of heavy metals, namely, lead (II) and cadmium (II) all of which are explored for the first time utilising PDEs. Initially, the detection limits of this system were lower than desired for an electroanalytical platforms, however implementation of PDEs in a back-to-back configuration (as shown within Chapter 6), the detection limits for lead (II) and cadmium (II) correspond to 10 μgL-1 and 98 μgL-1 respectively within model aqueous (0.1 M HCl) solutions.

It was analyzed if instructions on a head-worn Augmented Reality display (AR-HWD) are better for manual industrial assembly tasks than instructions on a stationary screen. A prototype was built which consisted of virtual instruction screens for two example assembly tasks. In a comparison study participants performed the tasks with instructions through an AR-HWD and alternatively through a stationary screen. Questionnaires, interviews and observation notes were used to evaluate the task performances and the user experience. The study revealed that the users were excited and enjoyed trying the technology. The perceived usefulness at the current state was diverse, but the users saw a huge potential in AR-HWDs for the future. The task accuracy with instructions on the AR-HWD was equally good as with instructions on the screen. AR-HWDs are found to be a better approach than a stationary screen, but technological limitations need to be overcome and workers need to train using the new technology to make its application efficient.

The subject of this thesis is design of stand for assembly of srew-inserts into car door handles. It contains of search of possible technical solutions of part handling and available technologies of screw-insert instalation. In design part of thesis contains of analysis of construction and choice of technologies. In construction part of my thesis u can find description construction of stand and risk analysis of this machine. Moreover there are calculations, drawings of main assemblies of machine and model of stand modeled in Autodesk Inventor.

Un grand défi actuel consiste à réaliser des capteurs innovants tirant partie des propriétés singulières de nanoparticules colloïdales synthétisées par voie chimique et assemblées de manière contrôlée sur des surfaces. L’objet de cette thèse est le développement de jauges de contrainte résistives à base de nanoparticules. Ces jauges de contrainte sont constituées de lignes parallèles, de quelques micromètres de large, denses, de nanoparticules colloïdales d’or synthétisées par voie chimique et assemblées sur des substrats souples par assemblage convectif contrôlé. Le principe de ces capteurs résistifs repose sur la conduction tunnel entre les nanoparticules qui varie de manière exponentielle lorsque que l’assemblée est déformée. Des mesures électro-mécaniques couplées à des observations en microscopie électronique à balayage et à force atomique ont permis d’identifier, de quantifier et de comprendre l’impact de la taille et de la nature des ligands des nanoparticules sur la sensibilité et les phénomènes de dérive de la résistance à vide des jauges de contrainte. Ces travaux, associés à des mesures de diffusion de rayons X aux petits angles ont permis de corréler les variations macroscopiques de résistance électrique des jauges de contrainte aux déplacements relatifs des nanoparticules. Finalement, ces jauges de contrainte ultra-sensibles et miniatures, mises en matrices, ont été exploitées pour réaliser des surfaces tactiles souples multi-points et sensibles à l’intensité de l’appui
One recent big challenge is to implement innovative sensors that take advantage of the unique properties of colloidal nanoparticles chemically synthesized and assembled on various surfaces. The goal of this work is the development of nanoparticle based resistive strain gauges. These strain gauges are constructed of few micrometers wide parallel wires of close packed colloidal gold nanoparticles, chemically synthesized, and assembled on flexible substrates by convective self assembly. The principle of these resistive sensors is based on the tunnel conduction between the adjacent nanoparticles which varies exponentially as the assembly is stretched. Electro-mechanical measurements coupled with scanning electron microscopy and atomic force microscopy observations were used to identify, quantify and understand the impact of the nanoparticle size and the nature of the protecting ligands, on the gauge sensitivity and the drift of the resistance at rest of the nanoparticle based strain gauges. Coupled with small angle x-ray scattering measurements, these studies allowed us to correlate the macroscopic changes in electrical resistance of the strain gauges to the relative displacement of the nanoparticles at the nanoscale. Finally, a matrix of these miniature ultra-sensitive gauges was used to construct flexible touch screen panels capable of measuring the intensity of several touches simultaneously

The master thesis covers several issues linked to a substitution of headlamp screw fixation by a plastic nail. The thesis includes an analysis of the headlamp technology, including description of the prescribed durability tests. On the basis of the analysis some new designs of plastic nails are proposed, consistent with characteristics of plastic materials. Selected outcomes of the analysis have been tested as prototypes and verified with Finite Elements Method in SimDesigner including 3D modeling capabilities provided by the Catia V5. The feasibility study regarding a casting form of the new design of plastic nails and technical economic valuation for contingent assembly mounting is included in the thesis.

Le protéasome est une protéase multimérique essentielle et hautement conservée au cours de l’évolution. Le protéasome 26S eucaryote est l’unité catalytique du système Ubiquitine-Protéasome et contrôle de ce fait de nombreux processus cellulaires. Son dysfonctionnement participe à la pathogenèse de nombreuses maladies. Le protéasome émerge notamment comme une cible thérapeutique de choix dans le traitement de cancers. Il semble donc important d’identifier l’ensemble des processus cellulaires dans lesquels le protéasome est impliqué ainsi que l’ensemble de ses régulateurs.Mon travail de thèse a consisté à identifier et caractériser de nouveaux partenaires physiques et fonctionnels du protéasome par une approche multi-technique. Nous étudions ces facteurs dans l’organisme modèle S. cerevisiae et déterminons s’ils sont fonctionnellement conservés dans les cellules de Mammifères.Après avoir identifié des partenaires physiques et fonctionnels au moyen de cribles à grande échelle, j’ai analysé les données et établi une bibliothèque pondérée de ces partenaires. J’ai ainsi mis en évidence de nouveaux acteurs potentiellement impliqués dans le fonctionnement du protéasome. De plus, j’ai caractérisé les protéines Spg5p et Poc5p. Mes données suggèrent que Spg5p participe à la régulation du protéasome en quiescence. Poc5p, présente à la fois chez l’Homme et la levure, participe à la régulation du protéasome à au moins deux niveaux différents : elle joue un rôle de point de contrôle dans l’assemblage du complexe et un rôle inhibiteur sur son activité
The proteasome is a highly conserved essential proteolytic machine. The eukaryotic 26S proteasome is the hydrolytic heart of the ubiquitin-mediated degradation pathway and therefore controls many cellular pathways. Its dysfunction is involved in the pathogenesis of numerous diseases. Notably, the proteasome has emerged as an interesting drug target for anti-cancer therapy. It seems therefore important to identify all cellular processes in which the proteasome is involved and all of its regulators.My work was to identify and characterize new physical and functional partners of the proteasome by a multi-technical approach. We characterize these factors in the model organism S. cerevisiae and determine if they are functionally conserved in mammalian cells.After identifying physical and functional partners through large-scale screens, I analyzed the data and developed a weighted library of these partners. I have thus highlighted new actors potentially involved in the proteasome functioning. In addition, I characterized the Spg5p and Poc5p proteins. My data suggest that Spg5p participates in the regulation of proteasome during quiescence. Poc5p, presents both in human and yeast, is involved in the regulation of proteasome at at least two different levels: it acts as a checkpoint in the complex assembly and have an inhibitory effect on its activity

Hydrogen production via the electrolysis of water has gained a lot of attention in the last couple of years. Research related to electrolysers is mostly aimed towards decreasing the noble–metal catalyst content. In this study the presently used catalyst application techniques were reviewed and critically examined to find commercially applicable and effective methods. Selected methods were then practically applied to determine their feasibility and to gain “know–how” related to the practical application of these techniques. The selected techniques were the hand paint, inkjet print, screen print and spray paint techniques. Meaningful comparisons were made between the methods in terms of parameters such as practicality, waste of catalyst and microstructure. The results point out that the hand paint and spray paint methods are feasible methods although there are improvements to be made. The hand paint method was improved by applying a carbon micro porous layer to the gas diffusion layer before the painting is carried out. The addition of the carbon layer reduced the soaking of the catalyst–containing ink through the gas diffusion layer. A method not initially investigated was identified an evaluated and showed promising results in lowering the mass of catalyst applied. This method comprised of sputtering a layer of catalyst material onto a prepared gas diffusion layer. It also came to light from the results that electrodes, and therefore membrane electrode assemblies, can be produced at a much lower cost than the commercial available membrane electrode assemblies.
Thesis (M.Ing. (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2012.

Diese Dissertation befasst sich mit der industrienahen Herstellung von Katalysatorschichten für Polymer-Elektrolyt-Membran-Brennstoffzellen mit Hilfe des Tiefdrucks als Fertigungsverfahren. Um die Anforderungen an die Katalysatorschicht hinsichtlich der Schichtdicke zu erreichen, wird ein Linienraster für den Tiefdruck entwickelt. Das patentierte und verifizierte Designkonzept des Linienrasters ermöglicht es, trotz Tinten mit geringem Feststoffgehalt hohe Trockenschichtdicken zu erzeugen. Aufgrund des verwendeten Tiefdruckrasters sind Optimierungsschritte an der Fertigungsanlage notwendig, um eine hohe Schichtqualität zu erreichen. Schließlich werden kontinuierlich und industrienah Katalysatorschichten gefertigt, die als Membran-Elektroden-Einheit in einer Polymer-Elektrolyt-Membran-Brennstoffzelle erfolgreich eingesetzt werden
This work presents an industrial close manufacturing process of active electrodes for Polymer Electrolyte Fuel Cells utilizing an adapted gravure printing process. To meet the requirements of the electrodes regarding the layer thickness (weight) and quality a novel line screen with maximized dipping volume for gravure printing was developed and investigated. A design rule for this kind of screens was realized and verified by a successful manufacturing of electrodes with different dried layer thicknesses. Due to the rough structure and the high dipping volumes of these line screens an adaption and optimization of the machinery and the whole process was necessary to achieve high quality electrodes. Finally, it is shown that it is possible to manufacture continuiously in an industrial close roll-to-roll process platinum loaded electrodes, working successful as cathode in a Membran-Electrode-Assembly

碩士
國立中央大學
機械工程研究所
95
Twin screw rotor compressor has the advantages of simple structure, unique system, and reliable and easy operation; therefore it is widely used in various construction works involving aerodynamics and refrigeration air conditioning, etc., making it a new compressor model with a broad application future. This study intends to determine the three key precision parts of screw compressors by making an in-depth research into the assembly process of the twin screw rotor compressor and the size design of various parts. By utilizing and analyzing the results obtained from the 1-D and 2-D assembly simulation software developed to analyze the assembly process, possible situations and the defective rate that may occur after assembly was obtained. Modification advice was therefore proposed based on the original design and size, in order to improve the yield rate of the twin screw rotor compressor, reduce any difficulties in assembly, and cut down on both labor cost and time, while providing future designers with some reference for shortening the design period.

碩士
國立臺灣科技大學
材料科學與工程系
104
The universal popularity of industrial manipulators in a variety of industries can be observed due to the globalization of industries and the evolution of demographic structure. Following these dramatic changes, tasks, such as precision assembly, polishing and application of electronic components, which manipulators need to deal with in the future are becoming much more diversified. Position command-controlled robots in the past, therefore, can no longer achieve the tasks mentioned above. A position command-based impedance control with a assembly control strategy for implementation of screw assembly is exemplified in this thesis to present manipulators conducting precision assembly in position control mode. The use of impedance control equips the end effector on the manipulator with virtual mass, spring and damper, which enables the manipulator to complete the tasks in the unknown environments with the help of the end effector acquiring the measured data from the force/torque sensor and the contact force/torque of the exterior environments through the transformation of coordinate frame. The experiment in this thesis demonstrates how an end effector holds a screw component in the use of position command-based impedance control and screw assembly strategy to achieve the assembly task. Firstly, the necessity of the transformation of coordinate frame of the force/torque is to be proven and secondly the assembly task is to be implemented with position command-based impedance control and screw assembly strategy. Two types of screws (M8 and M6) are chosen in three separate tasks of different fastening torque to represent the abovementioned control method.

碩士
國立中正大學
機械工程系研究所
106
Monitoring of force is an important means of implementing smart manufacturing, and the installation of sensitive and robust sensors in appropriate locations for monitoring purposes is the key to smart manufacturing. Ball screw is the basic element in mechanical equipment. This research , a self-designed force sensor was installed at the relevant position in the ball screw to monitor whether the rigidity change of the ball screw during long-term use and the parallelism of the installation were appropriate, so as to demonstrate the design of the force sensor. The role and importance of the installation location at the monitoring end. The preload sensor developed by the previous research team can be successfully used to monitor the preload, but the durability and reliability of use need to be tested. To test the durability and reliability of self-developed preload sensors, an accelerated wear test was performed using a vertical shaft test platform with a small ball screw, one of the small ball screws is a low-friction, high wear-resistant coating developed by our research team. In addition to verifying the durability of the preload sensor, the benefits of the high wear-resistant coating for ball screw operation are also discussed. In the monitoring of the parallelism of the ball screw, a sensor with the same concept as the preload monitoring is used. When the preload sensors are distributed in a balanced position in the four quadrants of the screw, in addition to the monitoring of the preload, it is also possible to judge simultaneously. Changes in the degree of parallelism of the ball screw mounting. The test platform is a parallel machine that can adjust the deflection of the slave side of the linear slide. According to the results of this research, self-designed force sensors and key locations for installation can achieve monitoring of different operating conditions. From the results of accelerated wear test, it was confirmed that the durability and signal detection results measured by the preload sensor were reliable, and the low-friction high wear-resistant coating introduced could actually reduce the preload loss due to friction wear of the ball screw. According to the results of the parallelism test, it is proved that the preload sensors modified according to the requirements of different working conditions can be judged to be non-parallel by using the imbalance between the preload through installation at the key position on the screw. To detect the effect of the yaw of the work ball screw due to parallelism. This research verifies that the self-developed preload sensor can monitor preload and parallelism at the same time through appropriate adjustments, and demonstrates the preload sensor developed in this research. It is an excellent industry to design and find key locations for installation universality. Keywords: force sensor, ball screw, preload, force monitoring, parallelism

碩士
國立雲林科技大學
機械工程系碩士班
97
This research is concerned with tolerance sensitivity analysis for structure and assembly of ball screw feeding system. Building the error models and developping a logical calculation tool of machine by the geometric relations and homogeneous transformation matrix (HTM) method. Then analyze the calculated data to search the influence factors of sensitivity with different collocation conditions while the components were assembled. Afterward, the result can be applied to expect the assembly errors in advance, and then proceed to improve for designers and workers.

Thesis (M.S.)--University of Wisconsin--Madison, 1985.
Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 149-151).

碩士
國立臺灣科技大學
工業管理系
101
This study attempts to discuss the use of automatic screw driving machine to replace manpower in assembly line. The whole research process is consisted of some different steps including device selection, automatic screw driving machine structure layout and design, machine specification determination and machine approval procedure. In machine design, this study uses XYZ axes as machine main structure. The screw driver is set up on the z-axis. In manufacturing process, we design two processing models for screw supplying. One method is blowing feeder and the other is picking up device. Due to these two different models, they can be applied to different assembly processes. In testing procedure, several experiments are conducted. The testing contents include screw fasten speed, screw fasten quality, torque evaluation and finally labor cost reduction evaluation. The results indicate that machine design fits the initial expectation. This not only can reduce manpower but also improve quality and assembly efficiency. In recent years, salary increase rapidly in China. Manpower is hard to meet production requirement. It is believed that it is a good way to use automatic machine to reduce manpower and prevent manpower shortage issue in the future.

碩士
朝陽科技大學
工業工程與管理系
103
In Taiwan, small and medium enterprises take the major parts of machine tool industry. By their flexible production and adaptability, they are known for the inexpensive but exquisite customized products. They cooperate with satellite factories for the thorough processing system, taking the advantage of high assembly capacity and easy access to components. Among all the machine tools, grinding machine possesses the highest precision. It is expected to meet the crucial strict demands for final accuracy in the last step of manufacturing. It can be seen as the symbol of realizing the precision technology in machine tools. To promote the national hi-tech industry, Japan, Germany, America, Italy, and Switzerland all make their efforts to develop machine tool industry. However, based on the economic trends, the labor cost is increasing, the raw material price is raising, the production cost is reducing, and the production cycle is shortened. Under these pressures, production gradually has been developed with the aim to save more time, labor and also be automatic. Thus, it is a technical breakthrough for machinery development to infuse TRIZ theory into jigs designing. This is a new design mode that can adapt to the competitiveness in market. This project takes the assembly of screw on precise grinders as the research model, integrating the theory of TRIZ and researcher’s related personal experiences. It aims to refine the general jigs by the ways of design, jigs improvement, illustration of individual cases. Ultimately, after refining jigs, the further analyses about economic returns can be done. In this research, it is figured out that leading TRIZ into jigs designing possesses great potential, including gaining jigs’ common functions, realizing the high quality, reducing the cost, shortening the cycle, and enhancing competitiveness in markets. If it is used in assembly system, then it can improve assemblers and boost the diversity of products. Also, it is beneficial for production schedule and smooth distribution.

碩士
國立暨南國際大學
應用化學系
98
A monolayer of 2-aminoethanethiol (AET) was modified on a screen-print gold electrode through self-assembly procedure to form AuSPE-AET SAM modified electrode. The modified electrode was confirmed by atomic force microscope (AFM) and electron spectroscopy for chemical analysis (ESCA). The modified electrode was characterized by cyclic voltammetry (CV). The obtained surface coverage (ΓSAM) and double-layer capacitance (Cdl) of the AuSPE-AET SAM were 3.65×10-10 mol/cm2 and 64.38 μF/cm2, respectively. The AuSPE-AET SAM modified electrode was used for the simultaneous determination of dopamine (DA) and ascorbic acid (AA) using differential pulse voltammetry (DPV) in pH7 PBS. A linear calibration plot of AA and DA were 1-1000 μM and 2-1000 μM with the slope of 0.1603 and 0.583 μA/μM, respectively. The detection limit were 0.7 μM. The determination of AA was performed at 0.2 V in a flow injection analysis system with pH 7 PBS as a carrier solution. A linear calibration plot was obtained for 0.01-100 μM AA with the slope of 0.03719 μA/μM. The detection limit was 6.7×10-4 μM. The recovery of AA from the real sample were 94%-102.5%.

The cold chain industry has a need for a standalone, electricity independent cooling unit that is used for both storage of warehouse product and on deliveries [1]. Mixed temperature fresh and frozen food deliveries are problematic without the distributor having specialized duel compartment refrigerated trucks [2]. These trucks permanently reduce the available capacity for payload delivery [2]. It would be valuable to the cold chain industry to have a passive, independent, storage unit that can be moved using a forklift and placed anywhere within a reefer or warehouse [1]. This versatile unit is a simple mechanical system, but presents a complicated thermal problem. One of the design challenges is to thermally isolate the load from the environment and to maintain thermal conditions for a specified length of time. A proposed storage system uses heat pipes to connect the cargo compartment to a heat sink containing solid CO2. Heat pipes are a simple, passive, and quiet way to transfer heat. Heat pipe design and theory is an active area of research with numerous papers in the literature; however, there is less reported about the actual process of manufacturing. This thesis investigates a new potential application of heat pipes, with a focus on the manufacturing process and experimental performance. A total of four heat pipes and two thermosyphons are created using acetone and methanol as the working fluids, and copper and aluminum as the heat pipe housing. Performance is compared to an insulated copper tube with the same outer dimensions, where the primary performance metric is steady-state thermal resistance. In addition, transient performance is quantified as well as the temperature distribution along the outer in the evaporator, adiabatic and condenser regions. Results show that the prototypes made out of copper reached steady-state faster than the aluminum pipes, while also having a smaller temperature differential between the evaporator and condenser. Methanol and acetone have similar performance over the temperature ranges of 198 K to 358 K. The best performing prototype is a copper thermosyphon containing methanol which achieves an effective thermal resistance of 2.0 K/W with an applied load of 40.7 W, when the condenser is cooled with dry ice in acetone. When cooled with ice water the copper thermosyphon achieves an effective thermal resistance of 0.5 K/W with a load of 40.7 W.
Graduate
0548
jstrain@uvic.ca

Diese Dissertation befasst sich mit der industrienahen Herstellung von Katalysatorschichten für Polymer-Elektrolyt-Membran-Brennstoffzellen mit Hilfe des Tiefdrucks als Fertigungsverfahren. Um die Anforderungen an die Katalysatorschicht hinsichtlich der Schichtdicke zu erreichen, wird ein Linienraster für den Tiefdruck entwickelt. Das patentierte und verifizierte Designkonzept des Linienrasters ermöglicht es, trotz Tinten mit geringem Feststoffgehalt hohe Trockenschichtdicken zu erzeugen. Aufgrund des verwendeten Tiefdruckrasters sind Optimierungsschritte an der Fertigungsanlage notwendig, um eine hohe Schichtqualität zu erreichen. Schließlich werden kontinuierlich und industrienah Katalysatorschichten gefertigt, die als Membran-Elektroden-Einheit in einer Polymer-Elektrolyt-Membran-Brennstoffzelle erfolgreich eingesetzt werden.
This work presents an industrial close manufacturing process of active electrodes for Polymer Electrolyte Fuel Cells utilizing an adapted gravure printing process. To meet the requirements of the electrodes regarding the layer thickness (weight) and quality a novel line screen with maximized dipping volume for gravure printing was developed and investigated. A design rule for this kind of screens was realized and verified by a successful manufacturing of electrodes with different dried layer thicknesses. Due to the rough structure and the high dipping volumes of these line screens an adaption and optimization of the machinery and the whole process was necessary to achieve high quality electrodes. Finally, it is shown that it is possible to manufacture continuiously in an industrial close roll-to-roll process platinum loaded electrodes, working successful as cathode in a Membran-Electrode-Assembly.