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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.
81

Návrh technologie výroby tělesa světlometu motocyklu / Design of manufacturing technology for motorcycle headlamp body

Nosek, Jan January 2010 (has links)
The thesis is a proposal technology of the main body of motorcycle polymer material from Bayer's APEC - high temperature polycarbonate 1703. Literary study summarizes findings from a thermoplastic injection molding technology and the possibilities of structural design of injection molds, plastic plating technology from a focus on the most important technology in the field of lighting technology vehicles. Given the anticipated production run of 50 thousand. pieces are assessed a total of 2 variants of the molding parts. The practical part was modeled and specified product designed mold. Construction was done by using SolidWorks 2007 software and normalities FCPK Bytów and HASCO. For the selected option is implemented technological calculations. For the proposed technology was chosen Allrounder injection molding machine 570 A the manufacturer Arburg designed and suitable technological process of production.
82

On the Compensation of Dynamic Reaction Forces in Stationary Machinery

Radermacher, Tobias, Lübbert, Jan, Weber, Jürgen January 2016 (has links)
This paper studies a method for active electrohydraulic force compensation in industrial scale high power applications. A valve controlled cylinder moves a mass using the force of inertia to compensate for the reaction forces of an industrial process. Two strategies for force compensation are developed and investigated in a 160 ton clamping unit of an injection moulding machine to significantly reduce the excitation. Results of the different strategies are shown and evaluated. Advantages and drawbacks of the developed electrohydraulic force compensation are discussed.
83

Prozessintegrierter Transfer von Nanopartikeln auf Polycarbonatoberflächen beim Spritzgießen

Kroschwald, Felix 01 December 2015 (has links)
Im Rahmen dieser Arbeit werden die Nanopartikel mittels verschiedener Beschichtungsverfahren auf eine Zwischenoberfläche (Substrat) appliziert. Diese wird anschließend in die Kavität einer Spritzgießmaschine eingelegt, wobei es während des Spritzgießprozesses zur Übertragung der Nanopartikel auf das PC-Formteil kommt. Als Modellsystem werden dafür Goldnanopartikel (AuNP) verwendet, da diese charakteristische optische, chemische und physikalische Eigenschaften aufweisen. Im weiteren Verlauf wurde die Übertragung von Kohlenstoffnanoröhren (CNT) und Siliziumdioxidnanopartikeln (SiO2-NP) untersucht. Die Oberflächen der SiO2-NP wurden außerdem mithilfe funktioneller Alkoxysilane modifiziert, um den Einfluss der Nanopartikeloberfläche auf die Übertragung zu untersuchen.
84

Manufacturing of Electric Candle Preparing Industrial Production / Tillverkning av elektriskt stearinljus förberedelse för industriell produktion

Hamngren, Leonard January 2018 (has links)
Det här examensarbetet är en fortsättning på ett tidigare kandidatexamensarbete vars syfte var att bestämma form och funktion för ett elektriskt stearinljus som skulle se så verklighetstroget ut som möjligt. En prototyp av ljuset byggdes för att testa den nya tekniska lösningen. Syftet med föreliggande examensarbetet var att undersöka hur ljuset skulle kunna tillverkas industriellt. Vad som var optimal tillverkningsteknik och bästa material för varje komponent undersöktes. Svårigheten var att fatta välgrundade beslut för hur vissa komponenter skulle tillverkas, varför det krävdes fysiska experiment för detta. Ett exempel på en sådan komponent var ljusets låga vars uppgift är att sprida ljus, jämt i alla riktningar. Lågan behöver därför ha en skrovlig yta som kan sprida ljus. För att kunna tillverka lågan krävdes en teknik som gör det möjligt att producera dess komplicerade form tidseffektivt. Först bestämdes därför att lågan skulle formsprutas då det är är en teknik som möjliggör gjutning av avancerade former som går på kort tid. Det bestämdes även att lågan skulle göras i akrylplast då det är en plast med hög transparens. För att bestämma hur den skrovliga ytan skulle åstadkommas utfördes sedan ett experiment där olika gjutformar tillverkades. Dessa gjutformar ytbearbetades på olika sätt med bl.a. blästring, gnistbehandling, etsning och gravering. Genomskinlig plast användes för att formspruta i gjutformarna. Det resulterade i formsprutade plastbrickor med olika ytstrukturer. Dessa ytor belystes och dess ljusspridande förmåga mättes med två olika mättekniker. Det visade sig att den etsade ytan spred ljus bäst. Jämfört med ytan som fanns på prototypens låga så visade mätningar att den etsade ytan var något bättre på att sprida ljus. Även andra experiment gjordes för val av en fjäderkomponent och val av limmetod.Ytjämnhetsmätning av den etsade ytan visade att ytjämnheten var Ra 18 µm och på grund av skrovligheten i ytan kunde lågan inte gjutas i ett stycke utan fick delas upp i två halvor. En CAD-modell av ett formverktyg som gjuter en halv låga konstruerades med tillräckliga släppvinklar.  Tack vare den etsade ytans goda ljusspridande förmåga behövde ljusets ljuskälla inte lysa starkare än 30 lumen vilket innebär att LED-lampans effekt inte behöver vara större än 0,5 W. De två AA batterier som strömförsörjer ljuset skulle då räcka i minst 15 timmar. / This master thesis is a continuation of an earlier bachelor projectwhere the purpos was to develop form and function for an electric candle that would look as realistic as possible. A prototype of the light was made to test the technical solution. The purpose of this master thesis was to find out how this candle should be manufactured in industry. Optimal manufacturing process and material were assigned to all the components. For some components it was harder to make well grounded decitions about the manufacturing process which is why physical experiments were needed. One of such components is the flame who’s function is to spread light even in all directions. Therefor the flame needs a rough surface that can scatter light. In order to manufacture the flame it required a manufacturing process that could make the complex form on short time. Acrylic plastic was choosen as the material for the flame due to its high light transmittance. To determine how the surface on the flame would be created an experiment was conducted were a couple of mold forms were made. The surface of the forms was processed with blasting, electrical discharge machining, etching and scraping. Transparent plastic was injection molded in these forms. That resulted in pieces of plastic with different surfaces. These pieces were lit and the light scattering properties were measured in two different ways. It showed that the etched surface scattered most light. Other experiments concerning spring testing and glue testing were made. The surface roughness were measured. The etched surface had a surface roughness of Ra 18 µm and because of the high roughness the flame could not be molded in one piece but was split in two. A CAD-model of a mould that makes a half flame was constructed with required draft angles. Thanks to the good light scattering of the etched surface, the lightsource did not need to be stronger than 30 lumen which meen the power of LED-light only had to be around 0,5 W. That meant that two AA batteries could power the light for 15 hours.
85

Validation of the modified rule of mixtures using a combination of fibre orientation and fibre length measurements

Hine, P., Parveen, Bushra, Brands, D., Caton-Rose, Philip D. 04 May 2014 (has links)
No / The goal of this study was to investigate the fibre orientation distribution (FOD), and subsequent mechanical properties, of an injection moulded plate with two different number averaged fibre lengths, termed in this paper medium (1.35 mm) and long (2.40 mm). Fibre orientation measurements (FOD) were made using the 2D elliptical section method and an in-house developed image analyser. The samples were injected from a pin gate located at the centre and top of the plate. Expansion flow on the divergent flow front from this pin gate resulted in a core region with circumferential alignment, while through thickness shear resulted in the usual realignment of fibres in the flow direction either side of the core, termed the shell layers. Two interesting aspects were discovered from these measurements. First, and most importantly, the FOD was found to be independent of the two fibre lengths in this study, and so predominantly controlled by the mould shape and the interaction with the flow front. Second, the fibres in the core region were found to be much closer packed than those in the shell regions. The interaction between the flow front and the mould shape resulted in a range of FOD across the moulded plate, from equal in-plane orientation at the centre of the plate, to highly aligned at the plate edge. This gave a very useful set of samples from which to test out the well known modified rule of mixtures (MROM). Often the fibre orientation distribution cannot be measured directly, but indirectly using the modified rule of mixtures model in reverse. The samples from this moulding (at two different average fibre lengths) gave an excellent opportunity to validate this often used approach. Both the tensile modulus and strength (measured parallel to the injection direction) were found to show a strong correlation with the measured fibre orientation, with a significant increase in both measures between the centre and the edge of both plates. The increased length of the ‘long’ fibre plate was found to give only a small increase in tensile modulus but a much larger increase in tensile strength. The tensile modulus showed a linear dependence with the measured fourth order orientation tensor average, 〈cos4 θ〉, with respect to the injection direction of the plate, as predicted by the modified rule of mixtures. Excellent agreement was found between the measured modulus and the predictions from the modified rule of mixtures, based only on measured quantities (matrix modulus, fibre fraction and average fibre length) for both plates.
86

Multi-scale modelling describing thermal behaviour of polymeric materials. Scalable lattice-Boltzmann models based upon the theory of Grmela towards refined thermal performance prediction of polymeric materials at micro and nano scales.

Clark, Peter G. January 2012 (has links)
Micrometer injection moulding is a type of moulding in which moulds have geometrical design features on a micrometer scale that must be transferred to the geometry of the produced part. The difficulties encountered due to very high shear and rapid heat transfer of these systems has motivated this investigation into the fundamental mathematics behind polymer heat transfer and associated processes. The aim is to derive models for polymer dynamics, especially heat dynamics, that are considerably less approximate than the ones used at present, and to translate this into simulation and optimisation algorithms and strategies, Thereby allowing for greater control of the various polymer processing methods at micrometer scales.
87

Fibre Orientation and Breakage in Glass Fibre Reinforced Polymer Composite Systems: Experimental Validation of Models for Injection Mouldings. Validation of Short and Long Fibre Prediction Models within Autodesk Simulation Moldflow Insight 2014

Parveen, Bushra January 2014 (has links)
End-gated and centre gated mouldings have been assessed with varying thickness and sprue geometries for the centre gate. Alternative image analysis techniques are used to measure the orientation and length of injection moulded short and long fibres composite components. The fibre orientation distribution (FOD) measurements for both geometries have been taken along the flow path. In shear flow the FOD changes along the flow path, however the FOD remains relatively constant during expansion flow. The core width and FOD at the skin within a long glass fibre (LGF) specimen is different in comparison to a short glass fibre (SGF) specimen. Fibre length measurements have been taken from the extrudate, sprue and 2 positions within the centre gate cavity. The size of the sprue has little influence on fibre breakage if the moulding is more than 1 mm thick The SGF FOD prediction models within Autodesk Simulation Moldflow Insight 2014 (ASMI) have been validated against measured SGF data. At present, by default, the models over-predict the <cos2θ> for most geometries. When the coefficients are tailored for each model, drastic improvements are seen in the FOD prediction. The recently developed SGF RSC model accurately predicts the FOD in shear, in a thin geometry, whereas the Folgar-Tucker model predicts the FOD accurately in expansion flow. The measured LGF fibre length distribution (FLD) and FOD have been validated against the LGF prediction models. The LGF models are currently under predicting the breakage and over-predicting <cos2θ>. The breakage prediction improves if measured FLD of the extrudate is input into the model. / Autodesk Ltd.
88

Process Fingerprinting of Microneedle Manufacturing Using Conventional and Ultrasonic Micro-injection Moulding

Gulcur, Mert January 2019 (has links)
This research work investigates the development and application of process fingerprinting for conventional micro-injection moulding and ultrasonic micro injection moulding manufacturing of microneedle arrays for drug delivery. The process fingerprinting method covers in-depth analysis, interrogation and selection of certain process data features and correlation of these features with product fingerprints which are defined by the geometrical outcomes of the microneedle arrays in micro scale. The method was developed using the data collected using extensive sensor technologies attached to the conventional and ultrasonic micromoulding machines. Moreover, a machine vision based microneedle product evaluation apparatus is presented. Micromachining capabilities of different processes is also assessed and presented where state-of-the-art laser machining was used for microneedle tool manufacturing in the work. By using process fingerprinting procedures, conventional and ultrasonic micromoulding processes has been characterised thoroughly and aspects of the process that is affecting the part quality was also addressed for microneedle manufacturing. It was found that polymer structure is of paramount importance in obtaining sufficient microneedle replication. An amorphous polymer have been found to be more suitable for conventional moulding whereas semi-crystalline materials performed better in ultrasonic micromoulding. In-line captured micromoulding process data for conventional and ultrasonic moulding provided detailed insight of machine dynamics and understanding. Linear correlations between process fingerprints and micro replication efficiency of the microneedles have been presented for both micromoulding technologies. The in-line process monitoring and product quality evaluation procedures presented in this work for micro-injection moulding techniques will pave ways for zero-defect micromanufacturing of miniature products towards Industry 4.0.
89

A new process chain for producing bulk metallic glass replication masters with micro- and nano-scale features

Vella, P.C., Dimov, S.S., Brousseau, E., Tuinea-Bobe, Cristina-Luminita, Grant, C., Whiteside, Benjamin R. 02 May 2019 (has links)
No / A novel process chain for serial production of polymer-based devices incorporating both micro- and nano-scale features is proposed. The process chain is enabled by the use of Zr-based bulk metallic glasses (BMG) to achieve the necessary level of compatibility and complementarity between its component technologies. It integrates two different technologies, namely laser ablation and focused ion beam (FIB) milling for micro-structuring and sub-micron patterning, respectively, thus to fabricate inserts incorporating different length scale functional features. Two alternative laser sources, namely nano-second (NS) and pico-second (PS) lasers, were considered as potential candidates for the first step in this master-making process chain. The capabilities of the component technologies together with some issues associated with their integration were studied. To validate the replication performance of the produced masters, a Zr-based BMG insert was used to produce a small batch of micro-fluidic devices by micro-injection moulding. Furthermore, an experimental study was also carried out to determine whether it would be possible by NS laser ablation to structure the Zr-based BMG workpieces with a high surface integrity whilst retaining the BMG’s non-crystalline morphology. Collectively, it was demonstrated that the proposed process chain could be a viable fabrication route for mass production of polymer devices incorporating different length scale features.
90

Technologie výroby plastového krytu mobilního telefonu / Production technology of mobile phone plastic cover

Heralt, Aleš January 2009 (has links)
The master´s thesis is focused on technology of injection plastics. The specified part is guard cover of mobile phone. The first part of thesis is focused on description of technology with priority on construction of form. The second part of thesis includes calculations of parameters, which are needed for production, along with techno-economic evaluation of selected construction design.

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