Dissertations / Theses on the topic 'Float glass forming process'

In the electron gun assembling process, metals grids are inserted into preheated glass. The 2D numerical model proposed in this work takes into account most of the thermo-mechanical phenomena. It allows computing the thermal gradients in the glass, its flows around the metal claws, and the residual stresses in both components. A Maxwell model is used for the description of the visco-elastic behaviour of glass. A nodal master/slave algorithm for both mechanical sliding and heat transfer at the glass/metal interface is proposed, so providing a direct resolution of the coupled problem. The identification of the unknown material and interface properties is first studied in simplified experiences of ID heat transfer and by photo-elastic observations of a glass/metal sample. Next, these properties, as well as the unknown boundary conditions of the process are identified by inverse analyses, using experimental data obtained on a pilot line. The interpretation of the residual stresses predicted by our model and its sensitivity to the parameters allows describing the mechanisms of anchoring. The importance of the thermal cycle of both components as well as the metal and geometry of the claws is clearly shown. This allows suggesting technological improvements of the anchoring in electron guns and of the production process
La fabrication des canons éléctroniques consiste à indenter des grilles métalliques dans du verre préalablement chauffé. Le modèle numérique en 2d que nous proposons dans ce travail prend en compte les phénomènes thermo-mécaniques qui mènent à l'établissement d'un gradient de température dans le verre, son écoulement autour de la griffe métallique ainsi qu'au développement des contraintes résiduelles dans le verre et dans le métal. Pour le comportement visco-élastique du verre, une loi de Maxwell a été choisie. Le contact est géré par un algorithme de type maître/esclave, exprimé aux noeuds de l'interface verre/métal, tant pour le frottement mécanique que pour le transfert thermique. Les propriétes inconnues des matériaux et de l'interface sont d'abord étudiées dans des expériences de transfert thermique 1d et de photo-élasticimétrie sur un assemblage simplifié verre/métal. Ensuite, celles-ci, ainsi que les conditions aux limites inconnues du procédé, ont été identifiées par analyses inverses avec des mesures expérimentales sur la ligne pilote. Les contraintes résiduelles prévues par notre modèle et leur sensibilité aux paramètres nous a permis de décrire les mécanismes d'ancrage. L'importance des cycles thermiques, du choix du métal et de la géometrie des griffes sont mis en évidence. Cela nous permet de proposer des améliorations technologiques du procédé de fabrication et de la qualité de l'ancrage des canons a électrons

Thesis (S.M. and S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1999.
Includes bibliographical references (p. 93).
The design of fiberglass manufacturing setups has evolved largely by trial and error. Efforts are now in place to achieve a better understanding of the fiber forming process. To facilitate this research, a smaller and simpler version of the full-scale fiber forming process is being used. This system has vastly different geometry and produces a small number of fibers. Work in this project has concerned optimization of the small-scale process to more closely match the behavior to production line fiberglass forming positions, such that results of experiments on the smaller system are applicable to the full scale system. Efforts were also put into simplification of the system, such that process variables can more easily be isolated for further study. The primary effort of this project was put into controlling glass head pressure. On the full-scale system constant glass depth is maintained and the glass weight controls the flow rate of glass through the fiber forming tips. On the small system flow rate is controlled by a combination of changing glass weight and added air pressure. The pressure control system developed in this project uses glass resistance to measure glass depth and outputs a signal to a solenoid valve to add the appropriate amount of air pressure above the glass. The glass resistance measuring system had to be calibrated for a range of temperatures. Resistance data was collected while mass flow of glass was monitored. From the mass flow glass depth was calculated to an accuracy of 3%. When set to simulate the full-scale fiberglass forming operation the pressure control valve can control pressure to within 4.5% of 5.5 kPa required pressure. A new fiber winding system was designed and implemented. This system assures even distribution of fibers along the axis of a winder drum, speed control to within 1%, and limited vibration transmission to the fibers while they are in the forming and cooling regions. The pressure control and winder control systems were incorporated into the same LabView interface to assure ease of use. From the interface an operator can set winder speed and total head pressure and monitor the control of both to assure that the system is behaving appropriately.
by Christa R. Ansbergs.
S.M.and S.B.

El disseny del motlle preparador és un punt crític en el desenvolupament de nous flascons ja que defineix la distribució d’espessors de vidre en les ampolles fabricades. Tot i això, el disseny d’aquestes cavitats encara es basa en el coneixement empíric i la metodologia d’assaig i error. Per aquestes raons, diverses proves de fabricació poden ser necessàries, les quals impliquen temps no productius i allarguen el temps de desenvolupament. Ramon Clemente és un fabricant de flascons de vidre que vol escurçar el buit actual entre l’experiència dels vidriers i el coneixement científic de les simulacions numèriques. L’objectiu és implementar un model que descrigui numèricament el comportament termomecànic del vidre en el procés de fabricació per bufat-bufat per predir la distribució d’espessors en els flascons. Així doncs, aquesta tesi es centra en un estudi numèric i experimental de la producció d’ampolles de vidre. Emprant una càmera termogràfica es van realitzar anàlisis tèrmiques sota condicions reals de fabricació. Aquestes inclogueren mesures experimentals de la gota de vidre, parison i flascons acabats en tot el procés productiu. A més, les operacions de conformat i les propietats del vidre definiren un marc teòric per modelar numèricament el procés de bufat-bufat amb ANSYS Polyflow. Posteriorment, es varen implementar dos models numèrics. Primer, un assaig de caiguda de la gota proporcionà una descripció del flux de vidre al llarg del temps per validar la caracterització de la viscositat i el flux no isotèrmic i newtonià previst per les simulacions. Desprès, un model numèric del procés de bufat-bufat per predir el repartiment d’espessors de vidre en els envasos fabricats. Els resultats numèrics es van correlacionar amb temperatures experimentals del vidre i amb els gruixos dels flascons tallats. Els resultats obtinguts permeten tenir una millor comprensió del comportament termomecànic del vidre dins de les cavitats dels motlles. A més, les simulacions predigueren correctament la distribució d’espessors al final del procés, en funció del disseny del motlle preparador i de les condicions de fabricació, tant en el model axisimètric com tridimensional. La validació del model numèric en tres dimensions és molt important per a Ramon Clemente, ja que obre la porta a predir numèricament els gruixos de flascons amb geometries complexes en lloc de limitar-se a ampolles axisimètriques. Per tant, permetent desenvolupar nous flascons de vidre pel sector de la perfumeria de forma més ràpida i de millor qualitat.
El diseño del molde preparador es un punto crítico en el desarrollo de nuevos frascos ya que define la distribución de espesores de vidrio en las botellas fabricadas. Todo y eso, el diseño de estas cavidades aún se basa en el conocimiento empírico y la metodología de ensayo y error. Por estas razones, pueden ser necesarias varias pruebas de fabricación, las cuales implican tiempo no productivo y alargan el tiempo de desarrollo. Ramon Clemente es un fabricante de frascos de vidrio que quiere reducir el vacio actual entre la experiencia de los vidrieros y el conocimiento científico de las simulaciones numéricas. El objetivo es implementar un modelo que describa numéricamente el comportamiento termo-mecánico del vidrio en el proceso de fabricación por soplado-soplado para predecir la distribución de grosores en los frascos. Así pues, esta tesis se centra en un estudio numérico y experimental de la producción de botellas de vidrio. Usando una cámara termográfica se realizaron análisis térmicos bajo condiciones reales de fabricación. Éstas incluyeron medidas experimentales de la gota de vidrio, parison y frascos acabados durante el proceso productivo. Además, las operaciones de conformado y las propiedades del vidrio definieron un marco teórico para modelar numéricamente el proceso de soplado-soplado con ANSYS Polyflow. Posteriormente, se implementaron dos modelos numéricos. Primero, un ensayo de caída de la gota proporcionó una descripción del flujo de vidrio a lo largo del tiempo para validar la caracterización de la viscosidad y el flujo no isotérmico y newtoniano previsto por las simulaciones. Después, un modelo numérico del proceso de soplado-soplado para predecir el reparto de espesores de vidrio en los envases fabricados. Los resultados numéricos se correlacionaron con temperaturas experimentales del vidrio y con los grosores de los frascos cortados. Los resultados obtenidos permiten tener una mejor comprensión del comportamiento termo-mecánico del vidrio dentro de las cavidades de los moldes. Además, las simulaciones predijeron correctamente la distribución de espesores al final del proceso, en función del diseño del molde preparador y de las condiciones de fabricación, tanto en el modelo axisimétrico cómo tridimensional. La validación del modelo numérico en tres dimensiones es muy importante para Ramon Clemente, ya que abre las puertas a predecir numéricamente los grosores de los frascos con geometrías complejas en lugar de limitarse a botellas axisimétricas. Por lo tanto, permitiendo desarrollar nuevos frascos de vidrio para el sector de la perfumería de forma más rápida y de mejor calidad.
The design of the blank mold cavity is a critical step in the development of new perfume containers as it defines the glass thickness distribution of the manufactured bottles. Despite that, mold cavity design is still based on empirical knowledge and trial and error. Hence, several manufacturing tests may be required, which increase time to market and involve significant downtimes. Ramon Clemente is a glass manufacturing company that wants to bridge the gap between industrial experience in glassmaking and scientific and engineering knowledge present in numerical simulations. The goal is to implement a numerical model to describe the thermo-mechanical behavior of glass during the blow and blow forming process and predict the glass thickness distribution of the manufactured bottles. Therefore, this thesis focuses on a numerical and experimental study of the production of glass perfume containers. Then, thermal analyses were performed using an infrared thermal camera under industrial manufacturing conditions. These included experimental measurements of the glass gob, parison and final container throughout the forming process. In addition, forming operations and glass properties defined a framework to numerically model the blow and blow forming process using ANSYS Polyflow. Subsequently, two numerical models were implemented. First, a gob drop test to provide a description of the glass flow over time to validate the characterized viscosity and the Newtonian non-isothermal flow predicted by the simulations. Later, a numerical model of the blow and blow forming process to predict the glass thickness distribution of the manufactured containers. Numerical results were correlated with experimental glass temperatures and thickness distributions of sectioned containers. Results lead to gain a better understanding of the thermo-mechanical behavior of glass inside the mold cavities. Moreover, simulations successfully predicted the thickness distribution after the container forming process, showing the influence of the blank mold cavity and process conditions in both axisymmetric and three-dimensional models. Validation of the 3D model has strong implications for Ramon Clemente, as it paves the way for numerically predicting the glass thicknesses of complex perfume containers instead of being limited to axisymmetric bottles. Therefore, allowing to develop new glass containers faster and of better quality.

Single molecule studies using nanopores have gained attention due to the ability to sense single molecules in aqueous solution without the need to label them. In this study, short DNA molecules and proteins were detected with glass nanopores, whose sensitivity was enhanced by electron reshaping which decreased the nanopore diameter and created geometries with a reduced sensing length. Further, proteins having molecular weights (MW) ranging from 12 kDa to 480 kDa were detected, which showed that their corresponding current peak amplitude changes according to their MW. In the case of the 12 kDa ComEA protein, its DNA-binding properties to an 800 bp long DNA molecule was investigated. Moreover, the influence of the pH on the charge of the protein was demonstrated by showing a change in the translocation direction. This work emphasizes the wide spectrum of detectable molecules using nanopores from glass nanocapillaries, which stand out because of their inexpensive, lithography-free, and rapid manufacturing process

Pour prévoir et mettre au point la mise en forme d'objets en verre à partir de feuilles plates, les simulations numériques par éléments finis sont développées pour deux grands procédés, le Press-bend et le Blow-bend. Ces deux procédés, utilisés actuellement par les fabricants verriers, comportent deux phases essentielles: le pressage et le fluage pour le premier, le soufflage et le fluage pour le second. Ces modes de production nécessitent la maitrise d'un nombre important de paramètres. Les délais de conception et la minimisation des couts de revient limitent le nombre de mises au point expérimentales. C'est à ce niveau que les simulations numériques en tant qu'outil d'étude de faisabilité et d'optimisation, joue un rôle déterminant. Celles-ci sont associées à une stratégie originale intégrant la conception assistée par ordinateur pour décrire les entités géométriques et surfaciques, et à la métrologie afin de vérifier les critères dimensionnelles. A partir des prescriptions initiales du concepteur, la confrontation des résultats numériques et des relevés expérimentaux pour quatre volumes formes par Press-bend et Blow-bend permettent la validation des paramètres process utilisés. Finalement, une méthode inverse est mise en œuvre afin d'optimiser, dans un premier temps, la carte de températures dans le volume avant formage puis, la topologie des outils de mise en forme.

We study physical systems composed of at least two immiscible fluids occu- pying different regions of space, the so-called phases. Flows of such multi-phase fluids are frequently met in industrial applications which rises the need for their numerical simulations. In particular, the research conducted herein is motivated by the need to model the float glass forming process. The systems of interest are in the present contribution mathematically described in the framework of the so-called diffuse interface models. The thesis consists of two parts. In the modelling part, we first derive standard diffuse interface models and their generalized variants based on the concept of multi-component continuous medium and its careful thermodynamic analysis. We provide a critical assessment of assumptions that lead to different models for a given system. Our newly formulated class of generalized models of Cahn-Hilliard-Navier-Stokes-Fourier (CHNSF) type is applicable in a non-isothermal setting. Each model belonging to that class describes a mixture of separable, heat conducting Newtonian fluids that are either compressible or incompressible. The models capture capillary and thermal effects in thin interfacial regions where the fluids actually mix. In the computational part, we focus on the development of an efficient and robust...

碩士
國立聯合大學
材料科學工程學系碩士班
105
The float process is one of the most widely employed procedures for flat glass manufacture. It can produce flat glass in a continuous ribbon form. The float glass naturally exhibits high planarity without the need for polishing. In the process, the tin bath is the crucial stage for forming glass. The transport phenomena of molten glass flowing from spout lip tile into tin bath will affect the quality of float glass. Notably, the wetback flow, meaning that the molten glass flows backwards and touches the wetback tile, play an important role. It shows that how the wetback flow is directed will determine the utilizable area and defects of float glass. In this work, a model for the front end of the tin bath is established. Because three-phase fluids (e.g., molten glass, molten tin and atmosphere gas) coexist in the tin bath, we use the multiphase model in Fluent software to simulate and analyze the transport phenomenon. This model is constructed based on literature reports. Besides, massless particles are dropped into the fluid to trace the flow path, known as streamline. Moreover, the distribution of stress on restrictor tile is discussed. When the local stress is too large, the restrictor tile may suffer erosion and therefore reduce its lifespan. According to simulation results, when the length of wetback tile increases, the space for guiding the wetback flow becomes large, leading to an increase of mass flow of molten glass. Analogously, increase of angle of restrictor tile can also promote the mass flow. In addition, the stress distribution on the restrictor tile decreases with the large guiding space, where the maximum stress is reduced and the stress distribution is more even. Nevertheless, a large guiding space will cause the energy loss of wetback flow, resulting in a dead zone at the corner between wetback tile and restrictor tile. This work demonstrates that in the 157-135 case, a better guidance for wetback flow can be achieved, and no dead zone appears at the corner.

碩士
雲林科技大學
工業工程與管理研究所碩士班
97
Due to the competitive market today in the glass fiber yarn industry, high-end product with reliable quality seems to be the best strategy to develop the competitiveness for a company’s future. This research wants to investigate the factors of D450 yarn fiber forming process, which affect the fuzz index and throughput. The objective is to minimize the fuzz index and maximize throughput. Since the model has six factors and two levels each, we want to identify the factors that have large effect. By doing this, 26-2 fractional factorial design is demonstrated and double replication is used in this screening experiment. This design can quickly and efficiently identify the subset of factors that are significant. After screening experiment, four factors are significant. This research apply Response Surface Method with Central Composite Design to find out the optimize parameters at second step. The results from the experiments suggest that four out of six factors were significant, which are winding speed, applicator speed, winding ratio and G setting. In additions, the validity of the model was performed based on the regression models to verify the response. The model was verified using the confirmation runs and the predicted values were very close to the actual values and thus supporting the design. Based on the results, this research recommend that both for maximum throughput and acceptable fuzz index, 3785 RPM winding speed, 19M/Min. for applicator , 3.07 winding ratio and G setting at 30.79mm would be the best combination for fiber forming parameters. Key words：Glass fiber yarn, Design of Experiment, Response Surface Method, Central Composite Design, Fractional Factorial Design

碩士
中華大學
機械工程學系碩士班
97
Arrayed glass micro-lenses have numerous applications in the field of opto-electronics. Traditional precision glass molding process is too expensive and molding for arrayed glass lenses is difficult to avoid glass sticking and gas bubbles trapped into glass material. This study developed a new process to produce an arrayed glass micro-lenses by gas pressure assisted forming process, which is considered to have a great potential for the mass production of arrayed glass lenses with low cost, ease of manufacture and free of surface defects. Pyrex glass plates with transition temperature (Tg) of 560℃ were used in this study. The WC/Co and stainless steel plates with arrayed through holes were employed as the molds. Glass plate was put on the mold and N2 was introduced into the closed chamber to allow gas pressure up to 3kg/cm2. IR heating allows the glass plate to approach the soft point, and the glass was forced flowing into the arrayed through holes to form the arrayed glass lenses due to viscoelastic deformation. The surface profile of molded glass lenses can be well manipulated by controlling the molding conditions including temperature, gas pressure and duration. At the same molding conditions, the molds with bigger through holes favor the arrayed glass lenses with a higher peak height compared to that of smaller through-hole molds. To use WC/Co as the mold material is beneficial to the mold release and the molded lenses with a higher peak height compared to that of stainless mold. Key words: gas assisted glass molding, arrayed lenses, through-holes mold

碩士
中華大學
機械與航太工程研究所
94
There are several approaches to fabricate arrayed glass microlens such as sol-gel, ultra-precision machining and molding process. The glass molding process is considered to have a great potential for the mass production of arrayed glass microlens with high precision and lower cost. However, the glass molding has a serious problem of mold sticking with glass which needs to be resolved. An innovated vacuum forming process to fabricate arrayed glass micro-lens was developed in this study. The SiC plate with arrayed through holes was employed as a mold. Glass plate was put on the SiC mold connected with a steel pipe on the backside to allow pumping gas and achieve pressure difference between front and back side of the glass plate. The furnace temperature was increased to achieve glass soft point so as to allow the glass plate to be sucked and flows into the arrayed through holes and to form the arrayed micro-lens. A higher working temperature and duration tends to produce the lens array with a smaller curvature. However, severe sticking between the glass and WC mold was observed. Cooling rate has to be controlled to avoid cracking of the glass due to the thermal stress problem.

碩士
中華大學
機械工程學系碩士班
99
Currently, Fresnel lens is widely used in electromechanical products and daily necessities, such as lighthouse lighting, screens, projector, light, camera, CD-ROM drive, magnifying glass, glasses, alarm and concentrated solar power systems. The material used for manufacturing Fresnel lens nowadays is either PC or PMMA plastic; however, it is unable to withstand high temperature and vulnerable to ultraviolet radiation degradation. It also easily causes scratch defect it is essential to on the surface and results in low performance after long term usage. Hence, develop low-cost glass Fresnel lenses to replace current available plastic material. In this study, optical analysis of Fresnel micro-structure was carried out by FRED software and a mold of Fresnel lens then was produced by using stainless steel. After that, glass lens (SCHOTT B270) with diameter of 30 mm was fabricated by gas pressure assisted forming process using stainless steel mold. The result showed that condenser effect of Fresnel lens glass was obvious, which is approximately 130 times focus effect. The comparison of the optical simulation and experimental results were carried out and the effects of mold design on the fabrication of manufactured Fresnel lens were demonstrated in this study.

碩士
中華大學
機械工程學系碩士班
96
Glass micro-lens arrays have numerous applications in the field of opto-electronics. Traditional precision glass molding process is too expensive and molding for arrayed glass lenses is difficult to avoid glass sticking and gas bubbles trapped into glass material. This study developed a new process to produce an arrayed glass micro-lenses by gas pressure assisted forming process, which is considered to have a great potential for the mass production of arrayed glass lenses with low cost, ease of manufacture and free of surface defects. Borosilicate glass plates with Transition temperature (Tg) of 560℃ were used in this study. The WC/Co and stainless steel plates with arrayed through holes were employed as the molds. Glass plate was put on the mold and N2 gas was introduced into the closed chamber to allow gas pressure up to 5kg/cm2. IR heating allows the glass plate to approach the soft point, and forces glass flows into the arrayed through holes to form the arrayed glass lenses by viscoelastic deformation. A higher forming temperature, pressure and longer time duration tends to produce the arrayed lenses with a higher peak height and a smaller radius of curvature. The arrayed micro-lenses with peak height of 330 μm can be obtained at the forming temperature of 640℃, gas pressure of 5 kg/cm2 and time duration of 120 s.

碩士
國立成功大學
材料科學及工程學系碩博士班
94
Abstract Mg-based amorphous alloys exhibit highest specific strength among bulk metallic glass systems. In this study, a bulk Mg65Cu25Y10 deposit was produced successfully via spray forming process with higher cooling rate than conventional mold casting route. The deposit is 150mm in diameter, 10 mm in thickness and 650 g in weight. The average porosity is about 10%. The XRD and DSC results of the deposit look similar to that obtained from corresponding amorphous melt-spun ribbon. However, the measured composition of deposit varies slightly with the distance from substrate, which attribute to gravity effect of relative heavy element, like Y and Cu. The deposit is almost amorphous phase from TEM image and diffraction pattern. Twins are induced with deformation for the unique of spray forming process. The supercooled liquid region of the deposit determined from TMA technique is about 20K smaller than that obtained from DSC trace due to the stress induced nanocrystallzation occurred in the former. In addition, the volume reduction of deposit during TMA test was also smaller than that of ribbon and shows better dimension stability. In compressive test，the strength of bulk amorphous alloys is about 269 MPa，strain is about 2.6 %.

The thesis focus on modelling of float glass making process using viscose film type approximation. Navier-Stokes equations are averaged over one spatial variable. Then the domain with an a priory unknown shape, where the shape is a part of the solution, is transformed to a fixed computational domain. The problem is solved by finite element method using FEniCS software. In the end is discussed an influence of several parameters such as wheels, which regulates thickness of the glass and enforce an inner condition, boundary conditions or spreading coefficient on the numerical result. 1