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Hesaplamalı akışkanlar dinamiği ile cam şekillendirilmesinin modellenmesi

Modelling glass forming using computational fluid dynamics

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  1. Tez No: 920893
  2. Yazar: RAMAZAN ERGİN SAĞLAM
  3. Danışmanlar: PROF. DR. KADİR KIRKKÖPRÜ
  4. Tez Türü: Yüksek Lisans
  5. Konular: Mühendislik Bilimleri, Engineering Sciences
  6. Anahtar Kelimeler: Belirtilmemiş.
  7. Yıl: 2025
  8. Dil: Türkçe
  9. Üniversite: İstanbul Teknik Üniversitesi
  10. Enstitü: Lisansüstü Eğitim Enstitüsü
  11. Ana Bilim Dalı: Makine Mühendisliği Ana Bilim Dalı
  12. Bilim Dalı: Isı-Akışkan Bilim Dalı
  13. Sayfa Sayısı: 125

Özet

Cam üretim prosesinde yüksek miktarda enerji ve hammadde kullanılmaktadır. Enerji kaynağı olarak fosil yakıtlar başta olmak üzere ek olarak da düşük miktarda yenilenebilir kaynaklara ihtiyaç duyulmaktadır. Hem emek hem de enerji yoğun olan bu sektörde, verimliliklerin en üst noktada tutulması firmaların pazarda rekabet şansını arttırmaktadır. Günümüz dünyasında enerji kaynaklarının tükenmesi nedeniyle kullanılacak tüm girdilerden en üst seviyede faydalanmak, şirketlerin ayakta kalması açısından yararlı olacaktır. Son zamanlarda yaşanılan enerji ve hammadde krizleri sebebiyle de şirketler, kaynaklarını doğru bir şekilde yönetmenin yollarını aramaktadır. Bu çalışmanın amacı, pres ve pres-üfleme prosesleri ile sofra camı üretiminde yapılan deneme sürelerinin kısaltılması, deneme sayılarınn azaltılması ve ürün gramajlarının optimize edilmesidir. Camın makine ortamında şekillendirilmesi, bilgisayar ortamında modellenerek prosesi etkileyen parametrelerin anlaşılması da hedeflenmiştir. Deneme imalatlarının modellenmesi ve çözümü, bilgisayar ortamında gerçekleştirilerek istenen kalitede ve en uygun gramajda ürün elde edilmesinin yanında, yeni ürünün seri imalata geçiş süresi mevcut duruma göre 8 hafta kısaltılabilmektedir. Ayrıca imalat hatlarındaki deneme kaynaklı duruşların ve deneme maliyetlerinin ortadan kaldırılması hedeflenmektedir. İlave olarak, yapılacak analizler ile üründe istenilen cidar kalınlığını öngörmek ve imalat sırasında meydana gelen ağızda çapak, yarım ağız, dip kayığı ve mastör-cam yapışması gibi imalat hatalarının önüne geçilmesi amaçlanmıştır. Bu proje kapsamında, imalatı yapılan bir üründe kaliteyi arttıracak ve maliyeti düşürecek cidar inceltme, ürün gramajı düşürme, uygun parizon tasarımı vb uygulamaların bir Hesaplamalı Akışkanlar Dinamiği (HAD) yazılımı ile önceden belirlenip gerekli çalışmaların hayata geçirilmesi hedeflenmektedir. Aynı zamanda, yeni bir ürünün üretilebilirliğinin HAD sayesinde iki veya daha fazla deneme yapılmadan anlaşılabilmesi planlanmaktadır.

Özet (Çeviri)

In the glass manufacturing process, large amounts of energy and raw materials are used. Fossil fuels are primarily used as the energy source, with additional but small amounts of renewable resources also required. In this labor and energy intensive industry, maintaining maximum efficiency increases companies' chances of competing in the market. Given the depletion of energy sources in the modern world, maximizing the use of all inputs will be beneficial for companies to stay efficient. Due to recent energy and raw material crises, companies are actively searching for ways to manage their resources effectively. The aim of this study is to shorten the trial periods, reduce the number of trials, and optimize the product weights in the production of tableware glass using pressing and press-blowing processes. The modeling and solving of trial productions are carried out in a computer environment, ensuring the desired quality and optimal weight of the product. In addition, the transition time of a new product from prototype to mass production can be reduced by 8 weeks compared to the current process. The goal is also to eliminate trial-related stoppages on the production lines and reduce trial costs. Additionally, through the analysis, the desired wall thickness of the product will be predicted, and production defects such as split finish at the mouth, half-mouth, wedge bottom or mould-glass adhesion will be prevented. Within the scope of this project, wall thinning, weight reduction, appropriate parison design, and similar applications that will increase quality and reduce cost in the production of a product will be pre-determined using Computational Fluid Dynamics (CFD) software, and the necessary actions will be implemented. Furthermore, it is planned that the manufacturability of a new product can be understood using CFD without the need for two or more trials. The introduction covers the basic properties of glasses and the production methods of silica-based glasses in mass production. The manufacturing methods are used in tableware glass production introduced, and the components of the production line are listed. A literature review has been conducted for the investigation of glass properties. The most important properties of glass for modeling are; viscosity, specific heat, density, and thermal conductivity. These physical properties change with temperature and depend on the glass chemical composition and temperature. The viscosity, heat capacity, thermal conductivity, density and thermal expansion of glass are particularly important for numerical modeling. These four properties required for modeling are explained, and the values are determined in computational fluid dynamics (CFD) software. In order to determine the temperature-dependent viscosity parameter, the Vogel-Fulcher-Tammann (VFT) model was chosen, and glass samples taken from the factory were sent to an international glass research institute. Viscosity values corresponding to specific temperatures were calculated using a rotational viscometer, and a temperature-dependent viscosity graph was created using the VFT model. Viscosity test results were compared with another commercial software is used in the factory, and it was concluded that they could be used as input data for analysis. Modeling of glass forming has developed over the years. Early works remained within the boundaries of assumptions. With supporting studies, glass forming modeling has been improving. The finite element analysis method is one of the most commonly used methods in glass forming processes. The finite element analysis method can be applied to both pressing and blowing stages. In cases with significant deformation, the use of adaptive or variable mesh structures is preferred. The most widely used commercial software in the industry are ANSYS Polyflow (Finite Element Method), Fluent (Finite Volume Method), and NOGRID (Finite Point Method). In this study, ANSYS Polyflow was chosen. While using the ANSYS Polyflow module for glass forming modeling, it is essential to define some important points. During the rapid forming process, the glass changes shape, and its temperature decreases significantly. Therefore, key factors of ANSYS Polyflow are specified. Molds play several roles in the process and the most important role of molds are shaping the glass and extract heat from the glass. Understanding this phenomenon between the mold and the glass will increase the accuracy of the forming model. However, heat transfer between the glass and the mold is inherently a complex and difficult process to understand. Additionally, there is no exact analytical solution for it. Therefore, experimental setups or data collection from production machines are required to determine the heat transfer at the glass-mold interface. In an industrial-scale study, high-speed, removable K-type thermocouples were placed at some internal points of the mold. The heat transfer coefficient value used in this project was derived from data sets obtained from experimental results conducted at the industrial scale. To understand the glass forming process under industrial scale and manufacturing conditions, the mass, momentum, and energy conservation differential equations must be solved by the program. For modeling purposes, glass is assumed to be incompressible flow. The studies have been solved in 2D or 3D. Some products can be assumed to be axisymmetric due to their shape, and thus, solutions can be performed in 2D. For the investigation of wall distribution in the press-blow process, 2D analyses are sufficient. However, 3D solutions will be required for modeling, products like in the pressing process, which are not axisymmetric. After obtaining information from the literature review, products for experimentation were selected for the computer environment. Manufacturing data was recorded, and modeling was performed. The shaping steps for the pressing, press-blowing, and“individual section”IS production processes were analyzed. These processes include; isothermal teacup pressing process, non-isothermal teacup pressing process, non-isothermal decanter press-blowing process, non-isothermal IS parison pressing process, and coke glass pressing, sagging, and blowing processes. The analysis results have been examined for each process The results of the analysis are explained in the conclusions section, and future work plans have been created. Using HAD software to predict product wall thickness without conducting tests can provide cost and time advantages to companies. In particular, work continues to investigate and improve measurement methods to make inputs more comprehensive and accurate. Some parameters were used in the study obtained as a result of the literature review. Collecting and compiling the data to be used in the computer environment is of great importance. Furthermore, understanding this data will influence the results. To calculate the heat transfer coefficient that changes according to operating conditions in glass modeling, measurements must be made in real-time during the forming process. Feedback from the manufacturing field is required to train the parameters used in the program. Differences may occur between the products produced in the machine environment and those modeled in the computer environment. The use of the ANSYS Polyflow module in both the pressing and press-blowing processes seems promising. It can be especially useful in steps such as improving parison design and determining the wall thickness distribution of the product. Replacing the Newtonian fluid viscosity model with a non-Newtonian fluid model in the press-blowing process, particularly in the sagging and blowing steps, will produce more accurate results for determining wall thicknesses. The effect of shear thinning under machine conditions is observed for long and heavy parisons.

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