Led tv için ortadan ayak tasarımı ve analizi
Central stand design and analysis for led tv
Yazar: BAHTİYAR YILMAZ
Danışman: YRD. DOÇ. DR. İBRAHİM MEHMET PALABIYIK
İstanbul Teknik Üniversitesi / Fen Bilimleri Enstitüsü / Makine Mühendisliği Ana Bilim Dalı / Konstrüksiyon Bilim Dalı
Derece: Yüksek Lisans, 2016
Konu: Makine Mühendisliği = Mechanical Engineering
Dizin: Akış analizi = Flow analysis ; Basınçlı döküm = Pressure die casting ; Bilgisayar destekli analiz = Computer aided analysis ; Bilgisayar destekli tasarım = Computer aided design ; Statik analiz = Static analysis

Özet:
Televizyonlar 21. Yüzyıl'ın başlarından itibaren, sadece kanalların izlenebildiği elektronik eşya kavramından ayrışmaya başladı. Android tabanlı işletim sistemleri ve 8K ekran çözünürlüğünün yanında, ekran teknolojisindeki gelişmeler daha büyük ve daha ince televizyonların üretimini mümkün kılarak mekanik anlamda estetik tasarımları ön plana çıkardı.
Bu çalışmada 32", 40" ve 55" LED TV için ortak kullanılacak ortadan ayak tasarımı yapılmış; daha sonra bu tasarım statik kuvvet analizi, akış simülasyonu ve testlerle doğrulanmıştır.
Giriş bölümünde, günümüzde teknolojinin geldiği yerden ve televizyonun müşteriye görsel anlamda ne sunduğundan bahsedilmiştir. Tezin amacı ortaya konulmuş, literatürdeki örnekler aktarılmış ve hipotez belirlenmiştir.
İkinci bölümde, ayak çeşitleri incelenmiş; hareket çeşitlerine ve yapılarına göre bir sınıflandırmaya gidilmiştir. Yapılarına göre ayaklar; sac metal taşıyıcı ayaklar, alüminyum taşıyıcı ayaklar, plastik taşıyıcı ayaklar ve tek parça plastik ayaklar olarak ayrılırken, hareket şekline göre sabit ve hareketli olarak ayrılır. Hareketli ayaklar da kendi içinde tilt ve swivel olarak ikiye ayrılır.
Üçüncü bölümde, ayağın tasarımı yapılırken; ön tasarım ile ayağın genişliği ve uzunluğu belirlenmiş, detay tasarımda ise ayak grubunu oluşturan alüminyum taşıyıcı, plastik kapak, boyun parçası ve kozmetik plastik parçalarının tasarım prensipleri ve üretim teknolojileri ile ilgili bilgiler verilmiştir.
Dördüncü bölümde, detay tasarımı tamamlanmış ayak grubu içindeki en kompleks ve kritik parça olan alüminyum taşıyıcı 100 N kuvvet testini simule etmek için statik analize ve enjeksiyon prosesindeki malzeme davranışını görmek için akış analizine tabi tutulmuştur. MSC Nastran yazılımı ile yapılan statik analizde; deplasman, düşey deplasman, yatay deplasman, temas durumu, esneme miktarı, eşdeğer Von-Mises gerilmesi ve noktasal düşey deplasman incelenmiştir. Akış analizinde MAGMASOFT yazılımı kullanılmış olup; dolum sıcaklıkları, dolum hızları, dolum hava hapsolmaları, dolum hava kalan bölgeler, dolum türbülansları, katılaşma sıcaklıkları ve katılaşma sonra çarpılmalar incelenmiştir. Yapılan analizlerden sonra 100 N kuvvet testi ve 10°lik eğik düzlem testi uygulanmış ve deneysel analiz başlığı altında sonuçları paylaşılmıştır.
Sonuç bölümünde ise ayak grubunun tasarım ve analiz süreçlerinin üstünden geçilirken, sorunsuz alınan deneme baskılarından örnekler paylaşılmış ve ürünün seriye giriş tarihi okuyuculara aktarılmıştır.

Abstract:
Since the beginning of the 21st century, televisions began to separate from the concept of electronic goods can be viewed only channel. Besides Android-based operating system, and 8K screen resolution, advances in screen technology has brought to the fore mechanically aesthetic design, enabling the production of thinner and larger televisions.
In this study, central stand was designed for 32", 40" and 55" LED TV; then this design was confirmed by static strength analysis, flow simulation and tests.
In the introduction, it has been mentioned where today's technology comes from and what televisions offers customers visually. The aim of this thesis has been put forward, examples in the literature have been transferred and the hypothesis has been determined.
Large-screen television technology developed rapidly in the late 1990s and 2000s. Various thin screen technologies are being developed, but only the liquid crystal display (LCD), plasma display (PDP) and Digital Light Processing (DLP) have been released on the public market. These technologies have almost completely displaced cathode ray tubes (CRT) in television sales, due to the necessary bulkiness of cathode ray tubes. However, recently released technologies like organic light-emitting diode (OLED) and not-yet released technologies like surface-conduction electron-emitter display (SED) or field emission display (FED) are making their way to replace the first flat screen technologies in picture quality. The diagonal screen size of a CRT television is limited to about 40 inches because of the size requirements of the cathode ray tube, which fires three beams of electrons onto the screen, creating a viewable image. A larger screen size requires a longer tube, making a CRT television with a large screen (50 to 80 inches) unrealistic because of size. The aforementioned technologies can produce large-screen televisions that are much thinner.
In the second chapter, stand types have been examined; were made of a classification according to motion types and structures. According to structure, there are sheet metal based stands, aluminium based stands, plastic based stands and a single piece plastic stands. According to motion type, there are fixed, tilt, swivel and mixed (swivel with tilt together) types.
In the third chapter, while have been designing of the stand; the width and length have been determined in preliminary design. It has been informed that design principles and production technologies of parts of the stand group which is aluminium base, plastic cover, neck piece and cosmetic plastic.
High pressure die casting (HPDC) is an important process in the manufacturing of high volume and low cost components, such as automatic transmission housing and electric/electronic housing, an economical and efficient method for producing components requiring low surface roughness and high dimensional accuracy. High pressure aluminium castings offer the automaker design, mass, and quality advantages in key body structure applications such as pillars, shock towers, and floor rails, to name just a few. Complex shapes, high product durability, and efficient integration with mating components can be achieved. Traditional body structure design would typically have multiple components welded together in areas now combined in a single aluminium casting, accomplishing the same function with less variability and less mass.
Plastic injection molding is a manufacturing technique for making parts from both thermoplastic and thermosetting plastic materials in production. Molten plastic is injected at high pressure into a mold, which is the inverse of the product's shape. After a product is designed, usually by an industrial designer or an engineer, molds are made by a moldmaker (or toolmaker) from metal, usually either steel or aluminium, and precision machined to form the features of the desired part. Injection molding is widely used for manufacturing a variety of parts, from the smallest component to entire body panels of cars. Injection molding is the most common method of production, with some commonly made items including bottle caps and outdoor furniture.
PC/ABS (Polycarbonate/Acrylonitrile Butadiene Styrene) is a blend of PC and ABS providing unique combination of the high processability of ABS with the excellent mechanical properties, impact and heat resistance of PC. The PC/ABS property balance is controlled by the ratio of PC and ABS in the blend, the polycarbonate molecular weight and the additive package. The ratio of polycarbonate and acrylonitrile-butadiene-styrene affects mainly the heat resistance of the final product. PC/ABS blends exhibit a synergic effect resulting in excellent impact resistance at low temperatures that is better than impact resistance of ABS or PC.
In the injection molding process, tool temperature is an important factor in achieving high-quality parts. It is generally believed that higher tool temperature often results in better surface quality. There are various dynamic variotherm technologies, including Heat & Cool, Induction Heating Molding (IHM) and Electricity Heating Mold (E-Mold)… etc. Among these advanced technologies, some increase temperature in the entire moldbase; some increase temperature only on the mold surface. But in reality, mold temperature control mechanism is extremely complex; therefore, performing and managing those variotherm technologies is very challenging in injection molding system.
Hot stamping is the process of transferring a very thin coating (typically metallic) on to paper or plastic through a combination of heat and pressure. Typical decorative applications of hot stamp foils include greeting cards, book covers and packaging media, such as labels and folding cartons. Transfer foils can also be found embellishing writing instruments, cellular telephones and cosmetics. In these cases, the hotstamp foils are primarily for promotional purposes or aesthetic appeal.
Aluminium extrusion is an industrial forming process to produce long profiles of a constant cross-section. Aluminium rods (billets) are heated and pressed through a die to obtain the product's cross-sectional shape. The most common type of extrusion is direct extrusion, where the ram of the press pushes the aluminium billet through a stationary die. The most common type of press for this process is the horizontal hydraulic press. Press capacities vary according to the size of the dies used, which can have diameters between 100 and 1000 mm. For the most common extruded products, dies of 175 to 250 mm in diameter are used. For these die diameters presses with capacities between 1500 and 2000 metric tons are required.
Anodising is a process for producing decorative and protective films on articles made from aluminium and its alloys. It is essentially a process where a thick film of aluminium oxide is built up on the surface of the aluminium through the use of a direct current electrical supply. Aluminium alloys are anodized to increase corrosion resistance and to allow dyeing (coloring), improved lubrication, or improved adhesion. However, anodizing does not increase the strength of the aluminium object. The anodic layer is non-conductive.
In the fourth chapter, aluminium base which is the most complex and critical part of the stand group has been subjected to static analysis to simulate 100 N force test and flow analysis to see the behavior of materials in injection process. Displacement, vertical displacement, horizontal displacement, contact situation, flexing amount, equivalent Von Mises stress and point-vertical displacement have been analyzed in static analysis performed by MSC Nastran software. In flow simulation performed by MAGMASOFT software, filling temperature, filling velocity, air entrapment, last air, filling turbulence, solidification temperatures and displacements after solidification have been analyzed. Following the performing analysis 100 N force test and 10° inclined plane test have been applied and results have been shared under the title of experimental analysis.
In the conclusion, design and analysis processes of stand group have been worked over, examples of trial injection parts taken smoothly have been shared and readers have been informed about mass production date of product.