4,154 research outputs found
Feedrate optimisation/scheduling on sculptured surface machining: a comprehensive review, applications and future directions
No full textFree-form or sculptured surface milling is one of the continually used manufacturing processes for die/mould, aerospace (especially turbine blades), precision machine design, bio-medical devices and automotive industries. Developments of machining technologies for quality enhancement of machining results have become a very important fact in current real industry. Therefore, reducing milling time, tool wear, cutter deflection and improving surface texture quality and machining operations through adaptation and optimisation of tool feedrates based on changing surface geometry in sculptured surface machining is a great step in this direction. Various feedrate optimisation strategies have different feedrate rescheduling control parameters such as chip thickness, material removal rate (MRR), min(mrr,chip,force), max(expo.Acc/dec) and resultant forces. Some commercial CAM softwares come with MRR-based feedrate optimisation algorithms which have a very short calculation time. However, commercial feedrate scheduling systems have some limitations in generating the scheduled feedrates because they use the MRR or the cutting force model which is dependent on milling conditions. However, for the processes in which machining precision/accuracy is very important, it is inevitable that mechanistic force-based feedrate optimisation approaches, for which the calculation time is improved, will be integrated into commercial CAM software packages. Here, developing only the mechanistic cutting force-based algorithm is not enough. In this paper, improvement and optimisation of machining feedrate value, which is one of the cutting parameters which has a tremendous effect on the precise machining of free-form surfaces, was discussed by using the virtual machining framework. For this purpose, the boundary representation solid modelling technique-based free-form milling simulation and feedrate optimisation system integrated with commercial CAD/CAM software is developed for three-axis ball-end milling. This review study includes the information regarding the following topics: The algorithms developed for the feedrate value optimisation, MRR calculation approaches, cutting force computation methods, details of algorithms, the effects on the surface accuracy, the effects on the machining time, the capabilities of the present commercial CAM software packages, the encountered difficulties and overcoming those difficulties, recent developments and future research directions
Optimum Tool Selection by Artificial Neural Networks
No full textCNC tezgahlarda üretime başlamak için; CNC programının hazırlığı, uygun takımların seçimi ve tareteyerleştirilmesi ve buna ilave olarak, parçanın uygun aparat veya aynaya emniyetli bir şekilde bağlanması gerekir.CNC Torna tezgahlarında kullanılan programlar CAD/CAM yazılımları vasıtasıyla ISO kodunda üretilir. Buradakesmede kullanılacak takımın seçilebilmesi için iyi bir takım bilgisine ihtiyaç vardır. Bu bilgiye sahip olmakuzun bir deneyim ve mesleki bilgiyi gerektirmektedir. Bu çalışmada, DXF formatındaki parça profili eldeedildikten sonra eldeki takım kütüphanesi, tezgâh özelliklerini ve kesilecek malzeme bilgilerini dikkate alaraktakım seçme işlemini Yapay Sinir Ağları (YSA-kısaltma ve bundan sonra bu kısaltma kullanılabilir) Yöntemikullanılarak otomatik olarak yapmaktadır. Ayrıca, bu çalışmada mevcut olan CNC programı okunarak buradanişlenecek olan iş parçası profili oluşturulmaktadır. Bu oluşturulan parça profili esas alınarak, yine Yapay SinirAğları yöntemiyle uygun takımlar otomatik olarak seçilmektedir. Seçilen takımların listelenmesi ve resimleriningösterilmesi sayesinde takım dolabına gitmeden takım tanınmakta ve böylece zaman kaybı olmadan eldeki-altcümle ile birleştirilmeli takımlardan en uygun olanı program sayesinde seçilmektedir.In order to start the operation in the CNC machine, the preparation of the CNC, the selection and_x000D_
positioning of appropriate tools should be done and the tool should be securely tightened on a scroll chuck or a_x000D_
device. The programs used in the CNC Lathe are produced with the aid of the CAD/CAM in ISO code. In order_x000D_
to able to select the tool that is going to be used in the cutting process, it is necessary to have a good knowledge_x000D_
of tools. To acquire this knowledge should have experience and professional training. In this study, automatic_x000D_
tool selection process is completed by using Artificial Neural Network Method from the tool Library after_x000D_
recognizing workpiece profile from the DXF format together with the necessary data about machine tools_x000D_
specification and workpiece materials. In addition, workpiece profile is created by using the CNC program in this_x000D_
study. This workpiece machining profile is taken as a reference for selecting appropriate tools
The life-works and art of Mustafa Balel
No full textMustafa Balel (1945- ) 1972'de Yeni Ortam'da başlayıp günümüze uzanan yazarlık hayatında toplumsal gerçekleri konu etmesi ve ayrıntıları sivriltmesi ile döneminin yazarlarından ayrılır. Sanat hayatı boyunca başta öykü olmak üzere roman, anlatı, gezi yazısı ve çocuk edebiyatı alanlarında eserler vermiştir. Balel, toplumdaki yapıyı eserlerinde okura sunmuştur. Bu bağlamda yazar, Türk toplumunun sanıldığı gibi ataerkil değil anaerkil bir yapıda olduğu görüşünü savunmaktadır. Bu durum eserlerinde baskın kadın tiplerini de beraberinde getirmiştir. Yazarlık hayatı boyunca hiçbir zaman realizmden kopmayan Balel, yaşamın kendisini eserlerine taşımıştır. Bunu yaparken de gerçekleri olduğu gibi söyleyen çocuk anlatıcılardan yararlanmıştır. Toplumdaki sosyoekonomik yapıya dayanan sınıf ayrımını eserlerinde vurgulayan yazar, toplumsal gerçekçi bir çizgiye sahiptir. Daha çok aile, şiddet, kadın hâkimiyeti, yalnızlık ve göç temalarını konu etmiştir. Ele aldığı toplumsal konulara paralel olarak dilde de halktan kopuk bir tutum izlemeyen Balel, daha çok halkın yöresel söyleminde yer edinen deyim ve atasözlerinden faydalanmıştır. Bu karakteristik özellikleri farklı edebî türlerde kaleme aldığı eserlerinin tamamında görülür.Mustafa Balel (1945- ) whose career as a novelist started with Yeni Ortam (New Circumstances) in 1972 and pursued up to now is distinguished from his contemporaries as depicted social realities and sharpened details. During his art career, he produced novels, stories, narration, itineraries and works in children?s literature. Balel has presented the social structure to readers. In this context, the author argues that Turkish society is not a patriarchal as supposed but matriarchal. This case has lead to dominant women characters in his works. Balel, who have always stuck to realism, reflected his own life in his works. While doing this, he made use of children narrators who tell the truth as it is. The author who emphasizes social stratification in his works which is based on socioeconomic structure follows a social realistic line. In his works, he mostly treated family, violence, women dominancy, loneliness and immigration. In parallel with social issues he handled, Balel used idioms and proverbs established in people?s local language and thus did not have a language style different from people. This characteristic is seen in all his works in different literature genres
Design and Examination of Mobile Application Interface Facilitating the Lives of Individuals with Diabetes
No full textDiyabet; genel olarak kanda bulunan glukoz seviyesinin normal seviyenin üzerine çıkması, buna bağlı olarak normalde şeker içermemesi gereken idrarda, şekere rastlanması durumu olarak bilinmektedir. Diğer adı diabetes mellitus olan hastalık,dünyada en çok görülen hastalıklar arasında yer almaktadır. Diyabet hastalığına genetik ve çevresel faktörlerin sebep olduğu görülmektedir. Hastalığın ortaya çıkma sebepleri Tip 1 Diyabet ve Tip 2 Diyabet olmak üzere farklılık göstermektedir. Bu çalışmada, diyabet hastalığı olan bireylerin hayatlarını kolaylaştıracak olan mobil uygulama ara yüz tasarımı yapılmıştır. "Yaşam Tarzı Diyabet" isimli bu uygulama sayesinde bireyler doktorlarıyla kolay iletişim kurabilecek, hastalık değer takibi yapabilecek ve birçok işlemi bu uygulama sayesinde kolaylıkla halledebilecektir.Diabetes; In general, the increase of the glucose level in the blood above the normal level _x000D_
is known as the presence of sugar in the urine, which should not normally contain sugar. _x000D_
Diabetes mellitus is one of the most common diseases in the world. Diabetes is caused by _x000D_
genetic and environmental factors. The disease is of two types, type 1 and type 2, _x000D_
depending on the cause of its occurrence. In this study, a mobile application interface _x000D_
design has been designed to facilitate the lives of individuals with diabetes. With this _x000D_
application called "Lifestyle Diabetes", individuals will be able to communicate easily _x000D_
with their doctors, follow up measurements and handle many processes easily thanks to _x000D_
this application
The use of interactional metadiscourse : a comparison of articles on Turkish education and literature
No full textThis study aims to determine the use of interactional metadiscourse in articles from the domains of Turkish language and literature. The study employed a descriptive research model to examine 20 articles from the Mustafa Kemal University Journal of Social Sciences Institute (all articles were published between 2010 and 2015 and each has only a single author). Of these randomly selected articles, 10 were on Turkish language education and 10 were concerned with Turkish literature. Hyland and Tse's metadiscourse model was adopted to examine markers of interactional metadiscourse in all fundamental parts of these articles. For the evaluation of the obtained data, the content analysis technique and the Mann-Whitney U test were used to determine whether the interactional metadiscourse demonstrates any significant differences regarding the domains of Turkish language education and literature. Experts were consulted to ensure the reliability of the research. As a result, this study revealed that there is more use of interactional metadiscourse markers in the field of Turkish language education than in the field of literature, and this difference is significant, according to the Mann-Whitney U test. Further, it was found that hedges and boosters demonstrate a significant difference in studies on Turkish language education and literature; however, no significant difference in the uses of attitude markers, engagement markers, and self-mentions was observed.This study aims to determine the use of interactional metadiscourse in articles from the domains of Turkish language and literature. The study employed a descriptive research model to examine 20 articles from the Mustafa Kemal University Journal of Social Sciences Institute (all articles were published between 2010 and 2015 and each has only a single author). Of these randomly selected articles, 10 were on Turkish language education and 10 were concerned with Turkish literature. Hyland and Tse's metadiscourse model was adopted to examine markers of interactional metadiscourse in all fundamental parts of these articles. For the evaluation of the obtained data, the content analysis technique and the Mann-Whitney U test were used to determine whether the interactional metadiscourse demonstrates any significant differences regarding the domains of Turkish language education and literature. Experts were consulted to ensure the reliability of the research. As a result, this study revealed that there is more use of interactional metadiscourse markers in the field of Turkish language education than in the field of literature, and this difference is significant, according to the Mann-Whitney U test. Further, it was found that hedges and boosters demonstrate a significant difference in studies on Turkish language education and literature; however, no significant difference in the uses of attitude markers, engagement markers, and self-mentions was observed
Identification of static surface form errors from cutting force distribution in flat-end milling processes
No full textThis paper presents a new and practical process simulation method to analyze surface errors caused by deflections of statically flexible flat-end mills. Milling force and surface error models are established to predict the surface error in various cutting conditions. The milling forces are predicted from the mechanistic model extended using the force distribution determined with an effective calibration procedure carried out by experimentally dividing the cutting part of the end mill into discs. The surface errors are modeled by establishing an analytical relationship between bending moments and deflections by means of the cantilever beam theory. These features make the present method very practical and efficient. A set of computational studies and experiments is performed to validate the effectiveness of the presented method. Comparisons of the results obtained numerically and experimentally confirm that the method is capable of accurate prediction of milling forces and surface errors. Finally, this method can be effectively applied for identifying appropriate cutting conditions in flat-end milling
Determination of Surface Qualities on Inclined Surface Machining with Acoustic Sound Pressure
No full textDie parts used in automotive and aviation industry have complicated surfaces that require multiaxis machining. In machining of inclined surfaces with ball-end milling, the process is of great significance for its correctness and accuracy. In this study, Acoustic Sound Pressure (ASP) generated during the machining of a workpiece at a vertical machining centre has been measured. The experiments have been conducted in association with cutting velocity, feed rate and step over parameters determined by using different surface forms and different cutter path strategies. Therefore, the aim of this study is to understand the relationships between the generated sound signals and surface roughness in the machining of inclined concave and convex surfaces. In the experiments, the workpiece material of EN X40CrMoV5-1 hot work tool steel, which is commonly used in the related die industry, has been chosen. The ball end mills with two indexable inserts with three different coatings of TiC, TiN, and TiAlN have been used. The results show that there is a rise at the value of surface roughness with a rise at the value of acoustic sound pressure and that surface roughness could be figured out with acoustic sound pressure level
Application of Taguchi methods in the optimization of cutting parameters for surface finish and hole diameter accuracy in dry drilling processes
No full textThe aim of the work reported here was to utilize Taguchi methods to optimize surface finish and hole diameter accuracy in the dry drilling of Al 2024 alloy. The parameters of hole quality are analyzed under varying cutting speeds (30, 45, and 60 m/min), feed rates (0.15, 0.20, and 0.25 mm/rev), depths of drilling (15 and 25 mm), and different drilling tools (uncoated and TiN- and TiAlN-coated) with a 118A degrees point angle. This study included dry drilling with HSS twist drills. The settings of the drilling parameters were determined by using Taguchi's experimental design method. Orthogonal arrays of Taguchi, the signal-to-noise (S/N) ratio, the analysis of variance (ANOVA), and regression analyses are employed to find the optimal levels and to analyze the effect of the drilling parameters on surface finish and hole diameter accuracy values. Confirmation tests with the optimal levels of machining parameters are carried out in order to illustrate the effectiveness of the Taguchi optimization method. The validity of Taguchi's approach to process optimization is well established
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