Yazar "Bayram, Fatih" seçeneğine göre listele

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    Determination of reactional cutting forces on a circular sawblade machine by using experimental studies and numerical modelling
    (Sage Publications Ltd, 2012) Yaşıtlı, Nazmi Erhan; Bayram, Fatih; Ünver, Bahtiyar; Özçelik, Yılmaz
    Slab/strip production from blocks in natural stone processing plants is mostly carried out by using circular sawblade cutting machines. An efficient sawing operation can only be maintained by selecting proper cutting parameters. Experimental studies and numerical modelling methods are significant in terms of identifying the effective forces occurring during natural stone cutting with circular sawblades. In this study, experimental investigation was performed on real marble, known as Afyon White Marble, using a fully automatic circular sawblade stone cutting machine. Then, numerical modelling of circular sawing was performed with commercially available software called PFC3D. A discrete-element model of the sawing process was developed, and various numerical models were performed for different peripheral speeds and advance rates in compliance with the actual cutting operation being carried out in the laboratory. Finally, data obtained from the experimental studies were compared with the modelling data. A comparison indicates that the reactional cutting forces obtained by means of the numerical modelling are in good agreement with the results of the laboratory measurements. Consequently, the cutting operation can be determined quickly and economically. A literature review showed that, through this study, numerical modelling of the circular sawblade stone cutting process was successfully performed for the first time. It was envisaged that this would dynamically help in the examination of distinct factors in the area of natural stone processing by numerical modelling and in the illustration of the sawing mechanism.
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    Effects of sawing parameters on natural stone processing performance
    (Sage Publications Ltd, 2013) Bayram, Fatih; Yaşıtlı, Nazmi Erhan
    Circular sawing is a very flexible method used in natural stone processing. This method can be used in all sawing stages, such as tile production, cutting the slabs to size, shaping of cubic pieces, etc. Due to this feature, it is the preferred tool for stone processing. Thus, the investigation of sawing parameters affected on circular sawing performance is necessary. In this study, the effects of some sawing parameters (diamond concentration in segment, sawing depth, and saw blade diameter) on sawing performance (unit wear and unit energy) were investigated through the use of computer-assisted automatic circular sawing machine. Real marble samples, commercially named Afyon Violet, were used in the experiments. It was determined graphically that diamond concentration in segment, sawing depth, and saw blade diameter were very effective on unit wear and unit energy. The statistical analyses were also conducted to determine the effects of sawing parameters on unit wear and unit energy. Consequently, stone processors must take into consideration these sawing parameters in order to achieve more economical production.
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    Experimental and statistical evaluation of cutting methods in relation to specific energy and rock properties
    (Springer Wien, 2013) Engin, İrfan Celal; Bayram, Fatih; Yaşıtlı, Nazmi Erhan
    In a processing plant, natural stone can be cut by methods such as circular sawing (CS), frame sawing (FS), water jet cutting (WJC) and abrasive water jet cutting (AWJC). The efficiency of cutting systems can be compared using various parameters. In this study, the specific energy values were determined and compared to evaluate the efficiency of rock-cutting methods. Rock-cutting experiments were performed on 12 different types of rock samples using a circular sawing machine and an AWJC machine. The experimental results showed that the specific energy values in AWJC were generally higher than in CS. In addition, the relationships between specific energy values and rock properties were explained in this study. The Shore hardness and abrasion resistance were found to be strongly related to the specific energy values, and according to these parameters prediction charts of specific energy values were created.
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    Numerical modelling of mechanized longwall mining with top coal caving in aegean lignite establishment
    (Chamber of Mining Engineers of Turkey, 2013) Yaşıtlı, Nazmi Erhan; Bayram, Fatih; Ünver, Bahtiyar; Kavaklı, Nevzat
    Effective caving of top coal is the most critical factor in maintaining an efficient production in longwall with top coal caving method. During production of the top coal by caving, considerable amount of coal may be left in the goaf and in addition, the produced coal may be diluted with rock, consequently, decreasing the extraction ratio and production efficiency. In this study, numerical studies associated with numerical modelling of Eynez Underground Mine have been carried out. Firstly, the longwall panel was modelled by using a software called FLAC3D, developed based on finite difference technique. Secondary, the induced stresses developing around the longwall face have been determined. Finally, the most critical step of production that is top coal caving through the frames of shields has been modelled. In Eynez Underground Mine, top coal was sufficiently fractured but the marl at the roof was not fractured and there occurred a big opening after caving of top coal. In order to achieve efficient and quick production, the marl must be cracked in as uniformly sized pieces as possible.
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    Optimization of limestone sawing using circular saws with reference to unit wear and energy
    (SAGE PUBLICATIONS, 2013) Bayram, Fatih; Yaşıtlı, Nazmi Erhan; Kulaksız, Seyfi; Özçelik, Yılmaz
    Natural stone processing operations use different methods and machines; however, the circular sawing machines are widely used in natural stone processing since they can be used flexibly. The wear on the diamond segments on the sawblade and energy consumption are the important parameters for these machines. Unit wear and unit energy should be minimized and the sawing rate should be maximized for optimum sawing condition. In this study sawing tests were performed on limestone samples using a fully automatic circular sawing machine. The tests were conducted at different peripheral speeds and advance rates. For each sawing test, the segment wear and consumed energy were measured. The statistical software, Design Expert 7.0 was used to analyze the test data. The new sawability charts for wear and energy were developed. The unique aspect of this study is to determine the optimum circular sawing performance with the special software and this technique also provides the prediction of unit wear and unit energy for selected sawing condition.
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    Predicting mechanical strength loss of natural stones after freeze-thaw in cold regions
    (Elsevier, 2012) Bayram, Fatih
    Natural stones are generally used as building materials for construction and decoration. Determining the deteriorations of stones after freeze-thaw cycles is important subject for natural building stones used in cold regions exposed excessive freezing and thawing during the year. Freeze-thaw test is conducted for determining the deteriorations of stones due to freeze-thaw cycling. The percentage loss in uniaxial compression strength is an important parameter indicating these deteriorations. However, it is extremely laborious and time consuming tests. Because of this, predicting the percentage loss values in uniaxial compression strengths from intact rock properties was the purpose of this paper. Freeze-thaw tests were applied on nine limestone samples selected from different cold regions of Turkey. All of them except two samples were found to be suitable for use in cold regions. A statistical model was developed for predicting the percentage loss values in uniaxial compression strength from intact tests of impact strength, modulus of elasticity and water absorption. This model equation is very reliable (R-2=0.95) and can be very useful for predetermination of uniaxial compression strengths of limestones after freeze-thaw test without testing. (C) 2012 Elsevier B.V. All rights reserved.
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    Prediction of engineering properties of rocks from microscopic data
    (Springer, 2013) Özçelik, Yılmaz; Bayram, Fatih; Yaşıtlı, Nazmi Erhan
    The purpose of this study is to develop the empirical equations for the prediction of the physical and mechanical properties of limestone and marble from microscopic data including their mineralogical and petrographical properties and to test the validity of model equations by using multivariate statistical methods. This study was performed on 15 different rocks, composed of six limestone and nine marble samples. Stepwise multiple regression analysis was applied to predict the engineering properties of both the marble and limestone rock samples considering petrographical properties as inputs. In order to determine the overall significance of the empirical equations for prediction of the physical and mechanical properties of marble and limestone samples, the F test was also performed. As a result of this study, it is found that the empirical equations developed in this study are statistically significant.
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    Prediction of sawing performance based on index properties of rocks
    (Springer, 2013) Bayram, Fatih
    Performance analysis of all systems used in industrial production is very important subject in terms of capturing the low production cost. This subject is also important for choosing production methods in natural stone processing. Circular sawing is a commonly used method in natural stone processing. The preliminary prediction of circular sawing performance is very useful for stone producers. In this study, the prediction of sawing performance from some index properties of stones was conducted. The unit wear on diamond segments was evaluated as performance criteria. The statistical analysis was carried out, and this performance parameter was predicted from some index properties including cone indenter hardness, Shore hardness, Bohme surface abrasion, and brittleness. The most suitable prediction equation derived from regression analysis was selected. It was determined that this equation was statistically reliable for prediction of unit wear for natural stone processing.
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    Tavan göçertmeli uzunayak üretim yönteminde tavan kömürü akma verimliliğinin artırılması
    (TÜBİTAK MAG Proje, 2014) Yaşıtlı, Nazmi Erhan; Bayram, Fatih
    Kalın kömür damarlarında, tavan kömürünün ayak içerisindeki yürüyen tahkimatların oluklardan akıtılarak üretilmesi ilkesine dayanan uzunayaklarda, tavandan üretilen kömür ayaktan üretilen kömürün iki katından daha fazla olduğu için tavan kömürü çok dikkatli ve özenli bir şekilde üretilmelidir. Tavan kömürünün akıtılırken göçüğe karışması rezerv kazanım oranının azalmasına ve dolayısıyla üretim veriminin düşmesine neden olmaktadır. Ayrıca bu durum ayak arkasında oluşabilecek yangın riskini de artırmaktadır. Bu çalışma kapsamında, tavan kömürü göçertmeli tam mekanize uzunayak üretim yöntemini uygulayan Garp Linyitleri İşletmesi (GLİ) Ömerler Yeraltı Ocağının ve Ege Linyitleri İşletmesi (ELİ) Eynez Yeraltı Ocağının, ayrık elemanlar ilkesine göre çalışan PFC3D programı kullanılarak üç boyutlu modelleri oluşturulmuştur. Öncelikle ayak çevresinde oluşan gerilmeler tespit edilmiştir. Daha sonra, akma modelinde kullanılacak parametreler belirlenmiştir. En sonunda, üretimin en önemli aşaması olan tavan kömürünün göçertilmesi ve tahkimat oluğundan akması modellenmiştir.