Yayınlar

1STRESS EVALUATION OF ASYMMETRIC AND SYMMETRIC SPUR GEAR FORGING DIES USING FINITE ELEMENT METHOD

Özet

Prediction of the stresses of precision gear forging die is becoming increasingly essential and it also important to make the precision gear forging feasible. The usual way to design gear forging die is to use thick cylinder approach (Lame Equations). However, the finite element method (FEM) has been greatly successful to provide the understanding of die stresses for different forming process. The aim of this study is to evaluate the stresses on simple cylindrical, symmetric and asymmetric gear forging dies by applying internal pressure from 20% to 100% of inner surface of the dies. For this purpose, 3D FE analyses were carried out and the stresses encountered in partially pressurized forging dies were evaluated. The results show that partially loaded die has subjected to lower stresses than the fully loaded one and the maximum effective stresses are linearly increasing with increasing pressurized area. The value of maximum equivalent stresses is higher in gear shaped dies than the cylindrical one and asymmetric gear die is encountered to the highest stresses. The cylindrical approach (Lame Equations) is not adequate for gear forging die design.

Authors: Omer Eyercioglu, Necip Fazil Yilmaz, Gulaga Tas, Mehmet Aladag
Proceeding Book: VI. International GAP Engineering Congress 2018
Pages: 417-425
ISBN:9789757113683
Full Text
2BAĞLANTI ELEMANLARI ŞEKİLLENDİRME KALIPLARININ AŞINDIRICI AKIŞKAN YÖNTEMİYLE PARLATILMASI

Özet

Bu çalışmada, bağlantı elemanları (cıvata, somun vb.) kalıplarının yüzey parlatma işlemlerinde aşındırıcı akış işleme yöntemi(AFM) kullanılmıştır. Tel elektro-erozyon ile kesilen kalıp bileşenlerinin, yüzey pürüzlülüğü, aşındırıcı akışkanla işleme öncesi ve sonrasında ölçülerek yüzey kalitesinin değişimi incelenmiştir. Bulgular, elektro-erozyon nedeniyle oluşan beyaz katman tabakasının tamamen ortadan kaldırıldığını ve son yüzey pürüzlülüğünün (Ra) 1,5 µm'den 0,4 µm'ye azaltıldığını göstermiştir. Yüzey kalitesinin artışı, kalıp malzemesinin sertliğiyle orantılıdır.  

Keywords: Aşındırıcı Akışkanla İşleme, Dövme Kalıbı, Yüzey İşlemleri
Authors: Omer EYERCIOGLU, Kürşad GÖV, Adem AKSOY, Mehmet ALADAG
Dergi: Makina Tasarım ve İmalat Dergisi
ISSN:1302-9487
Makaleyi İndir
3ASYMMETRIC SPUR GEAR MEASURING BY USING DIGITAL IMAGE PROCESSING TECHNOLOGY

Özet

The measurement of the asymmetric gear tooth is difficult due to the asymmetricity of profile, so a method based on image processing to measure the error of the asymmetric spur gear is presented. Non-contact measurement for asymmetric spur gear was investigated using image processing technology. The digital image of the asymmetric spur gear is captured by the CMOS camera and the software is developd by using Python and as OpenCV image processing library. Some digital image processing techniques and algorithms are used, including distortion correction, frame resizing, color conversion, median filter, binarization, edge detection, and sub-pixel fitting arithmetic. According to the shape feature of the asymmetrical gear, some basic principles such as fit to least squares, Hough transformation and Bresenham drawing circle were applied synthetically and the measurement algorithm of the number of teeth, module, radius of center, radius of addendum, radius of dedendum, coefficient of variation, etc. was established. The experimental results show that this method satisfies the requirements of real-time inspection. 

Keywords: Digital image processing, asymmetric spur gear, non-contact measuring, Python, OpenCV
Authors: Omer EYERCIOGLU, Mehmet ALADAG
Proceeding Book: 2. Uluslararası Türk Dünyası Mühendislik ve Fen Bilimleri Kongresi
ISBN:978-605-80038-4-2
Pages: 524-531
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4COMPARISION OF WARM AND HOT PRECISION FORGING PROCESS OF ASYMMETRIC SPUR GEAR

Özet

Asymmetric gears are those have two different pressure angles for drive and cost side of the gear. Because of this speciality of the asymmetric gears, they are superior to symmetric one in terms of load carrying capacity in one directional motion. Due to higher load carrying capacity in one directional motion, asymmetric gears have had great interest in turbine and aviation industry. Asymmetric spur gears can be produced by various manufacturing methods, such as hobbing, casting, precision forging. In this study, hot and warm precision forging of the asymmetric spur gears were investigated by using finite element method. In the simulations, workpiece temperature was selected as 1200 oC and 800 oC for hot and warm forging, respectively. Results of the simulations were compared in terms of required forging load, effective stresses, contact pressures and temperature distribution. 
 

Keywords: Asymmetric spur gear, precision forging, finite element method, warm forging, hot forging. Authors: Omer EYERCIOGLU, Mehmet ALADAG
Proceeding Book: 2. Uluslararası Türk Dünyası Mühendislik ve Fen Bilimleri Kongresi
ISBN:978-605-80038-4-2
Pages: 542-551
Full Text
5ANALYSIS OF DIMENSIONAL VARIATIONS OF PRECISION GEAR FORGING DIE GEOMETRY DUE TO SHRINK FIT

Özet

The usual way to shrink fit design for precision forging dies are made by thick wall cylinder approach; i.e., taking the pitch diameter of the gear as bore diameter of the die insert without considering gear tooth shape. However, the compressive pre-stress due to the shrink fitting causes dimensional variations on the gear profile of the die insert. The dimensional accuracy of the final product is dependent on the accuracy of the gear die. Therefore, the dimensional variations due to shrink fit must be pre-determined and the gear tooth profile on the die insert modified accordingly. In this study, the dimensional variations of the precision spur gear forging die because of shrink fitting are analyzed by finite element method and the results are compared with the experimental ones. The results show that the FE model is successful to simulate the cylindrical die and agree well with thick wall cylinder approach and the experimental measurements. However, both the experimental measurements and the finite element results of gear die predict much higher radial displacements than the results of cylindrical die. Therefore, the determination of shape change of the gear die profile is beyond the capability of the thick wall cylindrical approach.  

Keywords: Precision Gear Forging, Die Design, Shrink Fit, Finite Element
Authors: Omer EYERCIOGLU
Journal: European Journal of Engineering and Formal Sciences
ISSN:2601-6311
DOI:http://dx.doi.org/10.26417/ejef.v2i3.p87-95
Full Text
6EVALUATION OF TOOTH PROFILE CHANGES OF SYMMETRIC AND ASYMMETRIC SPUR GEAR FORGING DIES DUE TO SHRINK FIT

Özet

The compressive pre-stress due to the shrink fitting cause dimensional changes on the tooth profile of the precision gear forging dies. The accuracy of the gear die is directly affecting the accuracy of the final product. Therefore, the dimensional variations due to shrink fit must be pre-determined and the gear tooth profile on the die insert modified accordingly. In this study, the change of tooth profile of the symmetric and asymmetric precision spur gear forging dies because of shrink fitting are analyzed by finite element (FE) method and the results are compared with the experimental ones. Both the (CMM) measurements and the finite element results of gear dies predict much higher radial displacements than the results of the cylindrical approach (Lame Equations). The amount of radial displacements along the tooth profiles of both symmetric and asymmetric gear dies are not uniform and changing from root to tip of the tooth. The radial displacements of the asymmetric gear forging die are higher than the symmetric one.  

Keywords: Gear die, asymmetric gear, shrink fit, forging, involute profile
Authors: Omer EYERCIOGLU, Gulaga TAS, Mehmet ALADAG
Journal: Sigma Journal of Engineering and Natural Sciences
Issue:Year: 2020, Volume: 38, Issue: 1, (MAR 2020), pp:71 - 81
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7ASİMETRİK DÜZ DİŞLİ DÖVME İŞLEMİNİN ÜST SINIR ENERJİ METODU İLE ANALİZİ

Özet

Asimetrik dişliler özellikle tek yönlü güç ve hareket iletiminin olduğu uygulamalarda simetrik dişlilere göre daha üstün performansları nedeniyle tercih edilmektedirler. Asimetrik dişlilerin imalatında, hassas dövmecilik teknolojisinin kullanılması ile profilden kaynaklanan imalat sınırlandırmaların ortadan kaldırılması ve yüksek mukavemete sahip dişlilerin verimli bir şekilde üretilmesi mümkün olacaktır. Bu çalışmada, asimetrik düz dişlilerin hassas dövme işleminde, üst sınır enerji metodu (ÜSEM) kullanılarak dövme yükü ve malzeme akışının belirlenmesi için bir analiz sunulmuştur. Bu analizde, asimetrik dişin süren ve sürülen tarafları 12 şekil değiştirme bölgesine ayrılmıştır. Yapılan analizde, iş parçası malzemesinin isotropik ve homojen olduğu, dövme sırasında pekleşmediği, simetri ekseni boyunca malzeme geçişi olmadığı ve simetri ekseni üzerinde malzeme akış hızlarının eşit olduğunu varsayılmıştır. Bölgesel malzeme akış hızlarının hesaplanması ve enerji denklemlerinin çözümü, Python programlama dilinde geliştirilen bir yazılımla gerçekleştirilmiş ve interaktif bir kullanıcı arayüzü sunulmuştur. Prototip bir asimetrik dişli için dövme deneyleri yapılarak elde edilen sonuçlar üst sınır enerji analizi (ÜSEA ) sonuçlarıyla karşılaştırılmıştır. ÜSEA ile elde edilen dövme yükü değişimi ve malzeme akışı, deneysel sonuçlarla benzer olup maksimum dövme yükü göre %10’un altında bir sapma göstermiştir. Geliştirilen yazılım ile dövme yükü kısa bir süre içerisinde hesaplanabilmektedir. Hesaplanan maksimum dövme yükünün deneysel olarak belirlenenden daha yüksek olması, üst sınır enerji metodunun özelliğinden kaynaklanmakta olup, kalıp tasarımı ve pres kapasitesinin belirlenmesinde emniyetli bölgede kalmak için uygundur.  

Keywords: Asimetrik düz dişli, üst sınır enerji metodu, hassas dövmecilik, malzeme akışı, dövme yükü
Authors: Ömer Eyercioğlu, Gülağa Taş, Mehmet Aladağ
Journal:Gazi Üniversitesi Mühendislik Mimarlık Fakültesi Dergisi
DOI:https://doi.org/10.17341/gazimmfd.718534
ISSN:1300-1884