Kalıp çeliklerinin ortagonal tornalanması işlemlerinde kesme kuvvetlerinin modellenmesi ve kesici uç kaplama malzemelerinin etkilerinin incelenmesi
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Date
2000-10-16
Authors
Sığırtmaç, Tayfun
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Publisher
Uludağ Üniversitesi
Abstract
Tezin konusu, son zamanlarda talaş kaldırma alanında ortaya atılan kum tornalama yoluyla çok katlı ve kaplamasız takımların performanslarının incelenmesi ile ilgilidir. "İmalat Çeliklerinin Ortogonal Tornalanması İşlemlerinde Kesme Kuvvetlerinin Modellenmesi ve Kesici Uç Kaplama Malzemelerinin Etkilerinin İncelenmesi " adı altındaki tezde deneysel çalışmalarımız için üç farklı kesici takım seçilmiştir. Giriş bölümünde maliyet faktörünün talaşlı imalattaki yeri incelenmiş, kuru talaş kaldırma işleminin tanımı yapılmış ve bu eğilimin nedenlerinden bahsedilmiştir. Takımların ve tezgahların tarihsel gelişimleri hakkında bilgi verilmiştir. İkinci bölümde talaş kaldırma teorisi üzerinde kabaca durulmuş ve konu hakkında bir miktar açıklamalar yapılmıştır. Takım ömrünü belirleyici faktör olan takım aşınması incelenmiş ve bunların oluşumları literatürdeki bilgiler çerçevesinde açıklanmaya çalışılmıştır. Serbest yüzey aşınması VB ve krater aşınması KT ile gösterilmiştir. Aşınma - ömür bağıntıları Taylor denklemine göre incelenmiş ve konu ile ilgili bağıntılar verilmiştir. Üçüncü bölümde kesici takım malzemeleri tanıtılmış, kullanım alanları ve özellikleri hakkında bilgilere yer verilmiştir. Günümüzün en çok kullanılan kesici takım malzemeleri açıklanmış ve bu malzemelerin yapısal özellikleri üzerinde durulmuştur. Dördüncü bölümde ise tezimizde deneysel olarak inceleyeceğimiz kaplamalı ve kaplamasız kesici uçlarla ilgili bilgiler sunulmuştur. Her kaplama tabakasının üretim yöntemleri ve özellikleri hakkında açıklamalar yapılmış, bu yöntem ve tabakaların birbirleri ile olan ilişkilerine, karşılaştırmalarına değinilmiştir. Kaplama yöntemlerinden CVD ve PVD hakkında işlem proseslerini içeren bilgiler sunulmuş ve CVD işleminde oluşan Eta fazı anlatılmıştır. Ayrıca bu konuda literatürde yapılan deneysel çalışmalara yer verilmiştir. Deney faktörlerinin ve deney düzeneğinin açıklandığı Bölüm 5'te; deneylerin amacı, kullanılan tezgah, kesme kuvvetlerini ölçen dinamometre, kullanılan yazılım, kesici takım malzemeleri ve geometrileri, iş parçası malzemesi ile ilgili bilgiler anlatılmıştır. Kaplamalı takım olarak TiC+TiCN+TiN çok katlı ve TiC+Al203+TiN çok katlı kaplamalı takımlar kullanılmış, taban malzeme olarak da sinterlenmiş tungstenu karbür seçilmiştir. Kaplamasız takım olarak ise 3 faz yapılı (WC+Co+TiC/TaC/NbC) sinterlenmiş tungsten karbür takım kullanılmıştır. Deney sonuçlarının işlendiği Bölüm 6'da; kesme koşullan verilmiş, deney esnasında ölçümleri yapılan serbest yüzey aşınması gelişimi ve kesme kuvvetindeki değişimler tablolar halinde ve grafiksel olarak sunulmuştur. Toplam dört deney yapılmış ve herbir deneyde belli kesme uzunluklarında işlem durdurulmuş ve serbest yüzey aşınması mikroskop altında ölçülmüştür. Çap değişimi sebebiyle kesme hızında değişikler meydana gelmiş fakat her malzeme için ortalama kesme hızı değeri dikkate alınmıştır. Elde edilen deneysel verilerle herbir kesici kenarın aşmma-ömür grafikleri çizilmiştir. Son bölümde deney sonuçlan incelenmiş, takımlar arasındaki performans farklılıklan, kaplama tabakalan ve özellikleri ile açıklanmaya çalışılmıştır. Takımların performanslarını; kaldırdıklan talaş hacmi, kesme uzunluklan, kullanılan kesici kenar sayısı ve kesme işlemi için harcadıklan zaman gibi kriterler belirlemiştir. Takımlann performanslan ile şu andaki fiyatlan arasında değerlendirme yapılmış ve performans/fiyat belirlenmeye çalışılmıştır. Elde edilen aşınma grafiklerinin ilk aşınmaya kadar olan kısımları grafiğin yapısını bozduğu için o kısımlar dahil edilmemiş ve düzeltilmiş aşınma-takım ömrü grafikleri çizilmiştir. Regresyon analizi kullanarak bu verilerden polinomik denklemler elde edilmiş ve kolerasyon, belirlilik katsayılan (R2) ile doğruluk oranları hesaplanmıştır. 3., 5., ve 2., dereceden elde edilen bu denklemlerin pratikte kullanımı zor olduğu için doğrusal regresyon ile grafiklerin doğrusal haldeki denklemleri elde edilmiştir. Denklemlerin doğruluk ölçütü olan belirlilik katsayısı tüm doğrusal denklemlerde 0,9 değerinin üzerinde sonuçlar vermiştir. R2 nin 0,9'un üzerinde olması kabul edilebilir olduklarını göstermektedir.
The subject of the thesis is related with one of the recent subject in machining area as; examining the coated and uncoated tools performans while dry machining. We choosed three different kind of carbides for our experiments under the thesis with the name of 'Theoretical and Experimental Study About Dry Machining 1050 Quality Stell With Coated and Uncoated Carbides.' In the introduction part, the place of machining cost factor was investigated, the definition of dry machining and the reasons of tendency to this subject was explained. The tools and machines historical development was described. In the second chapter, the theorical machining processes were rudely explained. Tool wear which is determined the tool life was emphasized and its formation was tried to be stated. The flank wear and the crater wear were shown as VB and KT. Tol wear and tool life equations were given and explained. In the third chapter, the cutting tool metarials were described and some informations like their properties and usage areas were given. Recent most using tool metarials were stated and were dwelled upon. In the forth chapter, the coated and uncoated cutting tools which we used in our experiments were detaily described. Some explanations about coatings meterials, production proseses and the relations between these coating metarials with comparisons were given. The most popular two coating technology PVD and CVD were expressed and eta phase formation were also stated. Addition to these subjects in this chapter, experiments about machining with coated and uncoated tools were expounded. Expreriments mechanism and experiments factors were explained in fifth chapter. The informations were given about the tool machine, dynometer, software, cutting tool metarials and geometries, work piece metarial. Three different kind of cutting tool metarials were used. One is TiC+TiCN+TiN coated cementid carbide, other is TİC+AI2O3+TİN coated cementid carbide and the last one is uncoated cementid carbide. In the sixth chapter, cutting conditions while machining with coated and uncoated carbide, the development of flank wear and the variation of cutting forces were expressed by tables and charts. Totaly 4 main experiments were made and in everyIV experiment, the presses was stopped several times according to the cutting lenghts and the measurement of wears were made by microscope. Because of the changing of workpiece diameters, cutting speed was also varied. But the avarage value was considered as valid. With the datas which were taken from expriments, the tool life and tool wear charts were drawn. Finally, in the last chapter, the experiments results were investigated and the performance differences between tools were tried to explained by the coating layers differences. The tool performance was considered according to their machined layer volume, total cutting lenght, the number of used cutting edge and spent time for machining. The comparisons were made between tools prices and tools performances. The tool life-tool wear charts which were drawn from the experiments data werent used directly. The beginning of wears were not included the new charts. Because these parts are removed the charts characteristic properties. These new type of chart were called corrected chart. Then by using regression analys, the equations were created with minimum fault. R2 is show the truth level of our equations. As close as R2 to 1, this means it is very close to the real value. Instead of using high level equations, reducing their degrees to a linear form, they were become easy to use.
The subject of the thesis is related with one of the recent subject in machining area as; examining the coated and uncoated tools performans while dry machining. We choosed three different kind of carbides for our experiments under the thesis with the name of 'Theoretical and Experimental Study About Dry Machining 1050 Quality Stell With Coated and Uncoated Carbides.' In the introduction part, the place of machining cost factor was investigated, the definition of dry machining and the reasons of tendency to this subject was explained. The tools and machines historical development was described. In the second chapter, the theorical machining processes were rudely explained. Tool wear which is determined the tool life was emphasized and its formation was tried to be stated. The flank wear and the crater wear were shown as VB and KT. Tol wear and tool life equations were given and explained. In the third chapter, the cutting tool metarials were described and some informations like their properties and usage areas were given. Recent most using tool metarials were stated and were dwelled upon. In the forth chapter, the coated and uncoated cutting tools which we used in our experiments were detaily described. Some explanations about coatings meterials, production proseses and the relations between these coating metarials with comparisons were given. The most popular two coating technology PVD and CVD were expressed and eta phase formation were also stated. Addition to these subjects in this chapter, experiments about machining with coated and uncoated tools were expounded. Expreriments mechanism and experiments factors were explained in fifth chapter. The informations were given about the tool machine, dynometer, software, cutting tool metarials and geometries, work piece metarial. Three different kind of cutting tool metarials were used. One is TiC+TiCN+TiN coated cementid carbide, other is TİC+AI2O3+TİN coated cementid carbide and the last one is uncoated cementid carbide. In the sixth chapter, cutting conditions while machining with coated and uncoated carbide, the development of flank wear and the variation of cutting forces were expressed by tables and charts. Totaly 4 main experiments were made and in everyIV experiment, the presses was stopped several times according to the cutting lenghts and the measurement of wears were made by microscope. Because of the changing of workpiece diameters, cutting speed was also varied. But the avarage value was considered as valid. With the datas which were taken from expriments, the tool life and tool wear charts were drawn. Finally, in the last chapter, the experiments results were investigated and the performance differences between tools were tried to explained by the coating layers differences. The tool performance was considered according to their machined layer volume, total cutting lenght, the number of used cutting edge and spent time for machining. The comparisons were made between tools prices and tools performances. The tool life-tool wear charts which were drawn from the experiments data werent used directly. The beginning of wears were not included the new charts. Because these parts are removed the charts characteristic properties. These new type of chart were called corrected chart. Then by using regression analys, the equations were created with minimum fault. R2 is show the truth level of our equations. As close as R2 to 1, this means it is very close to the real value. Instead of using high level equations, reducing their degrees to a linear form, they were become easy to use.
Description
Keywords
Takım aşınması, Çelik-metal, Tool wear, Takım kaplama, Tool coating, Takım ömrü, Tool life, Steel-metal
Citation
Sığırtmaç, T. (2000). Kalıp çeliklerinin ortagonal tornalanması işlemlerinde kesme kuvvetlerinin modellenmesi ve kesici uç kaplama malzemelerinin etkilerinin incelenmesi. Yayınlanmamış yüksek lisans tezi. Uludağ Üniversitesi Fen Bilimleri Enstitüsü.