Olgay Yaralı

Comparison of Drilling Performance of Chisel and Button Bits on the Electro Hydraulic Driller

Electro hydraulic drillers have been widely used in mining for drilling and roof-bolting. In the drilling process, the performance of the machine is predicted by selecting an appropriate bit type prior to drilling operations. In this paper, a series of field drilling studies were conducted in order to examine and compare the performance of chisel and button bits including wear on the bits. The effects of taper angle on chisel bits, which are at angles of 105°, 110° and 120°, were investigated in terms of rate of penetration, instantaneous drilling rate and specific energy. The results of drilling and abrasivity tests performed in the laboratory supported the outcome of the field studies. Based on laboratory studies and field observations, it was proven that the conglomerate encountered, though it is very abrasive, is easy to drill. The cutter life in the encountered series is also longer in sandstone formation compared to the conglomerate. Additionally, button bits resulted in lower specific energy and higher penetration rates relative to chisel bits, regardless of their taper angles. The results were also supported with statistical analyses.

The effects of specimen surface conditions and type of test apparatus on Cerchar Abrasivity Index

Cerchar abrasivity index test (CAI) is widely used for determining the abrasiveness of rocks. This test provides an index value that can be used as a gauge for the abrasiveness of rocks in order to estimate bit life and wear in various mining and tunneling applications. CAI studies in different laboratories show some variations in their values depending on the test apparatus (classic, west etc) used and tested specimen surface conditions. In this study, the effects of these factors on CAI were investigated. CAI tests were performed with two different test apparatus both on rough and on saw cut specimen surfaces of 13 different rock samples. This study showed that there have been some differences in the values of CAI between rough and saw cut surfaces. It is founded that rough surface CAI values were generally higher than the saw cut surface CAI values. The statistical analysis in this experiment indicates linear relation between CAI values on rough and saw cut surface and CAI values on rough surface is about 15% higher than CAI values on saw cut surface. It has been also found that the type of testing apparatus has insignificant effects on CAI measurements. In this study, CAI measured by Classical test device was higher than CAI measured West apparatus and this difference was about 1%.

Kayaç Özelliklerine Bağlı Olarak Kayaç Delinebilirliğinin Yapay Sinir Ağları (YSA) Metodu İle Tahmini

Bu calismanin amaci; kayac mekanik, indeks ve petrografik ozelliklerinden yararlanarak farkli yapay sinir aglari (YSA) modellemesi kullanilarak pratik bir delinebilirlik indeks modeli gelistirmektir. Bu amacla, laboratuvarimizda farkli kayaclar uzerinde yapilan DRI test verileri kullanilmistir. Ayrica diger kayac ozellikleri; mekanik (tek eksenli basinc ve Brazilian cekme dayanimi), indeks (Schmidt sertlik ve nokta yuku dayanimi) ve petrografik analiz (ortalama tane boyu, es deger kuvars icerigi (%), cimentolanma derecesi) sonuclari YSA modellemesi icin kullanilmistir. YSA modellemesinde degisken belirlemede, DRI ve diger (aciklayici) degiskenler arasindaki korelasyona bakilmis ve yuksek korelasyona sahip degiskenler YSA’na girdi parametresi olarak secilmistir. Secilen parametrelerden 14 veri agin egitimi icin, 7 veri ise test icin kullanilmis ve en anlamli sonucu veren model belirlenmistir. Testler sonucunda tahmin edilen DRI sonuclari ile deneylerden elde edilen gercek DRI sonuclarinin karsilastirmasi yapilmistir. Sonuc olarak YSA ile modellenen DRI sonuclarinin deneysel verilerden elde edilen sonuclara oldukca yakin oldugu gorulmustur.