The optimum bit geometry for rotary drilling of boreholes in hard rocks

Autor: I. I. Kulishenko, V. I. Kovalev, S. Ya. Sologub, V. F. Vasil'chenko
Rok vydání: 1976
Předmět:
Zdroj: Soviet mining science. 12:612-614
ISSN: 1573-8736
0038-5581
DOI: 10.1007/bf02497456
Popis: As a result of the investigations we obtained graphs of the drilling speed and volumetric work of fracture vs the axial thrust. Analysis of these graphs reveals that the drilling speed of the RBT-3G increases about 1.85 times faster with the borehole length than that of the RB-42-2 and about 1.42 times faster than that of the RPKh-3; this is due to the lower relative wear of the bit under test. Industrial tests revealed that drilling bits of type RBT-3G with the new geometry, with ..cap alpha.. = -25/sup 0/, ..beta.. = 85/sup 0/, ..gamma.. = 30/sup 0/, give the best results both with regard to strength and durability and with regard to drilling speed in comparison with the commercially produced RB-42-2 and experimental RPKh-3 bits. Cylindrical hard-alloy plates with guides with a rake angle of -25/sup 0/ and backing-off angle of 85 to 90/sup 0/ give a uniform state of compressive stress. The use of hard-alloy plates of the recommended geometry permits us to create a rock-breaking tool of increased strength and durability with better operational characteristics than those of the bits presently in use.
Databáze: OpenAIRE
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