Analysis On The Typical Geological PDC Bits' Stress Based On PRO/E Software

The strength of PDC bit have a decisive influence to drilling effect. A large amount of onspot drilling results indicates that above 90% bit is scrapped because of early shatter of aiguille body or failure of tooth, which causes a mass of waste. So it is necessary to study cutting load,strength and other aspects of the PDC bit which have important theoretical and practical significance.Firstly, according to analysis on invalidity bit, invalidity types of bit are summarized, they are bit body invalidity and cutting teeth invalidity. And also the main factors of invalidity are studied. Based on the study above, two types of typical geological PDC bit are selected as research objects. Secondly, the relation between bit cutting and rock is analized, based on the rock mechanics and cutting mechanics, then the stress formulas on shear plane and cutting plane of the bit cutting units model are derived. Finally, according to PRO/ENGINEER software, a typical geological PDC solid model is established, accroding to finite element analysis on the model, it is obtained that the deeper the cutting depth of cutting teeth, the lower the stress on cutting teeth, but wear rate accelerates; when other parameters are invariant, the greater the rock mechanics parameters, the greater the stess on cutting teeth; when the depth is invariant, as the cutting area becomes biger and arc-length becomes longer, the stress on the cutting teeth becomes lower. Then according to the analysis results, cutting teeth shape of bit is developed, and finite element analysis on bit developed is carried on. The results show that mechanical properties of PDC bit are improved. And reference for design of other PDC bit is provided through the study on geological PDC bit.