The Research On Cutting Mechanism And Experiment Of The Bionic Non-smooth PDC Cutter

In the geological、coal and oil exploration，and gas drilling，aiming at the soft tohard formation，the polycrystalline diamond compact (PDC) bit with the excellentcutting speed and longer service life has become one of the most popular rock tools.But with the extensive application of PDC bit，there are also some shortcomingsgradually exposed，for example：when PDC bit cutting rock with the constant wear ofPDC teeth，it can’t keep high speed；when drilling the mud and shale formation，itusually produces balling phenomenon，which influences and restricts the use effect ofPDC bit. The main reasons of the lack of the above are: the first one is that the linearexpansion coefficient of polycrystalline diamond and carbide is large that making thethermodynamics feature matching of the interface between polycrystalline diamondand carbide is not good，the larger residual thermal stress easily leads to separate thediamond and carbide interface layer and fail；the second one is that the PDC surface ismostly flat，to reduce the chip adhesion phenomena and quality inspection，thatgenerally take polishing treatment to improve the surface finish，ground into a mirror，the cost is high，but the anti-sticking effect is not obvious；The third one is that withthe constant wear of PDC blade，it work to form a flat or curved，and the contact areawith rock increased， the pressure of rock cutting droped， the speed of rockfragmentation is reduced，wear faster，especially for deep well、ultra deep welldrilling，frequent bit change will increase the drilling cycle and the drilling cost.In this paper，the bionic non-smooth theory is introduced and the bionicsprinciple and methods of topology is adopt，with the PDC cutter as basic of PDC bitcutting element，from the Angle of PDC cutter cutting，taking the mole cricket clawtoe and shells as bionic prototype to develop a new type of bionic non-smooth PDCtooth，which is efficient and sustained.Firstly，computer simulation analysis was carried out on the bionic PDC teeth:using ABAQUS software to analysis the finite element dynamic and compare the rockstress distribution between the bionic PDC tooth and conventional PDC tooth that the process of cutting the working，it is concluded that the interface between bionic PDCtooth and rock is multipoint stress concentration（data larger），and the one of theconventional PDC tooth is single point stress concentration （smaller data），whichshow that the bionic PDC tooth cutting first to break the limit under the same action，to realize the purpose of rapid breaking the rock；Secondly，the wear resistance ofbionic PDC tooth test: abrasion ratio test compared with conventional PDC tooth，theresults show that the abrasion ratio of the bionic PDC tooth is higher than the one ofthe conventional PDC cutter；Again，anti-sticking experiment: using homemade clay，taking adhesion test between the bionic PDC teeth and conventional PDC，the drillingtest found that the bionic PDC teeth can prevent stickiness more obvious thanconventional PDC cutter；Then，micro drilling test: prepared four different kind ofmicro drill bit that the caster angle is20°and15°，and the side corner is0°and5°，under the same kind of rock，testing the effect of drilling，it is concluded that twokinds of working Angle influence on the working performance of the cutter. Finally，carried on the field experiment: the test result is that when the service life of thebionic PDC drill bit is same with conventional PDC bit，the mechanical drilling rateincreased by2.6times.