| Impregnated diamond bit(IDB)is the main tool for resource extraction and geological exploration.With the rapid development of national economy,the traditional IDBs with short life,low efficiency and energy consumption and other technical problems,have been difficult to meet the demand for resources,mining and geological exploration.Innovating the design concept,enhancing the service life and work efficiency of the IDBs are the key steps in promoting IDB upgrade.After millions of years,the biological in nature has evolved inherent wear-resistant,self-regenerated,self-healing,and self-lubricating function.It provides natural biological models for improving the drilling performance and working life of IDBs.Based on the bionic coupling theory,this study extracted the feature parameters of dung beetles and earthworm for designing the bionic coupling IDBs,which has dynamic non-smooth surface,in situ self-regeneration and self-lubricating function.And the wear resistance,synergism and self-regeneration mechanism of bionic coupling IDBs were explained by passive/active friction-wear test,near-working conditions drilling test and numerical simulation analysis.Provide more detailed theoretical and technical support for the development of bionic coupling IDBs,which has important technical value and scientific significance.Based on abrasive-ratio tests under passive grinding,it is found that the three kinds of bionic coupling elements can be coupled and synergistic,and the abrasion resistance and grinding ability of IDB samples are both better than the reference ones under passive grinding condition.The dynamic concave non-smooth surface is the key factor of improving the wear resistant and drilling performance.The self-lubricating function can produce good lubrication effects and reduce the interface friction.Too small gap at the contact interface and accumulation of the wear debris are two main reasons for the harmful wear and grinding mechanism.The bionic non-smooth surface can reduce or avoid this mechanism by increasing the space of frictional interface,trapping the wear debris and lubricating the contact.Based on the working principle of IDBs,the active grinding wear test were carried out to further research the effect of bionic units in different scales,quantity and arrangement on the wear behavior of bionic coupling IDBs.The relationships between the above factors and the wear behavior of the bionic coupling IDBs were revealed.The results of the abrasion test showed that the scale and quantity of unit can change the shear stress of the friction interface and the distribution of lubricating material,which further influence the wear behavior of bionic coupling IDB samples.In this paper,we design and fabricate bionic coupling IDBs in small diameter,and verified that the good wear resistance and drilling efficiency by micro-drill bench test under near-working conditions.The effects of the bionic unit arrangement,mechanical properties of the matrix material and self-regenerated function of the bionic unit on the wear resistance and drilling efficiency of the bionic coupling IDBs were researched.The study of the self-regenerated function of the bionic coupling micro-IDBs found that the bionic units on the bionic micro-bit have a self-adaptive ability.The bionic units can appropriately adjust the rate of self-regeneration and the final depth based on the physical properties of rock,provide suitable capacity of trapping abrasive debris and self-lubricating,and avoid the over-consumption of the bionic non-smooth materials.The non-smooth surface of the bionic coupling micro-IDBs can be achieved continuously to ensure that it continues to have a high wear resistance and drilling capacity.Thereby the service life of bionic coupling micro-IDB was extended,and the drilling efficiency increased within the working period.A three-dimensional finite element model of the interaction between IDB and rocks was established.The equivalent stress distribution of the reference IDB model,bionic coupling IDB model and rock model were simulated by ANSYS.ANSYS-FLUENT was used to simulate the external flow field and the temperature field of reference IDB model and bionic coupling IDB model respectively.Based on the finite element simulation,it is found that the bionic non-smooth surface can increase and evenly distribute the bottom surface stress,improve the self-sharpening ability of bionic IDB to ensure the synchronization of the whole sharpening of bionic coupling IDB;increase the equivalent stress which acting on the rock,make the rock easier to reach the yield stress,reduce the drilling energy consumption;the unloading effect can be made on the rock,so that the compressive stress area of the rock surface and the tensile stress area formed periodic alternating,resulted the fatigue cracks production;the torque reduction of the bionic IDB made the drill bit have a great effect,which increases the energy efficiency.The bionic non-smooth surface can provide more flow space of the coolant,increase the surface area for heat transferring,and enhance the flow rate of the coolant;can make the coolant form eddy current near the bionic unit,so that the heat transfer between coolant and IDB surface more fully and more efficiency,increase the working life of the bionic coupling IDB indirectly.Combined with the rock broken mechanism and wear characteristicsof IDBs,the gain effects and coupling mechanism of trapping debris,self-lubricating,reducing viscosity,stress uniformity,self-regeneration,self-adaptation were expounded systematically,based on the non-smooth wear resistance,drilling efficiency increasing and self-regeneration mechanism of bionic coupling IDBs.The wear resistance,drilling efficiency increasing,and bionic coupling mechanism of bionic coupling IDBs were revealed.The coupling efficacy evaluation index system of bionic coupling IDBs was established,and evaluated the bionic coupling efficacy of bionic coupling micro-IDBs,which provides a theoretical basis for the the optimization and perfection of bionic coupling IDBs. |
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