Theoretical analysis and research progress of heat conduction in the dry drilling and rock breaking process of bits

Abstract:

Drilling technology is pivotal in deep earth resource development and lunar exploration. The temperature fluctuations experienced by the bit under extreme working conditions such as dry drilling can lead to increased wear and potential failure of the bit. Therefore， analyzing the temperature rise mechanism is crucial for optimizing the drilling process and extending the life of the bit. Given the limitations of experimental methods in replicating extreme operational environments and the inherent simplifications in numerical simulations， constructing a theoretical model becomes essential to reveal the temperature rise behavior of the bit. This paper first analyzes the generation mechanisms of cutting force and cutting heat based on metal cutting theory， establishing a three-dimensional heat transfer differential model of the bit-rock-chip system. Subsequently， the temperature rise mechanisms of cemented carbide bits and PDC bits are compared from three perspectives： theoretical modeling， force analysis， and heat generation analysis. This comparison highlights the effectiveness of the model by simplifying the cutting structure and distinguishing between cutting and frictional heat. In contrast， the theoretical study of impregnated diamond bits has progressed more slowly due to the micro-cutting characteristics of diamond particles， dynamic changes in the height of the cutting edge， and uncertainties in the contact area. To develop a more adaptable thermodynamic model， future research should employ multi-physics coupling methods， incorporating rock properties， drill bit material properties， and dynamic operating parameters.