Research On The Inverted Bevel Gear Structure To Enhance The Strength Of The Fixed Teeth Of The High-temperature Drilling Roller Cone Bit

With the increasing difficulty of oil and natural gas exploitation,the hardness of mining strata continues to grow,and the emphasis on high-temperature geothermal resources is getting higher and higher.Geothermal environment with high temperature is harsh,the formation of rock is complex,and the temperature of bottom is often reach above 300 ?,making the phenomenon of tooth drop appears on roller cone bit usually,thus affecting the drilling efficient seriously.Under the condition of equal well depth,the cost of geothermal drilling is higher.Many experts and scholars,home and abroad,have conducted a lot of research and analysis on the drilling conditions of geothermal wells in high temperature and put forward the optimization scheme for the solidification intensity of the cone bit in order to improve the drilling efficiency and reduce the operating cost.The recent drilling engineering practices have shown that,under conditions of high-temperature drilling(especially high-temperature geothermal drilling),the original cone-shaped bit with excellent quality often suffers from severe tooth loss,shortens the life of the drill,and reduces the ability to protect the diameter.Affect drilling efficiency.This shows that the bottom hole temperature is a factor that has a significant influence on the solid tooth strength of the insert bit.The mechanism of action should be learned further and an effective method of solid tooth technology improvement should be studied.This paper proposes a new type of tooth with a reversed cone structure,which can prevent the occurrence of missing teeth theoretically and effectively.Conventional roller cone bits use cylindrical cemented carbide teeth and are fitted in the cylindrical tooth holes in a specific manner.The stress caused by the interference deformation of the insert teeth in this way will be The teeth are tightened to create a fixed tooth force.The structure of the new inverted bevel tooth structure is characterized by a large and small circular table,and the matching perforation structure feature is also a circular table shape in which the perforation hole diameter is smaller than the tooth root diameter.The two use hot or cold assembly for interference fit.When in the high temperature state,thanks to the inverted cone structure of the two,the maximum cross-sectional dimension of the tooth root is larger than the cross-sectional size of the tooth hole,so that in the case of thermal expansion,a good solid tooth effect can be produced,thereby effectively Reduce bit-loss phenomenon and improve drilling efficiency.The main research work of this paper includes:(1)Investigate and analyze the cause of tooth drop in a high temperature environment.Focus on the effects on the properties of roller cone bits of temperature,drilling methods,and tempering effects;(2)A series of theoretical calculations are made for the solid tooth strength of roller cone bits,and the specific analysis of the solid bite conditions,the pressure at the orifices,and the influence of temperature on the materials are given;(3)To propose a tooth structure with a reversed conical roller bit,which is fitted into the perforations by hot or cold mounting,it can have a greater fastening force and superior performance theoretically;(4)Taking the single-tooth model as an example,the Abaqus finite element analysis software was used to simulate the process of press-in,pull-out and application of lateral load under different conditions,and with the simulation results of the conventional cylindrical tooth under the same conditions CoMPared;(5)Concise description and analysis of the condition of the taper between the teeth and the perforations,the coMParison of the strength of the fixed teeth under several conditions of equal and unequal taper;(6)Two feasible methods are proposed to provide new ideas and solutions for the solid tooth of the roller bit under high temperature conditions.The results show that the reverse bevel tooth is less likely to peel off than the conventional cylindrical tooth under high temperature working conditions,and the protective effect is better after a certain load is applied,and its performance is better than the conventional cylindrical tooth.Through the research and analysis of this paper,it is of practical significance to improve the setting structure of roller bit and to improve the strength of solid tooth,and to enhance the adaptability of roller bit in high temperature environment.