Abstract: Tooth-row arrangement is an important part of rock bit design,and has great effects on bit performance.Based on rock bit kinematics,the relationships between tooth-row arrangement and bottomhole breakage are studied,a new method of tooth-row arrangement design anslysis is established in this paper.On the basis of analyzing tooth trajectory,the scraping distance and velocity of every tooth-row is calculated.According to the outline formed by the radial trajectory of every tooth-row,the bottomhole radial breakage chart is given,which improves the traditional bottom coverage layout and can audio-visually reflect the effects of cone offset and tooth radial scraping distance on bottomhole breakage.A new delimitation method of bottomhole breakage annuluses and the calculation method of cutting volume per tooth are set up.It is shown that cutting volume per tooth should be as well-distributed as possilbe in bit design.

Key words: rock bit, kinematics, bit design, CAD, analytical method

摘要： 齿圈布置是牙轮钻头设计的一个重要内容,对牙轮钻头的工作性能和破岩效率有很大影响.本文在牙轮钻头运动学基础上研究了齿圈布置与井底破碎之间的关系,建立了系统地进行齿圈布置设计分析的新方法.根据牙齿在井底的运动分析,对钻头各圈牙齿在井底的滑移进行了定量的分析计算和各圈牙齿在井底径向平面内的运动轨迹所形成的包络线,作出了井底径向破碎图,它改进了传统的井底击碎图,可直观地反映移轴距和牙齿径向滑移对井底径向破碎的影响;建立了井底破碎环带划分和各齿圈单齿破岩量计算的新方法,指出齿圈布置设计,应尽可能均衡钻头各齿圈的单齿破岩量.这对牙轮钻头布齿设计具有重要指导意义.

关键词: 牙轮钻头, 运动学, 钻头设计, CAD分析方法