牙轮钻头牙齿破岩过程仿真

从运动学角度研究了牙轮钻头牙齿在井底的运动轨迹，并对牙齿的破岩过程进行了仿真分析。结果表明，牙齿的径向滑移主要与移轴距和吃入深度有关；牙齿的周向滑移主要与轮体转速比和吃入深度有关。移轴距、轮体转速比和吃入深度对破碎坑形状、大小和破碎环带宽度都有明显的影响。随着移轴距增大，破碎环带变宽，钻头对井底覆盖能力增强；随着轮体转速比增加，破碎坑明显变小。锥顶齿主要以刮削和挤压方式破碎井底中心区域；外排齿规径部位以切削方式破碎井壁过渡区。

Simulation of rock disintegrating process by roller cone bits

The motion loci of the teeth of a roller cone bit on bottom hole are studied as viewed from the kinematics and a simulation analysis of rock disintegrating process is carried out, The result shows that the radial slipping of the bit teeth is mainly related to the cone axis offset and the cutting depth and their circumferencial slipping is mainly related to the speed ratio between cone and body and the cutting depth.The cone alls offset, speed ratio between cone and body and the cutting depth have obvious influence on the shape and size of the breaking pits and the annular breaking width. The annular breaking width and the bottom hole coverage will increase with the increase of the cone axis offset.And the size of the breaking pits will be obviously reduced with the increase of the speed ratio between cone and body. The cone nose teeth break the rock at the center of the bottom mainly by scraping and extruding,and teeth on the gage surface break the rock on wall transition by cutting.