冲击旋转加载下金刚石钻头－岩面动摩擦特性试验模拟研究

摘要

Inrotarydrillingprocess,theestimationofdynamicfrictioncharacteristicsbetweeninterfacesofdrillbit and concrete samples is an important issue for studying the rock crushing mechanism.Based on a self-developed drilling simulation system,the key parameters of friction were measured accurately and repeatedly by making use of stress waves. The axial pressure and friction force were obtained directly,and the relative sliding speed,sliding displacement as well as friction coefficient were further calculated.The results show that the relative sliding speed and sliding displacement between diamond drill and rock interfaces are highly related to the rotary loading rate.They will increase with the increase of rotational speed.The interfacial dynamic friction coefficient will increase with the rise of impact velocity.In each impact-rotation loading process,the experimental dynamic friction coefficient keeps almost constant and is not affected by the loading-unloading process of axial impact,the duration of stable dynamic friction is nearly equal to that of stress wave peak,and is gradually shortened with the increase of impact velocity,which reveals the characteristics of dynamic friction between drill bit and rock under impact-rotation loading.%为研究旋转式钻进过程中金刚石钻头与岩石接触界面动摩擦参量的变化规律，利用自主研发的钻进模拟系统，通过应力波精确、可重复测量钻头与混凝土试样间随时间变化的关键参量，直接获得轴压力、摩擦力，计算出相对滑动速度、滑动位移及摩擦系数。结果表明，金刚石钻头与试样间相对滑动速度、位移与旋转加载速率相关性较大，随其增加而增大；界面动摩擦系数随冲击速度增高而增大；在每次冲－旋加载过程中试验所得动摩擦系数基本恒定，不受轴向冲击加、卸载过程影响，稳定动摩擦力与应力波峰持续时长一致，且随冲击速度增加逐渐缩短，揭示出冲－旋加载作用下金刚石钻头与岩面之间动态摩擦特征。