In order to attain the goal,the rotary speed of bit must be increased.By the action of high roatry speed,excentric shaft connection intensifies the fatigue failure of drill tool.

• 为了达到较好的防斜目的,必须增大钻进时钻头的转速,在高转速的作用下,偏轴接头加剧了钻具先期疲劳失效。