a roller bit

Using a foam roller is simple, but working some areas may take a bit of practice and some body contortion. You start by finding a relatively open area with some floor space.

使用泡沫轴很简单，但是要让它对身体一些部位的起到锻炼作用还需要一些练习和身体的柔韧性。

The paper introduced the successful application of high bench caving method of using deep hole roller rock bit into the practice of solving the complex goaf area, a stuff problem of this kind.

采用深孔牙轮钻机、利用高台阶崩落法成功地处理了复合采空区，解决了复合采空区处理难的问题，使技术人员在熟练浅采、深采空区处理的情况下，又探索出复合采空区的处理方法。

A modern design method, by which computer aided optimum design is used through the whole process of roller bit design, is introduced in this article.

介绍一种牙轮钻头的现代设计方法。设计过程全部使用计算机辅助设计和优化设计。