The core drilling method and the obtained achievement are introduced with respect to the bit and core barrel used in different formation.

根据不同地层所采用的钻头和取心器，介绍了不同地层的钻进取心方法和取得的成果。

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Objective:To introduce a new prefabricated post-and -core system, a helical drilling bit and a prefabricated post-and -core consisting of a root canal orifice bur which was designed by the author.

目的：介绍一种由螺旋型根管钻、自行设计的根管口台阶状车针、预成桩核组成的预成桩核系统。

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A new type of thin-wall diamond core drill bit is developed through the analysis of drilling feature on the r.

通过对在钢筋混疑土、花岗岩等建筑物上钻孔特点的分析，本文设计了一种新型的取芯式薄壁金钢石钻头。

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