The bit is usually a drag bit fitted with either PDC or naturaldiamond cutting structures, but the core bit is unusual in that it has a hole in its center.
钻头通常属于刮刀型，装备有PDC或者天然金刚石切削齿，但取芯钻头的特别之处在于钻头中心有一孔。
2
The invention also relates to a method for preparing the naturaldiamond impregnated bit.