Core drills. A core drill consists of the chamfer, body, neck, and shank, as shown in Fig.12.2. This type of drill may have either three or four flutes and equal number of margins, which ensure superior guidance, thus resulting in high machining accuracy.
空心钻 空心钻包括斜面、钻头体、钻颈和钻柄 如图12.2所示。这类钻头可以有三条或四条出屑槽及相同数量的保证良好导向的导向边 这样使得加工有高精度。
It can also be seen in Fig.12.2 that a core drill has flat end. The chamfer can have three or four cutting edges or lips, and the lip angle may vary between 90°and 120°.
在图12.2中同样能看到 空心钻具有平坦的端部。斜面可以有三或四条切削刃或钻唇 并且钻唇角可以在90°到120°之间变化。
Core drills are employed for enlarging previously made holes and not for originating holes. This type of drill is characterized by greater productivity, high machining accuracy, and superior quality of the drilled surfaces.
空心钻用于扩大已有的孔而不是打孔。这类钻头具有较大生产率、高加工精度和优良钻削表面质量的特性。