So the axial force is reduced, the fixing centre of the concave bit is stable and the concave bit has a long lifetime.

从而减小了轴向力，使钻头定心稳、寿命长，提高了钻削速度和工作效率。

youdao

So the axial force is reduced, the fixing centre of the concave bit is stable and the concave bit has a long lifetime.

从而减小了轴向力，使钻头定心稳、寿命长，提高了钻削速度和工作效率。

youdao