When rotation speed is low, factors effecting soil delivering resistance are the soil volume carried by the vane and the spiral angle of drill.
采用两种不同螺旋角钻具对粘土进行输土实验，对比阻力结果证明了理论的正确性。
2
It can increase the hole inclination Angle range and drill elevation Angle holes, while setting the top drive power head and hole top plate toward the opposite direction.
动力头及孔口板调转方向，可直接钻凿仰孔，大大增加钻孔倾角范围。
3
The device is posterior cutter grinding to drill in cone surface grinding method that it can vouch for drill with reasonable back Angle, and symmetry precision is high.