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。
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。
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.
本装置采用圆锥表面磨法对钻头进行后面刃磨，可保证磨出的钻头具有合理的后角，对称精度高。
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