当垂直刀架下降时，由于摩擦力阻碍其下降，使丝杆的上螺旋面螺母的下螺旋面相接触，丝杆螺母的间隙在下面。
When the vertical turret decline, due to friction hinder its decline, the screw on helical screw nut under the physiognomy contact screw nut in the space below.
用BP人工神经网络建立了重载丝杆螺母副的摩擦学特性与载荷之间关系的磨损自补偿数学模型。
The BP neural network used the wear-self-compensation mathematics model of the relationship of tribology characteristic with load of the heavy load screw-nut pairs was established.
阀杆采用防吹出保护结构，低摩擦系数的轴承等。
Protection structure with blowout proof stem, low coefficient of friction bearings and so on.
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