In order to obtain high transmission stiffness for the feed system of CNC machine tools, in addition to strengthening the stiffness of the ball screw nut itself, the correct installation of the ball screw and the structural stiffness of its support are also factors that can not be ignored. The inaccuracy of the bearing and its support at the end of the nut seat and screw and their excessive deformation after being stressed will affect the transmission stiffness of the feed system.

因此，螺母座的孔与螺母之间必须保持良好的配合，并应保证孔对端面的垂直度。螺母座应增加适当的肋板，并加大螺母座和机床结合部件的面积，以提高螺母座的局部刚度和接触刚度。

Therefore, it is necessary to keep a good fit between the hole of the nut seat and the nut, and ensure the perpendicularity of the hole to the end face. In order to improve the local stiffness and contact stiffness of the nut seat, the appropriate rib plate should be added to the nut seat, and the area of the nut seat and the joint parts of the machine tool should be increased.

滚珠丝杠的不正确及支承结构的刚度不足，会使滚珠丝杆的寿命大大下降。因此要注意轴承的选用和组合，尤其是轴向刚度要求较高。为了提高支承的轴向刚度，选择适当的滚动轴承及其支承方式是十分重要的。

If the ball screw is not correct and the stiffness of the supporting structure is insufficient, the service life of the ball screw will be greatly reduced. Therefore, attention should be paid to the selection and combination of bearings, especially the requirement of axial stiffness. In order to improve the axial stiffness of the bearing, it is very important to select the proper rolling bearing and its supporting mode.

(1)“双推一自由”式这种方式适用于短丝杠。

(1) "Double push one free" type is suitable for short lead screw.

(2)“双推一支承”式这种方式可避免丝杠因自重引起弯曲，以及高速回转时自由端的晃动。

(2) "Double push and one support" type can avoid the bending of lead screw due to self weight and the shaking of free end when rotating at high speed.

(3)“单推一单推”或“双推一单推”式它的优点是可对丝杠进行预拉伸安装。预拉伸的好处有：

(3) "Single push one single push" or "double push one single push" type has the advantage that the lead screw can be pre stretched and installed. The benefits of pre stretching are:

①减少丝杠因自重引起的弯曲。

① Reduce the bending of lead screw due to self weight.

②在推力轴承预紧力大于丝杠轴向载荷1／3的条件下，丝杠拉压刚度可提高四倍。

② When the preload of the thrust bearing is greater than 1 / 3 of the maximum axial load of the lead screw, the tension compression stiffness of the lead screw can be increased by four times.

③丝杠不会因温升而伸长(温升只减小预拉伸应力)，保持了丝杠精度。此外，这种支承方式使丝杠只承受拉力，不承受压力。因此不存在压杆稳定性问题。

③ The lead screw will not elongate due to temperature rise (the temperature rise only reduces the pre tensile stress), thus maintaining the accuracy of the lead screw. In addition, this supporting method makes the lead screw only bear tension, not pressure. Therefore, there is no stability problem.

(4)“双推一双推”式这种支承方式刚度。只要轴承无轴向间隙，丝杠的拉压刚度可提高四倍。可以进行预拉伸安装，克服热膨胀。当温升超过预计的温升时，不会像“单推一单推”式那样产生轴向间隙。这种支承方式的缺点是：实现预拉伸及其调整方法较第三种支承方式复杂。

(4) "Double push one double push" type has the highest stiffness. As long as the bearing has no axial clearance, the tension and compression stiffness of the lead screw can be increased by four times. It can be pre stretched to overcome thermal expansion. When the temperature rise exceeds the expected temperature rise, the axial clearance will not be generated as the "single push one single push" type. The biggest disadvantage of this supporting method is that it is more complex to realize pre stretching and its adjustment than the third one.