Maintenance and maintenance of mechanical parts and auxiliary equipment of CNC machine tools (2)

2. Maintenance and maintenance of the feed transmission

The electromechanical components of the feed transmission mechanism mainly include: servo motor and detection component, speed reduction mechanism, ball screw nut pair, screw bearing, moving parts (workbench, headstock, column, etc.). Here we mainly explain the maintenance and maintenance of the ball screw nut pair.

(1) Adjustment of the axial clearance of the ball screw nut

In addition to the accuracy of the feed motion in a single direction, the ball screw nut pair also has strict requirements on the axial clearance to ensure the reverse transmission accuracy. Therefore, in operation and use, it should be noted that the axial clearance caused by the wear of the screw nut pair is eliminated by the adjustment method.

Double nut gasket type backlash

as the picture shows,

This type of structure is simple and reliable, has good rigidity, and is the most widely used. The form of gasket between the double nuts can be professionally produced.

The pre-tightening force is adjusted in advance according to the user's requirements, and it is very convenient to use the fashion unloading.

Double nut threaded backlash

as the picture shows,

The external thread on one nut is used to adjust the relative axial position of the two nuts by the round nut to realize the pre-tightening. After the adjustment, the other round nut is used for locking. This structure is convenient to adjust and can be adjusted at any time during use. However, the preload force cannot be accurately controlled.

Tooth difference backlash

as the picture shows,

Cylindrical external gears are respectively formed on the flanges of the two nuts, respectively meshing with the inner ring gears fastened at both ends of the sleeve, and the number of teeth is respectively Z1 and Z2, and one tooth is different. When adjusting, first remove the inner ring gear, let the two nuts rotate one tooth in the same direction with respect to the sleeve, and then insert the inner ring gear, then the two nuts will produce relative angular displacement, and the axial displacement is:

In the formula, Z1 and Z2 are the number of teeth of the gear, and Ph is the lead of the ball screw.

(2) Daily inspection of sealing and lubrication of ball screw nut pair

The daily inspection of the sealing and lubrication of the ball screw nut pair is a problem we should pay attention to during operation. For the sealing of the screw nut, it is necessary to check the sealing ring and the protective cover to prevent dust and impurities from entering the ball screw nut pair. For the lubrication of the screw nut, if grease is used, it should be lubricated regularly; if lubricating oil is used, it should be noted that oil is often injected through the oil hole.

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