The ball screw nut pair is a high-precision transmission device. Using spiral rolling friction instead of spiral sliding friction has the characteristics of low wear, high transmission efficiency, smooth transmission, long life, high precision, and low temperature rise. Because the ball screw nut pair has small movement friction, it is easy to eliminate the outstanding advantages such as transmission gap, which brings huge benefits to the performance improvement of the mechatronics system. Defects: It cannot be self-locked, and a locking device is required for lifting or lifting transmission.
In order to prevent the ball from slipping, the self-locking performance of the ball screw nut pair is poor. It can be said that there is no pretension, and it is easy to fall off without pretension.
Not all ball screws are pre-tightened, mainly depending on the accuracy requirements. Generally, the pre-tightening accuracy is high and the load capacity is also large. The preload is graded and can be selected according to the requirements of use. For specific samples, you can view samples of different brands.
There are four ways to pre-tighten the ball screw:
1. Double nut washer pre-tightening.
The method is simple and reliable. Rugged and widely applicable. The pre-tightening force can be pre-adjusted by the professional manufacturer according to user requirements in the form of adding a washer between the double nuts. It is very convenient to use and unload.
2. Double nut type pre-tightening.
The pretensioner adopts a nut external thread, and the relative axial position of the two nuts is adjusted by a round nut to achieve pretension.
3. Double nut tooth difference pre-tightening.
The gears with a tooth difference of 1 are cut on the flanges of the two nuts respectively, and the gears are respectively meshed with the corresponding inner gear rings at both ends, and the inner gear rings are fixed on the nut seat with screws. Rotate a nut to change the mutual position of the two nuts, adjust the gap and apply pre-tightening force.
4. The single nut is self-preloaded with variable lead.
In the middle circle, the internal thread raceway of the nut produces a lead mutation, so that the balls on the left and right ends are axially misaligned after assembly to achieve pre-tightening.
The purpose of the ball screw nut pair to eliminate the axial gap: increase the pre-tightening force, reduce the idle stroke in the reverse direction, produce no reverse dead zone, and improve the transmission rigidity and transmission accuracy at the same time.