Articles on: Learning & FAQ

Thread Backlash of Linear Motor and Countermeasures

First of all, a linear motor is essentially a combination of a stepper motor + screw nut. In a mechanism like a screw nut, when the screw threads mesh with the threads on the nut, they do not fit perfectly. At this time, there will be a slight gap between the meshed threads. This distance is what we call the backlash. Because the thread usually adopts a V-shaped structural design, it is precisely because of this design that there is a backlash. The backlash between the thread and the nut will affect the tightening strength, increase the possibility of loosening, and even cause thread damage.

The size of the clearances is related to the type, diameter and lead of the screw rod. At present, STEPPERONLINE's linear motor screws are divided into two types: trapezoidal screws and ball screws. Their respective clearances will be explained in detail below.

Trapezoidal screw: The backlash of this type of screw is usually 0.1-0.2mm. As long as the ratio of the diameter and lead of the screw is less than 1, then their backlashes are within this range. In addition, the larger the lead of the screw, the harder it is to control the backlash. Anti-backlash nuts are generally used to solve this problem.

Ball screw: This type of screw is famous for its high precision and high transmission efficiency, so the backlasheitself is very small and can almost be ignored. However, the backlash can also be reduced by increasing the preload. Preload is to adjust the size of the ball between the nut and the screw.

At present, the best way to eliminate the backlash is to replace the nut on the screw with an anti-backlash nut. The anti-backlash nut can eliminate the backlash between the thread and the nut. At this time, the backlash is theoretically 0mm, which can increase the tightening strength and extend the life of the thread.

As shown in the picture, this is a torsion spring anti-backlash nut, which is also the most commonly used anti-backlash nut at present. Basically all linear motors can customize this anti-backlash nut. It is equipped with a pressure core and a spring inside. These pressure cores The spring will deform when receiving external force, and the elastic force generated by the deformation will eliminate the play between the threads, so that the threaded nuts can be tightened together more firmly.

Updated on: 29/03/2024

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