Several maintenance methods for ball screw nut pair

If the ball screw nut pair is not lubricated enough, the screw will rub, which will affect its accuracy and service life. If the ball screw nut pair has axial clearance, it will also affect the entire production process. So when there is a problem with the ball screw nut pair, how to maintain it? Here are a few methods to teach you.

 

1. Lubrication of round ball screw nut pair

 

Lubricants can improve the wear resistance and transmission efficiency of the ball screw nut pair. Lubricants can be divided into two categories: lubricating oil and grease. Lubricating oil is generally used in full-loss systems, and grease can be lithium-based grease. Grease is generally added to the thread raceway and the housing space where the nut is installed, and the lubricating oil is injected into the space of the nut through the oil hole on the housing. The grease on the ball screw should be replaced every six months, the old grease on the screw should be cleaned, and new grease should be applied.

 

2. Adjustment of axial clearance

 

In order to ensure the reverse transmission accuracy and axial stiffness, the axial clearance needs to be removed. The method of removing the gap of the double-nut ball screw pair is to use the relative axial displacement of the two nuts to make the balls in the two ball nuts close to the two opposite sides of the spiral raceway. In addition, the gap between the screw mounting part and the driving part must be removed. Commonly used methods for adjusting the gap of double-nut screws are: gasket gap adjustment, thread gap adjustment and tooth difference gap adjustment. The basic principle of the above three gap adjustment methods is to make the two nuts produce axial displacement to achieve the purpose of removing the gap and generating preload. However, the size of the preload force should be effectively controlled at this time. If the preload force is too small, the axial gap cannot be completely removed and the preload effect cannot be achieved; if the preload force is too large, the no-load torque will increase, thereby reducing the transmission efficiency and shortening the service life.

 

3. Regular inspection of support bearings

 

Regularly check whether the connection between the screw support and the bed is loose, whether the support bearing is damaged, and whether the parallelism between the screw and the guide rail is kept within the tolerance range. If there are any of the above problems, the loose parts should be strengthened in time, the support bearings should be replaced or the parallelism of the screw guide rails should be adjusted.

 

4. Protection of ball screw

 

Like other rolling friction transmission elements, ball screw nut pair needs to be equipped with protective devices to prevent hard dust or cutting dirt from entering. If the ball screw nut pair is exposed on the machine tool, a closed protective cover should be used, such as a spiral spring steel belt sleeve, a telescopic sleeve, and a folding sleeve. When installing, connect one end of the protective cover to the end face of the ball nut, and fix the other end to the support seat of the ball screw.

 

When using the ball screw nut pair, you can not only use it, but also learn to maintain the ball screw nut pair.