If the lubrication of the ball screw nut pair is insufficient, the friction of the screw will affect its accuracy and service life. If there is axial clearance in the ball screw nut pair, it will also affect the entire production process. So how to maintain the ball screw nut pair when there is a problem? Below, we will teach you several methods.
1. Lubrication of Round Ball Screw Nut Pair
Lubricants can improve the wear resistance and transmission efficiency of ball screw nut pairs. Lubricants can be divided into two categories: lubricating oil and lubricating grease. Lubricating oil is generally used for full loss systems, and lithium based grease can be used as lubricating grease. Lubricating grease is usually added to the threaded raceway and the housing space where the nut is installed, while lubricating oil is injected into the space of the nut through the oil hole on the housing. Replace the lubricating grease on the ball screw every six months, clean the old lubricating grease on the screw, and apply new lubricating grease.
2. Adjustment of axial clearance
In order to ensure the accuracy and axial stiffness of the reverse transmission, it is necessary to remove the axial clearance. The method of removing clearance in a double nut ball screw pair is to use the relative axial displacement of the two nuts, so that the balls in the two ball nuts are tightly attached to the two opposite sides of the spiral raceway. In addition, the gap between the screw installation part and the driving part should be removed. The commonly used methods for adjusting the clearance between double nut screws include gasket clearance adjustment, thread clearance adjustment, and tooth difference clearance adjustment. The basic principle of these three clearance adjustment methods is to cause axial displacement between the two nuts to remove the clearance and generate preload. But at this time, the size of the pre tightening force should be effectively controlled. If the pre tightening force is too small, it cannot completely remove the axial clearance and cannot achieve the pre tightening effect; If the preload force is too large, it will increase the no-load torque, thereby reducing transmission efficiency and shortening the service life.
3. Regular inspection of supporting bearings
Regularly check whether the connection between the screw support and the bed is loose, whether the supporting bearings are damaged, and whether the parallelism between the screw and the guide rail is maintained within the allowable tolerance range. If there are any of the above problems, it is necessary to promptly strengthen the loose parts, replace the supporting bearings or adjust the parallelism of the screw guide rail.
4. Protection of ball screw
Ball screw nut pairs, like other rolling friction transmission components, need to be equipped with protective devices to prevent hard dust or chip debris from entering. If the ball screw nut pair is exposed on the machine tool, a closed protective cover should be used, such as spiral spring steel strip sleeve, expansion sleeve, and folding sleeve. During installation, 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 ball screw nut pairs, one should not only know how to use them, but also learn how to maintain them.